Fault Diagnosis Of Permanent Magnet Synchronous Machine With High Frequency Signal Injection

The sustainable development of contemporary society is faced with the double constraints of energy and environment."Carbon Peak" and "Carbon Neutrality" have become a basic national policy in our country.In terms of energy production,wind power generation,as one of the most mature renewable energy utilization technologies,has drawn more and more attention.In addition,the low-carbon and environmentally friendly forms of energy consumption such as electric vehicles are also being promoted.The permanent magnet synchronous machine has become the mainstream choice in the applications as wind power generation and electric vehicles for higher power density and reliability requirements.Therefore,the fault diagnosis of permanent magnet synchronous machine is studied in this thesis,where the high-frequency signal injection technology is employed for the detection of inter-turn short circuit fault,local demagnetization fault and high-resistance fault.In this thesis,theoretical analysis,simulation and experimental verification are combined to seek the fault diagnosis method with high resolution and good accuracy,which provides a technical basis for further improving the reliability and economic benefit for the applications of permanent magnet synchronous machine.The main work of this thesis is as follows:(1)The traditional high frequency signal injection methods,including rotating high frequency voltage injection,pulsating high frequency voltage injection,rotating high frequency current injection,are analyzed in detail.And an active vector rotating high frequency voltage injection method is proposed and analyzed.All the analysis lays the technical foundation for the fault diagnosis methods.(2)The mechanism and fault characteristics of inter-turn short circuit in permanent magnet synchronous machine is analyzed,and the diagnosis methods based on negative-sequence high frequency current response,partial winding high frequency current injection,zero-sequence high frequency voltage response are proposed respectively.Among them,the method based on negative-sequence high frequency current response does not require additional sensors and the diagnostic performance is not affected by the motor operating conditions;The method based on partial winding high frequency current injection can achieve accurate diagnosis even when multi faults occur in different phase windings simultaneously;The method based on zero-sequence high frequency voltage response processes higher detection resolution than the traditional method,and the detection resolution can be further improved by employing the active vector rotating high frequency voltage injection.(3)The local demagnetization fault of a permanent magnet synchronous machine and the law of convex polarity change of the machine inductance are studied.Based on this,a local demagnetization fault detection method using rotating high frequency voltage injection is proposed,where the local demagnetization fault can be accurately detected by extracting specific high frequency component in zero-sequence voltage.The relevant conclusions are verified by simulation and experiment.(4)The discrimination method of early failures including inter-turn short circuit fault,local demagnetization fault and high-resistance fault is proposed,where high frequency current injection and zero-sequence voltage measurement are employed.The component in the zero-sequence voltage related to inter-turn short circuit fault or high-resistance fault has the same frequency as the injection frequency.The amplitude of inter-turn short circuit fault related component increases with the injection frequency,while the amplitude of high-resistance fault related component remains unchanged.The local demagnetization fault related component has a different frequency from that of the inter-turn short circuit fault and high-resistance fault.Thus,inter-turn short circuit fault,local demagnetization fault and high-resistance fault can be discriminated employing the dual-frequency high frequency current injection.