Eccentricity faults diagnosis based on motor stray magnetic field signature analysis

In this paper, the stray magnetic field of induction motor under static eccentricity, dynamic eccentricity and mixed eccentricity faults is studied, and its frequency signatures are derived, where the theoretical analysis is based on the harmonic magnetomotive force and air gap permeance of induction motor with squirrel cage rotor. Motor stray magnetic field signature analysis has the advantages of simple measurement, low cost and noninvasive. The dynamic eccentricity and mixed eccentricity faults can be accurately identified by the combining of motor current and stray magnetic field signature analysis. First, the finite element model of induction motor is developed and the stator current and stray magnetic field can be simulated. Then, eccentricity fault diagnosis experimental platform is established, and hall sensor and magnetoresistive sensor are used to measure the stator current and stray magnetic field of motor. Finally, the simulation and experimental data are analyzed and the results prove the validity of the theoretical analysis, the method of motor stray magnetic field signature analysis can effectively diagnose the eccentricity faults.