A study on high temperature superconducting (HTS) double pancake field coils for HTS synchronous machines applications

The High Temperature Superconducting (HTS) synchronous machines having compact size, lower weight and higher efficiency are finding more and more applications in various industrial domains. The most promising topology for such machines is copper winding based stator along with HTS winding based rotor. The rotor field winding of such HTS synchronous machine can be realized with racetrack shaped double pancake type HTS coils. These HTS coils can be designed for unprecedentedly higher ampere-turns and magnetic flux densities. Worldwide limited number of such double pancake type HTS coils has been developed for synchronous machine applications. A brief account on these developments have been presented in this paper along with various design aspects and considerations needed to be followed during design and development stage of such coils. In line with this, a prototype double pancake HTS coil has been developed and tested and the results are also presented in this paper.