The Kynix Blog - Power

Warm hints: The word in this article is about 2500 and  reading time is about 12 minutes. Summary In the power system, in addition to the traditional harmonic sources, such as electric arc furnace and frequency converter, the nonlinear loads such as new energy access and charging pile may produce a lot of harmonics. In order to prevent harmonic from further affecting the power grid, accurate monitoring and timely treatment of harmonic level in power grid is a necessary step. The correct measurement of harmonic content in power grid is the basis of monitoring and governance. This paper mainly introduces some basic  knowledge about capacitor voltage transformer including the capacitor voltage transformer symbol; testing; working principle; capacitive voltage transformer VS inductive voltage transformer and etc. Article core capacitor voltage transformer Abbreviation CVT English name capacitor voltage transformer Category Power Subject Power engineer compose Capacitive voltage divider and medium voltage transformer Field Energy         Catalogs I. What is Capacitor Voltage Transformer( CVT)3.1 Insulation Resistance Measurement1.1 The Composition of CVT3.2 Capacitance Measurement1.2 CTV Judgment of Common Anomalies3.3 Pressure Swing Ratio Test1.3 CVT Equivalent Circuit Model3.4 Polar MeasurementII.Terminal Sign of Capacitive Voltage TransformerIV.Working Principle of Capacitive Voltage Transformer （CVT)III.Capacitor Voltage Transformer TestingV.Capacitive Voltage Transformer VS Inductive Voltage TransformerⅥ. FAQ  Introduction I. What is Capacitor Voltage Transformer( CVT) 1.1 The composition of CVT 一、The capacitive voltage transformer is mainly composed of a capacitor voltage divider and a medium voltage transformer. The capacitor divider is made up of porcelain bushing and series capacitors installed in it. The porcelain bushing is filled with insulating oil that keeps 0.1MPa positive pressure, and steel bellows are used to balance different environments to maintain oil pressure. The capacitor divider can be used as a coupling capacitor to connect the carrier device. The medium voltage transformer is composed of a transformer, a compensating reactor, a lightning arrester and a damping device installed in a sealed tank, and the space on the top of the tank is filled with nitrogen. The primary windings are divided into main windings and fine tuning windings, and a low loss reactor is connected in series between one side and one winding. Due to the capacitance and the inherent nonlinear impedance of the capacitor voltage transformer sometimes cause Ferroresonance in capacitor voltage transformer, thus suppressing resonant damping device, damping device is composed of a resistor and reactor, connected across the two windings, normally the damping device has very high impedance, when iron magnetic resonance caused by overvoltage in medium voltage transformer affected before the reactor is saturated only resistive load, the oscillation energy will soon be reduced. 1.2 CTV Judgment of common anomalies (1)The secondary voltage fluctuation. The two connection is loose, the distributor is not grounded or the carrier coil is not connected. If the damper is a fast saturable reactor, it may be improper parameter matching. (2)The Secondary voltage is low. Its connection is bad and the electromagnetic unit failure or the capacitor unit C2 is damaged. (3)The secondary voltage is high.The capacitance unit C1 is damaged and the ground end of the partial voltage capacitor is ungrounded. (4)The oil level of the electromagnetic unit is too high. The next capacitance unit is leaking oil or electromagnetic unit into the water. (5)There is a different sound in the transportation. Bolt loosening of reactor or medium pressure rheostat in electromagnetic unit. 1.3 CVT equivalent circuit model Under the condition of steady state, the whole CVT equivalent circuit can be regarded as a linear system, which compensates the stray capacitance of reactor C. The influence of the primary stray capacitance C: of the intermediate transformer at the high frequency can not be ignored. CVT intermediate transformer core can be regarded as linear segments in the magnetization curve, ignoring the core magnetizing inductance, one or two intermediate transformer side leakage resistance reduction to compensation reactor.   II.Terminal sign of capacitive voltage transformer · A single phase transformer with a two - time winding   It represents a single-phase transformer with two times winding. A represents the primary winding terminal of capacitive voltage transformer, and N represents the primary winding grounding terminal of voltage transformer. A represents the two winding terminal terminal of a capacitive voltage transformer, and N represents the first winding grounding terminal of the voltage transformer. · Single phase transformer with two two times windings   It represents a single-phase transformer with two two times windings, A represents the primary winding terminals of capacitive voltage transformers, and N represents the primary winding grounding terminals of voltage transformers. 