A High Efficiency and Low Cost ANPC Inverter Using Hybrid Si/SiC Switches

Abstract

This paper presents a performance investigation and design optimization of a high efficiency three-level Active Neutral Point Clamped (ANPC) inverter topology using hybrid Si/SiC switches. It uses a modulation strategy that produces a cluster of low frequency switches commutating at fundamental line frequency (realized with Si IGBTs) and high frequency switches commutating at carrier frequency (realized with hybrid Si/SiC switches) to facilitate a tradeoff between the inverter efficiency and cost. A generalized Si/SiC current rating ratio optimization algorithm is presented for the hybrid Si/SiC switches based on the power loss profile of ANPC inverter. This algorithm determines the optimal current rating ratio between the Si IGBT and SiC MOSFET for the hybrid Si/SiC switches based on the inverter operating specification and Si/SiC gate control technique to achieve the best tradeoff between cost, loss and reliability. The performance of the proposed ANPC inverter system is investigated and compared with other similar ANPC inverter systems. The proposed ANPC inverter system achieves higher efficiency compared to an all Si IGBT based ANPC inverter system, all SiC MOSFET based ANPC inverter system, and other ANPC inverter systems consisting mixed Si IGBT and SiC MOSFET devices. On the other hand, the semiconductor device cost of the proposed ANPC inverter system is much lower than an all SiC MOSFET based ANPC inverter system and the mixed Si IGBT and SiC MOSFET based ANPC inverter systems while it is on par with an all Si IGBT based ANPC inverter system.