Research On Fault Diagnosis Of Permanent Magnet Synchronous Motorbased On Stator Tooth Flux

Permanent magnet synchronous machine(PMSM)is wildly used in the important areas such as aeronautics,astronautics,wind power generation,transportation and military.Its accidents not only cause great losses but also may cause safety accidents.Sensitive and accurate on-line fault diagnosis is the key to detect the fault at early stage,and ensure the safe and stable operation of PMSM and the entire drive system.Aiming at inter-turn fault,demagnetization fault and eccentricity fault of PMSM,the influence of the fault on stator tooth fluxes is analyzed,quantitative relationship between the fault parameters and the tooth fluxes is revealed.For each kind of fault,the fault indicators and diagnosis method are proposed based on the tooth fluxes,and a multiple fault diagnosis device is developed.Simulations and experiments show that the proposed method can identify the fault parameters such as location,range and severity.The proposed method is sensitive and accurate;it can diagnose the early faults effctivly.The study is helpful for achieve more comprehensive and accurate on-line monitoring of PMSM and has important theoretical significance and practical value for promoting the development of key equipment manufacturing in China.The main contents of the thesis are as follows:(1)On the basis of the traditional fault mathematical model,the tooth flux with different fault is deduced and analyzed,the results are verified by co-simulation.A real-time measuring device of stator tooth flux based on search coils is designed and developed.The above work lays the foundation for fault diagnosis study based on stator tooth flux.(2)The method of fault features extracting and fault parameters estimating of inter-turn fault is studied.A diagnosis method based on tooth flux high order harmonics and fundamental phasor are proposed.Compared with the similar methods,the proposed method is more sensitive and accurate,and can effectively detect faults at early stage,and accurately reveal the fault location,short turns and short resistance.Experiments verify the effectiveness of the proposed method.(3)The relationship between local demagnetization fault and the time-frequency characteristics of stator teeth flux is studied.A local demagnetization diagnosis method based on tooth flux amplitude derivative and side frequency component is proposed.The proposed method can detect the local demagnetization,identify the number of fault poles,and demagnetize severity.Compared with the similar methods,the proposed method can diagnose the fault severity more accurately,and is independent from the operating conditions of the PMSM.Experiments verify the effectiveness of the proposed method.(4)The relationship of eccentricity ratio and the space-time distribution of tooth flux is studied.An eccentricity fault diagnosis method based on the change ratio of tooth flux reciprocal are proposed.The proposed method can not only detect the eccentricity,but also identify its type,estimate the direction and magnitude of eccentricity ratio.The proposed method can reveal the actual distance and orientation of the eccentricity,compared with the similar methods,it is more accurate,and is independent from the operating conditions of the PMSM.Experiments verify the effectiveness of the proposed method.(5)By using co-simulation,the interference of mixed faults to various diagnosis methods is analyzed,and the extraction method of fault indicators is improved for mixed faults.Mixed fault diagnosis method is composed of the improved single diagnosis methods,which can diagnose inter-turn fault,demagnetization,eccentricity and mixed fault.Experiments and co-simulations verify the effectiveness of the mixed fault diagnosis method.