Analysis Of Linear Induction Motor And Electromagnet For Low-Speed Maglev Train

With the rapid development of urban rail transit,medium-low speed maglev train as an enmerging transportation system,is attracting extensive attention.It employs single-sided linear induction motors(SLIMs)for traction,and the suspension is realized by electromagnet.It has many advantages including simple structure,strong climbing ability,low noise,low pollution and safety,hence it has a good application prospect and becomes a research hotspot.In this thesis,the research is focus on the SLIMs and suspension electromagnet.The basic structure,working principle of SLIMs,edge effects and T-type equivalent circuit(EC)model are introduced in detail.On this basis,the main contributions in this thesis are as follows:Firstly,in order to further analyze the characteristics of SLIMs,this thesis aims to propose an improved EC method,which comprehensively considers the transverse edge effect,secondary end shape,saturation effect,the thrust force and normal force of SLIMs are predicted under braking and traction conditions accurately and quickly,the effect of current,speed and slip frequency on its performances is also analyzed.Comparison with the traditional T-type EC model,the experiments and finite element model(FEM)results validate those of the improved EC method.In addition,in order to further reduce the transverse edge effect of SLIMs,this thesis proposes a novel SLIMs with double-s lit secondaries,which has the advantages of simple structure,large thrust and low loss.The eddy current effect of double-si it secondaries is analyzed,the parameters are optimized by FEM,and the air gap flux density,eddy current,thrust force and normal force of this SLIMs are calculated,respecti,vely.By comparing to those of SLIMs with cap-solid secondary,the results verify the effectiveness of proposed novel SLINMs.In addition,it is found that adopting middle bar can obviously ilmpro?ve the performances and increase the mechanical strength,which is more suitable for medium-low speed Maglev trains.Finally,for the suspension electromagnet,a 3D FEM is built,and the effects of current and lateral displacement on the levitation force and guidance force is studied.The weakening effect of eddy current effect in F-rail on electromagnetic force at different speeds is also analyzed.In addition,a new hybrid suspension electromagnet is proposed,which can effectively improve the suspension performance under the limitation of certain size and material.