Power loss-oriented evaluation of high voltage IGBTs and multilevel converters in transformerless traction applications

The low-frequency line transformer in todays ac rail vehicles suffers from poor efficiency and a substantial weight. Future traction drives may operate directly from the mains without this transformer. A feasible concept for a transformerless drive system consists of series connected medium voltage converters applying modern high-voltage insulated gate bipolar transistors (HV-IGBTs). In a first design step, the switching characteristics and losses of 6.5-kV IGBTs are compared to 3.3-kV and 4.5-kV IGBTs which are already commercially used in traction applications. Based on the considered HV-IGBTs, the properties of multilevel converters are analyzed and their applicability to the transformerless system is evaluated. The paper focusses on a loss analysis of the converters. Reliability aspects and harmonic spectra are briefly discussed. Taking these design aspects into account, the three-level neutral point clamped converter turns out to be a reasonable solution to realize line and motor converter modules in a transformerless traction system.     

Novel zero-current-switching PWM converters

This paper presents a new family of pulsewidth-modulated (PWM) converters, featuring soft commutation of the semiconductors at zero current (ZC) in the transistors and zero voltage (ZV) in the rectifiers. Besides operating at constant frequency and with reduced commutation losses, these new converters have output characteristics similar to the hard-switching-PWM counterpart, which means that there is no circulating reactive energy that would cause large conduction losses. The new family of zero-current-switching (ZCS)-PWM converters is suitable for high-power applications using insulated gate bipolar transistors (IGBTs). The advantages of the new ZCS-PWM boost converter employing IGBTs, rated at 1.6 kW and operating at 20 kHz, are presented. This new ZCS operation can reduce the average total power dissipation in the semiconductors practically by half, when compared with the hard-switching method. This new ZCS-PWM boost converter is suitable for high-power applications using IGBTs in power-factor correction. The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM boost converter are provided in this paper to verify the performance of this new family of converters     

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     

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.     

Output plane analysis of load-sharing in multiple-module convertersystems

This paper explores the origin of the DC current-sharing problem of parallel-converter systems and the dual problem of voltage sharing in series-converter systems. Both problems may be studied by examining the output plane (output current versus output voltage) of a particular converter. It is shown that strict current source behavior is unnecessary for good current sharing in parallel-converter systems. Furthermore, a broad class of converters whose output voltage is load-dependent, i.e., those that have a moderate value of output resistance, all exhibit good voltage- and current-sharing characteristics. Such converters are often suitable for a×b arrays of converters that can meet a large range of power-conversion requirements. The output planes of discontinuous mode PWM converters as well as conventional and clamped series resonant converters are examined in detail. A simple small-signal model of the modular converter system is developed. Experimental confirmation of load sharing and the small-signal model is given for the clamped series resonant converter and the series resonant converter for various configurations of four converters     

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     

Comparison of 2.3-kV Medium-Voltage Multilevel Converters for Industrial Medium-Voltage Drives

This paper compares the expense of power semiconductors and passive components of a (2.3 kV, 2.4 MVA) two-level, three-level neutral-point-clamped, three-level flying-capacitor, four-level flying-capacitor, and five-level series-connected H-bridge voltage source converter on the basis of the state-of-the-art 6.5-, 3.3-, 2.5-, and 1.7-kV insulated gate bipolar transistors for industrial medium-voltage drives. The power semiconductor losses, the loss distribution, the installed switch power, the design of flying capacitors, and the components of an sine filter for retrofit applications are considered.     

Power electronic converter technology

The present state of the art in DC-DC, AC-DC, DC-AC, and AC-AC converter technology is presented along with their typical areas of applications. Advances made in the last decade that are finding use in industrial, commercial, and military applications are emphasized. Soft switching, in which power device switching stresses are reduced due to circuit resonances, has dominated DC-DC power conversion and some high-performance DC-AC power conversion. In the higher voltage and higher power areas, the invention and improvements of gate turnoff thyristors (GTOs), insulated gate bipolar transistors (IGBTs), and integrated gate-commutated thyristors (IGCTs) have led to other unique topologies to take advantage of these devices     

Novel zero-current-transition PWM converters

A new family of zero-current-transition (ZCT) pulsewidth-modulated (PWM) converters is proposed. The new family of converters implements zero-current turn-off for power transistor(s) without increasing voltage/current stresses and operates at a fixed frequency. The proposed converters are deemed most suitable for high-power applications where the minority-carrier semiconductor devices (such as IGBTs, BJTs, and MCTs) are predominantly used as the power switches. Theoretical analysis is verified on a 100 kHz, 1 kW ZCT-PWM boost converter using an IGBT     

Soft-switched DC/DC converter with PWM control

In this paper, a new power converter with two variations is proposed. A novel asymmetrical pulse-width-modulation (PWM) control scheme is used to control the power converter under constant switching frequency operation. The modes of operation for both variations are discussed. The DC characteristics, which can be used in the design of the power converters, are also presented. Two 50 W power converters were built to verify the characteristics of the converters. Due to the zero-voltage-switching (ZVS) operation of the switches and low device voltage and current stresses, these power converters have high full- and partial-load efficiencies. They are, therefore, potential candidates for high-efficiency high-density power supply applications     

