Voltage division investigation of series short‐circuit fault on SiC MOSFETs and Si IGBTs

Abstract

Abstract In power electronic systems, when a power device turns on by mistake, there would be at least two devices in the short‐circuit (SC) current loop, forming series short‐circuit (SSC) fault. In this paper, the dynamic characteristics of SiC MOSFETs, Si IGBTs in SSC are investigated based on the half‐bridge circuit. The effect laws of load current and junction temperature to voltage division in SSC are discussed. Taking a three‐level (3‐L) active neutral point clamped (ANPC) topology based on hybrid utilization of Si IGBT and SiC MOSFET as the research object, the SSC performance is investigated. The theoretical and experimental results show that, in the process of SSC, the voltage division features of SiC MOSFETs and Si IGBTs are different and highly sensitive to circuit parameters. When both SiC MOSFET and Si IGBT are in the SC current loop, the device with a lower saturation current level limits the short circuit current and bears most of the dc‐bus voltage. Moreover, in the Si/SiC hybrid 3‐L ANPC topology, if the saturation current of selected SiC MOSFETs is higher than that of Si IGBTs, the SC withstanding level of SiC MOSFETs could be improved, thereby reducing the SC protection circuit requirements.