1A and 2A represent the two winding terminals of the capacitive voltage transformer, and 1n and 2n represent the primary winding grounding terminals of the voltage transformer. · A single phase transformer with two two windings with a tap A single phase transformer with two taps and two winding is represented. A represents the primary winding terminal of capacitive voltage transformer, and N represents the primary winding grounding terminal of voltage transformer. 1A1, 1A2, 2a and 2A2 respectively represent the two winding terminals of the capacitive voltage transformer, and 1n and 2n represent the primary winding grounding terminals of the voltage transformer. · A single phase transformer with a residual voltage winding and two two times windings   It represents a single-phase transformer with a residual voltage winding and two two winding. The A represents the primary winding terminal of capacitive voltage transformer, and N represents the primary winding grounding terminal of voltage transformer. 1A1, 1A2, 2a and 2A2 respectively represent the two winding terminals of the capacitive voltage transformer, and 1n and 2n represent the primary winding grounding terminals of the voltage transformer. Da and DN represent the residual voltage terminal.   Detail III. Capacitor Voltage Transformer Testing 3.1 Insulation resistance measurement The insulation resistance should be measured by the main capacitor, the partial voltage capacitor and the one or two winding insulation resistance of the intermediate transformer. 3.2 Capacitance Measurement The purpose of the test is to determine whether the capacitance of the voltage divider has a change, and the capacitor is insulated without water and dampness.   3.3 Pressure swing ratio test The test transformer exerts high voltage as far as possible. Due to the rise effect in the test, the high voltage voltage must be measured at the high voltage end. The voltage transformer used must be level 0.1 or above to ensure the accuracy of the test results. After the voltage is applied at the high voltage side, the voltage of the low voltage side is measured in turn on the two side and in the auxiliary side, and the voltage ratio is compared with the pressure ratio of the nameplate. 3.4 Polar measurement The purpose of polar measurement is to check the mark of the nameplate. Test method: using DC method, CAR instantaneous addition of 1.5V battery power "+", "-" with "N", respectively, with a multimeter or mA DC or mV meter, pay attention to the polarity put right, A1, A0 "+" X1, XD "-" pointer in the power supply to the deflection of the "+" direction; open to "-" deflection. The test of polarity and pressure variable ratio of windings is usually done in hand over and after overhaul.   IV. Working Principle of Capacitive Voltage Transformer （CVT) There is a video about CVT:   This vidoe explained How Capacitor Voltage Transformer CVT works.Capacitor potential transformer concept is explained.What is high voltage measurement using capacitor type voltage transformer is explained. How to measure high voltage? Educational tutorial on electrical engineering 126 by G K Agrawal. The basic part of the capacitive voltage transformer is the capacitor voltage divider, and it also includes the electromagnetic parts such as the intermediate transformer, the compensating reactor, the damper and so on. Its principle connection is shown in the following picture,the picture shows capacitor voltage transformer wiring diagram capacitance divider is composed of main capacitor C1 and voltage divider capacitor C2 series. Without considering the electromagnetic part, the voltage is divided by capacitance. The voltage on C2 is the following formula: K is the partial voltage ratio. When the two ends of the C2 are connected to the two load, due to C1, C2 The basic part of the capacitive voltage transformer is the capacitor voltage divider, and it also includes the electromagnetic parts such as the intermediate transformer, the compensating reactor, the damper and so on. Its principle connection is given below.   The capacitor voltage divider is composed of the main capacitor C1 and the partial voltage capacitor C2 in series, without considering the electromagnetic part, then the voltage is divided according to the capacitance inverse ratio, and the voltage on the C2 is:   In this formula,K is the ratio of partial pressure When the two ends of C2 are connected to two loads, the larger capacitance internal impedance is due to the existence of C1 and C2, which makes UC2 smaller than the capacitance partial voltage. The larger the load current is, the greater the error is. In order to reduce the capacitance internal impedance, a compensatory reactor L can be connected in series, and the UC2 is not related to the load as much as possible. In fact, because the