JP3738337B2 - Magnetic bearing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic bearing device, and more particularly to a magnetic bearing device that supports a rotating body in a non-contact manner in an axial direction (axial direction) and a radial direction (radial direction) with a plurality of sets of magnetic bearings.
[0002]
[Prior art]
As this type of magnetic bearing device, there are a plurality of sets of magnetic bearings having a plurality of electromagnets that non-contact support the rotating body in the axial direction and the radial direction, and a plurality of position sensors that detect the axial and radial positions of the rotating body. Position detection device, electromagnet control device for controlling the electromagnet of each magnetic bearing based on the position detection result by the position detection device, and the limit position of the movable range by regulating the movable range in the axial direction and the radial direction of the rotating body In which a protective bearing made of a rolling bearing that mechanically supports a rotating body is provided.
[0003]
In such a magnetic bearing device, as will be described in detail later, the axial direction and the radial center position (mechanical center position) of the rotating body with respect to the movable range by the protective bearing, and the axial direction with respect to the position of the electromagnet of the magnetic bearing There are a center position in the radial direction (magnetic center position) and an axial position and a center position in the radial direction with respect to the position of the position sensor of the position detector (center position relative to the sensor). The magnetic bearing device is designed such that the mechanical center position, the magnetic center position, and the sensor center position all coincide with each other, but an error may occur between them due to manufacturing errors and assembly errors.
[0004]
In the conventional magnetic bearing device, the electromagnet of the magnetic bearing is controlled so that the rotating body is held at the center position of the sensor, which is the center position of the design, that is, the center of the rotating body coincides with the center position of the sensor. Is done. For this reason, when the counter sensor center position does not coincide with the mechanical center position, the rotating body cannot be held at the mechanical center position. In this case, if the error between the mechanical center position of the rotating body and the center position of the sensor is large, the gap between the rotating body and the protective bearing is partially reduced when the rotating body is held at the center position of the sensor. Various problems occur. In order to avoid such a problem, as described in, for example, Japanese Patent Laid-Open No. 2-107815, the output of the position sensor when the rotating body is moved to the extreme positions of the movable range for each control shaft A magnetic bearing device has been proposed in which a target center position is obtained and a rotating body is magnetically levitated at the mechanical center position.
[0005]
Next, with reference to FIGS. 1 to 5, the above-described method for obtaining the mechanical center position in the magnetic bearing device will be described.
[0006]
1 is a partially cutaway perspective view showing a main part of a magnetic bearing device to which the present invention is applied, FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a transverse sectional view thereof, and FIG. 4 is an example of its electrical configuration. FIG.
[0007]
This magnetic bearing device is of a horizontal type in which a horizontal axis-shaped rotating body (2) rotates inside a horizontal cylindrical casing (1). In the following description, the axial control axis (axial control axis) of the rotating body (2) is the Z axis, and one radial control axis (radial control axis) orthogonal to the Z axis is the X axis, Z axis, and The other radial control axis orthogonal to the X axis is taken as the Y axis. Also, the right side of FIG. 2 is the front, the left side is the rear, and the left and right when viewing the front from the back is the left and right. In this example, the Z-axis direction is the front-rear direction, the X-axis direction is the left-right direction, and the Y-axis direction is the vertical direction, the front side is the Z-axis positive side, the right side is the X-axis positive side, and the upper side is the Y-axis positive side. ing.
[0008]
The magnetic bearing device includes a pair of axial magnetic bearings (3) that support the rotating body (2) in a non-contact manner in the axial direction, and two sets of radial magnetic bearings (4) that support the rotating body (2) in a non-contact manner in the radial direction (4). ) (5), position detection device (6) as position detecting means for detecting the axial and radial positions of the rotating body (2), and a built-in type electric motor for rotating the rotating body (2) at high speed ( 7), an electromagnet control device (8) as an electromagnet control means for controlling the magnetic bearings (3), (4) and (5) based on the position detection result by the position detection device (6), and the rotating body (2) When the rotating body (2) cannot be supported by the magnetic bearings (3), (4) and (5) by restricting the movable range in the axial direction and the radial direction, the rotating body (2) is machined at the extreme position of the movable range. Two sets of front and rear protective bearings (10) and (11) are provided as restricting means for supporting them.
