Bearing voltages and corresponding currents in electric machines driven by pulse width modulation (PWM) converters with fast switching and high dv/dt can cause premature bearing failures. This paper evaluates the bearing voltage reduction by using insulated shafts and bearings. An equivalent circuit representation of electric machines taking into account high-frequency effects is developed to show the production mechanism of bearing voltage, based on which simulations are performed with detailed finite element models for transient and simplified equivalent circuit for steady-state analysis. The steady-state equivalent circuit is then calibrated, by combined numerical calculations and experimental measurements, and used to predict the bearing voltage for various scenarios, proving the effectiveness of using insulated shaft and bearings in reducing the steady-state bearing voltage.

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Conference Proceeding

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Notes/Citation Information

Published in 2020 IEEE Energy Conversion Congress and Exposition (ECCE).

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The document available for download is the authors’ manuscript accepted for publication. The final published version is copyrighted by IEEE and available as: P. Han, G. Heins, D. Patterson, M. Thiele, and D.M. Ionel, “Evaluation of bearing voltage reduction in electric machines by using insulated shaft and bearings,” 2020 IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI, Oct. 11-15, 2020, pp. 5584-5589, doi: 10.1109/ECCE44975.2020.9235474.

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Funding Information

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