Magnetic Force Characteristics Of The Superconducting Electrodynamic Levitation And Dynamic Simulation Of The Superconducting Maglev Vehicles

As a new-type rail transport,the superconducting electrodynamic suspension(EDS)maglev train is different from the electromagnetic suspension(EMS)maglev train and the conventional wheel-rail train.The superconducting EDS maglev train has the advantages of high speed,large levitation gap,and no need for active control,thus it has good prospects to be applied in the high-speed/ultra-high-speed ground transportation.However,for the electrodynamic levitation system,which is most important to stable operation of the superconducting EDS maglev train,has complex dynamic interaction between the superconducting magnet and the ground coils due to their complex electromagnetic environment.Thus,the superconducting electrodynamic suspension is always be simplified to a linear spring,so that the dynamic behavior of the superconducting EDS maglev vehicles cannot be accurately simulated.In this thesis,magnetic force characteristics of the superconducting EDS system are investigated to develop an analytical calculation model of the nonlinear magnetic forces.Subsequently,it is applied in dynamic simulation of the superconducting maglev vehicles.dynamic performances of the maglev vehicles are analyzed,and the optimum study of suspension parameters is carried out.Firstly,this thesis analyzes the structure of superconducting electrodynamic suspension system.Using the dynamic circuit theory,the equivalent circuit models are built to derive analytical expressions of the magnetic levitation force,the magnetic guidance force and the equivalent damping.In the case of the electrodynamic suspension system of the Japanese MLX01 superconducting maglev vehicles,the magnetic levitation and guidance forces under different conditions are calculated,and the relationship curves of the magnetic forces and the equivalent damping with the running speed,the levitation gap and the guidance gap are presented to reveal mechanical characteristics of the electrodynamic levitation system.The above-mentioned research provides a basis for dynamic modeling and simulation of the superconducting maglev vehicles in this thesis.Secondly,the bogie structure of the superconducting maglev vehicles is introduced,and then the dynamic model including the calculation module of the nonlinear electrodynamic magnetic forces is established using the SIMPACK software and the Simulink plug-in.Meanwhile,the track irregularity sample is calculated according to the Chinese Standard “PSD of ballastless irregularities of high-speed railway”(TB/T 3352-2014).Using the dynamic model of the superconducting maglev vehicles,dynamic response of the maglev vehicles passing through the straight tracks and curved tracks at different running speed are simulated.The simulated results indicate that the running speed has a significant influence on dynamic performances of the superconducting maglev vehicle.When the superconducting EDS maglev vehicle passes through the curve tracks,the change of levitation and guidance gaps of the superconducting magnets is small.It indicates there is little likelihood of a mechanical collision between the vehicle and the curved track.Furthermore,comparing the simulated results from the nonlinear magnetic force model with the equivalent linear spring model,it can be found that the simplified linear magnetic force model lead to the worse lateral ride quality,while the vertical ride quality almost has no change.Finally,the influence of the primary and secondary suspension parameters on dynamic performances of the superconducting maglev vehicle are studied.The simulated results show that the primary suspension stiffness has little influence on the ride quality,and the small secondary suspension stiffness can improve the vertical ride quality of the maglev vehicles.Since small damping of the superconducting EDS levitation system causes the poor ride quality,the operating principle of the damping coils installed on the superconducting magnet is introduced,and dynamic response of the superconducting maglev vehicle with the damping coils are analyzed.It is found that the damping coils can improve effectively the vertical ride quality of the superconducting maglev vehicles.