一种适用于全桥MMC的闭环调制策略

近年来，全桥MMC由于其具有直流故障穿越能力获得越来越广泛的关注。但是目前对于全桥MMC的研究多是使子模块工作在仅输出正电平（负电平）和零电平的工作模式下，子模块内存在常导通和常关断的开关管，导致子模块内部损耗分布不均匀，不利于散热系统的设计。为使各开关管处于相似的工作状态，优化子模块内能量分布，本文首先研究了全桥子模块的全部工作模式，基于载波移相调制方式分析了调制波交叠情况不同时子模块的输出电压。接着对单相MMC进行建模，通过理论推导得到了一种可灵活调节子模块工作状态的适用于全桥MMC的闭环调制策略。最后，利用PLECS软件对本文所提出的调制策略进行了仿真验证。

A closed loop modulation strategy for full bridge MMC

In recent years, full-bridge MMC has gained more and more attention due to its DC fault ride-through capability. However, at present, most of the research on the full-bridge MMC is to make the sub-module work in the mode of outputting only positive level (or negative level) and zero level, and there are normally on-off and on-off switches in the sub-modules, which leads to uneven distribution of internal loss of sub-modules, and is not conducive to the design of heat dissipation system. In order to optimize the energy distribution in the sub-modules, the full-bridge sub-modules are studied firstly, and the output voltage of the sub-modules is analyzed based on the carrier phase-shifting modulation. Secondly, the single-phase MMC is modeled and a closed-loop modulation strategy which can flexibly adjust the working state of the sub-modules is derived. Finally, PLECS software is used to simulate the modulation strategy proposed in this paper.