Multi-Domain Design Optimization of dv/dt Filter for SiC-Based Three-Phase Inverters in High-Frequency Motor-Drive Applications

Abstract

High slew rate of the line voltage (dv/dt) has been a concern for power inverters based on the emerging wide bandgap (WBG) devices, such as Silicon Carbide (SiC) MOSFETs. Particularly, for SiC based power inverters feeding electric machines with long cables, there is more stringent requirement for low dv/dt, due to the concerns of insulation stress on the stator windings in electric machines. Compared to the conventional lower-voltage electric transportation applications (e.g., 270V dc), higher dc bus voltage of 500 V ∼ 600 V can reduce the systematic copper losses, hence improve the power density of power converters. However, high dc bus voltage further increases the dv/dt stress in the converter ac line voltages. Driven by using SiC inverters in high-frequency motor-drive applications with 500V dc bus, this paper presents a multi-domain design approach for dv/dt filters that comprehensively considers the constraints in electrical, magnetic, and thermal domains. Experimental results based on a 75 kW SiC inverter are provided to verify the efficacy of this design approach.