| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetic bearing device capable of preventing excessive amplitude of a rotor in changing feedback gain. SOLUTION: A magnetic bearing type turbo molecular pump must experience a critical speed (rotation speed n2) from the rotor rotating start to a stationary rotation. From the rotor rotating start to a rotation speed n3, the magnetic bearing is controlled at a control gain G1 of which rotation speed n1 is a critical speed. When the rotation speed exceeds n4, it is controlled at a regular control gain G2. In a rotation speed range n3≤n≤n4 as a gain change-over zone, the control gain G is continuously varied from G1 to G2 in response to the increase of the rotation speed. As a result, the excessive amplitude of the rotor in changing the gain can be prevented. COPYRIGHT: (C)2004,JPO&NCIPI
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