模块化多电平变流器输出电流谐波抑制策略

最近电平逼近是模块化多电平逆变器(MMC)常用的调制方法之一,当模块数偏少,或者调制电压过低时,输出电流会产生畸变.从原理上分析了MMC输出电流谐波畸变产生的原因,然后提出了一种抑制MMC输出电流谐波的控制方法.该方法对输出电流进行分频提取后通过PI调节器得到反相谐波电压,最后将反相谐波电压叠加到调制电压上获得总的参考电压.所提出的方法简单可行,易于实现.仿真分析和实验结果表明,采用本文所提出的方法,模块化多电平变流器输出电流的畸变得到较好的抑制.

Harmonic Suppression Strategy of Output Current for Modular Multilevel Converter

Nearest level modulation is a common modulation method for Modular Multilevel Converters (MMC). As the number of modules is few or the modulation voltage is low, the output current is distorted. Firstly, this paper theoretically analyzes the reason why the harmonic of output current is distorted in MMC, and then proposes a control method to suppress the harmonics. The method extracts the harmonics of output current, and through a proportional integral regulator, the negative harmonic voltages is obtained. Lastly, the harmonic voltages are added to the modulation reference voltage. The purpose of this method is to obtain the total reference voltage. The proposed method is simple, feasible, and easy to implement. The simulation and experimental results show that the distortion of the output current of MMC is suppressed by the proposed method.