Snubberless voltage sharing of series-connected insulated-gatedevices by a novel gate control strategy

Insulated gate devices, such as metal oxide semiconductor field effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs), are increasingly used in high-voltage power converters where a request for fast power switches is growing. Series connection of devices is a viable approach to manage voltages higher than the blocking voltage of the single device. The main problem in such an application is to guarantee the voltage balance across the devices both in steady-state and during switching transients. In this paper, a novel approach is presented, which is used to equalize the voltage sharing during the switching transients. The main advantages of the proposed method consist in avoiding the traditional use of the snubber capacitors, in the output power side, and in working on the gate side. The application of the proposed gate drive technique is firstly discussed and compared with different solutions, hence, validated by experimental tests applied to the control of series connected devices. Finally, a comparison is performed between the transient behaviors of two different configurations: a single switch with high-voltage blocking capability, and in alternative a series of two devices which together ensure the voltage blocking capability of the single switch. The better performances of the latter configuration, working with the proposed control circuit, over the former have been experimentally demonstrated     

Recent developments of high power converters for industry andtraction applications

The introduction of new high power devices like integrated gate commutated thyristors (IGCTs) and high voltage insulated gate bipolar transistors (IGBTs) accelerates the broad use of pulse width modulation (PWM) voltage source converters in industrial and traction applications. This paper summarizes the state-of-the-art of power semiconductors. The characteristics of IGCTs and high voltage IGBTs are described in detail. Both the design and loss simulations of a two level 1.14 MVA voltage source inverter and a 6 MVA three-level neutral point clamped voltage source converter with active front end enable a detailed comparison of both power semiconductors for high power PWM converters. The design and the characteristics of a commercially available IGCT neutral point clamped PWM voltage source converter for medium voltage drives are discussed. Recent developments and trends of traction converters at DC mains and AC mains are summarized     

A novel single-phase ZCS-PWM high-power-factor boost rectifier

This paper presents a novel single-phase high-power-factor (HPF) pulsewidth-modulated (PWM) boost rectifier featuring soft commutation of the active switches at zero current (ZC). It incorporates the most desirable properties of conventional PWM and soft-switching resonant techniques. The input current shaping is achieved with average current mode control and continuous inductor current mode. This new PWM power converter provides ZC turn on and turn off of the active switches, and it is suitable for high-power applications employing insulated gate bipolar transistors (IGBTs). The principle of operation, the theoretical analysis, a design example and experimental results from a laboratory prototype rated at 1600 W with 400 VDC output voltage are presented. The measured efficiency and the power factor were 96.2% and 0.99%, respectively, with an input current total harmonic distortion (THD) equal to 3.94%, for an input voltage with THD equal to 3.8%, at rated load     

An improved ZCS-PWM commutation cell for IGBT's application

An improved zero-current-switching pulsewidth-modulation (ZCS-PWM) commutation cell is proposed, which is suitable for high-power applications using insulated gate bipolar transistors (IGBTs) as the power switches. It provides ZCS operation for active switches with low-current stress without voltage stress and PWM operating at constant frequency. The main advantage of this cell is a substantial reduction of the resonant current peak through the main switch during the commutation process. Therefore, the RMS current through it is very close to that observed in the hard-switching PWM converters. Also, small ratings auxiliary components can be used. To demonstrate the feasibility of the proposed ZCS-PWM commutation cell, it was applied to a boost converter. Operating principles, theoretical analysis, design guidelines and a design example are described and verified by experimental results obtained from a prototype operating at 40 kHz, with an input voltage rated at 155 V and 1 kW output power. The measured efficiency of the improved ZCS-PWM boost converter is presented and compared with that of hard-switching boost converter and with some ZCS-PWM boost converters presented in the literature. Finally, this paper presents the application of the proposed soft-switching technique in DC-DC nonisolated power converters     

Active gate voltage control of turn-on di/dt and turn-off dv/dt in insulated gate transistors

