Research On Temperature-Dependent Overcurrent Protection Schemes For Sic Mosfets

The maximum continuous drain current of SiC MOSFETs varies with the junction temperature, which is closely related to load and ambient temperature. The traditional constant threshold overcurrent protection based on hardware or software cannot adjust the protection threshold according to the junction temperature, resulting in the failure of protection. The relationships among the on-state resistance, the maximum current, the maximum power loss, the junction temperature and the case temperature are analyzed first and then a novel temperature-dependent overcurrent protection scheme is proposed in this paper, which is based on the case temperature of SiC MOSFETs. The threshold of overcurrent protection can be adjusted in real time and it enables the maximum current operation of SiC MOSFETs, which means the utilization rate of power devices is enhanced. The proposed schemes is applied on a single-phase inverter and the experiments show that the scheme can effectively widen the safe operation area of SiC MOSFETs.