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Warm hints: The word in this article is about 3000 words and  reading time is about 10 minutes.SummaryFull bridge push-pull bi-directional DC/DC converters are mostly modeled by state space averaging method with the complex modeling process. Taking the isolated form push-pull bi-directional DC/DC converter as the research object, this article adopted the pulse-width modulation switch model method to obtain the equivalent circuit model of this converter. Based on this model, this article constructed a closedloop control system of the converter under different working modes, carried out the design and verification of voltage control loop and realized the constant voltage charge-discharge control strategy. The experimental and simulation results verify the correctness of the conclusion. CoreFull bridge push-pullPurposeTo obtain the equivalent circuit model of the converterEnglish nameBidirectional DC/DC convertersCategoryElectromechanical deviceFunctionConverting a source of direct current (DC) from one voltage level to anotherFeatureAdopting the pulse-width modulation switch model method CatalogsCatalogs1. Foreword2.2 Modeling of bi-directional DC/DC converter4 Epilogue2. Principle and design2.3 Voltage Closed-loop Control and Simulation 2.1 The working principle of circuit3 Experimental result   Introduction1. ForewordBidirectional DC/DC converters have been widely applied in many fields such as electric vehicles and battery energy storage systems. Bidirectional DC/DC converters have different circuit topologies according to their applications.I have seen some examples of using Buck/Boost converter to realize the bi-directional flow of electric energy. Because there is no transformer in the converter, so the electrical isolation of the high and low voltage side can not be realized, and only a small voltage range has been allowed. In order to solve this problem, it is proposed to use isolation transformer in bidirectional full-bridge DC/DC transform circuit, but the converter uses too many switching devices and therefore causes too many power losses. The isolated full bridge push-pull bi-directional DC/DC converter has been widely used due to the advantages of both types of converters of itself.At present, the state space averaging method is used to deduce the small signal model of bidirectional DC/DC converter, which needs a large amount of mathematical derivations and calculations. In order to simplify the modeling process, the full-bridge push-pull bi-directional DC/DC converter is modeled by using PWM-switch modeling method. The transfer function between output voltage and duty cycle of the converter is obtained in two modes: boost mode and buck mode. In addition , the voltage closed loop control system is constructed based on the derived circuit model, and the voltage loop is designed and corrected by the compensation network , realizing the constant voltage control of the full-bridge push-pull bidirectional DC/DC converter.First step in developing feedback control for a dc-dc converter is modeling. Here, we model the buck converter in terms of average behavior. Detail2. Principle and design2.1 The working principle of circuitFigure 1 shows the topology of the main circuit of full bridge push-pull bi-directional DC/DC converter. ^The power switch tubes S1～S4  are arranged in the form of a full-bridge circuit;^the power switch tubes S5～S6 are arranged in the form of a push-pull circuit;^CHV is a parallel capacitor with HVDC busbar;^CLV is a parallel capacitor with LVDC busbar;^L is a  low-voltage-side energy storage filter inductor;^HV is high-voltage-side DC bus;^LV is a low-voltage-side DC bus.Figure 1 Main circuit of bidirectional DC/DC converterFigure 2 and 3 respectively give the schematic diagrams of the PWM driving waveform of the power switch tube working in boost and buck mode, and the schematic diagram of the voltage waveform of the primary and secondary sides of the transformer. The u12 shown in the diagram is the transformer primary-side voltage and the u34 is the transformer sub-side voltage.Figure 2 Waveforms of the  power switch tube working in boost modeFigure 3 Waveforms of the  power switch tube working in buck mode2.2 Modeling of bidirectional DC/DC converterThe basic idea of PWM-switch modeling method: the nonlinear part will be linearized by taking an average value of the voltage and the current of it in one switching period when it is a stable circuit, and therefore the nonlinear circuit will turn into a linear circuit. The push-pull bidirectional DC/DC converter working in the buck mode can be equivalent to the circuit shown in Fig. 4 (the circuit in the dashed box is meant to indicate the nonlinear circuit), which turns on during [0, DTs] and turns off during [DTs, Ts], where Ts is the switching cycle and D is the duty ratio of the full bridge push-pull bi-directional DC/DC converter turn on. In the mathematical expressions presented in this article, all the uppercase variables represent the steady-state values, and all the lowercase variables represent the instantaneous values.Figure 4 Conducting circuit in buck mode operationIn the