Temperature estimation of sic power devices using high frequency chirp signals

Abstract

Silicon carbide devices have become increasingly popular in electric vehicles, predominantly due to their fast-switching speeds, which allow for the construction of smaller power converters. Temperature sensitive electrical parameters (TSEPs) can be used to determine the junction temperature, just like silicon-based power switches. This paper presents a new technique to estimate the junction temperature of a single-chip silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET). During off-state operation, high-frequency chirp signals below the resonance frequency of the gate-source impedance are injected into the gate of a discrete SiC device. The gatesource voltage frequency response is captured and then processed using the fast Fourier transform. The data is then accumulated and displayed over the chirp frequency spectrum. Results show a linear relationship between the processed gate-source voltage and the junction temperature. The effectiveness of the proposed TSEPs is demonstrated in a laboratory scenario, where chirp signals are injected in a stand-alone biased discrete SiC module, and in an in-field scenario, where the TSEP concept is applied to a MOSFET operating in a DC/DC converter.