Voltage balancing system and method for multilevel converters

摘要

A method of operating a flying capacitor multilevel converter (60) having a direct current link (62) and a plurality of phase legs (70, 72, 74) each having a plurality of flying capacitors includes employing redundant states to balance flying capacitor voltages by charging or discharging flying capacitors. The redundant states are employed by obtaining a load current of the flying capacitor multilevel converter. If a load current value is lower than a threshold value then a capacitor current of a phase terminal capacitor is utilized to determine redundant states else a load current direction is utilized to determine the redundant states.