| Permanent magnet synchronous motor(PMSM)has been widely used in the field of new energy as a representative of high-efficiency and energy-saving motor.Therefore,this paper designs a IPMSM for electric vehicles,and analyzes the radial electromagnetic force and modal frequency with the motor as the research object.Through the above analysis results,the influence of motor structure and current harmonic on electromagnetic vibration is studied in detail,The main research contents are as follows:Firstly,according to the performance index and design requirements of the motor,the main dimensions of the motor are determined,the rotor magnetic circuit structure is selected,the size of the permanent magnet is estimated,then the winding type and the wire parameters are selected,the permanent magnet and silicon steel sheet materials are selected to complete the preliminary design of the motor,and the rationality of the electromagnetic design is verified by the finite element simulation,it lays a foundation for the follow-up study of motor vibration characteristics.Secondly,according to the theory of radial electromagnetic force,the main components of electromagnetic force wave under no-load and load operation of the motor are summarized by using the analytical formula.The derived conclusion is consistent with the spatial order and frequency distribution of radial electromagnetic force of the 8-pole 48 slot built-in permanent magnet synchronous motor calculated by the finite element simulation.The modal frequency of stator core is analyzed by finite element simulation,and the possibility of resonance is discussed.In addition,the influence of winding,casing and end cover on the natural frequency of stator structure is analyzed.Then,the influence of the structure of the motor on the electromagnetic vibration is studied,and the influence of the pole arc angle,the width of the stator slot and the eccentricity of the rotor on the radial electromagnetic force is analyzed in detail.Then,a method based on the magnetic barrier of the rotor is introduced to reduce the air gap magnetic density harmonic,so as to reduce the magnitude of the 8th and 16 th order radial electromagnetic force of the motor.At the same time,three parameters of the yoke thickness,the tooth height and the tooth width of the stator are analyzed.The results show that the wide and shallow stator slot shape is helpful to improve the modal frequency of each order.Finally,the influence of current harmonics on electromagnetic vibration is studied.the MTPA control model of the motor is established in the MATLAB/Simulink simulation environment,the current harmonics under vector control of the motor are extracted,and the expression of radial electromagnetic force considering current harmonics is derived.Through the combination of analytical method and finite element method,the existence of harmonic current can increase the amplitude of high-frequency electromagnetic force.Therefore,a voltage error compensation method based on α-? two-phase static coordinate system is adopted.This method can obviously reduce the current harmonic under frequency conversion drive,and achieve the purpose of reducing electromagnetic vibration. |
PDF Full Text Request