Squirrel Cage Induction Motor Condition Monitoring And Fault Diagnosis Methods Of Research

Motor as the power supply equipment and driving equipment most widely usedin all kinds of industries. In the view of electric energy production， more than90%of the current application of electric energy is generated by synchronous generator; Inthe view of electric energy consumption， more than70%of electric energy isconsumed or converted into mechanical energy. Due to most of equipment operationand work are driven by all kinds of motor presently， so motor has been widely usedin industrial production and all aspects of people’s life.For long-term operation, some structure and components will be graduallydegraded, thus slight fault will develop into serious fault, which even leads to seriousproduction accidents and causes the significant loss of life and property. Therefore,there is significantly social and economic benefits to do the research on how to detectthe signal character of incipient faults or abnormal operation in squirrel-cageinduction motor as soon as possible and according to the results of the signal analysisand processing to judge fault type, and take pertinent measures. The risk of machinefailing can be remarkably reduced if normal service conditions can be arranged inadvance. In other words, one may avoid very costly expensive downtime of plant byproper time scheduling of machine replacement or repair if warning of impedingfailure can be obtained in advance.Extract fault characteristic from fault signals is the key of motor state monitoringand fault diagnosis. Methods based on signal analysis and processing are mainly usedto extract fault character signal. Due to the fact that most of fault signals arenon-stationary and nonlinear properties, it is essential to choose appropriate signal-processing methods that are suitable for extracting fault character from nonlinear andnon-stationary signals.This thesis regards squirrel-cage induction motor as the research object, researchdifferent kinds of traditional fault signal analysis and processing method on inter-turnshort circuit and bar broken at home and broad,summarize the different characteristics and insufficient, analyze the mechanism of motor rotor bar broken and inter-turn shortcircuit, study the distribution of magnetic force in condition of failure. On the basis offault mechanism, extract the fault characteristic value. Using HHT transform methodtake various fault simulation under transient and steady state two operating mode.Using HHT transform to fault feature localization, reach the purpose of statemonitoring and provide a basis for fault diagnosis. Simulated the harmonic and SFMsignals in the workbench LABVIEW, application HHT analysis module simulatedmotor fault signals, the results showed that HHT analysis module can extract faultsignal characteristics accurately,which has successfully applied in the fault diagnosissignal example of the rotor fault, and in the operation speed, precision, interfacedesign have been improved.The main contents of this thesis as follows:(1) Analysis the reasons causing trouble of asynchronous motor in the transientand steady state;(2) Analysis the principle of rotor fault diagnosis based on stator currentmonitoring method;(3) Extract corresponding characteristic feature for each type of fault;(4) Analysis the influence of harmonic of fault signal;(5) Using HHT algorithm under LABVIEW platform to judge the fault types, andputs forward the corresponding control strategy.