Analysis Of Magnetic Force Characteristics Of SML&PML For Hybrid Maglev

In order to improve the market competitiveness of maglev technology,the model of hybrid maglev involved superconducting magnetic levitation(SML)and permanent magnetic levitation(PML)has been put forward.The hybrid maglev takes advantage of self-stability in SML and large load capacity in PML,achieving the goal of complementary advantages.Compared with the single maglev mode,the requirements of hybrid maglev for each subsystem are different.On the one hand,the SML subsystem should emphasize on enhancing guidance performance.On the other hand,the PML subsystem should increase the levitation force and reduce the lateral force.Therefore,based on the performance requirements of hybrid maglev for each subsystem,this thesis has put forward the targeted optimization design on permanent magnets and superconductors on the vehicle.Also,the magnetization direction of Halbach magnet rail was modified.Firstly,the performance of high-temperature superconducting(HTS)bulks in the vertical laying mode was studied in this thesis.The experiments were conducted to study the effect of seed-face orientation on the magnetic force characteristics and the magnetic coupling effect between the vertical HTS bulks.The results show that the effect of seed-face orientation on the levitation force is smaller,while larger on the guidance force.The guidance force can be improved by setting the c-axis of HTS bulk perpendicular to the main magnetic field.In addition,the magnetic coupling effects on the levitation force and the guidance force are different under different external magnetic fields.Since the magnetic coupling effect cannot be ignored,it is impossible to predict the force of vertical HTS bulk arrays with the force sum of single bulk.Secondly,the performance of HTS bulks in the mixed laying mode was studied in this thesis.The results of experiments show that the magnetic coupling effect of ‘horizontal-verticalhorizontal’ mode is smaller,while ‘vertical-horizontal-vertical’ mode’s is larger.Based on the analysis on HTS bulks’ magnetic force characteristics in the vertical and mixed laying mode,an optimized design of SML subsystem applied to the hybrid maglev is proposed.The magnetization direction of Halbach magnet rail was modified to increase the vertical component of magnetic field,so that the guidance performance will be improved.Thirdly,the magnetic force characteristics of PML system was studied in this thesis.Three optimization indexes,corresponding to the unit-length levitation force,the lateral-to-levitation force ratio,and the conservation rate of levitation force,were proposed.Then the magnetic field of Halbach magnet rail and permanent magnets on the vehicle(PM-V)were described by approximation methods.The levitation force and the lateral force were calculated with the analytic expressions.The dimension of PM-V was optimized and the results were verified by finite element method(FEM).Afterwards,the magnetic field of Halbach magnet rail,especially at the both ends was analyzed in detail by FEM,and the shape of PM-V was optimized.The results show that the unit-length levitation force increased by 58%,the levitation-to-lateral force ratio increased by 59% and the conservation rate of levitation force increased by 11.5%.The load capacity and stability of the hybrid maglev were improved.