Real-Time Junction Temperature Sensing for Silicon Carbide MOSFET With Different Gate Drive Topologies and Different Operating Conditions

The switching transient properties from the switching power semiconductor gate side are sensitive to the device's junction temperature (T-j). Real-time T-j sensing methods based on gate drive switching transient properties have been investigated on silicon MOSFET and silicon IGBT, with a conventional push-pull-type gate drive, under fixed dc-bus voltage. In this paper, this method is applied to silicon-carbide (SiC) MOSFET. The T-j sensingmethods are evaluated with different types of gate drive topologies. By implementing the SiC MOSFETs into an H-bridge inverter, the effect of dc-bus voltage for the T-j sensing method is investigated. Different "gate drive-semiconductor" dynamic models are built, including gate drive output power stage, gate drive parasitics, SiC MOSFET intrinsic parameters, and PCB parasitics. Experimental results are compared with circuit LTSpice model simulation. The device vertical temperature contours are evaluated. Suitable circuitry for T-j sensitivity extraction is provided.