电机驱动用新型谐振直流环节电压源逆变器

为了实现电机控制系统的高功率密度和高性能运行,必须提高逆变器的工作频率以提高功率变换器的效率和增强性能。然而,较高的工作频率会引起严重的电磁干扰和开关损耗从而导致系统整体效率降低。软开关技术被认为是解决上述问题的有效方法,结合软开关技术的优点和脉宽调制(pulse width modulation, PWM)控制的特点,提出了一种新的用于电机驱动系统的谐振直流环节软开关电压源逆变器,通过在传统硬开关逆变器的直流环节添加辅助谐振单元,实现了逆变桥开关器件的PWM软开关动作,同时,辅助谐振单元的开关也为软开关操作。文中阐述了该软开关逆变器拓扑的动作时序和动作模式,并对软开关动作时序的瞬态过渡过程进行了数学分析。对提出的新型软开关逆变器驱动无刷直流电机进行了仿真和实验研究,结果验证了电路结构和理论分析的正确性与可行性。     

一种新型无刷直流电机谐振极软开关逆变器

永磁无刷直流电机具有高功率密度、高转矩/电流比和控制简单等优势,得到了广泛应用。然而,无刷直流电机通常采用硬开关逆变器驱动,硬开关逆变器的系统效率较低,散热器的体积和重量较大,限制了大功率无刷直流电机驱动系统功率密度和性能的进一步提升。针对硬开关逆变器问题,提出了一种无刷直流电机专用的谐振极软开关电压源逆变器。通过在传统硬开关逆变器的三相输出端添加辅助谐振网络,实现了逆变桥主开关器件的零电压(ZVS)开关动作,辅助双向开关在零电流开关(ZCS)条件开通和关断。针对新型软开关逆变器,提出了一种新的脉宽调制(PWM)控制策略——TPWM TON,逆变桥上下侧开关器件轮流进行PWM调制,保持了直流母线中点电位的平衡,且使主开关和辅助开关的开关频率降到PWM调制频率的一半。对提出的软开关逆变器进行了实验研究,实验结果验证了电路结构、理论分析和控制策略的正确性与可行性。     

变压器辅助换流的谐振极型软开关逆变器

为提高逆变器的运行效率,提出了一种变压器辅助换流的谐振极型软开关逆变电路拓扑结构。该拓扑结构用高频变压器来辅助换流,没有设置串联在直流母线间的均压电容,解决了中性点电位变化问题。该逆变器的主开关和辅助开关均能完成软开关动作,并且所承受的电压都不高于直流电源电压。给出了一个开关周期内逆变器在不同工作模式下的等效电路图,详细阐述了该逆变器的工作过程,给出了软开关实现条件,并建立起了辅助电路损耗的数学模型,讨论了谐振参数对辅助电路损耗的影响。最后制作了一台4 k W的单相实验样机,实验结果表明逆变器中的开关器件都工作在软开关条件下。该有源谐振极型软开关逆变器可以有效提高效率,减小开关损耗。     

用于无刷直流电机驱动的谐振极软开关逆变器

用硬开关逆变器来驱动无刷直流电机会产生逆变器的开关损耗大和运行效率低的问题。为降低开关损耗,提出一种用于无刷直流电机驱动的新型谐振极软开关逆变器的拓扑结构,通过在传统硬开关逆变器的三相输出端添加辅助谐振电路,利用辅助电路中的高频变压器的等效电感与主开关并联的缓冲电容之间的谐振,实现逆变器主开关器件的零电压开关和辅助开关器件的零电流开关。依据不同工作模式下的等效电路图,分析了电路的换流过程和设计规则,并建立起了辅助谐振电路损耗的数学模型,讨论了谐振参数对辅助电路损耗的影响。制作了1台实验样机,实验结果表明逆变器的主开关和辅助开关都实现了软开关。该谐振极软开关逆变器能有效改善效率,降低开关损耗。     

Impact of IGBT behavior on design optimization of soft switchinginverter topologies

