中文摘要：

提出新型模块化多电平拓扑，其在传统模块化多电平拓扑的每个桥臂上增加1个H桥单元，实现了输出电平数的大幅增加，H桥单元可调节输出电平数，其直流电压需为模块单元电压的一半。为了实现新型逆变电路的稳定输出．设计了包含基于载波叠加的正弦脉冲宽度调制方法和电容电压平衡控制方法的整体控制策略。最后对三相模块化多电平电路进行了仿真验证，仿真结果表明新拓扑可将输出电平数由2n＋1提升至4n＋1，控制策略实现了电容电压的稳定。新拓扑及其控制策略的有效性得到了验证。

英文摘要：

An improved topology of MMC（Modular Multilevel Converter） is presented ,which adds an H- bridge cell to each bridge to increase the output voltage levels with half of module voltage. An integrated control strategy,including the phase-disposition-based sinusoidal pulse width modulation and the capacitor voltage balance control,is designed to stabilize its output. Simulative results of three-phase MMC show that, its output voltage levels are increased from 2n＋1 to 4n＋1 and its capacitor voltage is balanced. The validity of the proposed MMC topology and its control strategy are verified.