자장방향이 적층 Bi-2223도체의 자화손실에 미치는 영향

류경우,김현준 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.1

The ac loss is an important issue in the design of high-Tc superconducting power devices such as transformers and cables. In these devices many Bi-2223 tapes are closely stacked together and exposed to alternating magnetic fields that can have different orientations with respect to a tape. In such arrangement the magnetization loss is influenced by the screening current induced in adjacent tapes and thus different from that in a single tape. This stacking effect was experimentally investigated by measuring the magnetization loss in a stack, which consists of a number of tapes. First the magnetization loss in the single tape was measured in order to confirm the reliability of the loss data measured in the stack. The results for the single tape coincide well will the loss characteristics described in other previous works. For the stack In parallel and longitudinal magnetic fields the measured loss is Independent of both the number of tapes and stacking type. The longitudinal magnetization loss Is well explained rather by the slab model for decoupled filaments. For the tall stack in perpendicular field the measured loss at low fields is greatly decreased, compared to the loss of the single tape. However the loss at high fields is unaffected. These loss behaviors in the tall stack are well described by the slab model for full coupling.

Levitation characteristics of HTS tape stacks

Pokrovskiy, S.V.,Ermolaev, Y.S.,Rudnev, I.A. The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.1

Due to the considerable development of the technology of second generation high-temperature superconductors and a significant improvement in their mechanical and transport properties in the last few years it is possible to use HTS tapes in the magnetic levitation systems. The advantages of tapes on a metal substrate as compared with bulk YBCO material primarily in the strength, and the possibility of optimizing the convenience of manufacturing elements of levitation systems. In the present report presents the results of the magnetic levitation force measurements between the stack of HTS tapes containing $n=2{\div}200$ of tapes $12mm{\times}12mm$ and NdFeB permanent magnet in the FC and ZFC regimes. It was found a non- linear dependence of the levitation force from the height of the array of stack in both modes: linear growth at small thickness gives way to flattening and constant at large number of tapes in the stack. Established that the levitation force of stacks comparable to that of bulk samples. The numerical calculations using finite element method showed that without the screening of the applied field the levitation force of the bulk superconductor and the layered superconductor stack with a critical current of tapes increased by the filling factor is exactly the same, and taking into account the screening force slightly different.

Estimation of magnetization loss at angular magnetic field using perpendicular magnetization loss in striated and transposed YBCO coated conductor

Lee, J.K.,Kim, W.S.,Park, C.,Byun, S.,Han, B.W.,Lee, S.,Park, S.,Choi, K. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

The magnetization loss in a perpendicular external magnetic field is main AC loss of YBCO coated conductor for AC power applications. One of solutions for decreasing the magnetization loss is to make striations on it and to transpose the striated coated conductors. We measured the magnetization losses of several samples made by striated and transposed YBCO coated conductors in external magnetic field with an inclined angle for wide face of YBCO coated conductor. We compared the measured magnetization loss at an arbitrary direction in the magnetic field with those measured in a perpendicular magnetic field at the same value of perpendicular component of the external magnetic field. The results agree well with each other in all samples. This means that the magnetization loss in any directional applied magnetic field can be estimated by using only the perpendicular loss data.

YBCO Coated Conductor와 BSCCO tape의 적층 및 외부자장의 각도에 따른 자화손실 특성

임형우,이희준,차귀수 한국초전도저온학회 (구 한국초전도저온공학회) 2005 한국초전도저온공학회논문지 Vol.7 No.3

적층 형태의 고온 초전도선재에서의 통전손실 수치 해석

최세용,나완수,김정호,주진호,류경우 한국초전도학회 2004 Progress in superconductivity Vol.5 No.2

We have studied alternating transport current losses in the vertically stacked high temperature superconducting tapes(HTS) using numerical techniques. In the case of stacked conductors, HTS tapes are exposed to self-field generated by transport current itself and also experienced external magnetic field around adjacent tapes. It is well known that magnetic interactions between neighbored tapes have significant effect on their properties of superconducting tapes such as current distribution, AC loss, and critical current. In this paper, we investigated the transport current losses in stacked conductors consisting of a few of the HTS tapes using numerical analysis. Current distributions are calculated in HTS tape cross-section taking account of magnetic field dependencies, which are represented superconducting nonlinear properties. Dissipated losses in tape and stacked conductors were integrated with current distribution and electric field intensity in the whole conductor region. Finally estimated results were discussed and verified through the analytical theory.

