ABSTRACT
At present, there are two main motor current detection models for rolling bearing fault detection. One is the radial vibration transmission model which was first proposed by Schoen et al. (1995), who believed that a rotating eccentricity will be generated in the stator when the bearing is under a fault frequency. This eccentricity will lead to periodic variation of the motor induction current. Another is the torque vibration transmissionmodel.This considers that a transient fluctuation of torque will be generated when the ball passes through a pit in the inner and outer rings. Most scholars believe that there is an amplitude modulation relationship between this fluctuation component and power grid frequency. Blodt et al. (2008) further deduced that the periodic variation of torque can also cause the phasemodulation of the stator current, which is named frequency modulation. No matter what kind of model, an additional frequency fbf is generated in the stator current:
where fs is the motor stator power supply frequency, fc is the rolling bearing fault frequency, k = 1, 2, . . ..
