| 摘要 |
PROBLEM TO BE SOLVED: To maintain a rotor in the magnetically levitated state until the speed is sufficiently reduced when a power failure occurs by switching a power supply of a magnetic bearing device from a normal power supply to a power supply based on the power generation of a motor upon detecting the power failure, and cutting off loads other than the magnetic bearing device from the power supply based on the power generation of the motor, by a load cut-off means. SOLUTION: A rotor 3 is rotated at high speed by a motor 6 while being in the magnetically levitated state by an electromagnet 4. The displacement of the rotor at this time is detected by a displacement sensor 5, and a control signal based on a displacement signal is outputted from a control device 17 to perform the position control of the rotor 3 by current control to the electromagnet 4. In this state, when the power failure of an AC power supply 10 is detected by a power failure detecting circuit 14, a change-over switch 16 is switched to the E-side, and a cut-off contact 14a is opened. A converter 13 is then connected to an electric path LAC by a bi- directional converter 11. Electric power is thereby generated by the motor (a generator) 6 through the rotor 3 keeping up its inertia rotation, and the electromagnet 4 is controlled with this electric power to maintain the rotor 3 in the magnetically levitated state until the speed is reduced.
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