Study On Topological Structure Of Primary Permanent Magnet Linear Motor With Magnetic Barrier Coupling

The rail transit system is driven by linear motor,which has significant advantages in climbing ability,traction performance,vibration and noise.Linear induction motor has been used in the drive system of long-distance rail transit,but it`s efficiency and power factor need to be improved.In this paper,a new structure motor-Magnetic barrier coupling primary permanent magnet single side excitation linear motor(MBCPPMUELM),is proposed,which has the advantages of linear induction motor,high power factor and efficiency.Firstly,the significance of the research and the new structure motor are put forward.In view of the current development status of rail transit system,this paper analyzes the advantages and disadvantages of linear induction motor,linear switched reluctance motor and permanent magnet linear motor applied to the driving system of rail transit.Secondly,the basic structure and working principle of the motor are analyzed in detail.Based on the coupling modulation effect of magnetic field,the relations among the logarithm of permanent magnet pole,the number of secondary teeth and the logarithm of air gap fundamental wave magnetic field are derived,and the winding connection mode is determined to design the primary stage structure of the motor.Based on the magnet motive force permeability model of MBCPPMUELM,the air gap magnetic density of MBCPPMUELM is analyzed.By deducing the motor power size equation and the electromagnetic thrust equation,the key parameters that can significantly affect the motor thrust performance are determined,and the electromagnetic design scheme of MBCPPMUELM is determined.Thirdly,the magnetic field of the motor is analyzed and calculated.The subdomain is divided into three parts according to the material characteristics.Based on the subdomain analytical model,a general analytical method is established to solve the air gap subdomain,permanent magnet subdomain and primary stator slot subdomain of MBCPPMUELM.According to the harmonic analysis of air-gap magnetic field,the principle of magnetic field modulation is explained in detail,and the results of subdomain analytical model analysis are compared with the results of ANSYS and Maxwell finite element analysis from two aspects of air-gap magnetic density distribution winding inductance of the motor,and the accuracy of the analytical method is verified.The results are in good agreement with the results of finite element method.Finally,the performance comparison of MBCPPMUELM is studied.This paper studies three typical topological structure forms,and makes a comparative analysis of magnetic field density distribution,magnetic field line distribution,electromagnetic thrust and other operational characteristics by means of finite element analysis,proving the prominentadvantages of the proposed topological structure in magnetic field modulation and electromagnetic thrust.The influence of different structure parameters such as pole arc coefficient of secondary magnetic barrier tooth,rotor guide bar layer number of motor,permanent magnet installation position in stator on the motor magnetic field and thrust is studied,so as to complete the optimization of electromagnetic design parameters,which laid a foundation for the optimization design of MBCPPMUELM and further promotion and application.