Research On Fault Diagnosis Of Asynchronous Motor Based On Motor Current Signature Analysis

Asynchronous motor as a power equipment plays a very important role in the industrial production,squirrel cage asynchronous motor is the most widely used asynchronous motor.During the operation process of the equipment,the failure of the asynchronous motor will threaten the smooth progress of production activities,even the huge economic losses and casualties.In this paper,the fault diagnosis method of squirrel cage induction motor based on stator current signal analysis is studied,the main research work is as follows:Firstly,the structure and operating principle of asynchronous motor are discussed,the development status of asynchronous motor fault diagnosis technology and the commonly used fault diagnosis method are introduced,the mechanism of several common faults is analyzed,such as rotor bar fault,fault and fault.It provides the basis for fault diagnosis of asynchronous motor.Secondly,the mathematical model of asynchronous motor is established.Through the mathematical model of the output of the stator current signal spectrum analysis and envelope analysis found that there will be a characteristic frequency component in the stator current signal that is related to the double slip and power frequency when more than one rotor bar breaks.However,the characteristic frequency component is not easily found when the single rotor bar breaks.To effectively extract the characteristics of the rotor bar fault fault from the stator current signal,an analysis method based on the frequency slice wavelet transform is proposed to extract the fault time-frequency characteristic.The stator frequency signal of asynchronous motor is decomposed by frequency slicing wavelet transform to obtain the time-frequency characteristic of broken bar fault,This method overcomes the shortcomings of traditional frequency domain analysis methods that can not be found in minor fault condition.The simulation experiments and asynchronous motor test bench test results show that the stator current signal will appear amplitude modulation phenomenon when the rotor bar fault occurs,The amplitude modulation phenomenon is more significant with the increase of the number of broken bars and the amplitude modulation frequency is twice the slip rate and the power frequency product,The fault feature of the bar fault is represented by the valve-shaped waveform with the interval of the power frequency as the center in the time-frequency diagram.The experiment system of asynchronous motor fault diagnosis is built,and the motor condition monitoring and fault diagnosis software is developed,It can realize the asynchronous motor real-time signal acquisition and fault diagnosis.While the signal data stored in the Access database,it also can be achieved on the historical data query and fault diagnosis.The validity of the fault diagnosis method is verified by the experimental system in this article.