In this work we present a modeling tool designed to estimate the hysteretic losses in the coils of an electric generator with coils made of coated conductor tapes during transient operation. The model is based on a two-stage segregated model approach that allows simulating the electric generator and the current distribution in the superconducting coils using a one-way coupling from the generator to the HTS coils model. The model has two inputs: the rotational speed and the electric load signal. A homogeneous anisotropic bulk model for the coils allows computing the current distribution in the coils. From this distribution, the hysteretic losses are estimated. Beyond the interest on providing an estimate on the global energy dissipation in the machine, in this work we present a more detailed local analysis that allows addressing issues such as coil design, critical current ratting, electric load change rate limits, cryocooler design, identification of quench-prone regions and overall transient performance.
A trapped field of 13.4 T in a stack of HTS tapes with 30 μm substrate
超导体(RE)Ba $_2$ Cu $_3$ O $_{7-x}$材料(RE-稀土元素)已成功地用于产生超过17 T的磁通量密度。这项工作研究了另一种方法,通过捕获磁通量的第二代高温超导磁带从几个制造商使用场冷却和脉冲场磁化技术的堆栈。高达13.4 T的磁通密度被困在两个12平方毫米的堆栈之间的磁场冷却在~5 K,比以前的值在高温超导磁带堆栈中实现了70%的改善。捕获的磁通量接近(RE)BCO块材的记录值,反映了高温超导带材性能的快速发展。
A compact HTS cable that is able to carry large current density is crucial for developing high field accelerator magnets. We are reporting a novel HTS cable (named X-cable) that could achieve a high current density as the Roebel cable, but is implemented by in-plane bending stacked HTS tapes directly to realize the transposition. The cable is jointly developed with an industrial company on a production line: ready for large scale production from the beginning. Recently, a prototype cable with REBCO coated conductor has been successfully fabricated. Test results show no significant degradation,…
Bending-like stress induced by solder joint under uniaxial tensile testing in 2G-HTS tapes: Impact and optimization approach
School of Electrical Engineering, Shanghai Jiao Tong University(上海交通大学电气工程学院);State key Laboratory of High-Efficiency special cable technology, Shanghai Jiao Tong University(上海交通大学高效特种电缆技术国家重点实验室);Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences(中国科学院电气工程技术研究所超导应用重点实验室);University of Chinese Academy of Sciences(中国科学院大学)
Numerical models based on the finite-element method (FEM) are popular tools for investigating the macroscopic electromagnetic behavior of high-temperature superconductor (HTS) applications. This article explains how to use the $T$-$A$ formulation for modeling HTS coils in 2D with different coupling scenarios between the turns. First we consider a racetrack coil wound from one piece of superconducting tape. Then we consider a coil obtained by winding a cable composed of different HTS tapes. In the latter case, the tape turns are either electrically connected along their entire length or just at…
Estimation of hysteretic losses for MgB2 tapes under the operating conditions of a generator
作为西班牙公司Tecnalia Research and Innovation领导的欧洲项目SUPRAPOWER的一部分,对500千瓦同步混合发电机的MgB 2绕制超导线圈的滞后损耗进行了估计。特别感兴趣的是,在超导转子中的磁带中发现的损失所造成的磁通量纹波源自传统的定子在标称操作。为了计算损耗,应用2D有限元方法来求解麦克斯韦方程的H-公式,考虑超导材料及其周围Ni矩阵的非线性特性。为了能够对构成超导转子线圈的绕组的所有不同匝进行建模,研究了复杂性降低的单带截面的三个几何模型:1)第一个模型与从显微照片获得的实际截面非常接近,2)第二个模型是从计算的圆镍丝的弹塑性变形获得的,3)最后一种模型是基于简化的椭圆截面。最后的几何形状允许通过比较数值损失与从完善的解析表达式的结果来验证建模技术。此外,还研究了以下细丝转位情况:无、部分和完全转位。最后,选择正确的几何细节水平来预测转子中单个超导带材的预期行为,研究了以下操作制度:偏置直流电流,斜坡背景场下的斜坡电流,以及直流背景电流和磁场下的磁通量波纹。
Striating HTS coated conductor (CC) tapes into narrow filaments offers the possibility of reducing the tapes' magnetization losses without unreasonably decreasing their current-carrying capability. However, realizing well-separated striations presents technological challenges, especially if the number of filaments is large and/or if a thick layer of metallic stabilizer is present. In these situations, the filaments can be easily coupled and their effectiveness to reduce magnetization losses is strongly diminished or eliminated. While the onset of coupling is well visible from magnetization los…
This study presents an HTS electromagnetic model combining the thin-strip, homogeneous and multi-scale methods using T-A formulation. In particular, we build the thin strips as both the analyzed HTS tapes and the boundaries of the homogeneous bulks where the non-analyzed tapes are merged. Thus, the coil geometry is re-constructed with several bulks, but the bulks boundaries and domains are tackled with different electromagnetic properties, and solved by T and A formulations, respectively. Firstly, we introduce the modeling process and highlight the differences and advantages over the previous …
Local electromagnetic properties and hysteresis losses in Non-Uniformly wound 2G-HTS Racetrack Coils
一个值得注意的物理依赖性的磁滞损耗与轴向绕组的商业\textcolor{black}{Second Generation High Temperature Superconducting (2G-HTS)}磁带的超导跑道线圈的错位的报告。全面研究了匝间不对准因子对单个匝的局部电磁特性的影响,考虑了六种不同的线圈布置和十个施加的交变传输电流$I_{a}$的振幅,以及实验确定的临界电流密度$J_{c}(B,θ)$的磁角各向异性特性的函数。已经发现,对于中等到低的施加电流$I_{a} \leq 0.6~I_{c0}$,其中$I_{c0}$是各个带的自场临界电流,在极端绕组变形下所产生的滞后损耗可以导致能量损耗的增加高达由完美缠绕的线圈产生的损耗的$25\%$。高层次的网格的考虑已被应用,以获得一个现实的帐户的局部和全局的电磁性能的跑道线圈,…我们的研究结果可以作为一个实际的基准,以确定任何2G-HTS赛道线圈应用的相对损耗,揭示可能的线圈绕组错位可以推断的物理指纹。
For an accurate estimation of the AC losses of superconducting triaxial cables, we present a 2D model capable to provide a global assessment of multi-layer triaxial cables, validated against the AC-losses on single-phase cables provided by the VNIIKP Cable Institute. Four models are presented, the first being a single-phase cable of 50 tapes and the others being three triaxial cables made of up to 135 coated conductors distributed in up to 9 layers. A systematic study is devised, where the number of layers per phase increases from 1 to 3, with at least 14 tapes distributed across each layer of…
Various applications of superconducting materials require accounting of anisotropy of the current-carrying capacity relative to magnetic field direction - Ic(θ). However, today there is no sufficiently comprehensive model that takes into account the anisotropy, therefore the angular dependences are usually not analysed, but only described using various mathematical formulas. As a result, the fitting parameters have no physical meaning and it is difficult to correlate the picture with the features of the microstructure. In this paper, we propose a method for analysing the critical current angul…
High temperature superconducting (HTS) dynamos are promising devices that can inject large DC currents into the winding of superconducting machines or magnets in a contactless way. Thanks to this, troublesome brushes in HTS machines or bulky currents leads with high thermal losses will be no longer required. The working mechanism of HTS dynamo has been controversial during the recent years and several explanations and models have been proposed to elucidate its performance. In this paper, we present the first three-dimensional (3D) model of an HTS flux pump, which has good agreement with experi…