Optimised switching of a SiC MOSFET in a VSI using the body diode and additional Schottky barrier diode

In this paper the switching behaviour of SiC MOSFETs is regarded with respect to the influence of the free-wheeling diode. A double pulse test was performed using two silicon carbide Schottky barrier diodes (SBD) of different rated currents and the intrinsic body diode of a silicon carbide MOSFET. The switching losses of these three combinations are analysed to find the best combination of MOSFET and antiparallel diode for the application in a voltage source inverter (VSI). The body diode was found to dissipate not negligible switching losses. The effect of a silicon carbide Schottky barrier diode in high current SiC power modules is shown. Calculating the power capability, it is shown that the MOSFET inverter without SBD has the higher power density.