JPH09257036A - Magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue operation without stopping a rotary body during instantaneous interruption of service. SOLUTION: A rotary body 2 is held in a given position by magnetically floating a rotary body 2 by magnetic beatings 3, 4, and 5. The rotary body 2 is driven by an electric motor 6 operated as a generator to generate a regenerating power during the stop of a feed from an external source. Usually, a normal operation mode wherein an electric motor 2 and magnetic bearings 3, 4, and 5 are driven by a power from the external source is effected, and operation of a regenerating operation mode wherein the magnetic bearings 3, 4, and 5 are driven by a regenerating power from an electric motor 2 during the stop of a feed from the external source is effected. When the feed of a power from an external source is stopped during operation of an ordinary operation mode, the ordinary operation mode is switched to the regenerating operation mode once and simultaneously the feed state from the external source is investigated. Only when a feed is returned within a given time starting from the stop of a feed, switch to the ordinary operation mode is effected.

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 used in, for example, a turbo molecular pump, and more specifically, it is rotationally driven by an electric motor that functions as a generator that generates regenerative power when power supply from an external power source is stopped. The present invention relates to a magnetic bearing device that magnetically levitates and holds a rotating body by a magnetic bearing.

[0002]

2. Description of the Related Art As a magnetic bearing device used for, for example, a turbo molecular pump, two sets of radial magnetic bearings for supporting a rotating body in a radial direction in a non-contact manner and a rotating body in an axial direction are provided. A set of non-contact supporting axial magnetic bearings, an electric motor that rotationally drives a rotating body, a magnetic bearing control device that controls the electric motor and the magnetic bearing, and a mechanical support for the rotating body when the supporting by the magnetic bearing is lost. Protective bearing (touch-down bearing)
Those equipped with are known. Each magnetic bearing includes a plurality of electromagnets that magnetically attract the rotating body and hold it at a predetermined position. The electric motor normally drives the rotating body by the electric power from the external power source, and acts as a generator that generates regenerative power when the power supply from the external power source is stopped. The magnetic bearing control device includes electromagnet control means, electric motor drive means, power feed stop detection means, and operation mode switching means. The electromagnet control means controls the electromagnets of the magnetic bearings based on the radial and axial positions of the rotating body detected by the position sensor, and the rotating body is controlled by controlling the electromagnets in this manner. It is magnetically levitated in place. The electric motor drive means normally drives the electric motor with the electric power from the external power supply, and outputs the regenerative power from the electric motor to the electromagnet control means when the power supply from the external power supply is stopped. The power supply stop detection means detects the stop of power supply from the external power supply, and outputs a power supply stop signal to the switching means when the power supply is stopped. The operation mode switching means switches the operation mode of the electromagnet control means and the electric motor drive means between the normal operation mode and the regenerative operation mode based on the power supply stop signal from the power supply stop detection means. The normal operation mode is a mode in which the electromagnet control means and the electric motor drive means are driven by the electric power from the external power source, and the regenerative operation mode is a mode in which the magnetic bearing control means is driven by the regenerated electric power from the electric motor drive means. Normally, that is, while the power supply stop signal is not output, the switching means switches to the normal operation mode, and the operation in this mode is continued. Therefore, the electromagnet control means and the electric motor are driven by the electric power from the external power source to hold the rotating body at a predetermined position and rotate it. When the power supply from the external power supply is stopped due to a power failure or the like, a power supply stop signal is output, and the switching means immediately switches to the regenerative operation mode, and operation in this mode is performed. Therefore, even if the electromagnet control means is driven by the regenerative power from the electric motor drive means and the power supply from the external power supply is stopped, the rotating body is supported by the magnetic bearing in a non-contact manner for a while, and the rotating body is decelerated to some extent. At that point, the support by the magnetic bearing is lost, the rotating body is mechanically supported by the protective bearing, further decelerates, and eventually stops.

By the way, to stop the power supply from the external power source,
There are power outages that continue for a relatively long time and instantaneous power outages in which power supply is momentarily stopped for a very short time, for example, 10 msec or less. In the case of a power failure for a long time, of course, it is necessary to switch to the regenerative operation mode and stop the rotating body as described above. On the other hand, in the case of an instantaneous power failure, the power supply is restored in a short time, so there is no problem in continuing the operation in the normal operation mode as it is, but with the conventional magnetic bearing device, as soon as power supply is stopped as described above. Since the regenerative operation mode is switched to and the state is continued and the rotating body is gradually decelerated, the rotating body stops at each momentary power failure. When the rotating body stops, it needs to be restarted, and even if there is an instantaneous power failure, the rotating body must be restarted each time, which is troublesome. Further, when the rotating body is stopped by performing the operation in the regenerative operation mode, the rotating body is supported by the protective bearing while rotating at a certain speed, so that the protective bearing receives an impact force and wears out. . Therefore, if the rotating body is stopped at every momentary power failure as in the prior art, the life of the protective bearing is shortened.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide a magnetic bearing device that can continue operation without stopping the rotating body in the case of an instantaneous power failure.

