Modeling and Electrical Measurement of Transport AC Loss in HTS-Based Superconducting Coils for Electric Machines

Ainslie, Mark; Yuan, Weijia; Hong, Zhiyong; Pei, Ruilin; Flack, T.J.; Coombs, Tim

doi:10.1109/tasc.2010.2089484

Cited by 45 publications

(25 citation statements)

References 27 publications

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“…In addition, both the external magnetic fields in the c-axis and that in the ab plane are applied to the superconducting stack by using dirichlet boundary conditions in the model [39,40]. …”

Section: Experiments Setupmentioning

confidence: 99%

Vortex shaking study of REBCO tape with consideration of anisotropic characteristics

Liang

Zhang

et al. 2017

Supercond. Sci. Technol.

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The second generation high temperature superconductor, specifically REBCO, has become a new research focus in the development of high-field (>25T) magnets. Previous research shows that applying an AC field in plane with the circulating current will lead to demagnetization due to vortex shaking. To unveil the vortex shaking mechanism of REBCO stacks， this paper provides an in-depth study, both experimentally and numerically,. A new experiment was carried out to measure the demagnetization rate of REBCO stacks exposed to an in-plane AC magnetic field. Meanwhile, 2D finite element models, based on the E-J power law, are developed to simulate the vortex shaking effects. Qualitative agreement was obtained between the experiment results and the simulation results. Our results show that the in-plane magnetic field leads to a sudden decay of the trapped magnetic field in the first half shaking cycle, due to magnetic field dependence of the circulating current. Furthermore, the decline rate of demagnetization with the increase of tape number is due to the increase of trapped magnetic field in the stack. Further study concerning the frequency of the applied AC magnetic field shows that it has little impact on the demagnetization process. Our modeling tool and findings will provide useful guidance in the development of future shaking devices for REBCO magnets.

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Section: Experiments Setupmentioning

confidence: 99%

Vortex shaking study of REBCO tape with consideration of anisotropic characteristics

Liang

Zhang

et al. 2017

Supercond. Sci. Technol.

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“…The finite-element model is based on the H-formulation, which directly solves the magnetic field components H = [H r , H z ] derived from Ampere's and Faraday's Laws, and is implemented here in 2D axisymmetric form using the AC/DC module of Comsol Multiphysics 4.3a [6]. More detailed information about the model formulation can be found in [7], [8], which was extended in [5], [9], [10] to allow for the inclusion of magnetic materials.…”

Section: Modelling Frameworkmentioning

confidence: 99%

Simulating the In-Field AC and DC Performance of High-Temperature Superconducting Coils

Ainslie

Zeng

et al. 2015

IEEE Trans. Appl. Supercond.

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In this paper, the authors investigate numerically the in-field behaviour of high-temperature superconducting (HTS) coils and a method to potentially improve their performance using ferromagnetic material as a flux diverter. The ability to accurately predict the electromagnetic behaviour of superconductors in complex geometries and electromagnetic environments is crucial to the design of commercially-viable superconductor-based electrical devices, such as power transmission cables, superconducting fault current limiters, transformers, and motors and generators. The analysis is carried out using a two-dimensional (2D) axisymmetric model of a circular pancake coil based on the H-formulation and implemented in Comsol Multiphysics 4.3a. We explore the use of flux diverters to improve an HTS coil's performance with respect to its DC (maximum allowable/critical current) and AC (AC loss) characteristics, for various background magnetic fields. It is found that while flux diverters can improve the AC properties of coils, they can be detrimental to the DC properties in this particular configuration.

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“…The comparison among three different measurement methods has been summarized in Table 4. Nowadays, the measurement of AC loss has been concentrated on simple single HTS tape or stacks of tapes [153,154,[193][194][195], and stationary coils [196][197][198][199][200][201]. It can be seen that the most widely adopted method is the electric method.…”

Section: Measurement Of the Cryogen Evaporationmentioning

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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Modeling and Electrical Measurement of Transport AC Loss in HTS-Based Superconducting Coils for Electric Machines

Cited by 45 publications

References 27 publications

Vortex shaking study of REBCO tape with consideration of anisotropic characteristics

Vortex shaking study of REBCO tape with consideration of anisotropic characteristics

Simulating the In-Field AC and DC Performance of High-Temperature Superconducting Coils

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

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