RU2763352C1 - Radial electromagnetic support for active magnetic bearing - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to bearing devices of rotary machines and can be used as part of various installations with a fast-rotating rotor, such as turbine units, centrifugal compressors and turbo expanders, electric motors and electric generators, and provides minimal magnetic coupling between the magnetization and control windings. The radial support for an active magnetic bearing (AMB) contains a radial electromagnet with a rotor in the form of a sleeve (2) made of soft magnetic ferromagnetic material placed on a rotating shaft (1) and a stator made in the form of a cylindrical housing (4) made of soft magnetic ferromagnetic material, inside which two stators (5) of regulating electromagnets are installed. At the ends of the sleeve (2) there are two rotors (3) of control magnets made in the form of cylindrical packages of sheets of electrical steel. The stators (5) contain magnetic cores made of electrical steel in the form of packages with four internal teeth, on which four control windings (10) are located. An insert (6) containing a magnetizing winding (7) and a two-coordinate capacitive gap sensor is installed between the stators (5) of the regulating electromagnets.

EFFECT: ensuring the possibility of using radial electromagnets of a special design with reduced requirements for the accuracy of manufacturing the elements of the supports and their mutual arrangement, reducing the power of the output cascades of the current regulators of the radial channels of stabilization of the AMB and the possibility of creating compact electronic modules placed in the structure of the supports or in close proximity to the supports.

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Description

The invention relates to bearing devices of rotary machines and can be used in various installations with a rapidly rotating rotor, such as turbine units, centrifugal compressors and turboexpanders, electric motors and electric generators.

Active magnetic bearings (AMPs) are known, which are widely used in modern superchargers of gas-pumping units, which include: a radial bearing, which includes a radial electromagnet, a sensor (sensors) of the radial position of the rotor and a safety bearing; radial - axial support, which includes elements of the radial support, as well as a double-acting axial electromagnet and a rotor axial position sensor; control cabinet with a set of cables. [Sarychev A.P., Vereshchagin V.P. Electromagnetic bearings for Gazprom // Elektrotekhnika. - M.: 1996. - No. 5. - S. 29-31].

The device of known AMP superchargers GPA is also described in the RF patent for the invention No. 2115835, publ. 1998 and in the patent for invention No. 2251033, publ. 2005

In known AMPs, the stator of radial electromagnets is a multi-pole magnetic circuit, in the form of a package of electrical steel, on the poles of which windings are placed, and the rotor is a cylinder, the outer side of which is made in the form of a package of electrical steel [Sarychev A.P. Development of electromagnetic bearings for a series of compressors for gas pumping units // Proceedings of NPP VNIIEM. - M.: 2009. - T. 110. - S. 3-10.].

The disadvantages of the known AMPs is that the design of the radial bearings predetermines the mismatch in the axial direction of the surfaces on which the holding forces act, and the surfaces along which the rotor deflection signal is generated by the position sensors. This discrepancy leads, firstly, to a significant tightening of the requirements for the accuracy of manufacturing and mutual layout of the structural elements of the rotor and stator of the radial support, and secondly, to the complication of algorithms for debugging the AMB circuits.

Known technical solutions to reduce the required power of the output amplifiers of the AMP current regulators by introducing the initial bias windings in the design of electromagnets [Zhuravlev Yu.N. Active magnetic bearings: Theory, calculation, application. - St. Petersburg: Polytechnic, 2003. - S. 60]. At the same time, with certain versions of the bias windings, there is an undesirable strong magnetic connection between the bias and control windings, which interconnects the processes of changing currents in the windings during the operation of the stabilization circuits.

The problem to which the invention is directed is to create a simple compact design of a radial support for AMBs of various machines with a rapidly rotating rotor, in which a minimum magnetic coupling between the bias and control windings is provided.

The technical result achieved by the invention consists in the possibility of using radial electromagnets of a special design with reduced requirements for the accuracy of manufacturing the elements of the supports and their relative position, reducing the power of the output stages of the current regulators of the radial channels for stabilizing the AMB and the possibility of creating compact electronic modules placed in the structure of the supports or in close proximity to the supports.