capacitor has loss, the reactor also has resistance, so that the internal impedance can not be zero, so when the load changes, there will always be error. In order to further reduce the effect of load current, the measuring instrument is connected to the divider after the intermediate transformer TV is boosted. When the two side transformer short circuit occurs, the resistance in the circuit and the total reactance reactor L after compensation are very small, several times the short-circuit current may reach the rated current, will produce a very high voltage resonance in L and C2, in order to prevent overvoltage caused by the breakdown of insulation in capacitor C2 parallel at both ends of the discharge gap F1. Capacitor voltage transformer with capacitance and nonlinear inductance (e.g. TV magnetizing inductance etc.), when the transformer side suddenly close or receive two side and eliminate the impact of sudden short circuit, overvoltage in the transient process may cause nonlinear inductor saturation, which excite ferroresonance overvoltage, such as harmonic 1/3 resonant.  Because the resistance is very small, the resonance will last for a long time, which will cause damage to voltage transformers, instruments and relays, and may lead to incorrect operation of the protective devices. Therefore, the damping resistance RD or damper is often installed on the two side of the capacitive voltage transformer to consume the resonant energy as soon as possible to suppress the ferroresonance. For a common capacitive voltage transformer, a resonant damper is used. It is the capacitance and the inductor in parallel and then added to the damping resistance. In UHV power grid, a capacitive voltage transformer often uses a fast saturation type damper, which is composed of a fast saturation reactance and a damping resistor.     Analysis V. Capacitive Voltage Transformer vs Inductive Voltage Transformer Inductive Voltage Transformers (IVT), are used for voltage metering and protection in high voltage network systems. They transform the high voltage into low voltage adequate to be processed in measuring and protection instruments secondary equipment, such as relays and recorders). A Voltage Transformer (VT) isolates the measuring instruments from the high voltage of the monitored circuit. VTs are commonly used for metering and protection in the electrical power industry. It’s a standard transformer available in the market for step-up or step-down voltages. The advantage is it can be used for high load current and provides isolation.   However,as we mentioned in the above,capacitor voltage transformer is a specialized circuit whose purpose is to convert a high voltage AC signal to lower voltage, usually used with very high input voltages, and a large ratio between input and output voltage. It's usually only used in cases where you're trying to extract a very small amount of power from a high-power circuit, usually for monitoring the high-power circuit. Its advatage is economical but there is no galvanic isolation.   Ⅵ. FAQ 1. What is the function of capacitor voltage transformer?A capacitor voltage transformer (CVT), also known as capacitor-coupled voltage transformer (CCVT), is a transformer used in power systems to step down extra high voltage signals and provide a low voltage signal, for metering or operating a protective relay.   2. Why is CVT used?One of the advantages of a CVT is its ability to continuously change its gear ratio. This means that no matter what the engine speed it, it is always performing at its peak efficiency. CVTs often offer better fuel economy as a result, especially when driving in the city. ... This is because the transmission never shifts.   3. What do you understand CVT and CCVT?Capacitor Voltage Transformer (CVT) or Capacitor Coupled Voltage Transformer (CCVT) is a switchgear device used to convert high transmission class voltage into easily measurable values, which are used for metering, protection, and control of high voltage systems.   4. Why are capacitors used in transformers?At too high common mode frequencies, the inevitable capacitive coupling in the transformer will cause some of the common mode signal on the input to show up as signal on the output. The capacitor provides a more serious connection to ground for AC, while the resistor only a weak connection for DC to avoid ground loops.   5. Why is CVT hated?Because CVTs tend to lock an engine into a specific RPM, generally a high and noisy RPM, making the whole experience very hard on the ears. Also, CVTs are generally tuned for fuel economy rather than performance, and most of the magazines out there are wannabe racecar drivers.   6. What is the function of capacitor voltage transformer?A capacitor voltage transformer (CVT), also known as capacitor-coupled voltage transformer (CCVT), is a transformer used in power systems to step down extra high voltage signals and provide a low voltage signal, for metering or operating a protective relay.

