多绕组高频变压器隔离式多电平变换器研究

为在高压大功率变换领域中省去工频变压器,并实现隔离、功率平衡和能量双向流动,提出了一种高频变压器隔离式级联型多电平变换器拓扑。级联H桥整流器和级联型逆变器的各个直流母线与采用多绕组高频变压器的隔离单元相连接,可通过多绕组变压器简单地实现各级负载不均衡时的功率平衡。本文给出了多绕组高频变压器隔离式多电平变换器的拓扑结构,并给出了包括级联H桥整流器控制和高频隔离单元控制的控制策略。实验结果验证了本文提出的拓扑和控制策略的正确性。     

适用于带开关电源电焊机的现代功率器件

在电焊中,需要可以为低的输出电压提供大断续直流电流的电流源。过去,在变压器原边电路中使用带抽头的变压器,在变压器副边电路中使用抽头变换器和功率整流器就足够了。如今,通过采用最先进的快速功率半导体,如MOSFET和IGBT,焊接电流可以精确受控。     

重复控制的单相高频隔离PWM整流器

为解决高频隔离整流器半导体开关电压应力大的问题,并提高并网电流的控制性能,提出一种双向功率流两级高频隔离整流器的调制和控制方法,并对其工作模态和软开关条件进行详尽的分析。该整流器由副边的全桥、高频隔离变压器和原边的周波变换器构成,并加入钳位电路消除变压器原边的电压过冲和振荡。设计其调制方法,建立其数学模型,并采用复合重复控制的双闭环策略进行输出电压和电网侧电流的高性能控制。周波变换器和钳位电路均实现了零电压开关,副边全桥电路部分实现零电压开关。制作了1 kVA的实验样机,实验结果验证了调制方法和控制策略的有效性。该高频隔离整流器结合了常规单相PWM整流器和高频隔离变换器的特性,其更有输出电压范围更广,双功率流、高功率密度和电网侧电流质量高且功率因数可调节等特点,非常适合电动汽车充电领域。     

多谐振控制零电压开关单相高频隔离逆变器

针对双功率方向高频隔离变换器开关电压应力大、难以实现软开关等问题,为了提高输出电能质量,提出一种双向功率流两级高频隔离逆变器的调制及其控制方法,并对其各个工作模态和电路软开关条件进行详细的分析.该逆变器由原边的H桥、高频隔离变压器和位于副边的周波变换器构成,并加入钳位电路消除变压器副边的电压过冲和振荡.设计该逆变器及其配套钳位电路的调制方法,建立其数学模型,并采用多谐振控制器进行输出电压的精确控制.周波变换器和钳位电路均实现了零电压开关,讨论了原边中全桥电路的零电压开关条件.制作了1 kVA的实验样机,分别在电阻负载和整流器负载下进行了实验,测得总谐波畸变率分别为0.544％和3.1％,验证了调制方法和控制策略的有效性.     

回馈式级联型变频器PWM整流控制及其谐波分析

研究了回馈式H桥级联型多电平变换器,利用移相变压器的二次侧漏抗代替PWM整流器的输入电抗器,采用比例积分加谐振(PIR)的调节方法,设计了电网电压定向控制的PWM整流器双闭环控制策略。同时,文中给出了H桥的功率单元拓扑结构、PWM整流器的数学模型及控制策略,对PIR调节器原理、功率单元及网侧电流谐波进行了分析阐述。通过实验,验证了移相变压器消除谐波的作用,以及控制策略对直流母线电压稳定的有效性,实验结果表明PWM整流器及其控制策略在电动机加速、减速过程中,表现出良好的四象限运行性能。     

基于三相-单相电力电子变压器的牵引供电系统负载不平衡、无功和谐波潮流分析

将三相-单相电力电子变压器应用于贯通式同相供电系统,对比计算了传统变压器、电力电子变压器的单相侧和三相侧之间负载不平衡、无功和谐波的潮流关系。基于三电平电路研究了隔离DC-DC变换器和多模块级联整流器的控制方法:整流器采用有功无功解耦控制,实现了三相网侧单位功率因数运行;隔离DCDC变换器采用双边三电平控制,减小了流过中频变压器电感电流有效值。仿真和实验结果验证了基于三相-单相电力电子变压器的贯通式同相供电系统可有效消除负载不平衡、无功和谐波对三相电网电能质量的不良影响,系统动静态性能良好。     

