基于阶梯波调制的MMC电容电压平衡控制方法对比研究

针对阶梯波调制策略应用于模块化多电平变流器(MMC)时子模块电容电压的均衡问题,分析并比较两种典型的电容电压平衡控制方法。结合基于阶梯波调制策略的MMC工作机理的分析,详细论述开关序列轮换法和排序冗余选择法的基本思想和实施细则,给出两种控制方法在电压平衡效果、开关频率、算法结构和硬件要求四个方面的比较结果。依据相同的主电路参数,建立基于开关序列轮换法和排序冗余选择法的阶梯波调制MMC仿真模型和物理实验平台。仿真和实验结果表明,开关序列轮换法稳态表现良好,而排序冗余选择法有较强的暂态调节能力,后者具有较好的实用性和可靠性。

Comparative analysis on capacitor voltage balance control strategies for staircase modulated modular multilevel converter

Aiming at solving the equalization problem of capacitor voltage of the staircase modulated mod-ular multilevel converter ( MMC) ,an analysis of two typical capacitor voltage balance control methods is conducted and the comparison between the two methods is carried out.With the analysis of operation prin-ciple of staircase modulation based MMC, the switching sequence rotation method and sorting redundancy selection methods were detailed discussed.After that, the comparison results on voltage balance effect, switching frequency, algorithm structure and hardware requirements were given.According to the same main circuit parameters, both of the switching sequence rotation method and the sorting redundancy selec-tion method were carried out on the simulation model and the physical experiment platform for staircase modulated MMC.The simulation and experimental results show that the steady-state performance of the switching sequence rotation method is excellent, while the sorting redundancy selection method exhibits astrong ability of transient regulation, and the latter consequently has good practicality and reliability.