摘要
为解决多电平变流器中共模电压随电平数增加幅值增大的问题,以五电平桥式中点箝位变流器为例,分析共模电压的产生机理,并提出一种基于改进型空间矢量脉冲宽度调制的共模电压抑制技术。将五电平桥式中点箝位变流器等效为两个三电平中点箝位变流器的组合,原参考电压矢量可分解为两个小的电压矢量。五电平空间矢量脉冲宽度调制也被分解为两个三电平空间矢量脉冲宽度调制。为抑制其共模电压,其中一个三电平变流器采用零共模电压空间矢量脉冲宽度调制策略,另一个三电平变流器则按传统空间矢量脉冲宽度调制策略进行调制。对比分析并仿真研究现有两种调制策略与改进型空间矢量脉冲宽度调制策略下五电平桥式中点箝位变流器的共模电压和直流电压利用率。理论分析和结果证明变流器的共模电压最大值比传统SVPWM(space vectorpulse width modulation)下降了60%,直流电压利用率比零共模电压策略升高了4%,说明在共模电压得到有效抑制的同时,保持了较高的直流电压利用率。
The more level of inverter is,the higher the amplitude of common-mode voltage is.And the more severe its harm is.After investing the generation mechanism of common-mode voltage for five-level neutral-point-clamped/H-bridge inverter（NPC/H）,this paper proposes a modified space vector pulse width modulation（SVPWM） strategy to reduce common mode voltage.A five-level NPC/H inverter can be equivalent to two three-level NPC inverters using the proposed concept of equivalent inverter.The space vector plane would be divided into two three-level planes by the redistribution of the space vector plane.And through the establishment of vector decomposition rules,the reference voltage can be simplified to two three-level reference voltages to modulate the two equivalent three-level NPC inverters for resynthesizing the original reference voltage.Therefore,a five-level SVPWM control strategy with high complexity can be accomplished briefly by two separated three-level SVPWM control strategy.Besides,one equivalent inverter always operates with zero common mode voltage for suppressing CMV and the other one operates with conventional three-level SVPWM control.Theoretical analysis on DC supply voltage utilization and maximum amplitude of CMV（common-mode voltage） was carried out,and it was compared with the traditional SVPWM and zero CMV.Theoretical analysis and simulation results show that the common-mode voltage of five-level inverter decreases about 60% comparing with traditional SVPWM,and the DC voltage utilization ratio increases about 4% comparing with zero common mode voltage strategy.The results validate the proposed SVPWM strategy can suppress the common mode voltage of inverter and maintain the better character of DC voltage utilization ratio.
出处
《电机与控制学报》
EI
CSCD
北大核心
2012年第11期52-57,共6页
Electric Machines and Control
基金
国家自然科学基金(51067004)
关键词
多电平
共模电压
五电平桥式中点箝位变流器
空间矢量脉冲宽度调制
等效
电压利用率
multilevel
common mode voltage
five-level neutral-point-clamped/H-bridge inverter
space vector pulse width modulation
equivalent
DC supply voltage utilization
