Experimental and numerical study of a YBCO pancake coil with a magnetic substrate

Zhang, Min; Kvitkovič, J.; Pamidi, Sastry; Coombs, Tim

doi:10.1088/0953-2048/25/12/125020

Cited by 62 publications

(46 citation statements)

References 25 publications

(31 reference statements)

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“…The numerical model developed here combines the electromagnetic equations governing the behaviour of the superconductor based on the 2D axisymmetric H-formulation [39][40][41][42] with the same modifications made to include magnetic subdomains with a relative permeability μ r (H) as described in [25,26,43,44].…”

Section: Modelling Frameworkmentioning

confidence: 99%

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Philippe

Ainslie

Wera

et al. 2015

Supercond. Sci. Technol.

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Bulk, high temperature superconductors have significant potential for use as powerful permanent magnets in a variety of practical applications due to their ability to trap record magnetic fields. In this paper, soft ferromagnetic sections are combined with a bulk, large grain Y-Ba-Cu-O (YBCO) high temperature superconductor to form superconductor/ferromagnet (SC/FM) hybrid structures. We study how the ferromagnetic sections influence the shape of the profile of the trapped magnetic induction at the surface of each structure and report the surface magnetic flux density measured by Hall probe mapping. These configurations have been modelled using a 2D axisymmetric finite element method based on the H-formulation and the results show excellent qualitative and quantitative agreement with the experimental measurements. The model has also been used to study the magnetic flux distribution and predict the behaviour for other constitutive laws and geometries. The results show that the ferromagnetic material acts as a magnetic shield, but the flux density and its gradient are enhanced on the face opposite to the ferromagnet. The thickness and saturation magnetization of the ferromagnetic material are important and a characteristic ferromagnet thickness d* is derived: below d*, saturation of the ferromagnet occurs, and above d*, a weak thicknessdependence is observed. The influence of the ferromagnet is observed even if its saturation magnetization is lower than the trapped flux density of the superconductor. Conversely, thin ferromagnetic discs can be driven to full saturation even though the outer magnetic field is much smaller than their saturation magnetization. [5,6]) is well beyond the saturation magnetization of conventional ferromagnets. This makes them extremely promising as a competing technology for traditional permanent magnets in various applications [7][8][9][10]. The combination of ferromagnetic and superconducting materials can enhance the performance of the superconductor [11,12] and even lead to new applications [13]. Large grain, bulk superconductors are often used in applications that incorporate ferromagnetic materials, such as in motors and generators [14,15]. Ferromagnets can also increase the force in levitation systems [16,17] and close the magnetic circuit, which improves the available flux produced by bulk superconductors [18]. Similarly, ferromagnetic materials are used as sheaths around multifilament wires and tapes [19,20] or as magnetic flux diverters to modify the flux distribution around tapes and superconducting coil magnets [21][22][23][24][25][26][27][28]; thereby improving their electrical properties (i.e. increasing the critical current and reducing AC losses).

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Section: Modelling Frameworkmentioning

confidence: 99%

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Philippe

Ainslie

Wera

et al. 2015

Supercond. Sci. Technol.

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“…H-formulation of 2D axial symmetry is used to calculate the ac loss after the FEM model is built in COMSOL [6]. The magnetic field can be expressed as…”

Section: B Calculation Of Ac Loss Of Hts Windingsmentioning

confidence: 99%

Design of Superconductivity Windings of a 35-kV/3.5-MVA Single-Phase HTS-Controllable Reactor

Shen

Tang

Wang

et al. 2015

IEEE Trans. Appl. Supercond.

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In order to compensate flexibly reactive power, it is necessary to develop a controllable reactor in long-distance and ultrahigh-voltage system. High-temperature superconductivitycontrollable reactor (HTS-CR) is a potential equipment in power system. A 35-kV/3.5-MVA single-phase HTS-CR is being developed. The HTS windings of the HTS-CR are made of double pancakes that are wound with HTS tapes connected in parallel. The relationship between the number of double pancakes and the number of HTS tapes, which has great effect on the current of each HTS tape, is studied. Furthermore, the solution that reduces the ac loss of the HTS winding is also investigated, which discloses the optimized design parameters and the calculation results of the HTS windings. The study here is believed to provide some references for developing HTS-CR with larger capacity in the future.

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“…In the past ten years, the finite element method (FEM) has become the dominated method to solve the electromagnetic behavior and AC loss in HTSs due to the necessity of considering highly nonlinear E-J relationship, complex geometries and complicated electromagnetic circumstances [9][10][11][12][13][14]. Recently, the FEM models based on the H-formulation have been intensively developed to solve a variety of geometries for practical applications, such as bulk superconductors, coated conductors, Roebel cables and coils [4,[15][16][17][18][19][20][21]. The simulations results agree well with the analytical and experimental results.…”

Section: Introductionmentioning

confidence: 99%

“…When the magnetic field dependent permeability and ferromagnetic loss of the magnetic substrate were taken into account, a new FEM model using the H-formulation was proposed to compute the electromagnetic characteristics and AC losses in YBCO tapes with magnetic substrates by Nguyen et al [25]. Based on this model, Zhang and colleagues [20,21] improved their pancake coil model [18] to study the pancake coil with a magnetic substrate later. In addition, Krüger et al [26] also built an H-formulation-based model to reproduce the experimental results and predict that soft ferromagnetic materials have the potential to significantly reduce hysteretic losses in HTS coated conductors.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations of electromagnetic behavior and AC loss in rectangular bulk superconductor with an elliptical flaw under AC magnetic fields

Xia

Zhou

2015

Cryogenics

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Experimental and numerical study of a YBCO pancake coil with a magnetic substrate

Cited by 62 publications

References 25 publications

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

Design of Superconductivity Windings of a 35-kV/3.5-MVA Single-Phase HTS-Controllable Reactor

Numerical simulations of electromagnetic behavior and AC loss in rectangular bulk superconductor with an elliptical flaw under AC magnetic fields

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