Electromagnetic analysis of fully superconducting motors employing dilute gas rotor and liquid hydrogen stator cooling structure

Abstract

This paper deals with fully superconducting motors (FSCMs) applied in the electric aircraft propulsion systems; the stator employs the MgB2-superconductor (SC) armature windings cooled at 20 K by using liquid hydrogen, while the rotor has the field windings made of REBCO SC wires cooled below 50 K via heat conduction and convective heat transfer by using dilute gas. The cooling structure of rotor can be simplified by adopting this type of design. The authors evaluated the optimal design for FSCM by using analytical equations and loss analysis via FEM. The FSCM characteristics were compared between ones using electromagnetic shield made of stainless steel (SUS) and ones using the shield made of copper (Cu); the results show that the output density using the SUS shield achieved 18.3 kW/kg, and that in terms of the loss estimation via FEM, both the motors had the efficiency over 98.5%.