The technical result is achieved by the fact that in the radial support for an active magnetic bearing, containing a radial electromagnet and a two-coordinate capacitive gap sensor, the stator of the radial electromagnet is made in the form of a cylindrical housing made of magnetically soft ferromagnetic material, inside which two stators of control electromagnets are installed, containing magnetic circuits in the form of packages of electrical equipment. steel with four internal teeth, on which four control windings are located, and an insert containing a magnetizing winding and a two-coordinate capacitive gap sensor installed between the stators of the control electromagnets, and the rotor is made in the form of a sleeve made of magnetically soft ferromagnetic material placed on a rotating shaft, at the ends of which two rotors of control magnets are placed in the form of cylindrical packages of sheets of electrical steel, while the two-coordinate capacitive gap sensor is made in the form of a stator or with four rows or with three rows of conductive electrodes, two of them in the form of rings are current-collecting electrodes, and two rows in the form of isolated half-rings oriented relative to two radial axes are measuring electrodes, or with three rows of conductive electrodes, two of which are in the form of rings are current-collecting electrodes , and the third row in the form of four isolated segments oriented relative to two radial axes are the measuring electrodes.

The use of radial electromagnets of a special design, having magnetic circuits to accommodate bias windings and control windings.

The use of radial electromagnets of a special design, having magnetic circuits for placing the bias and control windings, provides a minimum magnetic coupling between the bias and control windings.

The integrated design of radial electromagnets with capacitive rotor position sensors additionally simplifies the algorithms for debugging the AMB stabilization circuits.

The use of initial bias in the AMB electromagnets further reduces the inductance of the control windings of the electromagnets, thereby increasing the speed of the AMB stabilization circuits.

The creation of compact AMB control modules and their placement directly in the support structure (or in close proximity) makes it possible to abandon the use of a control cabinet, which will additionally reduce interference in the AMB control circuits, as well as the effect of interference from the AMB on the surrounding equipment.

The use of a two-coordinate capacitive gap sensor, made in the form of a stator, or with four rows of conductive electrodes, in two of which the electrodes are current-collecting and made in the form of rings, and in the other two rows the electrodes are measuring and are isolated half-rings oriented relative to two radial axes, or with three rows of conductive electrodes, in two of which the electrodes are current-collecting and made in the form of rings, and the electrodes of the third row are measuring and made in the form of four isolated segments oriented relative to two radial axes, provides a minimal impact on the accuracy of measuring electromagnetic fields.

In addition, the expediency of using a capacitive gap sensor is motivated by the following advantages:

- sufficiently large diameters of the radial support structure allow the formation of large areas of capacitive sensor electrodes;

- the use of resonant settings of the gap measurement circuits allows to obtain a high sensitivity of the sensor (including micron measurement ranges);

- the sensor provides a small influence of temperature factors on the measurement accuracy, since the sensitive elements of the sensor are air capacitors;

- the design elements of the sensor do not require high precision of their manufacture, since the average gap is measured under the measuring electrodes, covering almost half (or a quarter) of the rotor diameter under each of the diametrically located electrodes.

The essence of the invention is illustrated graphically, where:

- in Fig. 1 shows a sketch of the design of the radial support;

- in Fig. 2 shows section A-A of FIG. one;

- in Fig. 3 shows an example of the design of an insert with a bias winding and a capacitive gap sensor;

- in Fig. 4 shows a functional diagram of the radial support stabilization system; The radial support (Fig. 1) contains a stator and a rotor. The rotor is a bushing 2 made of low-carbon steel (soft magnetic ferromagnetic material) placed on a rotating shaft 1. Two rotors 3 are placed on the bushing 2, which are cylindrical packages of sheets of electrical steel.

The stator housing 4 is made in the form of a hollow cylinder made of low-carbon steel (soft magnetic ferromagnetic material). Inside the stator housing 4, two stators 5 of control electromagnets and an insert 6 are installed, containing a magnetizing winding 7 and electrodes 8 of the stator of the capacitive gap sensor 9. The stator 5 of the control electromagnets contains a magnetic circuit in the form of a package of electrical steel with four internal teeth, on which four control windings 10 are located.

In FIG. 3 shows an example of the design of the insert 6 of a radial support with a four-row version of a two-coordinate capacitive gap sensor 9. A magnetizing winding 7 is located on the insulating frame of the insert 6. Inside the frame, four rows of conductive electrodes 8 are installed on the insulating rings, and the electrodes 8 in two rows are made in the form of rings and are current-collecting electrodes, and the electrodes in the other two rows are made in the form of isolated semi-rings oriented about two radial axes, and are the measuring electrodes. The electrodes 8 are connected by wires in the form of a bundle 11. The rotor of the capacitive sensor is the sleeve 2.

