DE102006018267A1 - Active magnetic bearing controlling method, involves distributing electromagnetic parts and generating force and/or torsional moment for absorbing vibrations and for balancing bearings of ferromagnetic part e.g. rotor - Google Patents

Abstract

In a method for controlling active magnetic bearings and a method-controlled magnetic bearing device in which the electromagnetic parts are spatially distributed, and by controlling the individual bearing windings distributed on a ferromagnetic part (rotor) forces and / or torques can be generated which are necessary for the bearing of the ferromagnetic part (rotor), additional forces and / or torques are generated in addition to the bearing forces by specifically setting the winding currents. These additional forces and / or torques can be used to implement active vibration damping, to compensate for a bend, to take on a further bearing function or to support further bearing devices (FIG. 9).

Description

The The invention relates to a method for driving active magnetic bearings and a magnetic bearing device, wherein the electromagnetic parts the magnetic bearing device spatially are distributed and by controlling the individual bearing windings distributed acting on a ferromagnetic part forces generated become.

Context of invention

When example for an electromagnetically to be stored part is to be further in a spindle by means of two radial and one axially acting Electromagnet device mounted rotor are used, without that the invention would be limited thereto in any way. In addition, can an engine for be installed the drive of the rotor.

at Magnetic bearings is basically distinguished between active and passive magnetic bearings. While at passive magnetic bearings, the magnetic forces usually only by permanent magnets can be generated in active magnetic bearings by changing the winding currents the magnetic forces be varied. In the latter magnetic bearings, the position of the rotor detected, and the winding currents for generating the bearing forces are calculated and output by a control device.

Magnetic mounted rotors offer opposite Conventionally mounted rotors, for example, roller bearings Rotors, significant advantages. Since no mechanical contact between Rotor and stator is made, no wear occurs, and there is no lubrication needed. This is why magnetically supported rotors are very well suited for work in a vacuum or in a cleanroom, but also in applications Use where the rotor rotates at high speeds. In addition, can the rotor can be freely moved within the air gaps of the magnetic bearings. By suitable driving of the magnetic bearings, the rotor can be positioned or be moved on specifiable tracks. For example, at the cutting production of mold holes the rotor angle synchronous and nevertheless guided with high precision on a given path.

State of technology

at every cutting-edge production, such as fine turning bending vibrations of the rotor severely negative on the quality of machining. By Bending vibrations are the for needed the position control Measured values for the position of the rotor is distorted, whereby the positioning accuracy of the tool deteriorates or the positioning becomes even unstable. Commissioning a magnetically supported rotor and the optimization of a manufacturing process in terms of technological parameters are made significantly more difficult. In the rotor can Bending and bending vibrations, inter alia, by the operations on the tool but also be excited by the magnetic storage itself.

In the DE 100 34 017 A1 and DE 103 53 101 B4 For example, control methods for magnetic radial bearings of a ferromagnetic rotor are described using distance sensors, without the problem of bending or vibra tion behavior of the rotor would have been given special attention.

In the published patent application DE 198 37 624 A1 already a tool spindle with integrated vibration damping is presented. However, the rotor is mounted by means of rolling bearings. Only by the built-in motor in addition to the drive torque radially acting forces are generated, which are used to dampen vibrations occurring.

technical problem

With Help additional Sensors can occurring vibrations and bends of a rotor can be measured. To dampen the detected vibrations or compensate for bends to be able to have in addition to Storage forces or torques are impressed on the rotor.

Such compensation forces could for example, by additional radial electromagnetic bearings are generated. This extra Magnetic bearing would however a larger length of the Rotors condition. For a longer one Rotor, however, the natural frequencies are lower, which is synonymous with a deterioration of the rotor dynamic properties. Furthermore go up by additional Stock the costs.

epiphany the invention

Of the The invention is therefore based on the object, a method for Activation of active magnetic bearings and a corresponding magnetic bearing assembly indicate, without additional active magnetic bearings and without the use of rolling bearings an active damping of vibrations and / or compensation of bends of a ferromagnetic part (rotor) is achieved.

According to the invention is at an actively magnetically mounted ferromagnetic part (rotor) a vibration damping and / or bend compensation integrated, without additional To claim space in the spindle by the spatial Distribution of active bearing magnets in certain magnetic bearing designs is exploited in addition to to the bearing forces also compensation forces or -drehmomente to produce. Be the spatially distributed bearing magnets individually controlled, so can the individual magnetic forces be set, which in suitable bearing designs bearing forces and additional torques be generated. If the bending or oscillation of the rotor is detected, so can by selective adjustment of the individual magnetic forces a vibration damping and / or a bend compensation can be achieved. The capture The bend can be done directly by attaching sensors or indirectly for example, by evaluating the coil inductances of exist existing active magnetic bearing, in addition to the Position measured values of the sensors are taken into account for the position control can be. Further Features of the invention are disclosed in the claims.

