A 6-switch single-phase 5-level current-source inverter

INTRODUCTION Up to now, multilevel voltage-source inverters(VSIs) (Fang, 2001) have been paid more attentionthan multilevel current-source inverters (CSIs) in thehigh-power fields. One of the most important reasonsis that inductors, as energy storage elements, have thedisadvantages of higher conducting losses and lowerenergy storage efficiency than capacitors. However,with the development of superconducting magneticenergy storage (SMES) technology (Luongo, 1996),superconducting induc…     

一种新型多电平开关变流器拓扑和控制策略研究

论文研究了几种适用于组合式电流型多电平变流器的PWM控制方法,载波相移SPWM技术,研究了多载波PWM技术在新型单相5电平电流型逆变器中的应用,研究了SVPWM技术在三相组合型5电平CSI中应用的一些基本问题。论文提出了一类新的三相分相控制式电流型多电平逆变器拓扑。这类拓扑通过三相星形负载的中性线进行解耦,逆变器的每相都可以独立控制,因此可以将多电平PWM技术应用到该类逆变器以减小输出电流谐波。文中给出了一种多载波PWM技术的数字化实现方案,并以单相5电平逆变器单元为例介绍了三相5电平逆变器的工作原理。最后建立了一个三相分相式5电平CSI的实验系统,验证了文中的结论。     

基于电流型控制的多电平单相直接式开关变流器的电路拓扑及控制策略研究

多电平变换技术主要是针对电压型逆变器,随着电力电子技术以及储能技术的发展,电流型多电平逆变器也将得到广泛应用。针对单相直接式电流型多电平拓扑开展研究,该类拓扑结构非常简单,所用开关器件和均流电感的数目非常少,逆变电路的开关器件的频率可以很低。分析了由该类拓扑组成的单相5电平、7电平变流器的工作原理,总结了变流器的拓扑构成规律,建立了单相5电平、7电平变流器的稳态平均模型,研究了它们的开关控制策略,并给出了一种通过调节输出电平宽度来消除低次电流谐波的方法。     

Novel control scheme for 3-phase PWM current-source converters under unbalanced source voltage conditions

INTRODUCTION With the development of super conductor, the PWM-CSC is being increasingly studied in recent years owing to its advanced features including sinu- soidal source current at unity power factor and high quality dc output current (Zhang and Ooi, 1993; Kazerani and Ye, 2002; Vincenti and Jin, 1994; Wang, 2000). However, under unbalanced source voltage, considerable output second harmonics and input low-order harmonics are produced due to negative sequence voltage (Vincenti and…     

高效率电流型并网逆变器拓扑及脉冲宽度调制控制策略

A novel topology of the current-source grid-connected inverter is proposed based on the immittance converter theory. A control strategy of sine-sine pulse width modulation （PWM） is studied. Compared with the traditional current-source inverter, the power frequency inductors and power frequency transformer are replaced with high frequency inductors and a high frequency transformer. Thus, the proposed inverter has advantages of small volume, low cost, low total harmonic distortion （THD）, low power losses, high power factor （PF） and simple control. Furthermore, grid voltage cannot influence output current of the grid-connected inverter and the current-source inverter with a high PF that approaches one has been realized. Finally, validity of the theory analysis and feasibility of the control scheme are shown by simulation and experimental results.     

电流滞环跟踪PWM控制的双闭环调速系统仿真

电流滞环跟踪PWM控制技术能较好地得到三相对称正弦波电流,以电流滞环跟踪PWM控制器为内环,转速外环调节器选用PI调节器,建立异步电动机双闭环调速系统.建立系统主电路及控制电路进行仿真模型,主电路由异步电动机模块、电动机测量单元模块、逆变器模块、直流电源、负载模块等组成,控制电路由转速给定信号、转速调节器、电流给定信号及电流滞环跟踪控制器等组成.仿真得到电流、转速及电磁转矩曲线,验证了方法的有效性.     

基于滑模变结构的PWM整流器系统设计

根据三相电压型PWM整流器的主电路拓扑结构,建立了整流器的数学模型;对控制系统的电流内环采用滑模变结构的控制算法,对电压外环进行PI控制,并通过Matlab/Simulink进行了仿真。从仿真结果可以看出,滑模变结构PWM整流器系统具有较好的抗干扰能力。     

一种谐波电流检测方法的分析与仿真

基波幅值分离的谐波电流检测方法算法简单、所用器件少、实时性较高,不仅适用于单相电路,也适用于三相电路。对此方法进行的仿真研究表明,该方法具有很强的理论性和实用性。     

基于动态预测的有源电力滤波器选择性谐波补偿方法

提出一种基于参考电流动态预测的选择性补偿方法。通过滑窗迭代DFT法提取与参考电流相关的特定次谐波;把动态预测算法植入补偿电流控制环节,预测下一拍的指令电流信号,并引入误差修正器提高预测精度,在此基础上计算逆变器的参考电压矢量;利用空间矢量脉宽调制法获得PWM信号,驱动三相变流器从而输出三相电压,实现选择性补偿。仿真和实验证明了该方法的正确性和可行性。     

带单相电能显示的三相四线电能表

主要介绍一种新型的三相四线电能表的设计方案,该方案采用了三相电能测量芯片SA9904和Microchip的PIC16F77作为核心器件.本文所设计的电能表不仅可以测量三相有功无功电量,而且可以分别测量三个单相有功电量,并且通过6位LED数码管,实现三相有功无功电量和三个单相电量的循环显示.     

