Research On Typical Fault Diagnosis Method Of Permanent Magnet Synchronous Machine

With the continuous evolution of world politics,economy and environmental protection,the world energy structure has undergone profound changes,and the production and consumption of electric energy has become increasingly important to ensure the safety of nation’s energy production and consumption.The electric machine is one of the core equipment on the power production side and the consumer side.The Prognostics Health Management(PHM)technology of the machine helps the maintenance personnel to detect and eliminate the early faults of the machine in time,and avoid greater equipment loss and casualties due to the deterioration of the fault.Therefore,It has important and realistic significance.In recent years,due to its excellent performance,Permanent Magnet Synchronous Machine(PMSM)have been widely used in the electromechanical systems of high-tech weapons such as remote weapon station,warship propulsion system,and fighter ElectroMechanical Actuator(EMA).Compared with asynchronous machines and DC machines,PMSM have many advantages such as higher power density,better controllability,lower noise,lower vibration,smaller size and lighter weight.However,interturn short-circuit and demagnetization fault have been threatening the operation of PMSM.A lot of research has been done for the interturn short-circuit fault and demagnetization fault of PMSM,but they are limited by the different structures of PMSM and the difficulty of early fault detection,the detection and diagnosis are in the ascendant.This paper takes the surface-mounted PMSM as the research object,and the fault characteristics and fault diagnosis methods of permanent magnet demagnetization fault and inter-turn short-circuit fault of PMSM which is excited by AC power supply are studied.The research contents include the following aspects:(1)The mathematical model of the surface-mounted PMSM in the three-phase static coordinate system is established,and use the mathematical model of PMSM in the synchronous rotating coordinate system.Based on the above model,through the basic modules in Simulink,a simulation model of a PMSM is established and verified.(2)According to Maxwell’s equations and the structural characteristics of PMSM with concentrated windings with fractional slots,the electromagnetic field finite element software is used to establish a PMSM model excited by AC power,and the Finite Element Model(FEM)is analyzed under transient field conditions.(3)For interturn short-circuit faults,the simulation model and FEM model of PMSM are used to generate fault signals of different severity,and the change trend of various signals after the fault is analyzed.To solve the problem that it is difficult to find fault characteristics of early interturn short-circuit fault,the fault indicators in the stator current spectrum and inverse electromotive force,Support Vector Machine(SVM)are used.(4)Aiming at the magnet demagnetization fault of surface-mounted PMSM,the mechanism of permanent magnet demagnetization fault was analyzed,and two sorts of simulation schemes of demagnetization fault were established.The variation characteristics of each physical quantity of machine after the occurrence of uniform demagnetization and partial demagnetization were analyzed.(5)Early partial demagnetization fault in the stator phase current spectrum is not easy to detect,collection and PMSM in different degree of demagnetization under the running condition of stator phase current,the Sum of Square of the Phase Current(SSPC)method is used to eliminate power frequency,highlight the fault characteristic frequency,so as to improve the partial demagnetization fault detection ability of PMSM.All in all,this research topic for PMSM,interturn short-circuit fault and demagnetization fault characteristics are analyzed.Two fault diagnosis methods based on current spectrum feature are proposed.which provide a useful exploration of fault diagnosis methods for typical PMSM faults..