Experimental comparisons of space vector neutral point balancing strategies for three-level topology

Abstract

Three-level neutral point clamp topology has attracted applications in medium-voltage high-power drive systems. Since the topology utilizes the neutral point voltage to achieve half bus voltage withstand of power devices and three-level output voltage delivery, it is critical to balance the neutral point voltage in occasions of disturbed or even continuous unbalance load conditions. This paper proposes a couple of balancing techniques based on space vector modulation principle and experimentally compares their effectiveness against the existing method.