Research On Electrical Fault Diagnosis Of Asynchronous Motor

Asynchronous motor is the core equipment in the field of coalmine,energy,chemical industry,etc.Motor failure often occurs,which will seriously endanger the life safety of field workers.Hence,the detection and diagnosis of asynchronous motor ' s electrical fault have significant value of research.This thesis takes asynchronous motor as the object of research,studying the inter-turn short circuit fault of motor stator as well as the rotor bar breaking fault,completing the following research:(1)Mechanism analysis of common malfunctions of asynchronous motor,modelling of fault characteristics and feature analysis of extraction current.The mathematical model of motor stator winding's inter-turn short circuit fault of induction motor was established to improve the original model in response to the difficulty in fully demonstrating the parametric variations of the inter-turn short circuit fault of motor stator.The simulation of the inter-turn short circuit fault of motor stator was done through Ansys modelling analysis based on the improved mathematical model.Fourier transform was utilised to get the characteristic frequency of the motor during the occurrence of inter-turn short circuit fault of motor stator.The operation of motor was analysed under both normal and fault status through Ansys modelling based on the failure mechanism of motor rotor bar breaking fault.The rotor bar breaking fault which was reflected in the characteristic frequency component of the stator current was extracted to verify the accuracy of theoretical analysis.(2)Further accurate extraction of the fault feature using the method of Variational Mode Decomposition(VMD).The method of Variational Mode Decomposition(VMD)was introduced in response to the occurrence of multiple malfunctions of the fault motor and the issues of nonlinear non-stationary current signal due to the impact of environmental factors.The simulation analysis manifests that VMD decomposition can effectively avoid the two types of modal aliasing and over-decomposition in the case of discontinuous signals,frequencysimilar signals and pulse signals,thus accurately reflecting the characteristics of signal source.This not only effectively reduces the interference of the current power frequency to the fault characteristic frequency but also provides a new reference for the application of current analysis in motor fault diagnosis.(3)On line diagnosis platform of fault motor based on variational mode decompositionUsing LABVIEW to program,combining the variational mode decomposition method with the diagnosis platform,the paper analyzes the stator inter turn short circuit fault motor and the rotor bar break fault motor respectively,and verifies the accuracy of the theory and simulation.The experimental environment simulates the actual working environment of the motor,and the experiment has reference value.