单相模块化多电平变流器控制策略研究

Research on control strategy of single-phase MMC

模块化多电平变流器(MMC)是一种新型的多电平拓扑,输出与子模块数相关的多电平波形。MMC具有高度模块化、易扩展、输出波形好等特点,在中高压场合具有广阔的应用前景。分析了单相MMC的拓扑结构和工作原理,并通过一定的控制策略,对子模块电容电压平衡与环流抑制进行协同控制;利用载波移相脉宽调制(CPSSPWM)技术,等效提高了开关器件的频率,从而降低其损耗。最后用Matlab/Simulink对单相MMC进行仿真实验,验证了调制策略和控制策略理论的正确性。

Modular muhilevel converter （MMC） is a new kind of multilevel topology, the output waveform of MMC is multilevel related to submodule number;With a series of advantages such as highly modular, easily extension and good output waveform, MMC has broad application prospect in high voltge system. This paper analyzes the topology and working principle of single-phase MMC,conducts cooperative control to balance capacitor voltage of submodule and restrain circulating current of the system through a certain control strategy. By using carrier phase shifted PWM （CPS- SPWM） technology,the frequency of switch elements can be improved equivalently and the loss of the elements can be reduced. Finally, doing a serious of Matlab simulation experiments of single-phase MMC to verify the validity of theories relating to modulation strategy and control strategy.