Analytical Estimation of Turn on Switching Loss of SiC mosfet and Schottky Diode Pair From Datasheet Parameters

Abstract

Estimation of switching loss at the early stages of design is essential for determination of switching frequency and selection of power devices. Analytical estimation similar to gate charge method results in fastest and easiest computation when compared with simulation or double pulse test based experimental approach. This paper presents an analytical estimation method of turn on switching loss of a SiC mosfet and SiC Schottky barrier diode (SBD) pair from datasheet parameters and using values of common source and dc bus inductances. Turn on losses are considered as they dominate the total switching loss. The presented method models the quadratic nature of the transfer characteristics and results in better estimation of current rise time when compared with the linear approximation used in the literature. During voltage fall, the non-linear nature of the parasitic capacitances of both the switch and the diode are considered. The simulation and experimental results confirm the accuracy of the presented method over a range of operating conditions for two 1.2-kV discrete SiC mosfet and SBD pairs of different current ratings.