Entity

Time filter

Source Type


Ma G.-T.,Southwest Jiaotong University | Ma G.-T.,National Laboratory for Rail Transit | Wang J.-S.,Southwest Jiaotong University | Wang J.-S.,National Laboratory for Rail Transit | And 2 more authors.
Journal of Superconductivity and Novel Magnetism | Year: 2011

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. © 2010 Springer Science+Business Media, LLC. Source


Ma G.-T.,Southwest Jiaotong University | Ma G.-T.,National Laboratory for Rail Transit | Wang J.-S.,National Laboratory for Rail Transit | Wang J.-S.,Southwest Jiaotong University | And 2 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2010

In this paper, the 3-D model proposed in Part I of this study is verified in detail on the basis of a levitation/suspension system composed of a rectangular single-domain Y-Ba-Cu-O and a cylindrical Nd-Fe-B magnet or a permanent magnet guideway (PMG) assembled by the Nd-Fe-B magnets. The magnetic forces along the vertical direction perpendicular or the transverse direction parallel to the surface of the PMG (or magnet) were calculated and compared well with the measured data under vertical and transverse displacements. The computed results of the induced current distribution within the Y-Ba-Cu-O domain, as well as the magnetic field profiles in the Y-Ba-Cu-O and its vicinal region, were also presented and discussed. © 2006 IEEE. Source


Ma G.-T.,Southwest Jiaotong University | Ma G.-T.,National Laboratory for Rail Transit | Wang J.-S.,National Laboratory for Rail Transit | Wang J.-S.,Southwest Jiaotong University | And 2 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2010

A magnetic levitation technique with high-Tc superconductor (HTS) has received significant interest for a wide range of applications after its discovery due to its unique inherent stability, which gives a fundamental significance to evaluate the HTS magnetic levitation in both experiment and calculation. To numerically investigate the HTS magnetic levitation, a 3-D model describing the electromagnetic property of the HTS, including its anisotropic behavior, was established by incorporating the current vector potential and Helmholtz's theorem. In addition to the commonly considered nonlinear E-J characteristic in the reported calculation, we introduce an elliptical model to formulate the angular dependence of the critical current density Jc resulting from the anisotropic behavior of the HTS. To numerically resolve the governing equations of the 3-D model, Galerkin's finite-element method and the Crank-Nicolson-θ method were employed to discretize the governing equations in space and time domains, respectively. The obtained algebraic equations were firstly linearized by the NewtonRaphson method, and then an extended format of the incomplete Cholesky-conjugate gradient method was applied to solve the linear algebraic equations. The 3-D model was implemented by a self-written numerical program based on a VC++ platform to calculate the magnetic force of a bulk HTS exposed to applied field generated by a permanent magnet guideway (PMG) assembled by the Nd-Fe-B magnets. In this paper, we present the numerical results of the levitation force of a moving bulk HTS above the PMG with different mesh densities and number of time steps. This presents a preliminary validation of the 3-D model proposed in this paper. © 2006 IEEE. Source


Wang J.,Applied Superconductivity Laboratory ASCLab | Wang J.,National Laboratory for Rail Transit | Wang S.,Applied Superconductivity Laboratory ASCLab | Wang S.,National Laboratory for Rail Transit | And 16 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2011

This year marks the tenth anniversary of the first man-loading high temperature superconducting (HTS) maglev test vehicle "Century" in the world. This report summarizes development advances of major topics related to the HTS maglev vehicle at the Applied Superconductivity Laboratory (ASCLab) at Southwest Jiaotong University (SWJTU). The HTS Maglev measurement systems are described, including the HTS maglev dynamic test system capable of speeds up to 300 km/h. Through these measurement systems, many problems related to the HTS maglev have been studied such as system optimization, stability control, influence from ramp angles, influence from AC field, and investigation of the system's properties at temperatures lower than 77 K. Apart from experimental studies, the 3-D model of the HTS maglev was constructed via two different methods to simulate the Maglev's behavior. © 2011 IEEE. Source


Lin Q.,Southwest Jiaotong University | Jiang D.,Southwest Jiaotong University | Wang J.,Southwest Jiaotong University | Wang J.,National Laboratory for Rail Transit | And 10 more authors.
Physics Procedia | Year: 2012

A measurement testing setup of the characteristic properties for high temperature superconducting bearing (HTSB) systems is introduced in this paper. The equipment setup can measure the radial and axial forces, temperature, oscillation and rotary speed of the HTSB simultaneously, so the relation between these properties can be investigated. For example, the decrease of the radial and axial forces, and the increase of the temperature can be measured and analyzed during different rotary speeds of the permanent magnetic rotor. The measurement ranges for the radial and axial force will reach 5 kN and 10 kN. The temperature of the superconductors in HTSB can then be controlled by adjusting the air press inside the dewar which is an easier method compared with a cryocooler. © 2012 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Guest Editors. Source

Discover hidden collaborations