Research On The Mechanism And Features Of Induction Motor Bearing Faults

Three-phase induction motors play an important role in the field of industrial productions because of their simple construction and high reliability. In spite of that, once the motor fails, it may cause financial losses due to the unplanned downtimes of production process. Hence, in order to realize online fault diagnosis, researching on the mechanism and features of induction motor bearing faults is of great significance.Based on the phase modulation theory proposed by Blodt, the mechanism of bearing fault is studied. The stator current is theoretically derived with considering the effect of torque vibration harmonics. And the amplitude features of stator current eigenfrequencies are researched combined with software simulation. The energy of stator current eigenfrequencies is small due to the fact that the peak amplitude of torque vibration caused by bearing fault is small, which is not conducive to researching the amplitude features. Thus, the bearing fault simulation test rig is established.This thesis accomplishes the theoretical derivation about the effect of bearing fault on stator current, gives the amplitude expression of stator current eigenfrequencies and explains the effect of torque vibration harmonics on the amplitude of eigenfrequencies. The effect of torque vibration harmonics on the amplitude of stator current eigenfrequencies is verified after analyzing different signals, and stator current amplitude features are summarized.Based on the results of software simulation hardware simulation and experimental verification, the derived amplitude expression of stator current eigenfrequencies is verified. The amplitude features of eigenfrequencies become obvious and the number of eigenfrequencies which can be identified increases when the electrical supply frequency is lower. This conclusion is conducive to determine the severity of the fault. In addition, the amplitude features of stator current eigenfrequencies are not only related to the fault severity but also related to the size of the fault zone.