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本文首先介绍了单芯高温超导带材交流损耗的机理,然后以SMES磁体磁滞损耗计算为例,分析了两种单芯超导带材磁滞损耗计算模型的计算结果,发现在不同场强范围内两种模型计算结果有明显的差异,并给出了计算交流损耗时两种模型的适用范围.最后简要说明了两种模型计算结果不同的原因. 相似文献
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《低温与超导》2021,49(5):25-29
高温超导复合缆线的运行温度直接决定其载流性能,超导带材交流损耗计算的准确性对缆线的温升计算至关重要。面向具有铜骨架和双层高温超导带材结构的高温超导复合缆线,通过改进利兹线(Litz-wire)涡流损耗计算模型,将导电层作为利兹线结构中由多股线按一定节距扭转的束级结构的并联,分别计算了49.9 Hz和60 Hz下复合缆线的集肤效应损耗和邻近效应损耗。通过分析高温超导带材的平行磁场分量和垂直磁场分量,计算了复合缆线的磁滞损耗。最后,基于超导样缆交流损耗补偿测量系统,对0.2 m、110 kV/1.5 kA铜骨架高温超导复合缆线的交流损耗进行了测量,得到工频下1 200 A载流时的交流损耗为1.21 W。研究发现,在不同频率下,铜骨架高温超导复合缆线的交流损耗随传输电流的增大而增大。通过对比仿真和实验结果,验证了铜骨架高温超导复合缆线交流损耗计算结果的准确性。 相似文献
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《低温与超导》2017,(10)
Bi-2223/Ag是一种很有前景的高温超导带材,交流损耗是高温超导在大规模电力应用方面的瓶颈,如何降低Bi-2223/Ag中的交流损耗是人们一直关注的问题。带材超导部分的横截面形状对交流损耗有很大的影响,前人曾通过双轴轧制等工艺制造矩形截面的带材,以降低其交流损耗;另有人在单芯带材中得到了环状结构,从中发现可降低交流损耗。本论文尝试利用抽换芯工艺制造多芯环状截面的Bi-2223/Ag高温超导带材,以期降低带材的交流损耗。论文中,通过解析方法计算了临界态模型下,临界电流密度在径向上分布不均匀的超导体的交流损耗特性,并得到结论:带材的外围临界电流密度越高,交流损耗性能越好。 相似文献
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本论文对高温超导磁体在传输直流电流时产生的损耗进行了理论分析和实验验证.本文考虑了高温超导带材非线性模型磁场方向对带材临界电流和n值的影响,用Bi2223超导带材绕制了(一个由20个双饼组成的高温超导磁体,用数值仿真和实验方法研究了此磁体传输直流电流时的指数损耗.并对每个双饼以及每匝线圈的损耗进行了分析.在液氮温度下对一个双饼线圈进行了指数损耗的测量,测量结果与数值仿真结果相当吻合.利用高温超导体临界电流此非线性模型,本文对此磁体快速励磁情况下的交流损耗的特点进行了数值模拟. 相似文献
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本论文对高温超导磁体在传输直流电流时产生的损耗进行了理论分析和实验验证.本文考虑了高温超导带材非线性模型磁场方向对带材临界电流和n值的影响,用Bi2223超导带材绕制了(一个由20个双饼组成的高温超导磁体,用数值仿真和实验方法研究了此磁体传输直流电流时的指数损耗.并对每个双饼以及每匝线圈的损耗进行了分析.在液氮温度下对一个双饼线圈进行了指数损耗的测量,测量结果与数值仿真结果相当吻合.利用高温超导体临界电流此非线性模型,本文对此磁体快速励磁情况下的交流损耗的特点进行了数值模拟. 相似文献
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高温超导变压器的漏磁场降低绕组中的临界电流并增加交流损耗;超导材料的零电阻特性使得绕组限制环流的能力极低.因此,在设计超导变压器时,进行磁场分析和环流计算显得尤其重要.本文采用场-路结合的方法,即在用ANSYS求得反映变压器各支路之间电磁耦合的电感矩阵的基础上列出电路方程,计算了变压器低压绕组5种不同形式的各支路电流分布,并进而分析了磁场.同时提出了减小环流和改善磁场分布的一些措施. 相似文献
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高温超导磁体临界电流磁矢量分析法准确地预测了BSCCO高温超导磁体的临界电流,为了进一步验证该方法预测YBCO高温超导磁体临界电流的准确性,文中作者用9.3m二代高温超导YBCO带材绕制了一个内径为70mm,外径为100mm,共35匝的单饼,测试了单饼5-15匝,15-25匝,25-35匝和5-35匝在77K下的临界电流,并用磁矢量分析法进行了仿真分析。通过对比发现,仿真分析和实验结果的误差在5%左右,最大误差是6.75%,最小误差是4.77%,验证了磁矢量分析法在预测YBCO高温超导磁体临界电流时的准确性。 相似文献
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I.A. Nyrkova A.N. Semenov A. Aggeli M. Bell N. Boden T.C.B. McLeish 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):499-513
The classical isodesmic one-dimensional model for equilibrium polymerization is generalized in order to describe self-assembly
in systems forming fibrils. The model was applied to peptide solutions forming -sheet tapes which can further aggregate into stacks of various thickness: double tapes and fibrils (several double tapes
stacked together). We found that in some cases the model yields several step-like transitions as the concentration increases:
first from monomers to single or double tapes, and then to fibrils. The abruptness of the first transition is controlled by
the free energy penalty for transformation of a peptide from random coil to a straight -strand conformation (the latter is characteristic for tapes). If both single and double tapes are allowed, the length of
the aggregates after the first transition can be very large with high scission energies. For very low energies of attraction
between double tapes, the transition from double tapes to fibrils happens separately (above the first transition), and it
is even more abrupt and produces extremely long fibrils. The theoretical findings are used to extract the characteristic molecular
parameters for the self-assembly of the de
novo peptide DN1 forming polymeric -sheets in water.
