A control node (3) for controlling a magnetic bearing is configured to control a servo axis of the bearing. The control node includes a synchronization module (15) configured to generate a synchronization signal (SYNC) upon receipt of synchronization information (INFO). At least one internal clock (17, 18) is configured to be synchronized with the synchronization signal (SYNC).

A tool includes a device including a housing and a rotor, the rotor to rotate about a longitudinal axis, and an axial gap generator including a stator assembly positioned adjacent to the rotor. The axial gap generator generates a voltage signal as a function of a gap spacing between the stator assembly and the rotor, the gap spacing being parallel to the longitudinal axis.

A method of measuring a center error between bearings includes disposing both sides of a rotation shaft on inner circumferential surfaces of a magnetic bearing and a backup bearing, applying current to the magnetic bearing to produce movement of the rotation shaft, determining a contact point between the rotation shaft and the backup bearing according to movement of the rotation shaft, determining a final target value using the contact point and predetermined position information of the magnetic bearing, determining a magnetic center of the magnetic bearing through the final target value, comparing the magnetic center of the magnetic bearing and a mechanical center of the backup bearing to determine a center error, and aligning the magnetic center of the magnetic bearing and the mechanical center of the backup bearing based on the determined center error.

An improved flywheel system for storing energy and providing the stored energy includes a rotor on a centrally located shaft. The shaft is positioned through support bearings. A magnetic off-loader provides a magnetic force to move the shaft axially in regard to the bearings. A feedback control system, provided to reduce bearing loads on the bearing, comprises a sensor mounted in a bearing housing positioned to measure the distance of a gap between a top end of the shaft and a lower surface of the sensor. In response to changes in the distance the sensor sends an electrical signal to a controller which in turn provides variable electric current to the magnetic off-loader which then provides a magnetic lifting force to the rotor on the shaft to minimize bearing load.

A power supply circuit supplies a current from a DC voltage source to first and second actuator coils to support an object in a non-contact manner by electromagnetic force. The power supply circuit includes a first leg connected to the DC voltage source, and a control unit. The first leg has first upper and lower arm switching elements connected in series. The control unit turns the switching elements on and off to control the current supplied to the actuator coils. A midpoint between the switching elements is connected to a connection point between the actuator coils. A freewheeling diode is provided for each of the switching elements in parallel. The control unit performs control so that the current flows through the first actuator coil in a direction toward the connection point, and the current flows through the second actuator coil in a direction coming out of the connection point.

A downhole-type system includes a rotatable shaft, a downhole-type magnetic bearing coupled to the rotatable shaft, a downhole-type sensor, a surface-type controller, and a surface-type amplifier coupled to the magnetic bearing. The magnetic bearing can control levitation of the rotatable shaft. The downhole-type sensor can detect a position of the rotatable shaft in a downhole location and generate a first signal based on the detected position. The surface-type controller can receive the first signal, determine an amount of force to apply to the shaft, and generate a second signal corresponding to the determined amount of force. The surface-type amplifier can receive the second signal, amplify the second signal to a sufficient level to drive the magnetic bearing to apply force to the rotatable shaft to control the levitation of the rotatable shaft at the downhole location, and transmit the amplified second signal to the magnetic bearing.

A device (21) for controlling a spindle of a grinding machine (1) is disclosed. The spindle includes a rotor (5) supported by two radial magnetic bearings, one axial bearing, and a grinding wheel (6). The device includes a storage means (22) for storing control coefficients of the magnetic bearings. The device includes a means for determining a type of the grinding wheel and a type of the rolling bearing ring. A selection means (23) selects control coefficients associated with the determined types of grinding wheel and of rolling bearing ring from among the control coefficients stored in the storage means. The device also includes a means (23) for controlling the radial and axial magnetic bearings. Said means controlling the radial and axial (12) magnetic bearings on the basis of the control coefficients of the determined types of grinding wheel and of rolling bearing ring.

A magnetic bearing device comprises: a magnetic bearing configured to magnetically levitate and support a rotor rotatably driven by a sensor-less motor; a detector configured to detect displacement from a levitation target position of the rotor to output a displacement signal; a signal processor configured to compensate, based on motor rotation information from a motor controller of the sensor-less motor, for the displacement signal to reduce a vibration component of electromagnetic force of the magnetic bearing; and a current controller configured to generate control current of the magnetic bearing based on the displacement signal having been processed in the signal processor.

A motor controller and methods for operating a motor are described herein. The motor controller includes a high-frequency (HF) inverter having a direct current (DC) input stage and an alternating current (AC) output stage, the HF inverter operable at a switching frequency to generate a three-phase output having a fundamental frequency. The motor controller also includes a differential mode (DM) filter coupled in series with the output stage of the HF inverter and having a resonant frequency less than 10% of the switching frequency, the DM filter configured to reduce harmonic components of the three-phase output and generate a first filtered output. The motor controller further includes a common mode (CM) filter coupled in series with the DM filter, the CM filter configured to filter the first filtered output to generate a second filtered output having a reduced CM voltage to operate the electric motor with a reduced bearing current.

A tool includes a device including a housing and a rotor, the rotor to rotate about a longitudinal axis, and an axial gap generator including a stator assembly positioned adjacent to the rotor. The axial gap generator generates a voltage signal as a function of a gap spacing between the stator assembly and the rotor, the gap spacing being parallel to the longitudinal axis.