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

Abstract

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.Index Terms-HTS motor, Gd-Ba-Cu-O bulk, pulse magnetization, double pan-cake coil with Bi-2223 wire

Pulsed-field magnetization of bulk HTS magnets in twinned rotor assembly for axial-type rotating machines

“…Figure 6 shows a successful magnetization of eight-pole field magnets. As the present motor performance as the torque is 212 N m for 16 kW, 720 rpm operation with the maximum trapped field of 0.7 T [5,6]. It is necessary to improve the efficient pulsed magnetization technique of the HTS bulk field magnet with armature coils.…”

Recovery of trapped field distribution around a growth sector in a Gd–Ba–Cu–O HTS bulk with pulsed-field magnetization

“…The PFM processes a penetration of applied external pulsed magnetic field into the bulk HTS body and lets the mobile flux be pinned in the vicinity of the doped pinning centres [6]. As a pole-field magnet, it has been clearly proved that the PFM method is a practical method for applications to HTS bulk rotating machines [7]. However, using the PFM process, the trapped magnetic flux is reduced compared to that with a conventional field cooling using a different superconducting magnet.…”