A novel voltage balancing method of modular multilevel converter based on phase shifted carrier pulse width modulation

In this paper, a novel voltage balancing method of modular multilevel converters (MMCs) based on phase shifted carrier pulse width modulation is proposed. The proposed method is using redundant sub-modules to balance voltages between sub-modules in the arm. This method bypass several selected sub-modules every carrier cycle based on arm current and voltage sorting result. When the arm current is charging sub-modules, the sub-modules with higher voltage are selected to bypass. Otherwise, the sub-modules with lower voltage are chose to bypass. Simulation results on a MMC based on three-phase inverter show validity of the proposed method.