EMI measurement on electric vehicle drive inverters using a passive motor impedance network

As a result of the power train electrification in electric and hybrid vehicles the electromagnetic compatibility of these vehicles is comprehensively affected. Especially the power electronic components operated at battery voltages of around 400V produce broadband EMI inside the vehicle. To prove compliance with the normative requirements considering the vehicles inner EMC, EMI measurements on component level are used. As testing a drive inverter requires an electric motor as load which has to be mechanically loaded by another inverter driven system possibly affecting the measurement, the load torque has to be generated outside the shielded chamber. As the mechanical connection of the two drives through the chamber's wall has to be shielded, it is quite difficult to realize. Thus in this work a passive load is developed, modeling the impedance behavior of an existing motor. Thus no bushing and no setup for load torque generation has to be used for drive inverters test setup according to CISPR 25. This circuit is realized to model the load for drive inverters typically used in electric vehicles. Finally the results of the EMI measurements at the passive network and at the modeled drive are compared.