Common-mode voltage reduction in three-level neutral-point-clamped converters with neutral point voltage balance

This paper investigates two conflictive issues of common-mode (CM) voltage reduction and neutral point (NP) voltage balancing in a three-level neutral-point-clamped (NPC) converter. The amplitude of NP voltage variation under CM voltage mitigation scheme has been derived analytically. Various factors affecting the NP voltage have been analyzed and the solutions to achieve these two objectives simultaneously have been proposed. Simulation and experimental results have been shown to validate the analysis and proposed control scheme.