[0009]
The position detection device (6) includes one axial position sensor (12) for detecting the position of the rotating body (2) in the axial direction, and two front and rear positions for detecting the radial position of the rotating body (2). A set of radial position sensor units (13), (14) and a position calculation circuit (15) for calculating the axial position and the radial position of the rotating body (2) from these outputs are provided. The position calculation circuit (15) calculates the position of the center (A) of the rotator (2) with the center position of the sensor to be described later as the origin. The position of the center (A) of the rotator (2) with the center position of the sensor as the origin is simply referred to as the position of the rotator (2).
[0010]
The axial magnetic bearing (3) is a pair of axial electromagnets (16a) (16b) arranged so as to sandwich a flange portion (2a) formed integrally with the front portion of the rotating body (2) from both sides in the Z-axis direction. ). The axial electromagnets are collectively referred to by reference numeral (16), and when it is necessary to distinguish them, the Z-axis positive electromagnet (16a) is called the first axial electromagnet, and the Z-axis negative electromagnet (16b) is called the second axial electromagnet. I will decide.
[0011]
The axial position sensor (12) is disposed so as to face the front end face (position detection end face) of the rotating body (2) from the positive side in the Z-axis direction, and the distance from the front end face of the rotating body (2) (gap) A distance signal proportional to) is output. Then, the arithmetic circuit (15) calculates the axial position from a preset constant value (a value equal to the distance signal of the axial position sensor (12) when the position of the rotating body (2) in the Z-axis direction becomes 0). By subtracting the distance signal of the sensor (21), the position of the rotating body (2) in the Z-axis direction is calculated and output to the electromagnet controller (8).
[0012]
The two sets of radial magnetic bearings (4) and (5) are arranged at a predetermined interval in the front-rear direction on the rear side of the axial magnetic bearing (3), and the motor (7) is arranged between them. It is. The front radial magnetic bearing (4) includes a pair of radial electromagnets (17a) (17b) arranged so as to sandwich the rotating body (2) from both sides in the X-axis direction, and the rotating body (2) in the Y-axis direction. A pair of radial electromagnets (17c) and (17d) are arranged so as to be sandwiched from both sides in the direction. These radial electromagnets are collectively referred to by reference numeral (17), and when it is necessary to distinguish them, the positive electromagnet (17a) in the X-axis direction is the first X-axis electromagnet, and the negative electromagnet (17b) is the second X-axis electromagnet. The positive electromagnet (17c) in the Y-axis direction is referred to as a first Y-axis electromagnet, and the negative electromagnet (17d) is referred to as a second Y-axis electromagnet. Similarly, the rear radial electromagnet (5) also includes a first X-axis electromagnet (18a), a second X-axis electromagnet (18b), a first Y-axis electromagnet (18c), and a second Y-axis electromagnet (18d). These radial electromagnets (18a) to (18d) are also collectively referred to by reference numeral (18).
[0013]
The front radial position sensor unit (13) is arranged in the vicinity of the front radial magnetic bearing (4), and is located near the X-axis electromagnets (17a) and (17b) from both sides in the X-axis direction. ) With a pair of radial position sensors (19a) and (19b) arranged so as to sandwich the rotating body (2) in the vicinity of the Y-axis electromagnets (17c) and (17d) so as to sandwich the rotating body (2) from both sides in the Y-axis direction. And a pair of radial position sensors (19c) and (19d). These radial position sensors are collectively referred to by reference numeral (19), and when it is necessary to distinguish them, the positive side sensor (19a) in the X-axis direction is the first X-axis sensor, and the negative side sensor (19b) is the second X-axis. The positive sensor (19c) in the Y-axis direction is referred to as a first Y-axis sensor, and the negative sensor (19d) is referred to as a second Y-axis sensor. Similarly, the rear radial position sensor unit (14) is also disposed in the vicinity of the rear radial magnetic bearing (5). The first X-axis sensor (20a), the second X-axis sensor (20b), and the first Y An axis sensor (20c) and a second Y-axis sensor (20d) are provided. These radial position sensors (20a) to (20d) are also collectively referred to by reference numeral (20). Each radial position sensor (19) (20) outputs a distance signal proportional to the distance from the outer peripheral surface of the rotating body (2). Then, the position calculation circuit (15) subtracts the distance signal of the first X-axis sensor (19a) from the distance signal of the second X-axis sensor (19b) of the front-side unit (13), so that the front radial magnetic bearing ( 4) Calculate the position of the rotating body (2) in the X-axis direction in the vicinity of 4) and subtract the distance signal of the first Y-axis sensor (19c) from the distance signal of the second Y-axis sensor (19d) of the unit (13) As a result, the position of the rotating body (2) at the same position in the Y-axis direction is calculated and output to the electromagnet controller (8). Similarly, the position calculation circuit (15) calculates the radial magnetic bearing on the rear side based on the difference between the distance signal of the second X-axis sensor (20b) of the rear unit (14) and the distance signal of the first X-axis sensor (20a). Find the position in the X-axis direction of the rotating body (2) in the vicinity of (5) and the difference between the distance signal of the second Y-axis sensor (20d) and the distance signal of the first Y-axis sensor (20c) of the unit (14) Thus, the position of the rotating body (2) at the same position in the Y-axis direction is obtained and output to the electromagnet controller (8).