equivalent circuit shown in figure 4, the voltage and current are averaged during a PWM switching cycle, among which idc is primary instantaneous current and iL is secondary instantaneous current of transformer; iC is instantaneous current of electric capacity CLV; ucp is the instantaneous voltage between nodes c and p; uap is the instantaneous voltage between nodes a and p; n is the transformation ratio.Assuming that the duty cycle is d=D, now add an AC small signal to its value attachment (where small angle brackets denote AC small signals and the other variables following are the same), the complete instantaneous value expression for duty cycle is as shown in formula 3:Then substituting equation 3 into the original yields equation 1 and 2, so we have:Neglecting the product term of AC small signal, and equation 4 and 5 of  AC small signal can be simplified as equation 6 and 7:The mathematical relations of voltage and current working in steady state (following yields equation 8 and 9) derived from original yields equation 1 and 2, along with equation 6 and 7 can be used to obtain equivalent circuit model of bidirectional DC/DC converter in Buck mode (see the two-port circuit shown in the dashed box of figure 5). The model is linear since the constraint equations describing the two-port circuit are all linear equations. It can be learned from the above modeling process that the linear model of the full bridge push-pull bidirectional DC/DC converter can be easily established by using the switching model modeling method, which has the advantages of less calculation and simple derivation. It can be learned from the above modeling process that the linear model of the full bridge push-pull bidirectional DC/DC converter can be easily established by using the PWM-switch modeling method, which has the advantages of less calculation and simple derivation.The equation 10 gives transfer function between the output voltage and duty cycle of low voltage side bus according to laws of KCL and KVL.Figure 5 gives the equivalent circuit of bidirectional DC/DC in Buck mode obtained from equation 10, among which UHV is the operating voltage of high voltage side bus in steady state, uLV is the instantaneous voltage of low voltage side bus, n is the transformer ratio, R is the load resistance of low-voltage-side DC bus, Uap/D can be regarded as controlled voltage source, and IL/n can be regarded as controlled current source.Figure 5 Small signal equivalent circuit in Buck mode operationThe transfer function between duty cycle and output voltage in Boost mode can be obtained by using the same analysis method as Buck mode, which has shown in equation 11. R1 is the load of high voltage side bus.2.3 Voltage Closed-loop Control and SimulationFigure 6 gives the block diagram of the closed loop control system of small signal circuit model of the full bridge push-pull bidirectional DC/DC converter in two different operating modes. Charge and discharge at constant voltage in two modes can be realized by voltage closed-loop control.What we can see from figure 6:Uref is the given voltage of high-voltage-side and low-voltage-side DC bus; Hv(s) is the transfer function of sampling; Gm(s) is the transfer function of PWM; Gcv(s) is the transfer function of PI of voltage control loop; Gvd(s) is the transfer function of voltage versus duty cycle.Figure 6 Block diagram of voltage closed loop controlTo theoretically verify the correctness of mathematical model establishment and the feasibility of voltage control strategy, we use the PSIM 9.0 software tool for simulation and analysis in this article. Figures 7 and 8 have respectively shown the simulated waveforms in different operating modes. In Buck mode operation, the voltage of low voltage bus can be stabilized at 12V, so the constant voltage charging has been realized; and in Boost mode operation, the voltage of high voltage bus can be stabilized at 400V, so the constant voltage discharge has been realized, which theoretically verifies the correctness of mathematical model establishment and the feasibility of voltage control strategy. u12 and u34 are the voltages of the primary and secondary sides of the transformer respectively, uHV and uLV are voltages of high-voltage side and low-voltage side bus.Figure 7 Simulated voltage waveform in boost mode operationFigure 8 Simulated voltage waveform in buck mode operation Analysis3 Experimental resultIn order to verify the correctness of the small-signal circuit model and the feasibility of voltage feedback control, we built an experimental platform of full-bridge push-pull bi-directional DC/DC converter using TMS320F28035 as the core control chip.Table 1 gives the main circuit parameters of the bidirectional DC/DC converter based on the full bridge push-pull circuit structure.Table 1 Basic circuit parameters of converterFigure 9 gives the output voltage waveform of secondary voltage and low-voltage-side DC bus of transformer in buck mode operation when steady input voltage of high-voltage-side DC bus is 400V (provided by programmable DC power supply) and load resistance of low-voltage-side DC bus is 0.1Ω (provided by programmable DC electronic load). Here the output