Rotor Mechanics Behavior Characteristics for Diagnosis SAGE Fault in PMSG with Load Change

Static air gap eccentricity (SAGE) is a common mechanical fault in permanent magnet synchronous generators (PMSG). Currently, eccentricity detection is mainly based on inductance, back electromotive force, stator vibration, electromagnetic torque, etc. Differently from the other research, this paper focuses on the unbalanced magnetic pull (UMP) characteristic and mechanical response on the rotor to find the approach for diagnosing SAEG and reveal dangerous positions of the rotor, also taking into account load changes. A 5Kw PMSG with 10 pole pairs is employed as the investigation object of the simulations for verification. It is shown that the UMP points to the minimum air gap position and has a positive linear correlation between the UMP and SAGE degree. Moreover, the outer surface and inner surface edges of the rotor core are in the most dangerous positions. Such conclusions can be treated as evidence of the effectiveness of the SAGE diagnosis method and failure prevention of the rotor.