JP2003083330A - Magnetic bearing device - Google Patents

Abstract

(57) [Problem] To provide a magnetic bearing device capable of easily detecting an abnormality of a displacement detecting means in a short time without adding expensive hardware such as an analog circuit. The magnetic bearing device includes a magnetic bearing having electromagnets (27a, 27b) for magnetically levitating and supporting a rotating body (5) in a non-contact manner, and position sensors (29a, 2) for detecting displacement of the rotating body (5).
9b, a displacement detection means, an electromagnet control means 18 for outputting an electromagnet control signal to the electromagnets 27a, 27b based on a displacement detection signal Se from the displacement detection means, and an excitation current to the electromagnets 27a, 27b with the electromagnet control signal as an input. An electromagnet driving means 14 for supplying is provided. The electromagnet control means 18 includes drive frequency change means 34 and 37 for changing the position sensor drive frequency of the displacement detection means, and changes the drive frequency to determine the abnormality of the displacement detection means from the change in the displacement detection signal Se before and after the change. to decide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a magnet of a magnetic bearing based on a displacement detection signal from a displacement detecting means having a position sensor to magnetically levitate and support a rotating body in a non-contact manner. Bearing device

[0002]

2. Description of the Related Art As a magnetic bearing device of this type, a five-axis control type magnetic bearing device having five control shafts (a control shaft in the axial direction and two control shafts in the radial direction at each of two positions in the axial direction) is known. Are known.

The five-axis control type magnetic bearing device is a set of axial magnetic bearings for supporting a rotating body in the axial control axis direction in a non-contact manner, and two radial control axis directions in which the rotating body is orthogonal to each other at two locations in the axial direction. It is equipped with two sets of radial magnetic bearings that are supported in a non-contact manner. The axial magnetic bearing includes a pair of electromagnets arranged to sandwich the rotating body from both sides in the axial control axis direction and magnetically attract the rotating body. Each radial magnetic bearing is provided with a pair of electromagnets arranged so as to sandwich the rotating body from both sides in the control axis direction in each of the two radial control axis directions and magnetically attract the rotating body.

Further, the magnetic bearing device is based on a displacement detection device as displacement detection means for detecting the displacement of the rotating body in the control axis direction for each of the five control shafts, and the displacement detection result by the displacement detection device. And an electromagnet control device as electromagnet control means for controlling the pair of electromagnets of the control shaft.

The displacement detecting device has one axial position sensor facing the position detecting end surface of the rotating body from one side in the axial control axis direction, and the rotating body is opposed to each radial control axis while sandwiching the rotating body from both sides in the control axis direction. It is provided with a pair of radial position sensors and a displacement calculation unit that drives each position sensor and calculates the displacement of each control shaft of the rotating body from the output of each position sensor. Each position sensor is arranged so as to face an object to be detected (target) provided on the rotating body, and detects the size of a gap with the object to be detected.

[0006]

In the displacement detecting device for a magnetic bearing device as described above, a cable is connected between each position sensor and the displacement calculating part and between the displacement calculating part and the electromagnet control device. Abnormalities such as a bad cable connection or a broken wire of the position sensor may occur. Also,
In the sensor circuit that drives the position sensor in the displacement calculation unit, a malfunction such as a gain defect may occur.

When the above-mentioned abnormality occurs in the displacement detecting device, the following operation abnormality occurs when the magnetic bearing device is started.

For example, if the position sensor cable is not properly connected or is broken, the output signal of the position sensor will be zero.
Therefore, although it is actually displaced, it looks as if it is not. Therefore, no control is performed. Further, when the sensor circuit malfunctions, a predetermined gain cannot be obtained, and the sensor sensitivity is lowered, so that the rigidity of the magnetic bearing is lowered, and touchdown may occur during rotation.

Abnormalities due to poor connection or disconnection of the cables can be detected by, for example, confirming the conduction state between the electromagnet control device and the cables. For that purpose, the conduction states of all the cables can be confirmed. An analog circuit is required to do so, and the electromagnet control device becomes expensive.

