A TDF Model in Induction Machines for Loose Bearing Diagnosis by Neutral Voltage

The bearing wear and looseness are significant failures in induction machines. For accurate recognition of the bearing faults, a new comprehensive modeling and analysis of induction machines with three degrees of freedom along with an effective method for loose bearing signature are presented in this article. For these purposes, the electromagnetic radial force and rotating torques are determined and applied to Euler-Lagrange equations of an induction machine. Besides, to better identify the defective loose bearings, the spectral analysis of neutral voltage is utilized. Comparing the experimental results with the outcome of the numerical analysis validates the proposed model. The results show that the spectral analysis of the neutral voltage detects mechanical looseness with higher precision than the conventional techniques such as mechanical vibrations and stator currents.