The Kynix Blog

This article is mainly to talk about the latest development of electric vehicle power management technology. Electric vehicle systems consist of electric motors, power converters, and energy storage devices such as lithium-ion batteries. This new architecture system must be optimized to maximize system efficiency, enabling the car to achieve maximum travel distance on a single charge. These developments in electronic technology have created conditions for reducing the emissions from transportation. Save our planet and keep the earth away from pollution! This is a consensus voice among scientists and people of insight around the world to reduce greenhouse gas emissions. Vehicles powered by fossil fuel combustion engines are the culprit. Although there are many alternative technologies to promote car travel, the only feasible solution at present is: electric cars.   Catalog   I Electric vehicles (EV) and hybrid electric vehicle (HEV) II Silicon carbide (SiC) power supply for electric vehicles III GaN power supply for electric vehicles IV Utilizing hybrid vehicle transmission system to reduce greenhouse gas emissions V Automotive inverter VI Dual-voltage battery system VII Delphi integration and wiring VIII Electric wheel drive system IX Conclusion FAQ I Electric vehicles (EV) and hybrid electric vehicle (HEV) An electric vehicle (EV) runs on a battery, as does a hybrid electrical vehicle (HEV), except that it also uses a fossil-fueled internal combustion engine as an aid. The technologies that power these cars need to be successful and have a bright future. Energy efficiency is the key. Therefore, intelligent power management mechanisms are needed to maximize the efficiency of converting battery energy into wheel mechanical driving force, thereby increasing single-charge charging. Travel distance, while not increasing carbon emissions, is ideally a significant reduction in carbon emissions. This video describe the operational characteristics of a hybrid vehicle drive train: Introduction to hybrid-electric vehicle energy monitor   II Silicon carbide (SiC) power supply for electric vehicles The weight, size, and cost of an electric vehicle, and the distance travelled by a single charge, are directly related to the efficiency of the power conversion system. SiC power components are ideal for working in the high temperature environments that are common in automobiles. Let us take a closer look at the role of silicon carbide power components in improving system efficiency. Lighter weight means longer mileage. A typical way to reduce the weight, cost, and size of a power conversion system is to increase the switching frequency of the switching regulator. We know that the size and weight of active components such as inductors, capacitors, and transformers can be reduced when operating at higher frequencies. Embrace the silicon carbide (SiC) solution. Although silicon (Si) power devices can also operate at high frequencies, the advantage of SiC is the ability to handle much higher voltages than Si. SiC is a wide band gap semiconductor device, and a wider band gap means a higher critical electric field (a critical electric field is a blocking voltage in an off state). The high voltage capability of wide bandgap (WBG) SiC devices allows them to have lower on-resistance, resulting in faster switching speeds and unipolar operation. Part of the principle is that their carrier frequencies need to be accelerated to much higher speeds (more High kinetic energy) to overcome wider band gaps. Although gallium arsenide (GaAs) and gallium nitride (GaN) also have high critical electric fields and are also improved devices for high-power solutions, SiC has other advantages, such as higher maximum operating temperatures. High Debye temperature, high thermal conductivity (in polycrystalline SiC), rapid switching and high resistivity saturation with low resistivity in the electric field, facilitated generation of lower silica (SiO2) The production cost, as well as the higher threshold energy brings more robust radiation resistance. SiC devices have many key applications in electric vehicles. The existing electric traction drive can convert 85% of the electrical energy into mechanical energy to drive the wheels. This efficiency is quite high, but SiC can also help improve efficiency. The power converter can benefit from improved efficiency because it transfers battery power to the engine and can be used in the battery charger circuit and any needed auxiliary power (Figure 1). Figure 1. SiC power devices have many uses in electric vehicles The SiC power supply that converts 750V to 27V for low-voltage electric vehicles is a good example of using SiC power devices to improve the efficiency of electric vehicles. This architecture increases efficiency from 88% to a staggering 96%, reduces size and weight by 25%, and does not require fans to cool excess heat compared to Si solutions. Table 1 shows some important applications of SiC power devices for electric vehicles. The reference information mentioned in the table can be found by referring to Reference 1 at the end of this article. Table 1. Some SiC applications in the electric vehicle electronics architecture III GaN power supply for electric vehicles Gallium nitride (GaN) also contributed to the improvement of the power supply of electric vehicles. IGBTs widely used in motor drive and DC/DC control have been silicon-based products. These designs typically have switching times on the order of 10kHz to 100kHz, while GaN devices can switch nanoseconds and can easily operate in a 200°C automotive environment. Like SiC, GaN devices can also reduce the size of inductors, capacitors, and transformers in power supply architectures due to their higher switching speeds. They can also reduce the overall size and weight due to the shrinking size of passive components. We will analyze their efficacy based on the chemical composition of electric vehicle batteries, such as lithium-based chemistry and NiMH with high energy density. As described in the previous SiC device section, the efficiency of the power conversion architecture also needs to be improved in order to enable longer distances for a single charge. The switching speed and minimum on-resistance of silicon devices have reached their maximum limit, and GaN seems to be a viable solution that exceeds these limits. Experiments show that if the switching frequency can be increased by 5 times, the inductor and capacitor can be reduced to one-fifth the size. Today's GaN technology can support very high speeds. GaN power devices perform quite well in four key areas: high temperature operation, higher breakdown voltage, low on-resistance, and nanoscale switching speeds for higher operating frequencies. GaN is similar to SiC in terms of these advantages. There are two differences between them: LEDs and RF transistors always use GaN; many silicon manufacturing processes are compatible with GaN processes, which reduces wafer costs and processes compared to the higher substrate costs of SiC. cost. Since the reliability problem was solved as early as 2003, today's technology has achieved the first batch of GaN high electron mobility transistor (HEMT) devices already in production. These are normal conduction devices, so the gate voltage of 0V will become conductive, and any voltage less than 0V will turn the device off. The SiC substrate was used early. Once the Si substrate is perfectly integrated with GaN, the production cost can be significantly reduced. The new cascaded architecture implemented in 2014 changed the ever-changing devices into normally-off devices. Since then, the drive technology has made great progress, the integration is getting higher and higher, and the power inverter has also made significant progress. GaN devices also perform well in battery chargers for electric vehicles, which consist of AC/DC converters plus DC/DC converters. This combination is a power factor controller (PFC) (Figure 2). Figure 2: A typical electric vehicle power architecture With GaN, coupled with higher switching speed GaN HEMTs, smaller passive devices can be realized. At higher frequency conditions, using a smaller inductor can make the ripple current of the power supply architecture lower, improve the power factor, and get a capacitor with a smaller size and lower cost. Lower ripple currents also have less stress on the capacitors, increasing their reliability and lifetime. Over the past few years, the reliability of GaN has been raised to a very high standard, which is the key to the use of GaN in automobiles. IV Utilizing hybrid vehicle transmission system to reduce greenhouse gas emissions At present about 72% of traffic emissions are generated by cars driving on the road. Improving the design of the hybrid powertrain drive system to increase its efficiency is the primary means of reducing emissions. One approach is to increase the efficiency of the DC-link voltage control architecture, which means that first it is necessary to increase the power converter efficiency of the series hybrid electric vehicle drive system. The DC-link is usually connected to three drive systems: a primary power supply consisting of a three-phase rectifier; a secondary power supply consisting of a dual active bridge (DAB) DC/DC converter; and a propulsion load consisting of a three-phase inverter ( Figure 3). They relate to tandem hybrid cars. Figure 3: Block diagram of the drive train of a hybrid vehicle In a design topology where the DC-link and battery voltages are not equal, an intermediate DC/DC converter solution is required. The paper "Voltage Control Methods for Improving Efficiency of Power Circuits in Series Hybrid Electric Vehicles" (Reference 3) describes many methods for studying different architectures and solutions for various DC-link voltage and DC/DC converter control. . The following will discuss the proportional control law that controls the dynamic DC-link voltage to achieve the phase shift between the waveforms of the gate switching of the DAB DC/DC converter bridge. This converter is located between the DC-link and the battery of a series hybrid vehicle drivetrain, as shown in Figure 4. In this case, the controller lowers the power consumption of the DC/DC converter and the entire drive system. Figure 4: Hybrid driveline interconnection diagram in the control schematic In this model, the diesel engine is the main power source of the hybrid vehicle, and the DC battery is the secondary power source. The supervisory control system (SCS) controls the ratio of power provided by the two power sources based on battery state of charge (SOC) and motor load. In fact, in this series hybrid vehicle, the DC-link voltage imposes restraint conditions on the ideal working area of PMSM and PMSG corresponding to the unit modulation index, so that the system can avoid signal distortion and reduce system efficiency. Overshoot state. Keeping the modulation index close to 1 can increase the total efficiency of the power circuit in the drive system, thereby maximizing the efficiency of the inverter and the rectifier, and the switching process is the main factor of its efficiency loss. Therefore, reducing the switching voltage can improve efficiency. This permanent zero pressure switch (PZVS) mechanism that minimizes power loss is best suited for cars with high mixing factors, especially in urban environments. The mixing factor (HF) is the ratio of the installed power from the power source to the total installed power. This mixing factor affects the fuel consumption in hybrid vehicles. V Automotive inverter The main power inverter controls the electric motor in the electric drive system and is an important component in the hybrid/electric vehicle. Power inverters, like engine management systems (EMS) in internal combustion engine cars, determine driving behavior. This inverter is suitable for any motor, such as synchronous, asynchronous or brushless motor, controlled by an integrated electronic PCB board. This PCB is specifically designed by automotive manufacturers to minimize switching losses and maximize thermal efficiency. The other function of the inverter is to capture the energy released by the regenerative brake and feedback to charge the battery. The distance traveled by hybrid/electric vehicles is directly related to the efficiency of the main inverter (Figure 5). Figure 5: Infineon main inverter block diagram in a hybrid/electric vehicle VI Dual-voltage battery system Managing batteries in hybrid and electric vehicles requires high-voltage technology. Dual-voltage systems incorporating 12V and 48V batteries require bi-directional DC/DC conversion, as shown in Figure 6, with the goal of protecting the circuit and supporting architectural functions. Figure 6: Bidirectional DC/DC converters from 48V to 12V In addition, automotive architecture designs typically have a single-phase 3.5kW or 7kW on-board charger module (OBCM) for charging an electric vehicle or plug-in hybrid electric vehicle (PHEV) from the grid. In contrast, electric vehicles and plug-in hybrid vehicles can be used as energy sources, and can also be used as energy storage devices in smart grids that integrate renewable energy. Smart grid work takes into account the smart charging and discharging of electric vehicles and plug-in hybrid vehicles. This is why OBCM must be a bi-directional DC/DC charger. The best architecture for this design is a boost series of resonant bi-directional topologies, as shown in Figure 7. It operates above the resonant frequency, has a zero-voltage switching function, and has maximum power transfer performance at the minimum switching frequency point. Compared to unidirectional power converters, this technology replaces diode rectifiers with MOSFET rectifiers. This solution also has higher efficiency and wider battery capacity. One of the major drawbacks of this architecture shown in Figure 7 is that the rectifier bridge has large losses when it is turned off. This problem must be addressed in future designs. Figure 7: Designers sometimes use a modulated DAB converter to control simple high-frequency isolation VII Delphi integration and wiring It is amazing that Delphi integrates all of the components discussed in this article and some of the other hybrid electric vehicle power electronics (Figure 8). Figure 8. Delphi achieves high integration in hybrid/electric vehicles It is also important to use suitable internal connectors in hybrid/electric vehicles (Figure 9). Figure 9. The key element of a hybrid/electric car is to minimize the quality     VIII Electric wheel drive system “Design and implementation of electric drive systems for in-vehicle electric vehicle applications” (Reference 8) proposes a hub drive system for hybrid and electric vehicles, and a hub-drive hybrid vehicle that provides computing performance. The SIMULINK model has been successfully developed. Two 14kW DC brushless DC (BLDC) motors are manufactured according to the literature and are installed in the rim of the hybrid vehicle wheels. In addition, two independently driven rear wheels are also mounted on Fiat's Linea. By detecting the angle of the steering wheel, electronic control technology replaces the mechanical differential device. The electric drive control system of the car and the electronic control unit (ECU) communicate via the CAN bus. A successful cascade is achieved between the electrically driven rear wheel and the ICE-driven front axle. Figure 10. A rear-wheel brushless DC motor image This design chose a brushless DC motor with a concentrated coil because it has a very low power-to-weight ratio and high efficiency, and it is easy to control. Figure 11. Exploded view of a direct-drive brushless DC motor in wheel rims and motor-generator units The brushless DC motor power drive consists of an integrated power module (IPM), an 8-bit microcontroller and an electronic control system. Driver software development for IGBT converter control and motor pulse width modulation (PWM) voltage control. The system has optocoupler isolation, current and temperature protection, and the system is also embedded with speed, current and voltage sensors. In summary, this article describes some recent developments in the power management of electric vehicles and hybrid vehicles. In the future, there will certainly be more development results that will be further improved to benefit our planet. IX Conclusion Electric propulsion technology requires the integration of a completely new architecture of the powertrain in the vehicle. This newly added component requires a multidisciplinary and in-depth study of the corresponding system components. Electric vehicle systems consist of electric motors, power converters, and energy storage devices such as lithium-ion batteries. This new architecture system must be optimized to maximize system efficiency, enabling the car to achieve maximum travel distance on a single charge. These developments in electronic technology have created conditions for reducing the emissions from transportation.   FAQ   1. What is energy management system in electric vehicles? Energy management strategies are the algorithms that decide the power split between engine and motor in order to improve the fuel economy and optimize the performance of HEVs. ... A lot of research work has been conducted for energy optimization and the same is extended for Plug-in Hybrid Electric Vehicles (PHEVs).   2. What is EV technology? EVs (also known as plug-in electric vehicles) derive all or part of their power from electricity supplied by the electric grid. They include AEVs and PHEVs. AEVs (all-electric vehicles) are powered by one or more electric motors. They receive electricity by plugging into the grid and store it in batteries.   3. What is the biggest challenge with electric vehicles? The major challenge is costs. Battery technology is expensive, and because batteries in electric cars need to be able to hold massive amounts of charge to make the cars practical for most drivers, they have to be built using expensive materials, most of which are tough to procure.   4. Why electric cars are bad for the environment? Nevertheless, at the end of the manufacturing process, electric cars are the ones generating more carbon emissions, according to the Union of Concerned Scientists. Why is this? Because electric cars store energy in large batteries (the larger they are, the bigger their range is) that have high environmental costs.   5. What are the main problems with electric cars? The biggest problem with EVs is range. While a plug-in hybrid can count on gasoline as a backup, EVs can't. An EV like the Tesla Model S can travel nearly 400 miles on a single charge, but not all EVs can make it quite that far. EVs like the Model S tend to be pretty expensive too.   6. What is meant by electric vehicle? An EV is a shortened acronym for an electric vehicle. EVs are vehicles that are either partially or fully powered on electric power. Electric vehicles have low running costs as they have less moving parts for maintaining and also very environmentally friendly as they use little or no fossil fuels (petrol or diesel).   7. How do electric vehicles work? Electric cars function by plugging into a charge point and taking electricity from the grid. They store the electricity in rechargeable batteries that power an electric motor, which turns the wheels. Electric cars accelerate faster than vehicles with traditional fuel engines – so they feel lighter to drive.   8. What are the types of electric vehicles? There are two basic types of EVs: all-electric vehicles (AEVs) and plug-in hybrid electric vehicles (PHEVs). AEVs include Battery Electric Vehicles (BEVs) and Fuel Cell Electric Vehicles (FCEVs).   9. Do electric cars run on AC or DC? Electric cars can use AC or DC motors: If the motor is a DC motor, then it may run on anything from 96 to 192 volts. Many of the DC motors used in electric cars come from the electric forklift industry.   10. Are there any benefits of owning an electric car? They can reduce emissions and even save you money. Fueling with electricity offers some advantages not available in conventional internal combustion engine vehicles. Because electric motors react quickly, EVs are very responsive and have very good torque.  

