A novel prototype of auxiliary edge resonant bridge leg link snubber‐assisted soft‐switching sine‐wave PWM inverter

This paper proposes a new circuit topology of the three‐phase soft‐switching PWM inverter and PFC converter using IGBT power modules, which has the improved active auxiliary switch and edge resonant bridge leg‐commutation‐link soft‐switching snubber circuit with pulse current regenerative feedback loop as compared with the typical auxiliary resonant pole snubber discussed previously. This three‐phase soft‐switching PWM double converter is more suitable and acceptable for a large‐capacity uninterruptible power supply, PFC converter, utility‐interactive bidirectional converter, and so forth. In this paper, the soft‐switching operation and optimum circuit design of the novel type active auxiliary edge resonant bridge leg commutation link snubber treated here are described for high‐power applications. Both the main active power switches and the auxiliary active power switches achieve soft switching under the principles of ZVS or ZCS in this three‐phase inverter switching. This three‐phase soft‐switching commutation scheme can effectively minimize the switching surge‐related electromagnetic noise and the switching power losses of the power semiconductor devices; IGBTs and modules used here. This three‐phase inverter and rectifier coupled double converter system does not need any sensing circuit and its peripheral logic control circuits to detect the voltage or the current and does not require any unwanted chemical electrolytic capacitor to make the neutral point of the DC power supply voltage source. The performances of this power conditioner are proved on the basis of the experimental and simulation results. Because the power semiconductor switches (IGBT module packages) have a trade‐off relation in the switching fall time and tail current interval characteristics as well as the conductive saturation voltage characteristics, this three‐phase soft‐switching PWM double converter can improve actual efficiency in the output power ranges with a trench gate controlled MOS power semiconductor device which is much improved regarding low saturation voltage. The effectiveness of this is verified from a practical point of view. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(4): 64–76, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20207     

Characteristics of a Current-Fed Inverter with Commutation Applied Through Load Neutral Point

A current-fed inverter which is commutated by an auxiliary commutating circuit acting through the load neutral point is investigated. The auxiliary commutation circuit consists of a single commutating capacitor and two auxiliary thyristors which are used to sequentially commutate the main thyristors. The properties of the inverter are considered for the case of an ac machine load, although the results are general and can be easily applied to cases where the inverter is interconnected with an ac power system. A ``voltage behind subtransient reactance' model results in a good prediction of the inverter operating modes for either a synchronous or an induction machine. It is shown that if conventional simple-sequential gating is used, the inverter can only operate in the motoring region, while a commutation failure will result in the generating region. This negative feature is overcome by introducing a ``delayed gating' scheme for the thyristor, which allows the peak commutating capacitor voltage to be actively controlled; thus, commutation for various inverter conditions is maintained. A scheme of parallel commutation circuits is introduced which allows the value of commutating capacitance to be actively selected as a function of load condition. While the main thyristors are subjected to approximately 50 percent more applied voltage compared to the more conventional auto-sequential type of inverter in present use, the thyristors may be rectifier grade since a substantial di/dt inductance is naturally provided by the motor leakage inductance: a fact which means that negligible snubber components are needed compared to the auto-sequential circuit.     

Newly proposed hybrid resonant commutation bridge‐leg link snubber‐assisted three‐phase ZVZCS‐PWM soft‐switching inverter

This paper presents the newly proposed hybrid resonant commutation bridge‐leg link (HRCB) snubber circuit which can achieve zero voltage and zero current soft‐switching commutation for single‐phase and three‐phase voltage source‐type inverter, along with its unique features and operation principle. The circuit parameter design approach for the HRCB snubber circuit and the determination estimating scheme of the gate pulse timing processing which is more suitable and acceptable for single‐phase and space voltage vector modulated three‐phase voltage source inverter using the HRCB snubber circuit are described in this paper. In particular, the three‐phase voltage source soft‐switching inverter associated with the proposed HRCB circuits are evaluated and discussed from simulation and experimental viewpoints. The practical effectiveness of the HRCB snubber‐assisted three‐phase voltage source soft‐switching inverter using IGBT power modules which is based on the instantaneous space voltage vector modulation is clarified on the output voltage waveform, actual efficiency of electromagnetic noise in comparison with three‐phase voltage source‐type conventional hard‐switching inverter. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(4): 75–84, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20111     

基于交-直-交型矩阵变换器的多驱动系统的控制策略

在交-直-交型矩阵变换器(AC-DC-AC MC)的基础上，提出了一种新型的多驱动系统拓扑电路及其控制策略。拓扑电路由一个整流单元和多个逆变单元组成，多个逆变单元接在同一直流母线上，可以同时驱动和控制多路负载。PWM整流控制可以获得单位输入功率因数的正弦PWM波输入电流。在多个逆变单元中采用空间矢量调制，可以分别获得不同频率和幅值的正弦PWM波输出电压；同时通过合理插入零矢量，实现输入侧零电流换流。仿真实验结果证实了文中所提出理论的正确性。     

