Study Of Levitation Performance Of High Temperature Superconducting Magnetic Levitation System At Different Temperatures

High-temperature superconductor magletic levitation system is a self-stable levitation system. The stable levitation results from electromagnetic interaction between external magnetic field and high-temperature superconductor (HTSC). Because HTSC with high critical temperature can operate at liquid nitrogen temperatures, so magnetic levitation technology based on HTSC has been attracting more and more attentions on the academic field and the engineering field. At present, the high-temperature superconducting (HTS) magnetic levitation (Maglev) system is mainly divided into two categories: one is the axisymmetric HTS Maglev system and the other is the HTS Maglev system with translational symmetry. But more research is focused on the axisymmetric HTS Maglev system rather than the system with translational symmetry. Moreover, study on the performance of the Maglev system at the temperature of 77 K is much more than that of the system at the other temperatures. Especially, the study of levitation performance of HTS Maglev system in the condition of deep cool is little. As well known, levitation characteristics of the HTS Maglev system with translational symmetry at different temperatures are vital importance for the engineering application. It is because the HTS Maglev system with translational symmetry may exist a higher efficiency at lower temperature, and thus the best operating temperature of the system may be found. So this thesis focuses on the levitation performances of the HTS Maglev system with translational symmetry at different temperatures whose aim was to further enhance and improve the performance of HTS Maglev system, promoting the process of practical applications of HTS Maglev vehicle and HTS Maglev launching.For the HTS Maglev system with translational symmetry, the system's performance is dependent on the distribution and magnitude of the permanent magnet guideway's (PMG) magnetic field. So optimizing PMG is a direct and effective approach to improve the levitation performance. A two-pole Halbach array's PMG is first proposed. The calculations show that Halbach PMG has a higher PM utilization than the present PMG. Then, the levitation force of bulk HTSCs with the present PMG and Halbach PMG are measured. The results show that at different levitation gaps, the force ratios based on the Halbach PMG are about 2-3 times larger than that on the present PMG, which greatly increases the load capability of the system. Therefore, both the numerical analysis and experimental results have confirmed that the Halbach PMG will further enhance the performance of the system. Based on the Halbach PMG, we further study the width ratios between HTSCs and PMG for making the better use of HTSCs. Some preliminary results are given. These results are important for further HTS Maglev system designs using Halbach PMG.The HTS Maglev low-temperature measurement platform was constructed. Using the measurement platform, the experiment was carried out in two different ways: the continuous and non-continuous test methords to study the influence on the levitation force of HTS bulks by different test model. And the relationship between the test methods mentioned above was analyzed for the sake of increasing the reliability for applications. Further more, the distribution of induced current in a ring-shape bulk was analyzed above the Halbach PMG under Bean model frame. The levitation performance of translational symmetry system at lower than 77K under circumstances including different field cooling heights (FCHs), working heights, the distribution and magnitude of the PMG's magnetic field was investigated. Therefore the factors influencing of the levitation performance of the system in the condition of deep cool are obtained. The hysteretic performance and stiffness of levitation force were studied at different temperatures. Moreover, with different running velocity, running time, round-trip running mode, the levitation force performance of the system with translational symmetry was studied at temperatures below 77 K. This is the first time to record the experimental datas of levitation performance of the system with translational symmetry in the condition of deep cool.Finally, using HTS Maglev low-temperature test platform, the levitation performances of the system with translational symmetry at temperatures above 77 K were studied for the system reliability in the applications...