IGBTs operated under a zero voltage switching scheme exhibit significantly different operating characteristics from specified parameters in manufacturer data sheets. Important differences include an elevated tail current, dynamic saturation and resulting snubber dump, and a significantly higher conduction loss under moderate to high di/dt conditions. Soft switching inverter topologies of various kinds have been reported in the literature including resonant DC and AC link inverters, resonant pole inverters and many variations thereof. Loss characterization of soft switching inverter circuits reported to date is based on manufacturer data sheets, and do not reflect actual losses incurred in the circuit. Including the actual device behavior into the circuit loss calculations has a big impact on the total losses, and more importantly the trade-offs which impact the viability of a given topology at a specified operating point. This paper presents a detailed analysis of the losses in soft switching inverters and the impact on topology choice. A detailed design of a 50 kVA IGBT-based resonant DC link inverter is used as a design example, and it is seen that optimal design points and choices are significantly different from those that have been reported earlier     

Zero-switching-loss inverters for high-power applications

The development of zero switching loss inverters has attracted much interest for industrial applications. Two topologies for realizing zero switching losses in high-power converters are proposed. The actively clamped resonant DC link inverter uses the concept of a lossless active clamp to restrict voltage stresses to only 1.3-1.5 supply voltage. For applications demanding substantially better spectral performance, the resonant pole inverter (RPI), also called the quasi-resonant current mode inverter, is proposed as a viable topology. Using only six devices rated at supply voltage, this circuit transfers the resonant components to the AC side of each phase and thus requires additional inductor and capacitor (LC) components. On the other hand, the RPI is capable of true pulsewidth modulation (PWM) operation at high frequency as opposed to discrete pulse modulation operation found in resonant DC link invertors     

新型谐振直流环节软开关逆变器

为了提高逆变器的效率和性能,提出一种新型的谐振直流环节软开关逆变器。通过在传统硬开关逆变器的直流环节添加辅助谐振单元,使直流母线电压周期性地归零,实现逆变桥开关器件在零电压和零电流条件下完成切换,因此减小了开关损耗和二极管的反向恢复损耗。此外,辅助谐振单元中的开关器件可以在零电流的条件下完成开关操作。该软开关逆变器控制简单且不依赖于负载条件,过渡过程所需时间可以自由选择。文中对其工作原理进行分析,给出不同工作模式下的等效电路图和回路的参数设计方法。制作一个10kW的实验样机,实验结果验证了该软开关逆变器的有效性。     

一种PWM软开关变流器实现及损耗分析

零电流转换（ZCT）技术通过控制辅助电路的谐振,为开关器件创造零电流的开关条件.辅助电路的引入不会对主电路的控制算法产生影响,使得传统PWM控制策略能够直接应用在软开关变流器上.在分析ZCT软开关工作原理的基础上,引入的辅助电路损耗小于减少的开关损耗,ZCT技术提高变流器的整机效率.通过一台500 kVA三相ZCT软开关PWM软开关变流器互馈试验平台,完成了功率、软开关试验及不同谐振参数下的效率对比试验.试验结果表明,PWM变流器基本实现了开关器件的零电流转换,且谐振过程与理论分析基本相同,验证了谐振电流峰值与谐振周期对整机效率的影响.     

串并联谐振DC-AC变换器原理分析、建模及仿真

针对串联谐振和并联谐振直流环节变换器存在的谐振峰值电压过高,谐振峰值电流过大的缺点,提出了串并联谐振直流环节变换器拓扑概念。新型软开关变换器的主要优点为：谐振峰值电压可以控制在输入直流电源电压Ｕｓ,谐振频率高,谐振电路开关元件少,控制简单,且各种ＰＷＭ调制策略均可适用。文中分析了该变换器的荼原理,建立了系统的数学模型,进行了多种工作条件下的计算机仿真与实验研究。仿真与实验结果证明了该新型变换器工作     

A DC voltage converter with a series resonant inverter and asymmetric control of power transistors