The Invention is based on embodiments be explained in more detail.

In the associated Drawings show:

1 schematically a magnetically supported shaft,

2 schematically the structure of a thrust bearing half,

3 schematically the interconnection of the bearing windings of a thrust bearing to a three-phase system,

4 schematically the interconnection of the bearing windings of a thrust bearing to a star-connected three-phase system,

5 schematically a radial bearing, constructed as a four-phase unipolar bearing,

6 schematically a radial bearing, constructed as a three-phase unipolar bearing,

7 schematically a radial bearing, constructed as a purely electromagnetic homopolar bearing,

8th schematically the measurement of the bending of a rotor ( 8a ) not bent rotor, 8b ) curved rotor),

9 schematically acting on the rotor forces ( 9a ) not bent rotor, 9b ) curved rotor with compensation) and

10 a block diagram of the functional blocks for deflection compensation according to the invention and / or vibration damping.

1 shows schematically the structure of an electromagnetically mounted rotor 4 , For storage of the rotor 4 become two radial bearing devices 1 and 2 in the end regions of the rotor 4 and one between the radial bearing devices 1 . 2 arranged axial bearing device 3 used. (The choice of bearing arrangement is free, the in 1 shown bearing arrangement is exemplary.) In the in 1 For the purpose of radial support, two three-phase pure electromagnetic bearings are used as examples 1 . 2 used. In the magnetic thrust bearing 3 can be described by two stators to be described later (for example, two electromagnets), located on both sides of a fixed to the rotor 4 connected bearing disc of the thrust bearing 3 bearing forces are generated. In addition, a motor to such a magnetically mounted rotor 4 be grown by the rotor 4 is driven.

In 2 is one half of a thrust bearing 3 presented in so-called temple design. (The submitted The invention is not limited to the embodiment with six magnetic poles. The procedure presented here is applicable for magnetic bearings with one of six different number of magnetic poles.) The thrust bearing 3 consists of two annular stators 5 on both sides of a bearing disc 7 , The stators 5 have pole faces. The poles are of bearing windings 6 surround. By currents in the bearing windings 6 become magnetic fluxes in the stators 5 , in the air gap and in the bearing disc 7 generated, whereby a bearing disc 7 attractive force arises. By targeted control of the individual bearing windings 6 For example, different forces can be generated on each pole face, whereby both an attractive, axially acting force and a torque about a radially extending axis can be generated. The angular position of this imaginary axis can be controlled by targeted control of the individual bearing windings 6 also be adjusted.

By suitable interconnection of the bearing windings 6 Channels can be saved on the power control device, however, depending on the Verschaltungsvariante different driving methods arise. In 3 and 4 are two advantageous Verschaltungsvarianten for each bearing half of the thrust bearing 3 shown. In 3 are six bearing windings 6a to 6f shown according to the drawing on the annular stator 5 are divided. Two bearing windings each ( 6a . 6b ) 6c . 6d ) 6e . 6f ) form a pair of windings, just so that the magnetic flux generated by a current in a pair of windings forms a mesh (indicated by the comparison of the tap of the bearing winding and the current direction marked with the dot). It follows that in each case by a current, i ₁ , i ₂ or i ₃ , in each case a force in the axial direction and a torque about an imaginary radial axis are generated in a pair of windings. The star connection of the winding pairs restricts the method according to the invention only to the extent that in addition the algebraic condition i ₁ + i ₂ + i ₃ = 0 must be taken into account in the design of the drive (see DE 103 53 101 B4 ).

In 4 is a particularly advantageous Verschaltungsvariante a thrust bearing 3 presented in temple style with six bearing windings. Two bearing windings each 6a . 6b ) 6d . 6e ) 6c . 6f ) are connected in series, but such that one of the pairs of windings ( 6c . 6f ) When energized (i _w ) an axial force is generated without generating a torque about an imaginary radial axis. By a current i _u or a current i _v , a positive or a negative torque are generated about a horizontal axis in the drawing and an axial force. As in 4 the three winding pairs ( 6a . 6b ) 6d . 6e ) 6c . 6f ) are also interconnected to the star, whereby the control using a DC link converter is possible. For the design of the control of the thrust bearing 3 the condition must i _u + i _v + i _w = 0 considered.

At the camps in 5 . 6 and 7 are active magnetic radial bearings (For example, the in 5 to 7 shown radial bearing alternative to the in 1 illustrated radial bearings 1 . 2 be used.), in which, as will be described below, by selectively controlling the bearing windings is also possible to impress in addition to the bearing force and torques about an imaginary radial axis.

