Power Loss, System Efficiency, and Leakage Current Comparison Between Si IGBT VFD and SiC FET VFD With Various Filtering Options

SiC devices are gaining acceptance in the motor drive industry. This paper compares the power loss and efficiency between two options that can be used with SiC-based variable frequency drives (VFDs). In the first option, the SiC VFD is equipped with an output sine-wave filter with carrier frequency at 50 kHz. A dv/dt filter is used for the second option with the carrier frequency reduced to 8 kHz. Both options are compared with a standard Si insulated-gate bipolar transistor (IGBT) VFD operating at a carrier frequency of 8 kHz with no output filter. The focus of this paper is to present different filtering options for SiC VFDs. The dv/dt filter is designed to meet the same specification as that of the standard Si IGBT VFD with no output filter, so as to present a fair comparison between a standard Si IGBT VFD and the next-generation SiC VFD. Results using a 460-V 11-kW system show that the SiC VFD with an output sine-wave filter has a lower efficiency compared with SiC VFD with a dv/dt filter. Influence of the various filtering options on leakage current in the motor drive system has also been studied, and the results are presented in this paper.