Modeling and Validation of Common-mode Emissions of SiC MOSFET-based Voltage Source Inverter Motor Drive

The high switching frequencies and edge rates enabled by wide-bandgap (WBG) power semiconductors, such as SiC and GaN MOSFETs, promise higher power density without efficiency penalty in grid-compatible variable frequency drive (VFD) systems. A significant challenge to be addressed in WBG-based VFD design is compliance with EMC standards without over-design. Therefore, common-mode (CM) behavior models that are highly accurate in higher frequencies and computationally efficient are needed. This study demonstrates a “gray”-box analytical method for the CM behavior modeling of an unfiltered 150 hp DC-fed three-phase VFD and the hardware validation. The model developed in this study can mathematically model the differential-mode cross-mode coupling effects on the CM equivalent circuit due to electric circuit and magnetic structure asymmetry with an accuracy of up to 30 MHz.