| Project/Area Number |
12650283
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電力工学・電気機器工学
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| Research Institution | Kyushu University |
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Principal Investigator |
IWAKUMA Masataka Graduate school of information science and electrical engineering, Asso. Prof., 大学院・システム情報科学研究院, 助教授 (30176531)
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| Co-Investigator(Kenkyū-buntansha) |
KAJIKAWA Kazuhiro Graduate school of information science and electrical engineering, Assistant researcher, 大学院・システム情報科学研究院, 助手 (10294894)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Oxide superconductor / Parallel conductor / Transposition / Ac loss / Current distribution / Superconducting transformer |
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| Research Abstract |
We overthrew the conventional theory for the formation of superconductors with low-Tc superconducting wires and proposed that the configuration of transposed parallel conductors is the most suitable for oxide superconducting wires. In this paper, we investigated the ac loss properties of superconducting parallel conductors. We first introduced the basic equation of magnetic field on the supposition that a 2-strand parallel conductor composed of superconducting multifilamentary wires with a rectangular cross section which are transposed only once, is exposed to a uniform magnetic field. By solving it, we deduced the theoretical expressions of the additional ac losses due the formation of parallel conductors. We also studied the applicability of superconducting parallel conductors to pancake-coils and solenoidal coils. The obtained conclusion is as follows.
1) In the case that the strands are transposed at the optimum position and the interlinkage magnetic flux is cancelled out, the shielding current is not induced. The additional ac loss is produced in case that the transposition deviates from the optimum condition.
2) In the case that the induced shielding current is less than the critical current of a strand, Ic, the additional ac loss is proportional to the square of field amplitude, Bm^2, and the square of the deviation length, Δ1^2, and has a debye-type frequency dependence.
3) In the case that the induced shielding current reaches Ic, the additional ac loss is proportional to Bm and Δ1 and has no frequency dependence.
4) The optimum transposition in the coils which are wound with 2- to 4-strand parallel conductors were clarified.
We concluded that ac losses in superconducting parallel conductors in the usual situation are so small that the ac loss density is nearly equal to that in the constituent strands. The availability of superconducting parallel conductors was verified.
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