JP2004308823A - Magnetic bearing driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic bearing driving device capable of reducing the damage of touch-down bearings even when the abnormality occurs in a magnetic bearing, a driving circuit and the like. <P>SOLUTION: A plurality of electromagnets X1A of the magnetic bearing supporting a shaft 1 in a state of being magnetically floated, and a driving circuit 30 for driving and controlling the electromagnets are divided into at least two groups. When the abnormality occurs in the electromagnets, the driving circuit and the like, the operation of the driving circuit of the group is stopped, and the driving circuit of the other group is operated to keep an operating state of the electromagnets, and the shaft 1 is forcibly touched down to the touch-down bearings 8, 9, and then stopped by an abnormality processing means, whereby the number of times of collision of the shaft 1 to the touch-down bearings 8, 9 is reduced, and the damage is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic bearing that supports a shaft by magnetically levitating the shaft by electromagnetic force, and more particularly to a magnetic bearing driving device that drives an electromagnet constituting the magnetic bearing.
[0002]
[Prior art]
For example, in a motor that rotates at high speed or a turbo molecular pump that exhausts gas by a rotor, a magnetic bearing device having a shaft that rotationally drives the rotor has two radial magnetic bearings and one axial magnetic bearing. In this case, a floating shaft is supported so as to be capable of controlling five axes. This type of magnetic bearing device is disclosed in Japanese Patent No. 3215842 (Patent Document 1) or Japanese Patent Application Laid-Open No. 8-189527 (Patent Document 2).
[0003]
FIG. 8 shows a configuration of a magnetic bearing device using an active magnetic bearing as the magnetic bearing. This magnetic bearing device actively controls five axes of five degrees of freedom excluding rotation of the shaft 1.
[0004]
That is, a motor rotor 3 constituting the motor 2 is fixed to a substantially center of the shaft 1, and a motor stator 4 constituting the motor 2 is disposed on an inner surface of the case 5 at a position facing the motor rotor 3. A first radial magnetic bearing 6 and a second radial magnetic bearing 7 are provided on the left and right sides of the shaft 1 with the motor 2 interposed therebetween, and a first touch-down bearing 8 and a second touch-down A bearing 9 is provided. An axial magnetic bearing 10 is arranged between the motor rotor 3 of the shaft 1 and the second radial magnetic bearing 7.
[0005]
In the vicinity of the first radial magnetic bearing 6, a pair of radial displacement sensors 11, which face the shaft 1 and detect displacement in the radial direction, are arranged. Then, based on the amount of radial displacement of the shaft 1 detected by the radial displacement sensor 11, a magnetic force is generated in the first radial magnetic bearing 6 by a drive circuit to be described later so that the shaft 1 is controlled to be near the center. Has become.
[0006]
Similarly, the second radial magnetic bearing 7 faces a pair of radial displacement sensors 12 for detecting the radial displacement of the shaft 1, and applies a magnetic force to the second radial magnetic bearing 7 based on the detection amount of the displacement sensor 12. The shaft 1 is generated so as to be controlled so as to come near the center.
[0007]
On the other hand, the axial magnetic bearing 10 includes an axial disk 10a fixed to the shaft 1, an axial displacement sensor 13 for detecting an axial displacement of the shaft 1 via the axial disk 10a, and an axial disk disposed with the axial disk 10a interposed therebetween. It has electromagnets ZA and ZB. The magnetic force of the axial electromagnets ZA and ZB is controlled based on the axial displacement of the shaft 1 detected by the axial displacement sensor 13 so that the axial disk 10a comes to a predetermined position.
[0008]
The touchdown bearings 8 and 9 are used to hold the shaft 1 so that the shaft 1 and the motor rotor 3 do not directly contact the stator 4 when the shaft 1 is not supported by the radial magnetic bearings 6 and 7 and the axial magnetic bearing 10. Is provided. Further, the touchdown bearings 8 and 9 have a gap and a position between the shaft 1 in consideration of magnetic forces of the radial magnetic bearings 6 and 7 and the axial magnetic bearing 10 and gaps between the shaft 1 and the motor rotor 3 and the stator 4. Is set.
