Electromagnetic Design of a REBCO Four-Pole Full-Pitched Armature Coil Composed of Trapezoidal Windings for Fully Superconducting Synchronous Motors

An electric propulsion system is one of the solutions to achieve low carbon dioxide emissions from aircraft. In this regard, a superconducting motor is being developed to achieve higher power density than conventional motors. Because a REBa2Cu3O7-sigma (REBCO) wire is difficult to bend freely owing to its tape shape, racetrack windings are often used for the armature coils of the superconducting motors. Although the output power can be increased for the same armature current by widening the armature winding pitch angle, the racetrack armature has only a small pitch of 30 degrees. A full-pitched armature with the maximum pitch angle has not been realized in past studies. Therefore, in this study, we propose an unprecedented configuration method of a four-pole full-pitched armature coil composed of trapezoidal windings. To investigate the advantages of the armature, we made a 2D cross-sectional model and determined torque using the finite element method of electromagnetic field analysis. Consequently, we verified that the trapezoidal four-pole armature had lower torque ripple and higher power density than the conventional two-pole racetrack armature. This study confirmed that the proposed novel armature had better characteristics than conventional ones. The armature can make the motor lightweight and low-noise.