Comparison of critical current and AC loss of 15 MVA superconducting machines with different topologies

Abstract

Superconducting motors, characterized by their high current-carrying capacity, facilitate the exploration of varied topological designs beyond those possible with traditional motors. Nevertheless, many studies fail to account for the anisotropic properties of superconducting coils, resulting in inaccurate analyses of critical currents and AC losses. This paper introduces a simulation model for 15 MVA superconducting motors employing the H-formulation, which methodically assesses how the configurations of stator and rotor cores impact motor performance. The magnetic behavior of the rotor core, defined through the $B$-$H$ curve derived via the ring sample method, is integrated into the model, enhancing its accuracy. The results reveal that incorporating rotor back core not only reduces the use of superconducting tape but also bolsters the magnetic field adjacent to the coil, thus improving its current-carrying capacity. This approach maximizes output capacity with minimal variations in excitation current. In contrast, including magnetic teeth in the stator curtails superconducting tape consumption and AC losses, it introduces space harmonics that elevate cogging torque. The study determines that the optimal topology combines stator and rotor back core while excluding magnetic teeth in both windings. Finally, a prototype of real-scale racetrack a high-temperature superconducting winding is manufactured, and the critical current within the different core structures is measured to validate its performance.