Numerical Analysis of AC Loss Characteristics of YBCO Coated Conductors Arranged in Parallel

Ichiki, Y.; Ohsaki, Hiroyuki

doi:10.1109/tasc.2005.848246

Cited by 18 publications

(8 citation statements)

References 7 publications

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“…The result of the YBCO stack is much larger than that of the single conductor in the whole range of . The above results are consistent with Müller's analytical result and Ichiki and Ohsaki's numerical result [2], [3]. The significant increase in transport loss of the YBCO stack is due to the superposition of self magnetic field generated by the conductors composing the YBCO stack.…”

Section: B Transport Loss Without External Magnetic Fieldsupporting

confidence: 90%

Total AC Loss Characteristics in a Stacked YBCO Conductor

Jiang

Amemiya

Kakimoto³

et al. 2007

IEEE Trans. Appl. Supercond.

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Four 5 mm-wide YBCO conductors with identical critical current were assembled face to face to obtain a stacked YBCO conductor. The magnetization losses without transport current, the transport losses without external magnetic field, and the total AC losses of the stacked YBCO conductor as well as a single YBCO conductor carrying various transport currents in transverse magnetic fields with various orientations were measured. The difference between the AC loss characteristics of the stacked YBCO conductor and those of the single YBCO conductor was clarified.

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Section: B Transport Loss Without External Magnetic Fieldsupporting

confidence: 90%

Total AC Loss Characteristics in a Stacked YBCO Conductor

Jiang

Amemiya

Kakimoto³

et al. 2007

IEEE Trans. Appl. Supercond.

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“…If a parallel stack without transposition is connected together at both ends and energized with current, the conductors positioned outside carry more current than those positioned inside. This causes higher AC loss than a parallel stack where all the conductors carry the same current [20]. This explains why transport AC loss in 2G cables with the Roebel structure is reduced compared to cables without transposed stacks.…”

Section: Discussion On Transport Ac Loss In a Nine Strand Roebel Cablementioning

confidence: 99%

Transport AC loss characteristics of a nine strand YBCO Roebel cable

Jiang¹,

Badcock²,

Long³

et al. 2010

Supercond. Sci. Technol.

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Transport AC loss in a short length of 9/2 YBCO Roebel cable (nine 2 mm wide strands) is measured. The AC loss data are compared with those in a 5/2 YBCO Roebel cable (five 2 mm wide strands) as well as that in a single strand. All the strands composing the cables and the single strand are insulated and cut from the same stock material. The validity of the measurement method was reconfirmed by results at a range of frequencies. At a wide range of I t /I c , the normalized AC losses in the Roebel cable were around 6.2-6.7 times of those in the single strand. This is less than the nine times predicted for a tight bundle of nine conductors. The normalized transport AC losses in the 5/2 Roebel cable are much smaller than those in the 9/2 Roebel. This should be due to larger superposition of magnetic field in the 9/2 Roebel. The I c of the 9/2 and 5/2 Roebel cables is determined by serial connection of the strands. This eliminates the effect where differing resistances in the current terminations cause uneven current sharing between strands when the strands are connected in parallel.

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“…In this sense, the simulation of the electromagnetic behaviour of 2G-HTS coils presents serious challenges, especially in conditions where one needs to consider the in-field dependence of the critical current, Ic, this in terms of the direction and intensity of the magnetic field per coil-turn, as pointed out in early experiments measuring the magnetic field distribution and AC loss of HTS thin films in superconducting coils [25,26]. Nonetheless, regardless of the 2G-HTS tape being used, certain consensus has been reached in terms of describing the current-voltage characteristics of all type-II superconductors as a power law, V(I/Ic)n, with n≫1, which from the computational point of view renders the well-known form of the material law for the electric field, also called the E-J power law, boldE(J)=E0·boldJ/Jc·(|J|/Jc)n−1, which in a local but macroscopical approach allows solution of the Maxwell equations inside the superconducting domains within diverse mathematical formulations, for a large range of experimental measurements [16,23,27,28,29,30,31,32,33,34,35,36,37,38]. Here, Jc is the critical current density of the 2G-HTS tape defined within the standard electric field criterion E0 = 1 …”

Section: Introductionmentioning

confidence: 99%

How to Choose the Superconducting Material Law for the Modelling of 2G-HTS Coils

Robert

Fareed

2019

Materials

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In an attempt to unveil the impact of the material law selection on the numerical modelling and analysis of the electromagnetic properties of superconducting coils, in this paper we compare the four most common approaches to the E-J power laws that serve as a modelling tool for the conductivity properties of the second generation of high-temperature superconducting (2G-HTS) tapes. The material laws considered are: (i) the celebrated E-J critical-state like-model, with constant critical current density and no dependence with the magnetic field; (ii) the classical Kim’s model which introduces an isotropic dependence with the environment magnetic field; (iii) a semi-empirical Kim-like model with an orthonormal field dependence, J c ( B ) , widely used for the modelling of HTS thin films; and (iv) the experimentally measured E–J material law for SuperPower Inc. 2G-HTS tapes, which account for the magneto-angular anisotropy of the in-field critical current density J c ( B ; θ ) , with a derived function similar to Kim’s model but taking into account some microstructural parameters, such as the electron mass anisotropy ratio ( γ ) of the superconducting layer. Particular attention has been given to those physical quantities which within a macroscopic approach can be measured by well-established experimental setups, such as the measurement of the critical current density for each of the turns of the superconducting coil, the resulting distribution of magnetic field, and the curve of hysteretic losses for different amplitudes of an applied alternating transport current at self-field conditions. We demonstrate that although all these superconducting material laws are equally valid from a purely qualitative perspective, the critical state-like model is incapable of predicting the local variation of the critical current density across each of the turns of the superconducting coil, or its non-homogeneous distribution along the width of the superconducting tape. However, depending on the physical quantity of interest and the error tolerance allowed between the numerical predictions and the experimental measurements, in this paper decision criteria are established for different regimes of the applied current, where the suitability of one or another model could be ensured, regardless of whether the actual magneto angular anisotropy properties of the superconducting tape are known.

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Numerical Analysis of AC Loss Characteristics of YBCO Coated Conductors Arranged in Parallel

Cited by 18 publications

References 7 publications

Total AC Loss Characteristics in a Stacked YBCO Conductor

Total AC Loss Characteristics in a Stacked YBCO Conductor

Transport AC loss characteristics of a nine strand YBCO Roebel cable

How to Choose the Superconducting Material Law for the Modelling of 2G-HTS Coils

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