Dynamic Characteristics Of High Temperature Superconducting Magnetic Levitation System With Translational Symmetry

Owing to the intrinsic flux pinning inside the superconductor, bulk high temperature superconductor (HTSC) can stably levitate or suspend in a magnetic field. This novel and simple passive stable magnetic levitation yields the possible applications like the Maglev train, especially the successful development of the first man-loading high temperature superconducting (HTS) Maglev test vehicle in 2000. This HTS levitation system above infinitely long permanent magnetic guideway (PMG) is with translational symmetry. More research is focused on the cylindrical HTS magnetic levitation system rather than the system with translational symmetry. Moreover, study on the quasi-static characteristics is much more than that on dynamic characteristics. As well known, dynamic characteristics are of vital importance for the engineering application of the HTS Maglev train. So this thesis focuses on dynamic characteristics of the HTS Maglev system with translational symmetry.For its engineering application, vibrational measurements are made to discuss physical nature and effect on the dynamic motion of the HTS Maglev system with translational symmetry. Based on its two-dimensional dynamic model, the relationship between dynamic stiffness and static stiffness are studied as well as some important dynamic parameters like resonance frequency, dynamic stiffness and damping coefficient.The scaled HTS Maglev vehicle with 4:1 ratio to the real test vehicle is made and the dynamic parameters are measured with different field cooling height (FCH), working height and load weight. Base on the hysteretic performance of levitation force and the dynamic model, the free vibration response and levitation drift are further simulated in order to study stability of the HTS Maglev vehicle system. On the other hand, it presents dynamic characteristics and its motions with different moving velocity and different FCH. This is the first time to obtain the experimental results of running status of the HTS Maglev vehicle, which will be experimental evidence of the running performance of the future HTS Maglev train.Three methods are proposed to improve the dynamic characteristics of the HTS Maglev system. They are pre-loading, to introduce eddy damper and super-cooling. More investigations are given on effect of the first two methods as well as their application conditions.Moreover, it is found that to introduce HTS magnet is possible to realize the same stable levitation with the HTS levitation by the vibration measurement. Moreover, dynamic characteristic, levitation force and guidance force further show the feasibility of introducing HTS magnet to a stable HTS Maglev system. Besides the above three methods, this method is very helpful to improve dynamic characteristics of HTS Maglev system as well as stability.