Further, it is difficult to detect a defective operation of the sensor circuit and a defective gain, and a person investigates whether the gain is abnormal or normal and adjusts it, or makes an automatic tuning to judge by the result. In any case, there is a problem that the time required for the abnormality determination becomes long at the time of starting the magnetic bearing device.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide a magnetic bearing device capable of easily detecting an abnormality in the displacement detecting means in a short time without adding expensive hardware such as an analog circuit.

[0012]

A magnetic bearing device according to the present invention includes a plurality of electromagnets for magnetically levitating and supporting a rotating body in the axial control axis direction and the radial control axis direction in a non-contact manner. Set of magnetic bearings,
Displacement detecting means having a plurality of sets of position sensors for detecting displacements of the rotating body in the axial control axis direction and the radial control axis direction, and an electromagnet control signal for the electromagnet of the magnetic bearing based on the displacement detection signal from the displacement detection means. In a magnetic bearing device having an electromagnet control means for outputting and an electromagnet drive means for supplying an exciting current to the electromagnet by using an electromagnet control signal as an input, the electromagnet control means changes the drive frequency of the position sensor of the displacement detection means. The present invention is characterized in that the changing means is provided, and the drive frequency is changed, and the abnormality of the displacement detecting means is judged from the change of the displacement detecting signal from the displacement detecting means before and after the changing.

The electromagnet control means preferably comprises software programmable digital processing means such as a digital signal processor, MPU (microprocessor) or the like. A digital signal processor is a dedicated hardware that receives a digital signal, outputs a digital signal, is software programmable, and is capable of high-speed arithmetic processing. Hereinafter, this will be abbreviated as DSP.

With this configuration, the change of the drive frequency of the position sensor and the determination of abnormality by the displacement detection signal can be executed by software.

For example, if the difference between the displacement detection signals before and after changing the drive frequency of the position sensor is smaller than a predetermined value, the electromagnet control means determines that the displacement detection means is abnormal.

According to the magnetic bearing device of the present invention, it is possible to easily determine the abnormality of the displacement detecting means in a short time only by examining the displacement detecting signals before and after changing the driving frequency of the position sensor. In addition, such a judgment can be executed by software and is not only easy to deal with, but also it is not necessary to add expensive hardware such as an analog circuit for checking the connection failure or disconnection of the cable. The control means can be constructed at low cost.

For example, the electromagnet control means does not output the electromagnet control signal for a predetermined time after the power is turned on, and during this period,
The drive frequency is changed, and the abnormality of the displacement detection means is judged from the change in the displacement detection signal from the displacement detection means before and after that.

According to this configuration, since the electromagnet control signal is not output after the power is turned on until the abnormality of the displacement detecting means is determined, the operation abnormality of the magnetic bearing device is not generated even if the displacement detecting means is abnormal. It never happens.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a 5-axis control type magnetic bearing device will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a main part of a mechanical portion of a 5-axis control type magnetic bearing device, FIG. 2 is a transverse sectional view of the same, and FIG. 3 is a block diagram showing an example of its electrical configuration. .

The magnetic bearing device comprises a machine body (1) and a controller (2) connected by a cable. This magnetic bearing device is of a vertical type in which a vertical shaft-shaped rotating body (5) rotates inside a vertical cylindrical casing (4). In the following description, the axial (vertical) axis of the rotating body (5) is the Z axis, and two radial (horizontal) axes that are orthogonal to the Z axis and mutually orthogonal are the X axis and the Y axis. .

