A magnetic bearing device comprises a stator (30) and a rotor (10) supported in the stator for rotation around a rotation axis (R). The rotor comprises at least one permanent magnet (21, 22) that is magnetized along the rotation axis. The stator comprises at least one closed magnetic core (31) that surrounds the rotor (10) and at least one radial bearing winding (32) arranged on the closed magnetic core (31) in a toroidal configuration. The at least one radial bearing winding is arranged to interact with a permanent magnetic field generated by the at least one permanent magnet to obtain a radial bearing force when current is supplied to the at least one radial bearing winding.

A bearingless hub assembly comprising a rim hollowed to receive a tube magnet, and magnets embedded around the circumference of the rim on both ends. The rim is capped by front and rear rim plates configured to hold the embedded magnets in place and fitted to receive respective circular magnets. Similar magnets in corresponding front or rear drive plate maintain space (i.e., levitation) vis-à-vis the front and rear rim caps by repelling each other, thus allowing the rim (and, as applied, a mechanically-attached tire assembly) to move freely with no friction. The front and rear drive plate carry forward and reverse electromagnetic actuators as well as forward and reverse levitation control units, power generators and speed sensors. These components mount 360 degrees around the circumference of the drive plates while the embedded magnets of the rim spin through when in motion.

A magnetic bearing control apparatus and a vacuum pump which do not require a displacement sensor, which enable control with high accuracy, and which are small and low cost. A rate of change (di/dt) that is a time derivative of a current value I.sub.m flowing through an electromagnet varies in accordance with a magnitude of a displacement of a gap between a target member and the electromagnet. The rate of change (di/dt) can be obtained by detecting a voltage value V.sub.s that is generated at both ends of an inductive element. Therefore, by detecting the voltage value V.sub.s, the magnitude of the displacement of the gap can be estimated by calculation. Inductive elements are connected in series to electromagnets and the voltage V.sub.s between the inductive elements is detected by the differential input amplifier. A single period of switching of a PWM switching amplifier is constituted by a current control period of the electromagnet and a displacement detection period for detecting the rate of change (di/dt). In addition, the displacement detection period is further constituted by a current increase period and a current decrease period which are certain periods of time. The current increase period and the current decrease period are equal to each other.

There is provided a controller for magnetic levitation equipment comprising a plurality of current source modules for connecting to at least one power supply for direct current, DC, and said current source modules comprising current channels for actuating coils of the magnetic levitation equipment, and a controller device connected to the current source modules by a control connection for controlling switching of electric current by the current source modules to the current channels. The current source modules combine discrete components for amplifying and switching electric current to the current channels into a single package. In this way, manufacturing and maintenance of the controller is facilitated, since manufacturing and maintenance may be based on the current source modules instead of discrete components, e.g. gate drivers, IGBTs, power mosfets and diodes.

A downhole-type system includes a rotatable shaft; a sensor that can sense an axial position of the shaft and generate a first signal corresponding to the axial position of the shaft; a controller coupled to the sensor, in which the controller can receive the first signal generated by the sensor, determine an amount of axial force to apply to the shaft to maintain a target axial position of the shaft, and transmit a second signal corresponding to the determined amount of axial force; and multiple magnetic thrust bearings coupled to the shaft and the controller, in which each magnetic thrust bearing can receive the second signal from the controller and modify a load, corresponding to the second signal, on the shaft to maintain the target axial position of the shaft.

A magnetic bearing control apparatus includes a plurality of output elements configured to generate electromagnetic force, a magnetic bearing configured to float a rotation shaft from a surface of the magnetic bearing based on the electromagnetic force generated by the plurality of output elements, at least one displacement sensor configured to sense a displacement of the rotation shaft, and a controller. The controller is configured to control a current supplied to the plurality of output elements, to control a position of the rotation shaft based on the current supplied to the plurality of output elements according to the displacement of the rotation shaft, and to determine a failure of the displacement sensor.

A compressor assembly is provided. Embodiments of the present disclosure generally relate to compressors used in chiller air conditioning systems for indoor spaces. The disclosed compressors have magnetic bearings that support rotating components. In one embodiment, the compressor comprises a partially segmented thrust bearing stator core. Additional systems, devices, and methods are also disclosed.

A centrifugal compressor includes a tubular shape casing extending in an axial direction, a motor stator fixed to an inside of the casing in a radial direction, a shaft disposed inside of the motor stator in the radial direction and extending in the axial direction, a motor rotor fixed to the shaft and facing the motor stator with a gap in the radial direction, a compression unit fixed to an end portion of the shaft on one side in the axial direction, a first thrust magnetic bearing disposed between the motor rotor and the impeller in the axial direction, and a second thrust magnetic bearing disposed on an other side in the axial direction relative to the motor rotor. A magnetic attraction force of the second thrust magnetic bearing toward the other side is larger than a magnetic attraction force of the first thrust magnetic bearing toward the one side.

A control system for controlling a magnetic suspension system includes sensors configured to produce position signals indicative of a position of an object to be magnetically levitated, and a controller configured to control, in accordance with the position signals, electric currents supplied to magnetic actuators of the magnetic suspension system to magnetically levitate the object. The control system includes a computing system configured to maintain and update a computational model of the magnetic suspension system based on identification runs where identification run signals are supplied to the magnetic actuators of the magnetic suspension system and responses to the identification run signals are detected from the sensors and/or the magnetic actuators. The computing system is configured to compare quantities related to the computational model to quantities related to the magnetic suspension system to reveal deviations from the expected operational conditions of the magnetic suspension system.

A bearingless hub assembly comprising a rim hollowed to receive a tube magnet, and magnets embedded around the circumference of the rim on both ends. The rim is capped by front and rear rim plates configured to hold the embedded magnets in place and fitted to receive respective circular magnets. Similar magnets in corresponding front or rear drive plate maintain space (i.e., levitation) vis-à-vis the front and rear rim caps by repelling each other, thus allowing the rim (and, as applied, a mechanically-attached tire assembly) to move freely with no friction. The front and rear drive plate carry forward and reverse electromagnetic actuators as well as forward and reverse levitation control units, power generators and speed sensors. These components mount 360 degrees around the circumference of the drive plates while the embedded magnets of the rim spin through when in motion.