Online Junction Temperature Monitoring for Discrete SiC MOSFET Based on On-state Voltage at High Temperature

Abstract

Junction temperature monitoring is crucial for condition monitoring and thermal management of power semiconductor devices. In this paper, the online monitoring of junction temperature for discrete SiC MOSFETs is achieved by simultaneous measurements of their on-state voltage and current. A dedicated calibration circuit that decouples switching and conduction losses is used to obtain a look-up table for the junction temperature. According to the test results, under the operating condition with current of 50 A and temperature of $175^{\circ} C$, a single pulse test of $10 \mu$ can cause a temperature rise of 8-9 $^{\circ} C$, due to the self-heating effect of the discrete SiC MOSFETs. This temperature rise of DUT during the calibration test is compensated by the Foster network thermal model of the device afterwards.