The machine body (1) includes a set of axial magnetic bearings (6) for supporting the rotating body (5) in the Z-axis direction in a non-contact manner, and a rotating body.
Two sets of upper and lower radial magnetic bearings (7) and (8) that support (5) in two contact points in the axial direction in the X-axis direction and the Y-axis direction in a non-contact manner, and the position in the axial direction of the rotor (5) and Of the position detection unit (9) for detecting the position in the X-axis direction and the position in the Y-axis direction at the location, the built-in electric motor (10) for rotating the rotating body (5) at high speed, and the rotating body (5). When the rotating body (5) cannot be supported by the magnetic bearings (6), (7), (8) by restricting the movable range in the axial direction and the radial direction, the rotating body (5) is machined at the limit position of the movable range. Two pairs of protective bearings (touchdown bearings) (11) (12)
Is provided. The Z axis is a control axis in the axial direction. X in the upper magnetic bearing (7)
The control axis in the axial direction is the upper X axis, and the control axis in the Y axis direction is the upper Y axis.
The control axis in the X-axis direction in the lower magnetic bearing (8) is the lower X-axis, and the control axis in the Y-axis direction is the lower Y-axis.

The controller (2) includes a displacement calculator (13),
Electromagnet drive circuit (14), motor drive circuit (15) and DSP
A board (16) is provided, and the DSP board (16) is provided with a DSP (18), an AD converter (20) and a DA converter (21) as digital processing means capable of software programming.

The position detecting section (9) includes a single axial position sensor (2) for detecting the position of the rotating body (5) in the Z-axis direction.
3) and two sets of upper and lower radial position sensor units (24) and (25) for detecting the positions of the rotating body (5) in the X-axis direction and the Y-axis direction.

The axial magnetic bearing (6) is arranged so as to sandwich the flange portion (5a) formed integrally with the lower portion of the rotating body (5) from both sides in the Z-axis direction, and magnetically attracts the rotating body (5). Do 1
It has a pair of axial electromagnets (26a) (26b). Axial electromagnets are collectively designated by reference numeral (26). The pair of axial electromagnets (26) having the same characteristics are used.

The axial position sensor (23) includes a rotating body (5).
Is arranged so as to face the lower end surface of the rotating body 5 from the lower side in the Z-axis direction, and outputs a distance signal proportional to the size of the gap with the lower end surface of the rotating body (5).

The two sets of radial magnetic bearings (7), (8) are arranged above the axial magnetic bearing (6) at a predetermined interval in the vertical direction, and the motor (10) is arranged between them. Has been done. The upper radial magnetic bearing (7) is a rotating body (5).
The rotating body (5) is arranged so as to sandwich it from both sides in the X-axis direction.
Pair of upper radial electromagnets (27a) (27b) that magnetically attract
And a pair of upper radial electromagnets (27c) (27d) which are arranged so as to sandwich the rotating body (5) from both sides in the Y-axis direction and magnetically attract the rotating body (5). These radial electromagnets are collectively referred to by the numeral (27). Similarly, lower radial electromagnet
(8) also has two pairs of lower radial electromagnets (28a) (28b) (28c) (28
d) is equipped. These radial electromagnets also have the code (28)
Collectively. As for the radial bearings (27) and (28), at least a pair of electromagnets having the same control shaft have the same characteristics. Preferably, all radial electromagnets (27) (2
The same characteristics are used for 8).

The upper radial position sensor unit (24) is
It is located near the upper radial magnetic bearing (7) and
A pair of upper radial position sensors (29a) (29b) arranged to sandwich the rotating body (5) from both sides in the X-axis direction in the vicinity of the electromagnets (27a) (27b) in the axial direction, and in the Y-axis direction. electromagnet
(27c) (27d) near the rotating body from both sides in the Y-axis direction
It has a pair of upper radial position sensors (29c) and (29d) arranged so as to sandwich (5). These radial position sensors are collectively referred to by the reference numeral (29). Similarly, the lower radial position sensor unit (25) is arranged in the vicinity of the lower radial magnetic bearing (8), and two pairs of lower radial position sensors are arranged.
(30a) (30b) (30c) (30d) are provided. These radial position sensors are also collectively referred to by the reference numeral (30). Each radial displacement sensor (29) (30) outputs a signal proportional to the size of the gap with the outer peripheral surface of the rotating body (5).

Electromagnets (26) (27) (28) and position sensor (23)
(29) and (30) are fixed to the casing (4).

