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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.


Yen F.,Southwest Jiaotong University | Yen F.,National Laboratory for Rail Transit | Yen F.,Traction Power State Key Laboratory | Lin Q.,Southwest Jiaotong University | And 15 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2012

The critical current density of optimally doped bulk YBCO superconductor has been found to increase with the application of external hydrostatic pressure. This paper reports the transport measurements of the critical current (I c) of YBCO in the form of a coated conductor (CC) wire under hydrostatic pressure up to 0.24 GPa at 77 K. No noticeable change was observed in both the I c and n-value of the CC sample in the studied pressure range. Two possible scenarios are discussed to explain the observed effect. © 2012 IEEE.


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.


Yen F.,Southwest Jiaotong University | Yen F.,Traction Power State Key Laboratory | Yen F.,National Laboratory for Rail Transit | Li J.,Southwest Jiaotong University | And 17 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2011

A method to transport up to 180 A of current into the sample space of a pressure cell without causing thermal instabilities at 77 K was developed in order to study the critical current Ic of samples of first-generation Bi-2223 superconducting wire at different hydrostatic pressures. Ic was found to linearly decrease with increasing application of external pressure and was found to be irreversible upon release of pressure. The n-value of the voltage-current curves at different pressure was also found to systematically decrease. The decrease in Ic and the irreversibility effect is attributed to the deformation of the filamentary walls of the wire. © 2006 IEEE.


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.


Yen F.,Southwest Jiaotong University | Yen F.,National Laboratory for Rail Transit | Li J.,Southwest Jiaotong University | Li J.,National Laboratory for Rail Transit | And 12 more authors.
Superconductor Science and Technology | Year: 2010

Thrust measurements were performed on a coil made of a YBa 2Cu3O7-δ coated conductor acting as the excitation system of a single-sided linear synchronous motor. The superconducting coil was a single pancake in the shape of a racetrack with 100 turns, the width and effective lengths were 42 mm and 84 mm, respectively. The stator was made of conventional copper wire. At 77 K and a gap of 10 mm,with an operating direct current of IDC = 30 A for the superconducting coil and alternating current of IAC = 9 A for the stator coils, a thrust of 24 N was achieved. With addition of an iron core, thrust was increased by 49%. With addition of an iron back-plate, thrust was increased by 70%. © 2010 IOP Publishing Ltd.


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.


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.

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