Simulation Of Dynamic Performance For High Speed Train Under Traction And Braking Conditions

With the increase of train speed,traction and braking force need to be continuously increased.Traction and braking conditions are two unsteady conditions.Under these two conditions,the dynamic performance of the train becomes worse,which often leads to accidents.The previous studies mainly considered the dynamic performance of high-speed trains under constant speed conditions,and the dynamic performance research involved in traction and braking conditions is still relatively small.Therefore,this paper focuses on the analysis of dynamic performance under traction and braking conditions so as to improve the dynamic performance indicators,which have been greatly affected under traction and braking conditions.The main research contents are as follows:(1)A vehicle dynamics model for high-speed trains is established.Firstly,taking the single-section power train as the research object,the wheelset dynamics model is established by analyzing the geometric relationship and force between the wheel and rail.Secondly,the dynamics model of structure,suspension system and the train body are established based on the train topology and dynamic parameters.Thirdly,considering the constraints of the connection of various components,the vehicle dynamics model is assembled,and the measured excitation data of the Wuhan-Guangzhou line is added to the track.(2)A co-simulation model for entire high-speed trains is established.Considering the characteristics of traction,braking and resistance of trains,a co-simulation model based on Dymola/SIMPACK is established by adding the mathematical models of traction,braking force and running resistance to the whole train dynamic model.(3)The dynamic performances under six working conditions including constant speed linear track,constant speed curve track,traction linear track,traction curve track braking linear track and braking curve track are analyzed and compared.The results show that:Under constant speed condition,the dynamic indexes of the train running on the curve track are larger than that on the linear track.When the train is running on a linear track,the application of traction or braking force has little effect on the dynamic performance,which can be ignored.When the train is running on a curved track,the magnitude and direction of the longitudinal creep force of the wheel will be changed.It will be difficult to cross the curve when the traction force and braking force is applied.What's more,when the braking force is applied,the combined force of the lateral creep force of the left and right wheels increases,and the lateral stability index increases significantly.At this time,the unstable is most likely to occur.(4)A suspension system optimization method based on the skyhook damping control strategy is proposed.Aiming at the problem that the high-speed train has poor lateral stability index under the braking condition,the skyhook damping control strategy is selected to optimize the train suspension system.A semi-active controller model based on the skyhook damping control strategy is added to the train dynamics model for co-simulation.The results show that the optimized train model can significantly reduce lateral vibration.No matter the train is running on the linear or curved track,the lateral acceleration is significantly reduced,the lateral stability index is improved.