As the characteristics of insulated gate transistors [like metal-oxide-semiconductor field-effect transistors and insulated gate bipolar transistors (IGBTs)] have been constantly improving, their utilization in power converters operating at higher and higher frequencies has become more common. However, this, in turn, leads to fast current and voltage transitions that generate large amounts of electromagnetic interferences over wide frequency ranges. In this paper, a new active gate voltage control (AGVC) method is presented. It allows us to control the values of di/dt at turn-on and dv/dt at turn-off for insulated gate power transistors, by acting directly on the input gate voltage shape. In an elementary switching cell, it enables us to strongly reduce over-current generated by the reverse recovery of the free-wheeling diode at turn-on, and oscillations of the output voltage across the transistor at turn-off. In the following sections, the AGVC in open and closed-loop for IGBT is presented, and its performance is compared with that of a more conventional method, i.e., increasing the gate resistance. Robustness of the AGVC is estimated under variations of dc-voltage supply and transistor switched current.     

The series connection of IGBTs with active voltage sharing

This paper presents the reasons that make series operation of insulated gate bipolar transistors (IGBTs) attractive and challenging and reviews the methods that may be used. Then, a new approach, which uses the IGBT's gate-controlled active regime in place of large voltage-sharing snubbers, is proposed. Analytical and simulation techniques are used to study the performance and conditions for stability given. It is concluded that when making each IGBT voltage follow a reference input, with closed-loop voltage control, the IGBTs are able to share the transient turn-off voltage without turn-off snubbers. This technique may lead to more compact and efficient high-voltage-power modules     

Active Voltage control of IGBTs for high power applications

The operation of an insulated gate bipolar transistor (IGBT) in its active region is a well established technique for withstanding short circuits and also for dv/dt control. In this paper, we exploit the active behavior of the IGBT, applying a voltage feedback loop to the IGBT to control its switching. It is shown that adding a bias to the demand reference waveform shifts the IGBT into the active region and permits wide bandwidth operation over most of the switching transient. The operation of the IGBT is reported in detail, making reference to a selection of experimental waveforms for 400-A, 1700-V capsule IGBTs. The implementation required for control of such large IGBT modules and capsule devices for high power applications is described and discussed. It is concluded that the active voltage control method allows the operation of high power IGBT circuits to be closely defined.     

Modelling of the shoot-through phenomenon introduced by the next generation IGBT in inverter applications

The shoot-through phenomenon has not been fully discussed for high-power inverters with IGBTs. This is because a negative gate voltage is applied to IGBTs during off states. Recently, attention is paid to an improved gate driver with only a positive gate voltage in order to meet demands for simplification, integration, and reduction in power consumption as well as in cost of the gate driver. Moreover, the threshold voltage of the next-generation IGBT will decrease with microfabrication techniques of the gate structure. This will make the shoot-through phenomenon severer and degrade the inverter reliability with the next-generation IGBTs. The influence of the parasitic parameters in both the IGBT and circuit on the shoot-through mechanism has not been investigated so far.This paper clarifies the shoot-through mechanism and investigates the impact of the next generation IGBTs on the inverter reliability. The influence of the internal capacitance of IGBT including stray inductance on inverter reliability is experimentally confirmed.     

The future of power semiconductor device technology

Power electronic systems have benefited greatly during the past ten years from the revolutionary advances that have occurred in power discrete devices. The introduction of power metal-oxide-semiconductor field-effect transistors (MOSFETs) in the 1970s and the insulated gate bipolar transistors (IGBTs) in the 1980s enabled design of very compact high-efficiency systems due to the greatly enhanced power gain resulting from the high input impedance of these structures. Recently, significant improvements in the performance of silicon-power MOSFETs has been achieved by using innovative vertical structures with charge coupled regions. Meanwhile, silicon IGBTs continue to dominate the medium- and high-voltage application space sue to scaling of their voltage ratings and refinements to their gate structure achieved by using very large scale integration (VLSI) technology and trench gate regions. Research on a variety of MOS-gated thyristors has also been conducted, resulting in some promising improvements in the tradeoff between on-state power loss, switching power loss, and the safe-operating-area. Concurrent improvements in power rectifiers have been achieved at low-voltage ratings using Schottky rectifier structures containing trenches and at high-voltage ratings using structures that combine junction and Schottky barrier contacts. On the longer term, silicon carbide Schottky rectifiers and power MOSFETs offer at least another tenfold improvement in performance. Although the projected performance enhancements have been experimentally demonstrated, the defect density and cost of the starting material are determining the pace of commercialization of this technology at present     

