Research On Nonlinear Suspension Force Modeling And Vibration Characteristics Of Hybird Magnetic Levitation System

The maglev train,which has no mechanical contact wear,a high running speed,safety,reliability,and environmental protection,is one of the rail transit hotspots.The high temperature superconducting pinned magnetic levitation technology relies on the macroscopic suspension force between the permanent magnet and the high temperature superconductor to achieve suspension.It has the advantages of self-stability,low power consumption,and the lack of a control device.However,the cost of this suspension method is high,and the suspension cost is prohibitively expensive.Electric suspension,as opposed to high-temperature superconducting pinning suspension,relies on the principle of ’Lenz’s law’ to achieve suspension.This suspension method is appropriate for the train’s high-speed running stage,but its suspension force is weak in the low-speed stage.As a result,wheel-rail support is still required during the initial stage of train operation,which contradicts the original intention of ’non-contact’ operation.In order to investigate better suspension properties,this thesis combines the two suspension systems of high temperature superconducting pinning suspension and electric suspension to form a hybrid magnetic suspension system and investigates its nonlinear vibration characteristics.Firstly,using the high temperature superconducting pinning magnetic levitation test equipment SCML-01,the levitation force data are acquired under various levitation gaps and fitted to the popular cubic nonlinear model to get the empirical formula for levitation force.The electric suspension force data is then calculated and simulated using Maxwell finite element software,and it is fitted to the linear model as an empirical formula.The hybrid magnetic levitation system’s structure has been planned,and the motion differential equation has been created.The multi-scale approach is used to get the approximate answer.The approximation of the solution expression results in the parameter feasible area fulfilling the safety and comfort index of the train operation.According to the study,the system parameters have a feasible zone that satisfies the aforementioned signs.But,when the maglev train’s operating speed increases,the viable region shrinks and eventually fails at 853 km/h.The hybrid magnetic levitation system’s kinematic equation under dual-frequency excitation is then established.The chaotic threshold of the system is calculated using the Melnikov technique.The system may experience chaotic motion,according to numerical verification and dynamic modeling.A strategy to lessen the likelihood of chaotic motion in the system is provided by examining the impact of system characteristics and operational parameters on the chaotic threshold.The Lyapunov stability theorem is then used to examine the stability of the hybrid magnetic levitation system’s equilibrium point while taking into account the secondary suspension.The Taguchi method is used to optimize the parameters,which can also serve as a guide for the parameter design of the hybrid magnetic levitation system.The maximum amplitude of the suspension frame under harmonic excitation and the maximum acceleration of the carriage are taken as the optimization objectives.