Influence Of Magnetic Field Fluctuation On Suspension Characteristics Of High Temperature Superconducting Maglev System

With the rapid development of economic circles,urbanization as well as people's constant attention to environmental protection,traditional means of transportation which pollute the environment and jam the road are being replaced.The extensive development of electrified transportation has become the mainstream of the current era.As a new type of electrified transportation,maglev transportation has become the sixth kind of human traffic and has received special attention.Due to low energy consumption,low noise,safety and comfort,the high-temperature superconducting(HTS)magnetic levitation vehicle,which is based on HTS magnetic levitation technology,has become a hot spot for people to pursue.Exploring the changes in the operating status of the maglev vehicle by some experimental equipment and methods will be helpful to advance the development of HTS Maglev vehicle in practical application.In this paper,the existing HTS magnetic levitation simulation operating platform in the laboratory is fully utilized,and the principle of relative motion and the idea of straightening the curvature are used to explore the variation of the levitation force of the high-temperature superconductor bulk under the fluctuating magnetic field conditions.By adding some iron pieces,a strong magnetic field fluctuation is generated above the circular permanent magnet track,so a rectangular wave alternating magnetic field under different conditions is generated during the operation of the platform.The alternating magnetic field is used to study the variation characteristics of the levitation force of HTS bulk under different conditions.First of all,this paper introduces the development of superconductor and superconducting theory,and describes the critical parameters,magnetic flux pinning,flux movement and AC loss of superconductors.Then,the principle of HTS maglev is introduced,and the development of HTS maglev vehicle is focused.The research status of HTS magnetic levitation characteristics under fluctuating magnetic field is also described.Then,the test platform and test method are mainly introduced.The rotating permanent magnetic track on the test platform is described.The magnetic wave simulator and the HTS maglev device have been constructed,and the system data acquisition equipment is briefly described.After the introduction of the test platform,the experimental methods involved in this paper are explained.Then,the effect of the superimposed iron on the static suspension characteristics of HTS bulk is studied.The effect of superimposed iron on magnetic field distribution of per-manent magnetic track is first studied.then,the effects of the working height,the field cooling height,the working position and the thickness of the iron sheet on the static levitation force and relaxation characteristics of HTS bulk are investigated by comparing the conditions between the non-iron sheet and the superimposed iron sheet.Then,the levitation characteristics of HTS bulk under fluctuating external field are studied.In this part,the variation of the levitation force of HTS bulk under the process of acceleration and deceleration,the uniform process,different field cooling height and the amplitude of rectangular wave magnetic field are studied by the magnetic field fluctuation of the permanent magnet track and the rectangular wave magnetic field caused by the iron sheet.The formation mechanism of the wave field and the variation of the superconducting levitation force are also analyzed.Finally,based on the previous experiment,the effect of the cooling position,the running speed and the thickness of the iron sheet on the attenuation of levitation force before and after the operation of the HTS Maglev vehicle is studied under the field cooling condition and the zero field cold condition by increasing the running time of the annular track with the iron sheet.