Active gate control of series connected IGBTs using positive current feedback technique

Controllable devices like insulated gate bipolar transistors (IGBTs) are very popular on account of their highly desirable features. This prompts their use in high-voltage applications. But high-voltage IGBT development is facing constraints and there is a requirement for series connection of these devices to enhance their voltage withstanding capability. The series connection of IGBTs, however, has its own problems (e.g., dynamic voltage imbalances leading to device break down etc.). Active gate control offers a good solution to this problem. In this brief, a novel scheme of "active gate control using a positive current feedback" is proposed. The system uses a current feed back network where the gate voltage is dependent on the current through the device but not on the overvoltage across the device (the existing trend). The scheme has been simulated using PSPICE and validated experimentally. Analytical and control aspects are discussed. All the results are included. It is concluded that the proposed technique leads to a simple modular control circuit, wider range of operating currents, and increased system stability.     

A 6.6-kV Transformerless Motor Drive Using a Five-Level Diode-Clamped PWM Inverter for Energy Savings of Pumps and Blowers

This paper describes a 6.6-kV adjustable-speed motor drive for pumps and blowers without transformer. The power conversion system consists of a front-end diode rectifier, a five-level diode-clamped pulsewidth modulation (PWM) inverter with a voltage balancing circuit, and a hybrid active filter for harmonic-current mitigation of the diode rectifier. The control of the inverter is characterized by superimposing a third-harmonic zero-sequence voltage on each of the three-phase reference voltages to achieve the so-called overmodulation and reduce the switching stress of insulated gate bipolar transistors (IGBTs). A 200-V 5.5-kW downscale model is designed, constructed, and tested with focus on the five-level PWM inverter and the voltage balancing circuit. Experimental results obtained from the 200-V downscale model verify the viability and effectiveness of the 6.6-kV adjustable-speed motor drive, showing that the four split dc capacitor voltages are well balanced in all the operating conditions and that the switching stress of the IGBTs is reduced at low modulation indexes.     

Numerical Optimization of an Active Voltage Controller for High-Power IGBT Converters

Feedback control of insulated gate bipolar transistors (IGBTs) in the active region can be used to regulate the device switching trajectory. This facilitates series connection of devices without the use of external snubber networks. Control must be achieved across the full active region of the IGBT and must balance a number of conflicting system goals including diode recovery. To date, the choice of control parameters has been a largely empirical process. This paper uses accurate device models and formalized optimization procedures to evaluate IGBT active voltage controllers. A detailed optimization for the control of IGBT turn-on is presented in this paper     

Development of a low cost fuel cell inverter system with DSP control

In this paper, the development of a low cost fuel cell inverter system is detailed. The approach consists of a three-terminal push-pull dc-dc converter to boost the fuel cell voltage (48V) to /spl plusmn/200 VDC. A four switch [insulated gate bipolar transistor (IGBT)] inverter is employed to produce 120-V/240-V, 60-Hz ac outputs. High performance, easy manufacturability, lower component count, safety and cost are addressed. Protection and diagnostic features form an important part of the design. Another highlight of the proposed design is the control strategy, which allows the inverter to adapt to the requirements of the load as well as the power source (fuel cell). A unique aspect of the design is the use of the TMS320LF2407 DSP to control the inverter. Two sets of lead-acid batteries are provided on the high voltage dc bus to supply sudden load demands. Efficient and smooth control of the power drawn from the fuel cell and the high voltage battery is achieved by controlling the front end dc-dc converter in current mode. The paper details extensive experimental results of the proposed design on Department of Energy (DoE) National Energy Technology Laboratory (NETL) fuel cell.     

Zero-Voltage and Zero-Current Switching Full-Bridge DC–DC Converter With Auxiliary Transformer

A novel zero-voltage and zero-current switching (ZVZCS) full-bridge phase-shifted pulsewidth modulation (PWM) converter using insulated gate bipolar transistors (IGBTs) with auxiliary transformer is proposed to improve the properties of the previously presented converters. ZVZCS for all power switches is achieved for full load range from no-load to short circuit by adding active energy recovery snubber and auxiliary circuits. The principle of operation is explained and analyzed and experimental results are presented. The features and design considerations of the converter are verified on a 3-kW, 50-kHz IGBT based experimental circuit.     

