Evaluation of two commercial finite element packages for calculating AC losses in 2-D high temperature superconducting strips

Sirois, Frédéric; Dione, Mouhamadou; Roy, F.; Grilli, Francesco; Dutoit, B.

doi:10.1088/1742-6596/97/1/012030

Cited by 21 publications

(14 citation statements)

References 10 publications

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“…There exist a number of different numerical techniques that have been applied variously to the modelling of superconducting materials [30,46], including the finite difference (FD) method [47], the combined sand-pile/Biot-Savart method [48][49][50][51], the Fourier Transform method [29], minimisation or variational techniques [52][53][54][55][56][57][58] and the finite element method (FEM). In general, FEM techniques are the most commonly used and developed methods, and these can be applied to superconducting material problems using a variety of formulations [30,59,60]: namely the A-V [61][62][63], T-Ω [64][65][66], H [67][68][69][70][71][72][73][74][75][76][77][78] and E [59,[79][80][81] formulations, and Campbell's equation [63,82]. Maxwell's equations can be written in each of these formulations and these formulations are equivalent in principle, but the solutions of the corresponding partial differential equations (PDEs) can be very different …”

Section: Numerical Techniquesmentioning

confidence: 99%

Modelling of bulk superconductor magnetization

Ainslie

Fujishiro

2015

Supercond. Sci. Technol.

181

166

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This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB 2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialisation stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarised with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet-superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets (TFMs). Finally, the use of hollow bulk cylinders/tubes for shielding is analysed.

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Section: Numerical Techniquesmentioning

confidence: 99%

Modelling of bulk superconductor magnetization

Ainslie

Fujishiro

2015

Supercond. Sci. Technol.

181

166

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“…In this section, the influence of inhomogeneities on trapped field is investigated qualitatively using a three-dimensional (3D) finite-element model. The finite-element model is based on the Hformulation, which has been applied variously to analysing high temperature superconductors for over a decade [12][13][14][15][16][17][18][19][20][21][22], and is implemented using COMSOL Multiphysics version 4.3a [23]. To model the electromagnetic and thermal properties of a bulk superconductor in 3D, we have extended previous models of HTS coated conductors [17][18][19]21] and drawn additional inspiration from references [20,24,25].…”

Section: Modelling Inhomogeneous Behaviourmentioning

confidence: 99%

Modelling and comparison of trapped fields in (RE)BCO bulk superconductors for activation using pulsed field magnetization

Ainslie

Fujishiro

Ujiie

et al. 2014

Supercond. Sci. Technol.

122

143

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The ability to generate a permanent, stable magnetic field unsupported by an electromotive force is fundamental to a variety of engineering applications. Bulk high temperature superconducting (HTS) materials can trap magnetic fields of magnitude over ten times higher than the maximum field produced by conventional magnets, which is limited practically to rather less than 2 T. In this paper, two large c-axis oriented, single-grain YBCO and GdBCO bulk superconductors are magnetised by the pulsed field magnetisation (PFM) technique at temperatures of 40 and 65 K and the characteristics of the resulting trapped field profile are investigated with a view of magnetising such samples as trapped field magnets (TFMs) in-situ inside a trapped flux-type superconducting electric machine. A comparison is made between the temperatures at which the pulsed magnetic field is applied and the results have strong implications for the optimum operating temperature for TFMs in trapped fluxtype superconducting electric machines. The effects of inhomogeneities, which occur during the growth process of single-grain bulk superconductors, on the trapped field and maximum temperature rise in the sample are modelled numerically using a 3D finite-element model based on the H-formulation and implemented in Comsol Multiphysics 4.3a. The results agree qualitatively with the observed experimental results, in that inhomogeneities act to distort the trapped field profile and reduce the magnitude of the trapped field due to localised heating within the sample and preferential movement and pinning of flux lines around the growth section regions (GSRs) and growth sector boundaries (GSBs), respectively. The modelling framework will allow further investigation of various inhomogeneities that arise during the processing of (RE)BCO bulk superconductors, including inhomogeneous J c distributions and the presence of current-limiting grain boundaries and cracks, and it can be used to assist optimisation of processing and PFM techniques for practical bulk superconductor applications.

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“…Electromagnetic models of HTS devices using the Finite Element Method (FEM) have already been tested successfully by other teams, especially for AC losses computations [4]- [7], but meshing (high aspect ratio of coated conductors layers) as well as nonlinear convergence issues make these methods quite challenging to use [8]. We propose a more flexible approach based on a Volume Integral Formulation associated to the Partial Element Equivalent Circuit (PEEC) method [9] and adapted to 2D axisymmetric problems, whose main advantage is to require a mesh for active regions only, particularly convenient for RE-BCO coil modeling as the active regions are only defined by the very thin superconducting layer (as long as the tape is not transiting, otherwise all conducting layers should be considered too, as well as a thermal coupling).…”

Section: Volume Integral Formulationmentioning

confidence: 99%