Optimized Carrier Disposition Based Discontinuous Pulse-width Modulation Method for three-level NPC Converters

Three level neutral-point-clamped (3L-NPC) converter is a multilevel topology that is well-suited solution in high voltage, high frequency applications such as flexible AC transmission systems and electric vehicle drive systems. This paper is focused on a silicon carbon (SiC) based 3L-NPC for high frequency application which presents a higher switching loss and aging mismatch. In this paper, a new improved approach of the discontinuous pulse width modulation (DPWM) of 3L-NPC based on carrier disposition is presented. Based on the relationship between switching loss and power factor angle, an optimized DPWM method with minimum switching loss is proposed. The simulation and experimental results show how the optimized carrier disposition based discontinuous pulse-width modulation (OCD-DPWM) is achieved whereas the switching loss is reduced and the system efficiency is improved.