Models for Bearing Damage Detection in Induction Motors Using Stator Current Monitoring

TLDR

Bearing faults are a major cause of drive failures and can be detected by vibration monitoring of characteristic frequencies, prompting interest in using stator current monitoring for fault detection. The study proposes a new analytical model to describe how rolling‑element bearing faults affect induction motor stator current. The model is based on two fault‑induced effects—specific radial rotor movement and load torque variations—and is validated through experimental tests measuring vibration, torque, and stator current. The theoretical expressions for stator current frequency content derived from the model were confirmed by spectral analysis of experimental data from artificial and realistic bearing damage.

Abstract

This paper describes a new analytical model for the influence of rolling-element bearing faults on induction motor stator current. Bearing problems are one major cause for drive failures. Their detection is possible by vibration monitoring of characteristic bearing frequencies. As it is possible to detect other machine faults by monitoring the stator current, a great interest exists in applying the same method for bearing fault detection. After a presentation of the existing fault model, a new detailed approach is proposed. It is based on the following two effects of a bearing fault: 1. the introduction of a particular radial rotor movement and 2. load torque variations caused by the bearing fault. The theoretical study results in new expressions for the stator current frequency content. Experimental tests with artificial and realistic bearing damage were conducted by measuring vibration, torque, and stator current. The obtained results by spectral analysis of the measured quantities validate the proposed theoretical approach.