[0005]

A magnetic bearing device according to the present invention magnetically levitates a rotor by a magnetic bearing and holds the rotor at a predetermined position, and generates regenerative power when power supply from an external power supply is stopped. The rotating body is driven by an electric motor that acts as a generator, and normally, the electric motor from the external power source is operated in a normal operation mode in which the electric motor and the magnetic bearing are driven, and when the power supply from the external power source is stopped, In the magnetic bearing device configured to perform the operation in the regenerative operation mode for driving the magnetic bearing by the regenerative power from the electric motor, when the power supply from the external power source is stopped during the operation in the normal operation mode, Switching to the above-mentioned regenerative operation mode operation, at the same time checking the power supply state from the external power supply, and the power supply is restored within a predetermined time after the power supply is stopped. Only if it is characterized in that it is adapted to switch the operation of the normal operation mode.

The magnetic bearing device according to the present invention further comprises a magnetic bearing having a plurality of electromagnets for magnetically levitating the rotating body, and electromagnet control means for controlling the electromagnet so as to hold the rotating body at a predetermined position, An electric motor that drives the rotating body by electric power from an external power source and acts as a generator that generates regenerative power when power supply from the external power source is stopped,
Normally, the electric motor is driven by electric power from the external power supply, and electric motor drive means for outputting regenerative electric power from the electric motor when power supply from the external power supply is stopped, and power supply stop detection for detecting stop of power supply from the external power supply. Means and switching means for switching the operation modes of the electromagnet control means and the electric motor drive means based on the detection result of the power supply stop detection means, and usually the electromagnet control means and the electromotive force are supplied from the external power source. In a magnetic bearing device configured to drive the magnetic bearing control means by regenerative electric power from the electric motor drive means when performing operation in a normal operation mode for driving the electric motor drive means and stopping supply of power from the external power source, When the switching means detects that the power supply from the external power supply is stopped by the power supply stop detection means, the switching means temporarily turns on. Switching to the operation in the regenerative operation mode, at the same time checking the detection result of the power supply stop detection means, and switching to the operation in the normal operation mode only when the power supply is restored within a predetermined time after the power supply is stopped. It is characterized by.

In the case of a power failure for a long time, the operation is temporarily switched to the regenerative operation mode when the power supply is stopped, and the power supply is stopped even when a predetermined time has elapsed after the power supply was stopped. The operation is continued and the rotating body is stopped as described above.

In the case of a momentary power failure, the operation is once switched to the regenerative operation mode when the power supply is stopped, but the power supply is restored by the elapse of a predetermined time from the stop of the power supply.
Immediately, the operation is switched to the normal operation mode and the operation is continued.

Therefore, according to the magnetic bearing device of the present invention, in the case of an instantaneous power failure, the operation can be continued without stopping the rotating body. Therefore, it is not necessary to restart the rotating body each time an instantaneous power failure occurs, and the life of the protective bearing is extended.

For example, the power supply stop detection means outputs the power supply stop signal when the power supply from the external power source is stopped, and the switching means outputs the power supply stop signal when the power supply stop signal is output. The one-shot pulse signal having a predetermined time width is output, and the operation is switched to the normal operation mode only when the power supply stop signal is not output while the pulse signal is being output.

For example, the predetermined time is about 1 to 5 mse.
c.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows an example of the main part of the mechanical structure of the magnetic bearing device, and FIG. 2 schematically shows an example of the main part of the electrical structure of the magnetic bearing device.

As shown in FIG. 1, a shaft-shaped rotating body (2) is vertically arranged inside a casing (1). Rotating body
(2) is supported in a non-contact manner by the axial magnetic bearing (3) provided in the casing (1) and the upper and lower radial magnetic bearings (4) and (5), and is rotated at high speed by the built-in high-frequency motor (6). To be When the bearings (3), (4) and (5) are no longer supported on the upper and lower two places of the casing (1), the rotating body (2)
Protective bearings (7) (8) are provided for receiving. The protective bearings (7) and (8) are, for example, angular contact ball bearings.

The axial magnetic bearing (3) is for supporting the rotating body (2) in the axial direction (vertical direction), and the flange portion (2a) at the intermediate portion of the rotating body (2) is attached from both upper and lower sides. It is provided with a pair of annular electromagnets (axial electromagnets) (3a) arranged so as to be sandwiched therebetween. Upper and lower axial electromagnets
(3a) is a rotor that attracts the flange (2a) by magnetic force.
(2) is supported in the axial direction in a non-contact manner. casing
The (1) is provided with an axial position sensor (9) for detecting the position of the rotating body (2) in the axial direction.