Today in this article we will discuss about how PCB is developed and its industrial trend. Printed circuit board, also called PCB, is an important electronic component and the support of electronic components, which also have a circuit in which a metal conductor can be connected to an electronic component. Nowadays electronic equipment requires high performance, high speed and thin miniaturization. As a multidisciplinary industry, PCB is the key technology of high-end electronic equipment. It plays an important role in electronic interconnection technology. Introduction to how PCB worksCatalogI PCB overviewII. Main types of PCB2.1 Single-sided boards2.2 Double-sided boards2.3 Multi-layer boardsIII Industrial chain of PCB3.1 Glass fiber cloth3.2 Copper foil3.3 Copper clad laminateIV Development of PCB industry in ChinaFAQI PCB overviewTraditional circuit boards are referred to as printed circuit boards because the circuit and its surface are created using the printing etching inhibitor method. At the moment, most circuit boards are made by using an etching inhibitor (film pressing or coating), and then etching is used to make the circuit board after exposure and development.Due to the continuous miniaturization and refinement of electronic products, most of the current circuit boards are coated with etching inhibitors (film pressing or coating). After exposure and development, the board will be etched to form the final circuit board. PCBs have progressed from single-sided to double-sided, multilayer, and flexible boards, and this trend is expected to continue. Because of its ongoing advancements in the areas of high precision, high density, and high reliability. PCB maintains a strong vitality in future electronic equipment development projects due to its continuous development of high precision, high density, and high reliability, reducing volume, cost, and improving performance.Printed circuit boardThe discussion of the development trend of the future PCB manufacturing technology at home and abroad is almost consistent, that is, developing toward the direction of high density, high precision, fine aperture, fine wire, fine spacing, high reliability, multilayer, high speed transmission, light weight and thin shape. At the same time, it is aimed to increase productivity, reduce costs, reduce pollution, adapt to multi-species and small run production during manufacturing. The technical development level of printed circuit is represented by the line width, aperture and the ratio of thickness to aperture of printed circuit.The creator of the printed circuit board was an Austrian called Paul Eisler. In 1936, he first used a printed circuit board in a radio. In 1943, Americans mainly applied this technology to military radios. Then in 1948, this invention was officially approved for commercial use in the United States.  Since the middle of 1950s, printed circuit boards have been widely used.Before the emergence of PCB, the interconnection of electronic components was accomplished by direct connection of electrical wires. Nowadays, wires exist only for laboratory applications. Printed circuit boards (PCB) have definitely occupied the position of absolute control in the electronic industry. II Main types of PCBAccording to the number of circuit layers, it can be divided into single-sided board, double-sided and multilayer board. The common multilayer board is usually 4 or 6 layers, and the complex multilayer board can have dozens of layers. Printed circuit boards are mainly divided into three types:2.1 Single-sided boardsOn the most basic PCB, the parts are concentrated on one side and the wire will be on the other (when there is patch element, it is on the same side as the wire, and the plug-in device is on the other side). Because the wire only appears on one side, this type of PCB is called single-sided board. The single-sided board has many strict restrictions on the design circuit (since there is only one side, the wiring cannot intersect and have to go around a separate path), so only the early circuits use this type of board.2.2 Doublesided boardsThere are wiring on both sides of this kind of circuit board.However, to use these two sides of the wire, you must have an appropriate circuit connection between the two sides. The "bridge" between these circuits is called “via”. The via hole is a small hole filled or coated with metal on the PCB, which can be connected to both sides of the wire. It can be connected to two sides of the wire. Because the area of the double-sided board is twice as large as that of the single panel,  it solves the difficulty of wiring interleaving in the single panel (it can get to the other side through the hole), so it is more suitable for the circuit which is more complicated than the single sided.2.3 Multi-layer boardsIn order to increase the area in which wiring can be made, the multilayer board is made up of more single or double-sided wiring boards. A printed circuit board with one side as the inner layer, two single sides as the outer layer or two sides as the inner layer, and two single sides as the outer layer, which is interlinked with conductive patterns according to the design requirements, is composed of four layers and six layers of printed circuit boards, also known as multilayer printed circuit boards (PCB). The number of layers on the board does not mean that there are several independent wiring layers. In special cases, an empty layer is added to control the thickness of the board, and the number of layers is usually even, and contains the outermost two layers. Most motherboards are 4 to 8 layers, but technically we can do nearly 100 layers of PCB. Large scale supercomputers mostly use quite many layers of motherboards. However, because such computers have been replaced by clusters of many common computers, super multilayer boards have been gradually unused. Because the layers in the PCB are tightly combined, it is generally not easy to see the actual number, but if you look closely at the motherboard, you can see it. Also there are two kind of boards called rigid and flexible printed boards. > Rigid and Flexible Printed BoardsDivided into rigid circuit boards, flexible circuit boards and rigid-flexible printed circuit boards. The PCB shown in the first picture below is generally referred to as the rigid PCB, and the yellow connection line in the second picture is called flexible PCB. The intuitive difference between a rigid PCB and a flexible PCB is that the flexible PCB is flexible. The common thickness of rigid PCB is 0.2mm / 0.4mm / 0.6mm / 0.8mm / 1.0mm / 1.2mm / 1.6mm / 2.0mm etc. The common thickness of flexible PCB is 0.2mm. The thickening layer is added to the back where the parts are to be welded , and the thickness of the thickened layer varies from 0.2 mm to 0.4 mm. TThe purpose of understanding these is to provide them with a spatial reference for the design of a structural engineer. The common materials for rigid PCB include: phenolic paper laminates, epoxy paper laminates, Polyester glass felt laminates, epoxy glass cloth laminates; flexible PCB materials include: polyester film, polyimide film, ethylene propylene fluoride film.Rigid boardFlexible board III Industrial chain of PCBAccording to the upstream and downstream classification of the industrial chain, PCB industry can be divided into raw materials - CCL (copper-clad laminate) - PCB (printed circuit board) - electronic product application. The relationship is simply expressed as: 3.1 Glass fiber clothGlass fiber cloth is one of the raw materials of copper clad plate, which is made of glass fiber yarn and account for about 40% of the cost of copper clad laminate (thick plate) and 25% (thin plate). Glass fiber yarn is calcined into liquid state from raw materials such as silica sand in the kiln, then pulled into very fine glass fiber through extremely small alloy nozzles, and then hundreds of glass fibers are twisted into glass fiber yarn. The manufacture of glass fabric is similar to that of weaving enterprises. It can control production capacity and quality by controlling rotation speed, and the specifications are relatively single and stable. Since World War II, there has been almost no significant change in specifications.Unlike CCL, prices of glass fabrics are the most affected by supply and demand, fluctuating between $0.50-1.00 a meter in recent years. Taiwan and mainland China account for about 70% of the world's production capacity.3.2 Copper foilCopper foil is the raw material that accounts for the largest proportion of the cost of copper clad laminate, about 30% of the cost of copper clad plate (thick plate) and 50% (thin plate). Therefore the price increase of copper foil is the main driving force of the price increase of copper clad laminate. The price of copper foil is closely reflected in the change of copper price. However, the bargaining power is relatively weak. With the rising copper prices, copper foil manufacturers are in a difficult situation, and many enterprises have been forced to close down or be annexed. Even if copper clad laminate manufacturers accept copper foil price increases, copper foil manufacturers are still in a general loss. Another wave of price increases is likely to occur in the first quarter of 2006, possibly driving up CCL prices due to the price gap. 3.3 Copper clad laminateCopper clad laminate (CCL) is a direct raw material of PCB, which uses epoxy resin as fusion agent to press glass fiber cloth and copper foil to make printed circuit board (PCB) after etching, electroplating and multilayer laminate pressing. The copper clad laminate industry is not in high demand for capital, about 3 million to 40 million yuan, and can be stopped or converted at any time. In the upstream and downstream industrial chain structure, CCL has the strongest bargaining power. It has a strong voice in the procurement of glass fiber cloth, copper foil and other raw materials , and as long as the demand of downstream is good, the manufacturer of CCL can transfer the pressure of rising costs to the downstream PCB manufacturers. IV Development of PCB industry in ChinaThe development of PCB in China began in 1956. In 1963-1978, it is gradually expanded to be the PCB industry. More than 20 years after the reform and opening up, due to the introduction of foreign advanced technology and equipment, single-sided board, double-sided board and multi-layer board had a rapid development. The domestic PCB industry has gradually developed from small to large scale.Due to the concentration of downstream industries and relatively low labor and land costs, China has become the region with the strongest development momentum. In 2002, China became the third largest output country of PCB. In 2003, the output value and import and export volume of PCB exceeded $6 billion, which overtaking the United States for the first time and becoming the second largest output country in the world. The proportion of output value also increased from 8.54% in 2000 to 15.30%, nearly doubling. In 2006, China has replaced Japan as the world's largest PCB production base and the most active technology development country. China's PCB industry has maintained a high growth rate of about 20%, which is far higher than that of the global PCB industry. In terms of production composition, the main products of China's PCB industry have shifted from single-sided and dual-sided to multilayer, and are being upgraded from 4-6 layers to more than 6-8 layers. With the rapid growth of multilayer printed board, HDI board and flexible boards, China's PCB industrial structure is gradually being optimized and improved. However, although China's PCB industry has made considerable progress, there is still a big gap compared with advanced countries, and there is still much room for improvement in the future. First of all, China's entry into the PCB industry is relatively late and there are no specialized PCB research and development institution. There is a big gap between the research and development capabilities of some new technologies and foreign manufacturers. Secondly, in terms of product structure, the production of medium and low laminates is still dominated. Although FPC and HDI boards are growing rapidly, the proportion is still low because of its small base. Most of our PCB production equipment depends on imports, and some core raw materials can only rely on imports. The industrial chain is incomplete, which also hindered the domestic PCB series enterprise's development step.  FAQ 1. What is PCB?A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. 2. What is PCB and types of PCB?A printed circuit board (PCB) is a thin board made from fiberglass, composite epoxy, or other laminate materials. PCBs are found in various electrical and electronic components such as beepers, radios, radars, computer systems, etc. Different types of PCBs are used based on the applications. 3. What can a PCB be used for?Printed circuit boards (PCBs) are used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate, employed in the manufacturing of business machines and computers, as well as communication ... 4. Why are PCB green?It is due to the solder mask, which protects the copper circuits printed on the fibre glass core to prevent short circuits, soldering errors, etc. ... The colour of the solder mask gives the board its appearance. 5. What is PCB and its advantages?Compact Size and Saving of Wire. A characteristic PCB includes a large number of electronic components. On a Printed circuit board, the interconnection between the components is made through copper tracks instead of using a number of current carrying wires. It makes the interconnections less bulky. 6. How long does it take for PCBs to break down?3.5 to 83 days. The time it takes for half of the amount of PCBs (initially) present to be broken down ranges from 3.5 to 83 days for molecules with 1 to 5 chlorine atoms. In water, PCBs are essentially broken down by the effect of sunlight (photolysis). 7. What is the disadvantage of PCB?Disadvantages: Easy to Cause Handling Damage. Process Uses a Carcinogen (Thiourea) Exposed Tin on Final Assembly can Corrode. 8. Which PCB design software is the best for beginners?Top Best PCB Design Software of 2021a. PROTEL (Altium Designer) b.PADS (PowerPCB) c. ORCAD. d. Allegro. e. Eagle（Easily Applicable Graphical Layout Editor）f. Kicad.g. EasyEda.h. Fritzing. 9. What are the advantage of flexible PCB?The flexible circuit board are designed for saving room and improving the flexibility to meet a smaller and higher density mounting design, it also helps to reduce the assembly process and enhance reliability. 10. Why do we use PCB instead of breadboard circuit?The advantages of a printed circuit board: the board is permanent to have an electronic device worked. PCB has a better current carrying capacity comparing to a breadboard, you can make your traces wider to take more current so that work well. ... You can mount heat-sinks to the board so that have them rigid. 11. What PCB means?Printed-Circuit-BoardA printed circuit board, or PC board, or PCB, is a non-conductive material with conductive lines printed or etched. Electronic components are mounted on the board and the traces connect the components together to form a working circuit or assembly. 12. Why are PCBs dangerous for humans?PCBs are a probable human carcinogen.Studies of PCBs in humans have found increased rates of melanomas, liver cancer, gall bladder cancer, biliary tract cancer, gastrointestinal tract cancer, and brain cancer, and may be linked to breast cancer. 13. What are PCBs in electronics?A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. 14. Why are PCB green?It is due to the solder mask, which protects the copper circuits printed on the fibre glass core to prevent short circuits, soldering errors, etc. ... The colour of the solder mask gives the board its appearance. 15. What is PCB and its role?A process control block (PCB) is a data structure used by computer operating systems to store all the information about a process. It is also known as a process descriptor. When a process is created (initialized or installed), the operating system creates a corresponding process control block. 16. Which software is best for PCB design?- NI Multisim.- KiCad EDA.- Autodesk EAGLE.- DipTrace.- Ultiboard.- CAM350.- ExpressPCB Plus.- SolidWorks PCB. 

