AN EXPERIMENTAL GENERATOR USING HIGH-TEMPERATURE SUPERCONDUCTING QUASI-PERMANENT MAGNETS

An experimental axial gap generator, with a 6 inch diameter rotor and quasi-permanent HTS magnets, was tested. A variable speed motor was us ed to rotate the rotor above a stater composed of copper wire wound in an 8 pole 3 phase configuration. The rotor and stater were both run i n liquid nitrogen. A 3 phase variable resistor bank was the generator load, The HTS magnets were YBCO, each 2 cm in diameter and 1 cm thick, melt textured using a SmBCO seed, containing 60% excess Y, and about 1%Pt, They were not irradiated, and could trap maximum fields of 3500- 4000 G. First, the HTS magnets were field cooled in a field of approxi mately 2200 G, provided by the stater while carrying 25 Amperes. The H TS magnets trapped about 1800 G, In this configuration, the generator was run for about one hour at speeds up to 2000 RPM, and developed a m aximum power output of 33 Watts. Next the HTS magnets were warmed, and then zero field cooled; In this case, activation was accomplished by a similar to 15 ms pulse on the stater, providing 5000G of pulsed fiel d. The HTS magnets trapped about 2600 G. The generator was then run fo r about 1 hour at speeds up to 2265 RPM, and developed a maximum power output of just under 100 Watts.