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.
Digital Object Identifier (DOI)
The support of Regal Beloit Corporation, University of Kentucky, the L. Stanley Pigman Endowment, and ANSYS Inc., is gratefully acknowledged.
Han, Peng; Heins, Greg; Patterson, Dean; Theile, Mark; and Ionel, Dan M., "Evaluation of Bearing Voltage Reduction in Electric Machines by Using Insulated Shaft and Bearings" (2020). Power and Energy Institute of Kentucky Faculty Publications. 55.