In 5 are shown a longitudinal and a cross section of a so-called unipolar bearing. Unipolar bearings are hybrid bearings that use a combination of permanent magnets and electromagnets. A unipolar bearing consists of two radial bearing halves 10 and 11 that has a rotor 4 enclose. Each radial bearing half 10 . 11 corresponds to the cross-section shown on the left. Starting from a bearing ring 9 four bearing legs protrude into the bearing interior. To the bearing legs are bearing windings 8th appropriate. The state of the art is that to one direction, in 5 each horizontal or vertical, belonging bearing windings 8th to connect in series. This happens so that by permanent magnets 12 generated magnetic flux (on the right in 5 drawn through) by the electromagnetic bearing halves 10 . 11 each on one side strengthened in terms of amount and weakened in terms of amount on the opposite side, leaving one on the rotor 4 acting force arises. Now be the respective bearing winding pairs of the two radial bearing halves 10 . 11 controlled separately, one is able to control the bearing forces in both radial bearing halves 10 . 11 independently of each other. As a result, in addition to the bearing force, torques can be generated by radial imaginary axes which can be adjusted with respect to their orientation.

The 6 shows a three-phase version of the unipolar bearing. Starting from a bearing ring 9 Three bearing legs protrude into the bearing interior. The principle of operation of the three-phase unipolar bearing design is basically the same as that of the radial bearing in 5 , The three-phase winding design makes the star connection of the bearing windings 8th possible. By separately controlling the two radial bearing halves 10 . 11 can be generated independently forces, which in addition to the bearing forces and rotation moments arise with regard to their orientation adjustable imaginary radial axes. A ring of permanent magnet material is with 12 designated.

Unlike the in 5 and 6 shown hybrid magnetic radial bearings is in 7 a purely electromagnetic homopolar bearing shown. The radial bearing again consists of two radial bearing halves 10 and 11 , at least by magnetically conductive webs 10a are connected and the rotor 4 surround. Each radial bearing half 10 . 11 consists of a bearing ring 9 , of which three bearing legs protrude into the bearing interior. Around each bearing leg is a bearing winding 8th appropriate. The prior art is those two bearing windings, with respect to the two bearing halves 10 . 11 to stand in line. Thus, an electromagnet is formed in the axial direction of the rotor 4 is extensive. Due to the three-phase design of the bearing windings, it is possible to connect the bearing windings to the star. In this case, the radial bearing can be controlled by means of a DC link converter. By separately controlling the two radial bearing halves 10 . 11 , Which are arranged in an advantageous embodiment against each other twisted, different forces, and thus in addition to the bearing force and torques about adjustable imaginary radial axes can be generated.

By 8th is the metrological detection of a bend of a rotor 4 to be illustrated. Under 8a ) is the rotor 4 shown in the unbent state. In comparison, is under 8b ) the curved rotor 4 shown. Since only the basic principle is to be illustrated, only the bending in the drawing plane and also only the sensors for the vertical direction are shown. The distance sensors 14a and 14b are mounted on a spindle housing, not shown, since they are needed for the position control. Will be an additional sensor 13 mounted, for example, the distance to the thrust washer 7 can measure the bending of the rotor 4 getting closed. Based 8th It is clear that despite the same vertical position of the rotor 4 the through the additional sensor 13 measured distance compared between 8a ) and 8b ) varies significantly. From the measured values of the distance sensors 14a and 14b can change the vertical position and inclination of the rotor 4 be calculated. It is particularly advantageous if the position measurements by means of the distance sensors 14a and 14b each in a node of the rotor 4 occur. With the help of the calculated inclination of the rotor 4 can the from the additional sensor 13 supplied distance information about the inclination of the rotor 4 Corresponding amount.

In 9 is again schematically the rotor 4 in bent ( 9b ) and not bent ( 9a ) State shown.

Based 9 illustrates how a bend can be compensated or a bending vibration can be damped. On the rotor 4 the weight force F _g acts. For the storage of the rotor 4 appropriate bearing forces F _{L, 1} and F _{L, 2} must be generated. Around a bend of the rotor 4 to compensate (see 9b )), for example, on the thrust washer 7 additional forces F _k, F _k and _{1, 2} are generated. The amounts of force | F _{k, 1} | and | F _{k, 2} | are the same size and the forces compensate each other, so no axial movement of the rotor 4 arises. However, by the forces F _{k, 1} and F _{k, 2} generates a torque which must be compensated by the bearing forces F ~ _{L, 1} and F ~ _{L, 2} , to the positioning accuracy of the rotor 4 not to worsen.