Analysis of PWM current source GTO inverter with PWM-controlledthyristor rectifier for induction motor drive

With the application of an energy rebound circuit for the pulsewidth modulation (PWM)-controlled rectifier, an improved current source gate turn-off thyristor (GTO) inverter system capable of producing sinusoidal inputs and outputs is presented. The energy rebound circuit in the inverter is used to turn off the thyristors in the rectifier for applying PWM control techniques and also to clamp the spike voltage produced in the inverter circuit. The principles and circuit operations of this system are described in detail, and requirements for PWM control of the rectifier are investigated. The conditions for satisfying the requirements of the energy rebound circuit are analyzed by experimental and theoretical methods. The PWM-controlled current source GTO inverter system is used to drive an eight-pole 400 Hz 5.5 kW induction motor. Analytical and experimental results, as well as the characteristics of the motor drives, are given     

A Versatile Commutation Circuit for PWM Inverters

A new commutation circuit, especially suitable for pulsewidth-modulated (PWM) inverters, is described. The circuit does not require precharging of a commutation capacitor and is therefore ready for commutation at any time. This results in a very flexible and possibly programmable commutation control. Further-more, during PWM operation, the number of commutations per cycle can be halved when compared with other existing circuits. This further improves the circuit efficiency which is already one of the highest available on a per commutation basis. By slightly modifying the basic circuit, one obtains an inherent fuseless protection during shoot-throughs or short circuits. The basic circuit with all its modifications is presented. A detailed circuit analysis is given, together with the efficiency evaluations. The detailed design procedure is outlined and the experimental results obtained on an actual inverter are included.     

Improved current source GTO inverter-fed induction motor driveswith PWM-controlled thyristor converter

An improved current-source GTO (gate turn-off) inverter system for driving an induction motor at high frequency was developed. This system is composed of an inverter using GTOs and a PWM (pulsewidth-modulated)-controlled thyristor rectifier. The energy rebound circuit in the inverter is used to turn off the thyristors in the rectifier and to apply PWM control techniques. This circuit plays an important role in the treatment of reactive power in a load. The capacitors connected to the AC input terminal to improve PWM control also function as a filter. Thus, the waveforms of the input voltage and current become almost sinusoidal. Principles and circuit operations of the rectifier section are described in detail. The current-source GTO inverter is used to drive a 5.5 kW induction motor. The experimental waveform and characteristics for the tested motor drives are given. It is shown that the harmonic components of the input voltage and current are eliminated or reduced by using the PWM control technique without spoiling the inherent characteristics of the current-source GTO inverter     

Development of a high-efficiency inverter without audible noise

The proposed inverter combines two methods which can significantly decrease the on-state and switching losses. The first method, using a current transformer and a single transistor, makes possible the reduction of the on-state loss to less than one-third of the usual Darlington transistor. The second method, using an auxiliary commutation IGBT in parallel with the transistor, makes possible zero-voltage switching, resulting in no switching loss. To realize higher inverter efficiency, a snubber and its loss recovery circuit are employed. Three-phase inverters were fabricated experimentally to evaluate our idea. Device volume and weight can be decreased to one-third those of a conventional three-phase inverter, and an efficiency of 98.0% from 5 kW to 20 kW is obtained at a switching frequency of 16 kHz. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(1): 62–69, 1997     

Analysis and Optimization of a Complementary Current Impulse Commutated Inverter

The operation, analysis, and optimization of a complementary impulse commutated inverter using current impulse instead of voltage impulse for commutation is presented. The operation of the inverter is described, and its salient features are discussed in relation to other commonly used inverters. The trapped energy in the commutation circuit is studied, and methods of feeding back or dissipating this energy are discussed. The optimum operating parameters are derived analytically. This inverter combines the good features of auxiliary commutation with the simplicity of complementary commutation. The advantages of this inverter in pulsewidth modulated (PWNM) inverter applications are examined. A three-phase PWM inverter with a novel switching strategy to minimize losses is designed, tested, and experimental results are presented.     