Warm hints: The word in this article is about 1000 and the  reading time is about 6 minutes. MIT researchers found a way to triple the efficiency by using "topological" materials with special electronic properties. Although previous research has indicated that topological materials could be used to create efficient thermoelectric systems, little is known about how electrons in such topological materials can move in response to temperature differences to produce a thermoelectric effect. Researchers not only found that they can push the boundaries of this nanostructured material in a way that makes topological materials a good thermoelectric material,more so than conventional semiconductors like silicon,but also this could be a clean-energy way to help us use a heat source to generate electricity, which will lessen our release of carbon dioxide. NewsToday, thermoelectric devices are used for relatively low-power applications, such as powering small sensors along oil pipelines, backing up batteries on space probes, and cooling minifridges. Scientists hope to develop more efficient thermoelectric devices that will harvest heat produced as a byproduct of industrial processes and combustion engines and convert it into electricity. However, thermoelectric devices' power, or the amount of energy they can generate, is currently limited. "We discovered that we can push the limits of this nanostructured material in a way that makes topological materials a better thermoelectric material than traditional semiconductors like silicon," says Te-Huan Liu, a postdoctoral researcher in MIT's Department of Mechanical Engineering. "In the end, this could be a clean-energy way to help us use a heat source to generate electricity, which will lessen our release of carbon dioxide," Liu added. Liu is first author of the PNAS paper, which includes graduate students Jiawei Zhou, Zhiwei Ding, and Qichen Song; Mingda Li, assistant professor in the Department of Nuclear Science and Engineering; former graduate student Bolin Liao, now an assistant professor at the University of California at Santa Barbara; Liang Fu, the Biedenharn Associate Professor of Physics; and Gang Chen, the Soderberg Professor and head of the Department of Mechanical Engineering.A Path Travel Freely When a thermoelectric material is exposed to a temperature gradient — for example, one end is heated while the other is cooled — electrons begin to flow from the hot end to the cold end, resulting in an electric current. The greater the temperature difference, the more electric current and power are made. The amount of energy that can be produced is determined by the electron transport properties of a given material. Scientists have discovered that certain topological materials can be converted into efficient thermoelectric devices using nanostructuring, a technique used by scientists to create a material by patterning its features at the nanometer scale. Scientists believe that the thermoelectric benefit of topological materials stems from decreased thermal conductivity in their nanostructures. However, it is uncertain how this increase in efficiency relates to the material's inherent, topological properties.     Liu and his colleagues investigated the thermoelectric efficiency of tin telluride, a topological material considered to be a strong thermoelectric material, to try to address this issue. Tin telluride electrons also have unusual properties that resemble a class of topological materials known as Dirac materials. The researchers wanted to understand the effect of nanostructuring on the thermoelectric efficiency of tin telluride by simulating electron movement through the material. Scientists often use a calculation known as the "mean free path" to characterize electron transport. This is the average distance an electron with a given energy can freely travel within a material before being dispersed by different objects or defects in that material. Nanostructured materials resemble a patchwork of tiny crystals, each with its own boundary, known as grain boundaries, that separates one crystal from the next. As electrons come into contact with these limits, they scatter in a variety of ways. Electrons with long mean free paths scatter violently, similar to bullets ricocheting off a wall, whereas electrons with shorter mean free paths are much less affected. The researchers discovered that the electron properties of tin telluride have an important effect on their mean free paths in their simulations. They plotted the spectrum of electron energies in tin telluride against the related mean free paths and discovered that the resulting graph looked very different from that of most traditional semiconductors. In particular, for tin telluride and probably other topological materials, the findings indicate that higher-energy electrons have a shorter mean free path, while lower-energy electrons have a longer mean free path. The researchers then investigated how these electron properties influence the thermoelectric efficiency of tin telluride by essentially summing up the thermoelectric contributions from electrons with different energies and mean free paths. It turns out that the ability of a substance to conduct electricity, or produce a flow of electrons, under a temperature gradient is largely determined by the electron energy. They discovered that lower-energy electrons have a negative effect on the production of a voltage difference, and hence electric current. Since low-energy electrons have longer mean free paths, they can be dispersed more intensely by grain boundaries than high-energy electrons.Size DownGoing a step further in their simulations, the team experimented with the size of individual grains of tin telluride to see whether this had some impact on the movement of electrons under a temperature gradient. They