| Eddy current braking is now recognized as the most promising brake system for the next generation of high-speed trains because it has no electrical restrictions and can be used on trailers without motors,which has a lot of room for research and development.This article focuses on the research of the rotating permanent magnet eddy current braking technology applicable to non-powered vehicles.First,it introduces the development of domestic high-speed railway technology.By comparing various train braking methods,the advantages of the rotating permanent magnet eddy current brake device in the railway brake system are analyzed.Based on the research status of eddy current braking technology at home and abroad,a research plan for a permanent magnet eddy current retarder device applied to domestic CRH380 B EMU braking is proposed.The related knowledge of CRH380 B EMU was briefly introduced,and the relevant data was collected to analyze the braking conditions when it was downhill.It was obtained that the eddy current braking needs to provide a braking torque of 7k N ? m.According to the structural characteristics of CRH380 B EMU and its trailer bogie,the overall scheme of permanent magnet eddy current retarder is designed.At the same time,on the basis of expounding the working principle of the device,the corresponding structural design and calculation were done.Finally,considering the high temperature during braking,a water-cooled heat dissipation structure is designed to reduce the temperature rise during operation by cooling water,preventing overheating from affecting the braking performance of the device.By analyzing the basic characteristics and parameters of the permanent magnet m aterial,N42 UH is selected as the permanent magnet material.Based on the structural characteristics of the permanent magnet eddy current retarder,the equivalent magnetic circuit is analyzed and drawn,and the magnetomotive force and reluctance are calculat ed.Finally,the formulas of braking power and braking torque are derived theoretically,and the relevant parameters that affect the magnitude of braking torque are obtained.Using Ansys Maxwell finite element electromagnetic field analysis software to est ablish a simplified model,the electromagnetic field finite element simulation calculatio n of the permanent magnetic eddy current retarder under the transient magnetic field,t he characteristics of the eddy current density,magnetic induction intensity distribution and braking torque of the transmission components were analyzed.By studying the rel ationship between the braking torque generated by the permanent magnet eddy current retarder and various factors,the corresponding structural parameters were optimized.Aiming at the fact that the copper disk generates a large amount of heat while g enerating braking torque,the transient temperature field of the permanent magnet eddy current retarder is analyzed and calculated.Using Ansys Workbench software to study the heat dissipation effect under air-cooled and water-cooled conditions.Under the condition of water-cooling,the temperature when working under different air gap lengths is analyzed to determine the appropriate air gap distance,so that the working temperat ure of the permanent magnet can keep within the allowable range. |
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