Control circuit system for magnetic bearing

PURPOSE:To enable stable control, with a less number of parts, over a magnetic bearing which is provided with a control coil and supports a rotating body, by feeding back a signal produced by integrating a current component flowing through the control coil. CONSTITUTION:To support a rotating body with a magnetic bearing comprising a permanent magnet sensor 17 and a control coil 11, the position of the rotating body is detected by a displacement sensor 17 and a current is applied to the control coil 11 through the action of a displacement signal processing circuit 18, a phase compensation circuit 19 and a power amplification circuit 20 depending on the output of the sensor 17. When the rotating body is not in such a position that the rotating body is balanced to the load, the current keeps flowing through the control coil 11. At that time, the current is detected by a current detection circuit 7 and integrated by an intergration circuit 9 and fed back to the displacement signal processing circuit 18. The fed back signal is synthesized with the rotating body displacement signal from the sensor 17. The synthesized signal is applied to the phase compensation circuit 19 to perform phase compensation.