Series IGBT Research Articles

Series IGBT Chopping Strategy Based on SVPWM for PMSM Drives with Small DC-Link Capacitance

Series IGBT Chopping Strategy Based on SVPWM for PMSM Drives with Small DC-Link Capacitance

Improved self‐balancing voltage five‐level ANPC converter and its control strategy

SummaryFive‐level active neutral‐point‐clamped (5L‐ANPC) converters have great practical potential in the field of medium and high voltage variable frequency speed regulation. However, the dynamic and static voltage imbalance of the series IGBTs may cause permanent damage to the device, which limits its popularization and application. In this paper, an improved self‐balancing voltage 5L‐ANPC topology (ISBV‐5L‐ANPC) is proposed to address such voltage balancing problem as series switches and high voltage leaps, which realizes dynamic and static voltage equalization by connecting the self‐balancing module consisting of an auxiliary capacitor to the bridge arm, so that it clamps the series switches. In this paper, the operation principle of ISBV‐5L‐ANPC is given in detail, and the control strategy of ISBV‐5L‐ANPC is proposed, and the key parameters in the topology are analyzed and designed. Finally, an ISBV‐5L‐ANPC prototype was built, and the effectiveness of the proposed topology and the feasibility of the control strategy are verified through the experimental results.

A Bidirectional MVDC Solid-State Circuit Breaker Based on Mixture Device

The mixture unidirectional solid-state circuit breaker (SSCB) based on transistor-based devices [i.e., IGBT-based line commutation switch (LCS)] and the thyristor-based devices can combine their respective advantages, however, the conduction loss and cost may increase significantly when expanding to a bidirectional topology because the number of IGBTs had to be doubled with the expansion of unidirectional LCS structure to bidirectional LCS structure composed of two groups of IGBTs in reverse series. In this letter, a full-bridge mixture bidirectional SSCB (FB-MSSCB) requiring only one unidirectional LCS is proposed, the required number of IGBTs can be reduced by at least half compared with other mixture bidirectional SSCB topologies in the same voltage and current level applications. As a result, the FB-MSSCB has advantages of more economic design and higher efficiency, the conduction loss can be reduced by at least 23.3% in 10 kV MVdc system, while retaining other advantages of mixture bidirectional SSCB, such as the ability to actively interrupt bidirectional fault currents, without introducing additional thyristors, charging power supply, and charging strategy. The working principles and designing guidelines is presented in detail. The feasibility and effectiveness are verified by experiment results and comparative analysis.

Basic Topology, Modeling and Evaluation of a T-Type Hybrid DC Breaker for HVDC Grid

Hybrid circuit breaker (HCB) has shown good performance for interrupting dc fault current. However, a massive number of IGBTs in series is needed. These will lead to high costs and significant difficulty in balancing IGBT dynamic voltage. This paper proposes a bidirectional hybrid circuit breaker based on a cascaded half-bridge submodule structure to reduce the overall costs and implementation difficulty of HCB. The number of IGBTs is reduced by 50%, and the operating speed is fast enough. A model of a four-terminal modular multilevel converter (MMC) system with a proposed hybrid circuit breaker in different stages is developed to describe the fault blocking process more clearly. The performance of the proposed HCB is validated and compared with other HCB structure through both theoretical derivation and time-domain simulation.

An Improved DC-Link Series IGBT Chopping Strategy for Brushless DC Motor Drive With Small DC-Link Capacitance

This article proposes an improved DC-link series IGBT chopping strategy for the brushless DC motor (BLDCM) drive equipped with a small DC-link capacitor fed by single-phase AC source. In this strategy, different vector sets are established according to the switching state of the DC-link IGBT and the operation mode of BLDCM. By analyzing the effect of each vector on phase current change rate, a vector selection-based current control scheme is presented. In particular, when the rectifier output voltage is less than the average line voltage of BLDCM, the combined action of vectors with only DC-link IGBT chopping is designed, in order to decrease the converter switching times and reduce the DC-link capacitance at the same time. In addition, the constraint of the DC-link capacitor voltage is analyzed to satisfy the reliable regulation of the motor phase currents, and the calculation method of the DC-link capacitance is given furthermore. The proposed strategy can achieve the smooth operation of the motor with small DC-link capacitance. Meanwhile, the total switching times of the converter are reduced, thereby improving the converter efficiency. The contrastive experimental results verify the correctness of the theories and the effectiveness of the proposed strategy.