基于多绕组变压器隔离型变换器的链式STATCOM研究

提出了一种新的STATCOM主电路拓扑结构,它由N个级联的多绕组变压器隔离型变换器构成,每个多绕组变压器隔离型变换器由1个多绕组变压器和M个变换器构成,每个多绕组变压器的M个副边绕组与M个变换器相连,M×N个变换器公用一个电容。所提结构由于同时避免了单个器件的串联和并联,从而有效地提高了装置的可靠性;采用载波移相的SPWM调制策略可同时优化输出电压和输出电流的谐波性能。所采用的多绕组变压器的副边绕组之间不需要错相位,错相位由变换器的控制器完成。给出了一种恒无功运行模式下的解耦控制方案。基于Matlab/Simulink的仿真结果证明了所提结构的良好性能和所提控制策略的有效性。     

使用六绕组隔离变压器的大电流整流器研究

为提高整流器的电流输出能力,设计了一种基于六绕组隔离变压器的大电流整流器。该整流器使用六绕组隔离变压器作为移相变压器,隔离变压器的原边绕组采用三角形联结,副边绕组相互独立,输出3组相位依次相差120°的单相电压,分别为3组单相整流桥供电,可有效增大电流输出能力。理论分析、仿真及实验结果表明,该大电流整流器的输入侧和负载侧的电能质量与传统的双反星形整流器相同,但电流输出能力为双反星形整流器的1.5倍;另外,该大电流整流器所用隔离变压器的容量要小于双反星形整流器所用变压器的容量,这在一定程度上可以提高该整流器的功率密度。     

一种变压器反极性连接的双向DC-DC变换器

本文对一种隔离变压器反极性连接时的双向DC-DC变换器进行了研究。隔离变压器副边绕组极性的不同选择可使变换器分为正向连接型和反向连接型两种。本文介绍了反向连接时变换器的工作原理和特点。研究了传递的功率与占空比、移相角以及两边电源电压的关系。比较了两种不同的连接方式对变换器开关器件电流电压应力的影响。在保持50%占空比不变、采用移相调节功率时,两种拓扑结构具有相同的性能。实验结果验证了这种反向极性连接的变换器也可以正常地工作于占空比调节方式下。     

一种低耐压中性线谐波治理电路原理及实现

介绍了一种新型低耐压中性线谐波治理装置的主电路结构，并对其工作原理进行了分析。该结构基于零序谐波电压互感器思路。采用单相桥式逆变电路，其输出通过变比为1：1的隔离变压器与系统相连，不会增加逆变器承受的电流。隔离变压器原边采用Y0接法，副边采用开口三角形接法，逆变器无需承受系统基波电压，只承受零序谐波电压和不平衡电压，降低了主电路承受的电压；采用的器件少且电压等级低，节约了成本；直流侧电容由三相二极管整流器充电。并且由于补偿零序谐波，直流侧与交流侧交换的有功功率很小，因此无需对直流侧电压进行控制。研制了一套试验装置，通过实验结果分析可以看出，该电路具有耐压低、结构和控制简单、运行可靠等优点。     

一种简化T型滤波器的双馈风力发电整流器

在现今风力发电领域,大多采用双馈变速恒频风力发电机,配合两电平电压型三相PWM整流器以获得较好的并网发电效果.由于PWM整流器会在电网侧产生较大的谐波电流,所以必须采用性价比较好的滤波器进行谐波治理.针对双馈风力发电系统的变流器,提出一种简化滤波器的整流器拓扑结构和控制方法,分析了此方法的优点,并且进行了仿真和实验验证.通过仿真和真实系统运行检验了这种简化滤波器整流器的合理性.     

基于混合开关的三相双重整流桥电流型脉宽调制整流器

阐明了大功率三相脉宽调制(PWM)整流器对改善电能质量的重要意义.提出了适用于大功率场合的基于混合开关的双重整流桥电流型PWM整流器拓扑.该整流器采用晶闸管和可控开关管组成具有PWM功能的三相电流型整流器,在降低大功率整流器成本的同时达到降低输入电网的电流谐波和控制直流侧功率的目的.分析了该整流器的工作原理,通过分析总...     

A new method of damping harmonic resonance at the DC link in a large‐capacity rectifier‐inverter system

This paper proposes a new method of damping harmonic resonance in the DC link of a large‐capacity rectifier‐inverter system, such as in rapid‐transit railways. A voltage‐source PWM converter is connected in series to the DC capacitor of the rectifier through a matching transformer, acting as a damping resistor to the DC capacitor current. No filters are needed to extract harmonic components from the DC capacitor current. This results in a quick response and highly stable damping. The relationship between the control gain of the PWM converter and the required rating is theoretically discussed. We show that the required rating is less than one‐thousandth of that previously proposed. In particular, regenerating the power consumed by the PWM converter is very important because of the large power in practical systems. Normally, an additional PWM inverter is connected to the DC bus of the PWM converter to regenerate the consumed power. The additional inverter regenerates the DC power to the AC source through a transformer. This method, however, makes the damping circuit complex, thus the proposed method for the DC‐link harmonic resonance is less practicable. In this paper, a simple and novel scheme that utilizes the DC‐link voltage of the rectifier as a DC source for the PWM converter is proposed. The excellent practicability of the proposed damping method with the novel regenerating scheme is confirmed using digital computer simulation. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(2): 53–62, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10172     