With the help of the block diagram in 10 The interconnection of the individual function blocks and the blocks themselves should be explained. The block 18 represents the magnetically supported rotor with a suitable bearing or a bearingless motor for generating additional torques. The position of the rotor X _mess is measured for example by means of five position sensors. Alternatively, devices or algorithms for measuring or reconstructing the Lagerwicklungsinduktivitäten be provided, can be closed by the indirect to the position of the rotor. With the help of additional sensors, the position X _{s of} the rotor 4 measured at an additional location. By that in the description too 8th described method is in the bend calculation block 19 reconstructs a measure of the deflection X ~ _s. In the position controller 15 is calculated from the desired position X _soll the rotor and its measured position X _mess the target bearing force F _L. In addition, the output for compensating the bending torque M _{k, should} be weighted corresponding to the target bearing forces F _{L, should be switched} so that F ~ _{L, should} result. To the design of the position controller 15 A variety of methods, such as PID control or Trajektorienfolgeregelung known in the art. In the block 20 are depending on the desired behavior of the torque compensation M _{k, to} calculate the temporal change of the measured deflection and / or the cumulative time measured bending in function of the measured deflection X ~ _s. In this way, a behavior can be achieved in such a way that it responds to a bend with any flexibility and / or any damping behavior. By compensation torques M _{k, which should be} given, for example, proportional to the time cumulation of the bending measured value, a permanent Durchbie be prevented at the measuring location. A torque torque converter 16 calculated from the target bearing forces F ~ _{L, soll} and the compensation torques M _{k, should} , possibly in dependence on the measured position X _{mess of} the rotor, the target currents i _soll . The amperage adjusting device 17 represents the current flowing in the coil current i _is to the required value i _soll a. For this purpose, the actually flowing currents can be measured and with the help of a current regulator, for example. A PI or dead-beat controller, possibly in response to the measured position X _mess , suitable control voltages are calculated and output.

Regulatory description the invention

Based of calculation approaches the invention should be closer be set out. For this purpose, the principle of operation is generally presented and subsequently for many different, advantageous magnetic bearing designs the process described for driving the magnetic bearings.

angenommen werden. Dabei hängen die Koeffizienten λ_v und λ_h vom Aufbau, der Windungszahl und den Materialeigenschaften der Radiallager 1, 2 ab. Die Luftspaltlängen der einzelnen Elektromagnete s_v,1, s_v,2, s_v,3 bzw. s_h,1, s_h,2, s_h,3 lassen sich aus der gemessenen Lage des Rotors 4 in den Radiallagern 1, 2 und den Nominalluftspaltlängen berechnen. Durch Überlagerung der Magnetkräfte F_v,1, F_v,2, F_v,3 bzw. F_h,1, F_h,2, F_h,3 und unter Berücksichtigung der Winkelstellungen der einzelnen Elektromag nete α_v,1, α_v,2, α_v,3 bzw. α_h,1, α_h,2, α_h,3 können die resultierenden Lagerkraftkomponenten F_v,h, F_v,v, bzw. F_h,h, F_h,v in horizontaler und vertikaler Richtung berechnet werden: Fv,h = Fv,1cosαv,1 + Fv,2cosαv,2 + Fv,3cosαv,3 Fv,v = Fv,1sinαv,1 + Fv,2sinαv,2 + Fv,3sinαv,3 Fh,h = Fh,1cosαh,1 + Fh,2cosαh,2 + Fh,3cosαh,3 Fh,v = Fh,1sinαh,1 + Fh,2sinαh,2 + Fh,3sinαh,3. An electromagnetically mounted rotor has the in 1 shown construction. This is the rotor 4 through two three-phase electromagnetic radial bearings 1 . 2 and an axial magnetic bearing 3 stored. The choice of bearing arrangement is free, the in 1 shown bearing arrangement is exemplary. The radial bearings 1 and 2 each consist of three horseshoe-shaped electromagnets. By the winding currents i _{v, 1} , i _{v, 2} , i _{v, 3} or i _{h, 1} , i _{h, 2} , i _{h, 3} in the front and in the rear radial bearing 1 . 2 Magnetic forces F _{v, 1} , F _{v, 2} , F _{v, 3} or F _{h, 1} , F _{h, 2} , F _{h, 3} can be generated. The relationship between magnetic force and winding current can be approximated

