Neutral point voltage balancing method and the influence of some parameters on capacitor voltage in three-level NPC converter

Abstract

This paper presented a control method for balancing capacitor voltage of three-level neutral-point-diode-clamped (NPC) converter. This control method overcomes one of the main problems of this converter, which is the low frequency voltage oscillation that appears in the neutral point. The algorithm is based on Carrier-based Pulse Width Modulation (CPWM). This paper showed the influence of power factor, modulation index and offset limit on capacitor voltage. It also presented the optimal amplitude of offset voltage in some case of power factors and modulation indexes. © Springer-Verlag Berlin Heidelberg 2014.