| With the progress and development of society,people’s demand for material and cultural aspects is increasing.The convenience and comfort of travel process has a real impact on everyone’s daily life.As a traditional means of transportation,wheel-rail train has the advantages of heavy load,stable,controllable,and technology leadership.However,under the background of actively advocating environmental protection and high efficiency,it is difficult to solve the problems of noise and speed improvement bottleneck for wheel rail train.At this time,high temperature superconducting(HTS)maglev train with its low power consumption,clean,high running speed and other advantages emerged in people’s view,which provides the possibility for the development of ground transportation in a better direction.At first,the research background and experimental platform of HTS maglev vehicle are introduced,and then the specific research content is shown.In the third chapter,the magnetic resistance characteristics of maglev prototype vehicle in the lowspeed range(v< 40 km/h)are studied.The experimental results show that high magnetic field gradient and fluctuation frequency will not only lead to a sharp increase in the magnetic resistance,but also cause a dramatic decline in its suspension performance,seriously affecting the stability of the maglev vehicle.After the research on running resistance of HTS maglev vehicle at low speed,the dynamic magnetic resistance characteristics at high speed(up to 120 km/h)are studied from the time domain and frequency domain through high-speed rotating maglev testbed.We simulate the vibration curve of the maglev vehicle in running direction using the transient magnetic resistance response curve,and the nonlinear characteristics of the turntable maglev system are analyzed.Through the analysis of the experimental magnetic resistance,it is found that the dynamic magnetic resistance is shown as a positive and negative fluctuation curve,and the fluctuation amplitude increases with the running speed.It was found that the power spectral density curve of magnetic resistance appears multiple peaks at higher speed,accompanied by wide peak phenomenon.Through the calculation of Lyapunov exponent,it is found that the system has chaotic characteristics when maglev vehicle reaches a higher speed at a certain field cooling height(FCH).Chaotic characteristics will lead to the instability of the system,resulting in the unpredictability of the system during running process,and affect the stability and safety of the maglev vehicle.Firstly,the two-dimensional axisymmetric HTS bulk simulation model is built,and the AC loss of the bulk superconductor under different magnetic fields is simulated.After that,the AC loss of maglev vehicle under magnetic field disturbance is studied experimentally.The experimental results show that the AC loss of maglev increases with the magnetic field gradient and running speed,which is similar to the magnetic resistance.After the reliability of the simulation model is verified,the finite element method(FEM)model is used to expand the research on the AC loss characteristics.The research results can provide reference for the AC loss of HTS Maglev vehicle,and the FEM model is conducive to the research of AC loss.To sum up,this paper makes a comprehensive study on the magnetic resistance and AC loss of HTS Maglev train from the perspectives of theory,simulation and experiment.The research results have a strong guiding significance for the construction of a new superconducting maglev transportation system in the future,and also have an important reference for improving the operation stability of the existing maglev train and reducing its energy consumption. |
PDF Full Text Request