采用辅助变压器的零电压零电流开关全桥直-直变换器

本文给出了一种新型的零电压零电流开关全桥移相脉宽调制变换器,该变换器采用IGBT为功率开关管,在传统变换器的基础上通过增加辅助变压器的方式提高了变换器的性能,通过增加正激能量恢复缓冲器和辅助电路,使变换器在各种负载以及短路工作状态下都能够保证所有开关管实现零电压零电流开关工作模式。介绍了变换器的工作原理并通过试验得到了较好的结果。     

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     

PWM DC-DC变换器功率级的采样数据模型

将PWM变换器按其工作状态,分别写出开关导通和截止时的数学模型,根据其周其工作的特点,写出其非线性采样数据模型,将该方法用于变换器功率级的建模。以连续导通电压型DC-DC变换器为例,给出了PWM变换器功率级的一种非线性和线性化的采样数据模型,并推导了考虑到控制作用延迟时由控制到输出的传递函数,满足了控制器设计的需要。     

A new configuration of single-phase symmetrical PWM AC choppervoltage controller

With the increased availability of power MOSFETs and insulated gate bipolar transistors, a new generation of simple choppers for AC inductive loads is foreseen. These new power semiconductors ease the use of forced commutations of thyristor switches to improve the supply power factor, even with highly inductive loads. The AC controllers with thyristor technology can be replaced by pulsewidth modulation (PWM) AC chopper controllers which have important advantages. In this paper, a symmetrical PWM AC chopper designed to operate with single-phase inductive loads with a reduced number of controlled switches is described. The operation as a variable voltage source of this converter is evaluated. This includes the conversion characteristics, harmonic generation, harmonic distortion factor, and input power factor. By digital simulation, these characteristics are investigated theoretically, and to correlate the measurements with theory, an experimental setup is presented to confirm the analytical analysis     

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.     

Large static converters for industry and utility applications

The emergence of high-power semiconductor devices such as insulated-gate bipolar transistors (IGBTs) or injection-enhanced gate transistors (IEGTs) and gate-commutated turn-off (GCT) thyristors or integrated gate-commutated thyristors (IGCTs) enables large static converters to expand into utility and industry applications. For instance, a ±80 kV 50 MW HVDC transmission system based on a string of many IGBTs connected in series was commissioned in 1999. This paper describes the present status of large static converters, with focus on their applications to utility and industry. The applications discussed are: HVDC transmission system, UPFC, flywheel energy storage system, pumped hydro plant adjustable speed generator, active filters for power conditioning, and steel mill drives. The paper also describes their future prospects and directions in the 21st century, including the personal views and expectations of the author     

A PFC voltage regulator with low input current distortion derived from a rectifierless topology

This paper presents an ac-dc converter topology for realization of power factor correction (PFC) voltage regulators for applications where the mains frequency is high and a low input current harmonic is required, e.g., in aircraft power systems. The proposed converter represents a minimal configuration consisting of two basic converters, which can be systematically derived from a previously proposed general synthesis procedure for rectifierless ac-dc converters. The proposed PFC converter has incorporated a control method which drastically reduces the circulating power and hence raises the efficiency to a level comparable to existing PFC converters. The proposed PFC converter can completely eliminate any crossover distortion, which can be significant for supply systems having a high mains frequency. In addition, the proposed converter allows bidirectional energy flow ensuring all inductors work in continuous conduction mode hence eliminating the distortion due to the abrupt change of dynamic response when the operating mode changes. Analysis and design of the power and control circuits will be given and discussed. An experimental system will be presented for verification purposes.     

A New Family of Zero-Current-Switching (ZCS) PWM Converters

A new family of zero-current-switching (ZCS) pulsewidth-modulated (PWM) converters which uses a new ZCS-PWM switch cell is presented in this paper. The main switch and auxiliary switch operate at ZCS turn-on and turn-off, and all the passive semiconductor devices in the ZCS-PWM converter operate at zero-voltage-switching (ZVS) turn-on and turn-off. Besides operating at constant frequency and with reduced commutation losses, these new converters have no additional current stress in comparison to the hard-switching converter counterpart. The new family of ZCS-PWM converters is suitable for high-power applications using insulated gate bipolar transistors (IGBTs). The PWM switch model and state-space averaging approach is used to estimate and examine the steady-state and dynamic character of the system. The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM boost converter, rated 1 kW and operating at 30 kHz, are provided in this paper to verify the performance of this new family of converters.     

离线式IGBT开关特性测试技术综述

IGBT功率开关器件在现代大功率变换器中的应用非常广泛,其开关特性直接影响到变换器的性能。获得实际工作条件下的开关器件特性具有重要的实用价值。如何准确测量并记录器件开关过程自然成为研究热点。文中分析了IGBT器件开关特性测试中的关键问题,总结了大功率下电流电压测量的各种方法,并对国内外的开关特性测试研究现状进行了分类和总结。     

Novel zero-voltage and zero-current-switching full bridge PWMconverter using transformer auxiliary winding

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) pulse width modulation (PWM) converter is proposed to improve the demerits of the previously presented ZVZCS-FB-PWM converters, such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high power (>2 kW) applications. The operation, analysis, features and design considerations are illustrated and verified on a 2.5 kW, 100 kHz insulated gate bipolar transistor (IGBT) based experimental circuit