Received 28 June 1999 相似文献
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Jozef Pitel Pavol Kov Imrich Hu
ek 《Physica C: Superconductivity and its Applications》2000,330(3-4):130-140
A mathematical model was developed to allow for the prediction of critical currents in Bi(2223)/Ag-sheathed tapes that consist of two groups of filaments, having crystalline texture (c-axis) predominantly in two directions orthogonal to each other and to the length of the conductor (filaments oriented parallel and perpendicular to the tape surface). Using the theory presented, it is possible to estimate the upper limit of critical currents in the tapes prepared with a two-axial rolling technique. Magnetic field and angular dependencies of critical currents were obtained at 77 K measuring tapes with various proportional representations of filaments oriented in both preferred directions, i.e., the parallel and perpendicular directions. The results of calculation indicate that the anisotropy in the Ic(B) characteristic should be reduced considerably using the two-axial rolling. Unfortunately, the effect of anisotropy reduction is accompanied by simultaneous decrease in the current-carrying capacity of the tapes. The data obtained for short tape samples were utilised to estimate the critical currents of the individual turns of a small cylindrical magnet, assembled of eight pancake coils. It is shown that only a slight increase in the critical current of the magnet can be expected if the winding should be made of the tape with reduced anisotropy in the Ic(B) characteristic. The factors that limit the increase of the magnet critical current are discussed in detail. 相似文献
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ITER电流引线高温超导叠制作工艺及性能测试 总被引:2,自引:0,他引:2
ITER高温超导电流引线载流能力最大要达到68 kA,一根电流引线共需要1000多根银金基Bi-2223高温超导带并联.这些高温超导带分成90叠,每叠由12层带组成.银金基Bi-2223带价格是普通银基Bi系带的4~5倍,而目前欧洲超导公司提供的超导叠的报价几乎是其带价格加倍,所以开发超导叠的制作工艺是非常有价值的.本文详细的介绍了超导叠的真空钎焊制作工艺,并进行了77 K下超导带的接头电阻测试和77 K自场下的临界电流测试,以及模拟在实际运行温度65~5 K条件下高温超导叠的载流能力测试和接头电阻的测试.测试结果证明了此工艺的可行性. 相似文献
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Demand for increased data storage has resulted in the development of various types of magnetic tapes. To achieve higher recording density, tape manufacturers are developing thin-film tapes, such as advanced metal-evaporated (AME) tape, for use in linear tape drives. In recent studies, these new AME tapes have demonstrated sustainable mechanical durability at low tensions suitable for use in linear tape drives. An evaluation of the magnetic performance of these AME tapes including the impact of tape cupping and initial edge quality was the goal of this study. Head output, dropouts, head–tape interface friction, and lateral tape motion (LTM) were monitored throughout testing. As track widths continue to narrow, LTM has become one of the critical limitations of magnetic performance. To more accurately measure LTM during drive development, a new method involving the output voltage of a head-read element that has been adjusted to be halfway off the recorded track on tape was implemented (LTMM). It is shown that positively cupped AME tapes will result in similar head output and fewer dropouts than the current MP tapes. The negatively cupped AME sample produced the lowest head output data and the highest amount of dropouts of all the tapes evaluated in this investigation. All the tapes evaluated demonstrated similar values of LTM when monitored at the center of the tape. When LTM was monitored at the lower edge of the tape, the positively cupped AME tape with the worst relative edge contour length resulted in the highest LTMM. As found in previous studies, AME tapes produced slightly lower values of coefficient of friction than the MP tapes. From this investigation, positively cupped AME tapes with good initial relative edge contour length are recommended for use in linear tape drives, similar to those used in this study. 相似文献
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Jakob Rhyner 《Physica C: Superconductivity and its Applications》1998,310(1-4):42-47
A method for the calculation of magnetic field dynamics and AC losses in superconductors with smooth current–voltage characteristics is described. It is based on an integral equation for the current density, recently used by Brandt for magnetic relaxation. Brandt's equation is generalized to include arbitrary external magnetic fields and transport currents. One of the benefits of the integral equation formulation is that no boundary conditions ‘at infinity' are required, thus restricting the calculation region to the conductor cross section. The method is applied to superconducting tapes in oblique external fields. A further extension of the theory is shown to be applicable to the calculation of coupling losses in twisted multifilamentary superconductors. 相似文献