Finite element method analysis of the coupling effect between superconducting filaments of different aspect ratio

295

263

Numerical modeling of superconductors is widely recognized as a powerful tool for interpreting experimental results, understanding physical mechanisms and predicting the performance of high-temperature superconductor (HTS) tapes, wires and devices. This is especially true for ac loss calculation, since a sufficiently low ac loss value is imperative to make these materials attractive for commercialization. In recent years, a large variety of numerical models, based on different techniques and implementations, have been proposed by researchers around the world, with the purpose of being able to estimate ac losses in HTSs quickly and accurately. This article presents a literature review of the methods for computing ac losses in HTS tapes, wires and devices. Technical superconductors have a relatively complex geometry (filaments, which might be twisted or transposed, or layers) and consist of different materials. As a result, different loss contributions exist. In this paper, we describe the ways of computing such loss contributions, which include hysteresis losses, eddy current losses, coupling losses, and losses in ferromagnetic materials. We also provide an estimation of the losses occurring in a variety of power applications.

Section: A Simulating Filament-coupling Effectsmentioning

confidence: 99%

Computation of Losses in HTS Under the Action of Varying Magnetic Fields and Currents

Grilli

Pardo

Stenvall

et al. 2014

295

263

“…A more detailed investigation (including a comparison with some results predicted by analytical models) of the coupling effect between filaments of different aspect ratio, with emphasis on the underlying physical phenomena, can be found in [17].…”

Section: B Existence Of Coupling Currents In 3-d Simulationsmentioning

confidence: 99%

Finite-Element Method Modeling of Superconductors: From 2-D to 3-D

Grilli

Stavrev

Floch

et al. 2005

107

A three-dimensional (3-D) numerical modeling technique for solving problems involving superconducting materials is presented. The model is implemented in finite-element method software and is based on a recently developed 3-D formulation for general electromagnetic problems with solid conductors. It has been adapted for modeling of superconductors with nonlinear resistivity in 3-D, characterized by a power-law relation. It has first been compared with an existing and verified two-dimensional (2-D) model: Compared are the current density distribution inside the conductors and the self-field ac losses for different applied transport currents. Second, the model has been tested for computing the current distribution with typical 3-D geometries, such as corner-shaped and twisted superconductors. Finally, it has been used with two superconducting filaments in the presence of external magnetic field for verifying the existence of coupling currents. This effect deals with the finite length of the conductors and cannot be taken into account by 2-D models.

“…Many models based on different commercial FEM packages have been proposed to solve the critical state in superconductivity [6]- [8]. In this paper a general method is proposed to solve the critical state in superconductivity in 2D by utilizing the FEM II.…”

Section: Introductionmentioning

confidence: 99%

“…Since only has the component in z-direction, Ampere's law in this case is expressed as: (8) Substitution of (8) and (4) into (3) gives two coupled equations:…”

Section: Introductionmentioning

confidence: 99%

Computer Modeling of Magnetisation in High Temperature Bulk Superconductors

Hong

Campbell

Coombs

2007

A numerical method is proposed to analyse the electromagnetic behavior of systems including high-temperature superconductors (HTSC) in time-varying external fields. The E-J constitutive law together with an H-formulation is used to calculate the current distribution then the magnetisation hysteresis loop of the superconductor can be obtained. This numerical method is adapted to commercial finite element software to solve the partial differential equations time dependently and is able to give accurate results to many problems in complex geometries.Index Terms-Critical state, finite element method, high temperature superconductor, magnetic hysteresis loop.