| Taking the electromagnetic eddy current brake of high-speed maglev train as the research object,this thesis clarified the principle of electromagnetic eddy current braking based on the introduction of research status of electromagnetic eddy current braking system.The braking force and normal force characteristics of eddy current braking system were analyzed,the influence of some basic parameters and structural parameters on the system characteristics were studied,the application feasibility of permanent magnet eddy current braking was analyzed,and finally an optimization scheme for the eddy current braking system was proposed.The main research work is as follows:(1)The principle of electromagnetic eddy current braking was clarified,and the similarities as well as differences of the eddy current brakes applied to ICE-3 high-speed EMU and Shanghai TR-08 high-speed maglev train were compared.The design points of the eddy current braking system of high-speed maglev trains were summarized;(2)A two-dimensional mathematical model of eddy current braking system was established,the analytical expression of the braking force was derived through the analysis of the magnetic circuit and the calculation of the induced eddy current,and the heat transfer process of the system was analyzed.The influence of running speed,exciting current,number of coil turns,air gap,relative permeability of iron core and relative permeability of the induction plate on the braking force characteristics were analyzed through variable control method;(3)The electromagnetic-thermal coupled finite element simulation model of the eddy current braking system was established,and the validity of the model was verified based on experimental data;the effects of basic parameters such as running speed,exciting current,number of coil turns,air gap,failure state of magnetic pole,as well as structural parameters such as the slotted structure of the primary iron core,the thickness of the secondary induction plate,the layered structure of the secondary induction plate,the primary and secondary materials,and the composite secondary structure on braking characteristics was studied,and an optimization scheme of eddy current braking system was proposed;(4)A permanent magnet linear eddy current brake device with hydraulic lifting mechanism was proposed on the basis of the existing electromagnetic eddy current brake device,the permanent magnet eddy current brake model corresponding to the electromagnetic eddy current brake model was established,and the above two models were compared based on electromagnetic-thermal coupling simulation;(5)According to the electromagnetic simulation results of eddy current braking,the dynamic model of eddy current braking system and 450 km/h high-speed maglev vehicle were established,the force and state of eddy current brake in each stage of emergency braking processes were analyzed;and the braking time,braking distance,longitudinal acceleration and dynamic performance of high-speed maglev vehicle under the original scheme and the optimized scheme of the eddy current braking system were comparative studied.Through the above research,this thesis can provide a reference for the design of eddy current braking system in the field of rail transit and its application in the high-speed field. |
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