YBCO CC 적층 및 BSCCO tape 적층선재에서 수직자화 손실 값을 이용한 임의 방향 자화손실 평가

李志光(Ji-Kwang Lee),林炯佑(Hyoung-Woo Lim),朴明鎭(Myung-Jin Park),車貴守(Gueesoo Cha) 대한전기학회 2007 전기학회논문지 Vol.56 No.2

Magnetization loss of high temperature superconductoring BSCCO tape and YBCO coated conductor(YBCO CC) is most important issue in the development of superconducting power devices. In this paper, the measured results of magnetization losses under various angles of external magnetic field in BSCCO tape stacked conductors and YBCO CC stacked conductors are presented and compared with each other. Also, we present the compared results of magnetization losses measured at arbitrary directional magnetic fields and analyzed with perpendicular magnetic field components of those. The results show that magnetization losses of YBCO CC single and stacked conductors agree well with the analyzed value by it's perpendicular magnetic field component, but BSCCO single and stacked conductors are not.

z 축으로 쌓은 GdBCO 초전도 선재의 교류 손실의 간격 및 쌓은 횟수 의존성

김찬,김영경,전성민,이형철 한국물리학회 2021 새물리 Vol.71 No.2

The 2G High-Tc superconductor-coated conductors (2G HTS CC) with large aspect ratios have large AC losses for a perpendicular external magnetic field. A reduction of the AC loss is an important issue in 2G HTS CC applications. In a previous study, stacking of HTS CC was found to increase the full penetration field Hp and to decrease the AC loss. The AC loss for the maximum applied magnetic field Hm below Hp was affected by the interval D and the staking number n. In this study, to reduce the AC loss, we stacked GdBCO-coated conductors with the same geometries and with regular D, and we measured the magnetization curves of the stacked samples at a temperature of 83 K (t = T/Tc = 0:88). The AC losses were calculated using the experimental results, and the AC losses of the stacked samples were compared with phose for the single-layer sample. We investigated the dependences on D and n of the AC losses of the stacked GdBCO CCs. As the interval decreases, the volume normalized AC loss decreased. In the case of D = 0.10 mm, the AC loss was decreased by 16% and 37% in the 2-layer structure and the 3-layer structure, respectively, compared with the 1-layer structure. 2세대 고온 초전도 선재는 종횡비가 크기 때문에 수직한 외부 자기장에 대한 교류 손실이 크다. 이러한2세대 고온 초전도 선재를 응용하기 위해서는 교류 손실을 줄이는 것이 중요한 문제이다. 이전 연구결과에 의하면, 고온 초전도 선재를 쌓으면 완전 침투장 (full penetration field, Hp) 이 증가하고 교류손실이 감소한다. 최대 인가 자기장 (maximum applied magnetic field, Hm)이 Hp 보다 작은 경우 교류손실은 초전도 선재간 간격 D와 쌓은 횟수 n의 영향을 받는다. 본 연구에서는 교류 손실을 저감하기 위한방안으로 같은 면적의 GdBCO 초전도 선재를 D만큼의 일정한 간격으로 쌓고 83 K (t = T/Tc = 0:88) 에서 시료의 자화 곡선을 측정하였다. 측정한 자화 곡선 결과로부터 교류 손실을 계산하고 쌓은 구조에따른 시료의 교류 손실을 단일 시료의 교류 손실과 비교하였다. 특히 교류 손실에 대한 선재 사이의 간격과쌓은 횟수의 의존성을 조사하였다. 선재 사이의 간격이 줄어들면 단위 부피로 규격화한 교류 손실이 줄어드는 경향을 확인하였고, D = 0.10 mm 일때 교류 손실이 1-layer 일때에 비해 2-layer 구조와 3-layer 구조에서 각각 16%와 37% 감소하였다

