JP4058724B2 - Magnetic bearing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic bearing device that supports a rotating body in a non-contact manner with a magnetic bearing.
[0002]
[Prior art]
As a magnetic bearing device, a magnetic bearing having an electromagnet that supports a rotating body in a non-contact manner by a magnetic attractive force, a displacement detecting device that detects displacement of the rotating body, and an electromagnet of the magnetic bearing is controlled based on an output of the displacement detecting device. What is provided with the electromagnet control apparatus is known.
[0003]
In controlling the electromagnet of such a magnetic bearing device, it is often important to suppress the natural vibration in the bending mode natural frequency of the rotating body. As a countermeasure, there is a method in which a notch filter that removes a component having the same frequency as the natural frequency of the rotating body from the output of the displacement detection device is provided in the electromagnet control device so that control at the natural frequency is not performed. In any of the methods, control was mainly performed so as not to generate natural vibration.
[0004]
Even if the above-mentioned control is performed, natural vibrations may occur, and if natural vibrations occur during rotation of the rotating body, it is extremely dangerous especially for large rotating bodies such as high-speed rotating bodies and turbo molecular pumps. It is. However, conventionally, no detection means or the like when a natural vibration is generated in a rotating rotating body is provided, and therefore it is impossible to detect the occurrence of the natural vibration of the rotating body.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems and provide a safe magnetic bearing device capable of detecting a natural vibration of a rotating body in an initial stage and performing necessary measures.
[0006]
[Means for Solving the Problems]
The magnetic bearing device according to the present invention includes vibration detection means for detecting only the natural vibration at the primary bending mode natural frequency of the rotating body and outputting a warning signal based on the level of the natural vibration. Are provided with vibration detection circuits for the two radial directions, respectively, and each vibration detection circuit detects the forward natural vibration of the primary bending mode of the rotating body from the output of the displacement detecting means for detecting the displacement of the rotating body in the radial direction. A first band filter provided separately from the electromagnet controller, which passes only the frequency band components centered on the number, and the backward natural frequency of the primary bending mode of the rotating body from the output of the displacement detection means. passing only the component of the frequency band centered, and a second band-pass filter provided separately from the electromagnet control device, our previous Ri natural vibration of the first bending mode of the rotary body It is characterized in that at least one of the micro Atomawari natural oscillation outputs largely a warning signal from the determination level.
[0007]
If the forward natural vibration or the backward natural vibration in the primary bending mode of the rotating body becomes larger than the determination level during the rotation, this is detected by the vibration detection circuit and a warning signal is output. Therefore, the abnormality can be detected at the initial stage where the natural vibration has occurred in the rotating body, and an accident can be prevented beforehand by taking necessary measures such as stopping the rotating body.
[0008]
In addition, occurrence of natural vibration due to aging of the magnetic bearing device can be detected, and the reliability of the magnetic bearing device is improved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
The drawings show an embodiment in which the present invention is applied to a magnetic bearing device in which a vertical rotating body is supported in a non-contact manner by one set of axial magnetic bearings and two sets of upper and lower radial magnetic bearings. In the following description, a control axis in the axial direction (axial direction) is a Z axis, and two radial (radial direction) control axes that are orthogonal to each other and orthogonal to each other are an X axis and a Y axis, respectively. Therefore, in this embodiment, the Z axis is arranged vertically, and the X axis and the Y axis are arranged horizontally.
[0013]
An axial magnetic bearing supports one position in the axial direction of the rotating body in a non-contact manner at a predetermined neutral position in the Z-axis direction. The radial magnetic bearing supports the rotating body in a non-contact manner at predetermined neutral positions in the X-axis direction and the Y-axis direction at two locations in the axial direction of the rotating body.
[0014]
Since the axial magnetic bearing can take a known configuration, illustration and description thereof are omitted.
[0015]
The two sets of radial magnetic bearings have the same configuration, and only the portion of one set of radial magnetic bearings is shown in the drawing.
