Research On Fault Feature Of Permanent Magnet Synchronous Motor Based On Magnetic Field Detection

Permanent magnet synchronous motor(PMSM)has been widely used in the fields of energy,transportation and aerospace because of its high efficiency,high power density,low vibration noise and high reliability.With the increasing power of PMSM,the security and reliability of PMSM become more and more important.In order to ensure safe operation of the PMSM,it is very important to diagnose the common faults of the motor in real time.And how to extract the corresponding fault features in time is the key problem of PMSM fault diagnosis.As the basic part of the project “Research on electric and demagnetization faults diagnosis method in permanent magnet synchronous motor based on stator electromagnetic”(51477015),which is supported by the National Natural Science Foundation of China,this thesis will research how to extract the fault features.In this thesis,common faults of PMSM(inter-turn short circuit fault,rotor demagnetization fault and rotor eccentricity fault)are studied.Using the finite element method to analysis the variations of stator teeth magnetic field of PMSM when faults occur.Then,according to the corresponding fault features,the fault property,degree and position of PMSM can be diagnosed in real time.Firstly,the finite element model of PMSM is established.The control system of the motor is built,and the co-simulation platform is constructed.Then,through the detecting coils added on the teeth of stator,the change information of the motor internal magnetic field can be obtained.The method of processing induced voltage of the detecting coil is obtained by theoretical analysis and mathematical derivation.Finally,the finite element models of inter-turn short-circuit fault,demagnetization fault and eccentricity fault are established respectively.The eigenvalues of the three types of faults are compared and analyzed.And,the validity of the proposed method is verified by the analysis results.The results show that when the inter-turn short-circuit fault occurs,the singular value of the fault location will raise with the increase of the fault degree.The sensitivity of judging the degree of inter-turn short-circuit fault can be improved by high frequency components associated with the carrier frequency of the controller.When the demagnetization fault occurs,the radar map of the fault eigenvalues appears to be circular,and the radius of the circle increases approximately linearly with the increase of fault degree.When the eccentricity fault occurs,the radar map of the fault eigenvalues appears to be in the shape of gourd,and the size of radar map will become bigger with the increase of fault degree.The radar map of the dynamic eccentricity fault rotates with time,while the radar map of static eccentricity fault dose not rotate with time.The above results show that the research method of fault features in this thesis can distinguish the common faults of PMSM,and to a certain extent,the degree and location of the fault can be reflected.The method lays a theoretical foundation for the fault diagnosis of PMSM.