Three-Phase Modular Multilevel Converter With Optimized Capacitor Sizing for Low-Voltage Applications

High capacitance requirement is a major concern of modular multilevel converters (MMCs) when applied to medium- or low-voltage systems. This article presents the design procedure and development of a modified MMC topology for low-voltage applications. With respect to the conventional MMC topologies, the proposed structure is designed and optimized to have a relatively low capacitance requirement. The switching states, modulation, control, and design procedure of the different parameters, including submodule capacitor and arm inductor, are investigated in this article. Moreover, the control scheme is presented to achieve regulation of the output voltage and the circulating current. The outcomes of this study are verified by simulation and experimental results.