Abstract: A magnetic bearing device and a method of operation for such a device are provided. The device comprises a group (410) of electromagnetic actuators (411, 412, 413, 414). Each actuator is electrically connected to an amplifier unit (701). The actuators of a first subgroup are connected to a first common node (608), while the actuators of a second subgroup are connected to a second common node (609). The common nodes (608, 609) are connected either directly or through means like an additional actuator. Preferably the common nodes (608, 609) have no additional electrical connection to the amplifier unit. According to a special embodiment of the invention, each subgroup of actuators consists of only one single actuator and the common node has an electrical connection to the amplifier. Thus the device comprises two actuators in a series configuration connected to an H bridge. The common node may be connected to either of two different voltages.

Abstract: A magnetic bearing device (1) with an improved vacuum-tight electrical feedthrough through its housing (10) is disclosed. The feedthrough (30) comprises a flat connection element (31) such as a rigid or flexible printed circuit board extending through the wall of the housing (10), preferably all the way along an inner circumference of the housing. The connection element is sealed in a gas-tight manner to the housing. The element preferably has a central opening (36) for receiving the rotor shaft. Connections to the bearing units and sensors may be achieved by flat-ribbon cables (51) or flexprints. The sensors are preferably also implemented as printed sensors. Thus a very compact and cost-efficient magnetic bearing device can be obtained. An alternative embodiment uses a connection element on a side wall of the housing as a feedthrough to the bearing components.

Abstract: A rotor shaft (200) for a magnetic bearing device (1) is disclosed. The shaft comprises an inner portion on whose periphery a plurality of targets (240, 260, 280) separated by spacers (250, 270) are mounted. This is achieved exerting an axial pressing force (F, F?) to the peripheral parts, rather than applying a radial press fit. In this manner, a simplified construction, a higher stiffness and a higher stability at high rotational speed are achieved. Further disclosed is a rotor having a thrust disk (220) whose diameter decreases towards the periphery. This allows to use a larger thrust disk at a given rotational speed.

Abstract: A magnetic bearing device (1) for rotatably supporting a shaft (20) for rotation about a rotation axis (101) is disclosed. The device (1) comprises a first active radial bearing (5), one or more first radial displacement sensors (81), and an axial bearing (6, 7). At least a part of the axial bearing (6, 7) is disposed between the first active radial bearing (5) and the first radial displacement sensors (81) when viewed in an orthogonal projection onto the rotation axis (101). A vacuum pump including the magnetic bearing device (1) and a multiple-sensing unit (8) are also disclosed.

Abstract: A method and a controller for controlling a magnetic bearing device, in which a rotor is suspended for rotation around a shaft, are disclosed. Sensor signals are transformed to yield tilt displacement signals (S?x, S?y) which correspond to tilting displacements of the shaft in predetermined directions (x, y). From the tilt displacement signals (S?x, S?y), tilt control signals A?x, A?y) are derived; these are transformed to yield actuator control signals for driving electromagnetic actuators in the magnetic bearing device. According to the invention, tilting displacements for which the tilt vector rotates about the device axis (z) with a first predetermined sense of rotation are controlled separately from tilting displacements for which the tilt direction vector rotates about the device axis (z) with a second sense of rotation opposite to the first predetermined sense of rotation. In this way, control of nutation and precession can be achieved without influence from blade vibrations or shaft bending modes.

Abstract: A magnetic hearing device and a method of operation for such a device are provided. The device comprises a group (410) of electromagnetic actuators (411, 412, 413, 414). Each actuator is electrically connected to an amplifier unit (701). The actuators of a first subgroup are connected to a first common node (608), while the actuators of a second subgroup are connected to a second common node (609). The common nodes (608, 609) are connected either directly or through means like an additional actuator. Preferably the common nodes (608, 609) have no additional electrical connection to the amplifier unit. According to a special embodiment of the invention, each subgroup of actuators consists of only one single actuator and the common node has an electrical connection to the amplifier. Thus the device comprises two actuators in a series configuration connected to an H bridge. The common node may be connected to either of two different voltages.

Abstract: A magnetic bearing device (1) with an improved vacuum-tight electrical feedthrough through its housing (10) is disclosed. The feedthrough (30) comprises a flat connection element (31) such as a rigid or flexible printed circuit board extending through the wall of the housing (10), preferably all the way along an inner circumference of the housing. The connection element is sealed in a gas-tight manner to the housing. The element preferably has a central opening (36) for receiving the rotor shaft. Connections to the bearing units and sensors may be achieved by flat-ribbon cables (51) or flexprints. The sensors are preferably also implemented as printed sensors. Thus a very compact and cost-efficient magnetic bearing device can be obtained. An alternative embodiment uses a connection element on a side wall of the housing as a feedthrough to the bearing components.

Abstract: A rotor shaft (200) for a magnetic bearing device (1) is disclosed. The shaft comprises an inner portion on whose periphery a plurality of targets (240, 260, 280) separated by spacers (250, 270) are mounted. This is achieved exerting an axial pressing force (F, F?) to the peripheral parts, rather than applying a radial press fit. In this manner, a simplified construction, a higher stiffness and a higher stability at high rotational speed are achieved. Further disclosed is a rotor having a thrust disk (220) whose diameter decreases towards the periphery. This allows to use a larger thrust disk at a given rotational speed.

Abstract: A device for contact-less measurement of distances (10, 20) in multiple directions of an electrically conductive body (2, 22) comprises a plurality of inductive elements (1, 4, 7). At least one (1) of the plurality of inductive elements (1, 4, 7) is placed essentially around the body (2). The other inductive ele-ments or other magnetic field sensors (4, 7) are provided in the vicinity of said one inductive element (1). The device with these features allows integrating a multi axis inductive sensor on a single circuit board.

Abstract: A method and a controller for controlling a magnetic bearing device, in which a rotor is suspended for rotation around a shaft, are disclosed. Sensor signals are transformed to yield tilt displacement signals (S?x, S?y) which correspond to tilting displacements of the shaft in predetermined directions (x, y). From the tilt displacement signals (S?x, S?y), tilt control signals A?x, A?y) are derived; these are transformed to yield actuator control signals for driving electromagnetic actuators in the magnetic bearing device. According to the invention, tilting displacements for which the tilt vector rotates about the device axis (z) with a first predetermined sense of rotation are controlled separately from tilting displacements for which the tilt direction vector rotates about the device axis (z) with a second sense of rotation opposite to the first predetermined sense of rotation. In this way, control of nutation and precession can be achieved without influence from blade vibrations or shaft bending modes.

Abstract: A magnetic bearing device (1) for rotatably supporting a shaft (20) for rotation about a rotation axis (101) is disclosed. The device (1) comprises a first active radial bearing (5), one or more first radial displacement sensors (81), and an axial bearing (6, 7). At least a part of the axial bearing (6, 7) is disposed between the first active radial bearing (5) and the first radial displacement sensors (81) when viewed in an orthogonal projection onto the rotation axis (101). A vacuum pump including the magnetic bearing device (1) and a multiple-sensing unit (8) are also disclosed.

Abstract: A magnetic bearing supports an object such as a rotor in a stable, contactless position. The bearing has electromagnets, each associated with a respective current control means (e.g., amplifier or power switch), disposed to exert magnetic forces in various directions to levitate the rotor. A constant-current source feeds a constant (total) current the electromagnets in parallel. Sensing means detect movements of the rotor from the position and inform a controller that responds by controlling the respective current to each electromagnet to maintain the rotor in position.