Research On Current Characteristics Of Bearing Outer Raceway Defect Of Induction Motor Bearings

Due to its simple structure,good operation performance,cheap price and wide applicability,the induction motor is widely used in residential life,industrial production and national defense and military affairs.Bearing as an important part of induction motor,the probability of defect is also very high,it is easy to lead to the induction motor operation failure.It is of great significance to study the characteristics of induction motor bearing defect to realize the on-line monitoring of bearing defect and ensure the normal operation of the motor.In this paper,based on the periodic pulse model of bearing defect proposed by Blodt,it was found that the analysis based on this model could only see the frequency doubling of the characteristic frequency,which was too idealistic.Combined with the dynamic simulation analysis,the improved torque fluctuation model is derived,and the stator current expression of bearing outer raceway defect is derived.The theoretical analysis shows that the double frequency of the characteristic frequency and the triple frequency can be used as auxiliary features to detect the bearing defect.On this basis,this paper uses the square envelope spectrum to preprocess the current signal,so as to reduce the influence of the fundamental wave on the fault characteristic frequency.Using TKEO energy operator to demodulate stator current,the characteristic frequency and its multiplication frequency are directly demodulated,which makes the characteristic frequency more prominent and improves the identification of the characteristic.To solve the problem of weak features in current signals,this paper adopts the method of voltage adjustment and speed regulation to highlight the proportion of sliding friction,and this method can also make the characteristic frequency away from the power frequency,so as to facilitate identification.The motor simulation model was established based on matlab.For the simulation data,the method of square envelope spectrum and TKEO energy operator was used for comparative analysis,and the simulation results verified the feasibility of the method.An experimental platform for bearing defect of induction motor was built in the laboratory environment to collect stator current data according to different power frequency.Through power spectrum analysis of stator current signal,square envelope spectrum analysis and TKEO energy operator demodulation analysis,it is verified that the method is more effective than traditional power spectrum analysis,and is suitable for bearing defect detection of induction motor.