We developed an axial gap permanent magnettype high temperature superconducting synchronous motor(PMHTSSM) at liquid nitrogen temperature. There are two distinctivedifferences between this motor and the conventional HTSmotors. The permanent magnet is applied to the field, iron coresand HTS wires are used as the armature. The motor has eight fieldpoles, and six armature windings. The armature is put betweenthe two fields. The field composes eight permanent magnets whichare arranged as a circle. Four poles share three armature coilsand there are two coils for every phase. The BSCCO wires, whichare applied to armature windings, work at the temperatures ofbetween 66 K and 70 K. The rated output is 400 kW at 250 rpm.It is known that superconducting wires have AC loss if they areoperated at alternating magnetic fields. That is why there are fewmotors developed with superconducting armature windings. Also,there is no report of motors applying HTS wires such as BSCCOwires to armature windings. Furthermore, this motor adopted therevolving field type structure, so the brushes were not needed andthe cooling system can be fixed. Also because of the axial-flux type,the structure of the cryostat can be simplified.
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