Patent ID: 9093938
Filing Date: 2015-07-28
Classification: F04B,F04D,H02P

Abstract:
1. A magnetic bearing device comprising: a magnetic bearing unit configured to levitate and support a rotor shaft; a motor configured to rotate the rotor shaft; a motor drive circuit configured to drive the motor; a motor speed detector configured to detect motor speed of the motor; a current detector configured to detect current flowing through the motor drive circuit; a regenerative resistance configured to let regenerated current flowing from the motor drive circuit pass therethrough when the motor is braked; a motor driving current set value calculating unit configured to calculate a driving current set value of the motor depending on the motor speed detected by the motor speed detector so that energy consumption of the regenerative resistance becomes small when the motor rotates at high speed and increases as the motor speed decelerates to prevent temperature of the regenerative resistance from exceeding an allowable temperature when the motor is braked; a driving current adjuster configured to adjust a driving current so that the current detected by the current detector becomes the driving current set value calculated by the motor driving current set value calculating unit; a control element configured to control whether or not to pass current, the control element being connected in series with the regenerative resistance; a capacitor having one end connected to one end of the regenerative resistance, and the other end connected to the other end of the regenerative resistance through the control element; a voltage detector configured to detect voltage of the motor drive circuit; and a control element driving unit configured to drive the control element ON/OFF so that the voltage detected by the voltage detector becomes a set voltage value or smaller, wherein the driving current set value calculated by the motor driving current set value calculating unit is set at a driving current value I