Locomotive Traction Motor Bearing Fault Detection Via The Analysis Of The Stator Current

The traction motor is one of the most important units in a locomotive, it will directly affects traffic safety, due to poor working conditions,load changes frequently, the large space constraints, power and so on, traction motor prone to failure,so we carried on the traction motor state detection and fault diagnosis.In this paper, the stator current is ana-lyzed by means of wavelet packet decomposition to detect the faults of traction motor. The contributions and conclusions are made as follows:The stator current in search of current harmonics directly related to new rotating flux components, which are caused by faults in the motor. Motor-current-signature analysis has been successfully used in induction machines to detect electrical faults, such as broken rotor bars, abnormal levels of air-gap eccentricity, and shorted turns in stator windings. However, bearing faults are the most frequent faults in electric motors according to the IEEE motor reliability study. The models for bearing fault detection are presented. An analytical model for the influence of rolling-element bearing faults on induction motor stator current is described. 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.According to the stator current signal with a non-stationary characteristics, we analyse and compare the stator current signal processing strengths and weaknesses of the wavelet transform and wavelet packet transform, and how to select the appropriate wavelet function. The results show the wavelet packet decomposition provides a better treatment of non-stationary stator current.An induction motor test rig was setup. Experimental tests with realistic bearing damage were conducted by measuring vibration, rotating speed and stator current. The obtained results by wavelet packet analysis to the motor stator current validate the proposed diagnostic approach. The proposed method was effectively applied to the operation test of locomotive, and the fault of a traction motor bearing was detected successfully.Based on the investigations mentioned above, a locomotive traction motor bearing fault diagnostic method via the analysis of the stator current is presented. And the fault of a traction motor bearing was detected successfully.