Analysis and control of an MMC topology

An improved topology of MMC (Modular Multilevel Converter) is presented, which adds an H- bridge cell to each bridge to increase the output voltage levels with half of module voltage. An integrated control strategy, including the phase-disposition-based sinusoidal pulse width modulation and the capacitor voltage balance control,is designed to stabilize its output. Simulative results of three-phase MMC show that, its output voltage levels are increased from 2n+1 to 4n+l and its capacitor voltage is balanced. The validity of the proposed MMC topology and its control strategy are verified.