基于Buck变换器的无刷直流电机转矩控制仿真

无刷直流电动机（BLDCM）存在转矩脉动的突出缺点，提出了一种基于直流环节电压控制和模糊PID控制器的新型混合控制策略，以抑制无刷直流电机的转矩脉。电路拓扑包含功率因数校正降压转换器和逆变器。降压转换器通过控制直流电路电压来降低换向转矩脉动，使用模糊PID控制器和脉冲宽度调制（PWM）技术的逆变器在导通区域提供适当的电流。 Buck变换器降低了通过控制直流环节电压换向转矩脉动，逆变器使用模糊PID和PWM技术提供导通区域的电流。该方法能够消除传导区转矩脉动,削弱换相区转矩脉动，仿真结果表明，该策略具有功率因数校正功能，可有效抑制转矩脉动，提升电机运行的鲁棒性。     

Current-Source Double DC-Side Forced Commutated Inverter

DC-side commutated inverters are very attractive due to their simplicity and efficient use of the commutation circuit. A new current-source commutated inverter of this type equally applicable to both single and multiphase bridge configurations is considered. Simultaneous turn-off of all bridge thyristors allows ample possibilities for programming the commutation sequence. The behavior of a threephase bridge is analized, and the optimum values of the commutation components are obtained. Guidelines for analysis under any commutation condition, as well as general programming rules and suggestions for snubber design are given. Results obtained in a 8-kVA variable speed drive prototype are shown and discussed.     

基于IMC多机传动系统的控制策略研究

针对传统交直交变换器多机传动系统中间直流环节存在大电感或大电容而使其体积大,笨重等的问题,采用了一种新颖的基于间接矩阵变换器IMC的多机传动系统电路拓扑。其结构紧凑,体积小,重量轻;整流级采用两段式PWM调制策略,可获得单位功率因数的正弦输入电流,多个逆变级均采用空间矢量调制,实现各个逆变级的独立控制,获得不同频率和幅值的正弦电压。在这种调制策略的基础上,分析了零矢量重叠PWM分布方式对输入输出性能的影响,它可以实现整流级电路的零电流换流,减少了逆变级的开关次数,极大地降低了开关损耗,提高了变换器的效率。仿真结果表明:采用零矢量重叠的调制策略可以减少输出电压电流的谐波含量,能够有效改善传动系统的动态和稳态性能。     

Improvement of power conversion efficiency of soft‐switching inverter in range of low output power by adjustable dead time control

The power conversion efficiency of soft‐switching inverters can be improved by using loss‐less snubber commutation; however, the main switches of the inverter fail in zero‐voltage turn‐on when the output current is small. As a solution to this problem, adjustable dead time control in a loss‐less snubber commutation according to the magnitude of output current has been proposed. Adjustable dead time control achieves zero‐voltage turn‐on of the inverter main switches in a loss‐less snubber commutation in the range of low output current; however, waveforms of the output current of the inverter become distorted. In this paper, we propose a scheme for adjustable dead time control with dead time compensation for soft‐switching inverters. The effectiveness of the proposed control scheme is verified by experiments. Experimental results demonstrate that when the proposed control scheme is adopted, the power conversion efficiency in the range of low output power improves up to about 3% and the THD is improved within 3%. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(1): 57–64, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21282     

A new regenerative snubber circuit for large-capacity three-level GTO inverter systems

Increase in the capacity of GTOs has made remarkable progress in recent years. At present, 4.5-kV, 4.0-kA GTOs are commercially available, and 6.0-kV, 6.0-kA GTOs made from 6-inch silicon wafers are appearing. The 6-inch GTOs will be applied to our three-level GTO inverter system. In order to apply GTOs to voltage-source inverters, snubber circuits are necessary for limiting on the turn-on di/dt and turn-off dv/dt. To realize high efficiency of the system, regenerative snubber circuits are often applied. A conventional circuit applied to three-level GTO inverters had the problem of long paths created for snubber circuits of the inner GTOs. Another circuit using a current transformer for recovering the energy trapped in the snubber circuits of the inner GTOs has been presented. In this paper, a new regenerative snubber circuit is proposed, which is more suitable for three-level GTO inverter systems with many phase-legs. By applying the snubber circuit, all snubber energy generated by each GTO switching can be regenerated to the dc link. In addition, high current turn-off performance of both the inner and the outer GTOs is verified by several successful experimental results using 6-inch 6.0-kV, 6.0-kA GTOs. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(2): 41–48, 1997     

整流侧控制方式对特高压直流输电系统换相失败影响研究

特高压直流输电系统发生换相失败时,会引起直流电压和直流电流突变,严重影响直流系统的安全稳定运行。控制系统是特高压直流输电系统的核心部分,其控制方式对系统的输出响应有重要影响。分析特高压直流输电系统换相失败的原因,介绍整流侧的控制方式,建立了云广特高压直流输电系统仿真模型,研究云广特高压直流输电系统整流侧采用定电流控制方式和定功率控制方式对换相失败的影响。仿真结果表明：当逆变侧换流变压器变比K改变时,整流侧采用定电流控制与采用定功率控制相比,系统发生换相失败时的临界变比较大;当逆变侧交流母线发生三相对称接地故障、两相短路故障及单相接地故障时,整流侧采用定电流控制与定功率控制相比,系统不发生连续换相失败的临界电阻较小。整流侧采用定电流控制方式时,对换相失败的控制能力优于定功率控制方式。     