[0016]
The radial magnetic bearing is a pair of Xs arranged so as to sandwich the rotating body (1) from both sides in the X-axis direction in order to support the rotating body (1) in a non-contact manner in a neutral position in the X-axis direction by magnetic attraction. Axis electromagnet (2) (3), X-axis displacement detector (4) constituting displacement detection means for detecting displacement in the X-axis direction from the neutral position of rotator (1), and rotator (1) X-axis electromagnet controller (5) for supplying an excitation current to each electromagnet (2) (3) based on displacement in the X-axis direction of the rotating body (1) to support the rotating body (1), and the rotating body (1 ) Is supported in a non-contact manner in a neutral position in the Y-axis direction by magnetic attraction force, a pair of Y-axis electromagnets (6), (7) arranged so as to sandwich the rotating body (1) from both sides in the Y-axis direction. And a Y-axis displacement detection device (8) constituting displacement detection means for detecting a displacement in the Y-axis direction from the neutral position of the rotating body (1), and a rotating body for supporting the rotating body at the neutral position Change in the Y-axis direction of (1) And a Y-axis electromagnet controller (9) for supplying an exciting current to each electromagnet (6) (7) based on the position. The electromagnet control devices (5) and (9) are provided in the magnetic bearing control device (10).
[0017]
Each X-axis electromagnet (2) (3) is connected to an X-axis electromagnet controller (5).
[0018]
The X-axis displacement detection device (4) is arranged in the vicinity of the X-axis electromagnets (2) and (3) so as to sandwich the rotating body (1) from both sides in the X-axis direction. A pair of X-axis displacement sensors (11), (12) that detect the size of the gap in the X-axis direction between the two and the output of one displacement sensor (11) from the output of the other displacement sensor (12) A displacement calculation circuit (13) is provided for calculating the displacement of the rotating body (1) from the neutral position in the X-axis direction by subtraction. The output of the arithmetic circuit (13) representing the displacement of the rotating body (1) in the X-axis direction is input to the X-axis electromagnet controller (5).
[0019]
The X-axis electromagnet controller (5) is equipped with a PID control circuit and power amplifier (not shown), and supplies excitation current to each X-axis electromagnet (2) (3) based on the output of the displacement calculation circuit (13). To do. Then, in the pair of electromagnets (2) and (3), a magnetic attraction force is generated by the excitation current, and by controlling the excitation current, the magnetic attraction force is controlled so that the rotating body (1) It is held at a neutral position in the X-axis direction.
[0020]
Each Y-axis electromagnet (6) (7) is connected to a Y-axis electromagnet controller (9).
[0021]
The Y-axis displacement detection device (8) includes a pair of Y-axis displacement sensors (14) and (15) and a displacement calculation circuit (16). The Y-axis displacement sensors (14), (15) and displacement calculation circuit (16) are the same as the X-axis displacement sensors (11), (12) and displacement calculation circuit (13) in the X-axis displacement detector (4). is there.
[0022]
The Y-axis electromagnet control device (9) has the same configuration as the X-axis electromagnet control device (5), and was detected by the Y-axis displacement detection device (8) as in the case of the X-axis electromagnet control device (5). Excitation current is supplied to each Y-axis electromagnet (6) (7) based on the displacement of the rotating body (1) in the Y-axis direction, and the excitation current of each Y-axis electromagnet (6) (7) is controlled. Thus, the rotating body (1) is held at the neutral position in the Y-axis direction.
[0023]
Then, the rotating body (1) is supported in the radial neutral position by the X-axis electromagnets (2) (3) and the Y-axis electromagnets (6) (7), and these two sets of radial magnetic bearings and one set are supported. With this axial magnetic bearing, the rotating body (1) is supported in a non-contact manner at a predetermined neutral position. Although not shown in the figure, the magnetic bearing device is provided with a built-in electric motor, and thereby the rotating body (1) is rotated at a high speed while being supported at the neutral position as described above.
[0024]
In the magnetic bearing control device (10), as described below, only the natural vibration in the X-axis direction at the natural frequency of the rotating body (1) is detected, and a warning signal is generated based on the level of this natural vibration. An X-axis direction vibration detection circuit (first vibration detection circuit) (17) constituting the vibration detection means for outputting is provided.
