20 kW, 50 kHz SiC Power Converter for High Speed Switched Reluctance Machine

Abstract

This paper reports design and testing of an SiC devices based three phase asymmetric H-bridge converter capable of switching at 50 kHz and intended to drive high-speed switched reluctance machines of speeds up-to 50,000 rpm. The power converter architecture is presented. Selection of SiC MOSFETs and diodes for the given power rating and specifications are discussed. Other subsystems of the converter are also described. Test results are presented for the asymmetric H-bridge converter at 800 V dc bus voltage and 50 A of load current. The MOSFET and diode losses are calculated for the given test condition. The respective junction temperatures and the heat-sink temperature are also estimated. Thermal image is presented for validation of estimated heat-sink temperature. The power converter is used to operate two high-speed SRM prototypes.