Patent ID: 6984907

Claim:
A magnetic bearing apparatus comprising: an electromagnet having a coil for levitating a rotatable member by a magnetic force; and a control device configured to adjust a gain for levitation control of the rotatable member, said control device including: a displacement sensor operable to detect a levitated position of the rotatable member; a driver operable to supply a current to said electromagnet; a phase compensator operable to adjust the current to be supplied to said electromagnet based on a signal from said displacement sensor; a band-pass filter into which an output signal of said phase compensator is inputted; an amplifier operable to amplify an output signal of said band-pass filter at a predetermined amplification ratio; and an adder operable to add an output signal of said amplifier to an output signal of said phase compensator and supply an added signal to said driver, wherein said band-pass filter has a center frequency based on at least one of an actual rotation frequency of the rotatable member, a voltage, a current, and a frequency of a power source to supply electric power to a motor for rotating the rotatable member.