A Novel Four-Arm Modular Multilevel Converter with High Power Density

To further improve the power density of the transformerless medium-voltage power quality control device, a four-arm modular multilevel converter (FA-MMC) topology and its control strategy are proposed in this paper. The FA-MMC is composed of four arms and arm selection switches. Half of the sub modules in each phase are multiplexed through arm selection switches to improve the utilization of the submodules. Compared with the traditional MMC topology, the proposed FA-MMC can reduce the number of submodules by 33.3%. Finally, a FA-MMC system is established on the MATLAB/Simulink simulation platform to verify the effectiveness of the proposed topology and control strategy.