Warm hints: this article reading time is about 15 minutes. This article is mainly about learning several kinds of industrial weapons - sensors. Automation technology is a comprehensive technology. It has a very close relationship with cybernetics, information theory, systems engineering, computer technology, electronics, hydraulic pressure technology, and automatic control, among which automation is based on control theory and computer technology.   CatalogI、Automation TechnologyII、Physical SensorIII、Fiber Optic SensorIV、Bionic SensorV、Infrared SensorVI、Electromagnetic SensorVII、Magneto-optical Effect SensorVIII、How to Choose Industrial SensorsFAQ I. Automation Technology Automation technology is a comprehensive technology. It has a very close relationship with cybernetics, information theory, system engineering, computer technology, electronics, hydraulic pressure technology, automatic control, etc., of which automation and control theory and computer technology The most influential technology. There are a lot of special equipment in automation technology, just like the different weapons, the author made a count of the automated weapons below.II. Physical SensorPhysical sensorSensor (Sensor) is a common but very important device. A sensor is a device, module, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. For the sensor, the input can be divided into static and dynamic according to the input state. We can get the static characteristics of the sensor based on the relationship between the output and the input based on the steady-state of each value.  The main indicators of the static characteristics of the sensor are linearity, hysteresis, repeatability, sensitivity, and accuracy. The dynamic characteristics of a sensor refer to the response characteristics of the input over time. Dynamic characteristics are usually described using automatically controlled models such as transfer functions. In general, the signal received by the sensor has a weak low-frequency signal, and the amplitude of the external interference sometimes exceeds the measured signal. Therefore, eliminating the noise in series becomes a key sensor technology. The physical sensor is a sensor that detects physical quantities by the use of certain physical effects. The sensor can convert measured physical volume into a form of energy to facilitate the processing of the signal device. The output signal and the input signal have a definite relationship. The main physical sensors include photoelectric sensors, piezoelectric sensors, piezoresistive sensors, electromagnetic sensors, pyroelectric sensors, and optical fiber sensors.  As an example, let us look at the more commonly used photoelectric sensors. This kind of sensor converts the optical signal into an electrical signal. It directly detects the radiation information from the object and can also convert other physical quantities into an optical signal. The main principle is the photoelectric effect: When the light is irradiated to the material, the electrical effect on the material changes, and the electrical effects here include electron emission, conductivity, and potential current. Obviously, a device that can easily produce such an effect becomes a major component of a photoelectric sensor, such as a photoresistor.  In this way, we know that the main working process of a photoelectric sensor is to receive the corresponding light, convert the light energy into electricity through a device such as a photosensitive resistance, and then obtain the required output by amplification and denoising electric signal. The output electrical signal here has a certain relationship with the original optical signal, which is usually close to a linear relationship so that the calculation of the original optical signal is not very complicated. The principles of other physical sensors can be compared to optical sensors. The range of applications of physical sensors is very extensive. We look at the application of physical sensors from the perspective of biomedical sciences. It is not difficult to infer that physical sensors have important applications in other aspects. For example, blood pressure measurement is the most common type of medical measurement. Our usual blood pressure measurement is an indirect measure of the blood pressure in the vessel by measuring the relationship between blood flow and pressure detected by the body surface. The sensors needed to measure blood pressure usually include an elastic diaphragm that transforms the pressure signal into a deformation of the diaphragm and then converts it into a corresponding electrical signal based on the strain or displacement of the diaphragm. At the peak of the electrical signal, we can detect systolic pressure. After passing through the inverter and the peak detector, we can get the diastolic pressure. The average pressure can be obtained through the integrator. Let us look again at breath measurement technology. Respiratory measurement is an important basis for the clinical diagnosis of lung function and is essential in surgery and patient monitoring. For example, when using a thermistor sensor for measuring respiratory rate, mount the sensor's resistance on the outside of the front end of a clip, clip the clip over the nose, and pass the heat as the flow of breathing gas flows from the thermistor surface Sensitive resistance to measure the frequency of breathing and the status of hot gas. Another example of the most common body surface temperature measurement process. Although it seems easy, it has a complex measurement mechanism. The body surface temperature is determined by various factors such as the local blood flow, the heat conduction of the underlying tissue, and the heat dissipation of the epidermis. Therefore, the measurement of the skin temperature must take into account various influences.  Thermocouple sensors are more commonly used in the measurement of temperature, usually rod-shaped thermocouple sensors and thin-film thermocouple sensors. Because the size of the thermocouple is very small and the accuracy is relatively high, it is possible to measure the temperature at a certain point accurately. With the help of later analysis statistics, a more comprehensive analysis result can be obtained. This is incomparable with the traditional mercury thermometer, but also shows the broad prospects for the application of new technologies to scientific development. From the above introduction, it can be seen that physical sensors have a variety of applications just in biomedical applications. The development direction of the sensor is a multifunctional, imaged, intelligent sensor. Sensor measurement as an important means of data acquisition is indispensable for industrial production and even family life, and physical sensors are the most common family of sensors. The flexible use of physical sensors will inevitably create more products and better benefits. III. Fiber Optic SensorFiber optic sensorIn recent years, sensors have evolved in the direction of sensitivity, precision, adaptability, compactness, and intelligence. In the process, fiber optic sensors are a new addition to the sensor family. Optical fiber has many excellent properties, such as anti-electromagnetic interference and atomic radiation performance, fine diameter, soft, lightweight mechanical properties, insulation, non-inductive electrical properties, water resistance, high-temperature resistance, corrosion resistance, chemical properties, etc. It can reach people's eyes and ears in unattainable places (such as high-temperature areas), or in areas harmful to humans (such as nuclear radiation area), but also can transcend human physiological boundaries and receive sensory organs Unforeseen outside information. Optical fiber sensors are new technologies that have emerged in recent years. It can be used to measure a variety of physical quantities, such as sound fields, electric fields, pressures, temperatures, angular velocities, and accelerations, as well as measurement tasks that are difficult to accomplish with existing measurement techniques. In tight spaces, fiber optic sensors show unique capabilities in environments with strong electromagnetic interference and high voltage. At present, there are more than 70 optical fiber sensors, which are roughly divided into optical fiber sensors and optical fiber sensors. The so-called optical fiber sensor itself is the optical fiber directly to receive the outside world was measured. The external measured physical quantity can cause the length, refractive index, and diameter of the measuring arm to change so that the light transmitted within the fiber changes in amplitude, phase, frequency, polarization, and the like. The light transmitted by the measuring arm interferes (compares) with the reference light of the reference arm to change the phase (or amplitude) of the output light, and the change in the measured light can be detected based on this change. The phase of the transmission in the optical fiber is highly sensitive to external influences, and the interferometric technique can detect the physical quantity corresponding to the slight phase change of 10 negative quadratic arcs. For the optical fiber’s winding and low loss characteristics, we can disc a long fiber optic into a small diameter optical fiber ring in order to increase the length, to obtain higher sensitivity. An optical fiber acoustic sensor is a kind of sensor using the optical fiber itself. When the fiber is a little tiny external force, it will produce micro-bending, and its light transmission capacity has undergone great changes. Sound is a kind of mechanical wave. Its effect on the optical fiber is to stress and bend the optical fiber. By bending, the sound intensity can be obtained. Compared with laser gyro, FOG has high sensitivity, small size, and low cost. It can be used in the high-performance inertial navigation systems of aircraft, ships, and missiles. Another major category of fiber optic sensors is the use of fiber optic sensors. The structure is rough as follows: The sensor is located at the end of the fiber. The fiber is just the transmission line of light, and the physical quantity to be measured is transformed into the change of the amplitude, phase, or amplitude of the light. In this sensor system, conventional sensors are combined with optical fibers. The introduction of optical fibers offers the possibility of implementing probing telemetry. This fiber-optic transmission sensor has a wide range of applications and is easy to use, but its accuracy is slightly lower than that of the first type of sensor. Fiber optic sensors have become a rising star in sensor families with their numerous advantages and have played their own unique role in various measurements and become an indispensable part of the sensor family. IV. Bionic SensorBionic sensorA bionic sensor is a new sensor using a new detection principle, which uses immobilized cells, enzymes, or other bioactive substances and transducers to form a sensor. This kind of sensor is a new type of information technology developed in recent years by the mutual penetration of biomedicine and electronics and engineering. This sensor is characterized by high performance and long life. In bionic sensors, biometric sensors are more commonly used. Bionic sensors in accordance with the media used can be divided into enzyme sensors, microbial sensors, organelle sensors, tissue sensors. In the picture, we can see that there is a close connection between the biomimetic sensor and all aspects of the biological theory and it is a direct result of the development of the biological theory. Among biosensors, urea sensors are a recently developed type of sensor. The following is an example of a urea sensor biosensor sensor application. The urea sensor is mainly composed of two parts, a biofilm, and an ion channel. The biofilm can feel the effects of external stimuli, the ion channel can receive the information of the biofilm and amplify and deliver it. When the sensory site inside the film is affected by an external stimulating substance, the permeability of the membrane will change, allowing a large number of ions to flow into the cell to form the transmission of information. Among them, the important component of the biofilm is the membrane protein, which can produce a conformal network change, change the permeability of the membrane, and transmit and amplify the information. The biofilm ion channels, which are composed of amino acid polymers, can be replaced by polymers of polyamine acids (L-glutamic acid, PLG), which are easily synthesized in organic chemistry, and are more chemically stable than the enzyme. PLG is water-soluble, which is not suitable for motor modification. However, PLG and polymer can synthesize block copolymers to form sensor films for sensors. The principle of the ion channel of the biofilm is basically the same as that of the biofilm. After the block copolymer film is fixed on the electrode, if a substance that changes the inductive network of the PLG is added, the permeability of the film changes, and thus a current is generated. Changes in the current from the changes can be carried out on the detection of stimulating substances. The urea sensor has been tested and proved to be a biometric analog sensor with good stability. The lower limit of detection is 10 orders of magnitude of a negative third power. It can also detect irritant substances, but for the time being it is not suitable for the measurement of living organisms. At present, although many biomimetic sensors have been developed successfully, the stability, reproducibility, and mass productivity of biomimetic sensors are obviously insufficient. Therefore, biomimetic sensing technology is still in its infancy. Therefore, in addition to continuing to develop a new series of biomimetic sensors And improve the existing series, the biomembrane immobilization technology and solid-state biomimetic sensor deserved further study. In the near future, biomimetic sensors that simulate the functions of the organism will appear, which may exceed the sensitivity of human facial features and improve the robot's vision, taste, touch, and ability to operate on objects. We can see the broad prospects for biomimetic sensor applications, but these require the further development of biotechnology, and we'll see this day coming. V. Infrared SensorInfrared sensorInfrared technology has been developed to the present, as we all know. This technology has been widely used in modern science and technology, national defense and agriculture, and other fields. Infrared sensing systems are infrared-based measurement systems that can be divided into five categories based on function:  (1) radiometers for radiation and spectroscopic measurements; (2) search and tracking systems for searching and tracking infrared targets, determining Its spatial position and its movement are tracked; (3) The thermal imaging system can produce a distribution image of the entire target infrared radiation; (4) Infrared ranging and communication systems; (5) Hybrid systems, refer to the above categories A combination of two or more in the system. Let us look at the composition of the infrared system, the main optical system, and auxiliary optical system, on the basis of which the key components of infrared are discussed in detail. In fact, the working principle of the infrared sensor is not complicated, the working principle of each part of a typical sensor system is as follows: (1)The target object. According to the infrared radiation characteristics of the target to be set, the infrared system can be set. (2)Atmospheric attenuation. When the target's infrared radiation passes through the Earth's atmosphere, the infrared radiation emitted by the infrared source will be attenuated due to the scattering and absorption of gas molecules and various gases, and various sol particles. (3) Optical receiver. It receives a portion of the target's infrared radiation and transmits it to the infrared sensor. Equivalent to a radar antenna, often used as an objective lens. (4) Radiation modulator. Radiation from the target under test is modulated into alternating radiant light to provide the target orientation information and to filter out large areas of interfering signals. Also known as a reticle and chopper, it has a variety of structures. (5) Infrared detector. This is the heart of the infrared system. It is the use of infrared radiation and the physical interaction between the physical effects of detecting infrared radiation sensors, in most cases is the use of this interaction presented by the electrical effects. Such detectors can be divided into two types of photon detectors and thermal detectors. (6) Detector cooler. Since some detectors must work at low temperatures, the corresponding system must have refrigeration equipment. After cooling, the equipment can shorten the response time and increase detection sensitivity. (7) Signal processing system. The detected signal is amplified, filtered, and extracted from these signals. This information is then converted into the required format and finally delivered to the control device or display. (8) Display device. This is the terminal device of the infrared device. Commonly used displays include oscilloscopes, kinescopes, infrared sensitized materials, indicating instruments, and recorders. Here gives a video of infrared sensors:Working principle of infrared sensorAccording