Precise and Fast Real-Time Measurement of Junction Temperature in SiC Power MOSFETs

Real-time measurement of junction temperature is critical for high reliability operation of power devices. The process of SiC MOSFETs turn-on is very short. The rising edge of the peak gate current may be less than 10ns, and the existing peak gate current measuring circuit cannot match the high-frequency characteristic of SiC MOSFETs. This paper presents a precise and fast circuit to estimate the junction temperature of SiC MOSFETs, which adds a current riser and the rectifier diode is replaced by a matching high-speed triode. The designed circuit can determine the peak gate current in real-time, regardless of the converter's actual operation, and eliminate the need for supplemental control signals. Empirical evaluation is conducted using double-pulse tests, demonstrating that the SiC MOSFET's peak gate current, exhibits a linear relationship with the junction temperature, with a sensitivity of approximately -0.107 mA/degrees C. The circuit's temperature estimation accuracy is further corroborated with an IR (infrared radiation) camera. Additional validation is provided by the Boost converter, confirming the circuit's functionality even without interference from the converter's main circuit.