Conceptual Design and Numerical Analysis of 10 MW Fully Superconducting Synchronous Generators Installed with a Novel Casing Structure

Currently, feasibility studies on fully turboelectric propulsion systems for electric aircrafts are being conducted worldwide. A fully superconducting rotating machine can realize fully turboelectric propulsion systems with light weight and high power density. In the simple casing model considered in a previous study, the field winding forms a large percentage of the generator weight. Therefore, to reveal the relationship between the operation temperature of the field winding and output power density, we compared an inner cryostat model having a field winding operation temperature of 20 K with the simple casing model having a field winding operation temperature of 64 K in terms of the output power density, efficiency, and increasing temperature. The stator and rotor rooms of the inner cryostat model were insulated by introducing the vacuum layer. The inner cryostat casing structure can have a lower refrigerant gas temperature, e.g., 20 K. Consequently, the temperature of the simple model increased from 5.4 to 7.1 K and that of the inner cryostat model increased from 3.0 to 6.1 K. The simple and inner cryostat models' power densities were 18.8 and 21.7 kW/kg, respectively. Both models achieved 99% efficiency. No major difference was observed between both models in terms of efficiency and output power density.