[0009]
Further, functionally, the gaps in the radial direction and the axial direction between the shaft 1 and the inner ring portions of the touchdown bearings 8 and 9 are set smaller than the gaps between the magnetic bearing portion and the motor 2, respectively. It is set in consideration of the conditions when the magnetic bearing 1 is not supported by the magnetic bearing 10 and when the magnetic bearing 10 is supported by the magnetic bearings, or when the rotor balance is lost or the rotational load of the rotor is increased. .
[0010]
Further, when the shaft 1 does not magnetically levitate, the portions in contact with the touch-down bearings 8 and 9 are subjected to a surface hardening treatment such as quenching or hard chrome plating to increase the surface hardness. Thereby, the durability when the shaft 1 is supported is enhanced.
[0011]
The first and second radial magnetic bearings 6 and 7 are each configured by an electromagnet in which a coil is wound around a core having a distal end surface facing the shaft 1, and driven by a drive circuit 20 shown in FIG. 1 together with the axial magnetic bearing 10. Is controlled. That is, the drive circuit 20 includes ten sets of drive circuits 20 a, 20 b, 20 c, 20 d, 20 e, 20 f, 20 g, 20 h for controlling the magnetic force of the first and second radial magnetic bearings 6, 7 and the axial magnetic bearing 10. , 20i, and 20j.
[0012]
The control circuit CPU is configured to detect the radial displacement and the axial displacement from the pair of radial displacement sensors 11 and 12 for detecting the displacement in the radial direction and the axial displacement sensor 13 for detecting the axial displacement of the shaft 1. A command is given to the drive circuit 20 to control the magnetic forces of the first and second radial magnetic bearings 6, 7 and the axial magnetic bearing 10 so that the shaft 1 is at a predetermined position. As shown in FIG. 9, the drive circuit 20 includes drive circuits 20a, 20b, 20c, and 20d for driving the electromagnets X1A, X1B, X2A, and X2B provided on the first radial magnetic bearing 6, and Drive circuits 20e, 20f, 20g, 20h for driving the electromagnets X3A, X3B, X4A, X4B provided on the radial magnetic bearing 7, and drive circuits 20i, 20j for driving the electromagnets Z1A, Z1B of the axial magnetic bearing 10. , Two axes in the X and Y directions of the first and second radial magnetic bearings 6 and 7, and one axis in the Z direction of the axial magnetic bearing 10.
[0013]
Such a magnetic bearing supports the shaft 1 that rotates at a high speed of, for example, 100,000 rpm or more, and the first and second radial magnetic bearings 6 and 7 and the axial magnetic bearing 10 are in a non-energized state or at a low speed. In the rotating state, the shaft 1 is supported by the touchdown bearings 8 and 9.
[0014]
[Patent Document 1]
Japanese Patent No. 3215842 [Patent Document 2]
JP-A-8-189527
[Problems to be solved by the invention]
However, the drive circuits 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, and 20j are composed of 10 sets for driving and controlling the first and second radial magnetic bearings 6 and 7 and the axial magnetic bearing 10. If one of the circuits or one of the ten electromagnets X1A, X1B, X2A, X2B, X3A, X3B, X4A, X4B and Z1A, Z1B has an abnormality for some reason, an abnormality detection sensor , The control circuit CPU stops the operation of the abnormal drive circuit or stops the operation of all drive circuits. When one of the drive circuits in which the abnormality has occurred is stopped, the collision of the touchdown bearings 8 and 9 is repeated because the balance of the magnetic force on the shaft 1 is lost and the shaft 1 is eccentric as shown in FIG. Continue rotating while doing. When the operation of all the drive circuits is stopped, the shaft 1 cannot be magnetically levitated, so that the shaft 1 also rotates while repeatedly colliding with the touchdown bearings 8 and 9.
[0016]
The touch-down bearings 8, 9 can support the shaft 1 during normal non-energization or low-speed rotation. However, as described above, when the shaft 1 repeatedly rotates and rotates, Exceeding the allowable number of times may cause intensive damage and eventually destroy. For this reason, there is a problem that the function of the touchdown bearings 8 and 9 is impaired.
