Bearing voltages and resulting currents in electric machines driven by PWM converters with fast switching and high dv/dt can cause premature bearing failures. With the transition from conventional Si devices to wide bandgap (WBG) devices and increase in switching frequency, bearing voltages and currents become more significant and need to be addressed from the early design stage. This paper proposes to use coupled field-circuit electromagnetic finite element analysis (FEA) to model bearing voltage and current in electric machines, which takes into account the influence of distributed winding conductors and frequency-dependent winding RL parameters. The three known bearing current types are explained and modeled in a unified way by using the proposed approach with simple calculation examples. Potential bearing current issues in axial-flux machines, and possibilities of computation time reduction, are also discussed.

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Conference Proceeding

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Notes/Citation Information

Published in Proceedings, IEEE Energy Conversion Congress and Exposition.

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The document available for download is the authors’ manuscript version accepted for publication. The final published version is copyrighted by IEEE and available as: Han, P., Zhang, Y., Kesgin, M. G., Heins, G., Patterson, D., Thiele, M., and Ionel, D.M., “On the Modeling of Bearing Voltage and Current in PWM Converter-fed Electric Machines Using Electromagnetic Finite Element Analysis,” Proceedings, IEEE Energy Conversion Congress and Exposition (ECCE), Vancouver, Canada, pp.1-5, Oct 2021.

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Funding Information

The support of Regal Beloit Corporation, University of Kentucky, the L. Stanley Pigman Endowment, and of Ansys Inc., is gratefully acknowledeged.