基于载波移相的MMC逆变器调制方法研究

Research on Carrier Phase Shift Modulation Mode of the MMC Inverter

高压直流输电技术是研究远距离大容量输电的热点问题,而换流器控制研究是高压直流输电技术的重要环节。通过介绍MMC换流器的拓扑结构和工作原理,分析MMC换流器的调制方式,重点研究低电平基于载波移相的PWM调制方式的特点,在MATLAB环境下分别搭建5、7、9电平的MMC直流输电模型,对正弦载波移相脉宽调制(CPSSPWM)方式的特性进行了验证。结果表明,对低电平MMC换流器,PWM具有较好的逼近调制波的能力,含有较少的谐波分量及含较少的等效开关频率。

The HVDC transmission technology is a hot issue in the study of long distance and large capacity transmission while the research on controlling of converters is an important part of the technology. In this paper, through introduction of the MMC converter topology and operating principle, we analyze the MMC converter modulation mode with focus on the characteristics of the carrier phase shifted PWM modulation mode of low levels. Under the MATLAB environment, we build models of the MMC HVDC transmission of Level 5, Level 7 and Level 9 respectively and verify characteristics of the CPS-PWM modulation. The results show that for the MMC converter of low levels, the PWM has better approximation ability of modulation wave and contains less harmonic component and less equivalent switching frequency.