Research On Fault Analysis Of AC Machine Based On Parameter Identification

The induction motor is used widely, and its operating condition is variable, the fault of which always occured, but by this time the problems of fault diagnosis for induction motor hasn't be solved yet. When the motor faults such as rotor broken bar or stator turn-to-turn fault, the electromagnetic field and parameter of induction motor would change. This thesis studies the parametric variation and transient behavior after the induction motor faults.The electrical parameters is important to kinds of performance for induction motor, the compute method of electric resistance and reactance for induction motor is analyzed, and the motor is computed with RMxprt module of Ansoft company, input the parameter such as running conditions, material characteristics, winding arrangement, the slot-type size and so on, then the performance parameters of induction motor can be get.The method conjoint of Finite Element Method (FEM) and Energy Perturbation Method (EPM) is used to study the variable laws of parameters of induction motor when at fault condition. The gross magnetic energy of induction motor is computed by finite element method. And the self-inductance of motor's phase winding can be computed by energy perturbation method, computed at the two fault conditions including rotor broken bar and stator turn-to-turn fault. It is found that the influence of rotor broken bar to self-inductance is small, but with the severity of stator turn-to-turn fault is deepen, the self-inductance of motor is smaller. According which the motor can be estimated whether is fault or not.Based on the various parameter estimation methods for induction motor are studied, the mathematic model for which is established, some parameters for steady-state T-mode equivalent circuit is identified, the parameters of induction motor is identified at normal condition and at fault condition, some laws is found is that certain parameters would change.By simulating and experimental research to the main faults of the motor, man-made faults such as one-bar broken and two-bar broken of rotor, the transient behavior of the motor running in fault status and normal status is studied, such as starting current, electromagnetic torque, residual voltage after AC dump and so on. And by comparing and analysing on the experimental result, It is found that when motor has faults, the electromagnetic torque would fluctuate, the residual voltage after AC dump would appearance harmonic component and so on, and the feature becomes more obvious when the fault is heavier.