Study On Broken Bar Fault Diagnosis Of Asynchronous Motor Based On Current And Vibration

As a source of power for the operation of the machine,if the motor malfunctions during operation,the fault not only damages the motor itself,but also affects the entire production system,causing huge economic losses and bad social impact.Motor broken bar is a common fault of the motor.If the motor continues to be used after breaking the bar,the stress of other conductors will increase.This will further damage the entire cage structure of the motor.In severe cases,even a "broom" phenomenon may occur,and other parts of the motor may be damaged.,Intensify the damage of the entire motor.Therefore,this paper mainly investigates the vibration characteristics and current characteristics of motor broken-bar faults under different working conditions.Based on this,the fault feature extraction and intelligent diagnosis of motor faults based on Ensemble empirical mode decomposition are realized.Firstly,this paper analyzes the characteristics of the current and vibration signal of the broken bar fault of the asynchronous AC motor.It is proposed that the characteristic frequency of the motor broken bar fault has a large difference from the amplitude of the fundamental wave frequency and it easily causes the frequency of the fault feature to be submerged by the fundamental frequency or noise.Fault Diagnosis Method of Motor Broken Bar Based on Ensemble Empirical Mode Decomposition(EEMD)and Hilbert Envelope Demodulation.EEMD decomposition is equivalent to band-pass filtering,which can reduce noise interference.Using Hilbert envelope demodulation analysis,the fault feature frequency can be uniformly converted to fault modulation frequency,highlighting fault feature information.For example,after the vibration signal of the motor broken bar is analyzed by Hilbert envelope demodulation,mechanical vibration and electromagnetic vibration are superimposed,which enhances the modulation characteristics of the fault characteristics of the vibration signal.At the same time,in order to further study the current and torque response under the action of the broken motor fault,this paper establishes the simulation model of the asynchronous motor through the Ansoft/Mxawell finite element simulation software,and uses this model to simulate the different physical characteristics of the motor under the condition of three broken strips.And verify the effectiveness of the method of EEMD decomposition combined with Hilbert envelope demodulation in the current diagnosis of broken bar motor.On this basis,the current characteristics of different number of broken wires of the motor were simulated.The simulation results show that the more severe the broken bar of the motor,the more obvious the modulation phenomenon of the current signal.Secondly,experimental simulations were conducted on a rotor comprehensive test platform and the following six experimental conditions were set: normal motor no-load,no-load motor broken bar,normal motor load,motor load broken bar,motor broken bar-load bearing fault,Motor break-motor bearing fault,through the data acquisition system to obtain the motor vibration and current signals under six different conditions,using EEMD decomposition and Hilbert envelope demodulation method for six kinds of motor current and vibration signal,and through the comparison and analysis of the experimental data,the advantages and disadvantages of the motor current and vibration signal to identify the fault of the broken bar under different working conditions are obtained.Finally,the intelligent diagnosis method of the motor broken bar fault is studied.The intelligent diagnosis method combining EEMD decomposition and SVM is used to identify the fault degree of the motor broken bar and the fault type of the motor broken bar.The quad-classifier kernel function parameters were optimized using the grid selection method.By comparing the stability of the frequency band energy characteristics of the vibration signal and the current signal under different working conditions of the motor,it is concluded that the fault diagnosis effect of the motor broken bar based on the vibration signal is better than the current signal.At the same time,a multi-information fusion based on current and vibration is designed to identify the broken bar fault of the motor,and the effective fusion and diagnosis of the current signal and the vibration signal in the intelligent diagnosis of the broken bar fault of the motor are realized...