discovered that raising the diameter of an average grain to around 10 nanometers, putting its boundaries closer together, increased the contribution of higher-energy electrons. Higher-energy electrons contribute much more to the material's electrical conduction with smaller grain sizes than lower-energy electrons because they have shorter mean free paths and are less likely to scatter against grain boundaries. As a result, a greater voltage difference can be produced. Furthermore, the researchers discovered that shrinking the average grain size of tin telluride to around 10 nanometers yielded three times the amount of electricity that the material would have produced with larger grains. Although the findings are based on simulations, Liu claims that researchers can achieve comparable results by synthesizing tin telluride and other topological materials and changing their grain size using a nanostructuring technique. Other researchers have proposed that shrinking the grain size of a material can improve its thermoelectric efficiency, but Liu claims that they have mostly assumed that the ideal size is much larger than 10 nanometers. "In our simulations, we discovered that we can shrink the grain size of a topological material far more than previously thought, and based on this principle, we can increase its performance," Liu says. Tin telluride is one of the topological materials that have yet to be discovered. If researchers can determine the optimal grain size for each of these materials, topological materials, according to Liu, can soon be a viable, more effective alternative to producing renewable energy. ConclusionLiu believes that topological materials are excellent for thermoelectric materials, and our findings indicate that this is a very promising material for potential applications. The Solid-State Solar Thermal Energy Conversion Center, an Energy Frontier Research Center of the United States Department of Energy, and the Defense Advanced Research Projects Agency contributed to this research (DARPA). Article From Proceedings of the National Academy of SciencesArticle Edited by kynix 

SummaryThere is an article named "Working principle and Development of Solar Cell" in the Kynix Semiconductor Electronic Blog, it detailed shows that the development of new energy sources mainly concentrates on renewable energies such as solar energy,hydrogen energy, wind energy and geothermal energy, among which solar energy resources are abundant and widely distributed, and are the most promising renewable energy sources. In 1839,French scientist E.Becquerel discovered the photovoltaic effect of the liquid,the solar cell has undergone a long development history of more than 160 years. In terms of the overall development, both basic research and technological advancement have played a positive role in promoting them. Now,researchers at Osaka University, in an international collaboration with Max Planck Institute for Polymer Research, have redesigned one of their previously reported polymers to make a new kind of solar cell that needs no extra special treatments. They also managed to keep excellent power conversion efficiency of solar power to electricity, as recently reported in Advanced Energy Materials.  DiscussionIt's truely that energy industry  is not only the basic industry of national economy, but also a technology-intensive industry.Due to the continuous demand of mankind for renewable energy, people are devoted to developing new sources. The energy that the sun shines on the Earth's surface in 40 minutes can be used for one year at a speed of the current global energy consumption. Reasonable utilization of solar energy will be a long-term development strategy for mankind to solve energy problems and it is also one of the most studied research hot spots.Humankind is in the midst of a massive drive to harness solar energy to power our homes, gadgets, and industry. Plastic solar cells, based on blends of conducting organic polymers, are of interest for making lightweight and cheap solar cells. The problem with these kinds of solar cells is that their solar power efficiencies are very closely related to the way the different types of materials mix and crystalize in thin films. This means complex and careful processing is usually needed to make efficient polymer solar cells. According to lead author Yutaka le,Conventional organic solar cells have now achieved good efficiencies but the polymer films in these devices typically require special processing to ensure correct crystallization.(Organic solar cells, as its name implies, are solar cells that form of organic materials. We are not familiar with organic solar cells, which is a reasonable thing. More than 95% of today's solar cells are silicon-based, while less than 5% of the remaining solar cells are made from other inorganic materials.) Instead, we have been focusing on amorphous polymer blends to avoid these issues. Organic solar cells work based on light energy exciting electrons in a polymer. The excited electrons can then transfer to a soccer ball-shaped fullerene and move to the positive side of the solar cell. The space left by an electron is known as a hole. It too must move through the polymer to the other side of the device to complete the circuit. The Osaka researchers knew that one of their polymers could not transport holes so effectively. They redesigned the structure by adding an extra component, which improved its hole conductivity, and in turn enhanced the solar power conversion performance. Coauthor Yoshio Aso says, "Being able to make these cells without having to pay such close attention to the crystal structure of the polymer films could allow us to mass produce these devices by simple printing methods, which should considerably lower costs of the devices and lead to much wider uptake." 

