Mechanical and cryogenic design of a synchronous rotating machines with HTS pole-field magnets

We studied a high-temperature superconducting (HTS) synchronous motor assembled with melt-textured Gd-BaCu-O bulk pole-field magnets. The structure of a HTS motor is an axial gap type with neither brushes/slip rings nor iron core. The specific feature is that the rotor pole-field magnets of bulk are magnetized with pulsed current flow through vortex-type armature copper windings. The rotor pole bulks and armature coils are separately cooled down with liquid nitrogen. Cooling and magnetization of bulk pole field magnets are performed inside of the rotor. In order to attain high output as well as torque, single rotor plate with 8 bulks was substituted with a twinned rotor plate assembly with 16 bulks into triple layer armature units. In addition, we mention a possible larger scaled machine with exchange of a bulk with a multilayered double pancake coil (DPC) with Bi-2223 wire. The test product of this type of DPC showed up to 1.98 T at the centre of the coil surface at 30 K