Design And Analysis Of Ironless Permanent Magnet Linear Synchronous Motor For Medium Speed Maglev Train

The medium-speed maglev train has the advantages of small traveling radius,strong climbing ability,low maintenance cost and high safety factor.It has become a strong competition scheme for urban and intercity transportation in the future,and has a good application prospect.It was included in the national key research and development plan in 2016.Linear motor for traction is one of the key technologies of medium speed maglev train.Long stator Halbach magnetic pole ironless permanent magnet synchronous linear motor(IPMLSM)can better solve the related problems caused by the existing short primary LIM as the speed increases.This paper focuses on the design and analysis of long stator Halbach magnetic pole IPMLSM.The main work is as follows:Firstly,the traction scheme of medium-speed magnetic levitation is introduced,and the main parameters of the preliminary design of the linear motor are given.The running resistance of trains at different speeds is calculated by using the classical model,and the traction power requirements are given according to the performance index requirements.Combined with the size limitation of traction and suspension schemes,the design requirements of long stator Halbach magnet IPMLSM are obtained.Secondly,the basic structure of long stator Halbach magnetic pole IPMLSM and the arrangement of Halbach magnetic pole are expounded,and the working principle of the motor is explained.On this basis,the external magnetic field of Halbach magnet pole is analytically calculated by using the superposition calculation method of equivalent surface current and the solution method of Fourier series partial differential equation,and compared with the finite element simulation to show the advantages and disadvantages of the two analytical methods.Then the analytical expressions of thrust,normal force and no-load back EMF are given.Thirdlly,the basic structure of the motor and the arrangement of Halbach array are described,and the working principle of the motor is explained.On this basis,the external magnetic field of Halbach permanent magnet array is analytically calculated by using the superposition method of equivalent surface current and the solution method of Fourier series partial differential equation,and compared with the finite element simulation to obtain the advantages and disadvantages of the two analytical methods.The analytical expressions of thrust,normal force and no-load back EMF are given.Finally,through the analytical calculation of the armature magnetic field of the long stator Halbach magnetic pole IPMLSM,the reactance and leakage reactance of the motor are obtained.Combined with the phasor diagram,the analysis method of the motor terminal voltage,power factor and traction efficiency is obtained.The influence of main parameters including air gap length,pole distance,permanent magnet height,conductor radius and stator segment length on motor performance is analyzed,and the optimization direction of each parameter is given.On this basis,the multi-objective genetic algorithm is used to globally optimize the IPMLSM structure of long stator Halbach magnet pole,and a three-dimensional finite element model is established for verification.