Method Of Fault Diagnosis In Induction Motor Based-on The Feature Analysis Of The Current

As a widely used industrial facility,Induction motor is an integral part of the modernization mass production.Once faults occurred,not only damage the induction motor,and even affect the entire production system.Therefore,it's important to study the method of fault diagnosis to induction motor.In this paper,analyzes the distribution of the main fault types and compares the current mainstream fault diagnosis techniques,then according to rotor broken bar fault,stator inter-turn short circuit fault and bearing fault,select the corresponding fault characteristics based on the stator current characteristic analysis,then verifies the method of fault diagnosis for induction motor based on feature analysis in stator current proposed in this paper through the analysis and test of stator current collected in petrochemical induction motors.Combined with slip calculation based on slot harmonic,Nuttall window and triplespectrum-line interpolation correction algorithm and chirp-z transform,select the percentage of?1±2s? ?₁ amplitude to fundamental component amplitude as the fault feature to diagnosis rotor broken bar fault.While the load fluctuates,the edge frequency component of the fundamental frequency spectrum leakage may be coincident with the fault characteristic frequency,which will affect the diagnosis result.When the load fluctuation exceeds the threshold value,the diagnostic method of Hilbert modulus spectrum analysis is adopted to convert the broken bar fault characteristic frequency into 2s?₁ to avoid the adverse effect of load fluctuation.Analysis of the composition of the negative sequence component of stator current in the stator inter-turn short circuit fault,collect and analysis the steady-state current under different working conditions,remove the negative current component caused by the imbalance of the supply voltage and the inherent imbalance of the induction motor,extract of residual negative sequence current component as fault characteristic of the stator inter-turn short circuit fault.The amplitude of characteristic frequency of the bearing fault in the stator current is small,which is easily affected by the harmonics and noise of the power system.According to the statistical properties of autocorrelation function,determine the noise or signal-dominated IMF component node,combines soft threshold noise reduction,highlighted the bearing fault characteristic frequency.in spectrum of reconstructed stator current.