A multiple-switch high-voltage DC-DC converter

Series connection of power devices has evolved into a mature technique and is widely applied in HV DC power systems. Static and dynamic voltage balance is ensured by shunting individual devices with dissipative snubbers. The snubber losses become pronounced for increased operating frequencies and adversely affect power density. Capacitive snubbers do not exhibit these disadvantages, but they require a zero-voltage switching mode. Super-resonant power converters facilitate the principle of zero-voltage switching. A high-voltage DC-DC power converter with multiple series-connected devices is proposed. It allows the application of nondissipating snubbers to assist the voltage sharing between the multiple series-connected devices and lowers turnoff losses. Simulation results obtained with a circuit simulator are validated in an experimental power converter operating with two series-connected devices. The behavior of the series connection is examined for MOSFETs and IGBTs by both experimental work with a 2 kW prototype and computer simulation. Applications can be found in traction and heavy industry, where the soft-switching power converter is directly powered from a high-voltage source     

高压IGBT制造技术的最新动向

阐述了当前２．５～４．５ｋＶ高压ＩＧＢＴ的最新制造技术和典型器件结构，认为高压大电流ＩＧＢＴ器件的开发成功将为未来电力电子技术的发展提供新的机遇和挑战。     

Suitability and optimization of high-voltage IGBTs for series connection with active voltage clamping

The successful series combination of 5.2-kV high-voltage integrated gate bipolar transistors (HV IGBTs) is reported in this paper. The tail current cut-off encountered in punchthrough type HV IGBTs can represent a particularly severe handicap for the full control of the inductive voltage overshoot when connecting two devices in series. Advanced voltage clamping techniques are demonstrated, which can also limit the second voltage spike originating from the tail current cut off. It is shown in this paper, that IGBTs with a carrier lifetime profile localized at the anode side are particularly well suited for this application; the shorter the tail current interval, the lower the turn-off losses can be kept. The discussion focuses on the optimum on-state plasma distribution in punchthrough-type HV IGBTs with respect to series connection of these devices. The most recent trends in the development of HV IGBTs seem to be in line with the conclusions drawn in the discussion. Advanced future HV IGBT concepts may substantially ease the difficulties encountered in the series connection of first generation HV IGBTs as used experimentally in this paper.     

Novel buffer engineering: A concept for fast switching and low loss operation of planar IGBT

For the first time, an insulated gate bipolar transistor with a novel buffer is proposed and verified by two-dimensional (2D) mixed device-circuit simulations. The structure of the proposed device is almost identical with that of the conventional IGBT, except for the buffer layer which is formed by employing a three-step, gradually changing doping n⁺ structure. Compared with the conventional IGBT, the proposed device exhibits better trade-off relation between the conduction and switching losses. The turn-off time is halved from 9.4 μs of the conventional IGBT to 4.5 μs of the proposed device, so the operation speed of the proposed device is greatly improved. Further, the forward blocking voltage is enormously increased from 907 V of the proposed device to 1278 V of the proposed device, which is required for high power operation.     

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     

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.     

Evaluation of high-voltage 4H-SiC switching devices

In this paper, the on-state and switching performance of 4H-SiC UMOSFETs, TIGBTs, BJTs, SIThs, and GTOs with voltage ratings from 1 to 10 kV are simulated at different temperatures. Comparison with silicon devices highlights the advantages of SiC technology. SiC BJTs suffer the same problem as Si BJTs, namely the degradation of current gain with increased voltage rating which makes them unsuitable for applications above 4 kV. SiC MOSFETs dominate applications below 4 kV for their attractive conduction performance and advantages such as ease of use. Above 3 kV, SiC MOSFETs are not as attractive as SiC bipolar devices because of their high on-state voltages. In the voltage range simulated, SiC IGBTs, SIThs, and GTOs have comparable current handling ability. Considering the GTOs slow switching speed and drive complexities, IGBTs and SIThs are a better choice in the voltage range 4-10 kV. Calculations based on conduction loss and switching loss indicate that SiC SIThs are superior to IGBTs except in high-temperature and high-frequency applications where IGBTs are better. The need to provide a large gate current during turnoff and turn-off failure caused by gate debiasing, decreases the attractiveness of the SITh     

Numerical analysis of a new vertical IGBT structure with reduced JFET effect

The effect of the cell pitch on the forward voltage drops of vertical double-diffused IGBTs has been investigated. Experimental results show that the forward voltage drops in the vertical 800 V rating IGBT with cell pitch of 27, 33 and 39 μm are 3.9, 2.0 and 2.0 V, respectively, at the current density of 100 A cm⁻². Numerical simulations show that the voltage drop due to the inherent JFET region is critical to the cell pitch. A new IGBT structure is proposed based on the experimental and numerical analysis. The proposed IGBT structure reduces the JFET effect without the sacrifice of other device characteristics. Numerical simulations show that the proposed IGBT has lower forward voltage drops with the increase of the breakdown voltage and switching speed compared with conventional IGBTs.     

