Switching Transient-Based Junction Temperature Estimation of SiC MOSFETs With Aging Compensation

This article puts forward a novel online method to measure the junction temperature ($T_{j}$) of silicon carbide (SiC) mosfets. In this method, the voltage spikes in the common source stray inductance are captured to obtain the turn-on and turn-off switching transients of SiC mosfets. The switching transients contain useful information pertaining to the temperature and are used to extract the junction temperature. By measuring both turn-on and turn-off switching transients, the technique effectively addresses the impact of aging on the online junction temperature measurement procedure. The proposed method enables the measurement of junction temperature without high-bandwidth current sensors. In order to improve precision, this approach converts the measured voltage spikes into digital signals with specific pulse width, which can be measured by high-resolution capture module in the microcontroller with an error of less than 1 $^{\circ }$C. Importantly, the proposed circuit has minimal impact on the normal operation of the converter and can be integrated into the gate driver integrated circuits (ICs). The effectiveness of this method is validated through experiments conducted on a double-pulse test setup and buck converter. The results confirm the practicality and viability of this approach.