A Design Study on HTS Halbach Array for Field Coil of 40 MW Ship Propulsion Motor

A 40 MW ship propulsion motor was designed with a high temperature superconductor coil Halbach array. The Halbach array was applied to the field coil of the motor for further performance improvement. We performed our design study on two different motor types: Halbach array inner positioned field coil motor (HIFM) and Halbach array outer positioned field coil motor (HOFM). The design for the field coil was optimized with NSGA-II. Final models were selected for HIFM and HOFM, respectively, and to estimate the effect of the HTS coil Halbach array, they were compared with reference motors with a conventional field coil. Both HIFM and HOFM showed a 7% increase in the flux to the air-gap. As the shielding effect of the Halbach array in HOFM reduced by 70% the weight of the iron shield, HOFM showed comparable weight compared to the conventional inner field coil motor. This overcomes the problem of the low power density of the outer field coil motor. With the Halbach array field coil, a design topology having the stationary field coil on the outer side of the motor would be realized with a simplified cooling structure while maintaining the light shield weight.