Signal Processing Technique for Detecting Chip Temperature of SiC MOSFET Devices using High Frequency Signal Injection Method

This paper presents a new technique to detect the junction temperature of Silicon Carbide (SiC) MOSFET devices. The process of detection is based on injecting a high frequency/low amplitude sweep signal into the gate lead of a SiC device during its OFF-state period. A frequency response analysis is carried out to determine the variation in the impedance which is a function of temperature change. The technique is applied first in simulation by the development of a small-signal model of a single-chip SiC device packaged in a TO-247-3 housing. The frequency response is then compared with experimental data obtained from a high-frequency network analyser (Agilent Keysight E5071B). Results demonstrate that simulation and experimental data are comparable thus, on one hand, it validates the proposed OFF state small signal model, and on the other hand, it confirms the effectiveness of the proposed method for detecting the junction temperature of SiC MOSFET devices.