Research On Rotor Bar Breaking And Bearing Fault Diagnosis Of Asynchronous Motor Based On Stator Current

As a widely used industrial equipment,asynchronous motor is a necessary component in modern production.Once the motor fails,it will not only damage motor body,but also affect the entire production system.Therefore,research on the fault diagnosis method of asynchronous motor is of great significance.This paper analyzes the fault type distribution of asynchronous motors and compares the commonly used fault diagnosis methods.For two main faults of asynchronous motors,i.e.rotor broken bars and bearing faults,the corresponding fault features are extracted with stator current characteristic analysis method based on simulation models and actual motor operating data.The fault diagnosis method proposed in this paper is then validated by using these features.The main work completed in this paper is as follows:(1)Analyze the basic structure and operating principle of asynchronous motors.And further analyze faults that happen most frequently and their causes.Focus on analyzing the failure mechanism of rotor broken bars and bearings,and also deeply study the detection mechanism of corresponding failures.(2)Analyze signal processing methods in different domains,including Fourier transform,Hilbert transform and continuous wavelet transform.The rotor operation mechanism is used to construct a function to approximately replace the broken bar fault.The aforementioned processing method is used for detection and verification.Based on this,a subsequent motor fault processing method is established.(3)Combining mathematical model with motor operation equation,a corresponding simulation model is established in MATLAB.By changing the corresponding parameter values,the rotor broken bar fault of asynchronous motor can be simulated.Then,the obtained time-domain waveform is subjected to a windowed fast Fourier transform to obtain a corresponding spectrum diagram.Whether a component(1+2s)f representing the characteristic frequency of rotor broken bar fault appears in the spectrum diagram indicates the accuracy of the model and algorithm.(4)Investigate bearing failures of asynchronous motors.It can be known from other related work that the frequency amplitude of the current characteristic component corresponding to the bearing failure is small,and it is easily affected by harmonics and noise of the power system.Therefore,a new diagnostic method is proposed combining empirical mode decomposition(EEMD)with envelope analysis.The main process of this method is to use EEMD to split the signal into a limited number of eigenmode components and residuals,and then perform an envelope analysis on the obtained components to demodulate the corresponding characteristic frequency.In order to prove the actual performance of this method,the collected signals of actual bearing and simulation signals are analyzed in this paper.The experimental results show that this method can well identify the bearing failure of asynchronous motor.