Influence Of Track Excitation On Dynamic Characteristics Of New Medium-low-speed Maglev Train

In this paper,a new medium-low-speed maglev train was selected as the research object.Firstly,the structures of levitation bogies were briefly introduced and analysed considering the structure characteristics of levitation bogie for HSST medium-low-speed maglev train.Secondly,the levitation control system of maglev train was analysed,and a mathematical model was developed for the levitation control system of medium-low-speed maglev train.Thirdly,tests were made with a single levitation bogie vehicle-coupled-guideway coupling vibration test rig,for analysing and comparing the influences of vehicle-coupled-guideway coupling vibrations on the levitation bogies between a new medium-low-speed maglev vehicle and a HSST medium-low-speed maglev vehicle.Based on the principle of single levitation bogie vehicle-coupled-guideway vibration test rig,a dynamic model of such test rig was developed considering the vertical motion only with the software of MATLAB/SIMULINK,for dynamic response analyses.At last,a dynamic model was developed with the software of SIMPACK for a new medium-low-speed maglev vehicle with active vibration control,to analyse its dynamic response characters.1.The levitation bogie of new medium-low-speed maglev train mainly consists of the following parts: the structure of levitation bogie(including longitudinal beam,bracket arm,anti-rolling beam),emergency supporting wheels,levitation electromagnets,linear traction motors,braking systems and suspension components.Compared with the HSST medium-lowspeed maglev train in Japan,the levitation bogie of the new medium-low-speed maglev train has optimised designs,including intermediate air-springs,lengthened linear motors and the single anti-rolling beams.The mechanical performance of the levitation bogie was improved,so that the train has higher running speed and lower vehicle-guideway dynamics.2.Levitation control systems are of essentially importance for the levitation stability and safety of maglev trains.Electromagnetic forces are inversely proportional to levitation gap,which would cause the instability to electromagnetic levitation control systems.The feedback regulation control of position,velocity and acceleration was introduced in the levitation control system,and real-time monitoring of levitation gaps and levitation electromagnet accelerations were made with gap sensors.The levitation force of the levitation electromagnet is able to be adjusted actively,and the vehicle levitation stability is able to be ensured.3.It was validated by the vehicle-coupled-guideway vibration tests that compared with HSST medium-low-speed maglev vehicles,the new medium-low-speed maglev vehicles have the advantages of heavy loads and low vehicle-guideway dynamics.Simulation results from the vertical dynamic model of the single levitation bogie test rig indicated that such model has the characteristics of low frequency follow and high frequency suppression to active excitation.When the frequency of the active excitation is close to the natural frequency of the track beam,the occurred resonances would cause severe vibration.4.The new medium-low-speed maglev vehicle shows excellent ride comforts under the random track irregularities under straight track conditions.The levitation gap would be stabilized at about 8mm with good vehicle dynamic performance.When the periodic excitation frequency satisfies f(29)1.1v/ L,the stability and rid comfort of such vehicle are able to be ensured within acceptable ranges.For curve conditions with random track irregularities,the vehicle is able to negotiate the curves of R150 m,R300m and R600 m at the speed of 53km/h,75km/h and 105km/h respectively,with sufficient stability and good vehicle dynamic performance,such as small vertical carbody accelerations and small carbody roll angles.