HTS Maglev Systems Research Articles

Levitation Performance of a Magnetized Bulk YBCO With Different Demagnetization Processes

The magnetized bulk high- superconductor (MBSCM) can provide dramatic improvements towards the levitation performance of HTS Maglev systems if sufficient and suitable magnetic excitation methods are employed. In the field-cooling excitation mode, the demagnetization process greatly influences the levitation performance of the MBSCM in some special operation modes. A difference in the levitation performance was observed from experimental tests under different demagnetization field strengths and rates. Simulation based on finite element method was used to calculate the temperature rise within the MBSCM during the studied demagnetization process. With experimental results and analyses, an optimal demagnetization process for the MBSCM for engineering applications was derived.

Numerical Study of the Speed-Related Behavior of the Magnetic Force in the HTS Maglev System Based on a 3-D Model

Based on the 3-D model, we recently proposed to investigate numerically the performance of the HTS maglev system. The speed-related behavior of this kind of maglev system is further studied in this article. The 3-D model is firstly briefly introduced: the 3-D governing equations are established with current vector potential (T) as the state variable, and the special anisotropic behavior and the nonlinear E–J characteristic of the HTS were taken into account by an elliptical model and power-law model, respectively. Using a translational symmetry levitation system, which is composed of a rectangular HTS and a permanent magnet guideway (PMG) as an example, the speed-related behavior of the magnetic force in three different cases—i.e., the levitation force (LF) versus gap relation under the vertical movement, the time evolution of the LF, the guidance force (GF) versus lateral displacement relation under the transverse movement—are investigated. The result indicates that, with the increase of the speed, both the LF and GF increase but the rate of increase is reduced and finally saturates when the speed is large enough. We also find that the commonly used speed of 1 mm/s to investigate the magnetic force of the bulk HTS in the experiment is reasonable because both the LF and GF tend to saturate at this speed. For the time evolution study of the LF, although the peak value of the LF is largest when the speed is largest, the LF decay in the relaxed process is most serious, and consequently the final LF at different speeds is almost identical after relaxation. Therefore, the magnetic force cannot be enhanced by simply increasing the speed in the practical application.

Applications of YBCO melt textured bulks in Maglev technology

In this paper we report the present status and progress of HTS Maglev project undertaken at the Southwest Jiaotong University. The efforts and results towards solving the material-related issues in HTS Maglev system are emphasized, including the levitation and guidance forces, the magnetic and thermal stabilities related to the ac loss of YBCO superconducting material during a high speed movement, and the low stiffness of HTS Maglev system.

Magnetic levitation/suspension system by high-temperature superconducting materials

Recently, with the advance of materials processing techniques, such as top-seeding and melt-texturing (TSMT) method, very large single-grained Y-Ba-Cu-O (YBCO) samples up to several centimeters in diameter can be produced. Each sample is capable of levitating over kilograms of weight. A HTS magnetic levitation (MagLev) transportation prototype has been constructed at National Cheng-Kung University (NCKU) to validate the concept of HTS-MagLev system based on Meissner effect. This HTS-MagLev is an inherent stable levitation system, unlike traditional MagLev system that requires sensors and feedback circuits to dynamically adjust its unstable levitation position. In this report, the results of various magnetic levitation parameters, such as different permanent magnet configurations, relative levitation stability, levitation force, etc., as well as magnetic field intensity and distribution will be discussed.