A Simplified Hard-Switching Loss Model for Fast-Switching Three-Level T-Type SiC Bridge-Legs

Hard-switching losses in three-level T-type (3LTT) bridge-legs cannot be directly estimated from datasheet energy loss curves, which are given for symmetric two-level half-bridge configurations only. The commutations a 3LTT bridge-leg occur between semiconductors with different blocking voltages and/or current ratings, and involve third semiconductor device the switching transition, contributes additional capacitive losses. This paper, therefore, describes simplifed approach to estimate lower bound hard-switching of (note that is applicable other topolgies as well). In view very fast speeds wide-bandgap semiconductors, model neglects voltage/current overlap considers only dominating charge-related contributions (semiconductor output capacitances, body diode reverse-recovery charge), thus requiring minimal information datasheets. A direct experimental verification an 800 V DC-link (1200 650 SiC MOSFETs) operating currents up 25 confirms good accuracy simplified switching-loss model.