A single-phase three-level pulsewidth modulation AC/DC converter with the function of power factor corrector and active power filter

A single-phase three-level pulsewidth modulation (PWM) AC/DC converter with the function of power factor corrector and active power filter is proposed to reduce harmonic currents flowing into the power system and to draw a nearly sinusoidal current with unity power factor. The circuit topology of the adopted three-level PWM AC/DC converter is based on a conventional two-level full-bridge rectifier and one AC power switch. The control signals of the power switches are derived from the voltage balance compensator, current controller and detected operation region of mains voltage. A three-level PWM voltage pattern on the AC side of the converter in each half cycle of mains frequency is generated. Computer simulations are implemented to confirm the operation of the adopted converter with the function of power factor corrector and active power filter.     

Analysis of Harmonic Current Propagation Generated by Power Electronic Motor Controls Under Nonideal Conditions

Harmonic problem can be a serious problem in power systems. Typical case study is helpful for understanding the harmonic effects. This paper provides a novel method to establish some PSPICE macro models and apply these models to analyze the harmonics on the supply side and load side through a typical structure, which include the thyristor rectifier controlled DC motor and the induction motor fed by the PWM rectifier-inverter. Through this method, balanced and unbalanced conditions are studied. Little unbalanced degree may cause large harmonic distortion at the converter input side. Experimental results are presented to validate the simulation results.     

基于SVPWM控制技术的三相电压型整流器及其应用

传统整流方式常采用相控整流或不控整流方式.相控整流方式存在动态响应慢、深控下网侧功率因数低等缺点.不控整流方式也存在整流器从电网吸取畸变的电流,造成电网的谐波污染,直流侧能量无法回馈电网等缺点.三相电压型PWM整流器可以克服相控和不控整流的缺点,具有高功率因数、低电流谐波、电能可逆、动态响应快等优点.介绍了空间电压矢量脉宽调制(SVPWM)的控制原理及实现步骤.探讨了三相电压型脉宽调制整流器的应用范围.     

三相电压型PWM整流器在内馈斩波串级调速中的应用研究

把PWM整流技术引入到内馈斩波串级调速系统中,这样不仅可以提高串级调速系统的功率因数和减少交流侧的谐波含量,还可以有效地防止系统的逆变颠覆故障。建立了应用于串级调速系统的电压型PWM整流器的静态解耦模型,以此为基础进行了系统设计,并通过仿真验证了该方案的可行性。     

Investigation of harmonic currents and power factor on power rectifier circuits with nonequi-PWM and equi-PWM control (inductive load)

Lately, on the power rectifier circuit with semiconductor switching device, PWM control is generally employed for the purposes of reducing the harmonic currents on the dc side and improving the power factor of fundamental wave. In this case, the analysis of the current waveform becomes fairly complex. However, we express the PWM controlled voltage waveform by the step function, and can easily analyze the current waveform. We reported formerly some results of analysis about the waveform and harmonics of the current. In this paper, on the power rectifier circuit to which the nonequi-PWM and equi-PWM control are applied, we exactly calculate the harmonic currents on the dc and ac side, and the power factor by the use of the above analytical results. The characteristics of both control methods are compared on condition that each controlled factor of the load voltage is equal. These results are shown in the calculated charts. The following items can be seen from these charts on the power rectifier circuit: (1) The nonequi-PWM control can let the harmonic currents on the dc side decrease more than the equi-PWM control. But on the contrary, the harmonic currents on the ac side increase. Consequently, when the nonequi-PWM control is applied, the total power factor decreases by the increase of distortion factor of the current on the ac side. (2) The difference between the harmonic currents on the dc and ac side to both of the nonequi-PWM and equi-PWM control increases with the increase of controlled factor of the load voltage. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 117–125, 1999     

基于交错断续空间矢量调制的并联PWM变流器控制策略

并联PWM变流器可以显著增大变流器的容量并提高交流侧的电能质量,但是变流器的直接并联容易在其内部产生环流,从而导致变流器损耗增加甚至开关器件损坏.本文以三相PWM整流器并联系统为例给出了环流的数学模型,该环流是一个存在于零轴的带直流偏移量的环流.针对环流问题,本文通过建立并联系统的小信号模型分析确定了零序电流环的设计,并采用了交错断续空间矢量调制方法来消除和抑制其对整个系统的影响.通过该方法,环流可以用dq轴分量表示,并通过功率因数校正(PFC)电路的电流环加以抑制.最后的仿真和实验验证了本文控制策略的有效性.