基于载波移相的MMC控制策略研究及仿真

Research and Simulation of MMC Control Strategy Based on CPS-SPWM

模块化多电平变换器(MMC)是一种结构独特的多电平变换器,相对于传统多电平变换器,其结构简单且高度模块化、输出灵活、谐波畸变率较小,因此成为大电压高功率场合的研究热点。由于MMC的调制技术和电容电压均衡是其稳定运行的基础和关键,因此研究分析了MMC的拓扑结构和工作原理,学习了载波移相调制技术(Carrier Phase-Shifted SPWM,CPS-SPWM)的原理,并提出将载波移相调制和子模块电压均衡控制相结合的控制策略。在Matlab/Simulink里搭建了基于载波移相调制和子模块电容电压均衡控制的三相MMC仿真模型,结果验证了研究提出的控制策略在MMC中等效开关频率较高,输出电压谐波特性良好,可以很好地控制电容电压波动,是一种适合MMC的控制策略。

The modular multilevel converter(MMC)is a unique multilevel converter.Compared with the traditional multilevel converter,its structure is simple and highly modular,its output is flexible,and its harmonic distortion is small.It has become a research hotspot for large voltage and high power applications.MMC’s modulation technique and capacitor voltage equalization are the basis and key to its stable operation.Therefore,the topology structure and working principle of MMC are analyzed,and the principle of Carrier Phase-Shifted SPWM(CPS-SPWM)is studied.A control strategy combining carrier phase modulation and sub-module voltage equalization control is proposed.In Matlab/Simulink,a three-phase MMC simulation model based on carrier phase-shift modulation and sub-module capacitor voltage equalization control is built.The results verify that the proposed control strategy in the MMC has a higher equivalent switching frequency and good output voltage harmonic characteristics.Good control of capacitor voltage fluctuations is a suitable control strategy for MMC.