The interest in dc converters with a series resonant inverter (resonant converters) is due to the fact that they easily realize switching of semiconductor devices at zero current and zero voltage in a device. This makes it possible to significantly reduce power losses during switching of semiconductor devices and to realize the operation of a dc–dc converter at higher frequencies with a high efficiency. In the foreign literature, many circuits of resonant converters are described and many results of experimental studies are presented. However, the theory of such converters has not been sufficiently developed and theoretical studies are conducted using approximate methods, for example, fundamental-harmonic method. This paper describes the operating principle of the power part of a dc–dc converter with a series resonant inverter with asymmetric control in the discontinuous conduction mode (DCM), when the switching frequency is less than the resonance frequency of the LC circuit. The features of symmetric and asymmetric control of the inverter’s power transistors are described, in which bipolar current pulses are formed in half of the switching period. An algorithm for asymmetric control of transistors is proposed, and a scheme for implementing this algorithm on discrete components in the form of a virtual model in the Matlab–Simulink environment is presented. The results of modeling (transient and steady-state conditions, external characteristics, and other dependences), as well as the results of a comparison of the taken and theoretical (constructed from analytical relationships) characteristics, are presented.     

Development of the topology and analysis of the efficiency of voltage inverters on composite resonant switches

The paper deals with the effectiveness of composite resonant switches in a serial-parallel LCC tank of a voltage-source inverter (VSI). It has been shown that these circuits operate in the duplex mode of resonant switching, in which the main switches in the output circuit of the inverter have zero voltages and currents. The use of composite resonant switches of this type requires voltage control on the capacitor of the serial LC circuit, and there are three ways to solve this problem in a circuit. Therefore, three new variants of VSIs using composite resonant switches have been developed. The integration process of a composite resonant switch in the inverter structure is based on typical variants of VSIs with resonant commutation, which show a maximum efficiency reduction of dynamic energy loss. The effectiveness of the circuit is designed with additional power losses that accrue to the inverter via the auxiliary resonant circuit in mind. Analytical estimation of additional power losses is done by mathematical calculation of the envelope of the resonant inductor current amplitude continuously changing over the period of the inverter output frequency. It has been shown that the maximum efficiency is possessed by a circuit in which the resonant inductor is designed as a reactive component with two magnetically coupled windings.     

新型无刷直流电动机专用谐振极逆变器研究

无刷直流电动机通常采用硬开关逆变器驱动.硬开关逆变器的系统效率较低,散热器的体积和重量较大,限制了无刷直流电动机驱动系统功率密度和性能的进一步提升.针对硬开关逆变器问题,提出了一种无刷直流电动机驱动系统专用的谐振极软开关电压源逆变器.通过在传统硬开关逆变器三个输出端和直流母线之间添加辅助谐振单元,实现了逆变桥主开关器件的PWM软开关动作.谐振控制开关零电流开关条件开通,零电压开关条件关断.对提出的新型谐振极逆变器进行了数学分析和仿真研究;仿真结果验证了电路结构和理论分析的正确性与可行性.     

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     

新型并联谐振直流环节逆变器控制策略

为了解决传统的硬开关逆变器存在的高du/dt、高di/dt、高开关损耗以及电磁干扰(EMI)问题,提出了一种新型并联谐振直流环节逆变器(PRDCLI)拓扑及其控制策略.该电路的主要优点是结构简单,所有功率器件均工作在零电压或零电流模式,可以实现与各种PWM策略的匹配控制.阐述了其结构组成和工作原理,重点讨论了逆变器和谐...     

三相软开关PWM逆变器载波方式的选择

详细阐述不同载波方式对PWM逆变器输出特性的影响。指出三角载波用于硬开关PWM逆变器时 ,由于死区时间的影响 ,其输出电压电流在基波频域中含有谐波成分 ;软开关PWM逆变器如果也采用三角载波 ,则不但难以控制谐振电路的起振时间 ,而且谐振电路损耗大 ,直流电压的利用率低 ;硬开关PWM逆变器采用锯齿载波调制 ,必将导致严重的电流波形失真 ;软开关PWM逆变器交替使用正负斜率锯齿载波 ,不但谐振电路的起振时间容易控制 ,而且不会导致由死区时间引起的输出电压电流波形的失真     