[0014]
The electromagnets (16), (17), (18) and the position sensors (12), (19), (20) are fixed to the casing (1).
[0015]
The front protective bearing (10) is a rolling bearing such as a deep groove ball bearing, for example, and can receive both an axial load and a radial load. The outer ring (10a) of the bearing (10) is fixed to the casing (1), and the inner ring (10b) is axially and radially aligned with the annular groove (21) formed on the outer peripheral surface of the rotating body (1). It is faced with an appropriate gap. The rear protective bearing (11) is a rolling bearing such as a deep groove ball bearing, for example, and can receive a radial load. The outer ring (11a) of the bearing (11) is fixed to the casing (1), and the inner ring (11b) is arranged to face the outer peripheral surface of the rotating body (1) with an appropriate gap. The axial movable range of the rotating body (1) is restricted by the size of the axial gap between the inner ring (10b) of the front bearing (10) and the rotating body (1), and each bearing ( 10) The movable range in the radial direction of the rotating body (1) is restricted by the size of the radial gap between the inner rings (10b) and (11b) of the (11) and the rotating body (1). Even when the rotating body (2) is supported by the protective bearings (10) and (11) at the extreme position of the movable range, the rotating body (2) and the electromagnets (16) (17) (18) and the position sensor ( There is a gap between (12), (19), and (20), and the rotating body (2) contacts the electromagnets (16), (17), and (18) and the position sensors (12), (19), and (20). There is nothing.
[0016]
Rotating body (2), inner ring (10b) (11b) of protective bearing (10) (11), electromagnet (16) (17) (18) and position sensor (12) (19) (20) The gap is about several millimeters at most, but this is exaggerated in the drawing.
[0017]
The control device (8) determines the position in the Z-axis direction of the rotating body (2) obtained as described above by the position detection device (6), and the rotation in the vicinity of the two sets of radial magnetic bearings (4) and (5). Based on the position of the body (2) in the X-axis direction and the Y-axis direction, the magnitude of the excitation current flowing through the electromagnets (16), (17) and (18) is controlled, whereby the rotating body (2) is described later. It is held at a certain target position.
[0018]
The magnetic bearing device has the above-described mechanical center position, magnetic center position, and sensor center position. The mechanical center position is the position of the center of the movable range regulated by the protective bearings (10) and (11) .In the axial direction, the inner ring (10b) of the front protective bearing (10) is the rotating body (2). At the center of the groove (21) in the axial direction, the axial gap between the end surface of the inner ring (10b) and the side surface of the groove (21) facing this is equal on both sides. The center (A) of the rotating body (2) coincides with the center of the two sets of protective bearings (10) and (11), and the inner ring (10b) of the rotating body (2) and the protective bearings (10) and (11) (11b) is the position where the radial gap is equal over the entire circumference. The magnetic center position is the center position of each pair of electromagnets (16), (17) and (18) facing each control axis direction of each magnetic bearing (3), (4) and (5). The center position of the sensor is the position where the distance between the front end face of the rotating body (2) and the axial position sensor (12) is the predetermined constant value in the axial direction, and the radial direction. Is the center position of each pair of radial position sensors (19) and (20) facing each control axis direction of each radial position sensor unit (13) and (14). The center position of the sensor in the radial direction is O1, and the mechanical center position in the radial direction is O2.
