A Novel Brushless Superconducting Machine Topology With the Utilization of Composite Bulk Superconductor for Aerospace Applications

Adopting the stack of superconducting tapes as the excitation unit can bring a significant improvement to the performance of the electric machine compared to the permanent magnet. However, the limitation of the magnetizing condition leads to insufficient trapped field of stack of superconducting tapes. Therefore, approaches are raised in the paper to handle such an issue and improve the machine's performance. To maximize the excitation unit's remanent flux, surface-mounted topology is chosen. Besides, the composite bulk superconductor (CBS) constructed by stack of superconducting tapes and an iron core is utilized as the excitation unit for further enhancement of the trapped field. Since the proposed machine is targeted at aerospace applications, the attenuation of the trapped field, which is caused by the AC magnetic field in the airgap, should be considered carefully. Therefore, cryo-sleeve is adopted. Except for keeping CBS in position under high rotation speed, the proposed sleeve is also responsible for damping the AC magnetic field. COMSOL is utilized to simulate the proposed machine, and the superconducting region is solved with T-A formulation. Finally, a high-performance machine is built in this paper. The machine has an average airgap flux density of 2.00T and can output a power of 1.75MW with an efficiency over 99%.