Gear Transmission Fault Diagnosis Based on the Bispectrum Analysis of Induction Motor Current Signatures

Abstract

Abstract：Motor current signal analysis has been an effective way for many years to monitor electrical machines.However, little research work has been reported in using this technique for monitoring their downstream equipment due to difficulties in extracting weak fault signals in a noisy measured current signal. This paper investigates the characteristics of electrical current signals measured from an induction motor for monitoring faults from a downstream gear transmission system by a novel modulation signal (MS) bispectrum method. Both analytic analysis and experimental study are conducted based on a motor drive system and have found that the increase of bispectral peaks can be the basis of mechanical fault diagnosis. Particularly, a fault on a gear will causes a larger increase of the bispectral peak at both the gear shaft frequency and accompany with a smaller increase in the relating shaft frequency. However, a shaft misalignment only leads to a bispectrum peak increase at the shaft bifrequency along.

Gear Wear Process Monitoring Using a Sideband Estimator Based on Modulation Signal Bispectrum

“…Bispectrum analysis is a useful signal processing tool that has shown significant benefits over traditional spectral analyses due to its unique properties of nonlinear system identification, Gaussian noise elimination, and phase information retention [14][15][16][17][18][19][20][21]. Conventional bispectrum (CB) was applied to vibration signals for the detection of different degrees of tooth breakage of a two-stage helical gearbox and tooth crack [15].…”

“…Conventional bispectrum (CB) was applied to vibration signals for the detection of different degrees of tooth breakage of a two-stage helical gearbox and tooth crack [15]. Chen et al [16] introduced MSB, which is a significant improvement of the CB in that it enhanced CB to apply the modulation signal efficiently. The results showed reliable fault diagnosis and revealed that random noise can be suppressed effectively, being much better than that of the power spectrum (PS) and CB for diagnosing different seeded faults, such as tooth breakage and shaft misalignment [16].…”

Diagnosis of combination faults in a planetary gearbox using a modulation signal bispectrum based sideband estimator

“…Whereas through the second path, the vibration signal follows a longer path, from its origin to the shaft firstly, then from the shaft go through the sun gear, planet gear and ring gear, after that from the ring gear to the gearbox casing, and finally to the sensor. Therefore, the vibration signal will be amplitude modulated by both sun gear rotating frequency and carrier rotating frequency as shown in (14).…”

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].…”