Research on the current feature of induction motor bearing fault based on phase modulation

This paper researches the features of stator current affected by the vibration characteristic which is caused by bearing faults. Based on the phase modulation theory proposed by Blödt, the form of the stator current is theoretically derived in accordance with the Bessel function and the characteristics of the stator current´s sideband frequencies are studied. In order to determine the amplitude characteristics of the sideband frequencies, the test rig which can simulate single-point defect via generating torque vibration is established. The obtained results validate the idea that the amplitude characteristics of the sideband frequencies accord with Bessel function of the first kind. During the experimental verification, the amplitude characteristics of sideband frequencies become obvious and the number of sideband frequencies which can be identified increases when the electrical supply frequency is lower. The results conform to the theoretical features of stator current. Therefore, it is conducive to determine the severity of the fault.