一种基于栅极控制的IGBT串联动态均压方法

一种基于栅极控制的IGBT串联动态均压方法

Design, fabrication and testing of 7 kV, 6 A series connected IGBTs switch for triode based 20 kW stage ICRF amplifier

Many high power RF amplifiers, working at various frequencies are being used in ICRH group. High power RF output is obtained by amplification in stages i.e. 50 W, 2 kW, 20 kW, 200 kW. These stages are connected as chain and act as driver for the final stage amplifier of ∼1.5 MW. The high power tubes used in these amplifiers (e.g. Triodes, Tetrodes), need DC power sources up to few mega-watt working at ∼30 kV.The Triodes and Tetrodes that are in use are vulnerable to internal arc faults. To protect them from permanent damage, DC Voltages need to be removed within few tens of microseconds. The conventional power supplies that are being used are short circuited with a very fast switch known as crowbar switch. Ignitron based crowbar switches are widely in use but are being replaced because of the presence of large quantities of toxic Mercury. Further, above crowbar methods cause enormous stress (during the short circuit) of the power supply and can cause considerable disturbance in the power lines.With the development of solid state series switch such short circuits of conventional supplies can be avoided. It is envisaged that a series IGBT switch rated at 7 kV, 6 A would be suitable for HVDC power supply of 20 kW stage.This development involves complete switch design, selection of IGBTs, static and dynamic voltage balancing circuit design. Further, isolation level requirements of various circuits and components are analyzed and adequate isolation is provided. The 7 kV, 6 A series switch is fabricated and successfully tested.

Robust Stability Analysis of Active Voltage Control for High-power IGBT Switching by Kharitonov's Theorem

The main idea of active voltage control (AVC) is to employ classic feedback-control methods forcing the IGBT collector voltage transient to follow a predefined trajectory. This feedback control of IGBTs has great advantages in guaranteeing that IGBTs remain in safe operating area (SOA), restricting EMI, mitigating the voltage/current stress, minimizing/predicting their power losses, and balancing voltages of IGBTs in series. Inevitably, however, AVC introduces stability issues. Based on the assumption that accurate IGBT small-signal model parameters are available, an analogue proportional-derivative and multiloop feedback control was proposed to achieve stable performance in previous work. Due to nonlinearities and uncertainties in IGBT parameters, previous stability analysis methods have important limitations. This work uses Kharitonov's theorem during the IGBT controlled turn-off to assess the system's stability and guide the AVC design to account for model uncertainties and varying parameters. We conducted experiments to investigate the system's robust stability due to these uncertainties in the IGBT parameters, which confirm the validity of the proposed theoretical analysis. With the use of wide bandwidth op-amps, it is shown that the feedback design may be simplified.

Optimisation of the number of IGBT devices in a series–parallel string

High-power semiconductor switches can be realised by connecting existing devices in series and parallel. The number of devices in series depends on the operating voltage of an application and the individual device voltage rating. For a given application, the use of higher voltage rated IGBTs leads to a fewer number of devices and vice versa. The total power loss of the series string equals to the sum of individual IGBT power losses and total loss increases with the increase in operating frequency. The level of increase in power loss depends on the device characteristics. For high current operation, the minimum number of devices depends on the current rating of individual device. In this paper, series IGBT string of six 1.2kV, four 1.7kV, two 3.3kV and a single 6.5kV IGBTs are simulated for a 4.5kV/100A application and power losses are analysed for different frequencies and duty cycles. This power loss analysis is extended for commercial IGBTs to compare the simulation results. The number of devices for minimum power loss depends on operating frequencies and power savings are significant both at low and high frequencies. In addition to the power losses, the other important issues in optimising the number of IGBTs are described in this paper. When IGBT modules are connected in parallel the principle of derating is applied to obtained reliable operation. This is explained with some examples.

공진주파수 추적형 직렬공진 인버터를 이용한 고전압 CCPS에 관한 연구

본 논문은 직렬공진 인버터를 이용한 고전압 커패시터 충전형 전원장치(CCPS)에 관하여 기술하였다. 본 논문에서 사용된 고전압 CCPS는 PLL제어를 사용한 45[Khz]의 직렬공진 인버터를 사용하여 고효율제어를 하였으며, 고전압 변압기를 사용하였다. CCPS의 성능을 평가하기 위하여 14[nF]의 부하에 100[kV]의 출력전압을 300[Hz]의 방전주기를 가지고 실험하였다. 실험결과 최대출력은 18.75[kJ/sec]이고, 방전시간은 200[Hz]로 운전하였으며, 충전시간은 4.5[mS]임을 확인하였다.

STATCOM Applying Flat-Packaged IGBTs Connected in Series

A STATCOM, which compensates 60MVA of a negative-phase-sequence power of Japanese bullet trains, has to achieve a low cost, a small size, and a high reliability. In order to enlarge capacity, the authors have developed techniques of connecting flat-packaged IGBTs in series. This STATCOM consists of two banks of inverters, where 12 single-phase inverters are connected by multistage (four-stage) transformers. When IGBTs are connected in series, the problem is to achieve stable and dynamic voltage balance among IGBTs. In order to realize a practical way, RC snubbers, a gate timing adjustment, and pole clamps are used for dynamic balance and resistors are used for static balance. In addition, active clamping circuits are used to prevent IGBTs from over-voltage during the severe network accident (e.g., short circuit). Furthermore, the control diagram of this STATCOM is shown and a method to operate without resonance between STATCOM and outer filter is discussed. Finally, this STATCOM has been evaluated in the actual field. During experiments of using bullet trains, it was shown that the negative-phase-sequence current was well compensated . The STATCOM has been used in Central Japan Railway Company since September 2003.

