The generation of highly efficient electric power is an extremely important technological development issue in protecting the global environment, and the realization of a highly efficient power generation system is always required. Furthermore, high-efficiency regeneration technology when braking drive motors used in transportation equipment, e.g., trains and automobiles, is also extremely important from the viewpoint of effective use of energy. Superconducting generators are one of the important candidates to solve the above problems. Our group has developed the High Temperature Superconducting Induction/Synchronous Machine (HTS-ISM) that consists of a three-phase stator winding and a squirrel-cage rotor winding [1], and reported the basic characteristics of it as a generator [2].
In this paper, we have developed a fully superconducting generator with a GdBCO stator and a BSCCO rotor. In particular, we set the minimum bending diameter of the GdBCO stator winding to 20 mm or less, and tried to verify the possibility of ultimate miniaturization. The critical currents of the 12 prototype GdBCO stator windings were measured and found to be 91-98 A at 77 K. As a typical result, we firstly succeeded in generation test at 77 K as shown in Fig., which the stator current is set to 30 A. It should be noted that the results show the possibility of stable generation in GdBCO stator with small bending diameter. In the presentation, more detailed test results, theoretical studies, and future prospects will be presented and discussed.

 [1] G. Morita, T. Nakamura and I. Muta, Supercond. Sci. Technol., 19(6) (2006) 473
[2] T. Nakamura et al., TEION KOGAKU (J. Cryo. Soc. Jpn.), 44(3) (2009) 112 (in Japanese)

Acknowledgements:
This work was supported by Grants-in-Aid for Scientific Research (B) (17H03218).

Fig. Generation test results of fabricated fully HTS-ISM (stator current: 30 A, 77 K)

Keywords: HTS-ISM, Fully superconducting generator, GdBCO stator, BSCCO rotor