[0019]
In the magnetic bearing device as described above, conventionally, when the operation is started for the first time, the mechanical center position is obtained as follows. Thereafter, the mechanical center position is set as the target position, and the magnetic bearing is used. (3) (4) and (5) are controlled.
[0020]
FIG. 5 shows that the excitation currents of the electromagnets (17) and (18) of the radial magnetic bearings (4) and (5) when the mechanical center position is obtained are shown below, and the rotating body (2) and the protective bearing (11). The positional relationship with the inner peripheral surface of the inner ring (11b) is shown on the upper side. FIG. 5 shows only the relationship between the rotating body (2) and the rear protective bearing (11), but the relationship between the rotating body (2) and the front protective bearing (10) is the same. .
[0021]
Before starting the operation of the magnetic bearing device, the magnetic bearings (3), (4), (5) and the motor (7) are not driven, and the rotating body (2) is the inner ring of the protective bearings (10) (11). (10b) Supported by (11b) and stopped.
[0022]
From such a state, first, mutually equal exciting currents are supplied to the pair of axial electromagnets (16a) and (16b), whereby the rotating body (2) is protected by the protective bearings (10) and (11) in the radial direction. ) In the axial direction and axially supported by the axial magnetic bearing (3) at the center position with respect to the sensor.
[0023]
Next, as shown as T1 in FIG. 5, a constant excitation current I1 is supplied to the second Y-axis electromagnets (17d) and (18d). As a result, the rotating body (2) is attracted to the negative side of the Y axis, contacts the lower limit point Ym of the inner peripheral surface of the protective bearing inner ring (10b) (11b), and is kept at the extreme position on the negative side of the Y axis. Be held. In such a state, the position in the Y-axis direction in each radial position sensor unit (13) (14) of the rotating body (2) is obtained and stored from the output of the position detection device (6). The
[0024]
Next, the supply of excitation current to the second Y-axis electromagnets (17d) and (18d) is stopped, and a constant excitation current I1 is supplied to the second X-axis electromagnets (17b) and (18b) as shown by T2 in FIG. It is done. As a result, the rotating body (2) is attracted to the negative side of the X-axis, contacts the left limit point Xm of the inner peripheral surface of the protective bearing inner ring (10b) (11b), and is held at the extreme position on the negative side of the X-axis. The Then, in such a state, the position in the X-axis direction of each of the radial position sensor units (13) and (14) of the rotating body (2) is obtained and stored.
[0025]
Next, the supply of excitation current to the second X-axis electromagnets (17b) and (18b) is stopped, and a constant excitation current I1 is supplied to the first Y-axis electromagnets (17c) and (18c) as shown as T3 in FIG. It is done. As a result, the rotating body (2) is attracted to the positive side of the Y axis, contacts the upper limit point Yp of the inner peripheral surface of the protective bearing inner rings (10b) and (11b), and is held at the extreme position on the positive side of the Y axis. The Then, in such a state, the position in the Y-axis direction at each radial position sensor unit (13) (14) of the rotating body (2) is obtained and stored.
[0026]
Next, the supply of excitation current to the first Y-axis electromagnets (17c) and (18c) is stopped, and a constant excitation current I1 is supplied to the first X-axis electromagnets (17a) and (18a) as shown as T4 in FIG. It is done. As a result, the rotating body (2) is attracted to the X-axis positive side, contacts the right limit point Xp on the inner peripheral surface of the protective bearing inner ring (10b) (11b), and is held at the extreme position on the X-axis positive side. The Then, in such a state, the position in the X-axis direction of each of the radial position sensor units (13) and (14) of the rotating body (2) is obtained and stored.
[0027]
When the detection of the position of the rotating body (2) at the four extreme positions is completed in this way, the mechanical results in the respective radial position sensor units (13) and (14) are obtained from these detection results as follows. Each center position is determined.
[0028]
First, for the front radial position sensor unit (13), the position of the rotating body (2) in the X-axis positive position at the X4 positive limit position of T4 and the rotating body of the T2 negative position at the X-axis negative position The mechanical center position in the X-axis direction can be obtained by obtaining the midpoint of the position in (2) in the X-axis direction. Similarly, the position in the Y-axis direction of the rotating body (2) at the limit position on the positive Y-axis side of T3 and the position in the Y-axis direction of the rotating body (2) at the limit position on the negative Y-axis side of T1 By obtaining the point, the mechanical center position in the Y-axis direction is obtained. Similarly, the mechanical center positions in the X-axis direction and the Y-axis direction are also obtained for the rear radial position sensor unit (14).
