Pulse Width Modulation Method for Reliability Improvement of DC-link Capacitors and Power Devices of NPC Inverter

Power devices and DC-link capacitors are considered reliability-critical components in power converters. Thermal stress caused by power loss leads to wear-out failures of DC-link capacitors and power devices. Previous studies have proposed various PWM methods to reduce the thermal stress of DC-link capacitors and power devices, respectively. However, the existing methods did not consider the reduction of thermal stress of DC-link capacitors and power devices simultaneously. This paper proposes the PWM method for improving the reliability of the NPC inverter by decreasing the thermal stress of DC-link capacitors and power devices concurrently. Through the simulations and experiments, the feasibility and effectiveness of the proposed PWM method are verified.