A magnetic bearing controller for controlling a magnetic levitation motor, the magnetic levitation motor including: a rotor; a pair of electromagnets that causes the rotor to levitate by electromagnetic force; an auxiliary bearing that supports a rotating shaft of the rotor when the rotor is stopped; and a rotor position detector that detects the rotor's position in a levitation direction. The magnetic bearing controller includes an operation current generator that generates an operation current value corresponding to a deviation between a position command value and the rotor's position detected by the rotor position detector. The operation current generator is configured to give a predetermined initial value greater than 0 to the operation current value at a start of levitation for causing the rotor in a state where the rotating shaft of the rotor is supported by the auxiliary bearing to levitate and be positioned at a predetermined target position.

System for controlling at least one active magnetic bearing equipping a rotating machine comprising a rotor and a stator, at least one means for measuring the radial positions of the rotor as a function of the signal from at least one position sensor, and at least two control loops of the active magnetic bearing as a function of the radial positions of the rotor, each control loop of the magnetic bearing being provided with at least one synchronous filter as a function of the rotation speed, and an extended Kalman filter for determining the rotation speed of the rotor with respect to the stator receiving as input, from position sensors, measurements of radial position of the rotor and as a function of measurements of radial position of the rotor performed over a predetermined time at zero rotor rotation speed.

A magnetic levitation control device comprises: a control signal generation section configured to generate a first excitation current control signal based on current deviation information on the excitation current detection signal with respect to the current setting signal and a second excitation current control signal based on the current setting signal; and a selection section including a first switching section configured to select either one of the first excitation current control signal or the second excitation current control signal or a second switching section configured to select either one of a third excitation current control signal obtained by summation of the first excitation current control signal and the second excitation current control signal or the second excitation current control signal. The excitation amplifier is PWM-controlled based on the excitation current control signal selected by the selection section.

A first arithmetic section calculates a current rotation component phase value and a current rotation component amplitude value. A second arithmetic section calculates a displacement rotation component phase value and a displacement rotation component amplitude value. A third arithmetic section calculates a ratio between the amplitude value of the current rotation frequency component and the amplitude value of the displacement rotation frequency component. Feedback control is performed such that the current rotation component phase value is equal to a value obtained by addition of a phase value of 180 degrees to the displacement rotation component phase value and that the amplitude value of the current rotation frequency component is equal to a product of the displacement rotation frequency component and the ratio.

In a method for monitoring a magnetic bearing device for an electric rotating machine, a first pair of at least essentially diametrically opposed sensors and a second pair of at least essentially diametrically opposed sensors are arranged in offset relation about an angle. A distance is determined between each of the sensors and a body of rotation arranged inside the first and second pairs of sensors. A first average distance is determined from distance values of the first pair of sensors and a second average distance is determined from distance values of the second pair of sensors. A first change in the first average distance is captured and a second change in the second average distance is captured. The first and second changes are compared and a warning signal is outputted when a difference between the first and second changes exceeds a limit value.

A control method for a magnetic bearing includes following steps: acquiring a suspension stopping instruction for the magnetic bearing, and respectively applying a control current to one or more control coils of the magnetic bearing to subject a rotor to a vertically or obliquely upwards electromagnetic force, a vertical component of the electromagnetic force is less than the gravity of the rotor. A control device for a magnetic bearing is also disclosed, including a suspension stopping instruction acquiring unit and a control current applying unit. The control method and control device for a magnetic bearing can control a falling velocity of the rotor to be lower than that of the rotor being subjected only to the gravity, and have higher control efficiency.

A device (24) for controlling a magnetic bearing (22) includes an axis with two electromagnets (26, 28) diametrically opposed. The device (24) includes two power converters per axis of the magnetic bearing. Each power converter supplies one different electromagnet. The device includes eight power devices (40, 42, 44, 46, 48, 50, 52, 54) arranged in a first line (88) and a second line (90). Each of the first and second lines includes four power devices. A first set of four power devices (40, 42, 44, 46) are connected together to form a first power converter. A second set of four power devices (48, 50, 52, 54) are connected together to form a second power converter. Each of the first and second lines (88, 90) includes two power devices (40, 42, 44, 46) of the first set and two power devices (48, 50, 52, 54) of the second set.

A magnetic levitation control device comprises: a control signal generation section configured to generate a first excitation current control signal based on current deviation information on the excitation current detection signal with respect to the current setting signal and a second excitation current control signal based on the current setting signal; and a selection section including a first switching section configured to select either one of the first excitation current control signal or the second excitation current control signal or a second switching section configured to select either one of a third excitation current control signal obtained by summation of the first excitation current control signal and the second excitation current control signal or the second excitation current control signal. The excitation amplifier is PWM-controlled based on the excitation current control signal selected by the selection section.

In a method for monitoring a magnetic bearing device for an electric rotating machine, a first pair of at least essentially diametrically opposed sensors and a second pair of at least essentially diametrically opposed sensors are arranged in offset relation about an angle. A distance is determined between each of the sensors and a body of rotation arranged inside the first and second pairs of sensors. A first average distance is determined from distance values of the first pair of sensors and a second average distance is determined from distance values of the second pair of sensors. A first change in the first average distance is captured and a second change in the second average distance is captured. The first and second changes are compared and a warning signal is outputted when a difference between the first and second changes exceeds a limit value.

In a method for monitoring a magnetic bearing apparatus a first pair of at least essentially diametrically opposed sensors and a second pair of at least essentially diametrically opposed sensors are arranged in offset relation about an angle. A distance of each of the sensors from a rotating body arranged inside the first and second pairs of sensors is determined by temporal averaging of a plurality of distance measurements. The distances of the sensors from the rotating body are compared and a warning signal is outputted when a difference in the distances exceeds a limit value.