DC-link voltage balancing system and method for multilevel converters

摘要

A control system (50) for a multilevel converter (40) includes a differential mode current regulator (84), a neutral point (NP) controller (86) and a PWM controller (88) for generating switching pulses for the multilevel converter (40). The differential mode current regulator (84) generates reference voltage command signals based on a difference between reference current command signals and actual current command signals, and the NP controller (86) determines a modified neutral point current signal in response to a DC link voltage unbalance. The NP controller (86) utilizes the modified neutral point current signal to generate a common mode reference voltage signal. The switching pulses are generated by the PWM controller (88) based on the reference voltage command signals and the common mode reference voltage signal.