A PAC Based Current Feedforward Control for Three-Phase PWM Voltage-Type Converter

This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC). With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed. For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle. Also, the algorithm is derived and the system principle is introduced. Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.     

新型高精度数控恒流源的设计

针对传统数控恒流源恒流校正方法复杂、调整时间较长等缺点,利用PWM技术设计了一种新型的高精度数控恒流源.该恒流源以SoC单片机C8051F020为主控芯片,采用负反馈闭环控制的方法,由PWM信号实时调整输出设定的电流.测试结果表明,该恒流源在输出电流10mA-4A范围内,控制精度为1mA,电流输出值与设定值的相对误差小于0.1%,具有精度高、控制简单、响应快、自适应能力强等特点.     

三相软开关PWM变流器电流极性检测与电流补偿方法

A novel software implementation for current polarity detection and current compensation is presented. For a three-phase zero-voltage soft-switching （ZVS） PWM converter based on phase and amplitude control （PAC）, when saw-tooth carriers with alternate positive and negative slopes are adopted, the positive or negative slopes are chosen according to the phase current polarity. Since polarity reversal causes current distortion, current at the instant of reversal should be compensated for. Based on the characteristic of unity power factor converter in rectification and regeneration modes, a software implementation for current polarity detection is proposed. Distortion of current zero-crossing caused by using saw-tooth carriers with alternate positive and negative slopes is analyzed, and the relevant compensation method is proposed. Experimental study with a 1.5 kW device shows that phase current has a small harmonic content and power factor is high both in rectification and regeneration modes.     

脉宽调制实验平台的研究与开发

介绍了各种脉宽调制(PWM)技术在微机上的实现方法,并从上位机、下位机以及上、下位机的通信协议三方面介绍了基于DSP的脉宽调制技术实验平台的建立。该实验平台可由上位机控制产生不同调制方式、调制频率、载波比、调制度的三相SPWM驱动波形,通过采样电路将负载上的电压、电流信号传回上位机,由上位机动态的显示负载上电压、电流信号波形。     

一种基于幅相控制方式电流前馈控制的三相PWM电压型变注器

This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC).With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed.For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle.Also, the algorithm is derived and the system principle is introduced.Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.     

浅议学习“三相异步电动机定子绕组磁动势”的方法

阐述了学习"三相异步电动机定子绕组磁动势"的方法:从单相绕组的磁动势入手,掌握其波形、数学表达式,进而用数学推导和图解法得出三相绕组磁动势。     

串联有源电力滤波器的参数选择及仿真

针对典型的三相整流电路对电网产生的影响,介绍了串联有源电力滤波器电路参数设置,探讨了易于数字化的SVP-WM跟踪算法,应用于串联有源电力滤波器内层跟踪控制中的补偿效果。并用比较的方法,重点对串联有源电力滤波器电路进行了计算机仿真分析。     

PWM逆变器的定向矢量控制策略

针对风力发电并网的优化问题。提出了三相电压源脉冲宽度调制（PWM）逆变器的定向矢量控制技术,并设计了数字控制的变换器一逆变器系统。给出了该变换器和逆变器的数学模型。提出了一种定向矢量控制的方案来实现对风能并网的控制策略。为了检验该系统的动态性能。采用MATLAB7／SIMULINK程序进行了仿真。仿真结果表明,提出的控制系统模型在不同的干扰下都展现出其良好的性能。     

基于MATLAB的电力电子仿真

随着电力电子技术的不断发展,可控整流电路在直流电动机控制、可变直流电源、高压直流输电等方面得到广泛应用。本文建立了基于MATLAB的单相桥式整流电路、三相全控桥式整流电路的动态模型,给出了仿真实例与仿真结果,验证了模型的正确性,并展现了MATLAB仿真具有的快捷、灵活、方便、直观等优点,从而为电力电子电路的教学及设计提供了有效工具。     

用于三相PWM并网逆变器的改进型幅相控制方法

In this paper, a vector regulating principle of the phase and amplitude control （ PAC ） method for three-phase grid-connected inverters is presented. To solve the problem of heavy inrush current and slow dynamic response when system starts up, the starting voltage prediction control and the current feed-forward control are proposed and used, which improve the dynamic performance of the system in the PAC. The experimental results carried out on a three-phase grid-connected inverter proved the validity of the proposed method.