Design consideration of GaN HEMT for a three-phase motor inverter and the impact of the reverse conduction on the losses of inverters

The impact of reverse conduction of a depletion mode (D Mode) GaN HEMT was studied experimentally by comparing the losses of two half bridge configurations one with and one without an antiparallel SiC diodes. The results show that with a dead time of 200ns, the reverse conduction of the GaN increases the losses by an insignificant 0.15% at 100kHz switching frequency, and hence that the relatively high cost SiC anti parallel diode is superfluous. Based on these results, a three-phase motor drive inverter with six parallel GaN switches per each leg, without parallel diodes, was designed, constructed and tested experimentally.