Estimation of the Instantaneously Dissipated Hysteresis Losses in Superconductors

Schwerg, N.

doi:10.1109/tasc.2012.2195724

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…For Beanʼs case, the loss at the initial ramp increases as I 2 until it reaches an inflexion point (point 1 in figure 16). The I 2 dependence is explained by partial penetration by J c , as has been shown for slabs in an applied magnetic field [35]. The inflexion point corresponds to the penetration of the two pancakes from the top (figure 17(a) profile 1).…”

Section: Ac Losssupporting

confidence: 52%

Modeling of screening currents in coated conductor magnets containing up to 40000 turns

Pardo

2016

Supercond. Sci. Technol.

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Screening currents caused by varying magnetic fields degrade the homogeneity and stability of the magnetic fields created by REBCO coated conductor coils. They are responsible for the AC loss, which is also important for other power applications containing windings. Since real magnets contain coils exceeding 10000 turns, accurate modeling tools for this number of turns are necessary for magnet design. This article presents a fast numerical method to model coils with no loss of accuracy. We model a 10400-turn coil for its real geometry and coils of up to 40000 turns with the continuous approximation, which we checked that introduces negligible errors. The screening currents, the Screening Current Induced Field (SCIF) and the AC loss is analyzed in detail. The SCIF is maximum at the remnant state with a considerably large value and decreases substantially after one day of relaxation. The instantaneous AC loss for an anisotropic magnetic-field dependent Jc is qualitatively different than for a constant Jc, although the loss per cycle is similar. Saturation of the magnetization currents at the end pancakes causes that the maximum AC loss at the first ramp increases with Jc. The presented modeling tool can accurately calculate the SCIF and AC loss in practical computing times for coils with any number of turns used in real windings, enabling parameter optimization.

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Section: Ac Losssupporting

confidence: 52%

Modeling of screening currents in coated conductor magnets containing up to 40000 turns

Pardo

2016

Supercond. Sci. Technol.

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“…In addition, there are limitations in the measurement of instantaneous power loss. Although providing the correct loss per cycle, electrical measurements often read a false power loss signal [3,4]. Thermal measurements do not present this problem but their time response is slow.…”

Section: Introductionmentioning

confidence: 99%

Modeling of AC Loss in Coils Made of Thin Tapes Under DC Bias Current

Pardo¹

2014

IEEE Trans. Appl. Supercond.

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Many applications, such as magnets and SMES, are usually charged and discharged under a bias DC current, which may increase the AC loss. For their design, it is necessary to understand and predict the AC loss. This article analises the AC loss in magnet-like coils under DC bias contribution super-imposed to the AC current. The analyses is based on a numerical model that takes the interaction between magnetization currents in all turns into account. The studied example is a stack of 32 pancake coils with 200 turns each made of thin tape, such as ReBCO coated conductor. We present the current density, the instantaneous power loss, and loss per cycle. We have found that the loss increases with the DC bias current. The instantaneous power loss is the largest in the initial rise of the the AC current. In following cycles, the power loss is higher in the current increase than in the decrease. The loss per cycle is the largest at the end pancakes. In conclusion, the highest cooling power should be supplied to the top and bottom pancakes and during current rise, specially the initial one. The presented model has a high potential to predict the AC loss in magnet-size coils, useful for their design.

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