基于双SVPWM的MMC电容电压平衡控制研究

Research on Capacitor Voltage Balancing Control for MMC Based on Dual SVPWM

针对模块化多电平变换器(MMC)系统中存在的桥臂电压和子模块(SM)电容电压平衡问题,设计了一种基于双空间矢量脉宽调制(SVPWM)的MMC电容电压平衡控制策略。分别设置了两组SVPWM对三相MMC上、下桥臂独立控制,并结合使用冗余开关矢量实现了SM电容电压平衡。同时设计了SM外部电容电压平衡方法,以最小化计算负担。在SM选择过程中使用了负载电流的方向而非桥臂SM电流,降低了电流传感器数量。利用MMC试验平台对基于双SVPWM的MMC电容电压平衡控制方案进行了测试。研究结果表明,新型控制方案能有效平衡MMC电容电压。

Aiming at the arm voltage and sub?module(SM)capacitor voltage balance problem in modular multilevel converter(MMC)system,a dual space vector pulse width modulation(SVPWM)based MMC capacitor voltage balance control strategy is designed.The three-phase top and bottom arms are independently controlled with two sets of SVPWM,and the SM capacitor voltage balance is realized by using redundant switch vectors.At the same time,an SM external capacitor voltage balancing method is designed to minimize the computational burden.The direction of the load current is used instead of the arm current in SM during the SM selection process,reducing the number of current sensors.The MMC capacitor voltage balance control scheme based on dual SVPWM is tested by using the MMC test plat form.The research results show that the new control scheme can effectively balance the MMC capacitor voltage.