JP2000087967A - Magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic bearing device wherein electric power consumption is lessened by using partial active control, and a controller is easily designed. SOLUTION: A supporting method of a bearing is switched by a bearing supporting method switching part 9 according to a revolution signal of a rotation axis 1 detected by a revolution sensor 7. In the active control, the rotation axis 1 is supported by a radial position controlling electromagnet 3. In the passive control, the rotation axis 1 is supported by a dynamic pressure bearing 5. The switching based on the revolution may be performed according to the threshold value. Or else, it may be performed according to whether the revolution is in the range of the prescribed revolution or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic bearing device, and more particularly, to a magnetic bearing device that partially uses active control to reduce power consumption and facilitate controller design.

[0002]

2. Description of the Related Art Conventionally, active magnetic bearings for supporting a rotating shaft in a non-contact manner by magnetic levitation have been used in various fields. There are various types of active magnetic bearings such as a three-axis control type and a five-axis control type. The three-axis control type active magnetic bearing includes one set of electromagnets for radial position control (x-axis control and y-axis control) that support the rotating shaft, and one set of electromagnets for axial position control (z-axis control). I have.

On the other hand, a five-axis control type active magnetic bearing is composed of two sets of electromagnets (x-axis control and y-axis control) for radial position control that support two different points in the axial direction of the rotating shaft, It consists of one set of electromagnets (z-axis control). The radial position sensor is arranged corresponding to the radial position control electromagnet, and detects the radial position of the rotating shaft. Then, the radial position control electromagnet is controlled such that the radial position detected by the radial position sensor becomes a set value. The same applies to the axial direction.

[0004]

However, the conventional active magnetic bearing always needs to be controlled in order to always support it in a non-contact manner, and it is necessary to continuously supply power to the controller and the magnetic bearing. Further, since the control band is wide, the design of a controller necessary to cover such a wide band may be complicated.

The present invention has been made in view of such conventional problems, and has as its object to provide a magnetic bearing device in which power consumption is reduced by making use of active control partially and controller design is facilitated. Aim.

[0006]

SUMMARY OF THE INVENTION To this end, the present invention provides at least one passive bearing for supporting a rotating shaft and at least one active magnetic for controlling the radial and / or axial position of the rotating shaft. A bearing, a rotational speed detecting means for detecting a rotational speed of the rotary shaft per unit time, a support of the passive type bearing and an active type according to the magnitude and / or range of the rotational speed detected by the rotational speed detecting device. And a switching means for switching between control of the magnetic bearing.

The switching means switches between support by the active magnetic bearing and support by the uncontrolled passive bearing according to the rotational speed of the rotating shaft. The number of rotations of the rotating shaft per unit time is set in advance, and may exceed the set value,
Alternatively, the method of supporting the rotating shaft may be switched when the value becomes less than the set value.

Further, the method of supporting the rotating shaft may be switched between within and outside the range of the predetermined number of rotations. It is desirable that the selection of the set value of the rotation speed and the range of the predetermined rotation speed be determined by design in consideration of the resonance inherent in the rotating shaft, the type of the passive bearing used, and the like, or based on experiments and the like.

Thus, power consumption can be reduced by partially using the active control by the magnetic bearing. Also,
Narrowing the control band facilitates controller design.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a simplified configuration diagram of an embodiment of the present invention. In FIG. 1, the rotating shaft 1 is controlled in radial position while being magnetically levitated in the air by a radial position controlling electromagnet 3 which is an active magnetic bearing. The dynamic pressure bearing 5 which is a passive type bearing is designed to support the rotating shaft 1 and protect it from contact with other components. The passive type bearing may be any type that does not involve active control such as a ball bearing and a dynamic pressure bearing.

The rotation speed sensor 7 detects the rotation speed of the rotating shaft 1 per unit time, and corresponds to a rotation speed detecting means. Then, the rotation speed signal detected by the rotation speed sensor 7 is input to the bearing support system switching unit 9. The bearing support mode switching unit 9 switches the bearing support mode based on the rotation speed signal, and corresponds to a switching unit.

When the control by the active magnetic bearing is selected by the bearing support system switching unit 9, the magnetic bearing control circuit 11
The control of the radial position of the rotary shaft 1 is performed based on a signal from a radial position sensor (not shown). The signal calculated by the magnetic bearing control circuit 11 drives the radial position control electromagnet 3 via the magnetic bearing drive circuit 13.

Next, the operation will be described. Based on the rotational speed signal detected by the rotational speed sensor 7, the bearing support type switching unit 9 switches the bearing support type. The switching method at this time is shown in FIG.
This will be described according to the flowchart of FIG.

