Dynamic Behavior of Permanent Magnet Synchronous Motor Rotor Radial Eccentricity

Abstract With the rapid advancement of new energy vehicles, permanent magnet synchronous motors are being increasingly utilized. Among the various faults that can occur, rotor eccentricity fault in permanent magnet synchronous motors is a common issue. This study utilizes the finite element method and the Timoshenko beam element theory to develop a dynamic model of the rotor. It also establishes models for the hybrid eccentric unbalanced magnetic pull (UMP) and the bearing restoring force. It was found that the rotation frequency component in the spectrum response diagram under fault conditions appears a 'peak' phenomenon in the subcritical speed region. By analyzing the dynamic characteristics of the system when the permanent magnet synchronous motor rotor experiences radial eccentricity fault, it is observed that the UMP leads to an increase in the bearing contact load. The system's spectrum response is primarily influenced by the rotor rotation frequency and frequency multiplication components due to the coupling of UMP and bearing restoring force. This paper investigates the influence of permanent magnet residual magnetism on the vibration characteristics associated with rotor eccentric faults. The findings indicate that the magnitude of the residual magnetism is positively correlated with the amplitude of frequency doubling. Additionally, this study includes experimental research that corroborates the accuracy of the theoretical model. The conclusions presented in this article offer a theoretical foundation for the detection and diagnosis of radial eccentricity faults in permanent magnet synchronous motor rotors.