Transport Loss Characteristics of the Bi-2223 Tapes in an External AC Magnetic Field

Ryu, K.; Song, Han Jung; Kim, H.J.; Seong, K.C.

doi:10.1109/tasc.2006.871306

Cited by 11 publications

(6 citation statements)

References 7 publications

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“…Equation 5 has been shown to provide close agreement to experimental values obtained in parallel applied fields for Bi-2223/Ag wire [21]. There have also been some previous experimental studies of both Bi-2223/Ag wires [21,22] and coated conductors [23,24] in perpendicular magnetic field. However, attempts to adapt equation (5) to the perpendicular field data have not provided close agreement.…”

Section: Introductionsupporting

confidence: 74%

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Jiang¹,

Toyomoto²,

Amemiya³

et al. 2021

Preprint

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Superconducting high-Tc coated conductor (CC) wires comprise a ceramic thin film with a large aspect ratio. This geometry can lead to significant dissipative losses when exposed to an alternating magnetic field. Here we report experimental measurements of the 'dynamic resistance' of commercially available SuperPower and Fujikura CC wires in an AC perpendicular field. The onset of dynamic resistance occurs at a threshold field amplitude, which is determined by the total DC transport current and the penetration field of the conductor. We show that the field-dependence of the normalised magnetisation loss provides an unambiguous value for this threshold field at zero transport current. From this insight we then obtain an expression for the dynamic resistance in perpendicular field. This approach implies a linear relationship between dynamic resistance and applied field amplitude, and also between threshold field and transport current and this is consistent with our experimental data. The analytical expression obtained yields values that closely agree with measurements obtained across a wide range of frequencies and transport currents, and for multiple CC wires produced by different wire manufacturers and with significantly differing dimensions and critical currents. We further show that at high transport currents, the measured DC resistance includes an additional nonlinear term which is due to flux-flow resistance incurred by the DC transport current. This occurs once the field-dependent critical current of the wire falls below the DC transport current for part of each field cycle. Our results provide an effective and simple approach to calculating the dynamic resistance of a CC wire, at current and field magnitudes consistent with those expected in superconducting machines. This is the Accepted Manuscript version of an article accepted for publication in 'Superconductor Science and Technology'. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6668/aa54e5.

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Section: Introductionsupporting

confidence: 74%

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Jiang¹,

Toyomoto²,

Amemiya³

et al. 2021

Preprint

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“…Table I shows the specifications of the HTS tape used for this study. This tape conductor is fixed in a developed sample holder, which can measure transport current loss in external magnetic fields with various magnitudes and phase differences [3], [4].…”

Section: Introductionmentioning

confidence: 99%

“…For the measurement a pair of voltage tap is attached on the tape conductor, and the wires from the taps are arranged in '8' shape to minimize the effect of environmental field [3], [4]. The AC loss of the conductor can be calculated from measured current and voltage signals.…”

Section: Introductionmentioning

confidence: 99%

Effect of AC Magnetic Field on Transport Current Loss of HTS Tapes

Kim

Ryu

Huh

et al. 2004

IEEE Trans. Appl. Supercond.

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It is known that external magnetic field not only causes the magnetization loss in a superconducting tape, but also increases the transport current loss, by the so-called "dynamic resistance." In power applications, superconductors carrying alternating current should be in alternating magnetic field. The frequency of the field is usually the same as that of the transport current, but they have phase difference. We developed an experimental system, which can measure transport current loss in external AC magnetic fields. With this equipment, we explored the effect of external field on the transport current loss with various field strengths and phase differences. This paper describes experimental results and discussions on the effect of amplitude and phase on transport current loss of HTS (High Temperature Superconductor) tape.Index Terms-AC loss, HTS tape, magnetic field, phase difference, transport current loss.

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“…Recently [10], we have shown that we can describe the operation of such devices using a simple electrical circuit model (Figure 1), in which the flux pump is considered to be a voltage source with an effective internal resistance, R d . This internal resistance is due to Dynamic resistance, a well-known phenomenon [11][12][13][14][15][16] which occurs in a type-II superconductor carrying a DC transport current whilst simultaneously experiencing an alternating imposed magnetic field. The other key parameter to describe the operation of these devices is the open-circuit DC voltage, V oc , which is generated across the flux pump.…”

mentioning

confidence: 99%

“…In this paper we present experimental measurements of R d and V oc from our prototype mechanically-rotating flux pump. The physics underlying dynamic resistance is well described [11][12][13][14][15][16] by conventional AC loss theory. However, at present, the physics underlying the origin of the DC open-circuit voltage in these devices is not so well understood, and there is no equivalent literature.…”

mentioning

confidence: 99%

Impact of flux gap upon dynamic resistance of a rotating HTS flux pump

Jiang

Bumby

Badcock

et al. 2015

Supercond. Sci. Technol.

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HTS flux pumps enable superconducting currents to be directly injected into a magnet coil without the requirement for thermally-inefficient current leads. Here, we present results from an experimen tal mechanically-rotating HTS flux pump employing a coated-conductor stator and operated at 77 K. We show the effect of varying the size of the flux gap between the rotor magnets and coated conductor stator from 1 mm to 7.5 mm. This leads to a corresponding change in the peak applied perpendicular magnetic field at the stator from approximately 350 mT to 50 mT. We observe that our experimental device ceases to maintain a measurable output at flux gaps above 7.5 mm, which we attribute to the presence of screening currents in the stator wire.We show that our mechanically-rotating flux pump is well described by a simple circuit model which enables the output performance to be described using two simple parameters, the open-circuit voltage Voc and the internal resistance, Rd. Both of these parameters are found to be directly proportional to magnet-crossing frequency and decrease with increasing flux gap. We show that the trend in Rd can be understood by considering the dynamic resistance experienced at the stator due to the oscillating amplitude of the applied rotor field. We adopt a literature model for the dynamic resistance within our coated-conductor stator and show that this gives good agreement with the experimentally measured internal resistance of our flux pump.

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Transport Loss Characteristics of the Bi-2223 Tapes in an External AC Magnetic Field

Cited by 11 publications

References 7 publications

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Effect of AC Magnetic Field on Transport Current Loss of HTS Tapes

Impact of flux gap upon dynamic resistance of a rotating HTS flux pump

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