Fabrication and test of superconducting generator with ring windings

Application of superconductivity to electric machines can bring about wider alternatives to the fundamental configuration compared with their conventional counterparts. As is well known, multi-phase electric machines can be easily realized with a ring-winding configuration. Because multi-phase machines are effective in generating smooth DC voltage with very low ripple, they are attractive for HVDC power transmission systems. The ring-winding configuration is also suitable for high-voltage design. Armature windings do not cross each other as in the conventional windings. The authors fabricated a small experimental superconducting generator with a superconducting ring-winding type armature. The armature is composed of 15 coils, that is, the number of phases is 15. It has also a superconducting field winding. The machine does not have iron core except for the outer magnetic shield made of laminated iron. A preliminary test was carried out. The output power is rectified by 15 sets of diode bridges. The voltage, current, and output power are presented. Also, the design and construction aspects of the machine are presented.