AC Losses of Superconducting Racetrack Coil in Various Magnetic Conditions

Hong, Zhiyong; Yuan, Weijia; Ainslie, Mark; Yu, You‐Jun; Pei, Ruilin; Coombs, Tim

doi:10.1109/tasc.2010.2084065

Cited by 36 publications

(24 citation statements)

References 10 publications

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“…Also, it is worth mentioning that to the authors' knowledge most of the reported studies on superconducting racetrack coils 16,20,24,30 refer not only to perfectly wound magneto-isotropic coils, but for coils made of 12 mm wide tapes under particular transport current conditions aimed to assert specific experimental evidences. Therefore, none of the previous studies allow For completing the full hysteretic picture of the time-dependent current dynamics shown in Fig.…”

Section: Geometry Considerations and Modelling Strategymentioning

confidence: 99%

“…Attaining a clear understanding of the physical and designing parameters that might render to the minimization of AC losses in these systems is, by default, one of the most important subjects in the physics and engineering of applied superconductivity. [6][7][8][9][10][11][12] However, despite many experimental and theoretical studies have been performed on the AC losses of HTS racetrack coils, [13][14][15][16][17] these always assume that the coil is perfectly wound, neglecting thence any influence of a possible misalignment between the coil turns (tapes), a situation that is likely to happen either during the coil manufacturing, their assembling in practical applications, or even due to possible axial alterations caused by extrinsic magnetic, thermal, or mechanical pressure over the coil turns. In fact, despite than in the last two decades the applied superconductivity field has experienced a significant increase in the physical understanding of the local electromagnetic properties of type II superconductors, including the second generation of high temperature superconducting (2G-HTS) tapes, it is the high aspect ratio of the 2G-HTS tapes what from the computational perspective is still imposing significant challenges to understand their performance in practical superconducting machines.…”

Section: Introductionmentioning

confidence: 99%

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Local electromagnetic properties and hysteresis losses in uniformly and non-uniformly wound superconducting racetrack coils

Robert

Fareed

2019

Journal of Applied Physics

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A noteworthy physical dependence of the hysteresis losses with the axial winding misalignment of superconducting racetrack coils made with commercial Second Generation High Temperature Superconducting (2G-HTS) tapes is reported. A comprehensive study on the influence of the turn-to-turn misalignment factor on the local electromagnetic properties of individual turns, is presented by considering six different coil arrangements and ten amplitudes for the applied alternating transport current, I a , together with an experimentally determined function for the magnetoangular anisotropy properties of the critical current density, J c (B, θ), across the superconducting tape. It has been found that for moderate to low applied currents I a ≤ 0.6 I c0 , with I c0 the self-field critical current of individual tapes, the resulting hysteretic losses under extreme winding deformations can lead to an increase in the energy losses of up to 25% the losses generated by a perfectly wound coil. High level meshing considerations have been applied in order to get a realistic account of the local and global electromagnetic properties of racetrack coils, including a mapping of the flux front dynamics with well defined zones for the occurrence of magnetization currents, transport currents, and flux-free cores, what simultaneously has enabled an adequate resolution for determining the experimental conditions when turn-to-turn misalignments of the order of 20 µm-100 µm in a 20 turns 4 mm wide racetrack coil can lead not only to the increment of the AC losses but also to its reduction.In this sense, we shown that for transport current amplitudes I a > 0.7 I c0 , a slight reduction in the hysteresis losses can be achieved as a consequence of the winding displacement which is at the same time connected with the size reduction of the flux free core at the coil central turns. Our findings can be used as a practical benchmark to determine the relative losses for any 2G-HTS racetrack coil application, unveiling the physical fingerprints that possible coil winding misalignments could infer.

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Section: Geometry Considerations and Modelling Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Local electromagnetic properties and hysteresis losses in uniformly and non-uniformly wound superconducting racetrack coils

Robert

Fareed

2019

Journal of Applied Physics

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“…This creates an artificial spike of the dissipated power. Therefore we insert a waiting sequence T B of 2.29 s to allow for flux relaxation [20], [21] before starting the steady-state sequence T C .…”

Section: E Sequencementioning

confidence: 99%

AC Losses of a Grid-Connected Superconducting Wind Turbine Generator

Quéval

Ohsaki

2013

IEEE Trans. Appl. Supercond.

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We present a numerical method to estimate the steady-state AC losses of a superconducting wind turbine generator connected to the grid through its AC/DC/AC converter. We use a multiscale simulation with unidirectional couplings between a lumped-parameter wind energy conversion system model, a finite element machine model, and a finite element HTS tape model. The estimation include effects linked to the generator space harmonics, the exciter control, and the AC/DC/AC converter PWM and control. As the superconducting coil is made of several thousand of HTS tapes, we evaluate AC losses for a fraction of them and we interpolate the results to the others. The steady-state AC losses of a 10 MW class generator are estimated to be under 60 W.

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“…Recently, numerical approaches based on the material continuum models have received more attention in predicting AC loss [15][16][17][18][19][20][21][22][23][24][25][26][27]. Several numerical methods have been proposed to solve the Maxwell equations using the finite element method or the finite difference method [16,[28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

“…Several numerical methods have been proposed to solve the Maxwell equations using the finite element method or the finite difference method [16,[28][29][30][31][32]. Due to the advantages of H-formulation, it has become a powerful tool to study the superconductor's behaviors [15,21,[33][34][35][36]. Several numerical models are available for studying the behaviors subject to transport current or exposed to transverse magnetic field [15,27,31,37].…”

Section: Introductionmentioning

confidence: 99%