be accepted. The coefficients λ _v and λ _h depend on the design, the number of windings and the material properties of the radial bearings 1 . 2 from. The air gap lengths of the individual electromagnets s _{v, 1} , s _{v, 2} , s _{v, 3} and s _{h, 1} , s _{h, 2} , s _{h, 3} can be calculated from the measured position of the rotor 4 in the radial warehouses 1 . 2 and calculate the nominal air gap lengths. By superposition of the magnetic forces F _{v, 1} , F _{v, 2} , F _{v, 3} and F _{h, 1} , F _{h, 2} , F _{h, 3} and taking into account the angular positions of the individual Elektromag Neten α _{v, 1} , α _{v , 2} , α _{v, 3} or α _{h, 1} , α _{h, 2} , α _{h, 3} , the resulting bearing force components F _{v, h} , F _{v, v} , and F _{h, h} , F _{h, v} in horizontal and vertical direction are calculated: F v, h = F v, 1 cos v, 1 + F v, 2 cos v, 2 + F v, 3 cos v, 3 F v, v = F v, 1 sin .alpha v, 1 + F v, 2 sin .alpha v, 2 + F v, 3 sin .alpha v, 3 F h, h = F h, 1 cos h, 1 + F h, 2 cos h, 2 + F h, 3 cos h, 3 F h, v = F h, 1 sin .alpha h, 1 + F h, 2 sin .alpha h, 2 + F h, 3 sin .alpha h, 3 ,

For the special case α _{v, 1} = 0 °, α _{v, 2} = 120 ° and α _{v, 3} = 240 °, the equations become simpler

beschrieben werden. Für jedes Wicklungspaar wurde ein Lagerparameter λ_p,1, λ_p,2, λ_p,3 bzw. λ_n,1, λ_n,2, λ_n,3 eingeführt. Aus der Nominalluftspaltlänge s₀ und der gemessenen axialen Position p_x des Rotors 4 wird die jeweilige Luftspaltlänge berechnet. Der Faktor r steht für den radialen Abstand des Angriffspunktes der Magnetkraft von der Lagermitte. Durch jede Axiallagerhälfte des Axiallagers 3 können bei dieser vorteilhaften Verschaltungsvariante eine axiale Kraft und ein Drehmoment um die Vertikale bzw. Horizontale erzeugt werden.Used for the electromagnetic thrust bearing 3 a warehouse after 2 used, the relationship between winding currents i _{p, 1} , i _{p, 2} , i _{p, 3} or i _{n, 1} , i _{n, 2} , i _{n, 3} (depending on the thrust bearing half), bearing force F _x and bearing torque M _h , M _v with pairwise interconnection of the bearing windings 4 (The star connection of the pairs of windings should not be used initially.) When the bearing halves are rotated by 90 ° with respect to each other F x = F p, 1 + F p, 2 + F p, 3 - F n, 1 - F n, 2 - F n, 3 . M v = r (f n, 2 - F n, 3 ), M H = r (f p, 2 - F p, 3 ) With

to be discribed. A bearing parameter λ _{p 1} was ₁ for each pair of _windings, λ _{p, 2,} λ _{p, 3} or λ _n, λ _{n, 2,} λ _n, introduced. ₃ From the nominal air gap length s ₀ and the measured axial position p _{x of} the rotor 4 the respective air gap length is calculated. The factor r stands for the radial distance of the point of application of the magnetic force from the bearing center. Through each thrust bearing half of the thrust bearing 3 In this advantageous Verschaltungsvariante an axial force and torque can be generated about the vertical or horizontal.

With the help of a rigid body model for the rotor 4 can be equations of motion in the form mp .. x = F x mp .. H = F v, h + F h, h mp .. v = F v, v + F h, v Jd .. H = l v F v, v + l H F h, v + M H Jd .. v = l v F v, h + l H F h, h + M v write. Due to the forces F _x , F _{v, h} , F _{h, h} , F _{v, v} , F _{h, v} and torques M _v , M _h becomes the rigid rotor 4 with the mass m and the moment of inertia J in the directions of the coordinates p _x , p _h , p _v , d _h , d _v accelerated. The bearing forces F _{v, h} , F _{v, v} and F _{h, h} , F _{h, v} act at a distance l _v or l _h from the center of mass on the rotor 4 ,

For the regulation of the position of the rotor 4 a follower with the parameters k ₀ and k _{1 is} used, which is derived from the given position of the rotor 4 and whose time derivatives calculate the required accelerations Ẍ _d : x d = -Ẍ should + k 1 (x mess - Ẋ should ) + k 0 (X mess - X should ) + Ẍ sturgeon ,

The vector X _measured = (p _x p _v p _v d _h d _h) is made up of the coordinates used to describe the position of the rotor 4 together (corresponding to the vectors of the target positions X _soll , the target speeds Ẋ _soll and the target accelerations Ẍ _soll ). In addition, a vector of interference accelerations X _sturgeon can be switched on to improve positioning accuracy. The position _vector X _mess , the first time derivative of the position vector Ẋ _{mess of} the rotor 4 and X Störbeschleunigungsvektor _interference may be measured by sensors or reconstructed from other measured values.

