Mechanism of Shaft End-to-End Voltage Generation by Asymmetry in an Inverter-Driven Motor.

This paper deals with the shaft end-to-end voltage resulting from asymmetric stray capacitances in an inverter-driven motor. The origin of the voltage can be any of the following: a ground leakage current, dielectric breakdown in the bearings, and asymmetric stray capacitances on the stator windings. The third origin seems to be related to the differential-mode current, but the details of the relationship have not been clarified. In this study, differential-mode tests are carried out on an ungrounded motor rated at 400 V and 15 kW, and shaft end-to-end voltage generation by the asymmetric stray capacitances is theoretically discussed. Finally, a winding model is presented for the purpose of understanding the mechanism responsible for the shaft end-to-end voltage. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(1): 48-56, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22415 [ABSTRACT FROM AUTHOR]