[0029]
However, when the mechanical center position is obtained as described above, there are the following problems.
[0030]
First, an exciting current is suddenly supplied only to one electromagnet (17) and (18) of each radial magnetic bearing (4) and (5), and the rotating body (2) is directed in the direction of the electromagnet (17) and (18). Since the suction is performed, the rotating body (2) collides with the protective bearing inner rings (10b) and (11b), and at this time, a large reaction and vibration may occur, which may damage the protective bearings (10) and (11).
[0031]
In addition, since the excitation current of the electromagnets (17) and (18) is rapidly changed, there is a problem that the inrush current of the power amplifier that drives the electromagnets (17) and (18) is increased, and the life of the power amplifier is shortened.
[0032]
As described above, the magnetic bearing device includes an inner rotor type that rotates inside the casing where the rotating body is a fixed part and an outer rotor type that rotates the rotating body outside the fixed part. This magnetic bearing device has the same problem as described above.
[0033]
In addition, the magnetic bearing device includes a horizontal type in which the rotating body is supported horizontally as described above and a vertical type in which the rotating body is supported vertically. In the case of a vertical magnetic bearing device, However, there is a problem similar to the above.
[0034]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems, prevent a large reaction and vibration to the protective bearing when determining the mechanical center position of the rotating body, prevent the protective bearing from being damaged, and drive the electromagnet An object of the present invention is to provide a magnetic bearing device capable of extending the life of an amplifier.
[0035]
[Means for Solving the Problems and Effects of the Invention]
A magnetic bearing device according to the present invention includes a plurality of sets of magnetic bearings having a plurality of electromagnets that non-contact support the rotating body in the axial direction and the radial direction, and a plurality of position sensors that detect the axial and radial positions of the rotating body. Position detecting means, electromagnet control means for controlling the electromagnet of each magnetic bearing based on the position detection result by the position detecting means, and the movable range in the axial direction and the radial direction of the rotating body. In a magnetic bearing device provided with a protective bearing comprising a rolling bearing that mechanically supports the rotating body at the extreme position of the range, one circumferential position of the circumferential surface of the rotating body in a rotation stopped state faces this Means for sequentially moving the contact point in the circumferential direction of the circumferential surface of the protective bearing by contacting one place in the circumferential direction of the circumferential surface of the protective bearing; Means for detecting the radial position of the center of the rotating body from the detection result of the position by the position detecting means, and the detection result of the radial position of the center of the rotating body at each point of the moving process with respect to the protective bearing. A means for calculating a mechanical center position in the radial direction of the rotating body is provided.
[0036]
In general, the magnetic bearing includes an axial magnetic bearing that supports the rotating body in the axial direction and a radial magnetic bearing that supports the rotating body in the radial direction. For example, detection of the mechanical center position in the radial direction is performed in a state where the rotating body is supported at the axial center position with respect to the sensor by an axial magnetic bearing.
[0037]
The moving range of the rotating body along the peripheral surface of the protective bearing preferably extends over substantially the entire circumference of the protective bearing, but may be a part of the peripheral surface of the protective bearing.
[0038]
When the rotating body is moved in the circumferential direction of the protective bearing while being in contact with the peripheral surface of the protective bearing, the center of the rotating body moves on one circle concentric with the peripheral surface of the protective bearing. In other words, the center of the rotating body moves on a circle centered on the mechanical center position in the radial direction. Therefore, if the center of a circle passing through the center of the rotating body at each point in the moving process of the rotating body is obtained, it becomes the mechanical center position in the radial direction.
[0039]
Since the contact point is sequentially moved in the circumferential direction of the peripheral surface of the protective bearing while the rotary body is always in contact with the peripheral surface of the protective bearing, the rotary body does not collide with the protective bearing. Therefore, there is no large reaction or vibration in the protective bearing, and damage to the protective bearing is prevented.
[0040]
Also, instead of abruptly changing the exciting current of the electromagnet to attract the rotating body to the extreme position as in the past, the rotating body is moved along the peripheral surface of the protective bearing by gradually changing the exciting current of the electromagnet. Therefore, the inrush current of the power amplifier for driving the electromagnet can be reduced, and the life of the power amplifier can be extended.
