An Investigation of Frequency Response Analysis Method for Junction Temperature Estimation of SiCs Power Device

This paper investigates a new technique for detecting the junction temperature of Silicon Carbide (SiC) MOSFET devices using frequency response analysis. It has been reported that the junction temperature of an unbiased SiC MOSFET can be determined by estimating the frequency response using a network analyser. The presented technique benefits from the temperature dependency of the internal gate impedance of the SiC device. Change in the junction temperature causes a change in the internal gate impedance, and this, in turn, will change the characteristics of the estimated frequency response. However, a network analyser is expensive and thus this paper proposes a modified approach where less expensive equipment is used. The proposed method is using the magnitude of the frequency spectrum rather using reflectometry used by network analysers. A single-chip SiC MOSFET packaged in a TO-247-3 housing is used in this investigation along with a Tektronix AFG3102 for signal sweeping and a PicoScope3206b for data logging and frequency response estimation.