Research On Braking And Temperature Rise Characteristics Of Linear Induction Type Rail Eddy Current Brake

At present,the highest velocity of high-speed wheel-rail trains in commercial operation in China can reach 350 km/h.The main braking methods are regenerative braking and friction braking.This braking method that relies on the adhesion between the wheels and rails will cause serious wear of the wheels and rails during the braking process,which greatly increases the cost of repairs of the wheels and rails.Produces louder noise,which affects the comfort of the ride.The adhesion between the wheel and the rail will drop sharply under severe weather such as rain and snow,seriously affect the safety of riding.In addition,China’s "Outline for Building a Powerful Transportation Country" clearly proposes to further research 400 km/h high-speed wheel-rail passenger train system,with the increase of high-speed train speeds,friction braking is close to the limit of speed is extremely challenging to the requirements of braking technology.Therefore,it has great significance to study a braking method that does not rely on wheel-rail adhesion,frictionless,noiseless,and not affected by harsh environments such as rain and snow.The eddy current brake can make up for these shortcomings.Aiming at the technical characteristics and shortcomings of the current braking methods of high-speed trains and urban rail trains,as well as the existing DC-powered rail eddy current braking,combined with the principle of linear induction motors,this thesis research a braking method that is more suitable for high-speed trains.It is called linear induction type rail eddy current braking.And then,corresponding research on braking and temperature rise characteristics of system conducted by the way of combining theoretical analysis,finite element simulation and experiment.First,the analytical model of linear induction type rail eddy current brake was established based on equivalent magnetic circuit method,the magnetic induction intensity of the air gap magnetic field and the induced current on the rail surface were solved,and the eddy current braking force formula was deduced according to the energy method.The factors that affect the braking performance of the brake are initially explored.Secondly,a two-dimensional finite element model of the linear induction type rail eddy current brake was established,and the influence of the excitation current,excitation frequency,operating speed,working air gap and other related parameters on the braking performance was studied parametrically,and its influence law was deeply explored and revealed.The results show that the best excitation frequency of the linear induction type rail eddy current brake is30 Hz,and it can also produce a larger braking force in the low-speed area.The braking force characteristics with different pole pitch and the effect of the synergy of traveling wave magnetic field speed and train running speed on braking performance are studied.The magnetic-thermal coupling model of linear induction type rail eddy current brake is established,and the temperature rise of the rail caused by the thermal effect in the braking process with different working conditions is solved and analyzed.The factors that cause the temperature rise and the influence law are studied.It also demonstrates the feasibility of applying the brake in long-term high-speed railway lines in our country under the influence of temperature rise.Finally,a linear induction type rail eddy current brake experimental platform that simulates high-speed operation is designed and build,the braking performance of the eddy current brake is studied.The maximum speed of the experiment can reach 113 km/h,the maximum braking force can reach 200 N,and the braking effect is obvious,the braking trend is consistent with the simulation results,it further confirming the feasibility of the linear induction type rail eddy current brake in the field of high-speed railway braking.