In-circuit Shoot-through-based Characterization of SiC MOSFET TSEP Curves for Junction Temperature Estimation

Junction temperature estimation for power electronics devices is gaining more importance every day. It enables predictive maintenance and full exploitation of the power handling capability of both traditional and wide band-gap devices. The on-state voltage is known to be a good Temperature-Sensitive Electrical Parameter (TSEP), especially for MOSFETs. The main issue in its use is the need to characterize the voltage-temperature-current relationship on a per-device basis (calibration) in a controlled environment, which increases the cost for the final application.This paper presents a novel automatic calibration procedure. It builds on the innovative controlled shoot-through technique, introduced by the authors. This allows to precisely control the self-heating power of the switch and let the current flow through the device in a controlled way, even in the absence of load, provided that a half-bridge circuit is used. A specific algorithm is presented to build the voltage-temperature characteristic curve directly in-circuit and without any load connected at the bridge output. This novel technique is compared to the traditional one, relying on device characterization in a thermal chamber.