Summary As is listed in the market,there is a little of small,inexpensive switch for latching power to a load unless you buy low-current,momentary action pushbotton switches like PCB-mount‘tactile types'. However, we can get a suitable latching power switch passing by converting a pushbutton's momentary action into a latching function.   New Design Idea Previous Design Ideas have proposed solutions based on discrete components  and IC-based circuits . The circuit outlined below, however, requires just two transistors and a handful of passive components to achieve the same result.   Circuit One The circuit in Figu1(a) is configured to latch power to a low-side (ground-referred) load. It works in 'toggle' mode; that is, the first switch closure applies power to the load, the second removes power, and so on. fig1  Circuit converts momentary action push switch into latching power switch     To understand how the circuit operates, assume that the DC power supply, +VS, has just been applied, capacitor C1 is initially uncharged, and Q1 is off. The P-channel MOSFET, Q2, is held in its off state by R1 and R3, which work in series to pull the gate up to +VS, such that VGS is zero. The circuit is now in its 'unlatched' state, where the load voltage, VL, at the OUT (+) terminal is zero.   If the normally-open push switch is momentarily closed, C1 – being uncharged – pulls Q2's gate to 0V, thus turning on the MOSFET. The load voltage at OUT (+) now rises immediately toward +VS , and Q1 receives base bias via R4 and turns on. Under these conditions, Q1 saturates and pulls Q2's gate low via R3, thus holding the MOSFET on when the switch has opened. The circuit is now in its 'latched' state, where both transistors are on, the load is energized, and C1 charges up to +VS via R2.   When the switch is momentarily closed for a second time, the voltage on C1 (by now approximately equal to +VS) is transferred to Q2's gate. Since Q2's gate-source voltage is now roughly zero, the MOSFET turns off and the load voltage falls to zero. Q1's base-emitter voltage also falls to zero and the transistor turns off. Therefore, when the switch is released, there is nothing to hold Q2 on, and the circuit reverts to its 'unlatched' state, where both transistors are off, the load is de-energized, and C1 discharges via R2. Resistor R5 across the output terminals is an optional component that acts as a pull-down. When the switch is released, C1 discharges via R2 into the load. If the load impedance is very high (i.e., similar in magnitude to R2), or if it contains active devices such as LEDs, the load voltage at the instant Q2 turns off may be large enough to bias Q1 on via R4, thereby preventing the circuit from turning off properly. The presence of R5 pulls the OUT (+) terminal down to 0V when Q2 turns off, thus ensuring that Q1 turns off rapidly, and allowing the circuit to revert to its unlatched state in a proper manner.   Provided the transistors are correctly rated, the circuit will work over a wide voltage range and is well suited to driving loads such as relays, solenoids, LEDs, and so on. However, beware that certain DC fans and motors continue to rotate when their drive power is removed. This rotation can generate an EMF large enough to bias Q1 on, thereby preventing the circuit from switching off. You can eliminate this problem by inserting a blocking diode in series with the output, as shown in Fig1(b). You must also include R5 to ensure Q1 turns off properly.   Ciruit Two The complementary circuit outlined in Fig2 is intended for 'high-side' loads connected to the positive supply rail such as the relay shown in this example. fig2 Complementary circuit intended for high-side loads   Note that Q1 has been replaced with a PNP transistor, and Q2 is now an N-channel MOSFET. The circuit operates in a similar way to the one described above. Here, R5 acts as a pull-up resistor which pulls the OUT (-) terminal up to +VS when Q2 turns off, thus ensuring that Q1 turns off quickly. As in the previous circuit, R5 is optional and only necessary for the types of load mentioned previously.   Note that in both circuits, the time constant produced by C1-R2 provides for debouncing of the push switch contacts. Normally, a value of 0.25s to 0.5s should be adequate. Smaller time constants may lead to erratic behaviour, whereas a larger time constant increases the waiting time between switch closures necessary to ensure that C1 charges and discharges properly. With C1 = 330nF and R2 = 1MΩ as shown, the time constant is nominally 0.33s. This is usually sufficient to debounce the contacts and to allow the load power to be toggled after a couple of seconds or so.   