current of low-voltage-side DC bus iL is stable at about 120A, the output voltage uLV is about 12V, and the output power of low-voltage-side bus Po is about 1.5kW which meets the requirement of rated power designed, now we have realized  the constant-voltage charging of low-voltage-side DC bus.Figure 9 The voltage waveform in Buck mode operationFigure 10 gives the output voltage waveform of primary voltage and  high-voltage-side DC bus of transformer in boost mode operation when steady input voltage of low-voltage-side DC bus is 12V (provided by low-voltage DC power supply) and load resistance of high-voltage-side DC bus is 105Ω (provided by high voltage resistance load box). Here the output current of high-voltage-side DC bus iH is stable at about 3.7A, the output voltage of high-voltage-side DC bus uHV is stable at about 400V, and the output power of high-voltage-side bus Po is about 1.5kW which meets the requirement of rated power designed, until now we have realized  constant-voltage discharge of high-voltage-side DC bus.Due to the high level at the output, technical problems in the winding process for power transformers and the whole experimental device completing by manual welding, the rate of heat dissipation of power transformer appears to be somewhat low and the parasitic inductance and inductive coupling is also rocking the boat, and then we see the voltage waveform oscillation at zero crossing of transformer voltage in Boost mode moderation. However, under the condition of steady state parameters, this experimental platform can work normally and stably for a long time according to the design requirements and can meet the needs of practical applications.Figure 10 The voltage waveform in Boost mode operationFigure 11 is a schematic diagram of the hardware platform which is mainly composed of main circuit board, control circuit board and corresponding test equipment.Figure 11 physical photographs of experimental devices4 EpilogueAccording to the characteristics of bidirectional DC/DC converter applied in fields of battery and electric vehicle energy storage management, a bidirectional DC/DC converter based on full-bridge push-pull topology is obtained by comparing with different circuit topologies. Different from the traditional state-space average modeling, the method of PWM-switch modeling is used now to build small signal equivalent circuits in different mode operations, and the voltage loop has also been designed and corrected. The high-power constant voltage charging is realized in Buck mode moderation and the high-power constant voltage discharge is also realized in boost mode operation. Both modes can work normally and stably to meet the performance requirements of practical applications, which appear to be in high value at fields of battery and electric vehicle energy storage management. Book SuggestionSoft-Switching PWM Full-Bridge Converters: Topologies, Control, and DesignJun 23, 2014This book intends to describe systematically the soft-switching techniques for pulse-width modulation (PWM) full-bridge converters, including the topologies, control and design, and it reveals the relationship among the various topologies and PWM strategies previously proposed by other researchers. The book not only presents theoretical analysis, but also gives many detailed design examples of the converters.---by Xinbo RuanPower Electronics: Converters and RegulatorsOct 28, 2016This book is the result of the extensive experience the authors gained through their year-long occupation at the Faculty of Electrical Engineering at the University of Banja Luka. Starting at the fundamental basics of electrical engineering, the book guides the reader into this field and covers all the relevant types of converters and regulators. Understanding is enhanced by the given examples, exercises and solutions. Thus this book can be used as a textbook for students, for self-study or as a reference book for professionals.---by Branko L. Dokić and Branko BlanušaPulse-Width Modulated DC-DC Power ConvertersOct 26, 2015With improved end-of-chapter summaries of key concepts, review questions, problems and answers, biographies and case studies, this is an essential textbook for graduate and senior undergraduate students in electrical engineering. Its superior readability and clarity of explanations also makes it a key reference for practicing engineers and research scientists. Following the success of Pulse-Width Modulated DC-DC Power Converters this second edition has been thoroughly revised and expanded to cover the latest challenges and advances in the field.---by Marian K. Kazimierczuk Relevant information "Modeling and Control of Full Bridge Push-Pull Bi-Directional DC/DC Converter"About the article "Modeling and Control of Full Bridge Push-Pull Bi-Directional DC/DC Converter", If you have better ideas, don't hesitate to  write your thoughts in the following comment area. You also can find more articles about electronic semiconductor through Google search engine, or refer to the following related articles:How to Learn Analog Circuit DesignLook Forward to the Future of Semiconductor

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.