Low stress switching for efficiency

Power modules that turn on or off “softly,” at near zero voltage or current, promise marked gains in performance by cutting switching losses and allowing faster controls-to the likely benefit of power converters. Medium power inverters have undergone significant changes. One improvement stems from new power transistors such as insulated-gate bipolar transistors (IGBTs) with their increasing voltage- and current-carrying capabilities and increasing switching frequencies. Others derive from the use of digital signal processors and such modern control techniques as fuzzy logic and neural networks, as well as from advances in the applications of power converters that employ soft switching of the power devices. Soft-switching technologies promise marked gains in performance-lower losses and higher switching frequencies than those in the prevailing hard-switching technology. The idea is to switch a device only when the voltage across it, or the current through it, is zero. Representative soft switching converters include DC-to-DC converters rated at up to several hundred watts, as well as inductive chargers for electric vehicle batteries rated at up to 120 kW. Technologically speaking, advances in soft-switching inverters have arisen chiefly from enhancements to semiconductor power devices. Today, IGBTs lead the market for medium-power applications     

Modeling buffer layer IGBTs for circuit simulation

The dynamic behavior of commercially available buffer layer IGBTs is described. It is shown that buffer layer IGBTs become much faster at high voltages than nonbuffer layer IGBTs with similar low voltage characteristics. Because the fall times specified in manufacturers' data sheets do not reflect the voltage dependence of switching speed, a new method of selecting devices for different circuit applications is suggested. A buffer layer IGBT model is developed and implemented into the Saber circuit simulator, and a procedure is developed to extract the model parameters for buffer layer IGBTs. It is shown that the new buffer layer IGBT model can be used to describe the dynamic behavior and power dissipation of buffer layer IGBTs in user-defined application circuits. The results of the buffer layer IGBT model are verified using commercially available IGBTs     

Current state-of-the-art and future prospects for power semiconductor devices in power transmission and distribution applications

Since the first commercially viable thyristors appeared in the early 1960s, there has been a dramatic increase in the switched power ratings and versatility of high-voltage power semiconductor devices. By the mid 1970s, thyristors with switched power ratings of several MVA were being applied in high voltage dc transmission systems and static VAr compensators. The introduction, in the 1980s, of controlled turn-off devices, such as the gate turn-off thyristor (GTO) and insulated gate bipolar transistor (IGBT), broadened the application of high-voltage power devices to hard-switched converters and, by the start of the 21st century, controllable silicon power devices were available with voltage ratings of 12?kV and switched power capabilities of up to 40?MVA. A review of the current state-of-the-art in silicon high-voltage power semiconductor technology covers gate-commutated thyristors (GCT, IGCT) and IGBT devices, including the injection-enhanced IGBT or IEGT. Despite these considerable achievements, there is now mounting evidence that silicon-based power semiconductors are reaching their limit, both in terms of voltage rating and of switched power capability. The introduction of wide-band-gap semiconductor materials such as silicon carbide offers the potential to break through the voltage-switching frequency limitations of silicon, with power-switching frequency products more than two orders of magnitude higher. An analysis of the current status and future prospects for silicon carbide power electronic devices is presented, together with a case study comparing a variety of silicon and silicon carbide solutions in a 10?kV hard-switched converter application. It is shown that an all-silicon carbide switch offers the best electrical performance and lowest cost solution, in spite of higher per unit area device costs.     

The complementary insulated-gate bipolar transistor (CIGBT)-a newpower switching device

A new power switching device, the complementary insulated-gate bipolar transistor (CIGBT), is described. The device achieves very high switching speeds typical of DMOS transistors, while it maintains the low on-state resistance of the insulated-gate bipolar transistor (IGBT) on which it is based. The device incorporates a p-channel MOS transistor which acts to draw excess charge out of the base region of the IGBT as the device is turned off. Fabricated devices whose specific on-resistance is only 20% greater than that of equal-area IGBTs display turn-off times under 700 ns, while the IGBTs require 35 μs to reach the off state. The device is compared to equal-area IGBTs, DMOS transistors, and IGBTs whose minority-carrier lifetime has been reduced to achieve 700-ns turn-off times     

