AC losses in HTS bulk at various temperatures

HTS bulks applied to electric machines are exposed to AC magnetic field perturbations which cause AC losses in the bulks. AC losses affect the efficiency of the machines and decay the trapped magnetic field in an HTS bulk. Critical current density and the maximum trapped magnetic field of a bulk are...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2005-06, Vol.15 (2), p.2879-2882
Main Authors: Yamagishi, K., Asaba, I., Sekizawa, S., Tsukamoto, O., Ogawa, J., Kikukawa, K., Hirakawa, M.
Format: Article
Language:English
Subjects:
AC loss
Alternating current
Amplitude estimation
Applied sciences
Bulk density
Critical current density
cryo-cooler
Decay
Electric machines
Electrical engineering. Electrical power engineering
Electrical machines
Exact sciences and technology
Frequency estimation
Frequency measurement
High temperature superconductors
HTS bulk
Loss measurement
Magnetic field measurement
Magnetic fields
Miscellaneous
Perturbation methods
Studies
Superconductivity
Temperature
Temperature dependence
trap magnetic field
Trapped magnetic fields
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Summary:HTS bulks applied to electric machines are exposed to AC magnetic field perturbations which cause AC losses in the bulks. AC losses affect the efficiency of the machines and decay the trapped magnetic field in an HTS bulk. Critical current density and the maximum trapped magnetic field of a bulk are enhanced as temperature is decreased. Thereby, the lower temperature operation of the bulk is preferable. The AC losses in the bulk and their influence on the trapped magnetic field are dependent on the temperature. Therefore, to estimate the efficiency and decay of the trapped magnetic field at various operation temperatures, it is necessary to know the temperature dependence of the AC losses. We investigated AC loss characteristics of a bulk at various temperatures. In the work, AC losses were measured for the amplitude of the AC external magnetic field up to 0.08 T and frequency 17.3 Hz/spl sim/62.2 Hz at the temperature 65 K/spl sim/100 K. It is also shown that the temperature dependences of the AC losses are well estimated by a theoretical model based on the Bean model.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2005.848253