The invention relates to a rotary machine comprising a stator and a rotatably mounted rotor, with one or more magnetic field sensors arranged stationary relative to the stator at a radial distance from a stationary axis, at least one measuring device which configured to detect magnetic field changes with the aid of the aforementioned magnetic field sensors, a rotor which is configured to generate one or more electrical signals in each case, said signals having signal components which correspond to the rotor rotation frequency and to the distance between magnetic field sensor and rotor in each case, wherein a demodulator unit carries out a demodulation of signals generated by or derived from the magnetic field sensors, such that a signal is generated which corresponds to the distance between the rotor and the magnetic field sensor.

Unique systems, methods, techniques and apparatuses of active magnetic bearing control systems are disclosed. One exemplary embodiment is a power converter electrically coupled to an active magnetic bearing (AMB) having a plurality of windings, the power converter comprising a DC bus, two capacitors, a first leg, a second leg, and a controller. The capacitors are electrically coupled in series between the positive rail and negative rail, one capacitor being electrically coupled to the other capacitor at a midpoint connection. The first leg comprises a first semiconductor switching device and a first output node. The second leg comprises a second semiconductor switching device and a second output node. The first output node is electrically coupled to the midpoint connection by way of a first AMB winding and the second output node is electrically coupled to the midpoint connection by way of a second AMB winding.

A device for pumping blood, includes a housing having a distal end adapted to be coupled to a catheter, a proximal end having an outlet, and a tubular body extending between the distal and proximal ends along an axis. A rotor is rotatably disposed within the housing. A first magnetic bearing is operative to levitate the rotor along the axis within the housing. A second magnetic bearing controls a rotational frequency of the rotor. A third magnetic bearing controls a radial position of the rotor.

One embodiment describes a rotary machine system, which includes a stator with a first tooth, a second tooth, a third tooth, and a fourth tooth; a first electromagnet that includes a first electromagnet wire wrapped around the second tooth and the third tooth and that generates a first magnetic field to attract a drive shaft; a first integrated position sensor, which includes a first sensor wire that carries a first current wrapped around the first tooth and the second tooth; a second integrated sensor, which includes a second sensor wire that carries a second current wrapped around the third tooth and the fourth tooth; and a controller that determines current position of the drive shaft based at least on change of inductance of the first sensor wire and the second sensor wire, and that instructs the first electromagnet to adjust magnitude of the first magnetic field based at least in part on the current position.

A magnetic bearing includes a controller dividing a control region in two regions based on an individual difference between electromagnets regarding a correlation between two or more parameters among a current flowing through the electromagnets, a number of flux linkages, a gap width, magnetic energy, magnetic co-energy, electromagnetic force, and a parameter derived using these parameters. In a first control region with a small individual difference, the controller uses a control model common for all of the electromagnets. In a second control region with a large individual difference, the controller performs position control of a drive shaft using control models provided one for each of the electromagnets or one for each of a predetermined number of electromagnet groups.

In a state where part of a plurality of electromagnets (27) is controlled based on a control model built in advanced for a first control region (A1), and where position control of a drive shaft (13) is performed by controlling one or a group of the electromagnets (27) in a second control region (A2), an electromagnetic force of the electromagnets (27) controlled within the second control region (A2) is calculated based on an electromagnetic force of the electromagnets (27) controlled within the first control region (A1).

A magnetic bearing vacuum pump comprises: a first displacement signal generation section configured to amplify, by a resolution multiplying factor K of K>1, a displacement modulated wave signal modulated according to a displacement of the rotor from a predetermined position to generate a high-resolution displacement signal in a first displacement region including the predetermined position; a second displacement signal generation section configured to generate a low-resolution displacement signal in a larger second displacement region including the first displacement region; a selection section configured to select either one of the high-resolution displacement signal or the low-resolution displacement signal based on an unsteady-state response signal obtained by excluding a steady-state whirling displacement component from the high-resolution displacement signal or the low-resolution displacement signal; and a bearing control section configured to control the magnetic bearing based on the displacement signal selected by the selection section.

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.

A magnetic bearing supports an object to be supported in a noncontact manner by means of a composite electromagnetic force of first and second electromagnets. A processor-based controller causes a first current and a second current to be controlled according to the following equations, $\begin{array}{cc}{i}_1=\frac{g_0-\mathrm{ax}}{g_0}\left(i_b+i_d\right)& \left(1\right)\\ i_2=\frac{g_0+\mathrm{ax}}{g_0}\left(i_b-i_d\right)& \left(2\right)\end{array}$
where i.sub.1 is the first current flowing to the first electromagnet, i.sub.2 is the second current flowing to the second electromagnet, i.sub.d is a control current, i.sub.b is a bias current, g.sub.0 is a reference gap length, x is a displacement amount of the object to be supported with respect to a center position, and a is a predetermined correction coefficient.

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.