基于恒频PWM及多谐振技术的桥式ZCS变流器

分析及研究桥式并联谐振开关变流器存在的不足之处，针对开关功率管的导通在较大初始电流下进行，容易产生较大的di／dt导通损耗；控制回路的调节方式通过改变开关频率来实现，不利于整机电路的优化设计等^[1-3]问题。对原有电路拓朴结构提出一系列改进措施，使开关三极管实现了在零电流条件下导通及关断，变流器的控制方式实现了恒频PWM控制方式。     

一种新型的软开关正弦波PWM逆变器

为实现一种结构简单、高效、高频、低电压应力、易于控制的软开关三相逆变器控制.提出了一种新型的三相谐振极型软开关PWM逆变器,它与传统的辅助谐振极逆变器(ARCPI)不同,避免了ARCPI使用的2个大电容,没有中性点电位的变化问题.它的三相谐振电路之间是相互独立的,这就使得逆变器易于应用各种控制策略.本文选取一相电路,对其工作原理进行了分析,给出了不同工作模式下的等效电路图和最优电路设计.仿真和试验结果表明:逆变器的主开关和辅助开关都能实现软开关,谐振电路功率小,对减少电磁干扰和提高效率很有意义.     

一种新型的零电压谐振极型逆变器

为实现一种结构简单，高效，高频，低的电压应力，易于控制的软开关三相逆变器。该文提出一种新型的三相谐振极逆变器，它可以实现逆变器主开关的零电压开通，辅助开关管的零电流开关，谐振电路功率小，与传统的辅助谐振变换极逆变器(ARCPI)不同，它避免了ARCPI使用的2个大电容，也没有中性点电位的变化问题。与三角形或星型谐振吸收逆变器(RSI)的三相谐振电路之间互相耦合不同，它的三相之间是互相独立的，这就使得逆变器易于应用各种控制策略。该文选取一相电路，对其工作原理进行了分析，给出了在不同工作模式下的等效电路图，仿真和实验结果都验证了原理的正确性。     

A lossless switching technique for smart grid applications

Smart grid is an upgrade of the existing electricity infrastructure in which integration of non conventional energy sources are an integral part. This leads to the introduction of harmonics and increased switching losses in the system. Thus there is a need of loss less switching techniques for smart grid applications. Switched mode power supplies (SMPSs) are being extensively used in most power processes [1]. Developments were carried out centered on hard switched converters, where switching frequency is limited to 10 s of kHz [2]. The uses of soft switching techniques, [3], [4], [5], [6] zero voltage switching (ZVS) or zero current switching (ZCS), is an attempt to substantially reduce the switching losses and hence attain high efficiency at increased switching frequency. The soft-switching topologies belong to families namely resonant load converters [3], resonant switch converters [2], [4], resonant transition converters [5], [6], and most recently active clamped PWM converters [7], [8], [9]. The active clamp topology adds an active clamp network, consisting of a small auxiliary switch in series with a capacitance plus the associated drive circuitry to the traditional hard switch converters. The proposed paper basically deals with the design, modeling and simulation of a ZVS–PWM active clamp/reset forward converter having features like zero switching power losses, constant frequency and PWM operation, Soft-switching for all devices and Low voltage stresses on active devices due to clamping action.     

LLC resonant DC–DC converter with series‐connected primary windings of transformer

This paper proposes a zero‐voltage switching (ZVS) LLC resonant step up DC–DC converter with series‐connected primary windings of the transformer. The series resonant inverter in the proposed topology has two power switches (MOSFETs), two resonant capacitors, two resonant inductors, and only one transformer with center‐tapped primary windings. The power switches are connected in the form of a half‐bridge network. Resonant capacitors and inductors along with the primary windings of the transformer form two series resonant circuits. The series resonant circuits are fed alternately by operating the power switches with an interleaved half switching cycle. The secondary winding of transformer is connected to a bridge rectifier circuit to rectify the output voltage. The converter operates within a narrow frequency range below the resonance frequency to achieve ZVS, and its output power is regulated by pulse frequency modulation. The converter has lower conduction and switching losses and therefore higher efficiency. The experimental results of a 500‐W prototype of proposed converter are presented. The results confirm the good operation and performance of the converter. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.