[0041]
Furthermore, based on the detection result of the center of the rotating body at each point in the moving process of the rotating body, for example, an abnormality of the protective bearing can be detected as follows.
[0042]
Obtain the radius of the circle that passes through the center of the rotating body at each point in the moving process of the rotating body. If this radius is smaller than the specified value, it is determined that the gap between the rotating body and the protective bearing is abnormally small. When the radius is larger than a predetermined value, it is determined that an abnormality such as excessive wear or damage has occurred in the protective bearing. Further, among the detected values of the radial position of the center of the rotating body at each point in the moving process of the rotating body, there seems to be a point where the distance from the mechanical center position in the radial direction is abnormally different from the radius value. In this case, it can be determined that there is an abnormality in the protective bearing.
[0043]
For example, by appropriately controlling the excitation current supplied to each electromagnet of the radial magnetic bearing, the excitation current of each electromagnet is gradually changed so that the peripheral surface of the rotating body is in contact with the peripheral surface of the protective bearing. This contact point is sequentially moved in the circumferential direction of the peripheral surface of the protective bearing.
[0044]
When the radial magnetic bearing includes two pairs of electromagnets facing each other in the control axis direction, for example, the excitation current of each electromagnet is controlled as follows. First, an exciting current is supplied only to the first electromagnet, and the rotating body is attracted to one extreme position in one control axis direction. Next, the exciting current of the first electromagnet is gradually decreased to 0, and the exciting current of the adjacent second electromagnet is gradually increased so that the rotor is controlled along the peripheral surface of the protective bearing. Move to one extreme position in the axial direction. And between this second electromagnet and the next third electromagnet, between this third electromagnet and the next fourth electromagnet, and between this fourth electromagnet and the first first electromagnet. Similarly, the excitation current is controlled. Thereby, it can be made to make 1 round along this peripheral surface in the state which made the rotary body contact the peripheral surface of a protective bearing.
[0045]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments in which the present invention is applied to a horizontal magnetic bearing device as shown in FIGS. 1 to 4 will be described below with reference to the drawings.
[0046]
The mechanical configuration of the magnetic bearing device in this embodiment is the same as that shown in FIGS. The electrical configuration of the magnetic bearing device in this embodiment is substantially the same as that shown in FIG. 4, but the operation of the magnetic bearing control device (8) when obtaining the mechanical center position at the start of operation is the conventional case. Is different.
[0047]
Next, with reference to FIG. 6 and FIG. 7, the operation | movement which calculates | requires a mechanical center at the time of a driving | operation start is demonstrated. FIG. 6 corresponds to FIG. 5 of the conventional example.
[0048]
Also in this case, as in the case of the conventional example, before starting the operation of the magnetic bearing device, the magnetic bearings (3), (4), (5) and the motor (7) are not driven, and the rotating body (2) Are supported by the inner rings (10b) and (11b) of the protective bearings (10) and (11) and stopped. From such a state, first, an equal exciting current is supplied to the pair of axial electromagnets (16a) and (16b), whereby the rotating body (2) is protected by a protective bearing (10 ) In the state of being mechanically supported by (11), it is axially supported by the axial magnetic bearing (3) at the center position of the pair of sensors in the axial direction.