to the above process, the infrared system can complete the measurement of the corresponding physical quantity. The infrared system is the core of infrared detectors, according to the detection mechanism of different, can be divided into two categories of heat detectors and photon detectors. The heat detector is used as an example to analyze the principle of the detector. The thermal detector is the use of radiant heat effect, so that the detection element causes the temperature to rise after receiving radiation, and thus makes the detector temperature-dependent performance changes. By detecting a change in one of these properties, radiation can be detected. In most cases, radiation is detected by thermoelectric changes. When the element receives the radiation and causes a non-electrical physical change, the corresponding change in the amount of electricity can be measured by appropriate transformation. Infrared sensors have played an important role in modern production practices. With the improvement of detection equipment and other parts of technology, infrared sensors can have more performance and better sensitivity. VI. Electromagnetic Sensor Magnetic sensors are the oldest sensors and compass is the earliest application of magnetic sensors. However, as a modern sensor, in order to facilitate the signal processing, a magnetic sensor is required to convert the magnetic signal into an electrical signal. The earliest applications were magnetoelectric sensors manufactured on the principle of electromagnetic induction. This magnetic sensor has made an outstanding contribution to industrial control. But today it has been replaced by a new type of magnetic sensor based mainly on high-performance magnetically sensitive materials.The shape of an electromagnetic sensorAmong the electromagnetic effect sensors used today, the magnetic rotation sensor is an important one. Magnetic rotation sensor mainly by the semiconductor magnetoresistive components, permanent magnets, fixtures, enclosures, and other components. A typical structure is a pair of magnetoresistive elements mounted on a permanent magnet stimulation, the input and output terminals connected to the fixture, and then installed in the metal box, and then sealed with plastic to form a closed structure, the structure has good reliability. Magnetic rotation sensor has many advantages of semiconductor magnetoresistance element. In addition to having high sensitivity and a large output signal, it also has a strong speed detection range, which is due to the development of electronic technology. In addition, this sensor can also be used in a wide temperature range, has a long working life, resistance to dust, water, and oil, and therefore withstand a variety of environmental conditions and external noise. Therefore, this kind of sensor has received widespread attention in industrial applications. Magnetic rotary sensors are widely used in factory automation systems because they have satisfactory characteristics and do not require maintenance. Its main application is the machine tool servo motor rotation detection, factory automation robotic arm positioning, hydraulic stroke detection, factory automation related equipment position detection, rotary encoder detection unit, and a variety of rotating detection unit. Modern magnetic rotation sensors mainly include four-phase sensors and single-phase sensors. In the course of work, four-phase differential rotation sensor with a pair of detection unit to achieve differential detection, the other to achieve the inverted differential detection. In this way, four-phase sensor detection capability is four times single-element. The two-element single-phase rotation sensor also has its own advantages, that is, small and reliable features, and the output signal can detect low-speed movement, anti-environmental impact, and anti-noise ability, low cost. Therefore, single-phase sensors will also have a good market. Magnetic rotary sensors also have great potential for use in household appliances. In the reversing mechanism of the cassette recorder, a magnetic resistance element can be used to detect the end of the magnetic tape. Most home video recorders have a variable speed and high-speed playback function, which can also be used magnetic spindle sensors to detect the spindle speed and control, to obtain a high picture quality. The positive and negative rotation of the motor in the washing machine and the high and low-speed rotation functions can be detected and controlled by the servo rotation sensor. Electromagnetic proximity switch. This switch can be sensed into the metal area of their own test objects, control their own internal circuit on or off. The switch generates its own magnetic field. When a metal object enters the magnetic field, it will cause a change in the magnetic field. This change can be turned into an electrical signal by switching the internal circuitry. The electromagnetic sensor is a widely used high-tech, both at home and abroad have invested some research efforts in research, the application of this sensor is penetrating into the national economy, national defense construction and people's daily life in all fields, with the information The arrival of society, its status and role will certainly be more prominent. VII. Magneto-optical Effect SensorMagneto-optical effect sensorModern electric measurement technology is maturing day by day, has the advantages of high precision, easy to real-time processing connected to a microcomputer, etc., has been widely used in the measurement of electrical and non-electrical measurements. However, the electrical measurement method is susceptible to interference. In the AC measurement, the frequency response is not wide enough and there are certain requirements on voltage and insulation. With the rapid development of laser technology, the above problems have been solved. Magneto-optic effect sensors are high-performance sensors using laser technology. Laser is another new technology that has been rapidly developed in the early 1960s. Its appearance signals that people have mastered and utilized light waves and entered a new stage. Due to the low monochromaticity of ordinary light sources in the past, many important applications are limited. The advent of lasers makes radio technology and optical technology by leaps and bounds, penetrate each other and complement each other. Today, many sensors have been fabricated using lasers that solve many of the unsolved technical problems that make them suitable for use in hazardous, flammable places such as coal, oil, and gas storage. For example, optical fiber sensors made of laser can measure the situation of crude oil injection, cracking oil tank parameters. It is not necessary to supply power at the place of measurement. This is particularly applicable to the petrochemical equipment group that requires strict safety and explosion protection measures. It can also be used to implement optical method telemetry chemistry in some aspects of large-scale steel plants. The principle of magneto-optic effect sensor mainly utilizes the polarization state of light to realize the function of the sensor. When a beam of polarized light passes through the medium, if there is an external magnetic field in the beam propagation direction, the light will rotate through the plane of polarization by an angle, which is the magneto-optical effect. That is, the applied magnetic field can be measured by the angle of rotation. Under certain experimental setups, the angle of deflection is proportional to the intensity of the output, and the laser diode LD is illuminated by the output light to obtain the digitized light intensity that is used to measure a particular physical quantity.Magneto-optical effect sensorSince the late 1960s, RC Lecraw has raised great concerns after his research report on magneto-optical effects was presented. Japan, the Soviet Union, and other countries have conducted research, and domestic scholars have also explored it. Magneto-optical sensor with excellent electrical insulation properties and anti-interference, wide frequency response, safety, and explosion-proof and other characteristics, and therefore for some special occasions electromagnetic parameters of measurement, has a unique effect, especially in the power system high voltage and current The measurement aspect shows its potential advantages. At the same time, by developing the software and hardware of the processing system, automatic real-time measurement of the welding machine and the robot control system can also be realized. In the use of magneto-optic effect sensors, the most important thing is to choose magneto-optical media and lasers. Different devices have different capabilities in terms of sensitivity and working range. With the advent of high-performance lasers and new types of magneto-optical media in recent decades, the performance of magneto-optical effect sensors has become stronger and the applications have become more widespread. Magneto-optical sensor, as a specific purpose sensor, can play its own function in a particular environment. It is also a very important industrial sensor.  VIII. How to Choose Industrial SensorsModern sensors vary widely in principle and structure. How to select a sensor based on a specific measurement purpose, measurement object, and measurement environment is the first problem to be solved when performing a certain amount of measurement. When the sensor is determined, the matching measuring method and measuring equipment can be determined. The success or failure of measurement results depends to a large extent on the reasonableness of the choice of sensors. The influencing factors are:  (1) Determine the type of the sensor according to the measurement object and the measurement environment. (2)Selection of the sensitivity. (3)Frequency response. (4) Linear range. (5)Stability.(6) Accuracy. FAQ 1. What sensor means?a device that responds to a physical stimulus (such as heat, light, sound, pressure, magnetism, or a particular motion) and transmits a resulting impulse (as for measurement or operating a control) .2. What is the purpose of a sensor?A sensor converts the physical action to be measured into an electrical equivalent and processes it so that the electrical signals can be easily sent and further processed. The sensor can output whether an object is present or not present (binary) or what measurement value has been reached (analog or digital). 3. How do sensors work?Put simply, a sensor converts stimuli such as heat, light, sound and motion into electrical signals. These signals are passed through an interface that converts them into a binary code and passes this on to a computer to be processed. 4. What can sensors detect?Broadly speaking, sensors are devices that detect and respond to changes in an environment. Inputs can come from a variety of sources such as light, temperature, motion and pressure. 5. What are the importance of sensors in our daily life?Intelligent sensor systems are omnipresent in our everyday lives. They provide security, save lives and improve our quality of life. As more and more areas of life are automated and networked, the importance of innovative sensor technologies will also increase in the future. 6. How do we classify sensors?Classification of Sensors:Active and Passive Sensors. Contact and Non-Contact Sensors.Absolute and Relative Sensors.Analog and Digital Sensors.Miscellaneous Sensors. 7. How are sensors used to collect data?With a sensor, a machine observes the environment and information can be collected. A sensor measures a physical quantity and converts it into a signal. Sensors translate measurements from the real world into data for the digital domain. 8. What is the difference between sensor and transducer?The main difference between sensor and transducer is that a transducer is a device that can convert energy from one form to another, whereas a sensor is a device that can detect a physical quantity and convert the data into an electrical signal. 9. Why do we need a temperature sensor?Within our homes, temperature sensors are used in many electrical appliances, from our refrigerators and freezers to help regulate and maintain cold temperatures as well as within stoves and ovens to ensure that they heat to the required levels for cooking, air confectioners/heaters. 10. How sensors are connected?A sensor device directly connected to a computer. A connected sensor is a sensor that also has a way to send data to either a local network or the Internet. Diagram of a sensor receiving waves on the left and broadcasting a wireless signal on the right to a router. A sensor device wirelessly connected to a network. 11. Can a transducer be a sensor?A Sensor is defined as a device which measures a physical quality (light, sound, space) and converts them into an easily readable format. If calibrated correctly, sensors are highly accurate devices. Not all transducers are sensors but most sensors are transducers. 12. What is the difference between active and passive sensors?Active sensors have its own source of light or illumination. In particular, it actively sends a pulse and measures the backscatter reflected to the sensor. But passive sensors measure reflected sunlight emitted from the sun. When the sun shines, passive sensors measure this energy. 13. What are the basic characteristics considered in the process of sensor selection?Sensor selection criteria include temperature, size, protection class, and whether the sensor requires a discrete or analog input. Also consider sensor repetition accuracy, sensor response speed, and sensing range. 14. What are the applications of sensors?Sensors are central to industrial applications being used for process control, monitoring, and safety. Sensors are also central to medicine being used for diagnostics, monitoring, critical care, and public health. 15. How do you check the accuracy of a sensor?To find out the accuracy of sensor you have to take several readings by your sensor on that particular one input parameter (like. temperature). after accumulating those sensor output values evaluate the standard deviation as per law, which indicate the accuracy level of your sensor. You May Also Like GPS and inertial sensors for driverless applicationsA New Technology for Advancing Opticals,Sensors Even Resistant SupercapacitorsSensors are Always In a State of Rapid ProgressComprehensive Analysis of Fiber Optic Sensor 

  Light emitting diode (LED) is a light source that meets the requirements of green lighting. LEDs are safe, efficient, environmentally friendly, long-lived, responsive, small in size and robust in construction with many features that are unmatched by ordinary light-emitting devices. Moreover, it is one of the first semiconductor devices and is widely used. Currently, LEDs are widely used as indicators for various electronic products and as light sources for fiber optic communication.     How dose a diode work?     Catalog I What is a diode? II How dose a diode work? III What is diode characteristics? IV What are diode parameters? V What are the types of diodes? FAQ   I What is a diode?   Diode is an electronic device made of semiconductor materials (silicon, selenium, germanium, etc.) . It has a unidirectional conductivity, that is, the diode anode and cathode to add a forward voltage, the diode conducts. When the reverse voltage is added to the anode and cathode, the diode cuts off. Therefore, the on and off of the diode is equivalent to the on and off of the switch.   In almost all electronic circuits, semiconductor diodes are used. The use of semiconductor diodes in the circuit can play a role in protecting the circuit, extending the life of the circuit. The development of semiconductor diodes has made integrated circuits more optimized and has played an active role in various fields. Diodes have many roles in integrated circuits and maintain the proper functioning of the integrated circuits.     Diodes were one of the first semiconductor devices to be created, and their applications are very widespread. Especially in a variety of electronic circuits, the use of diodes and resistors, capacitors, inductors and other components to make a reasonable connection to form a circuit of different functions, you can achieve a variety of functions such as rectification of alternating current, detection of modulated signals, limiting and clamping, and voltage regulation of the supply voltage. Whether in common radio circuits or in other household appliances or industrial control circuits, diodes can be found.   A diode is made of a PN junction with corresponding electrode leads and a tube housing package. The diode has two electrodes, the electrode leading from the P area is the positive electrode, also known as the anode; the electrode leading from the N area is the negative electrode, also known as the cathode.       Diode structure         There are many kinds of diodes:  - According to the semiconductor materials used, they can be divided into germanium diodes and silicon diodes.   - According to their different uses, they can be divided into detector diodes, rectifier diodes, zener diodes, switching diodes, etc.   - According to the structure of the tube core, they can be divided into point-contact diodes, surface-contact diodes and planar diodes.     --  The point contact diodes are pressed on the smooth surface of the semiconductor wafer with a thin metal wire. With pulse current, one end of the contact wire is sintered firmly with the wafer to form a "PN junction". Due to point contact, only small currents (no more than a few tens of mA) are allowed, which is suitable for high frequency low current circuits, such as radio detection, etc. The area of "PN junction" of surface contact diode is large, which allows large currents passing through and is mainly used in "rectifying" circuits that convert AC to DC.    --  Planar diode is a kind of special silicon diode. It not only can pass through large current, but also has stable and reliable performance. It is widely used in switching, pulse and high frequency circuits.   II How does a diode work? The crystal diode is a p-n junction formed by p-type semiconductor and n-type semiconductor. It forms a space charge layer on both sides of the interface and has a self-built electric field. When there is no applied voltage, the diffusion current caused by the carrier concentration difference on both sides of the p-n junction is equal to the drift current caused by the self-built electric field, so it is in an electric equilibrium state. When the external positive voltage is biased, the mutual suppression of the external electric field and the self-built electric field results in the increase of the carrier diffusion current, which is shown in the conduction region below. When the external reverse voltage is biased, the external electric field and the self-built electric field are further strengthened to form a reverse saturation current I0 independent of the reverse bias voltage value within a certain reverse voltage range, which is shown in the cut-off region below. When the applied reverse voltage is high enough to a certain extent, the electric field intensity in the space charge layer of p-n junction reaches the critical value to produce the multiplying process of the carriers, resulting in a large number of electron hole pairs and a numerical reverse breakdown current is generated, known as the diode breakdown, which is shown in the breakdown region below. III What is diode characteristics? The most important characteristic of the diode is the unidirectional conductivity. In the circuit, the current can only flow from the positive electrode of the diode, and flows out from the negative electrode . The forward and reverse characteristics of the diode are illustrated by simple experiments.   3.1 Forward characteristics In electronic circuits, if the diode is connected to the high potential terminal and the negative electrode to the low potential terminal, the diode will be switched on. This connection is called forward bias. It must be noted that when the forward voltage applied to both ends of the diode is very small, the diode still cannot be switched on, and the forward current flowing through the diode is very weak. Only when the forward voltage reaches a certain value (about 0.6 V of the silicon tube) can the diode be truly switched on. The voltage at both ends of the diode after conduction is called the forward voltage drop of the diode.   3.2 Reverse characteristic In the electronic circuit, the positive end of the diode is connected to the low potential end, the negative electrode is connected to the high potential terminal, and the diode is in the cutoff state. This mode of connection is called reverse bias. When the diode is in reverse bias, there will still be a weak reverse current flowing through the diode, called leakage current. When the reverse voltage of the diode increases to a certain value, the reverse current will increase sharply, and the diode will lose the single direction conduction characteristic. This state is called the breakdown of diode.   IV What are diode parameters? The technical specifications used to test the performance of diodes are called diode parameters. Here are some of the main parameters in diode testing:   4.1 Rated forward working current (IF) Refers to the maximum forward current that is allowed to pass through the diode when it is in continuous operation over a long period of time. When a larger current passes through the diode, the dice is heated and the temperature rises, and when the temperature exceeds the allowable limit, the dice is overheated and damaged. Therefore, it should not exceed the diode rated forward operating current value when the diode is in use. Eg. The rated forward working current of DFM is 1A   4.2 Forward Voltage(VF) Refers to the voltage at both ends of the diode when the rated forward working current IF is passed through the diode. Eg. The voltage at both ends of the diode is about 0.9V when the forward working current of DFM is 1A.   4.3 Maximum reverse operating voltage (VR) When the reverse voltage at both ends of the diode is raised to a certain value, the diode will be broken down and the unidirectional conductivity will be lost. In order to ensure the safety of operation, the maximum reverse operating voltage is specified. Eg. The maximum reverse operating voltage of DF10M is 1100V and the breakdown voltage is about 1400V   4.4 Reverse current IR Refers to the reverse current that flows through the diode when the maximum reverse operating voltage VR is applied to both ends of the diode. The smaller the reverse current, the better the unidirectional conductivity of the diode will be. Eg. When the reverse voltage of DF10M is 1100V, the VR is about 0.2uA.   4.5 Reverse critical current (IZ) Refers to the reverse current of the diode increases sharply to close to the breakdown phenomenon.   Eg. Set the IZ of DF10M to 0.1 Ma (Ma) 4.6 Reverse critical voltage (VZ) Refers to the reverse voltage of the diode when the reverse current is IZ. If the reverse voltage is greater than this value, the reverse current increases dramatically and the unidirectional conductivity of the diode is destroyed, thus causing reverse breakdown. Eg. The VZ is about 1300V when IZ of DF10M is 0.1mA.   4.7 Reverse recovery time (Trr) When diodes are in low frequency applications, it generally do not need to consider its conduction to the cut-off, or cut-off to the transition time. But if the diode works in a high-speed switching circuit environment, when diode suddenly turns to reverse bias from the forward biased conduction state, it will take a certain time to become a cut-off state, which is called reverse recovery time. But if the diode works in a high-speed switching circuit environment, when diode suddenly turns to reverse bias from the forward biased conduction state, it will take a certain time to become a cut-off state, which is called reverse recovery time. Eg. The maximum Trr of EDF1DM is 50nS.   V What are the types of diodes?   5.1 Light emitting diode Light emitting diode, also called LED, is a semiconductor diode that converts electrical energy into luminous energy. Like ordinary diodes, LEDs are made up of a PN junction and have unidirectional conductivity. When a forward voltage is applied to a light-emitting diode, Holes injected from P region to N region and electrons injected from N region to P region are recombined with N region electrons and P region holes in several microns near PN junction to produce spontaneous emission fluorescence.    The energy states of electrons and holes in different semiconductor materials are different. When electrons and holes are combined, the energy released is different. The more energy is released, the shorter the wavelength of light is. The commonly used diodes are red, green or yellow light.The reverse breakdown voltage of a light-emitting diode is greater than 5 volts. Its forward volt-ampere characteristic curve is so steep that it must be used in series to control the current passing through the diode. The current limiting resistance R can be calculated by the following formula: R=（E－UF）/IF . In this formula, E is the power supply voltage, UF is the forward voltage of LED, IF is the running current of LED.   5.2 Zener diode Zener diode, is also called voltage stabilizing diode. By using the reverse breakdown state of pn junction, the current can be changed in a wide range and the voltage is basically unchanged, thus form a diode which has voltage stabilizing function. This diode is a semiconductor device with high resistance until it reaches the critical reverse breakdown voltage.  The following picture is a typical Zener diode application circuit diagram: At this critical breakdown point, the reverse resistance is reduced to a very small value, where the current increases and the voltage remains constant in this low resistance region, and the Zener diode is divided according to the breakdown voltage, because of this characteristic, The regulator is mainly used as a voltage regulator or voltage reference element. Zener diodes can be connected in series for use at higher voltages, and higher stable voltages can be obtained by serializing them.   5.3 Switching diode  Working principle: The semiconductor diode is equivalent to switch-on when it is turned on (the circuit is turned on), and is equivalent to switch-off when it is turn-off (the circuit is cut off), so the diode can be used as a switch. The common used model is 1N4148. Due to the unidirectional conductivity of semiconductor diodes, the PN junction is on at positive bias, and the resistance is very small at the on-state, which ranges from tens to hundreds of ohs. At reverse bias, it is in a cut-off state, and its resistance is very large. Generally, silicon diodes are above 10 μ Ω and germanium diodes have tens to hundreds of kilos. By using this property, the diode will play the role of controlling the current on or off in the circuit and become an ideal electronic switch.   At high frequency, the barrier capacitance of the diode exhibits extremely low impedance and is parallel to the diode. When the capacitance of the barrier itself reaches a certain level, the switching performance of the diode will be seriously affected. In extreme conditions, the diode will be short-circuited, and the high-frequency current will no longer pass through the diode, but will pass directly through the barrier capacitance, and the diode will fail to work. The barrier capacitance of the switching diode is generally small, which is equivalent to blocking the barrier capacitance path and achieving the effect of maintaining good unidirectional conductivity at high frequency.  Classification: General switching diode, high speed switching diodes, ultra-high speed switching diodes, low-power switching diodes, high reverse voltage switching diodes, silicon voltage switching diodes and so on.   5.4 Variable capacitance diode( Varactor Diodes ) Variable capacitance diode, also known as varactor Diodes, are semiconductors that change the junction capacitance according to the voltage supplied. That is, as variable capacitors, they can be used in resonant circuits such as FM tuners and TV tuners and FM modulation circuits. Working principle: Varactor Diodes is a kind of special diode. When applied forward bias voltage, the depletion region of PN (positive and negative electrode) junction is narrowed and the capacitance becomes larger, which results in diffusive capacitance effect. However, the leakage current will be generated when the forward bias is added, so the reverse bias is supplied in application. In fact, we can think of it as a PN junction. If a reverse voltage V is added to the PN junction (the varactor diode is used in reverse direction), the electrons in the N-type semiconductor are directed to the positive electrode and holes in P-type semiconductor will be led to the negative electrode. Then forms a depletion layer that has neither electrons nor holes, and the width of the depletion layer is set to d, which changes with the reverse voltage V. In this way, when the reverse voltage V increases, the depletion layer d becomes wider and the diode capacitance C decreases (according to C=kS/d), and the reverse voltage decreases, the depletion layer width d becomes narrower and the diode capacity becomes larger. The change of reverse voltage V leads to the change of depletion layer, which changes the junction capacity of the variable capacitance diode. - Application: the varactor diode is a semiconductor device based on the principle of variable capacitance between PN junctions. It is used as a variable capacitor in high frequency tuning and communication circuits. As shown in the following figure, the reverse voltage of the diode is changed by changing the different R2. This will result in a change in the capacitance of the diode, thus changing the resonant frequency in which the varactor diode can pull out the full range of the required capacitance in the parallel resonant band-pass filter.   FAQ   1. What is diode and its symbol? Diode, an electrical component that allows the flow of current in only one direction. In circuit diagrams, a diode is represented by a triangle with a line across one vertex.   2. What is special about a diode? Some semiconductor junctions, composed of special chemical combinations, emit radiant energy within the spectrum of visible light as the electrons change energy levels. Simply put, these junctions glow when forward biased. A diode intentionally designed to glow like a lamp is called a light-emitting diode, or LED.   3. Are diodes AC or DC? It allows current to flow easily in one direction, but severely restricts current from flowing in the opposite direction. Diodes are also known as rectifiers because they change alternating current (ac) into pulsating direct current (dc). Diodes are rated according to their type, voltage, and current capacity.   4. Why do we use zener diode? Zener diodes are used for voltage regulation, as reference elements, surge suppressors, and in switching applications and clipper circuits. The load voltage equals breakdown voltage VZ of the diode. The series resistor limits the current through the diode and drops the excess voltage when the diode is conducting.   5. What is unit of diode? A diode is not a measurable quantity. Hence,it does not have a unit. Generally,for a diode,we measure characteristics like forward voltage drop,reverse voltage drop and reverse breakdown voltage which are usually measured in Volts.   6. Do diodes have resistance? Just like a resistor or any other load in a circuit, a diode offers resistance in a circuit. Unlike resistors, though, diodes are not linear devices. This means that the resistance of diodes does not vary directly and proportional to the amount of voltage and current applied to them.   7. Does diode reduce current? Ideally, diodes will block any and all current flowing the reverse direction, or just act like a short-circuit if current flow is forward. Unfortunately, actual diode behavior isn't quite ideal. Diodes do consume some amount of power when conducting forward current, and they won't block out all reverse current.   8. How are diodes classified? Diodes are classified according to their characteristics and are offered in a number of different types, including rectifiers, switching diodes, Schottky barrier diodes, Zener (constant voltage) diodes, and diodes designed for high-frequency applications.   9. What is the most common diode? The most commonly used signal diode is the 1N4148. This diode has a close brother called 1N914 that can be used in its place if you can't find a 1N4148. This diode has a forward-voltage drop of 0.7 and a peak inverse voltage of 100 V, and can carry a maximum of 200 mA of current.   10. What is the difference between a Zener diode and a Schottky diode? As their switching speed is very high, Schottky diodes recover very fast when the current reverses, resulting in only a very small reverse current overshoot. ... A special type of diode, called the Zener diode, blocks the current through it up to a certain voltage when reverse biased.   11. What is difference between Schottky diode and normal diode? In the normal rectifier grade PN junction diode, the junction is formed between P type semiconductor to N type semiconductor. Whereas in Schottky diode the junction is in between N type semiconductor to Metal plate. The schottky barrier diode has electrons as majority carriers on both sides of the junction.   12. Why it is called diode? A diode is called a diode because it has two distinct electrodes (i.e. terminals), called the anode and the cathode. A diode is electrically asymmetric because current can flow freely from the anode to the cathode, but not in the other direction. In this way, it functions as a one-way valve for current.   13. Is a diode the same as a resistor? Key Difference: A diode is a type of electrical device that allows the current to move through it in only one direction. ... A resistor is an electric component that is used to provide resistance to current in the circuit. They are mostly used to produce heat or light.   14. How much voltage can a diode take? Silicon diodes have a forward voltage of approximately 0.7 volts. Germanium diodes have a forward voltage of approximately 0.3 volts. The maximum reverse-bias voltage that a diode can withstand without “breaking down” is called the Peak Inverse Voltage, or PIV rating.   15. Can a resistor replace a diode? Diodes only conduct in one direction whereas resistors conduct in both directions. Without analyzing the actual circuit the results would be unpredictable but, generally speaking, being that diodes & resistors are designed to do different things, substituting one for the other is something you wouldn't want to do.  

