An online junction temperature detection circuit for SiC MOSFETs considering threshold voltage drift compensation

Temperature is the main factor affecting the reliability of SiC MOSFETs. Therefore, real-time monitoring technology for junction temperature has become a prerequisite for implementing thermal management strategies. Based on the temperature sensitive electrical parameter method, this paper first determines the temperature dependence of the threshold voltage Vth. Secondly, a SiC MOSFETs junction temperature detection circuit based on threshold voltage is constructed using a T flip-flop. Furthermore, based on this circuit, the junction temperature detection of SiC MOSFETs is achieved. This method has a simple circuit structure, does not require intrusion into the device interior, and can be measured online. Then, an inverter experimental platform is built, and the junction temperature detection performance of the proposed method is tested both offline and online. The experimental results showed that the proposed method has good sensitivity and linearity(-5 mV/degrees C), and the error is less than 3 degrees C. Finally, this paper further proposes a threshold voltage drift compensation strategy flow for the junction temperature model to correct the detection error caused by aging.