| With the rapid development of the economy and the rapid advancement of society,traditional wheel-rail trains can no longer meet people’s travel needs.High-speed maglev train has attracted the attention of many countries because of its high speed,safety,convenience and high comfort.Since the 1960s,many countries have invested a lot of manpower,material and financial resources to carry out research on high-speed maglev trains.Due to the super-high speed of high-speed maglev trains,conventional contact brakes generate a large amount of heat due to friction during high-speed braking,especially at high-speed emergency braking.The heat is difficult to emit in a short period of time,which can easily lead to high temperature failure of brake devices,and seriously threaten the safe operation of trains and the safety of passengers.The eddy current brake has the characteristics of no friction,long life,high reliability,convenient control,low noise and good stability,and has been widely used in high-speed maglev trains.With the increasing speed of maglev train,the requirement for brake device is more and more severe.How to effectively improve the brake performance and ensure that the brake works in a safe temperature range is particularly important.Therefore,it is of great significance to research the electromagnetic field and temperature field of eddy current brake.Firstly,in order to satisfy the braking requirements of high-speed maglev train,a two-dimensional electromagnetic model is established for a single carriage and a single-side eddy current brake of the train.The influence of air gap length,excitation current,coil turns,material permeability and conductivity on braking performance of eddy current brake is analyzed.The electromagnetic force and loss of guide plate with different thickness are studied.The structure of magnetic pole is optimized to improve braking performance of eddy current brake.Secondly,aiming at the problem that the eddy current brake generates a large amount of heat when it enters a large current,which affects the safe and reliable operation of the brake and the safety of the train,a three-dimensional transient temperature model is established based on the finite volume method,and the transient temperature field of the eddy current brake is calculated.The influence of the excitation current on the temperature of the coil,the inner and outer insulation,the core and the yoke and the brake as a whole is studied,and the temperature at different excitation currents is compared.It also analyzes the effects of ambient temperature changes on the temperature of the brakes and the different parts.Finally,in order to study the influence of different material coils on braking performance and temperature distribution of eddy current brake,the aluminum coil is replaced by copper coil for calculation.The electromagnetic force and temperature of the same number of turns,the same quality of the copper coil and the aluminum coil are analyzed.On this basis,further consideration is given to the improvement of brake performance when the same temperature is raised. |
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