| 摘要 |
PROBLEM TO BE SOLVED: To improve bearing rigidity when a rotor is stopped so as to prevent centrifugal whirling by switching a first integral control means and a second integral control means into each other on the basis of rotating speed of the rotor, and setting a gain suitably. SOLUTION: When an operation is started, a rotor 1 is lifted up slightly from an operating position, magnetic bearings 5, 6 are set in an operating state, and a permanent magnet 15 and a super conductor 17 are opposed to each other. At this time, a switch 29 is changed into a first integral control circuit 27 side, the rigidity of magnetic bearings 5, 6 is improved in order to increase its gain, and the positioning accuracy of the rotor 1 is improved. When the super conductor 17 is cooled and is set in a super conductive state, upper supporting force is generated on a super conductive bearing 2, and is balanced with a rotor weight so as to be supported near an operating position. In this state, an electric motor 7 is driven. When rotation of the rotor 1 exceeds changing rotating speed, the switch 29 is changed to a second integral control circuit 28 side, and its gain is reduced. It is thus possible to suppress centrifugal whirling of the rotor 1. |
