A novel nine-arm modular multilevel converter

In many applications, such as motor drives and integrating distribute power sources into a grid, there are two or more ac sources or loads. The conventional solution is to use separate modular multilevel converters, which increases cost and volume of system. Thus, a novel nine-arm modular multilevel converter is proposed in this paper, which operates as two conventional modular multilevel converters with three common arms. The proposed converter could save 25% of the number of semiconductors and 50% of the number of buffer inductor relative to two separate MMCs. Then a phase-shifted carrier-based PWM method is presented for the proposed converter. Finally, the simulation results verify the effectiveness of the proposed converter and PWM method. The proposed nine-arm modular multilevel converter is suitable in medium and large power application with two ac inputs or outputs.