A three-row design of the capacitive gap sensor electrodes is possible, in which the middle row contains four electrically insulated electrode segments 8 oriented along the radial axes.

The forces that hold the rotor in the central position are created due to the electromagnetic interaction between the teeth of the stator 5 of the control electromagnets and their rotor 3 and are determined by the magnitude of the magnetic field induction in the gaps between the stator 5 and the rotor 3. In the proposed radial support, the magnetic field in the gaps of the control electromagnets is formed by two contours, - a bias circuit (a contour with dark arrows in Fig. 1) and a circuit of control electromagnets (a contour with white arrows in Fig. 1). So, for example, if in the section of the control electromagnet A-A (Fig. 2), the destabilizing force acts downward along the vertical axis, then the direction of the magnetic flux of the control electromagnets acts upward, which leads to an increase in the magnetic flux (and magnetic induction) in the gap of the upper tooth stator 5 and a decrease in the magnetic flux (and magnetic induction) in the gap of the lower tooth. As a result, the destabilizing force is balanced by a corresponding change in the electromagnetic forces in the gaps between the stator 5 and the rotor 3 of the control electromagnets. The four-pole design of the stators of the control electromagnets allows the stabilization of the rotor along two mutually perpendicular axes (X and Y). The rotor deflection signal is generated by a two-coordinate capacitive gap sensor 9.

The functional diagram (Fig. 4) reflects the composition and connections of the elements of the radial support stabilization system.

The measuring circuits of the channels for generating signals along the X and Y axes contain air capacitances of the current-collecting and measuring electrodes of the capacitive sensor 9, inductors 12, secondary windings of the transformer 13 and load resistances 14, forming a differential bridge. The primary winding of the transformer 13 is powered by the master oscillator 15. Adjusting the frequency of the master oscillator 15 to the resonance of the measuring circuit makes it possible to obtain high sensitivity of the gap measurement channels up to micron ranges.

When the rotor of the sensor 9 deviates, the gaps between the electrodes 8 change and on the load resistances 14 of the corresponding channels, AC voltage signals are emitted, the amplitude of which is proportional to the deviation of the sensor rotor 9 from the central position, and the voltage phase corresponds to the direction of the deviation. The selected signals from the corresponding measuring circuits are fed to the inputs of the phase-sensitive rectifiers 16, then the signals are fed to the dynamic correction filters 17 and to the power amplifiers 18, to which the windings 10 of the control electromagnets 5 are connected.

The bias winding 7 is connected to a DC source 19.

Radial AMP channels work as follows.

When the rotor deviates along any of the radial axes, for example, along the +X axis (Fig. 3) in a two-coordinate capacitive sensor, the air capacity under the upper measuring electrode increases, and under the lower measuring electrode decreases. This leads to the appearance of an error signal in the channel X of the stabilization of the rotor, which, after transformations in the phase-sensitive rectifier 16, the dynamic correction filter 17 and the power amplifier 18, changes the current in the windings 10 of the control electromagnets 5 so that the resulting force of the electromagnetic thrust brings the rotor to its original position.

Claims (3)

1. A radial support for an active magnetic bearing, containing a radial electromagnet and a two-coordinate capacitive gap sensor, characterized in that the stator of the radial electromagnet is made in the form of a cylindrical housing made of magnetically soft ferromagnetic material, inside which two stators of control electromagnets are installed, containing magnetic circuits made of electrical steel in the form of packages with four internal teeth, on which four control windings are located, and an insert containing a magnetizing winding and a two-coordinate capacitive gap sensor installed between the stators of the control electromagnets, while the rotor of the radial electromagnet is made in the form of a sleeve made of magnetically soft ferromagnetic material placed on a rotating shaft, at the ends of which there are two rotors of control magnets, made in the form of cylindrical packages of sheets of electrical steel. 2. The radial support according to claim 1, characterized in that the two-coordinate capacitive gap sensor is made in the form of a stator with four rows of conductive electrodes, and the electrodes in two of them are current-collecting electrodes made in the form of rings, and the electrodes in the other two rows are measuring electrodes made in the form of isolated semirings oriented relative to two radial axes. 3. The radial support according to claim 1, characterized in that the two-coordinate capacitive gap sensor is made in the form of a stator with three rows of conductive electrodes, and the electrodes in two rows are current-collecting electrodes made in the form of rings, and the electrodes of the third row are measuring electrodes made in the form of four isolated segments oriented relative to two radial axes.

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