The upper protective bearing (11) is formed of a rolling bearing such as a deep groove ball bearing and can receive a radial load. The outer ring (11a) of the bearing (11) is fixed to the casing (4), and the inner ring (11b) is arranged so as to face the outer peripheral surface of the rotating body (5) with an appropriate gap.
The lower protective bearing (12) is formed of a rolling bearing such as a deep groove ball bearing, and is capable of receiving both axial load and radial load. The outer ring (1
2a) is fixed to the casing (4) and the inner ring (12b) is the rotating body (5).
The annular groove (17) formed on the outer peripheral surface of the is faced with appropriate gaps in the axial direction and the radial direction. Then, the axial movable range of the rotating body (5) is restricted by the size of the axial gap between the inner ring (12b) of the lower bearing (12) and the rotating body (4), and each bearing (11 ) (12) inner ring (11b) (12b) and the rotating body (5) by the size of the radial gap between the rotating body
The movable range in the radial direction of (5) is restricted. And
Protective bearing (11) at the extreme position of rotating body (2)
Even when supported by (12), there is a gap between the rotating body (5) and the electromagnets (26) (27) (28) and the position sensors (23) (29) (30), (5) does not touch the electromagnets (26) (27) (28) and the position sensors (23) (29) (30).

The displacement calculation unit (13) of the controller (2) drives the position sensors (23), (29) and (30) of the position detection unit (9) to drive the position sensors (23), (29) and (30). ), The displacement of the rotating body (5) in the Z-axis direction and the displacements of the upper and lower radial position sensor units (24) (25) in the X-axis direction and the Y-axis direction are calculated. Then, the displacement detection signal as the calculation result is output to the DSP (18) via the AD converter (20). By the position detector (9) and displacement calculator (13),
A displacement detection device is configured as a displacement detection means for detecting the displacement of the rotating body (5) in each control axis direction.

The DSP (18) for each control shaft, based on the digital displacement detection signal representing the displacement of the rotating body (5) input from the AD converter (20), each magnetic bearing (6) (7) ( The electromagnet control signal for each electromagnet (26) (27) (28) in 8) is output to the electromagnet drive circuit (14) via the DA converter (21). Then, the electromagnet drive circuit (14) responds to the exciting current based on the electromagnet control signal from the DSP (18), and the corresponding magnetic bearings (6) (7) (8)
Supply to the electromagnets (26) (27) (28) of the
(5) is supported in a predetermined target floating position in a non-contact manner. DSP
(18), an electromagnet control means for outputting an electromagnet control signal to the electromagnets (26) (27) (28) of each magnetic bearing (6) (7) (8) based on the displacement detection signal from the displacement detection means. The electromagnet control device is configured as follows.

The DSP (18) also outputs a rotation speed command signal to the motor (10) to the motor drive circuit (15). The motor drive circuit (15) includes an inverter and the like, and controls the rotation speed of the motor (10) based on the rotation speed command signal. As a result, the rotating body (5) is replaced by the magnetic bearing (6).
(7) With non-contact support at the target floating position by (8),
It is rotated at high speed by the motor (10).

FIG. 4 shows a machine body (1) and a controller.
Of the configuration of (2), only the part related to control in the upper X-axis direction is shown.

As shown in FIG. 4, the displacement calculator (13) includes
Two sensor circuits (31a) (31b) corresponding to the pair of radial position sensors (29a) (29b), respectively, and an oscillation drive amplifier (32)
And a differential amplifier (33). The DSP (18) is provided with a PID control unit (34), an addition unit (35), a subtraction unit (36), and a drive oscillation unit (37). The DSP (18) is actually operated by a program, but its function is shown as a block in FIG. Control unit (34) and drive oscillator
(37) constitutes drive frequency changing means for changing the position sensor drive frequency. The electromagnet drive circuit (14) is provided with two power amplifiers (38a) (38b) respectively corresponding to the pair of radial electromagnets (27a) (27b).

FIG. 5 shows the output signals of the radial position sensors (29a) (29b) and the signals of the respective parts of the displacement calculating section (13).

