Maglev Charactericstics Of HTS YBCO Bulk Above Permanent Magnet Guideway Under External Disturbances

The first man-loading high temperature superconducting (HTS) maglev test vehicle in the world was tested successfully on Dec. 31, 2000 in Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Consequently, in 2004, Germany and Russia developed HTS maglev test vehicles. The HTS maglev vehicle, along with its distinctive and advantageous characteristics, shows a good prospect and has great potential economically in the transportation field. With further research on the characteristics of the HTS maglev vehicle, this technology is coming closer and closer to be a reality. Therefore, practical research on the HTS maglev vehicle technology is necessary. This dissertation mainly studied the maglev characteristics of HTS bulk samples above a permanent magnet guideway (PMG) under three external disturbances both experimentally and computationally. The experimental data were obtained from the platforms that were constructed with the HTS maglev launch prototype system and the HTS maglev measurement system SCML-2 developed by the National High Technology Research and Development Program ("863" Program) of China. The maglev characteristics of the YBCO bulk were studied above the PMG with different ramp angles, under loads, and under the presence of vibrations. Computationally, according to the flux flow and creep model, the author adopted numerical method to calculate the levitation force of the HTS bulk above PMG, and concurrently verified experimentally to confirm the validity of the numerical method. Results showed that this method was reliable. In addition, the variation of the current density distribution was analyzed when the bulk traveled above the PMG. Based on the results, relevant calculations were carried out with the same numerical method.Firstly, the work in this dissertation experimentally investigated the characteristics of the HTS maglev on the PMG with ramp angles. The research scheme was obtained through simplified analysis for the ramp climbing process of the HTS maglev vehicle, and then carried out during the ramp climbing experiment. The simulation experiment was also carried out aiming at the variation of HTS maglev characteristic parameters (levitation force, guidance force, stiffness of levitation force, levitation gap, etc). No such research has been reported until now.Secondly, the maglev characteristics of the HTS maglev vehicle under loads (drift of the levitation gap, relaxation of the levitation force) were studied. Studies on the drifts of the levitation gap under load, unloaded, and loaded again were carried out. To test the validity of the numerical calculation, the study on the levitation force relaxation of the HTS maglev system under load was carried out experimentally with the HTS maglev measurement system. The results of the experiment showed consistency with the calculation. Based on this, the levitation force relaxation under load and unload process was calculated by this numerical method, and a method which can be employed to decrease the levitation force relaxation was presented. The reports about the research on the characteristics of HTS maglev vehicle under load have not been found.Thirdly, the research on the drift of the levitation gap of the vehicle body, which was under the vibration caused by the inhomogeneity of the applied magnetic field, was carried out when the vehicle was in the low-speed running process. No such research has been reported until now. In order to study the influence on the maglev characteristics caused by vibrations, investigations on the variation of the levitation force and current density distribution under vertical and horizontal vibrations were carried out. Reports about the study on the effects of horizontal vibration on maglev vehicles have not been found.Lastly, optimization methods of the HTS maglev performance under external disturbances were discussed, including improving the levitation force density, adjusting levitation force hysteretic behavior and reducing levitation force relaxation.The work in this dissertation establishes the foundations for the gradeability and loading capacity of the HTS maglev vehicle; at the same time, it help the study of stability and reliability of the HTS maglev vehicle as well as provide a theoretical basis for the optimization design of the HTS maglev vehicle system.