Power Loss Analysis of Medium Voltage Three-Phase Converters using 15 kV/40 A SiC N-IGBT

Abstract

Medium-voltage (MV) silicon carbide (SiC) devices such as the 15-kV SiC N-insulated gate bipolar transistor (IGBT) have better thermal withstanding capability compared with silicon (Si)-based devices. These devices also have lower switching and conduction losses at high switching frequencies and high power levels, respectively. The maximum safe operating junction temperature for the 15-kV SiC IGBT is 175 °C. This enables high power density design of the MV converters using this device. Heat sink with forced air cooling is considered for dissipating the heat generated during converter operation. In this paper, the power loss analysis of three-phase MV converters based on 15-kV/40-A SiC N-IGBT is discussed. The converter thermal analysis is carried out based on the experimental loss data and the continuous heat-run test of the device. It is supported by analytical calculations, PLECS thermal simulations, and FEM simulations in COMSOL Multiphysics software. Hardware prototypes of the converters are developed and the experimental results support the analysis. Experimental results are given for both hard-switched grid-connected converter and soft-switched dual active bridge converter. The paper mainly focuses on the semiconductor losses in the converter.