Both circuits are intended to latch and unlatch in response to brief, momentary switch closures. However, they have each been designed to ensure correct operation even if the push switch is held closed for any length of time. Consider the circuit in Fig2 when Q2 is on. When the switch is pressed to unlatch the circuit, the gate is pulled down toward 0V (since C1 is uncharged) and the MOSFET switches off, allowing  the junction of R1-R2 to rise toward +VS via R5 and the load impedance. At the same time, Q1 also switches off, such that Q2's gate is pulled to 0V via the series combination of R3 & R4. If the switch is released immediately, C1 will simply charge up toward +VS via R2. However, if the switch is kept closed, Q2's gate voltage will be defined by the potential divider formed mainly by R2 and R3+R4. If we assume that the OUT (-) terminal is roughly equal to +VS when the circuit is unlatched, Q2's gate-source voltage is given by: VGS = (+VS) × (R3 + R4)/(R2 + R3 + R4) = 0.02(+VS). Even if +VS is as high as 30V, the resulting gate-source voltage of around 0.6V will be too low to switch the MOSFET on again. Consequently, both transistors remain off until the switch contacts open.   The circuit in Fig2 is latched on by momentarily closing the push switch when C1 has charged up to +VS , which causes OUT (-) to drop to 0V as Q2 immediately turns on, rapidly followed by Q1. A momentary switch closure would allow C1 to discharge to zero via R2 after the contacts open. However, if the switch is held closed, Q2's gate voltage will be defined by the potential divider formed by R2 and R3. Since Q1 is saturated, the junction of R3-R4 at Q1's collector will be pulled up to +VS, and the junction of R1-R2 will be pulled down to 0V via Q2. Therefore, with the switch held closed, Q2's gate-source voltage is given by: VGS = (+VS) × R2/(R2 + R3) = 0.99(+VS). Consequently, provided the supply voltage is at least equal to Q2's gate-source threshold voltage, both Q2 and Q1 will remain on until the switch contacts open.   Both circuits provide an inexpensive way of deriving a latching function from a momentary switch and, just like a mechanical latching switch, the quiescent (unlatched) power dissipation is zero.

SummarySeveral days ago, I was facing a challenge in my lab is--what is the perfect way to power breadboard projects?Situation and SolutionActually,I used breadboards to prototype almost all of my designs and I have always had less than ideal setups.Between my bench power supply, which has banana plugs, and the many wall transformer power supplies I have around the house with 2.1 mm plugs, I just do not have any options that are breadboard friendly.Here,just see the following photos,you will know that I end up with solutions in the past,well,it's not the easiest or prettiest of ways to connect to the breadboard.It does not take more than a casual glance at the pictures above to recognize that while functional, these are not ideal solutions. In both cases, the connections are too easy to accidentally dislodge and there is a risk of a short with the second one.  There had to be a better way.Before a design could be had, it needed some requirements.  As I pondered the requirements, I came up with the following technical specifications for this little device. I wanted to be able to optionally use my bench power supply or wall transformer and that each would have a secure connection to the breadboard.  I also wanted the ability to switch it on or off and have the option to power either both rails or just one with the external supply.As I worked through the design, it became a simple but effective solution.( I am excited)At first,I created a project in Eagle CAD around the connectors I needede,and designed the board shape to match up to the standard 830 point breadboards that I use in my lab. There were a handful of other features I wanted to include such as an optional filter cap, an on/off switch, and a power status LED.   As I got designing, I decided to refine a few of the features.  Many of my projects have more than one input voltage.  To facilitate this, I added a jumper block to connect or disconnect the second power rail for projects that need a dual voltage. Electronic partsHere just let me list the material we need in this project firstly: Deltron 571-0100 : Test Sockets SINGLE PCB SOCK BLKDeltron 571-0500 : Test Sockets SINGLE PCB SOCK REDKobiconn 163-7620E-E : DC Power Connectors PCB 2.1MMFCI / Amphenol 67997-472HLF : Headers & Wire Housings 72P HDRHarwin M7581-08 : Headers & Wire Housings JUMPER SOCKET OPEN TOP REDKOA Speer MF1/2DC1501F : Metal Film Resistors – Through Hole 1.5K 1% 100PPM Kingbright WP710A10SGD : Standard LEDs – Through Hole Grn 40mcd 568nm 40 deg DiffusedPanasonic ECA-1HM100I : Aluminum Electrolytic Capacitors – Leaded 10UF 50V ELECT M RADIAL If you would like to build one following me , these parts you can find from: https://www.kynix.com Schematic and ComponentsWith the basic design framework laid out, I started researching the components needed.  