Actively clamped zero-current-switching quasi-resonant convertersusing IGBTs

Conventional zero-current-switching quasi-resonant power converters (ZCS-QRCs) suffer from the disadvantages of high switch current stress and variable switching frequency. This paper proposes the use of a “current-clamping circuit” to overcome these disadvantages. By incorporating such a circuit into the family of ZCS-QRCs, a new family of actively clamped ZCS-QRCs using insulated gate bipolar transistors (IGBTs) is derived. These power converters feature high (and constant) switching frequency and zero-current turn-off (without increased current stress), which are particularly useful for high-power applications where minority-carrier semiconductor devices (such as IGBTs and bipolar junction transistors) are used as power switches. The design criteria, simulation and experimental results are reported     

Monolithically integrated high-power broad-band RF switch based on III-N insulated gate transistors

We report on the high-performance monolithically integrated RF switch based on metal-oxide-semiconductor III-N heterostructure field-effect transistors (MOSHFETs). The radio frequency (RF) switch microwave monolithic integrated circuit (MMIC) consists of three submicron-gate MOSHFETs connected into /spl pi/-type configuration. In the 0-10 GHz frequency range, the insertion loss is less than 1dB and the isolation is better than 20 dB. The switching powers well exceed 20 W per 1mm of the active element width. The high performance parameters of the switch are achieved due to unique properties of III-nitride MOSHFET, which combines a low channel resistance and high breakdown voltage features of AlGaN/GaN HFETs and extremely low gate leakage currents, large gate voltage swing and low gate capacitance specific to insulated gate design. The combination of these parameters makes MOSHFETs excellent candidates for high-power switching. The experimental data obtained from the RF switch are in close agreement with the results of simulations.     

基于微波整流的半导体开关无线控制

针对有源电子标签及传感器节点低功耗唤醒模块的需求,设计了一种基于微波整流的半导体开关无线控制方法。通过微波整流之后的直流输出电压来控制半导体开关的状态,进而控制唤醒电路的直流电源通断,利用半导体开关关断状态下漏电流极低的特点,确保设备在休眠期达到极低功耗,从而延长标签及节点电源的工作时间。文中的微波整流设计主要以实现最大化直流输出电压为目标,整流天线部分采用双单元的整流阵列设计。仿真与测试结果表明,每一路天线接收到-18 dBm的射频功率时,直流输出电压可达到典型的CMOS开关控制所需的最低电平(1 V)。     

Structure oriented compact model for advanced trench IGBTs without fitting parameters for extreme condition: Part II

Compact model for expressing turn-off waveform for advanced trench gate IGBTs is proposed even under high current density condition. The model is analytically formulated only with device structure parameters so that no fitting parameters are required. The validity of the model is confirmed with TCAD simulation for 1.2–6.5 kV class IGBTs. The proposed turn-off model is sufficiently accurate to calculate trade-off curve between turn-off loss and saturation collector voltage under extremely high current conduction, so that the model can be used for system design with the advanced trench gate IGBTs.     

4.5-kV injection-enhanced gate transistors (IEGTs) with high turn-off ruggedness

Although high blocking voltage insulated gate bipolar transistors (IGBTs) have wider safe operating areas (SOAs) than do gate turn-off thyristors, a failure problem remains at turn-off transient. The purpose of this paper is to clarify the mechanism of failure at turn-off transient and to develop a high-voltage injection-enhanced gate transistors (IEGTs) with wide SOA at turn-off transient [wide reverse-biased SOA (RBSOA)]. We discuss this destruction mechanism in detail on the basis of comparison of experimental results with calculated results obtained by an analytical model considering dynamic avalanche generation. These results lead to the conclusion that the design of the n-emitter and the control of avalanche generation onset are key parameters for realizing high ruggedness of high-voltage IEGT. Based on the proper design of the n-emitter and the gate driving condition, a high-voltage and high-current 4.5-kV IEGT with wide RBSOA, keeping low saturation voltage and low turn-off switching loss, has been successfully developed.