Online Monitoring of SiC MOSFET Junction Temperature with Full-range and Gate oxide Defect Insensitivity

Abstract:
This paper proposes a method in which the on-state voltage is used as the sampling signal for online junction temperature estimation when the silicon-carbide metal-oxide semiconductor field-effect transistor (SiC MOSFET) operates in the third quadrant and current flows through the body diode. This method eliminates the influence of threshold voltage drift and extends the junction temperature estimation range to more than double that of conventional methods. To implement this method, a high-accuracy voltage sampling circuit is developed, along with a dedicated sampling and pulse width modulation (PWM) control strategy. The effectiveness and precision of the proposed approach are validated experimentally.