Actively shielded air-core superconducting machines: optimization and design considerations

Superconducting electric machines hold immense promise for increases in power density, which is enabling for certain high-performance applications such as electric aviation and off shore wind generation. However, key challenges include limitations of magnetic materials and containment of fields within the machine, all while achieving the necessary cooling. This thesis explores the use of actively shielded air-core superconducting electric machines to address these challenges. A design concept is presented employing mature and low-cost Nb3Sn windings on a conduction cooled assembly. First, electromagnetic performance of the device is rigorously explored using evolutionary optimization techniques. Armature flux densities of up to 5 Tesla are shown to be achievable. Next, mechanical and cryogenic design aspects are discussed, along with preliminary analyses of key components. Hardware validation efforts to build a sample superconducting racetrack coil are then described. Bench test results indicate successful operation at fields near 6 Tesla and a critical current of 480 A. Finally, a qualitative discussion on potential field analysis methods for future work is given