Safe integration of depletion mode SiC VJFET power modules into a commercial motor drive

This paper addresses the replacement of enhancement mode Si IGBTs with depletion mode SiC vertical junction field effect transistors (VJFETs) in a commercial motor drive in current production. A Yaskawa A1000 CIMR-AU4A0088FAA motor drive was analyzed and found to have reliability and safety features that can be exploited to introduce normally on SiC transistors with no loss in safety or reliability as compared to the baseline configuration using silicon IGBT power modules. It is found that by utilizing the components and basic architecture of the original drive that are intended to ensure single-point-of-failure reliability with IGBTs, the SiC JFETs can be safely integrated. As a result, a significant efficiency increase of 1 to 2 percentage points over the same motor drive with IGBT modules was measured. In terms of the inverter losses, a mean reduction of 36% across the operating range of the drive was observed.