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Superconducting tape-based stacks used as trapped magnetic flux magnets in electrical machines are subject to an AC-demagnetizing field. This study provides analysis of trapped flux and demagnetization of several stacks’ architectures for electrical machines applications. This work is an application-driven enhancement of a previous study on stacks architecture in regards of trapped flux profile and uniformity for applications requiring uniform magnetic field over a large area [1,2].
The trapped field and demagnetization of several stacks’ architectures made of SuperOx tapes were investigated. Using the same magnetizing field and the same number of tapes, rearranging the architecture of stacks was found to have an effect on the current density distribution, the trapped flux and the demagnetization. The electromagnetic time-dependent finite element model has been used; the latter implements the power law that takes into account field dependency of the superconductor critical current density and the power law exponent, n, at liquid nitrogen temperature interpolated from experimental characterization data.
Experimental measurements on some of the modeled architectures have been carried out to check the viability of the numerical models.
[1] T. B. Mitchell-Williams, A. Patel, A. Baskys, S. C. Hopkins, A. Kario, W. Goldacker, B. A. Glowacki, Towards Uniform Trapped Field Magnets Using a Stack of Roebel Cable Offcuts IEEE Transactions on Applied Superconductivity, 26 (3) 6800404 (April 2016)
[2] T B Mitchell-Williams, A Baskys, S C Hopkins, V Kalitka, A Molodyk, B A Glowacki and A Patel, Uniform trapped fields produced by stacks of HTS coated conductor tape, Superconductor Science and Technology, 29 (8) 085008 (16 June 2016)
Acknowledgements to:
This research is financially supported partially by the European Union’s Horizon 2020 research innovation programme under grant agreement No. 7231119 (ASuMED “Advanced Superconducting Motor Experimental Demonstrator”) and also by EPSRC grant No. EP/P000738/1 entitled “Development of superconducting composite permanent magnets for synchronous motors: an enabling technology for future electric aircraft”.