If one selects the setpoint values for the torques M _h , M _v , then using the equations of motion for a rigid body from the components of the desired acceleration vector Ẍ _d, the desired bearing forces (combined to form a vector F ~ _{L, soll} ) for F _x , F _{v, h} , F _{v, v} , F _{h, h} , F _{h, v are} calculated.

und

erfolgen, wobei F₀ eine positiv frei wählbare Arbeitspunktkraft ist. Die Soll-Lagerströme für das Axiallager 3 können aus der Vorgabe für die Lagerdrehmomente M_v, M_h und der Axialkraft F sowie der gemessenen Axialposition p_x durch

berechnet werden, wobei F_x,0, F_p,0 und F_n,0 positiv frei wählbare Arbeitspunktkräfte sind.With the aid of the mathematical bearing models (relationship between the air gaps, the coil currents and the resulting bearing forces), it is possible to determine the position of the rotor from the measured variables p _x , p _h , p _v , d _h , d _v 4 (summarized to vector X _mess ) and the previously calculated desired bearing force vector F ~ _{L, should} (consisting of the setpoints for F _x , F _{v, h} , F _{v, v} , F _{h, h} and F _{h, v} ) and the given values (summarized to the vector M _{k, soll} ) for the bearing torque M _h , M _v, the setpoint values i _soll (vector of desired currents) for the bearing currents i _{p, 1} , i _{p, 2} , i _{p, 3} , i _{n , 1} , i _{n, 2} , i _{n, 3} (thrust bearing flows) and i _{v, 1} , i _{v, 2} , i _{v, 3} , i _{h, 1} , i _{h, 2} , i _{h, 3} (radial bearing currents) , (This calculation will be in 10 through the block 16 The calculation of the desired bearing currents can be exemplary for the front radial bearing 1 for the advantageous embodiment with α _{v, 1} = 0 °, α _{v, 2} = 120 ° and α _{v, 3} = 240 °

and

be done, where F _{0 is} a positive arbitrary operating point force. The nominal bearing currents for the thrust bearing 3 can from the specification for the bearing torque M _v , M _h and the axial force F and the measured axial position p by _x

where F _{x, 0} , F _{p, 0} and F _{n, 0 are} freely selectable operating point forces.

For the method for controlling the thrust bearing 3 as a bearing with additional force or torque impression multiple Verschaltungsvarianten are conceivable. In 3 and 4 By way of example, two variants are shown. In both cases star connection or separate control of the bearing windings is possible. For the design of the driving algorithm, the mathematical model to be used has to be adapted according to the winding distribution, the interconnection of the bearing windings and the orientation of the axial bearing halves. The person skilled in the art, for example, the modeling known as a magnetic network. For the star connection, an additional algebraic condition i ₁ + i ₂ + i ₃ = 0 or i _u + i _v + i _w = 0 must be taken into account.

The in 10 Block No. 19 represents the calculation algorithm for the bending of the rotor 4 , In an advantageous embodiment, the distance sensors 14a . 14b mounted in places where there is no deflection by bending the rotor 4 is to be expected. In addition to the rotor 4 mounted sensors 13 For example, the position X _{s of} the thrust washer 7 detected. However, these measured values X _s do not give exclusively the bending of the rotor 4 Again, but also by a desired change in position of the rotor 4 affected. With the help of the known geometric relationships, it is possible for the skilled man, from the measured values of the sensors _measured X 14a . 14b the position of the rotor 4 with which the measured values X _{s can} be corrected to obtain a measure X _s for the bending of the rotor.

Become the readings of the position sensors 14a . 14b through the bend of the rotor 4 If necessary, the sensor measured values can be separated by filtering into individual frequency ranges in order to obtain suitable measured values. Using a modal analysis, the vibration amplitudes at the mounting points of the sensors 14a . 14b estimated and for the calculation of the bending of the rotor 4 be involved.