The design of an ECRH system for JET-EP

An electron cyclotron resonance heating (ECRH) system has been designed for JET in the framework of the JET enhanced performance project (JET-EP) under the European fusion development agreement. Due to financial constraints it has been decided not to implement this project. Nevertheless, the design work conducted from April 2000 to January 2002 shows a number of features that can be relevant in preparation of future ECRH systems, e.g. for ITER. The ECRH system was foreseen to comprise six gyrotrons, 1 MW each, in order to deliver 5 MW into the plasma (Verhoeven A.G.A. et al 2001 The ECRH system for JET 26th Int. Conf. on Infrared and Millimeter Waves (Toulouse, 10–14 September 2001) p 83; Verhoeven A.G.A. et al 2003 The 113 GHz ECRH system for JET Proc. 12th Joint Workshop on ECE and ECRH (13–16 May 2002) ed G. Giruzzi (Aix-en-Provence: World Scientific) pp 511–16). The main aim was to enable the control of neo-classical tearing modes. The paper will concentrate on: the power-supply and modulation system, including series IGBT switches, to enable independent control of each gyrotron and an all-solid-state body power supply to stabilize the gyrotron output power and to enable fast modulations up to 10 kHz and a plug-in launcher that is steerable in both toroidal and poloidal angles and able to handle eight separate mm-wave beams. Four steerable launching mirrors were foreseen to handle two mm-wave beams each. Water cooling of all the mirrors was a particularly ITER-relevant feature.

Active-gate-control for Snubberless IGBTs connected in Series

High voltage IGBT converters require an IGBT series connection. To reduce converter loss and simplify converter configuration, snubber circuits should be omitted. In this paper we introduce our snubberless IGBT series connection technique with active-gate-control.In the active-gate-control IGBT, gate-voltage is set to increase with collector-voltage. Due to increased gate-voltage, IGBT impedance drops and the collector-voltage is limited. The collector-voltages of IGBTs connected in series can be balanced by uniting the collector-voltages of each single IGBTs independently. In the active-gate-control, the gate is charged before the collector-voltage reaches the clamping voltage. So fast control can be performed and surge voltages at the recovery state can be clamped. In the control the clamping voltage increases with tum-off current and it is saturated for further larger currents. By increasing the clamping voltage with tum-off current, the increase of tum-off loss caused by collector voltage clamping is limited. Saturating the clapping voltage for further higher currents prevents overvoltage failure.

Control of the switching transients of IGBT series strings by high-performance drive units

In the field of power electronics, the use of series-connected insulated gate devices, such as insulated gate bipolar transistors or power MOSFETs, is interesting in order to obtain fast and efficient power switches in medium-range power converters. In this kind of application, the control of the voltage sharing across the series strings of devices is an important aspect to be considered. The proposed technique allows obtaining safe commutations of the switches by simple and effective control circuits acting on the gate side of the power devices. In particular, the gate drive units are arranged in order to ensure good performance during the switching transients, while preventing overvoltage peaks on the devices. Both the design criteria and analysis of the control circuit are developed. Several experimental tests are reported in order to demonstrate the validity and correctness of the proposed approach.

Small Loss Series Resonant Inverter

SummaryA main advantage of the series resonant inverter is its simple structure. It needs only a non-controlled rectifier as power source, because its output power can easily be changed through adjusting frequency or shifting phase of the inverter. Through calculation and experiment it is shown that by these methods. the when output power of the inverter in some range decreases, the turn-off loss increases because its turn-off current increases. This character on the one hand restricts the output capacity and frequency of the inverter, on the other hand reduces the efficiency of the equipment. In order to solve this problem. a novel control method (cycle control method), by which the turn-off current of the switch is always limited to a fairly small value, is presented. The results of simulation with Pspice and a 60 kHz 6 kW IGBT series inverter induction heating equipment demonstrate that the switches of the series resonant inverter by this control method have so small switching losses that they can work in high frequency and large capacity range.

Influence of age of in vitro matured oocytes and electrical stimulations on the development of cattle nuclear transfer embryos

High-power semiconductor switches can be realised by connecting existing devices in series and parallel. The number of devices in series depends on the operating voltage of an application and the individual device voltage rating. For a given application, the use of higher voltage rated IGBTs leads to a fewer number of devices and vice versa. The total power loss of the series string equals to the sum of individual IGBT power losses and total loss increases with the increase in operating frequency. The level of increase in power loss depends on the device characteristics. For high current operation, the minimum number of devices depends on the current rating of individual device. In this paper, series IGBT string of six 1.2 kV, four 1.7 kV, two 3.3 kV and a single 6.5 kV IGBTs are simulated for a 4.5 kV/100 A application and power losses are analysed for different frequencies and duty cycles. This power loss analysis is extended for commercial IGBTs to compare the simulation results. The number of devices for minimum power loss depends on operating frequencies and power savings are significant both at low and high frequencies. In addition to the power losses, the other important issues in optimising the number of IGBTs are described in this paper. When IGBT modules are connected in parallel the principle of derating is applied to obtained reliable operation. This is explained with some examples.