Programmable Superconducting AC Machine (PSAM)

磁路设计是最终解决方案成功的基础。为了降低开发超导使能技术的风险，演示设计将基于使用标准磁钢和几何结构，以实现气隙磁通密度的加倍。某些磁性材料的特性在低温下是已知的，但特定的关键数据，如交流电，居里点和饱和磁通密度的可用性非常有限。剑桥大学最初将通过指导选择最合适的常规磁钢用于演示器来支持该项目，沿着对用于演示器性能建模的未识别材料数据的指导。磁性材料的优化是实现完全超导机器的全部好处的关键。对于可编程磁体，主要挑战是优化材料的居里和饱和点，以及这如何影响优选的充电周期和实际磁体工作温度。这又引导磁化夹具的优选位置。对最佳磁性材料的一个重大挑战已被确定为制造过程的质量、热处理和材料的化学成分。化学组成影响居里温度和电荷载流子密度。热处理曲线影响离子向氧晶格中的扩散，并且制造方法影响材料的均匀性和均一性。对于超导定子，主要的挑战是通过创建低磁阻路径来最大化链接超导线圈的磁通。使用高磁导率材料可以实现防止磁通泄漏，这将降低超导体的磁通链和工作点。尽管提案原始形式文件第3页（共9页）打印日期：16/02/2011 09：39：22 TS/J 001082/1保存日期：15/02/2011 15：49：48目前在目标低温25 K下存在的机械、热和磁性材料属性数据极其有限，但已观察到在低温下使用铁对直流超导磁体产生了益处。然而，对于低温交流磁系统，需要重新访问该约定。需要进一步考虑磁性材料提供低磁阻路径同时提供非常低的损耗密度的能力。存在的显著风险是，常规钢在低温下将引起显著的涡流损耗（由于增加的电导率）和更高的磁滞损耗，导致不切实际的低温解决方案。需要了解一系列磁钢的损耗密度、热性能和磁性能随频率的变化。工作还应考虑替代的非常规室温材料，这些材料在低温下也可能表现出增强的渗透性。这项工作本质上还必须考虑材料在热应力和机械应力下的长期稳定性。本研究的结果可能会导致不同的机器结构，例如永磁体固定夹具的位置，冷却回路结构和整体机器拓扑结构，例如要考虑的内部机器。这一工作将用于指导全尺寸的轮廓设计。

The magnetic circuit design is fundamental to the success of the final solution. To reduce the risk of developing the superconducting enabling technology the demonstrator design will be based on using standard magnetic steels and geometry architectures to achieve a doubling of the air-gap flux density. Some magnetic materials characteristics are known at cryogenic temperatures but the availability of particular key data such as ac electrical, Curie point and saturation flux density is very limited. The University of Cambridge will initially support the project by directing the selection of the most suitable conventional magnetic steel for use in the demonstrator, along with guidance on unidentified material data for use in modelling the demonstrator performance. The optimisation of magnetic materials is key to enabling the full benefits of a totally superconducting machine to be realised. For the programmable magnets the main challenges are the optimisation of the Currie and saturation point of the materials and how this impacts the preferred charging cycle and the actual magnet operating temperature. This in turn directs the preferred location of the magnetising jig. A significant challenge to an optimum magnetic material has been identified as the quality of the manufacturing process, heating treatment and the chemical composition of the material. The chemical composition affects the Curie temperature and the charge carrier density. The heat treatment profile affects the diffusion of the ions into the oxygen lattices and the manufacturing method affects the homogeneity and uniformity of the material. For the superconducting stator the main challenges are maximising the flux linking the superconducting coil by creating a low reluctance path. The prevention of flux leakage that will reduce both the flux linkage and the operating point of the superconductor can be achieved using a high permeability material. Although Proposal original proforma documentPage 3 of 9 Date printed: 16/02/2011 09:39:22TS/J001082/1 Date saved: 15/02/2011 15:49:48extremely limited mechanical, thermal and magnetic material property data currently exists at the cryogenic temperature of interest 25K, it has been observed that the use of iron at cryogenic temperatures has yielded benefits for dc superconducting magnets. However, for cryogenic ac magnetic systems, this convention needs to be re-visited. The ability of magnetic material to provide a low reluctance path whilst providing very low loss densities will need further consideration. There is a significant risk that conventional steels at cryogenic temperatures will incur significant eddy current losses (due to the increased electrical conductivity) and higher hysteresis losses leading to an impractical cryogenic solution. The loss density, thermal and magnetic performance as a function of frequency of a range of magnetic steels needs to be understood. Work should also consider alternative non-conventional room temperature materials that may also exhibit enhanced permeabilities at cryogenic temperatures. This work by its nature must also consider the long-term stability of the material under thermal and mechanical stresses. It is likely that the result of this study may lead to different machine constructions such as the location of the permanent magnet fixture jig, the cooling circuit construction and the overall machine topology such as an inside machine to be considered. This work will used to guide the full-scale outline design.