Magnetically mounted rotors are usually designed so that the expected frequency range of the excitation of the rotor, for example by the rotation, by machining forces on a tool, etc., below critical natural frequencies of the rotor. In such an advantageous embodiment, it is sufficient to determine the bending of the rotor 4 to process the sensor signals X _s using a high-pass filter. The high-pass filter is dimensioned so that the proportions of the measurement signal, that of the intended movement of the rotor 4 and the movement due to acting disturbances are attenuated, so that one obtains the proportion X ~ _s , that of the bending of the rotor 4 equivalent.

durch

berechnet, wobei die Koeffizienten k₀ und k₁ Reglerparameter sind. Die zeitliche Änderung

des Biegungsmesswertes kann durch einen Differenzenquotienten oder mittels geeigneter Filter (z.B. durch Beobachter) aus X ~_s ermittelt werden. Um eine bleibende Regelabweichung bezüglich der Biegung zu unterbinden, kann zusätzlich ein Integralanteil ergänzt werden:

The controller for the bend is in 10 as a block 20 shown. In this case, the compensation torque M _{k, should} , depending on the measured value X ~ _s , which is a measure of the bend, and its temporal change

by

calculated, wherein the coefficients k ₀ and k _{1 are} controller parameters. The temporal change

the deflection measured value _s can be determined by a difference quotient or using suitable filters (for example, by an observer) from X ~. In order to prevent a permanent deviation with respect to the bend, an additional integral part can be added:

werden in den Starrkörpergleichungen die entsprechenden Drehmomente eingesetzt, wodurch die Radiallager 1, 2 zusätzliche Gegenkräfte aufbringen (vgl. 9b)).The calculated so, in addition to the rotor 4 acting compensating torque M _{k, soll} (consisting of the components M _v and M _h ) can be used to avoid unnecessary control deviations in the calculation of the position controller 15 be taken into account (calculation of F ~ _{L, shall} ). For calculating the target bearing forces

the corresponding torques are used in the rigid body equations, whereby the radial bearings 1 . 2 muster additional opposing forces (cf. 9b )).

wobei l₁ den Abstand zwischen den Mitten der beiden Radiallagerhälften bezeichnet. Daraus ergibt sich für die Vorgabe gewünschter Lagerkräfte und gewünschter Kompensationsdrehmomente eine Berechnungsvorschrift für die Magnetkräfte F_v,1, F_h,1, F_v,2, F_h,2 und damit auch für die Wicklungsströme i_v,1, i_h,1, i_v,2, i_h,2:

Instead of the thrust bearing 3 can also use the radial bearings 1 . 2 be used for the generation of compensation forces or compensation torques. Radial bearings are particularly advantageous for this purpose 1 . 2 in homopolar construction, as in 5 to 7 shown. The force-current relationship, exemplary of the in 5 shown unipolar bearing, corresponds to a good approximation F v, 1 = k i, 1 i v, 1 + k p, 1 p f, v , F h, 1 = k 1 i h, 1 + k p, 1 p f, h . F v, 2 = k 2 i v, 2 + k p, 2 p f, v , F h, 2 = k 2 i h, 2 + k p, 2 p f, h with the bearing coefficients k _{i, 1} , k _{i, 2} , k _{p, 1} , k _{p, 2} , the positions of the rotor 4 in the bearing p _{f, v} , p _{f, h} and the bearing currents i _{v, 1} , i _{h, 1} (first half of the bearing), i _{v, 2} , i _{h, 2} (second bearing half). From the generated magnetic forces F _{v, 1} , F _{h, 1} , F _{v, 2} , F _{h, 2} resulting bearing forces and compensation torques

where l ₁ denotes the distance between the centers of the two radial bearing halves. This results in the specification of desired bearing forces and desired compensation torques calculation rule for the magnetic forces F _{v, 1} , F _{h, 1} , F _{v, 2} , F _{h, 2} and thus also for the winding currents i _{v, 1} , i _{h, 1} , i _{v, 2} , i _{h, 2} :

For the damping of bending vibrations and the compensation of bends, the previously presented active magnetic bearings can be combined, ie, for example, that the use of two unipolar bearings as a radial bearing 1 . 2 and a thrust bearing 3 with additional torque impression is possible.

In summary, this means that when using another suitable magnetic bearing (see for example 6 and 7 ) or in the event of a change in the interconnection of the bearing windings, only the algorithm in the block 16 of the 10 must be adjusted.

field of use the invention

Of the rotor according to the invention can, powered by a motor, for example a cutting tool, like a drill, cutter or turning tools, carry and produce highly accurate holes and contours. The regulation the electromagnetic bearing leaves it to programmatically create round or out-of-round contours, where vibrations and bends of the shaft, due to the engagement of the tool on the material to be compensated. Furthermore, these can additional personnel and / or torques used to provide another bearing function for the Rotor take over or to support further bearing devices of the rotor.