The oscillator 37 outputs a drive signal Sa of a predetermined frequency both when checking the presence or absence of abnormality in the displacement detecting device, which will be described later, and during normal magnetic bearing device operation. The drive signal Sa is amplified by the oscillation drive amplifier (32) and supplied to the two sensor circuits (31a) and (31b), and further, the corresponding radial position sensor (29a) from the sensor circuits (31a) and (31b). Supplied to (29b). As a result, from each radial position sensor (29a) (29b), as shown in FIG.
Signals Sb1 and Sb2 having an amplitude corresponding to the size of the gap with the rotating body (5) are output. In each sensor circuit (31a) (31b), the signal Sb1 from each radial position sensor (29a) (29b),
By rectifying Sb2, signals Sc1 and Sc2 as shown in FIG. 5 (b) are obtained, and by further smoothing them, signals Sd1 and Sd2 as shown in FIG. 5 (c) are obtained. . This becomes the distance signals Sd1 and Sd2 which are output signals of the sensor circuits (31a) and (31b) and are sent to the differential amplifier (33). The differential amplifier (33) has two sensor circuits (31a) (31b)
By calculating the difference between the distance signals Sd1 and Sd2 from
As shown in FIG. 5D, a displacement detection signal Se corresponding to the displacement of the rotating body (5) in the upper X-axis direction is obtained. This displacement detection signal Se is sent to the DSP via the AD converter (20).
It is sent to the control unit (34) of (18).

During normal operation of the magnetic bearing device, the oscillator (3
A drive signal Sa having a predetermined operation frequency fo is output from 7). Then, in the control unit (34) of the DSP (18), the displacement calculation unit
Based on the displacement detection signal Se from (13), the control current value for each radial electromagnet (27a) (27b) is calculated. This control current value is added to a constant bias current value (steady current value) in the adding section (35) to calculate the exciting current value for the first radial electromagnet (27a), which is the first
It is output as an electromagnet control signal to the radial electromagnet (27a). This electromagnet control signal is sent to the DA converter (2
Converted to analog value by 1) and electromagnet drive circuit (14)
One of the power amplifiers (38a)
An exciting current is supplied from a) to the first radial electromagnet (27a). On the other hand, the control current value is subtracted from the bias current value in the subtraction section (36) to calculate the exciting current value for the second radial electromagnet (27b), which is the second radial electromagnet (27b ) Is output as an electromagnet control signal. This electromagnet control signal is converted into an analog value by the DA converter (21) and sent to the other power amplifier (38b) of the electromagnet drive circuit (14), and this power amplifier (38b) outputs a second radial electromagnet. Excitation current is supplied to (27b).

In the above magnetic bearing device, when the power is turned on, that is, when the power is turned on, the DSP (18) checks whether or not the displacement detecting device is abnormal. This check is performed by the drive oscillator (3
This is performed by changing the position sensor drive frequency output from 7) and checking the change in the displacement detection signal Se which is the output of the displacement calculation unit (13) before and after that. It should be noted that this check is preferably performed while the electromagnet control signal is not being output from the DSP (18).

The abnormality check of the parts related to the radial position sensors (29) and (30) is performed as follows.

FIG. 5 shows the output signals of the radial position sensors (29a) (29b) and the signals of the respective parts of the displacement calculator (13) when the position sensor drive frequency is changed to two values.

As shown in FIG. 5, when the position sensor drive frequency is changed, the amplitudes of the output signals Sb1 and Sb2 of the radial position sensors (29a) and (b) are changed, whereby the sensor circuits (31a) ( Since the distance signals Sd1 and Sd2 from 31b) change, the displacement detection signal Se which is the output of the differential amplifier (33) also changes.

FIG. 6 shows the distance signals Sd1 and Sd2 from the sensor circuits (31a) and (31b) and the displacement detection signal Se from the differential amplifier (33) when the position sensor drive frequency f is continuously changed. Shows the change. Figure 6 (a) shows the first sensor circuit
6 (b) shows the distance signal Sd1 from the second sensor circuit (31b), and FIG. 6 (c) shows the differential amplifier (3
The displacement detection signals Se from 3) are shown respectively.

