Magnetic bearing device and compressor

A magnetic bearing device, comprising:

• a magnetic bearing that has first and second electromagnets opposed to each other with an object to be supported interposed therebetween and supports the object to be supported in a noncontact manner by means of a composite electromagnetic force of the first and second electromagnets;
• and
• a processor coupled with a memory storing a program which, when executed by the processor, causes a first current and a second current to be controlled according to the following equations,
• i
• 1
• =
• g
• 0
• -
• ax
• g
• 0
• ⁢
• (
• i
• b
• +
• i
• d
• )
• (
• 1
• )
• i
• 2
• =
• g
• 0
• +
• ax
• g
• 0
• ⁢
• (
• i
• b
• -
• i
• d
• )
• (
• 2
• )
• where i1 is the first current flowing to the first electromagnet, i2 is the second current flowing to the second electromagnet, id is a control current corresponding to a current component varying according to a displacement of the object to be supported in the opposed direction of the first and second electromagnets, ib is a bias current corresponding to a current component indicating a predetermined current value, g0 is a reference gap length corresponding to a gap length between the object to be supported and the first and second electromagnets at the time when the object to be supported lies at a center position between the first and second electromagnets, x is a displacement amount of the object to be supported with respect to the center position in the opposed direction of the first and second electromagnets, and a is a predetermined non-zero correction coefficient.