三电平逆变器共模电压分析与抑制

Common-mode voltage analysis and reduction for three-level inverter

为抑制三电平逆变器共模电压,以二极管钳位式拓扑为例,分析其共模电压产生机理并提出一种抑制共模电压的简化三电平5段式空间矢量脉宽调制算法。该算法通过选取输出共模电压幅值小的基本电压矢量参与调制来抑制共模电压。仿真和实验结果表明,所提算法将共模电压最大幅值抑制到Vdc/6,比传统一般算法、抑制共模电压的7段式、7段式算法分别减少2/3,1/2,0,且可以克服上述3种算法输出共模电压幅值随其调制度变化而变化的缺点。

In order to reduce common-mode voltage of three-level inverter,this paper takes diodeclamped topology for instance,analyzes its common-mode voltage generation mechanism and proposes a simplified common-mode voltage reduction three-level five-segment space vector pulse width modulation algorithm（SVPWM）. To reduce common-mode voltage, this algorithm selects proper basic voltage vectors to modulate. Simulative and experimental results show that, the proposed algorithm can suppress the maximum value of common-mode voltage to one sixth of DC voltage source value, and decrease respectively about two thirds, one second, zero comparing with traditional space vector modulation, seven-segment, five-segment algorithm. Meanwhile, it can overcome the disadvantage of common-mode voltage value varies with the modulation index of above three algorithms.