HTS motor shape optimization for its maximum critical current of the field winding

Superconducting motors have high efficiency as well as reduced size and weight. In superconducting motors, the field winding is composed of HTS tapes (Bi-2223) without any iron core because of magnetic saturation, and the current in the field winding is limited by the maximum magnetic field in the field winding. To enhance the performance of superconducting motor, we need to maximize the critical current of field winding as much as possible. This paper introduces the shape optimization method with the constraint of HTS characteristic (I/sub c/-B curve), and proposes a shape that improves the critical current of the field winding. Finite element analysis and discrete sensitivity approach are used for calculating the magnetic field of coil and shape optimization.