AC Loss and Voltage Signal in a Pancake Coil Made of Coated Conductor With Ferromagnetic Substrate

Pardo, Enric; Šouc, J; Vojenčiak, M.; Gömöry, Fedor

doi:10.1109/tasc.2009.2019064

Cited by 7 publications

(4 citation statements)

References 19 publications

(36 reference statements)

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“…There are practically no AC loss measurements for stacks of pancake coils. Most of the work is for single pancake coils, both for coated conductors with a ferromagnetic substrate [11][12][13] and a non-magnetic one [14,15], or double pancakes with a ferromagnetic substrate [16,17]. The only measurements for a stack of pancake coils is [18], where they use a coated conductor with a ferromagnetic substrate.…”

Section: Introductionmentioning

confidence: 99%

AC loss in ReBCO pancake coils and stacks of them: modelling and measurement

Pardo¹,

Šouc²,

Kováč³

2012

Supercond. Sci. Technol.

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Many applications of ReBCO coated conductors contain stacks of pancake coils. In order to reduce their high AC loss, it is necessary to understand the loss mechanisms. In this article, we measure and simulate the AC loss and the critical current, Ic, in stacks of pancake coils ("pancakes"). We construct stacks of up to 4 pancakes and we measure them by electrical means. We also obtain the anisotropic field dependence of Jc from Ic measurements of the tape. This Jc is the only input to the simulations, together with the coil dimensions. After validating our computations with the measurements, we simulate stacks of many pancakes, up to 32. We found that the AC loss in a stack of (four) pancakes is very high, two orders of magnitude larger than for a single tape. A double pancake behaves as a single one with double width but a stack of more pancakes is very different. Finally, we found that a 2-strand Roebel cable reduces the AC loss in a stack of pancakes but not in a single pancake. In conclusion, our simulations are useful to predict the ac loss of stacks of coated conductor pancake coils and to reduce the ac loss by optimizing the coil design.

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Section: Introductionmentioning

confidence: 99%

AC loss in ReBCO pancake coils and stacks of them: modelling and measurement

Pardo¹,

Šouc²,

Kováč³

2012

Supercond. Sci. Technol.

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“…The equivalent circuit for a typical AC susceptibility measurement system is shown in Figure 10. Pardo et al have measured the voltage signal and AC loss in a pancake coil made of CCs with the ferromagnetic substrate utilizing a SQUID magnetometer at 100 K [164]. However, it appears that the SQUID and VSM techniques are too slow for measurement at power frequencies.…”

Section: Magnetic Methodsmentioning

confidence: 99%

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

Zhang¹,

Wen²,

Grilli

et al. 2021

Energies

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Superconductor technology has recently attracted increasing attention in power-generation- and electrical-propulsion-related domains, as it provides a solution to the limited power density seen by the core component, electrical machines. Superconducting machines, characterized by both high power density and high efficiency, can effectively reduce the size and mass compared to conventional machine designs. This opens the way to large-scale purely electrical applications, e.g., all-electrical aircrafts. The alternating current (AC) loss of superconductors caused by time-varying transport currents or magnetic fields (or both) has impaired the efficiency and reliability of superconducting machines, bringing severe challenges to the cryogenic systems, too. Although much research has been conducted in terms of the qualitative and quantitative analysis of AC loss and its reduction methods, AC loss remains a crucial problem for the design of highly efficient superconducting machines, especially for those operating at high speeds for future aviation. Given that a critical review on the research advancement regarding the AC loss of superconductors has not been reported during the last dozen years, especially combined with electrical machines, this paper aims to clarify its research status and provide a useful reference for researchers working on superconducting machines. The adopted superconducting materials, analytical formulae, modelling methods, measurement approaches, as well as reduction techniques for AC loss of low-temperature superconductors (LTSs) and high-temperature superconductors (HTSs) in both low- and high-frequency fields have been systematically analyzed and summarized. Based on the authors’ previous research on the AC loss characteristics of HTS coated conductors (CCs), stacks, and coils at high frequencies, the challenges for the existing AC loss quantification methods have been elucidated, and multiple suggestions with respect to the AC loss reduction in superconducting machines have been put forward. This article systematically reviews the qualitative and quantitative analysis methods of AC loss as well as its reduction techniques in superconductors applied to electrical machines for the first time. It is believed to help deepen the understanding of AC loss and deliver a helpful guideline for the future development of superconducting machines and applied superconductivity.

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“…This situation is interesting not only for coils made of tapes with non-magnetic substrates but also for identifying the origin of the loss reduction in our coil. We studied the effect of the magnetic substrate on the AC loss in the superconducting layer in [24]. From the magnetic image effect [8], we discussed that the magnetic substrate has the same influence on the superconductor AC loss as increasing the coil number of turns.…”

Section: Simulationsmentioning

confidence: 99%

AC loss measurement and simulation of a coated conductor pancake coil with ferromagnetic parts

Pardo

Šouc

Vojenčiak

2009

Supercond. Sci. Technol.

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Magnetic diverters are commonly used in order to reduce the AC loss in superconducting coils. However, they have not been proved to work on YBa2Cu3O7−x-coated conductor coils. Moreover, modeling tools are required for predicting the resulting AC loss and understanding the loss mechanisms. In this paper, a coated conductor pancake coil with ferromagnetic diverter is measured and simulated. The magnetic diverter reduces the AC loss but the critical current practically does not change. Our simulations show that a diverter wider than that in the measurements can reduce the loss below that of a single strip. Therefore, the optimum diverter size should be obtained by simulations.

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AC Loss and Voltage Signal in a Pancake Coil Made of Coated Conductor With Ferromagnetic Substrate

Cited by 7 publications

References 19 publications

AC loss in ReBCO pancake coils and stacks of them: modelling and measurement

AC loss in ReBCO pancake coils and stacks of them: modelling and measurement

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

AC loss measurement and simulation of a coated conductor pancake coil with ferromagnetic parts

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