On the application of extended grounded slot electrodes to reduce non-circulating bearing currents

Abstract

Power-electronic-Inverterconverter-induced motor bearing currents are a widespread problem in the field of electrical drives. Parasitic capacitances between the electrical machines parts provide a path for leakage currents, which finally harm the metallic ball bearings. Remembering that end-windings have a significant contribution in building up stray capacitances, a countermeasure affecting both the lamination stack and end winding overhang areas is wantedneeded. The Thiscurrent paper focuses on a countermeasure against the non-circulating bearing currents in the cluster of solutions at the motor side. The eElectrostatic shielding approach, which is a known principle to reduce capacitive couplings, is applied in electrical machines every now and then. In the currentis work, the principle of slot-embedded grounded electrodes is extended to cover also the end-windings. and tThus the electrodes provide a better shaft voltage mitigating effect compared to the case where electrodes are applying applied only inof the approach to the lamination stack area only. The feasibility and effectiveness of such a countermeasure are investigated. Different options in terms of scaling of both the machine size and diameter of the inserted grounded electrodes were analyzed and corresponding conclusions were pointed out.