[0017]
Therefore, an object of the present invention is to provide a magnetic bearing drive device capable of reducing damage to a touchdown bearing even when an abnormality occurs in a magnetic bearing or a drive circuit.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, in the magnetic bearing driving device according to claim 1, a plurality of electromagnets of a magnetic bearing that magnetically levitates and supports a shaft, and a driving circuit that drives and controls the electromagnets are divided into at least two groups. When an abnormality occurs, the operation of the drive circuits of the group is stopped, and the drive circuits of the other groups are operated to make the electromagnets in an operative state. Is provided, the number of collisions of the shaft with the touch-down bearing is reduced and damage is reduced, so that the life of the touch-down bearing can be extended.
[0019]
Further, in the magnetic bearing driving device according to the second aspect, the shaft is attracted by the magnetic force when the electromagnet is energized, so that the shaft is forcibly touched down by another group of electromagnets in the activated state, and the number of collisions It is possible to reduce.
[0020]
Further, in the magnetic bearing drive device according to the third aspect, by arranging a plurality of electromagnets belonging to one group adjacent to each other, the shaft is biased by the electromagnets in the activated state, and the touchdown bearing is forcibly touched down. It is made to let.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 4 show a magnetic bearing driving device according to the present invention, FIG. 1 shows a magnetic bearing driving circuit constituting an abnormality processing means, FIG. 2 shows a radial magnetic bearing, and FIG. 3 shows an axial electromagnet. ing.
[0022]
The magnetic bearing drive circuit shown in FIG. 1 is configured to drive a five-axis control type magnetic bearing. The five-axis control type magnetic bearing driven and controlled by the magnetic bearing drive circuit is applied to the two radial magnetic bearings and one axial magnetic bearing shown in FIG. 8 described above. Omitted.
[0023]
The magnetic bearing drive circuit includes a control circuit CPU for controlling the magnetic force of the first and second radial magnetic bearings 6, 7 and the axial magnetic bearing 10, and the first and second radial magnetic bearings 6, 7 and the axial magnetic bearing It has ten sets of drive circuits 30 for driving ten electromagnets. These drive circuits are divided into two groups each of which includes a group A drive circuit 31 and a group B drive circuit 32. That is, the group A drive circuit 31 is composed of five sets of drive circuits 31a, 31b, 31c, 31d and 31e for driving one electromagnet in the first and second radial magnetic bearings 6 and 7. Are connected to coils of electromagnets X1A, Y1A, X2A, Y2A, and Z1A, respectively. The group B drive circuit 32 includes five sets of drive circuits 32a, 32b, 32c, and 32d that drive the other electromagnets X1B, Y1B, X2B, Y2B, and Z1B of the first and second radial magnetic bearings 6,7. , 32e.
[0024]
As shown in FIG. 2, four electromagnets X1A, X1B, Y1A, and Y1B each having a coil wound around a core whose front end face is opposed to the shaft 1 are equiangularly arranged on the first radial magnetic bearing 6. Are located. The electromagnet X1A and the electromagnet X1B face each other around the axis of the shaft 1, and the electromagnet Y1A and the electromagnet Y1B face each other. On the other hand, the second radial magnetic bearing 7 is also not shown, but similarly to the first radial magnetic bearing 6, the four electromagnets X2A, X2B, Y2A, and Y2B are arranged at equal angles, and the shaft of the shaft 1 is rotated. The electromagnet X2A and the electromagnet X2B face each other around the core, and the electromagnet Y2A and the electromagnet Y2B face each other. Each of these electromagnets is configured to magnetically attract the shaft 1 by applying a current to each coil by the drive circuits of the groups A and B. 3, two electromagnets Z1A and Z1B are arranged on the axial magnetic bearing 10 so as to face the axial disk 10a fixed to the shaft 1. As shown in FIG. As described above, each of the electromagnets of the first and second radial magnetic bearings 6 and 7 is also divided into the A group and the B group. In FIG. 2, for convenience, the shaft 1 itself is used as a magnet body and magnetically attracted by each electromagnet. However, in practice, a magnetic body such as a permanent magnet is integrally fixed to the shaft 1. This magnetic material is attracted by each electromagnet, and the same applies to the following description.
