一种基于耦合电感的模块化多电平变流器控制

Control Strategy of a Modular Multilevel Converter Based on Coupled Inductor

对一种新型结构MMC进行了原理分析,该结构采用耦合式(带中心抽头)桥臂电感,由于上、下桥臂的严格对称性,上、下桥臂基波电流反相,耦合电感的引入在很大程度上降低了桥臂单个电感上的压降,进而有效地抑制了桥臂环流。进一步对排序控制进行改进,改进后的排序法更利于上、下桥臂的充放电平衡,同时还能进一步稳定直流侧电流。最后利用Matlab/Simulink软件搭建了每相10个模块的MMC仿真模型。仿真结果表明了耦合电感结构的优势以及提出的改进排序法的有效性。

This paper introduces a novel structure of modular multilevel converter(MMC) with a coupled(center-tapped) inductor, and describes its operating performance. Since the upper and lower bridge arms are strictly symmetric, the fundamental currents are anti-phase, then it results that the voltages on inductors are largely reduced with using the coupled inductor, which also effectively suppress the circulating current. An improved method of sorting voltages of capacitors not only is conducive to the balance of charging and discharging of capacitors, but also can stabilize the DC current. At last Matlab/Simulink simulation results of a MMC with 10 sub-modules in each phase, show the advantages of using the coupled inductor and the validity of the improved sorting method.