Comparative assessment of 3.3kV/400A SiC MOSFET and Si IGBT power modules

In this paper, a comparative evaluation between a commercial 3.3 kV/400 A Si-IGBT and a 3.3 kV/400 A SiC MOSFET power module in half-bridge configuration is presented. With a constant current of 250 A, a lower forward voltage (VDS) drop of 1.6 V is obtained for SiC MOSFET at 300 K compared to Si IGBT. At 400 A, the difference is reduced to 1.3 V. SiC MOSFET offers an on-state resistance of 8.7 mΩ, and blocking voltage of 3.5 kV at 300 K. Compared to Si-IGBT, a significant lower leakage current for the SiC MOSFET is obtained with varying temperature from 300 K to 400 K. SiC MOSFET offers 7.5 times lower switching losses compared to Si-IGBTs for a supply voltage of 2000 V at 300 K. The switching losses of the SiC MOSFET are not affected by the temperature. Total energy loss increases (3.5 times) linearly with variation of the gate resistance from 6 Ω to 27 Ω. The capability of the SiC MOSFET to withstand short-circuit (SC) events under hard switch fault condition is also investigated. The SiC MOSFET power modules survived short circuit tests performed at a DC-link voltage of 1.5 kV and a pulse duration of 3 μs with a measured short-circuit energy of 6.4 J. The SiC power module failed when the pulse duration was increased to 4 μs, where a short-circuit energy of 9.1 J was obtained. The cause of the failure is the thermal runaway leading to a drain-source short.