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

Summary 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