Now, consider the time of starting. 2, in step 1 (abbreviated as S1 in the figure; the same applies hereinafter), the number of rotations of the rotating shaft 1 per unit time is detected. Then, in step 2, the rotation speed is compared with a preset value (in this case, the stationary rotation speed (rotation speed = 0)). When it is determined that the rotation speed is equal to or higher than the stationary rotation speed, the process proceeds to step 3 and the control by the active magnetic bearing is started by the radial position control electromagnet 3.
In step 4, position control in the radial direction is performed while the rotating shaft 1 is magnetically levitated.

Thereafter, the flow returns to step 1 to continuously detect the rotational speed. Then, in step 2, the rotational speed detected in step 1 is compared with a preset value (predetermined high-speed rotational speed). When it is determined that the rotation speed is equal to or higher than the predetermined high speed, the process proceeds to step 5 and the control by the active magnetic bearing is stopped.

At the same time, in step 6, the support is switched to the support by the dynamic pressure bearing 5. Thereafter, the flow returns to step 1 to detect the rotation speed again. If it is determined in step 2 that the rotational speed is lower than the predetermined high speed, the process proceeds to step 3 and the control by the active magnetic bearing is started again by the radial position control electromagnet 3.

Contrary to the control described above, when a ball bearing is used as a passive type bearing, the rotating shaft 1 is supported by the ball bearing from a standstill to a low speed rotation.
When the rotation shaft 1 reaches a predetermined high-speed rotation speed, it is desirable to switch to the support by the active control type magnetic bearing. It is also possible to perform active control only when passing through the resonance point, which is a problem unique to the rotating shaft 1, and to perform no control using passive bearings in other rotation speed bands.

FIG. 3 shows an example in which a radial position control electromagnet 3 is disposed at a position corresponding to the antinode of resonance of the rotating shaft 1 in order to avoid such resonance. In this case, one radial position control electromagnet 3 is disposed at a substantially intermediate point between the passive bearings 15A and 15B disposed at two positions in the axial direction. However, the mounting position may be changed depending on the difference in the resonance mode or the type of the passive bearing, or the position in the axial direction may be different.
It may be arranged at a location.

Further, it is also possible that only certain rotation speed bands are not controlled, and active control is performed in other rotation speed bands.
Further, the above-described switching by the bearing support system switching unit 9 may be performed by combining the respective methods. As a result, it is possible to suppress the power consumption caused by performing the active control at all times as in the related art.

Further, since the control band required for the controller is narrowed, the design of the controller is facilitated. The active magnetic bearing may be provided so as to control only the axial position or both the radial position and the axial position.

[0021]

As described above, according to the present invention, the switching means switches between the support of the passive type bearing and the control of the active type magnetic bearing, so that useless power consumption can be suppressed. . Also, since the control band can be narrowed,
Easy controller design

[Brief description of the drawings]

FIG. 1 is a simplified configuration diagram of an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a method of switching bearing support.

FIG. 3 shows an example in which electromagnets for radial position control are arranged at positions corresponding to antinodes of resonance of the rotating shaft.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary shaft 3 Radial position control electromagnet 5 Dynamic pressure bearing 7 Rotation speed sensor 9 Bearing support system switching part 11 Magnetic bearing control circuit 13 Magnetic bearing drive circuit 15A, 15B Passive type bearing

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[Procedure amendment]

[Submission date] November 19, 1999 (1999.11.
19)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

SUMMARY OF THE INVENTION To this end, the present invention provides at least one passive bearing for supporting a rotating shaft and at least one active magnetic for controlling the radial and / or axial position of the rotating shaft. A bearing, rotation speed detecting means for detecting the rotation speed of the rotating shaft per unit time, and a magnitude and / or range of the rotation speed detected by the rotation speed detection device.
Control or Musei of the rotary shaft according to prior Symbol active magnetic bearings Te
Constructed by a switching means switching the control.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

[0021]

As described above, according to the present invention, the switching means increases the rotation speed detected by the rotation speed detecting means.
Rotation by active magnetic bearings depending on size and / or range
Since the control is switched between control and non-control of the axis , wasteful power consumption can be suppressed. Further, since the control band can be narrowed, the controller design becomes easy.

Claims (1)

[Claims] At least one passive bearing for supporting a rotary shaft, at least one active magnetic bearing for controlling a radial position and / or an axial position of the rotary shaft, and a unit time of the rotary shaft per unit time Rotation speed detection means for detecting the rotation speed of the motor, and switching means for switching between support of the passive bearing and control of the active magnetic bearing according to the magnitude and / or range of the rotation speed detected by the rotation speed detection device. A magnetic bearing device comprising: