Research on vibration characteristics of permanent magnet synchronous motor rotor parallel eccentricity and bearing inner ring radial misalignment coupling fault

Permanent magnet synchronous motors are being used more frequently because of their efficiency, power density, and precision. However, there has been insufficient research on the effects of radial misalignment of bearings and rotor eccentric coupling faults on the vibration characteristics of these systems. This paper develops a finite element model of the rolling bearing-rotor system of a permanent magnet synchronous motor and derives models for the nonlinear unbalanced magnetic pull and the nonlinear bearing restoring force. Research indicates that the occurrence of a coupling fault leads to the emergence of high-frequency components within the system. Additionally, a combined frequency component associated with the bearing variable compliance frequency is also observed. As the failure rate escalates, there is a notable increase in the bearing restoring force, which significantly enhances the support stiffness of the rotor. This increase effectively suppresses the rotor’s vibration in the normal direction and diminishes the amplitude of the rotation frequency in the spectral diagram. However, as the failure rate increases, the combined frequency components become increasingly complex, and the amplitude rises significantly. Additionally, the impact of the bearing’s radial initial clearance on the vibration characteristics of the faulty system was investigated. This study reports on experimental research, showing results that are consistent with the theoretical computations, thus confirming the validity of the theoretical model. The outcomes of this investigation provide a conceptual basis for identifying and diagnosing rotor eccentric faults in permanent magnet synchronous motors.