When the electromagnet control signal is not output from the DSP (18), the exciting current is not supplied to the electromagnets (27a) (27b), and the rotor (5) is protected by the protective bearings (11) (12). ), And stopped. Therefore, normally, the gap δ between the rotating body (5) and one of the radial position sensors (29a) and (29b) is large, and the gap δ between the other is small. In each drawing of FIG. 6, the solid line indicates each output signal when the gap δ between the rotating body (5) and the first position sensor (29a) is small and the gap δ between the second position sensor (29b) is large. Shows the change.

For example, when the gap δ with the first position sensor (29a) is small and the gap δ with the second position sensor (29b) is large, as shown by the solid line in FIG. Even if the position of the body (5) is constant, if the position sensor drive frequency f changes, the displacement detection signal S from the differential amplifier (33)
e changes in the same way as when the position of the rotating body (5) changes. When the sensor drive frequency f is changed from f1 to f2, the displacement detection signal Se changes from Sx1 to Sx2.

On the other hand, for example, the position sensors (27a) (27
b) If there is an abnormality such as cable breakage on one side, or if there is an abnormality in the gain of the sensor circuits (31a) (31b), the displacement detection signal Se when the sensor drive frequency f is changed Changes less. Further, for example, when both position sensors (27a) and (27b) have abnormality such as disconnection, the displacement detection signal Se does not change at all even if the sensor drive frequency f is changed.

Therefore, by comparing the displacement detection signal Se before and after the sensor drive frequency f is changed with a predetermined threshold value, it is possible to determine whether or not there is an abnormality in the displacement detection device and the type of abnormality.

The same applies when the gap δ with the first position sensor (29a) is large and the gap δ with the second position sensor (29b) is small.

FIG. 7 is a flow chart showing an example of the abnormality determination processing of the displacement detecting device as described above. Next, an example of the processing will be described with reference to this flowchart.

In FIG. 7, when the power is turned on, first, a predetermined initialization process is performed (S1), and the driving signal Sa of the first driving frequency f1 for checking is output from the oscillating unit (37). (S2). Then, the displacement detection signal Se1 from the differential amplifier (33) at that time is detected and stored in the memory (S
3). Next, the drive frequency f of the drive signal Sa from the oscillator (37) is changed to f2 and output (S4), and the displacement detection signal Se2 at that time is detected and stored in the memory (S
Five). Next, the difference ΔSe (= Se1-Se2) between Se1 and Se2 is calculated (S6), and it is checked whether this is within a predetermined allowable range (S7). In S7, if the difference ΔSe is not within the allowable range, it is determined that there is an abnormality, the process proceeds to S8, and the abnormality signal is output. Although not shown in FIG. 7, if Se1 is not within the predetermined specified range in S2, or if Se2 is not within the predetermined specified range in S4, it is determined that there is an abnormality, and the same applies. Is processed. S7
In the case where the difference ΔSe is within the allowable range, it is determined to be normal, the process proceeds to S9, and the drive frequency f of the drive signal Sa from the oscillator (37) is set to the drive frequency fo for operation. (S9), the output of the electromagnet control signal is started (S1
0).

Similarly, the radial position sensor units (24) and (25) are similarly checked for abnormality in the other radial position sensors (29) and (30).

FIG. 8 shows a change in the displacement detection signal from the displacement calculating section (13) regarding the axial position sensor (23) when the position sensor drive frequency f is continuously changed.

For example, the gap δ with the position sensor (23)
8 is small, as shown by the solid line in FIG. 8, even if the position of the rotating body (5) is constant, when the position sensor drive frequency f changes, the displacement detection signal indicates that the position of the rotating body (5) changes. It changes as if you did. When the sensor drive frequency is changed from f1 to f2, the output of the displacement calculator (13) changes from Sz1 to Sz.
Change to z2.

