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 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 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 refrigerator according to the present invention includes: a cooling part for cooling an object to be cooled through heat exchange with a refrigerant; an expander-integrated compressor including a compressor for compressing the refrigerant and an expander for expanding the refrigerant integrated therein; and a refrigerant circulation line configured to circulate the refrigerant through the compressor, the expander, and the cooling part. The compressor includes a low-stage compressor, a middle-stage compressor, and a high-stage compressor disposed in series in the refrigerant circulation line. The expander-integrated compressor includes: the middle-stage compressor; an expander for adiabatically expanding and cooling the refrigerant discharged from the high-stage compressor; a first motor having an output shaft connected to the middle-stage compressor and to the expander; at least one non-contact type bearing, disposed between the middle-stage compressor and the expander, for supporting the output shaft of the first motor without being in contact with the output shaft; and a casing for housing the middle-stage compressor, the expander, and the at least one non-contact type bearing.

An active magnetic bearing of a shaft, which shaft can be rotated about an axis, includes a magnetically conductive main body, which is arranged in a stationary manner and which surrounds the shaft. Partial bodies are arranged one behind the other axially at an axial distance between adjacent partial bodies and form the magnetically conductive main body. A winding system is arranged in grooves of the magnetically conductive main body.

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 magnetic fluid seal includes an outer cylinder member with a heat barrier that internally houses a rotating shaft extending from a housing of a fluid machine and includes an attachment portion to be attached to the housing, magnetic pole members that are disposed around the rotating shaft housed in the outer cylinder member and form a magnetic circuit, and sealing films that are magnetically connected to the magnetic circuit, are respectively disposed between the magnetic pole members and the rotating shaft, are made of magnetic fluids, and are formed in an axial direction.

A fluid module includes a fluid rotor configured to rotatably drive or be driven by fluid produced from a wellbore. A first shaft is coupled to the fluid rotor. The first shaft is configured to rotate in unison with the fluid rotor. A thrust bearing module includes a thrust bearing rotor. A second shaft is coupled to the thrust bearing rotor. The second shaft is configured to rotate in unison with the thrust bearing rotor. The second shaft is coupled to the first shaft. An electric machine module includes an electric machine rotor. A third shaft is coupled to the electric machine rotor. A third shaft is configured to rotate in unison with the electric machine rotor. The third shaft is coupled to the second shaft. The third shaft is rotodynamically isolated from the first shaft and the second shaft.

A device includes a rotor to rotate about a longitudinal axis, a magnetic bearing actuator, and an axial gap generator including a stator assembly adjacent to the rotor, the axial gap generator to generate an amount of power as a function of a gap spacing between the stator assembly and the rotor, the gap spacing parallel to the longitudinal axis, and the axial gap generator to supply the amount of power to a control coil of the magnetic bearing actuator.

A system and modular compressor for raising the pressure in production gas is disclosed, wherein in a set of compressor modules each second module is a rotor module carrying an impeller driven in rotation relative to an adjacent stationary module, a rotor module and a stationary module in combination providing a compressor stage in which production gas is accelerated through a flow duct that passes an interface between the rotor module and the stationary module, wherein at the interface at least one bearing for axial and/or radial load is provided for journaling the rotor module on the stationary module. The at least one bearing is a gas bearing, wherein a passage is arranged in the stationary module to lead an extracted portion of production gas at raised pressure from the compressor to the gas bearing(s).