模块化多电平逆变器共模电压研究

Study of Common Mode Voltage in Modular Multi-level Converter

对模块化多电平逆变器(MMC)中,开关动作和子模块电容电压波动产生的共模电压展开研究。先用双傅立叶分解法推导了载波移相调制方式下各个子模块的PWM波频域表达式,然后对子模块电容电压的低频特性进行分析,最后分析了共模电压的成份及来源,并给出计算式。在Matlab中搭建了模型,通过仿真对理论分析进行验证,对比结果证明了理论分析的正确性。

This research was launched aiming at the common mode voltage causing by the switch shifting andthe voltage ripple of capacitor in sub-module when operating. First,double Fourier method was used to give the PWMwave presented in frequency domain using carrier phase shift modulation;then,the characteristics of low frequencyvoltage ripple of capacitor in sub-module was analyzed;finally,the components and its source of common modevoltage were analyzed,the calculation method of the components was also given. A model was built in Matlab to provethe analysis,and the result shows that the analysis is right.