The radial magnetic bearings (4) and (5) are for supporting the rotating body (2) in the radial direction (horizontal direction). The upper radial magnetic bearing (4) includes two pairs of electromagnets (radial electromagnets) (4a) arranged so as to sandwich the rotating body (2) from both sides in two radial directions orthogonal to each other. The lower radial magnetic bearing (5) also has two pairs of similar radial electromagnets (5a). Radial electromagnet (4
(a) and (5a) attract the rotor (2) by magnetic force and support it in the radial direction in a non-contact manner. Upper radial electromagnet (4a)
2 pairs of radial position sensors (10) for detecting the positions of the two upper portions of the rotating body (2) in the radial directions orthogonal to each other are provided in the vicinity of. Lower radial electromagnet (5
Also in the vicinity of a), there are provided two pairs of radial position sensors (11) for detecting the positions in the lower part of the rotating body (2) in two radial directions orthogonal to each other.

The electric motor (6) comprises a rotor portion (6a) provided on the rotating body (2) and a stator portion (6b) provided on the casing (1) around the rotor portion (6a). This electric motor (6) is usually an external power source (12) which is, for example, a 200 V AC power source.
It is driven by the electric power from the external power source (see Fig. 2).
It acts as a generator that generates regenerative power when the power supply from 2) is stopped.

As shown in FIG. 2, in the magnetic bearing device, the electric motor (6) is controlled and the position sensors (9), (10) and (11) are controlled.
A magnetic bearing control device (13) is provided for controlling the electromagnets (3a) (4a) (5a) based on the output of the. The control device (13) is a DC power supply device (14), an electromagnet control means (15), an inverter device (16) as a motor drive means, a power supply stop detection means (17),
A relay (changeover switch) (18) and a switching means (19) are provided, and an electromagnet control means (15) and a power supply stop detection means (1
The main part of 7) and the switching means (19) is composed of a microcomputer.

The DC power supply device (14) is for converting the AC power from the external power supply (12) into DC power and supplying it to the electromagnet control means (15). The electromagnet control means (15) controls the electromagnets (3a) (4a) (5a) based on the output of the position sensors (9) (10) (11) so as to hold the rotating body (2) at a predetermined position. To control. The inverter device (16) normally drives the electric motor (6) with electric power from the external power source (12), and outputs regenerative electric power from the electric motor (6) as DC power when the power supply from the external power source is stopped. Is. Power supply stop detection means (1
7) monitors the voltage of the external power supply (12) and outputs a power supply stop signal to the switching means (19) during that time when the voltage becomes lower than a predetermined power supply stop detection voltage value. Relay (18)
Is for switching the electromagnet control means (15) to the external power supply (12) side (DC power supply device (14) side) and the inverter device (16) side, and the common terminal of the relay (18) is the electromagnet control means. (15)
Of the DC power supply device (14), and the other switching terminal is connected to the DC regenerative power output terminal of the inverter device (16). The switching means (19) switches the operation mode of the electromagnet control means (15) and the motor drive means (16) between the normal operation mode and the regenerative operation mode based on the power supply stop signal from the power supply stop detection means (17). Is. The normal operation mode is the external power supply (1
2) is a mode in which the electromagnet control means (15) and the electric motor drive means (16) are driven by electric power, and the regenerative operation mode operates the magnetic bearing control means (15) by the regenerative electric power from the electric motor drive means (16). This is the driving mode. Switching means (19)
Switches the relay (18) to the external power supply (12) side in the normal operation mode, and switches the relay (18) to the inverter device (16) side in the regenerative operation mode.

Normally, that is, while the power feed stop detection means (17) is not outputting the power feed stop signal, the switching means (1
The relay (18) is switched to the external power supply (12) side by 9), and the operation in the normal operation mode is performed. Then, the electromagnet control means (15) and the electric motor (6) are driven by the electric power from the external power source (12), and the rotating body (2) is held at a predetermined position by the magnetic bearings (3), (4) and (5). In addition, it is rotationally driven by the electric motor (6).

When the power supply from the external power source (12) is stopped and the power supply stop signal is output from the power supply stop detection means (17), the switching means (19) once causes the relay (18) to operate as an inverter device ( It is switched to the 16) side and switched to regenerative operation mode operation. At the same time, the switching means (19) outputs a one-shot pulse signal having a predetermined time width (for example, 3 msec). During the output of this pulse signal, the power supply stop signal is constantly checked. Then, when the power supply is restored during the output of the one-shot pulse signal and the power supply stop signal is no longer output, the switching means (19) immediately causes the relay (1
8) is switched to the external power supply (12) side and switched to normal operation mode operation. Further, even when the one-shot pulse signal ends, if the power supply stop signal is output, the operation of the regenerative operation mode is continued as it is, and the electromagnet control means (15) is operated by the DC regenerative power from the inverter device (16). Even if it is driven and the power supply from the external power supply (12) is stopped, the rotor (2) is supported by the magnetic bearings (3), (4) and (5) in a non-contact state for a while, and the rotor (2) is At a certain point, the magnetic bearings (3), (4) and (5) lose their support, and the rotor (2) is mechanically supported by the protective bearings (7) and (8).
It will stop soon.

