Robustness of Grounded-Electrode Approach to Mitigate Bearing Currents in Electric Machines with Semi-Closed Slots

Abstract

Electric motors are integral to diverse industrial applications, yet their reliability is hampered by bearing currents-a parasitic phenomenon causing excess wear and damage to the machine's bearings. This paper addresses the pressing issue in modern electric machines, particularly those powered by frequency converters, focusing on non-circulating bearing currents and the Grounded-Electrode Approach (GEA) as a countermeasure. While the approach is promising, a critical aspect remains unexplored-the influence of electrode misplacement, especially in machines with semi-closed slots. Extending previous research, this study numerically assesses the impact of misplacement on bearing currents reduction, crucial for practical implementation. The GEA involves inserting thin grounded wires into stator slot clearance, acting as electrostatic shields. This paper extends the investigation, numerically assessing the impact of grounded electrode's misplacement on bearing currents reduction, specifically addressing machines with semi-closed slots. Scenarios with different misplacements are examined, offering valuable insights for optimizing this mitigation strategy. Understanding the nuances of electrode positioning enhances the ongoing dialogue on reliable electric machine design, with a focus on the effective mitigation of bearing currents.