Conducted EMI Comparison of Two Electric Machines used in Electrified Transportation

Abstract

This paper examines the conducted electromagnetic interference (EMI) generated by a two-level voltage-source inverter (VSI) that performs active rectification. The paper evaluates two test configurations. The first configuration uses an aerospace wound-field synchronous (WF) machine as the active-rectifier’s power source. For the second configuration, the active rectifier’s power source is an automotive interior permanent magnet (IPM) machine. Each machine provides a nominal 115Vac at a power level of 40kW, and the active rectifier converts the ac-voltage to a nominal 270Vdc. The research evaluates each active rectifier configuration against MIL-STD-461G and DO-160G, and in both cases, the active rectifier produces higher EMI when the IPM machine is the power source. Finally, this study designs and analyzes four second-order common-mode filters and four fourth-order common-mode filters. The result is that each machine has two filters to pass MIL-STD-461G and two filters to comply with DO-160G. As expected, the IPM-based active rectification systems needs a larger common-mode inductance under every testing condition. It requires a second-order filter inductance that is 12-times higher than the WF-based active rectifier system. The second-order filter’s inductance is 80-times larger for DO-160G compliance.