Electromagnetic Design of kW-Class HTS Rotating Machines for Carbon-Neutral Ports

This paper presents the electromagnetic design and finite-element analysis of a kilowatt-class high-temperature superconducting field-switched rim-drive (HTS-FSR) rotating machine for carbon-neutral port applications. The proposed motor adopts a compact shaftless rim-drive topology with field wound HTS coils and is designed for direct liquid hydrogen (LH₂) cooling at a conceptual level to enable integration with hydrogen energy infrastructures. Three-dimensional finite element simulations are carried out to evaluate the magnetic flux distribution, torque characteristics, and associated electromagnetic loss tendencies under cryogenic (20 K) conditions. A performance comparison is made between a conventional 8 kW contra-rotating rim-drive thruster and the proposed design. HTS-FSR achieves a torque density of 27.0 kN·m/m³, which is approximately 1.5 times higher than that of the reference machine. These results demonstrate improved electromagnetic performance and indicate the scalability potential of the HTS-FSR configuration for compact rim-drive propulsion applications.