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. 

SummaryRecently the designers found a approach to improve speed,cost and linearity of A-D conversion--Using  ‘voltage-to-frequency converters’(VFCs) to perform A-D conversions in data acquisition systems that require strict monotonic response,high resolution and reuced noise and moderate speed.The VFC produces a pluse train with frequency proportional to the input voltage.Then a microcontroller or logic converts fre quency into a number by opening a gate for a fixed amount of time and counting how many.However,this approach is not perfect.the main drawback is that to increase speed, designers have to run the VFC at high frequency, which deteriorates linearity.   Design Ideathe design idea of this aproach reverses things.A circuit converts input voltage into a proportional time interval;then,the micro uses that interval to count pulses coming from its internal clock.The results are impressive:1.Good linearity as the voltage-to-period converter runs at low frequency2.Faster A-to-D conversion due to the high value of the clock frequency3.Potentially simpler program or logic, as it only has to count clock pulses, gated by the circuit4.Low priceCircuit and Voltage IssueThe key is that increasing the count frequency does not affect linearity of the A-to-D conversion, while increasing the frequency of the VFC always means worse linearity.Just see the following picture: This picture is a circuit about modified VFC,where the input voltage VIN and the reference voltage VREF swap their roles. The R1-R2 network shifts the input voltage so it is always more positive than the reference voltage and maintain proper operating conditions. The circuit uses all switches of the 4066 part: two in parallel build S1 to reduce the effect of imperfect switch flatness on linearity, one switch goes for S2, and the last switch is part of the start-up circuit, paralleling CINT, and controlled by the logic during initialization.As the input voltage changes from 0 to 5V, the output period changes from 78 to 578µs. Integration capacitor CINT and the threshold level of the one-shot’s Schmitt input do not participate in the period vs voltage relation.Filling the period with 10MHz clock pulses generates numbers from 780 to 5780 – one count per millivolt. Linearity is one count or ±0.02%, which is not a surprise when the maximum frequency is only 12.8kHz. The maximum time of the A-to-D conversion is 578µs. This is 8.65 times faster compared to the case of a 1MHz VFC, where it would take 5,000µs to count 5,000 pulses of 1µs. The interface program is short and simple.Calibration involves some back and forth due to the shift of the input voltage: adjust sensitivity to 100µs/V using the trim-pot of the one-shot. The nominal duration of the one-shot pulse is 26µs. Cancel the 780 count offset in the controller.The following table  shows that the V-to-P approach is significantly better than the V-to-F one (Refs 3, 4). Surprisingly, no chip-maker offers this type of converter.

SummaryRS-485 has been an industrial workhorse because of its robustness and reliability.  Initially used as a communication network in laboratory instrumentation, RS-485 can be found in applications ranging from building automation to traffic monitoring systems. As the use of RS-485 grew, demand increased for a higher output voltage swing, a wider common-mode range and increased tolerance to electrostatic discharges. There was also a need for greater stand-off capability or protection against persistent over-voltages beyond the maximum transceiver supply level specified in datasheets.  OVP Versus Transient Protection  As the above picture shows,the 24V and 48V DC supplies in industrial and telecom systems are commonly distributed through the same conduits as the data lines of an RS-485 network,there can be multiple causes for over-voltage faults when data lines share the same conduits as DC power lines. On the one hand,if a DC supply shares the same connector or screw terminal block with the data lines of an adjacent bus node circuit,wiring faults can occur that connect one or more supply conductors with the transceiver bus terminals. Another cause of failures is the layouto of the conduit. Sharp bends often violate the minimum cable radius specified for data and supply cables. Over time, the increased mechanical pressure on the cable will cause a break in the insulation, causing shorts between power and data lines. This can also happen when machinery or equipment is placed against a conduit, thus crunching the cable. Over-voltage events can last for minutes and even up to weeks until their causes are eliminated. Much shorter over-voltage events, such as over-voltage transients, can occur due to load switching activity in the power distribution system and lightning strikes, which induce high surge currents and voltages into the data lines. Engineers new to over-voltage protection often assume that protection against short- and long-term over-voltages can be provided by adding external transient voltage suppressors (TVS) to a non-fault protected, standard transceiver. This is not true because the maximum power which the TVS can absorb decreases with increasing transient duration. The following image shows a 600W TVS rated at 1ms pulse width. Note that the time axis ranges from 10μs to 10ms, with power levels of 6kW and 200W respectively. From this characteristic, it should be clear that exposing a TVS to long-term over-voltages would fry the device.  