Analysis And Diagnosis Of Three-phase Induction Motor Rotor Faults

The traditional diagnosis method of rotor faults of three-phase induction motors is stator currents spectrum analysis method. However, fault components are susceptible to be flooded. It is necessary to combine a variety of signals to diagnose rotor faults. In this paper, stator currents, radical forces and unbalanced magnetic forces signals are selected to diagnose rotor faults. By analyzing frequency characteristics of these signals when having rotor faults and diagnosing a variety of rotor faults via Finite Element Method(FEM), we can provide some theoretical guides for the rotor fault diagnosis. Details are as follows:First, this paper diagnoses broken rotor bars faults. Methods based on checking fault features in radial force spectrums to diagnose broken rotor bars faults is proposed. Then this paper analyze the severity of fault components when positions of broken rotor bars changes. We find that magnitudes of fault components change periodically with broken rotor bars positions. Then waveforms of stator currents and radial forces are obtained by using FEM. After spectrum analysis, fault features are used to diagnose broken rotor bars faults. Results verify the correctness of the theoretical analysis.Second, this paper diagnoses air-gap eccentricity faults. Methods based on checking fault features in unbalanced magnetic forces spectrums to diagnose air-gap eccentricity fault is proposed. Then waveforms of stator currents, radial forces, and unbalanced magnetic forces are obtained by using FEM. After spectrum analysis, fault features are used to diagnose air-gap eccentricity faults. Results verify the correctness of the theoretical analysis.Finally, this paper studies broken rotor bars mixed with air-gap eccentricity faults. Methods based on checking fault features in unbalanced magnetic force spectrum to diagnose mixed faults is proposed. Then waveforms of unbalanced magnetic forces are obtained by using FEM. After spectrum analysis, fault characteristic values are used to diagnose mixed faults. Results verify the correctness of the theoretical analysis. Finally, we proposed a method which can diagnose a variety of rotor faults.