Study On Bearing Fault Diagnosis Of Induction Motor With Variable Frequency Drive System

Fault diagnosis in bearings is the technical prerequisite for safe production andavoiding accidents. Rolling bearing is one of the most important parts of motor in normaloperation. Rolling bearing is one of the most easily damaged parts of motor componentssystems.The incipient fault characteristic of the induction motor is usually very weak. Forspeed regulation and energy saving requirements, the induction motor is driven byfrequency converter. The soaring harmonic component in converter and the noiseproduced by peripheral equipment make it more difficult for the incipient fault detection.Aiming at the bearing fault of the induction motor, this dissertation focuses on incipientfault characteristic extraction and detection in heavy noise.This paper first analyzes the principle and vibration characteristic for typical fault ofbearing, then explaining the principle of analysising and diagnosing bearing faultsinformation in the inverter.A filter used to extract weak signal in the inverter is presentedto extract weak fault signal based on spectral kurtosis. Via short-time Fourier transform tothe vibration signals,the estimation of the spectral kurtosis is given. According to thespectral kurtosis, a filter controlled by signal-to-noise ratio is constructed automatically toremove the noises and harmonic components.Then the incipient bearing faultcharacteristic information could be very obvious by means of the envelope analysis，Then analysis the feature of vibration signal under the inverter, Through the simulation ofthe vibration signal,shows the feasibility of kurtosis filter method,finally through thetest,analysis the vibration signals under with inverter and without inverter,analysis thevibration signals of different carrier frequencies and different speed,realizes the faultdiagnosis by kurtosis filter method.