1, 2

radial bearings

3

thrust

4

rotor

5

stator

6 8th

bearing winding

7

bearing disk

9

bearing ring

10 11

Radial bearing halves

10a

Stege made of magnetically conductive material

12

permanent magnet

13

additional sensor

14a, 14b

distance sensor

15

Position controller block

16

Torque-current converter

17

Current setting device

18

block for the magnetically mounted rotor

19

Deflection calculation block

20

Bending regulator block

Claims (18)

Method for driving active magnetic bearings, in which the electromagnetic parts are spatially distributed, and by driving the individual bearing windings distributed on a ferromagnetic part (rotor 4 ) acting forces and / or torques generated for the storage of the ferromagnetic part (rotor 4 ), characterized in that by targeted adjustment of the winding currents to in addition to the bearing forces further forces and / or torques for the damping of vibrations and / or for the compensation of bends of the ferromagnetic part (rotor 4 ) can be generated. A method according to claim 1, characterized in that the calculation of the winding currents in the bearing windings of the magnetic bearing ( 1 . 2 . 3 ) as a function of the measured air gap constellation in the magnetic bearings ( 1 . 2 . 3 ) he follows. A method according to claim 1 or 2, characterized in that the damping of vibrations of the ferromagnetic part (rotor 4 ) is effected by forces and / or torques, which in dependence on the time change of the detected bending of the ferromagnetic part (rotor 4 ) be generated. A method according to claim 1 or 2, characterized in that the compensation of bends of the ferromagnetic part (rotor 4 ) is effected by forces and / or torques which are generated as a function of the detected bending amplitude. A method according to claim 4, characterized in that in a bending compensation by an integral component in a controller ( 20 ) as long as the compensation forces and / or compensation torques are increased until no residual deflection of the ferromagnetic part (rotor 4 ) remains. Method according to one of the preceding claims, characterized in that for the vibration damping or bending compensation of the ferromagnetic part (rotor 4 ) additionally generated forces and torques in the position control of the ferromagnetic part (rotor 4 ). Method according to one of the preceding claims, characterized in that the measured values of position sensors ( 14a . 14b ), which are used for the position control of the ferromagnetic part (rotor 4 ) are mounted, for detecting the bending / bending vibration of the ferromagnetic part (rotor 4 ) be shared. Method according to one of the preceding claims, characterized characterized in that the measured values for detecting the bending / vibration obtained by means of devices for measuring the Lagerwicklungsinduktivitäten become. Method according to one of the preceding claims, characterized in that the bearing windings of the magnetic bearings ( 1 . 2 . 3 ) are connected to the star. A method according to claim 9, characterized in that the bearing windings of the magnetic bearing ( 1 . 2 . 3 ) can be controlled with a DC link converter. Magnetic bearing device for mounting a ferromagnetic part (rotor 4 ), with two electromagnetic radial bearings ( 1 . 2 ) and an electromagnetic thrust bearing ( 3 ), characterized in that the thrust bearing ( 3 ) in addition to the axial bearing forces selectively further forces and / or torques for the damping of vibrations and / or against a bending behavior of the ferromagnetic part (rotor 4 ). Magnetic bearing device according to claim 11, characterized in that one or both radial bearings ( 1 . 2 ) in addition to the radial bearing forces and depending on in the thrust bearing ( 3 ) applied additional forces compensating forces and / or compensation torques in the ferromagnetic part (rotor 4 ) initiates / initiate. Magnetic bearing device for mounting a ferromagnetic part (rotor 4 ), with two electromagnetic radial bearings ( 1 . 2 ) and an electromagnetic thrust bearing ( 3 ), characterized in that one or both radial bearings ( 1 . 2 ) in addition to the radial bearing forces deliberately further forces and / or torques for the damping of vibrations and / or against a bending behavior of the ferromagnetic part (rotor 4 ). Magnetic bearing device according to claim 11, 12 or 13, characterized in that the thrust bearing ( 3 ) essentially one with the rotor ( 4 ) rigidly connected ferromagnetic bearing disk ( 7 ) and on both sides of the bearing disk ( 7 ) Axial bearing halves fixed to the spindle housing with their stators ( 5 ) is constructed. Magnetic bearing device according to claim 12 or 13, characterized in that one or both Ra diallager ( 1 . 2 ) consists of two spindle housing-fixed radial bearing halves ( 10 . 11 ), each with a magnetic pole forming bearing ring ( 9 ), which is the rotor ( 4 ) and are magnetically short-circuited. Magnetic bearing device according to one of claims 11 to 15, characterized in that the ferromagnetic part (rotor 4 ) is exclusively magnetically stored. Magnetic bearing device according to one of claims 11 to 16, characterized in that the rotor ( 4 ) is driven by a motor and at the end carries a cutting tool or a workpiece to be machined. Magnetic bearing device according to one of Claims 11 to 17, characterized by a control of the electromagnetic bearings ( 1 . 2 . 3 ) according to at least one of claims 1 to 10.