적층 배열형상에 따른 BSCCO 적층선재의 자호손실 특성 수치해석 및 측정

朴明陳(Myungjin Park),林炯佑(Hyoungwoo Lim),李光淵(Kwangyoun Lee),車貴守(Gueesoo Cha),李志光(Jikwang Lee) 대한전기학회 2006 전기학회논문지 B Vol.55 No.2

AC loss is one of the main research area in AC power application using high temperature superconductor(HTS), such as HTS transformer, HTS current limiter and HTS cable, because it is closely related to efficiency, economic estimation and design of power device. A lot of research for various arrangements of HTS tapes have been performed to increase a capacity of transport current because single HTS tape can not satisfy the demanded current capacity in HTS power application. In this paper, we studied magnetization loss by different several arrangements of BSCCO tapes such as Edge- to-Edge type, Face-to-Face type and Matrix type through numerical analysis by 2D-FEM and measurement. As a result, we got the result that the magnetization loss of Face-to-Face type arrangements was lower than those of other arrangement types under the conditions of the same stacking number. We think that the result was due to shield effect by demagnetization of adjacent HTS tapes which are located face to face.

An experimental analysis on the design of HTS current lead with respect to the arrangement of coated conductor and the shape of a current terminal

Chang, K.S.,Jang, J.Y.,Lee, J.,Ko, T.K. North-Holland 2011 Physica. C, Superconductivity Vol.471 No.21

Many researches on the application of superconducting tapes for large current apparatus have been conducted because of their advantages of low resistance and high efficiency. In the applications, superconducting tapes which are available below a critical current density should be arranged in the stacking or parallel structure for increasing a current capacity. However it is difficult to achieve large current capacity in each structure as much as expected; a simple stacking structure has a current distribution problem due to contact resistance between superconducting tapes and a parallel structure has the spatial limitation. In order to reduce the contact resistance, superconducting tapes should be stacked vertically and these tapes are connected by solder; therefore large current capacity can be achieved. In this paper, a design of a copper terminal for HTS current lead using a stacked HTS tapes and a parallel arrangement of stacked HTS tapes were analyzed and the operating characteristics were proved by experimental analysis.

Magnetization of the stack of HTS tapes

Osipov, M.A.,Abin, D.A.,Pokrovskiy, S.V.,Mineev, N.A.,Rudnev, I.A. The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.1

New results of dependence of magnetic field, trapped by a stack of HTS tapes, on amount of tapes in a stack are reported. Commercial GdBCO tape 12 mm width and without Cu layer was used for the research. Tape was divided in square pieces $12{\times}12mm^2$ from which stacks were formed. Filling factor of the tape was about 1.4%. Measurements were carried out for stacks with height from 5 to 250 pieces and at wide temperature range from liquid helium to liquid nitrogen. Both FC (field cooling) and ZFC (zero field cooling) cooling methods were used in the research. These two methods show matching results with good accuracy. As a result dependences of trapped magnetic flux on amount of tapes for different temperatures were received. Research shows, that with increasing height of the stack trapped magnetic field value reach saturation at about 60 tapes in a stack for low temperatures. From 60 to 100 tapes increase of magnet flux is only 5%. Thus increase amount of tapes in a stack is not profitable. Also investigation of trapped magnet field relaxation was carried out. Relaxation speed decreases with increasing amount of elements. It means that the higher the stack is, the longer trapped flux will be held in cause of the same temperature.