[0025]
The group A drive circuit 31 and the group B drive circuit 32 described above are each connected to a control circuit CPU, and the group A drive circuits connected to the group A drive circuit 31 and the group B drive circuit 32 based on the control command of the control circuit CPU. And the electromagnets X1A... Z1A and X2A. The control circuit CPU is configured to detect the radial displacement and the axial displacement from the pair of radial displacement sensors 11 and 12 for detecting the displacement in the radial direction and the axial displacement sensor 13 for detecting the axial displacement of the shaft 1. , A command is given to the group A drive circuit 31 and the group B drive circuit 32 to control the magnetic force of the first and second radial magnetic bearings 6, 7 and the axial magnetic bearing 10 so that the shaft 1 is at a predetermined position. ing.
[0026]
On the other hand, the control circuit CPU includes a control circuit 33 for transmitting a control command to the group A drive circuit 31 and the group B drive circuit 32 as shown in FIG. 4, for example. FIG. 4 exemplifies a drive circuit for driving the electromagnet X1A in the first radial magnetic bearing 6, but the same applies to other electromagnets, so that the description of the individual drive circuits is omitted. .
[0027]
The control circuit 33 includes a position detection circuit 34 to which a signal based on the radial displacement detected by the radial displacement sensor 11 is input, and a proportional operation, an integral operation, a differential operation, and the like based on the position signal of the position detection circuit 34. A PID control circuit 35 that performs arithmetic processing and generates a predetermined control voltage corresponding to the displacement of the shaft 1, a limiter circuit 36, and an operational amplifier 37 are provided. The output terminal of the operational amplifier 37 is connected to the base of the transistor 38 of the drive circuit having the collector connected to the coil of the electromagnet X1A, and the current of the coil of the electromagnet X1A is controlled according to the control voltage from the PID control circuit 35. It has become so. The emitter of the transistor 38 is grounded via a resistor R and is connected to the inverting input terminal of the operational amplifier 37.
[0028]
The control circuit CPU sends a control command to the group A drive circuit 31 and the group B drive circuit 32, as shown in FIG. 1, and detects a rotational position of the rotor to rotate the motor. A sensor, a temperature sensor for detecting a temperature abnormality of a motor, a magnetic bearing or the like, a drive inhibition circuit for inhibiting a drive when various abnormalities such as a low voltage (LV), an overcurrent (OC), and a clock abnormality (WDTOF) occur; Various signals such as current feedback for feeding back the current of the motor and the magnetic bearing are input. The above-mentioned drive prohibition circuit operates the motor based on an abnormality signal generated when at least one of the group A drive circuit 31 and the group B drive circuit 32 or each of the electromagnets X1A... A stop signal is output, and constitutes abnormality processing means.
[0029]
Next, the operation of the above-described magnetic bearing drive circuit will be described. Now, it is assumed that, among the electromagnets of the group A, an electromagnet X1A has an abnormality due to, for example, a temperature rise. This state is detected by the temperature sensor, and the signal is output to the control circuit CPU. At this time, the control circuit CPU issues a command signal to stop the driving of all the driving circuits 31a of the group A driving circuit 31 to stop the operation of the driving circuits 31a. Are operated to generate a command signal to forcibly pull the shaft 1, so that the shaft 1 is brought into a state as shown in FIG.
[0030]
FIG. 5 shows an abnormal state of the first radial magnetic bearing 6. As is apparent from this figure, all the operations of the group A drive circuit 31 are stopped, and the operation of the group B drive circuit 32 causes the shaft 1 to be driven by the two group B drive circuits 32 as shown by arrows. It is magnetically attracted to the electromagnets X1B and Y1B. That is, as described above, since the electromagnets X1A and Y1A belonging to the group A and the electromagnets X1B and Y1B belonging to the group B are arranged at positions deviated from the shaft 1, the shaft 1 Are forcibly attracted to the vicinity of the center of the electromagnets X1B and Y1B belonging to. As a result, the shaft 1 comes into contact with the touch bearing 8 to perform a forced touchdown.
