No abstract

For the development of electric propulsion aircrafts with light weight, low emission and high efficiency, MW-class fully superconducting synchronous machines operating at liquid nitrogen temperature were conceptually designed with REBa2Cu3O7-δ (REBCO) superconducting tapes in our previous studies. To verify the actualization of the structure and cooling method, a 1 kW-class prototype fully superconducting synchronous motor was designed and constructed in this study. The fixed armature was cooled with subcooled liquid nitrogen at 65 K. The rotor was cooled with helium gas. The pole number was two for the future high speed operation. The applicability of the complicated casing structure with three chambers into fully superconducting motor was also investigated from the viewpoint of thermal insulation. The operations as a motor up to 500 rpm and a generator demonstrated that the designed structure and cooling method were reasonable and effective for cooling the fixed armature and rotating field windings.

No abstract

Generators used in electric aircraft require a high-power density, and AC loss is also a significant problem. We designed 10 MW REBCO superconducting synchronous generators at 64 K to achieve a power density of 20 kW/kg and low AC loss. In this study, electromagnetic analyses were performed using finite element method software. Consequently, the thickness of the back yoke is 50 mm or less so that the generator can meet the target power density. The method of decreasing the magnetic field of the armature winding and increasing that of the field winding was used to effectively reduce the AC loss. As a result, the generator achieved a high-power density of 21.0 kW/kg, reducing the AC loss from over 600 kW to 415 kW.