高性能逆变等离子切割机电源的研制

对一种大功率切割机电源的研制进行了分析,并对其主电路、工作原理、控制电路及保护系统做了较详细的介绍,成功地研制出一种高可靠性的电源。该电源采用IGBT(设计开关频率为27 kHz)逆变式全桥型电路,PWM芯片为SGS-Thomson公司的SG3525AN,工作电流为100 A,电压为150 V,具有过压、短路、过热及缓冲电路等保护功能,同时还具有较强的抗高频干扰的功能。经过实验证实该机性能稳定,电路设计合理,切割效率较高,具有较强的实用性。     

A dual thyristor converter reducing harmonics of power supply without input transformer

In general, the thyristor-controlled rectifier circuit (thyristor converter) generates a large amount of harmonics in the input power supply. Consequently, in the power system, the harmonics become more increased for larger capacity of such a converter, thus it is important to improve their harmonic characteristics. Among such converters, the double three-phase bridge converter with transformer of star and delta windings is well known. By application of such techniques, Miyairi and his group proposed a thyristor converter which has excellent harmonic characteristics. On the other hand, the multiple-connected inverter circuit without output transformer had been already proposed. However, it contains the lower-order harmonics. This paper proposes a converter which can reduce the harmonics similarly to the forementioned double-bridge converter. This circuit has the center-tapped reactor that can control the dc current like the current control of Miyairi's interphase reactor. This novel converter need not use the input three-phase transformers that usually make the cost higher. The proposed circuit has a commutation one with capacitor that is analogous to the series diode-type thyristor inverter. This circuit maintains the commutation to operate successfully with constant reverse bias time. The entire circuit operation and the commutation circuit operation are discussed and confirmed experimentally and theoretically.     

静止变频器分阶段启动控制策略研究

静止变频起动方式作为抽水蓄能机组的主要起动方式,具有启动电流可控,可频繁起动,调速范围宽等优点。转子处于低速状态时,根据机端电压计算出的转速不准确,造成传统的控制方法输出的电磁转矩误差较大。本文首先介绍同步电机静止变频系统的工作原理,进一步提出了一种改进型的静止变频器控制方法。在低速阶段整流电路采用开环控制其触发延迟角,使静止变频器持续提供充足的加速转矩,转子能够按照一定的加速度上升,逆变电路采用前馈控制和反馈控制使直流电流快速上升并维持在一定水平;在高速阶段采用双闭环控制整流电路触发延迟角,逆变电路采用负载换向法实现换向。本文还给出了闭环控制器参数设计方法,提高了直流回路的稳定性以及静止变频系统的动态性能。最后通过仿真验证了该控制策略的正确性和有效性。     

An Economical Auxiliary Commutated Thyristor Three-Phase Inverter Suitable for Pulse Frequency Modulation

A new economical auxiliary impulse commutated thyristor inverter is described that is capable of providing a wide range of output ac voltage and output frequency which is useful in variable speed ac drive applications. Output voltage control is provided by a pulse frequency modulation technique, and input dc voltage to the inverter is constant and can be provided by a diode rectifier bridge. The parameters for the various circuit elements, such as commutating inductances and capacitances, di/dt limiting series thyristor inductances, and dv/dt limiting RC snubber circuits are all calculated from a dynamic simulation of a single-phase version of the inverter circuit using a software named ATOSEC I developed at the Universitédu Québec for a CDC 6400/IBM-370 computer. Experimental results obtained on a practical single-phase inverter are compared with those predicted from computer simulation and performance characteristics obtained in the case of a practical three-phase pulse frequency modulated inverter providing variable output voltage and variable output frequency are reported.     

用于光伏并网检测的电网扰动发生装置研制

作为清洁能源的太阳能发电已越来越受到重视并得到应用。根据光伏电站接入电网测试规程,研制出一种适用于光伏并网检测、具有能量回馈功能的电网扰动发生装置,实现电网电压幅值、频率扰动的模拟。该装置为背靠背双PWM拓扑结构,包括两电平PWM整流装置和三电平PWM逆变装置,整流侧采用电压电流双环控制,逆变侧采用电压单环控制,该控制策略能够准确跟踪目标参考值,响应速度快,稳态误差小。仿真和试验结果证实了该电路设计和控制策略是可行和有效的。