A 1200-V, 600-A silicon carbide (SiC) JFET half-bridge module has been developed for drop-in replacement of a 600-V, 600-A IGBT intelligent power module (IPM). Advances in the development of SiC field effect transistors have resulted in reliable high yield devices that can be paralleled and packaged to produce high-voltage and high-current power modules not only competitive with existing IGBT technology but the modules have expanded capabilities. A SiC vertical junction field effect transistor VJFET has been produced with the properties of lower conduction loss, zero tail current, higher thermal conductivity, and higher power density when compared to a similarly rated silicon IGBT or any practical SiC MOSFETs previously reported.
Three prototype SiC JFET half-bridge modules with gate drivers have been successfully integrated into a three-phase 30-kW (continuous), 100-kW (intermittent) AC synchronous motor drive designed to control a traction motor in an electric vehicle. The commercially available motor drive, originally designed for silicon IGBT IPMs, was evaluated in conjunction with a permanent-magnet brushless DC motor on a dynamometer. Normal operation of the motor drive using field-oriented control and pulse-width modulation at 12.5 kHz was observed. Characterization of the SiC power module in the forward bias safe operating area demonstrated up to a 50% reduction in forward conduction losses as compared to the silicon IGBT IPM it replaces. The lack of a body diode in the SiC vertical-channel JFET is one major advantage of this switch topology allowing SiC Schottky barrier diodes to be used as the anti-parallel rectifier without undesirable conduction through a MOSFET body diode. Modules have been constructed using both depletion mode and enhancement mode 1200-V VJFET switches with industry leading low specific on resistance (≺4 mΩ-cm₂) produced by SemiSouth Laboratories.