Dynamic calibration: How to properly estimate junction temperature in SiC MOSFETs subject to body diode voltage shift

Abstract:
The body diode voltage VSD of SiC MOSFETs is a well-known temperature-sensitive electrical parameter (TSEP) to estimate the junction temperature of the chip. Nonetheless, some SiC MOSFETs exhibit an unstable VSD that shifts over time, regardless of their temperature. This article characterizes this reversible voltage shift and outlines the challenges that arise when using the body diode as a TSEP. A new VSD (T, t )-method that relies on dynamic calibration to account for this effect is introduced. Furthermore, a simplified compensation method is presented. The different methods are compared to the standard one by calculating the cooling curve of a device.