Dynamic Characteristics Of Magnetic Resistance Of High Temperature Superconducting Maglev System Under Higu-speed Motion In Large Fluctuating Magnetic Field

Since the discovery of high-temperature superconductor with critical temperature higher than 77 K(the temperature of liquid nitrogen),high-temperature superconducting(HTS)technology has been used in many different fields.HTS maglev train composed of HTS bulks and permanent magnetic guideway(PMG)is one of the most important applications.Up to now,several hundred-meter-long test lines and manned magnetic levitation trains proportional to the actual application size have been successfully built,and the highest running speed of a test vehicle has reached 160 km/h.However,despite the potential of high speed and other advantages of HTS-Maglev technology,there are still many challenges in further improving its running speed,in which the stability of maglev train during high-speed operation is one of the key scientific and technical problems.In addition,energy consumption and instability caused by various resistances should also be studied to further optimize the system.The experiments were carried by simulating the high-speed dynamic characteristics of HTS maglev vehicle with a rotating platform system.The magnetic field gradient along the PMG was enlarged by the covering of iron sheets with different thickness.The dynamic characteristics of magnetic resistance and the stability of HTS-Maglev system under different field cooling height,external magnetic field variation amplitude and frequency were analyzed.The correctness of these conclusions was verified by numerical simulation.Firstly,this paper introduces the research background of HTS-Maglev technology,the development history of superconductors,the basic characteristics of superconductors and the existing key problems of HTS-Maglev vehicle,and puts forward the main ideas and implementation scheme.Then,the overall structure of the experimental platform is described,the function and using method of the measuring instruments used in the experiment are introduced in detail,and the specific operation process and matters needing attention are noted.Nextly,the dynamic characteristics of magnetic resistance of HTS-Maglev system under different external magnetic field intensity,field cooling height and changing frequency are analyzed in time domain.The influence of the variation amplitude and frequency of the external magnetic field on the magnetic resistance is qualitatively analyzed from the whole motion process including acceleration,uniform speed and deceleration.And the stability of the HTS-Maglev system under different motion states is analyzed from the detail waveform of the magnetic resistance.Then,frequency domain analysis and chaos analysis are carried out on the dynamic characteristics of magnetic resistance,and the variation trend of frequency band width and power spectral density of the HTS-Maglev system under different external magnetic field is studied.The intuitive method and Lyapunov numerical calculation method are used to judge whether the nonlinear dynamical system enters the chaotic state.The influence of the variation amplitude and frequency of the external magnetic field on the stability of the system was studied quantitatively.Finally,the dynamic characteristics of the HTS-Maglev system were simulated based on matlab,and the vibration status of the HTS under different external magnetic field variation amplitude and frequency was analyzed,which verified the correctness of dynamic characteristics analysis of magnetic resistance.