Warm hints: The word in this article is about 2500 and  reading time is about 12 minutes. The fiber optic sensor consists of the light source, incident fiber, exit fiber, light modulator, light detector, and demodulator. The basic principle is that the light of the light source is sent to the modulation area through the incident optical fiber, and the light interacts with the measured parameters in the modulation area to change the optical property of the light into the modulated signal light which is then sent through the outgoing fiber optical detector, demodulator and get the measured parameters. In recent years, sensors have evolved in the direction of sensitivity, precision, adaptability, compactness, and intelligence.  Optical fiber has many excellent properties, such as anti-electromagnetic interference and atomic radiation performance, soft and lightweight mechanical properties. Insulation, non-responsive electrical properties. Water, heat, and corrosion resistance of chemical properties, can reach people's eyes and ears in unattainable places (such as high-temperature areas), or in areas harmful to humans (such as nuclear radiation area), but also can transcend human physiological boundaries and receive sensory organs Unexpected outside information.   Catalogs I. Basic Structure and Principle of Fiber Optic SensorII. Application of Light Sensor in Petrochemical Industry2.1 The application of fiber optic sensor in the   petrochemical system2.2 The application of fiber optic sensor in oil   loggingIII. Application of Fiber Optic Sensors in Power Systems3.1 Applications in the high voltage cable temperature   and strain measurement3.2 Application in Electric Power Sensors3.3 Application of optical fiber cable monitoringIV. Fiber Optic Sensors in Medical Applications4.1 Pressure measurement4.2 Blood flow velocity measurement4.3 PH measurementV. Fiber Optic Sensor FeaturesFAQ  I. Basic Structure and Principle of Fiber Optic Sensor The fiber optic sensor consists of the light source, incident fiber, exit fiber, light modulator, light detector, and demodulator. The basic principle is that the light of the light source is sent to the modulation area via the incident fiber, and the light interacts with the measured parameters in the modulation area to make the optical properties (such as intensity, wavelength, frequency, phase, and normality) of the light occur Changes into a modulated signal light, and then sent through the optical fiber into the optical detector, demodulator to obtain the measured parameters. Fiber optic sensors can be divided into two categories by sensing principle: one is the light transmission (non-functional type) sensor, the other is the sensor type (functional) sensor. In the fiber optic sensor, the optical fiber only as a light transmission medium, the measured signal is detected by other sensitive components, this exit fiber, and the incident optical fiber is not continuous. Between the two Modulators are spectrally sensitive or other types of sensitive elements. In the sensing type fiber optic sensor, the optical fiber has both the sensitivity to the signal to be measured and the transmission of the optical signal. And the "sense" and "pass" of the signal are combined so that the optical fiber in such a sensor is continuous. Due to the different roles played by the optical fibers in these two sensors, the requirements for the optical fibers are also different. Optical fiber in the light-transmitting sensor only plays the role of light transmission. The use of communication fiber even ordinary multi-mode fiber can meet the requirements, and sensitive components can be a very flexible selection of high-quality materials. So the sensitivity of these sensors needs more optical coupling devices, the structure is more complex. The structure of sensing type fiber optic sensor is relatively simple with fewer coupling devices, but higher requirements on the optical fiber. It often needs to be sensitive to signal measurement, with good transmission characteristics. So far, most people adopt the former, but with the improvement of optical fiber manufacturing technology, sensor-type fiber optic sensors will also be widely used. According to the principle of light being modulated in optical fiber, fiber optic sensors can be divided into intensity modulation, phase modulation, polarization modulation, frequency modulation, wavelength modulation, and so on. Up to now, optical sensors have been able to measure more than 70 physical quantities. Fiber Optic Sensors have unique advantages over traditional sensors. (1) High sensitivity. Since light is a very short wavelength electromagnetic wave, its optical length is obtained by the phase of light. Taking an optical fiber interferometer as an example, due to the small diameter of the fiber used, its optical length is subject to slight mechanical external force or temperature change, causing a large phase change. Suppose that with a 10-meter optical fiber, a change of 1 ° C causes a phase change of 1000ard. If the minimum phase change that can be detected is 0.01ard, the minimum change in temperature that can be measured is 10 ° C, showing a high sensitivity. (2) Anti-electromagnetic interference, electrical insulation, corrosion resistance, intrinsically safe. Since fiber optic sensors transmit information using light waves, optical fibers are an electrically insulating, corrosion-resistant transmission medium and safe, which makes it easy and effective to use All kinds of large electromechanical, petrochemical, mine and other strong electromagnetic interference and flammable and explosive and other harsh environments. (3) Fast measurement. Light travels fastest and can transmit two-dimensional information, so it can be used for high-speed measurements. The analysis of radar and other signals requires an extremely high detection rate. The application of electronics is difficult to achieve. Using high-speed spectral analysis of light diffraction can be solved. (4) Large information capacity. The signal under test is a light wave carrier, and the light has a very high frequency. The contained frequency band is very wide. The same optical fiber can transmit multiple signals. (5) Suitable for harsh environments. Optical fiber is a dielectric, high voltage, corrosion-resistant, anti-electromagnetic interference that can be used for other sensors that do not adapt to the harsh environment. In addition, fiber-optic sensors are also characterized by their lightweight, small size, flexibility, wide measurement range, good reusability, and low cost. The application of fiber optic sensors is precise because fiber optic sensors have so many advantages, making it a very wide range of applications, involving petrochemicals, power, medicine, civil engineering, and many other fields. Video 1 Introduction of fiber optic sensorsII. Application of Light Sensor in Petrochemical Industry 2.1 The application of fiber optic sensor in the petrochemical systemIn the petrochemical system, due to the underground environment with high temperature, high pressure, chemical corrosion and electromagnetic interference, and other characteristics, the conventional sensor is difficult to play a role in the well. However, the fiber itself is no charge, small and light, easy to bend, anti-electromagnetic interference, and anti-radiation performance. Particularly it is suitable for flammable and explosive, strict restrictions and strong electromagnetic interference, and other harsh environments. Fiber optic sensors in the measurement of the good parameters play an irreplaceable role. It will become the oil and gas exploration and oil logging and other logging A field of broad market prospects of new technologies.  Fiber optic sensor application in oil and gas exploration. Because of its high-temperature capability, multi-communications, distributed sensing capabilities, and the fact that it requires only a small space to meet its use conditions, fiber optic sensors make it particularly unique in exploration drilling. The application of fiber optic sensors can be made into the downhole spectrometer, distributed temperature sensor, and optical fiber pressure sensor, and other products suitable for this special job requirement. (1) The downhole spectrometer fluid analyzer shown in Figure 1 can be used to understand the crude oil composition during the initial development process. It consists of two sensors: one is the absorption spectroscopy fiber and the other is the fluorescence and gas detector. Downhole fluid is introduced into the tubing by formation probes and the optical sensor is used to analyze the fluid within the tubing. Fluid analysis spectrometers provide in-situ downhole fluid analysis and improve formation fluid evaluation. (2) Distributed temperature sensors. Optical fiber distributed temperature sensors are the most popular fiber optic sensors for downhole applications. The application example is to monitor the steam injection heavy oil recovery system. Steam is injected into the heavy oil reservoir to reduce the viscosity of the oil, allowing heavy oil to be mined out. Downhole steam temperature can be as high as 250 ℃. Figure 1 Fluid analyzer structure(3) The fiber-optic pressure sensor is currently under development. Its main focus is on ultra-high temperature and downhole pressure monitoring tasks. Other commercial products based on fiber optic sensors are currently available. For example, fiber optic probes for multiphase flow measurements and distributed dynamic strain measurements. Its high reliability, high efficiency, and low power consumption are key factors in the success of optical fiber products in oil field applications. 2.2 The application of fiber optic sensor in oil loggingOil logging is one of the most basic and key aspects of the petroleum industry. The parameters such as pressure, temperature, and flow rate are important physical quantities in oil and gas wells. These advanced technologies are used for long-term Real-time monitoring, timely access to the information of oil and gas wells, the oil industry has a very important significance. Fiber optic sensors are insensitive to electromagnetic interference and withstand extreme conditions, including high temperatures and pressures, as well as strong shock and vibration, to measure borehole and well site environmental parameters with high accuracy, and have distributed measurement capabilities for fiber optic sensors. The spatial distribution gives the profile information. Moreover, the fiber optic sensor cross-sectional area is small, short in shape, in the wellbore occupies a very small space. Traditional electronic sensors do not have such features in the harsh underground environment. Fiber optic sensors can do downhole flow measurement, temperature measurement, pressure measurement, water (gas) measurement, density measurement, acoustic measurement. (1) Flow measurement. Because the intensity, phase, frequency, wavelength, and other characteristics of light in the optical fiber transmission process will be subject to flow modulation. A certain light detection method can convert the modulation into electrical signals, you can find the fluid flow, which is the fiber flow the working principle of the meter. (2) Temperature and pressure measurement. The distributed optical fiber measurement system (DTS) utilizes the Raman effect of the optical fiber to enable real-time monitoring of the temperature field where the fiber is located. The EFPI type (non-intrinsic FP interference) and FBG fiber optic sensors are wavelength-coded sensors. With high sensitivity, it also can simultaneously measure pressure, temperature, stress, and other parameters of the characteristics. The optical fiber thermal color temperature sensor is a reflective temperature sensor composed of a white light source and a multi-mode optical fiber.  The optical fiber radiation temperature sensor utilizes black body radiation energy. Its non-contact, measurable instantaneous temperature, fast response, and no need for heat balance time are available. In high-temperature measurement, the semiconductor absorption-type optical fiber temperature sensor utilizes the characteristic that the absorption edge wavelength of its semiconductor material shifts to a longer wavelength as the temperature increases, and an appropriate semiconductor light-emitting diode is selected so that its spectral range falls exactly on the absorption edge region. , So the light intensity through the semiconductor decreases with increasing temperature. (3)Water (Gas) Rate and transmission power of U-shaped fiber used for density measurement vary with the refractive index of the external medium. The lightwave serves as an information carrier and has nothing to do with the resistivity, flow pattern, and water quality of the mixed fluid. The fiber holding rate is based on this principle. The density sensor essentially solves the problem of the application of high water content without resolution and radioactive substances in the existing holding ratios. For the multi-phase fluids, the refractive indices of oil, water, and gas are all different, so the refractive index of the mixed fluid will follow. Change the ratio of oil, water, gas changes. Therefore, this refractive index modulation type fiber optic sensor can not only measure the fluid holding rate, fluid density can be measured at the same time, for its accuracy is higher. (4) Sonic measurement. Seismic waves propagate in different media and the waveforms of the received seismic waves will be different. According to different seismic waveforms, the sedimentary sequence and sedimentary structure can be identified to locate the reservoir, determine the gutter, detect the damage and fracture of the casing, and perforation, detect layers and determine the fluid flow, and so on. VSP seismic logging means that the geophone is placed in a well and the seismic signal is received by the geophone in the well by means of a micro-vibration generated by ground-derived seismic waves or fluid flow in the well.  The permanent downhole optical fiber three-component seismic survey has high sensitivity and directionality can produce high-precision spatial images. It can not only provide near-borehole images but also can provide strata images around the wellbore. And the measurement range can reach thousands of kilometers. It withstands harsh environmental conditions and has no moving parts and downhole electronics that can withstand strong shocks and vibrations and Can be installed in an extremely small space for complex completion string.  III. Application of Fiber Optic Sensors in Power Systems Because of the complicated structure and wide distribution of power system networks, various hidden dangers exist on the high-voltage power line and power communication network. Therefore, it is very important for distributed monitoring of various lines and networks in the system.  3.1 Applications in the high voltage cable temperature and strain measurementAt present, foreign countries (mainly Britain, Japan, etc.) have developed the distributed optical fiber temperature sensor products by utilizing the laser Raman spectroscopy effect. And domestically, we are actively carrying out research work in this area. The domestic begin to introduce the distributed optical fiber temperature sensing technology into the power system cable temperature measurement. In connection with the snow disasters suffered in southern China last year, we can consider that if we can lay sensor fiber optic cables in parallel on high-voltage cables and measure the temperature, pressure, and other parameters of power system cables and towers in real-time, we can make timely measurements, so as to minimize economic losses.  