[0025]
The output of the displacement calculation circuit (13) of the X-axis displacement detector (4) is input to two BPF (band filter) (18) (19), and the output of each BPF (18) (19) is level detected. Input to circuits (20) and (21). The outputs of the level detection circuits (20) and (21) are input to the OR circuit (22), and the output of the OR circuit (22) is output to the outside of the magnetic bearing control device (10) as a warning signal. The center frequency of the first BPF (18) is set to the same frequency as the front natural frequency of the primary bending mode natural frequency at the rated rotational speed or operating rotational speed of the rotating body (1), and the second BPF (19) The center frequency is set to the same frequency as the posterior natural frequency of the primary bending mode natural frequency. That is, the first BPF (18) has a frequency band centered on the front natural frequency as a pass band, and the second BPF (19) has a frequency band centered on the rear natural frequency as a pass band. . The first level detection circuit (20) checks the output level of the first BPF (18), and outputs an off (L level) signal to the OR circuit (22) when it is below a predetermined determination level, which is the determination level. When larger, an on (H level) signal is output to the OR circuit (22). Similarly, the output of the second level detection circuit (21) is turned off when the output level of the second BPF (19) is equal to or lower than a predetermined judgment level, and turned on when it is greater than the judgment level. When the outputs of the two level detection circuits (20) and (21) are both off, the warning signal that is the output of the OR circuit (22) is off. In other cases, that is, the two level detection circuits (20) The warning signal is turned on when at least one of the outputs of (21) is on.
[0026]
Of the output of the X-axis displacement detection device (4), only the frequency band component centering on the front natural frequency of the primary bending mode natural frequency of the rotating body (1) passes through the first BPF (18). . Accordingly, only the forward natural vibration of the rotating body (1) in the X-axis direction is detected by the first BPF (18), and the output of the first level detection circuit (20) is output when the level is higher than the judgment level. Turn on. Of the output of the X-axis displacement detector (4), only the component in the frequency band centered on the back natural frequency of the primary bending mode natural frequency of the rotating body (1) is used as the second BPF (19). pass. Therefore, when the second BPF (19) detects only the backward natural vibration in the X-axis direction of the rotating body (1) and the level is higher than the judgment level, the output of the second level detection circuit (21) is turned on. become. Then, when at least one of the forward natural vibration and the backward natural vibration of the primary bending mode natural frequency of the rotating body (1) exceeds a certain level, the output of the OR circuit (22) is obtained. The warning signal is turned on, and the warning signal is output to the outside from the magnetic bearing control device (10).
[0027]
In the magnetic bearing control device (10), a vibration detecting means for detecting only the natural vibration in the Y-axis direction at the natural frequency of the rotating body (1) and outputting a warning signal based on the level of the natural vibration is configured. A Y-axis direction vibration detection circuit (second vibration detection circuit) (23) is provided. The second vibration detection circuit (23) has the same configuration as that of the first vibration detection circuit (17). From the output of the Y-axis displacement detection device (8), the rated rotation speed or the use rotation speed of the rotating body (1). Only the front natural vibration and the rear natural vibration of the primary bending mode natural frequency in the are detected, and when at least one of them exceeds a certain level, the warning signal is turned on and the external of the magnetic bearing control device (10) Output a warning signal.
[0028]
When a warning signal is output from the first vibration detection circuit (17) or the second vibration detection circuit (23), for example, the driving of the rotating body (1) by the electric motor is stopped.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a cross-sectional portion of a radial magnetic bearing of a magnetic bearing device showing an embodiment of the present invention.
[Explanation of symbols]
(1) Rotating body
(4) (8) Displacement detection device (displacement detection means)
(17) (23) Vibration detection circuit (vibration detection means)
(18) (19) Bandpass filter

Claims (1)

Vibration detection means for detecting only the natural vibration at the primary bending mode natural frequency of the rotating body and outputting a warning signal based on the level of the natural vibration;
The vibration detection means includes vibration detection circuits for each of the two radial directions, and each vibration detection circuit detects the displacement of the rotation body in the radial direction before the primary bending mode of the rotation body. A first band filter provided separately from the electromagnet controller that passes only the frequency band component centered on the natural frequency of rotation, and the post- rotation characteristic of the primary bending mode of the rotating body from the output of the displacement detection means A second band filter provided separately from the electromagnet control device that allows only the frequency band components centered on the frequency to pass , and the front natural vibration and the rear natural vibration of the primary bending mode of the rotating body. A magnetic bearing device that outputs a warning signal when at least one of the levels exceeds a determination level.

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