[0031]
When the shaft 1 is forcibly touched down with respect to the touch bearing 8, the shaft 1 rotates while substantially touching the touch bearing 8, so that the position is regulated and the movement is suppressed. Therefore, the number of collisions of the shaft 1 with the touch bearing 8 is greatly reduced. The above-described operation is similarly performed for the second radial magnetic bearing 7, and by operating all of the group B drive circuit 32, the electromagnets X2B and Y2B belonging to the group B are operated, and the shaft 1 is touch-touched. 9 is forcibly touched down.
[0032]
By operating all of the B-group drive circuit 32, only the electromagnet Z1B of the two electromagnets Z1A and Z1B in the axial magnetic bearing 10 is activated. As a result, the axial disk 10a is attracted by the electromagnet Z1B, and the shaft 1 moves downward as shown in FIG.
[0033]
As described above, when the shaft 1 is forcibly touched down on the touch bearings 8 and 9, the control circuit CPU based on the abnormal signal generated from the group A drive circuit 31 or the electromagnets X1A. Performs an abnormal process of stopping the rotation drive of the motor 2, whereby the rotation of the shaft 1 is stopped. As a result, the shaft 1 stops with the touch bearings 8 and 9 forcibly touched down.
[0034]
The above-described example describes the case where an abnormality occurs in the electromagnet X1A among the electromagnets in the group A, but the same applies to the case where an abnormality occurs in another electromagnet in the group A. When an abnormality occurs in at least one of the electromagnets of the group B, the shaft 1 is touched by operating the group A drive circuit 31 and stopping the group B drive circuit 32, contrary to the above-described example. The bearing can be stopped with the bearings 8 and 9 forcibly touched down. Further, when an abnormality such as a circuit temperature abnormality or an overcurrent abnormality occurs in the group A drive circuit 31 or the group B drive circuit 32, the group in which the abnormality has occurred is stopped and the normal group is operated. , The shaft 1 can be forcibly touched down on the touch bearings 8 and 9 and finally stopped in this state.
[0035]
FIG. 7 shows another embodiment of the magnetic bearing drive circuit according to the present invention. That is, an example is shown in which the drive circuit 30 for driving the electromagnets of the first and second radial magnetic bearings 6 and 7 is divided into, for example, three, and a coil is wound around a core having a tip end surface facing the shaft 1 The six electromagnets XnA, XnB, XnC, YnA, YnB, and YnC are arranged at equal angles. Then, the electromagnets XnA and YnA belonging to the group A are adjacent to each other, the electromagnets XnB and YnB belonging to the group B are adjacent to each other, and the electromagnets XnC and YnC belonging to the group C are adjacent to each other. A drive circuit (not shown) is connected to each of the three divided electromagnets of groups A, B, and C, and this drive circuit is also divided into groups A, B, and C.
[0036]
In the above configuration, when an abnormality occurs in the electromagnet XnB belonging to the group B due to an overcurrent, the control circuit CPU stops the driving of all the driving circuits of the group B driving circuit, and drives the group A driving circuit and the group C driving circuit. A command signal is issued to operate the. As a result, the shaft 1 is attracted near the middle between the electromagnets YnA and XnC by the operation of the electromagnets XnA, YnA and XnC, YnC belonging to the groups A and C, and the shaft 1 comes into contact with the touch bearing 8. A forced touchdown is performed. After that, similarly to the above-described embodiment, the control circuit CPU performs an abnormal process of stopping the rotation of the motor 2 to stop the rotation of the shaft 1, and the shaft 1 is forcibly touched down to the touch bearings 8 and 9. Stop at The operation described above is common to the first and second radial magnetic bearings 6 and 7, and the description thereof is omitted.
[0037]
The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and can be variously modified without departing from the gist of the present invention. For example, in the magnetic bearing device shown in FIG. 8 to which the present invention is applied, the arrangement and configuration of the radial magnetic bearing and the axial magnetic bearing can be changed in another way. In the above-described embodiment, the five-axis control type magnetic bearing device has been described. However, for example, similarly, only two axes are controlled in the radial direction. The present invention is also applicable to a one-axis to three-axis control type magnetic bearing device.