In the case of a power failure for a long time, since the power supply stop signal is output even when the one-shot pulse signal ends, the operation in the regenerative operation mode is continued as it is, and the rotating body is stopped as described above. To be made.

When the power supply is restored during the output of the one-shot pulse signal and the power supply stop signal is not output due to a power failure for a very short time such as an instantaneous power failure, the normal operation mode is switched to. Driving continues. In this case, the power from the external power supply (12) is not supplied to the electromagnet control means (15) from the time the power supply is stopped until it is restored, but the time width of the one-shot pulse signal should be set short. If there is no problem. It is desirable that the time width of the one-shot pulse signal can be adjusted externally. In this way, in the event of a momentary power failure, the operation is continued without stopping the rotor once, so it is not necessary to restart the rotor each time a momentary power failure occurs, and the life of the protective bearing is extended. become longer.

The configuration of each part of the magnetic bearing device is not limited to that of the above-described embodiment, but can be changed as appropriate. For example,
In the above embodiment, the one-shot pulse signal is output when the power supply stop signal is output, and the power supply stop signal is checked during the output of this pulse signal, but without outputting such a pulse signal, It is also possible to start counting the time when the power supply stop signal is output and then check the power supply stop signal until a predetermined count value is reached.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a main part of a magnetic bearing device showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of an electrical configuration of a magnetic bearing device.

[Explanation of symbols]

 (2) Rotating body (3) Axial magnetic bearing (4) (5) Radial magnetic bearing (3a) Axial electromagnet (4a) (5a) Radial electromagnet (6) Electric motor (12) External power supply (15) Electromagnetic control means (16) ) Inverter device (motor drive means) (17) Power supply stop detection means (18) Relay (changeover switch) (19) Changeover means

Claims (4)

[Claims] 1. A magnetic bearing magnetically levitates a rotating body to hold it at a predetermined position, and the rotating body is driven by an electric motor that functions as a generator that generates regenerative power when power supply from an external power source is stopped. , Operating in the normal operation mode for driving the electric motor and the magnetic bearing by the electric power from the external power source, when the power supply from the external power source is stopped,
In the magnetic bearing device configured to perform the operation in the regenerative operation mode for driving the magnetic bearing by the regenerative power from the electric motor, when the power supply from the external power supply is stopped during the operation in the normal operation mode, Switching to the operation in the regenerative operation mode, at the same time checking the power supply state from the external power source, and switching to the operation in the normal operation mode only when the power supply is restored within a predetermined time after the power supply is stopped. Magnetic bearing device characterized by. 2. A magnetic bearing having a plurality of electromagnets for magnetically levitating the rotating body, electromagnet control means for controlling the electromagnet so as to hold the rotating body at a predetermined position, and the rotation by electric power from an external power source. An electric motor that drives the body and acts as a generator that generates regenerative electric power when the power supply from the external power supply is stopped, and normally drives the electric motor with the electric power from the external power supply, and the electric motor when the power supply from the external power supply is stopped. The motor driving means for outputting the regenerative power from the external power source, the power feeding stop detecting means for detecting the power feeding stop from the external power source, and the operation of the electromagnet control means and the motor driving means based on the detection result of the power feeding stop detecting means. Switching means for switching the mode, and normally drives the electromagnet control means and the electric motor drive means by electric power from the external power source. In the magnetic bearing device configured to drive the magnetic bearing control means by the regenerative power from the electric motor drive means when the operation in the normal operation mode is stopped and the power supply from the external power supply is stopped, the switching means includes: When the stop of power supply from the external power supply is detected by the power supply stop detection means, the operation is temporarily switched to the regenerative operation mode, the detection result of the power supply stop detection means is checked at the same time, and the power supply is restored within a predetermined time after the stop of power supply. The magnetic bearing device is characterized in that the operation is switched to the normal operation mode only when the magnetic bearing device is operating. 3. The power supply stop detection means outputs a power supply stop signal when the power supply from the external power source is stopped, and the switching means outputs the power supply stop signal when the power supply stop signal is output. , Outputting a one-shot pulse signal of a predetermined time width, and switching to the normal operation mode operation only when the power supply stop signal is not output while the pulse signal is being output. The magnetic bearing device according to claim 2, which is characterized in that. 4. The magnetic bearing device according to claim 1, wherein the predetermined time is about 1 to 5 msec.