I personally tend to use the online Mouser catalog to help me sort through the vast quantities of components available.  I stuck with all through-hole components to make this project easier to assemble at home.  With all the parts identified, I returned to my project in Eagle CAD and found each of the components in my component libraries.  I connected them electrically as shown in the schematic below, and double-checked the design (an often under rated step in the design process). Board LayoutWith the schematic complete, it was time to move on to the board layout. Breadboards use a standard 0.1 inch pin spacing, but when I measured the spacing between the power busses, I noticed that they were slightly different.  After some trial and error, I realized that the actual spacing between the power bus pins was 1.85 inches O.C.  With the header pins placed at this location, the board outline was adjusted to create a proper fit.  After arranging the components, I added a ground pour to the top layer to simplify routing.  The Eagle autorouter made quick work of the rest of trace routing and the resulting board design looks like this:Board Assembly and TestingI ordered a batch of these boards from my favorite purple PCB vendor (OSHPark) online and assembled them.  I couldn’t be happier with the finished product.  The fit is perfect and they snap into the power bus tightly and stay put.  This little device has gone through extensive testing as I have been using these on all of my breadboard projects ever since I got the first one assembled.  They really work wonderfully!     Article edited by: kynix 

SummaryHappy new year! The year of 2017 has become a past tense,whatever you experienced in the last year,let's celebrate the 2018's coming together ! Today I would like to show you a power projects about the high power voltage current  bridge driver using IR2153&IGBT. Project PhotoThis is a high power voltage current half bridge driver. About IGBT and IR2153IGBT based alf bridge board has been designed for multiple applications,like induction heater driver,tesla coil driver,DC-DC converters,SMPS etc. High current and high voltage IGBTs are used to serve high power requirements. IGBT NGTB40N120FL2WG from ON semi and IR2153 from Infineon semiconductor are important parts of the circuit, IR2153 is a gate driver IC including inbuilt oscillator, 40A/1200V IGBT can handle large current.  Gate driver circuit works with 15V DC and load supply 60V DC to 400V DC.  The IR2153D(S) are an improved version of the Popular IR2155 and IR2151 gate driver ICs, and incorporate a high voltage half-bridge gate driver with a front end oscillator similar to the industry standard CMO 555 timer. The IR2153 provides more functionality and is easier to use than previous ICs. A shutdown feature has been designed into the CT pin, so that both gate driver outputs can be disabled using a low voltage control signal. In addition, the gate driver output pulse widths are the same once the rising under voltage lockout threshold on VCC has been reached, resulting in a more stable profile of frequency vs time at startup. Noise immunity has been improved significantly, both by lowering the peak di/dt of the gate drivers, and by increasing the under voltage lockout hysteresis to 1V. Finally, special attention has been played to maximizing the latch immunity of the device, and providing comprehensive ESD protection on all pins.Oscillation frequency adjustable by onboard Trimmer potentiometer, frequency spans approx. 12 KHz to 100 KHz, duty cycle 50%. Note: Please take appropriate precautions as this power supply uses lethal voltages! Features Load Supply 60V to 400V DCGate Driver Supply 15V DCFrequency Span 12 KHz to 100 KHz, Other frequency range possible, alter R5, PR1, C8Duty Cycle Approx. 50%PR1: Trimmer Potentiometer to set the frequencyCN3: Logic Supply 15V DCCN1: Supply DC InputCN2 : L1 Load SchematicTesla Coil ExampleParts List  Connections Note 1: The circuit is provided with few extra components which may be used as per application requirement other components can be omitted as stated in BOM 2: Frequency span is determined by CT Capacitor (C8) and Trimmer Pot value, refer to datasheet for appropriate value for required frequency span. C8 1Kpf, R5=7k5 and PR1=50K provide frequency span 12 kHz to 100 kHz. 3:  Other Mosfet or IGBT can be used as per your current and voltage requirement. 4: This board also can be used as half bridge driver using IR2101/IR2104 and Mosfet, Header CN3 Pin1 HIN, Pin2 LIN, Omit following components R5, PR1, C8 to use IR2101/IR2105 5: IGBTs require large size heat sink.