On the other hand, for example, when the position sensor (23) has an abnormality such as a cable disconnection or when the gain of the sensor circuit has an abnormality, the displacement when the sensor drive frequency f is changed. The change in the detection signal becomes small. Further, for example, when the position sensor (23) has an abnormality such as a wire break, the displacement detection signal does not change even if the sensor drive frequency f is changed.

Therefore, by comparing the displacement detection signals before and after the sensor drive frequency f is changed with a predetermined threshold value, it is possible to determine the presence / absence of abnormality of the displacement detection device and the type of abnormality.

The same applies when the gap δ with the position sensor (23) is large.

When the electromagnet control signal is not output from the DSP (18), the exciting current is not supplied to the electromagnets (26a) (26b), and the rotor (5) is protected by the protective bearings (11) (12). ), And stopped. In a horizontal type magnetic bearing device in which a rotating body is arranged horizontally, the gap with the position sensor (23) may be large, small, or somewhere in between. On the other hand, in the vertical type magnetic bearing device in which the rotating body (5) is arranged vertically as described above, normally, the rotating body (5) is stopped at the lower limit position by gravity, so the position sensor The gap with (23) is always small.

The structure of the magnetic bearing device is not limited to that of the above-described embodiment, but can be changed appropriately. For example, in the above embodiment, the inner rotor type magnetic bearing device in which the rotating body rotates inside the casing that is the fixed portion is shown.
The present invention can also be applied to an outer rotor type magnetic bearing device in which a rotating body rotates outside a fixed portion.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a machine body of a magnetic bearing device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the same.

FIG. 3 is a block diagram showing an example of an electrical configuration of the magnetic bearing device.

FIG. 4 is a block diagram showing an example of an electrical configuration of a part relating to a pair of radial electromagnets and a radial position sensor of a machine body and a controller.

FIG. 5 is a time chart showing signals of respective parts of the displacement detection device when the displacement detection device is checked.

FIG. 6 is a graph showing changes in the output of the radial position sensor and the output of the displacement calculator when the drive frequency of the position sensor is changed.

FIG. 7 is a flow chart illustrating a process 1 at the time of checking the displacement detection device.
It is a flowchart which shows an example.

FIG. 8 is a graph showing changes in the output of the axial position sensor when the drive frequency of the position sensor is changed.

[Explanation of symbols]

(5) Rotating body (6) Axial magnetic bearing (7) (8) Radial magnetic bearing (9) Position detector (13) Displacement calculator (14) Electromagnet drive circuit (18) DSP (23) Axial position sensor (26a) (26b) Axial electromagnet (27a) (27b) (27c) (27d) Radial electromagnet (28a) (28b) (28c) (28d) Radial electromagnet (29a) (29b) (29c) (29d) Radial position sensor (30a) (30b) (30c) (30d) Radial position sensor (37) Drive oscillator

Claims (2)

[Claims] 1. A plurality of sets of magnetic bearings having a plurality of electromagnets for magnetically levitating the rotor in the axial control axis direction and the radial control axis direction and supporting it in a non-contact manner, the axial control axial direction of the rotor and the radial control shaft. A displacement detection means having a plurality of sets of position sensors for detecting the displacement in the direction, an electromagnet control means for outputting an electromagnet control signal to the electromagnet of the magnetic bearing based on the displacement detection signal from the displacement detection means, and an electromagnet control signal. In a magnetic bearing device provided with an electromagnet drive means for supplying an exciting current to an electromagnet as an input, the electromagnet control means is provided with drive frequency changing means for changing the position sensor drive frequency of the displacement detecting means, and the drive frequency is changed. Detecting the abnormality of the displacement detection means from the change of the displacement detection signal from the displacement detection means before and after that. Magnetic bearing device characterized by. 2. The electromagnet control means does not output the electromagnet control signal for a predetermined time after the power is turned on, and during this period, the drive frequency is changed so that the displacement detection signal from the displacement detection means before and after the drive frequency is changed. The magnetic bearing device according to claim 1, wherein the magnetic bearing device is for determining an abnormality of the displacement detecting means.