Fiber optic sensors in the power system will have a wide range of applications. Ideally, the fiber should be placed as close as possible to the cable core to more accurately measure the actual cable temperature. For direct-buried power cables, although the surface-mount fiber can not accurately reflect the change of cable load, it is more sensitive to the change of thermal resistivity of soil in the buried cable and can reduce the installation cost of optical fiber. 3.2 Application in electric power sensorsElectric power is the basic power reflecting the energy conversion and transmission in the power system. Electric power measurement is an important part of power metering. With the rapid development of the power industry, traditional electromagnetic measurement methods have increasingly exposed their inherent limitations, such as electrical insulation, electromagnetic interference, and magnetic saturation.  Therefore, people have been working hard to find new methods for measuring electrical power. It can be said that the advent of fiber optic sensors has brought people the gospel to solve this problem. The main characteristics of fiber-optic power sensors are: Since electric power sensing involves both voltage and current at the same time, it is usually necessary to consider both electro-optic and magneto-optic effects. At the same time, two kinds of sensing media or one multifunctional media are used as sensitive elements. The structure of the fiber electric power sensor head is relatively complicated; the optical sensor signal of the fiber electric power sensor sometimes includes voltage and current signals at the same time, so the signal detection and processing methods thereof will also be more complicated. 3.3  Application of optical fiber cable monitoringIn Power Systems The power system has a wide variety of optical cables. In addition, China has a vast area and the environment varies widely. Therefore, the environment of optical cables is also very complex. Temperature and stress are the main environmental factors that affect the performance of optical cables. Therefore, while monitoring the breakpoint of the optical fiber, the temperature and stress conditions of the optical cable are also monitored. It can be seen that the optical fiber cable has far-reaching fault warning and maintenance.  By measuring the frequency shift and intensity of the Brillouin scattered light along the length of the optical fiber, the temperature and strain information of the optical fiber can be obtained, and the sensing distance is relatively long, so it has far-reaching engineering research value. Based on Brillouin Optical Time Domain Reflectance (BOTDR) distributed optical fiber sensing system, using coherent detection technology, the system principle shown in Figure 2.  Figure 2 based on BOTDR sensing system principleThe BOTDR fiber sensing system measures the self-distribution of scattering signals of an optical fiber and its signal strength is very weak, but the coherent detection technology can be used to improve the signal-noise ratio of the system. This solution can be a single light source, single-ended work, the system is simple and easy to implement, and can simultaneously detect fiber breakpoints, loss, temperature, and strain.  IV. Fiber Optic Sensors in Medical Applications In medical fiber, sensors are mainly light-transmitting. With its small size, insulation, non-radio frequency, and microwave interference, high measurement accuracy and good affinity with living organisms, and other advantages. This article will mainly introduce the application of transmission optical fiber in pressure measurement, blood flow velocity measurement, and pH measurement. In addition, it can also be applied to the measurement of temperature and medical image transmission. 4.1 Pressure measurementCurrent clinically applied pressure sensors are mainly used to measure intravascular blood pressure, intracranial pressure, intracardiac pressure, bladder, and urethral pressure. The pressure sensor used to measure blood pressure is schematically shown in Figure3. The pressure-sensitive part is a water-repellent film on the sidewall of the tip of the probe catheter connected to the membrane by a cantilever micromirror and an optical fiber opposite the reflector for transmitting incident light to the reflector while The reflected light is also transmitted.  When there is pressure on the film, the film is deformed and can drive the cantilever to change the angle of the mirror. The light beam coming from the fiber is shone on the mirror and then reflected at the end of the fiber. Since the direction of the reflected light changes with the angle of the mirror, the intensity of the reflected light received by the optical fiber also varies. This change passes through the optical fiber to the other end of the photodetector into an electrical signal, so that by changing the voltage to know the size of the probe at the pressure.Figure 3 Optical fiber pressure gauge probe 4.2 Blood flow velocity measurement Doppler-type optical fiber speed sensor measurement of subcutaneous tissue flow velocity shown in Figure 4, this device uses the optical fiber end reflection phenomenon, the measurement system is simple in structure.Figure 4 optical fiber pressure gauge probeLaser light with a frequency of f passes through the lens and the fiber is sent to the epidermal tissue. For immobile tissue, such as the vessel wall, the reflected light does not produce a frequency shift; and for the red blood cells in the cortex capillary flow rate, the reflected light to produce a frequency shift, the frequency change △ f. The frequency shift of the reflected light The intensity is proportional to the concentration of erythrocytes and the change in frequency can be proportional to the velocity of erythrocytes. Emitted light collected by the optical fiber, the first on the light detector for mixing, and then into the signal processing instrument, which get the red blood cell velocity and concentration. 4.3 PH measurementA schematic diagram of the pH fiber optic sensor used to determine tissue and blood values is shown in Figure 4. Its working principle is the use of emission light, the intensity of transmitted light with the wavelength distribution of the spectrum to be measured. The sensor inserts two optical fibers into an ion-permeable cellulose capsule containing reagent, which penetrates the reagent when the needle is inserted into the tissue or blood vessel, causing the reagent to absorb light of a certain wavelength. Measured such changes, you can get the blood or tissue pH.Figure 5 Determination of pH fiber spectrometerV. Fiber Optic Sensor Features 1.High sensitivity. 2.The geometry has a wide range of adaptability, can be made into any shape of the fiber optic sensor. 3.You can create sensors sensing a variety of different physical information (sound, magnetic, temperature, rotation, etc.) of the device. 4.Can be used for high voltage, electrical noise, high temperature, corrosion, or other harsh environments. 5.But also with the inherent compatibility of optical telemetry technology. The advantages of fiber-optic sensors are that optical fiber sensors use light as a carrier for sensitive information, and use optical fibers as a medium for transmitting sensitive information. Compared with conventional sensors. They have the characteristics of optical fiber and optical measurement and have a series of unique advantages. Good electrical insulation, anti-electromagnetic interference, non-invasive, high sensitivity, easy to achieve long-distance monitoring of the signal under test, corrosion resistance, explosion-proof, flexible optical path, easy to connect with the computer. Sensors are developed in the direction of sensitivity, precision, adaptability, compactness, and intelligence. They can serve as human eyes and ears where people cannot reach(such as high-temperature areas, are as harmful to humans, or nuclear radiation areas). But it is also beyond the physical boundaries of human beings, outsiders can not feel the sensory information. FAQ 1. How does a fiber optic sensor work?Fiber optic sensors work based on the principle that light from a laser or any superluminescent source is transmitted via an optical fiber, experiences changes in its parameters either in the optical fiber or fiber Bragg gratings and reaches a detector which measures these changes. 2. What are fiber optic sensors used for?Optical fibers can be used as sensors to measure strain, temperature, pressure and other quantities by modifying a fiber so that the quantity to be measured modulates the intensity, phase, polarization, wavelength or transit time of light in the fiber. 3.How are fiber optic sensors classified?Based on the operating principle or modulation and demodulation process, a optical fiber sensor can be classified as intensity, a phase, a frequency, or a polarization sensor. All these parameters may be subject to change due to external perturbations. ... These sensors are widely used as chemical sensors. 4. What is active and passive optical fiber sensor?Active fibre optic. -In optical fiber communication, because the signal usually decades during long distance transformation, you need to add an amplifier to boost the signal. Passive fibre optic. - Simply receive light data from the environment, it is commonly used for illumination (Fiber optical lighting. 5. What are the characteristics of optical fiber sensors?Optical fiber sensors have unique advantages, such as high sensitivity, immunity to electromagnetic interference, small size, light weight, robustness, flexibility, and the ability to provide multiplexed or distributed sensing. 6. Which is a use of fiber optics?They are widely used in lighting, both in the interior and exterior of vehicles. Because of its ability to conserve space and provide superior lighting, fiber optics is used in more vehicles every day. Also, fiber optic cables can transmit signals between different parts of the vehicle at very fast speed. 7. Why optical fiber is used for communication?Optical fiber is used by telecommunications companies to transmit telephone signals, Internet communication and cable television signals. ... Due to lower attenuation and interference, optical fiber has advantages over copper wire in long-distance, high-bandwidth applications. 8. Is fiber optic WIFI?Like any Internet service, fiber optic Internet download speeds depend on your connection. Not all fiber services are created equal, much like broadband. ... You can download more, faster, with fiber. Fiber Internet is more reliable than copper and less 'patchy' than Wifi. 9. Is fiber optic analog or digital?Digital signals can be transmitted long distances without degradation as the signal is less sensitive to noise. Fiber optic datalinks can be either analog or digital in nature, although most are digital. Both have some common critical parameters and some major differences. 10. How much data can a fiber optic cable transmit?A new fiber-optic system can carry 800 gigabits of data per second, a big step up from top speeds of 100 or 200 gigabits in today's data centers. You May Also Like:GPS and inertial sensors for driverless applicationsA New Technology for Advancing Opticals,Sensors Even Resistant SupercapacitorsSensors are Always In a State of Rapid Progress

Warm hints: The word in this article is about 2800 words and  reading time is about 15 minutes.     Lithium-ion batteries can be said to be the most mature and widely used new energy sources in the world at present, such as portable electronic products like mobile phones and computers, electric vehicles, electric tools, and energy storage projects. Especially the current Chinese government and other countries are investing to support the development of new energy vehicles and power battery industries. Looking ahead, the lithium industry has a long way to go, such as the development of high energy density systems. The problems of further reduction of cost, the resources recovery, and the utilization are in front of us.   This article will mainly explain what is a lithium battery, then introduce the current situation and future development of lithium-ion battery materials.       Catalog I. What is A Lithium Battery? II. How Does the Lithium Battery Work? III. Distinction Between Lithium-ion Battery & Polymer Lithium Battery IV. Types and Characteristics of Material Used in Lithium Batteries V. Application of Lithium Battery VI. Future Development of Lithium Battery FAQ I. What is A Lithium Battery?   "Lithium battery" is a kind of battery that takes lithium metal or lithium alloy as negative electrode material and using a non-aqueous electrolyte solution. In 1912, lithium-metal batteries were first proposed and studied by Gilbert N. Lewis. In the 1970s, M.S. Whittingham proposed and began to study lithium-ion batteries.   Because of the active chemical characteristics of lithium metal, the environmental requirements of the processing, preservation, and use of lithium metal are very high. Therefore, lithium batteries have not been applied for a long time. With the development of science and technology, lithium batteries have become the mainstream now.   Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium-ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable. The fifth generation of rechargeable lithium metal batteries was born in 1996. Its safety, specific capacity, self-discharge rate, and the ratio of performance to price are superior to those of lithium-ion batteries, which are now produced by a few companies in only a few countries due to their own high-tech constraints.   Li-ion batteries are secondary battery system in which two different kinds of lithium intercalated compounds that can be inserted and removed as positive and negative electrodes respectively. When charged, lithium-ions are removed from the lattice of cathode materials. After the electrolyte is inserted into the lattice of the anode material, the negative electrode is rich in lithium, and the positive electrode is poor in lithium.   When discharged, the lithium-ion is removed from the lattice of the anode material, and then inserted into the lattice of the positive electrode material after the electrolyte, so that the positive electrode material is extremely rich in lithium while the negative electrode is poor in lithium. In this way, the difference between the potential of the cathode material and the lithium-ion when inserted and removed from the lithium metal is the working voltage of the battery.   Li-ion battery is a new generation of green high-energy battery with excellent performance and has become one of the key points in the development of high-tech.   Li-ion battery has the following characteristics: high voltage, high capacity, low consumption, no memory effect, no pollution, small volume, small internal resistance, less self-discharge, and more cycle times.   