Research On Semi-active Control Of Hunting Movement In High-speed Trains

With the rapid increase of high-speed trains and operation mileages,some EMUs appear to have different degrees and different characteristics of hunting instability.The hunting instability of high-speed trains is divided into the primary-hunting and the secondary-hunting,which affect ride performance and the reliability of components,or even may lead to derailment of vehicles;moreover,there is a contradiction between the requirements of the main suspension parameters of the bogie for the primary-hunting and the secondary-hunting.However,at present,there is not much optimization space for hunting movement of high-speed trains through passive suspension parameters optimization,and there is no unified solution to the contradiction between the parameters of the primary-hunting and the secondary-hunting.The semi-active control method of yaw damper is studied in this paper to solve the problem of hunting instability of high-speed trains.The specific contents include the following aspects:1.The dynamic model of multi-freedom nonlinear vehicle system is established.The static and dynamic characteristics of two kinds of yaw dampers are compared and analyzed.The effect of stiffness and damping of yaw dampers on stability of high-speed vehicle is studied.The yaw damper model and its semi-active control module are built with Simulink software,and a joint simulation model of Simpack and MATLAB/simulink is established.2.Using the dynamic simulation method considering the random factors,the distribution of vehicle system suspension parameters,wheel-rail matching,wheel rail interface,track disturbance,environment temperature and so on,hunting instability of the vehicle is simulated.Considering the change range of boundary conditions in operation as comprehensive as possible,the vibration response and hunting motion characteristics of vehicles are analyzed according to the simulation results of the primary-hunting and the secondary-hunting.This paper introduces the simulation method of dynamic simulation with random factors,and simulates the hunting instability simulation of high-speed vehicles,and simulates the primary-hunting and the secondary-hunting,and analyzes the vehicle response and hunting characteristics of the two kinds of hunting movements.The evaluation index of the narrow band random process is used to judge whether the vehicle has hunting movement or not,and the relationship between the indexes is analyzed,and the evaluation method of hunting movement is summed up:the primary-hunting is determined simultaneously by the ride comfort indexes of the front and rear car body and the frequency of gravity center of the lateral acceleration of the car body.When the maximum filtered value of lateral acceleration of the frame and the frequency of gravity center of the transverse acceleration of the vehicle body are used simultaneously to determine whether the secondary-hunting motion has occurred.The rationality of hunting evaluation method is verified by simulation results.3.Using the on-off control strategy to control the yaw dampers,the yaw dampers above each side of the bogie are set as the controlled dampers,and whether the above yaw dampers work or not according to the judgement results of hunting:when the car body is hunting,the above yaw dampers don't work;when the bogie is hunting,the above yaw dampers work;when there is no hunting,the above yaw dampers maintain the state of the previous judgment result.The below yaw dampers work normally in any state.The parameters of single side yaw dampers and two sides yaw dampers working in parallel are optimized respectively.The simulation results of the primary-hunting,the secondary-hunting and no hunting show that the proposed control method is effective and can suppress the instability of high-speed vehicles.