TLM method for thermal investigation of IGBT modules in PWM mode

The insulated gate bipolar transistor (IGBT) is popularly used in high power, high frequency power-electronic applications such as motor control and inverters. These applications require well designed thermal management system to ensure the protection of IGBTs. Choice simulation tools for accurate prediction of device power dissipation and junction temperature become important in achieving optimised designs.In this paper, thermal analysis of a 1200 A, 3.3 kV IGBT module was investigated and analysed using the three-dimensional transmission line matrix (3D-TLM) method. The results show a three-dimensional visualisation of self-heating phenomena in the device. Since the comparison TLM results with the analytical solutions do not exist for this IGBT module, we use the MSC.NASTRAN tool to find the similar range of the temperatures. Results are compared.Typically, IGBT is used in a three-phase inverter leg where the control signals are generated via PWM scheme so, the prediction of the temperature rise is important in the pulse operation conditions for the IGBT device. A view of the dynamic thermal temperature rise is obtained with 100 W-step pulse dissipation applied at IGBT chips. The temperature rises are calculated using TLM method during the PWM load cycles. Simulations give clear indications of the importance of the spreader material and are helpful in selecting the proper one.TLM has been successful in modelling heat diffusion problems and has proven to be efficient in terms of stability and complex geometry. The three-dimensional results show that method has a considerable potential in power devices thermal analysis and design.     

一个快速高压固态开关的设计及实现

大多数固态功率开关中，开关速度会随着电源的增加而降低。基于这种原因，有很多方法在高功率下可获得合适速度。其方法之一是中压和额定电流大功率开关串联或并联的开关结构。这篇文章研究了不同型号的快速固态功率开关并选择IGBT作为开关单元。为了模拟，设计了IGBT的微观工作模型。最后，采用了8个IGBT串联的原型固态开关结构并且在7KV和600A下测试，其开通时间少于150纳秒。     

Transformerless capacitive coupling of gate signals for seriesoperation of power MOS devices

A reliable configuration for triggering a series string of power metal oxide semiconductor (MOS) devices without the use of transformer coupling is presented. A capacitor is inserted between the gate and ground of each metal oxide semiconductor field effect transistor (MOSFET), except for the bottom MOSFET in the stack. Using a single input voltage signal to trigger the bottom MOSFET, a voltage division across the network of device capacitance and inserted capacitances triggers the entire series stack reliably. Design formulas are presented and simple circuit protection is discussed. Simulation shows reliable operation and experimental verification is presented, Application of the method is applied to series insulated gate bipolar transistors (IGBTs)     

Analysis on the difference of the characteristic between high power IGBT modules and press pack IGBTs

The insulated gate bipolar transistor (IGBT) has been widely employed in such applications as alternate current motors and inverters for its lower driving power and lower on-state voltage. IGBT modules and press pack IGBTs are the most commonly used packaging for high-voltage and high-power-density applications. The difference in the packaging style and working conditions between IGBT modules and press pack IGBTs creates distinctions in, for instance, the thermal characteristics and reliability. Those distinctions lead to different applications and working conditions. In this paper, the development of IGBT devices has been reviewed, including the distinction of IGBT modules and press pack IGBTs in packaging style. Most importantly, the thermal and reliability characteristics have been compared in detail and the applications that are most suitable for IGBT modules and press pack IGBTs were outlined. The comparison of the thermal characteristics, reliability and applications provides guidance for users to take full advantage of the devices according to their requirements.     

为电流探头分析设计的60ns上升时间的1kA脉冲电流源

在电力电子应用方面，大电流和高带宽电流探头的运用是必须的，以便分析现代快速开关功率半导体器件的开关特性。目前普通的电流探头基本上可以达到每微秒10KA或更高。为了检测电流探头的可用性，象取样电阻、电流变换器或者Rogowski传感器，设计了电流源，它能产生以60纳秒上升的平顶为1KA脉冲。     

Investigation of the power dissipation during IGBT turn-off using a new physics-based IGBT compact model

New compact models of the IGBTs (both non-punch through IGBT (NPTIGBT) and punch-through IGBT (PTIGBT)) are presented in this paper. The models are implemented in the SABER circuit simulator and used for a study of IGBT anode current and voltage characteristics during a device turn-off (clamped inductive load circuit with gate controlled turn-off), since these parts of the transient characteristics essentially predict the power dissipation (V×I) inside the device. It is shown that PTIGBTs are faster than NPTIGBTs, this becoming more apparent at higher clamp voltages.