Energy loss study for AC excited superconducting coils

该项目是对交流激励超导线圈的能量损耗进行研究。使用超导带缠绕成线圈是高温超导最有效应用的共同特征。然而，这些磁带是高度敏感的交流损失所产生的随时间变化的磁场垂直于磁带的横截面宽度。这对交流线圈的设计施加了一些约束，特别是对于电机中的定子绕组。在真实的应用中，我们有一个AC和DC磁场的组合作用于线圈，而线圈又有DC或AC传输电流。此外，磁场不是均匀的，甚至不是正弦曲线，电流也是如此。在存在大背景场或电流的情况下，磁场和传输电流的小叠加波纹的这种效应对于HTS电动机和发电机是非常关注的，并且尚未详细研究。我们强调的重要性，研究线圈在真实的配置的磁场和电流的特定系统。在这种情况下，实验测量可能是更可靠的modeling.We将研究高温超导线圈实验使用液氮蒸发和电气技术，这些结果将被用来验证描述线圈的数值模型。我们相信这种方法的组合将提供一个可靠的系统，为实际用户systems.As这项工作的输出，我们将有：（i）磁带的相关参数和整体线圈属性之间的互连的工作知识;（ii）一个可靠的实验技术，用于确定线圈的能量损失;（iii）验证线圈模型，作为设计和建造大型电机的数据来源。

The project is for energy loss study for AC excited superconducting coils.The use of superconducting tape wound into coils is a common feature of the most effective applications of HTS. However, these tapes are highly sensitive to AC losses produced by time-varying magnetic field perpendicular to the cross-sectional width of the tape. This imposes some constraints upon the design of ac coils particularly for stator windings in electrical machines. In real applications, we have a combination of AC and DC magnetic fields acting on a coil that, in turn, has DC or AC transport current. Moreover, magnetic fields are not uniform and not even sinusoidal and the same is true for currents. This effect of small superimposed ripples of magnetic field and transport current in the presence of large background field or current is a great concern for HTS motors and generators and it has not been studied in detail. We stress the importance of studying coils in real configurations of magnetic fields and currents for particular systems. In this case, experimental measurements are likely to be more reliable than modelling.We will study HTS coils experimentally using both liquid nitrogen boil-off and electrical techniques and these results will be used to validate numerical models describing coils. We believe this combination of methods will deliver a reliable system for characterising the performance of coils for practical user systems.As the output of this work, we will have: (i) a working knowledge of the interconnection between relevant parameters of the tape and the overall coil properties; (ii) a reliable experimental technique for determining the energy loss in coils; (iii) validated coil models as a data source for the design and construction of large-scale electrical machines.