Magnetic bearing control device

A magnetic bearing control device for controlling a magnetic bearing for supporting a rotor in non-contact manner, and a motor for rotating said rotor and capable of generating an electric power with the rotation of said rotor, comprising:

• a magnetic tearing drive controller which drives and controls said magnetic bearing;
• a motor drive circuit including an inverter for driving said motor, a regenerative circuit for supplying a regenerative electric power generated by said motor to said magnetic bearing drive controller, and switch portion for selectively switching the connection of said inverter and said regenerative circuit to said motor;
• an inverter controller which controls said inverter;
• and
• an over-speed detection circuit for detecting a number of revolutions of said rotor and outputting an over-speed detection signal when the detected number of revolutions is greater than or equal to a preset number of revolutions;
• wherein said motor drive circuit performs a switching operation of the switch portion to separate the inverter from said motor, and connect the regenerative circuit to said motor, when the over-speed detection signal from said over-speed detection circuit is input.