Electrified EHL line contact with dielectric breakdown of lubricant -- a numerical model

TL;DR

This paper introduces a numerical model to analyze electrical discharge phenomena at EHL line contacts in electric motor bearings, aiding in understanding and mitigating electrically induced bearing damage in electric vehicles.

Contribution

A novel numerical model for discharge-induced current density and voltage drop at EHL contacts, emphasizing the role of surface roughness and enabling future damage mitigation strategies.

Findings

Current density and voltage drop can be efficiently computed using the conjugate gradient method.

Surface roughness significantly influences electrical discharge characteristics.

The model provides insights into electrical behavior at inaccessible lubrication interfaces.

Abstract

With the rapid growth of the electric vehicles with drive systems with higher voltages, power outputs, frequencies, and speeds, mitigating electrically induced bearing damage (EIBD) in electric motors has become critical. In this study, a novel numerical model characterizing discharge-induced current density and voltage drop at the elastohydrodynamic lubrication line contact interface is presented. The current density and voltage drop constitute a linear complimentarily problem, which is efficiently solved using the conjugate gradient method. This paper sheds light on electrical characteristics at the inaccessible lubrication interface during discharge, highlighting the significance of roughness radius of curvature on current density. This numerical model lays the groundwork for future research on mitigating or even permanently solving EIBD problems in electric motor bearings.