Because of the above characteristics, the lithium-ion battery has been applied to many civil and military fields, such as mobile phones, notebooks computers, cameras, digital cameras, and so on.   II. How Does the Lithium Battery Work?   The charging and discharging process of lithium battery is realized by the removal and embedding of lithium-ion in the positive and negative electrode of the battery. The reaction equation of the lithium-ion battery with iron phosphate liquid as an example is as follows:   Charging: Discharging:   The electrode reaction of Li/PEO-LiClO4/Pan polymer lithium-ion battery is as follows:   Positive electrode reaction: Negative electrode reaction： The working schematic diagram of lithium battery: Schematic-of-the-lithium-ion-battery-working-principle   1. The positive electrode structure:  LiMn2O4( lithium manganate ) + Conductive agent (acetylene black) + adhesive(PVDF) + Collector negative ( aluminium foil )electrode   2. The negative electrode structure:  Graphite+ Conductive agent (acetylene black) + adhesive(PVDF) + Collector negative ( copper foil )electrode   3. Charging process: The battery is charged by the power supply, and the electron e on the positive electrode runs from the external circuit to the negative electrode. Positive lithium-ion Li+ "jumps" from the positive electrode to the electrolyte, "climb" through the winding hole in the diaphragm, then "swim" to the negative electrode and combine with the electron.    The reaction on the positive electrode is: LiMn2O4 ==Li1-xMn2O4+Xli++Xe (electron).  The reaction on the negative electrode is:  6C+XLi+Xe==LixC6   4. Discharging process When the battery discharges, the electron e on the negative electrode runs from the external circuit to the positive electrode. Positive lithium-ion Li+ "jumps" from the negative electrode to the electrolyte, "climb" through the winding hole in the diaphragm, then "swim" to the positive electrode and combine with the electron.    The reaction on the positive electrode is: Li1-xMn2O4+xli++xe (electron) ==LiMn2O4 The reaction on the negative electrode is: LixC6 == 6C+xLi+xe III. Distinction Between Lithium-ion Battery & Polymer Lithium Battery   As the following table: Electrolyte for Polymer Lithium Battery PolymerElectrolytePure solid polymer electrolyteGel polymer electrolytePAn, PPY, PA, PPPPEO, PPOPAN,PMMA,PVdF   As the following diagram: Different electrolytes are the main differences between lithium-ion batteries and polymer lithium batteries. Diagram IV. Types and Characteristics of Material Used in Lithium Batteries (This is a tutorial on the Lithium Battery Explorer provides an overview of Li-ion battery technology and the properties that are relevant to battery researchers.)   1.Lithium manganate (LMO) LMO, as a kind of lithium battery material with a long history, has high safety, especially strong resistance to overcharge, which is a prominent advantage.   Because of the good structural stability of lithium manganate, the amount of cathode material does not have to exceed the negative electrode in the design of the electric core.   In this way, the number of active lithium ions in the whole system is small, and after the negative electrode is filled, there will not be too many lithium ions in the positive electrode. Even if overcharge occurs, there will not be a large number of lithium ions deposited in the negative electrode to form crystallization. Therefore, the overcharge resistance of lithium manganate is the best in common materials.   In addition, its material price is low, and the production process requirements are relatively low. It is a relatively early widely used cathode material.   But it also has obvious defects. The elevated temperature property of spinel lithium manganese oxide is poor. The existence of oxygen defect makes the core prone to capacity decay at the high voltage stage, at the same time, the cycle use at high temperature would cause a similar capacity decay. The reason is that the trivalent manganese ion which causes the disproportionation effect. The main way to prevent high-temperature attenuation is to reduce the trivalent manganese.   Lithium manganese, limited by its high-temperature performance, is generally not used in high-power or high-temperature environments, such as high-speed passenger vehicles, plug-in cars, and so on. But for electric buses, local logistics vehicles, and so on, lithium manganese is completely competent.     2. Lithium iron phosphate (LFP) The advantages of lithium iron phosphate are mainly reflected in its safety and cycle life. The main determinants are the olivine structure of lithium iron phosphate, which, on the one hand, leads to the lower ion diffusion capacity of lithium iron phosphate. On the other hand, it also has good high-temperature stability and good cycle performance.   The disadvantages of lithium iron phosphate are also obvious, such as low energy density, poor consistency, and poor low-temperature performance.     a) The low energy density is determined by the chemical properties of the material itself. A lithium iron phosphate macro-molecule can accommodate only one lithium-ion.   b)The consistency, especially poor batch stability, is related to not only the level of production management but also its own chemical properties. Lithium iron phosphate is one of the more difficult materials for the preparation of cathode materials for lithium-ion batteries.   The difficulty of consistency and uniformity in this chemical reaction raises another problem at the same time: The impurity of iron and iron in the lithium iron phosphate material always exists, which brings hidden trouble to the battery.   Lithium iron phosphate battery, because of its high safety, although The energy density part affects its range of use., but it is still the main power lithium battery variety of electric vehicle in our country at present, especially buses involving the safety of a large number of people, the national police enforce the use of lithium iron phosphate batteries.     3.Ternary lithium The ternary lithium cathode material synthesizes the advantages of LiCoO2、LiNiO2 and LiMnO2 and forms a synergistic effect within the same core. It combines three requirements of stability and activity of material structure and lower cost, which is one of the three main cathode materials with the highest energy density. The low-temperature performance is also obviously better than the lithium iron phosphate battery.    The higher the content of Ni in the three elements, the higher the energy density of the core and the lower the safety of the core will be. In practical application, the proportion relation of three kinds of materials in the electric core has been changing with the passage of time. The pursuit of energy density is higher and higher, so the proportion of Ni is higher and higher.   The most mentioned disadvantage of ternary material is safety. During the process of thermal runaway, the side reaction product contains a lot of gas, which greatly improves the risk of accident and the ability to spread.   Secondly, the cycle life of ternary materials is also a bottleneck, which has not reached the level of lithium iron phosphate. Last but not least, due to the special microstructure of ternary materials, it is not suitable for high-pressure compaction operation, thus the popular way to increase the energy density is not applicable to it.   The market share of ternary materials is gradually expanding, mainly driven by the pursuit of vehicle range. To catch up with or even surpass that of fuel vehicles, electric vehicles must have as much power as possible in a limited space.   This makes energy density particularly important. The improvement of the safety performance of the battery itself and the improvement of system monitoring and handling accident capability will also promote the expansion of the lithium ternary battery market.   V. Application of Lithium Battery   1. Lithium Iron Phosphate is the most suitable cathode material for Power Battery   After introducing the Types and characteristics of Lithium batteries above, now we will discuss about the most suitable cathode material for power supply.    Since 1996, when the Japanese NTT first exposed lithium iron phosphate cathode materials of olivine structure, John.B.Goodenough professor at Texas University also reported the characteristics of reversible intercalation and removal of lithium from LiFePO4 in 1997.   Since then, lithium iron phosphate has gradually become one of the low-cost, multi-element, and environmentally friendly cathode materials. Compared with traditional cathode materials, spinel LiMn2O4 of spinel structure and layered LiCoO2, the LiMPO4 of olivine structure is extremely stable.   The bond with oxygen is very strong, it will not explode because of the short circuit, the capacity is up to 170 mAh / g, the raw material is more extensive and the price is lower. Because of the similar structure of LiFePO4 and FePO4, the crystal structure of LiFePO4 has almost no rearrangement after the release/embedding of lithium-ion.   Therefore, LiFePO4 has better cycling performance, lithium-ion can enter and exit freely and can charge and discharge more than 1,000 times. It is also reported that lithium iron phosphate can be modified more than 10,000 times.   According to the following picture: Performance comparison of Lithium batteries with different cathode Materials.   Performance comparison Lithium iron phosphate is the most ideal cathode material at present. In comparison, the biggest problem of LiCoO is that it is easy to explode at a low temperature of 150C, and its cost is high (cobalt price is about 500,000 yuan/ton, and the price of LiCoO containing 60% cobalt will be over 400,000 yuan/ton). Also, it has a short cycle life.   The safety of lithium manganese oxide is much better than that of lithium cobaltate, but the cycle life in a high-temperature environment is even worse than that in a high-temperature environment(500 times).   With the advantages of high discharge power, low cost (about 18.3 million yuan/ton), rapid charging and long cycle life of more than 1000 times, the high stability of high temperature and high heat environment, and the good safety performance, lithium iron phosphate is the most ideal lithium cathode material for power vehicles.   At present, though the lithium iron phosphate battery is developing rapidly in China, there are several problems, including patent hidden trouble, low conductivity, and low capacitance, poor low-temperature performance, and low yield. VI. Future Development of Lithium Battery   Polymer Lithium Battery: one of the Future Development directions In addition to pure solid or gel polymer electrolytes, the principle and charge-discharge process of polymer lithium-ion batteries are consistent with those of liquid lithium-ion batteries.   Polymer lithium battery features include plastic flexible, more stable, safer, and less flammable, longer cycle life, higher energy density, high volume utilization(10-20% higher than lithium-ion batteries), no need to use traditional diaphragm materials, and easier for large scale production.   Polymer electrolyte is a kind of functional polymer material with ionic conductivity in solid-state which is formed by complexation of strong polar polymer and metal salt through acid-base reaction. Pure solid-state electrolyte dissolves lithium salts such as LiPF6, LiClO4, and LiBF4 in polymer bulk such as PEO and PPO as solid solvents. Gel electrolytes are electrolytes in a gel state by mixing more liquid solvents with polymer bulk.   Because there is no liquid flowing in the electrolyte, there is no leakage of the battery, so the problems such as burning and explosives are avoided. In order to reduce the thickness of the battery, a polymer lithium battery is usually packaged with aluminum plastic film with a thickness of only 0.1 mm, so it has a higher specific capacity than the ordinary lithium-ion battery.   FAQ   1. What is the difference between a lithium battery and a lithium ion battery? Lithium batteries feature primary cell construction. This means that they are single-use—or non-rechargeable. Ion batteries, on the other hand, feature secondary cell construction. This means that they can be recharged and used over and over again.   2. What are the disadvantages of lithium ion batteries? Despite its overall advantages, lithium-ion has its drawbacks. It is fragile and requires a protection circuit to maintain safe operation. Built into each pack, the protection circuit limits the peak voltage of each cell during charge and prevents the cell voltage from dropping too low on discharge.   3. Why is lithium ion the best battery? Li-ion batteries are able to be recharged hundreds of times and are more stable. They tend to have a higher energy density, voltage capacity and lower self-discharge rate than other rechargeable batteries. This makes for better power efficiency as a single cell has longer charge retention than other battery types.   4. What is the life of lithium ion battery? about two to three years. The typical estimated life of a Lithium-Ion battery is about two to three years or 300 to 500 charge cycles, whichever occurs first. One charge cycle is a period of use from fully charged, to fully discharged, and fully recharged again.   5. Is it good to fully discharge a lithium ion battery? Lithium-ion batteries should not be frequently fully discharged and recharged ("deep-cycled"). You may need to discharge it fully occasionally to recalibrate the capacitiy measuring electronics in the accumulator. Every 30 cycles or so should be enough.   6. How do I know if my lithium ion battery is bad? If the battery is dead or at the end of life, then it won't take charge anymore. If the battery is dead or at the end of life, the battery will swell a bit. The battery starts to heat up very quickly is also one of the indication that your battery is at the end of life.   7. Is there an alternative to lithium-ion batteries? Zinc-ion: A competitive alternative to lithium-ion for stationary energy storage. Lithium-ion batteries are the leading battery technology for both electric vehicles (EVs) and the renewable energy industry.   8. Do lithium ion batteries go bad if not used? Lithium Ion batteries "go bad" when they are stored in discharged state. It is all about battery voltage. If voltage is too low - undesireable chemical reactions will happen and battery will degrade. If battery is not empty and not used for long time - it will be fine.   9. What temperature is bad for lithium batteries? At temperatures above +60°C the Li-ion battery loses capacity constantly and thus performance capability.   10. At what voltage is a lithium ion battery dead? 3.4V. The voltage starts at 4.2 maximum and quickly drops down to about 3.7V for the majority of the battery life. Once you hit 3.4V the battery is dead and at 3.0V the cutoff circuitry disconnects the battery (more on that later. You may also run across 4.1V/3.6V batteries.     You May Also Like: How to Learn Analog Circuit Design Topological Materials are a Promising Material For Boosting Thermoelectric Generation Efficiency Use Polymer Films Material to Make Solar Cell Learn Some Basic Knowledge about Capacitor Voltage Transformer The First Full-Size IBC Bifacial Solar Module in the World