Design And Optimization Of Permanent Magnet Linear Motor In High Temperature Superconducting Maglev Vehicle

High temperature superconducting(HTS)magnetic levitation is a passive and self-stabilizing system.It only needs simple control to produce stable levitation force and guidance force.It also has the advantages of high reliability,simple structure and small size,so it has broad application prospects in the field of rail transit.Permanent magnet linear synchronous motor(PMLSM)is suitable for high-speed applications because of its high efficiency,high thrust density and good controllability.It is of far-reaching significance to apply PMLSM to HTS magnetic levitation for high-speed train driving.Firstly,curve fitting method and piecewise approximation method are used to solve the train's non-linear motion model,and the expressions of train speed and acceleration under different running conditions are calculated.At the same time,combined with the running resistance and acceleration process,the thrust required for train operation is analyzed,which simplifies the train motion model and lays a foundation for the design of linear motor in Maglev train.Secondly,the equivalent surface current method of armature winding and the equivalent magnetization intensity method of permanent magnet are used to lay the model of PMLSM.The Poisson equation of armature winding,permanent magnet and air gap region is established.The analytical magnetic field under slotless armature reaction and permanent magnet excitation is deduced by using boundary conditions.The correctness of the analytical magnetic field is verified by comparing the drawn analytical magnetic field model with the simulation results of the finite element software MAXWELL.Aiming at the system requirement of HTS maglev train,and based on the structure design method of traditional rotary motor and linear motor,the parameters of permanent magnet synchronous linear motor are designed in detail.A high-power linear motor is designed to meet the requirements of HTS maglev system,and its electrical parameters and performance index are analyzed.The results show that the motor has power factor and performance index.Advantages of high efficiency.In addition,because the stability requirement of HTS maglev train at high speed is high,this paper studies several thrust ripple suppression technologies based on the structure design of motor.By analyzing the pitch coefficient of winding,it is found that the double-layer short-distance winding with pitch coefficient of 5/6 can effectively suppress the 5th and 7th harmonic components of magnetic potential.Based on fractional slot theory,an unequal pole distance structure of linear motor is proposed,which greatly reduces the thrust ripple and reduces the thrust ripple to less than 3%.A method to determine the pole distance of the mover is proposed to achieve the best design of the unequal pole distance structure.By studying the influence of groove depth,groove width and groove shape on thrust fluctuation,it is found that rectangular groove has the best effect of restraining cogging torque.Several optimumdesign methods have achieved good results in suppressing thrust fluctuation,which provides a reference for the design of HTS maglev linear motor.Finally,based on the design method of large system motor,the same type of small prototype is designed,and a prototype experiment platform of permanent magnet synchronous linear motor is built.The operation effect of the motor is analyzed experimentally and compared with the simulation results,which verifies the correctness of the motor design in this paper.