Development of Reinforced Magnet Rings for High Speed Rotation. Magnet Rings for Super Conducting Magnetic Bearing in the Flywheel Type Energy Storage System.

The investigation of flywheel type energy storage system has been brisk in these days after discovered Y-based oxide superconductors according to the high potential fewer rotational loss for magnetic bearing even in the temperature (77K) of liquid nitrogen. Permanent magnet rings are applied to the rotational part, and high speed rotation is required to the magnet. The magnet itself is fragile material in the tensile stress, but it is strong enough in the compressive stress. Then authors designed the pre-compressed magnet rings by the multiple layer CFRP hoops. Three of the manufactured pre-compressed magnet rings rotated at the rotation speed of 33723rpm, 33472rpm and 33506rpm respectively at the rotation tests and the values of them were almost the same as the calculated value of 31300rpm.