Design And Research Of Hybrid Excitation Linear Motor For Rail Transit

In recent years,with the development of the permanent magnet linear motor,many new linear motors have been proposed.The most representative of new linear motors are the doubly salient permanent magnet linear motor(LDSPM),the flux reverse permanent magnet linear motor(LFRPM)and the flux switched permanent magnet linear motor(LFSPM).The most remarkable feature of the motors are that the primary mover of the motor is equipped with permanent magnet and armature windings,while the secondary stator of the motor is only composed of magnetic conductors.The whole structure of the motor is simplified,and with the use of high performance permanent magnet,this kind of motor has higher power density and efficiency,so it is perfectly suited for urban rail transit systems.However,the air-gap magnetic field of the permanent magnet linear motor is only produced by permanent magnet,which leads to air-gap magnetic field of the permanent magnet linear motor keeps constant,and can not offer high-speed constant-power operation,nor can it maintain high efficiency over a wide operation range.The purpose of this paper is to propose a new hybrid excitation linear motor,this new motor has the advantages of simple structure and higher power density of linear synchronous PM motors.The air gap flux density can be regulated by changing the magnitude and direction of DC excitation current,so it can not only reduce the drive system cost but also offer controllable electromagnetic force and EMF.This is helpful to extend the motor speed range and improve the system efficiency at different loads and speeds.The proposed motor is very suitable for the long stator field such as urban rail transit.The main contents of this paper are as follows :(1)This paper introduces the driving circuit of linear motor in the field of rail transit at home and abroad,and studies the development status of linear motor,and puts forward a new type of HEPLM motor aiming at the deficiency of linear motor at present.(2)According to the basic theory of modularization and magnetic circuitcomplementary LFSPM motor,the topological structure and operation principle of new HEPLM motor is analyzed,and the mathematical model of HEPLM motor is deduced.(3)A general design method for HEPLM motor is presented.The main dimensions of the motor are designed from the point of view of output power.(4)By using JMAG software,the two-dimensional finite element model of HEPLM motor is established.The simulation results show that the proposed HEPLM motor has excellent performance and is fully applicable to the field of rail transit.(5)By optimizing the structure of HEPLM motor to obtain the best motor performance.By switching the HEPLM motor with two different modular,complementary flux switching motors demonstrate the performance of HEPLM motor.