| The high-temperature superconducting(HTS)maglev,which was born in China,owns the characteristics of integrated levitation guidance,no active control requirement,environmentally friendly and energy saving,and is expected to become the promising high-speed maglev rail transit in the future.However,related researched have indicated that the low damping characteristic of HTS maglev may lead to large amplitude vibration when encountered with external disturbance,and may threaten the stability and safety of vehicle operation.Therefore,it is necessary to find an approach to increase the damping of the HTS maglev system and suppress vibration.As a kind of no contact vibration isolator,electromagnetic shunt damper(EMSD)has large research value because its working character matches the HTS maglev system well.In this thesis,aiming at improving the damping of the HTS maglev system and reducing the vibration,the negative resistance module is introduced into the electromagnetic shunt damper to solve the issue that the traditional resonant type EMSD can only suppress one single mode and the unrealistic requirements of large capacitance and inductance.The negative resistance electromagnetic shunt damper can be installed on the HTS maglev frame as an independent damping device,which is more suitable for practical application.Firstly,this paper analyzes the working principle of electromagnetic shunt damper from the perspective of mathematical analysis,and deduces the mathematical model of electromagnetic shunt damper and figure out the influence of parameters change on damping system.Then,the vertical dynamic equation of high temperature superconducting maglev system with electromagnetic shunt damper is established.The formula shows that the electromagnetic damping force produced by electromagnetic shunt damper provides additional damping for the system.Then,the principle of the negative resistance electromagnetic shunt damper is analyzed,and the realization circuit of the negative resistance is simulated and designed,and the value of negative resistance is optimized based on the fixed point theory and the root locus graph.Then,the effect of electromagnetic shunt damper is simulated and analyzed by finite element software.The relationship between the electromechanical coupling coefficient and the distance between the coil and the permanent magnet track is obtained by simulation.The influence of the value of resistance of the circuit on the induced electromotive force and electromagnetic damping force in the coil is clarified.The influence of different coil lateral positions is simulated and analyzed.Finally,the vibration experiments are carried out based on the established vibration test platform.The experimental results show that the negative resistance electromagnetic shunt damper can effectively suppress the vibration of the HTS maglev system.In a certain range,the damping effect of EMSD increases as the value of negative resistance increases,and it has the strongest control effect when the resistance value reaches the optimal negative resistance value.Subsequently,its effect will decrease with the further increase of negative resistance.As the negative resistance continues to increase until the inherent resistance of the coil is completely offset,the vibration will aggravate.Firstly,the influence of different coil connection modes on the experimental results is verified by experiments and the best coil connection mode is established.In the single guideway experiment,when the negative resistance is-20Ω,the maximum acceleration amplitude of the suspension model decreases from 4.5 m/s~2 and 4.9 m/s~2 to 0.6 m/s~2 and 0.8 m/s~2 respectively compared with the situation without EMSD.At the field cooling height of 40 mm and 30 mm,the maximum vibration acceleration decreases by 87%and 84%,respectively.When the field-cooling height is 30 mm and the negative resistance value is-35Ω,the maximum acceleration of the suspension model decreases from 3.1 m/s~2 to 0.5 m/s~2,a drop of 84%is observed.Moreover,the time of the system restore to stability was significantly reduced from 6 s to 0.5 s.This research is expected to provide a reference for the further engineering application of HTS maglev system. |
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