SiC and GaN power transistors switching energy evaluation in hard and soft switching conditions

Abstract

SiC and GaN power transistors switching energy are compared in this paper. In order to compare switching energy Esw of the same power rating device, a theoretical analysis is given to compare SiC device conduction loss and switching losses change when device maximal blocking voltage reduces by half. After that, Esw of a 650V GaN-HEMT is measured in hard switching condition and is compared with that of a 1200V SiC-MOSFET and a 650V SiC-MOSFET with the same current rating, in which it is shown that Esw of a GaN-HEMT is smaller than a 1200V SiC-MOSFET, which is smaller than 650V SiC-MOSFET. Following by that, in order to reduce device turn-ON switching energy, a zero voltage switching circuit is used to evaluate all the devices. Device output capacitance stored energy Eoss are measured and turn-OFF switching losses are obtained by subtracting Eoss, which shows that GaN-HEMT is sill better than SiC device in terms of switching losses and 1200V SiC-MOSFET has smaller switching losses than 650V SiC-MOSFET.