Therefore fault protected transceivers are needed to protect bus nodes against a wide range of over-voltages. These transceivers can provide protection against DC over-voltages of up to ±60V and transient over-voltages of up to ±80V.   Integrated Versus DiscreteOccasionally, designers ask ‘why not use a non-fault protected, standard transceiver and a few discrete low-cost transistors with sufficient high voltage breakdown for over-voltage protection?’. The answer is simple: A discrete solution adds more cost and development time and consumes more space than a fault-protected transceiver. Let's assume the function of the fault-protected, half-duplex transceiver in the following picture is to be accomplished with a discrete design using a standard transceiver. First, the transmit path and the receive path must be separate to allow for the implementation of a boosted output stage with high standoff voltage. This requires the use of a full duplex transceiver. The output stage could be realised with four discrete transistors or an integrated H-bridge, whose control inputs require the conversion of RS-485 bus signals into TTL or CMOS logic levels. This would require a drive logic circuit between the transceiver and the discrete output stage. In the receive path, a discrete voltage limiter, consisting of Zener diodes and series resistors, must be implemented to limit the bus voltage during an over-voltage event, otherwise it remains transparent. The following picture shows that the discrete solution already becomes cumbersome by merely providing the basic functions for over-voltage protection, while still lacking a current limiter, which is a vital component for over-voltage protection. Current limiting is a critical function during over-voltage events when the driver is actively driving the bus. Because the enabled driver presents a low-impedance connection to ground, bus currents flowing through the driver become huge, damaging the device if they are not limited. Current LimitingFault-protected transceivers with common-mode ranges wider than specified in the RS-485 standard require double fold-back current limiting within the driver stage. Figure 4 shows the current limiting function of the ISL3245x family of fault-protected transceivers that operate over the wide common-mode range of ±20V. Here, the first fold-back current level of 63mA ensures that the driver never folds back when driving loads within the entire 40V common-mode voltages. The low second fold-back current setting of 13mA minimises power dissipation if the driver is enabled when a fault occurs. This current limiting scheme ensures that the output current never exceeds the RS-485 specification, even at the common mode and fault condition voltage range extremes. In the event of a major short-circuit condition, the transceivers also provide a thermal shutdown function that disables the drivers whenever the die temperature becomes excessive. This eliminates any power dissipation and allows the die to cool. The drivers automatically re-enable after the die temperature drops by 15°C. If the fault condition persists, the thermal shutdown/re-enable cycle repeats until the fault is cleared. Receivers stay operational during thermal shutdown and fault-protection is active, regardless of whether the driver is enabled, disabled or the IC is powered down.The energy of over-voltage transients caused by lightning can easily exceed the transceiver's fault protection and must be absorbed by external TVS diodes. Two conditions need to be satisfied when adding external TVS devices to a fault-protected transceiver: The TVS breakdown voltage must be 1V higher than the highest common-mode voltage of the application or the maximum DC-supply, whichever is higher.The peak clamping voltage of the TVS must be less than the transceiver’s maximum fault-protection levels.Fault-protected transceivers with a wide supply voltage range enable designers to use the same device in 3.3 and 5V systems, which reduces logistics and can lead to an attractive price break for higher volumes. However, not all 3V to 5V transceivers provide sufficient drive capability at low supply and neither do they necessarily operate down to 3V. ClosingSystem designers are no longer required to choose between robust fault tolerance and high performance in RS-485 and RS-422 transceivers; devices such as the ISL32458E and ISL32459E from Intersil offer both. These transceivers feature ±60V over-voltage and ±15kV ESD tolerance, while including operation from supply voltages ranging from 3V to 5.5V. They also operate with data rates of up to 20Mbit/s and provide a ±20V common-mode voltage range. In addition the ISL32459E provides a cable-invert function.  Article resources: Writed by Thomas Kugelstadt,a principal applications engineer with Intersil, a Renesas companyArticle edited by kynix