[0038]
【The invention's effect】
As described above, the magnetic bearing drive device according to claim 1 of the present invention divides a plurality of electromagnets that support the shaft by magnetically levitating and supports the drive circuits for driving and controlling the electromagnets into at least two groups. Since the operation of the drive circuit of the group in which the occurrence has occurred is stopped and the drive circuit of the other group is activated to bring the electromagnet into the operating state, the shaft can be forcibly touched down by the touchdown bearing, and thereafter, the abnormality processing means By stopping the shaft in a state where the shaft is forcibly touched down, the number of times that the shaft collides with the touchdown bearing can be reduced, and the life of the touchdown bearing can be extended by reducing damage to the touchdown bearing.
[0039]
Further, the magnetic bearing driving device according to claim 2 of the present invention causes the shaft to be attracted by the magnetic force when the electromagnet is energized, so that the other group of electromagnets in which the shaft has been activated is forcibly applied by magnetic attraction. Since the touchdown can be performed, the number of times of touchdown bearing collision can be reduced.
[0040]
Further, in the magnetic bearing driving device according to claim 2 of the present invention, a plurality of electromagnets belonging to one group are arranged adjacent to each other. Can be touched down.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a magnetic bearing drive device of the present invention.
FIG. 2 is a configuration diagram showing an arrangement of electromagnets of a radial magnetic bearing in the magnetic bearing drive device of the present invention.
FIG. 3 is a configuration diagram showing an axial magnetic bearing in the magnetic bearing drive device of the present invention.
FIG. 4 is a circuit block diagram showing a drive circuit in the magnetic bearing drive device of the present invention.
FIG. 5 is an explanatory diagram showing an operation state of the radial magnetic bearing in the magnetic bearing drive device of the present invention when an abnormality occurs.
FIG. 6 is an explanatory diagram showing an operation state of the axial magnetic bearing in the magnetic bearing drive device of the present invention when an abnormality occurs.
FIG. 7 is a configuration diagram showing another embodiment of the radial magnetic bearing in the magnetic bearing drive device of the present invention.
FIG. 8 is a sectional view showing a configuration of a magnetic bearing driving device.
FIG. 9 is a block diagram showing a drive circuit of a conventional magnetic bearing drive device.
FIG. 10 is an explanatory diagram showing an operation state of a radial magnetic bearing in a conventional magnetic bearing driving device when an abnormality occurs.
[Explanation of symbols]
Reference Signs List 1 shaft 6 first radial magnetic bearing 7 second radial magnetic bearing 8 first touch-down bearing 9 second touch-down bearing 10 axial magnetic bearing 11 radial displacement sensor 12 radial displacement sensor 13 axial displacement sensor 30 drive circuit 31 A group driving circuit 32 B group driving circuit X1A, Y1A, X2A, Y2A, Z1A Electromagnets X1B, Y1B, X2B, Y2B, Z1B of group A Electromagnet CPU control circuit of group B

Claims (3)

A magnetic bearing drive device that drives and controls an electromagnet of a magnetic bearing that supports the shaft by magnetically levitating,
A plurality of electromagnets and a touch bearing that supports the shaft are arranged around the shaft,
The plurality of electromagnets are divided into at least two groups and arranged separately around the shaft, and a plurality of driving circuits for driving the plurality of electromagnets are divided into at least two groups,
When the electromagnet or the driving circuit is abnormal, the operation of the driving circuit of the group is stopped to activate the driving circuit of another group, and the shaft is driven by the electromagnet driven by the activated driving circuit. A magnetic bearing drive device comprising: an abnormality processing unit that stops the operation of a drive unit that drives the shaft to rotate while making contact with the touch-down bearing. The magnetic bearing drive device according to claim 1, wherein the electromagnet causes the shaft to be attracted by a magnetic force when energized. The electromagnets of each group are arranged at equal intervals around the axis of the shaft so as to magnetically levitate and support the shaft in the radial direction, and a plurality of the electromagnets belonging to one group are arranged adjacently. The magnetic bearing drive device according to claim 1.

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