A Study of Motor Bearing Fault Diagnosis using Modulation Signal Bispectrum Analysis of Motor Current Signals

Abstract

Failure of induction motors are a large concern due to its influence over industrial production. Motor current signature analysis (MCSA) is common practice in industry to find motor faults. This paper presents a new approach to detection and diagnosis of motor bearing faults based on induction motor stator current analysis. Tests were performed with three bearing conditions: baseline, outer race fault and inner race fault. Because the signals associated with faults produce small modulations to supply component and high nose levels, a modulation signal bispectrum (MSB) is used in this paper to detect and diagnose different motor bearing defects. The results show that bearing faults can induced a detestable amplitude increases at its characteristic frequencies. MSB peaks show a clear difference at these frequencies whereas conventional power spectrum provides change evidences only at some of the frequencies. This shows that MSB has a better and reliable performance in extract small changes from the faulty bearing for fault detection and diagnosis. In addition, the study also show that current signals from motors with variable frequency drive controller have too much noise and it is unlikely to discriminate the small bearing fault component.

A Sparse Modulation Signal Bispectrum Analysis Method for Rolling Element Bearing Diagnosis

“…In 2004, a new AM detector and its normalized form are proposed and defined [12]; Gu et al named this method as the modulation signal bispectrum (MSB) analysis and achieved fault diagnosis of downstream mechanical equipment using electrical motor current signal based on MSB in 2011 [13]. After that, their team continued to deeply study, analyze, and improve on the MSB method and also achieved a series of results [14][15][16][17][18].…”

Detection and diagnosis of compound faults in induction motors using electric signals from variable speed drives

“…Because of this, it is not adequate to describe amplitude modulation (AM) signals such as motor current signals [20].…”

“…To improve the performance of the conventional bispectrum in characterising the motor current signals, a new variant of the conventional bispectrum, named as a MSB is examined [10,13,20,21] …”

The identification of shaft current induced defects on rolling bearings in wind turbine generators

“…According to the references [10][11][12][13][14][15], MSB is an effective demodulation technique and demonstrated to be able to detect bearing faults under heavy noise influences, Based on Fourier transform   Xf of a vibration signal x , MSB is defined as the following equation.…”

“…Gu et al named this method as the Modulation Signal Bispectrum (MSB) analysis and achieved fault diagnosis of downstream mechanical equipment using electrical motor current signals in 2011 [10]. After that, their team continues to deeply study and analyse the method to achieve a series of achievements [11][12][13][14][15].…”