[0049]
Next, as indicated by T1 in FIG. 6, a constant excitation current I1 is supplied to the second Y-axis electromagnets (17d) and (18d). As a result, the rotating body (2) is attracted to the negative side of the Y-axis, contacts the lower limit point Ym of the inner peripheral surface of the protective bearing inner ring (10b) (11b), and is held at the extreme position on the negative side of the Y-axis. Is done. At this time, the rotating body (2) that has stopped in contact with the vicinity of the lower limit point Ym is simply attracted by the electromagnets (17d) and (18d) and brought into contact with the point Ym. ) Hardly moves, and no impact is applied to the protective bearings (10) and (11). Next, the excitation current of the second Y-axis electromagnets (17d) and (18d) is gradually decreased stepwise, and the excitation current of the second X-axis electromagnets (17b) and (18b) adjacent to the clockwise direction is gradually reduced from zero. As shown by T3 in FIG. 6, the excitation current of the second Y-axis electromagnets (17d) and (18d) is set to 0 and the excitation current of the second X-axis electromagnets (17b) and (18b) is increased as shown in FIG. Set to the maximum value I1. In this way, by changing the excitation currents of the second Y-axis electromagnets (17d) (18d) and the second X-axis electromagnets (17b) (18b), as shown at T1, T2 and T3, the protective bearings (10b) (11b) ) The point of contact of the rotating body (2) with the inner peripheral surface of the rotating body gradually moves from the lower limit point Ym to the left limit point Xm in the clockwise direction, and at T3, the rotating body (2) is on the X axis negative side. To the left limit point Xm and held at the limit position on the X axis negative side. Next, the excitation current of the second X-axis electromagnets (17b) and (18b) is gradually decreased stepwise, and the excitation current of the first Y-axis electromagnets (17c) and (18c) adjacent to the clockwise direction is gradually reduced from zero. As shown by T5 in FIG. 6, the excitation current of the second X-axis electromagnets (17b) and (18b) is set to 0 and the excitation current of the first Y-axis electromagnets (17c) and (18c) is set to the maximum value I2. As shown in T3, T4 and T5, the rotating body (2) is brought into contact with the upper limit point Yp in the clockwise direction along the inner peripheral surface of the protective bearing inner rings (10b) (11b). Move to the extreme limit on the positive side. Next, similarly to the above, by changing the exciting current of the first Y-axis electromagnets (17c) (18c) and the first X-axis electromagnets (17a) (18a) adjacent to the first Y-axis electromagnets (17c) (18c), the rotating body (2 ) In the clockwise direction from the limit position on the positive side of the Y axis to the limit position on the positive side of the X axis that contacts the right limit point Xp. Next, similarly to the above, by changing the excitation current of the first X-axis electromagnets (17a) (18a) and the second Y-axis electromagnets (17b) (18b) adjacent to the clockwise direction, the rotating body (2 ) In the clockwise direction from the extreme position on the X-axis positive side to the extreme position on the negative Y-axis side. Thus, the rotating body (2) makes one round in the clockwise direction along the inner peripheral surface of the inner side of the protective bearing inner ring (10b) (11b).
[0050]
The change pattern of the increase and decrease of the excitation current is the same in the first X-axis electromagnets (17a) (18a), the second X-axis electromagnets (17b) (18b), and the second Y-axis electromagnets (17d) (18d). Is the change pattern of the excitation current of the first Y-axis electromagnets (17c) and (18c) plus the amount corresponding to the gravity acting on the rotating body (2) (the hatched portion in FIG. 6). .
[0051]
At a plurality of points in the moving process of the rotating body (2), from the output of the position detection device (6), the radial position sensor units (13), (14) of the rotating body (2) in the X-axis direction and The position in the Y-axis direction is obtained and stored.
[0052]
When the detection of the position of the rotating body (2) at each point in the moving process of the rotating body (2) is completed in this way, the diameter of each radial position sensor unit (13) (14) is determined from these detection results. A mechanical center position in the direction is determined.
[0053]
As described above, when the rotating body (2) is moved in the circumferential direction of the inner peripheral surface while being in contact with one place on the inner peripheral surface of the protective bearing inner ring (10b) (11b), the rotating body (2) The center (A) of is moved on a circle centered on the mechanical center position O2 in the radial direction. Accordingly, if the center of a circle passing through the center (A) of the rotating body (2) at each point in the moving process of the rotating body (2) is obtained, it becomes the radial mechanical center position O2.
[0054]
FIG. 7 shows the detection result of the position of the rotating body (2) in the radial position sensor unit (14) on the rear side in the XY coordinates with the center position O1 as the origin as the origin. From such a detection result, for example, the circle (C) passing through the center (A) of the rotating body (2) and its center are obtained by the method of least squares, and the center of this circle (C) is determined as the rear side. This is the radial mechanical center position O2 in the radial position sensor unit (14). At the same time, the radius Rx in the X-axis direction and the radius Ry in the Y-axis direction of the circle (C) passing through the center (A) of the rotating body (2) are also obtained. The same applies to the front radial position sensor unit (13).
[0055]
After obtaining the mechanical center position in the radial direction as described above, the abnormality of the protective bearings (10) and (11) is detected as follows.
[0056]
For example, when the radii Rx and Ry of the circle (C) passing through the center (A) of the rotating body (2) obtained as described above are smaller than a predetermined value, the rotating body (2) and the protective bearing (10) It is determined that the gap with (11) is abnormally small. On the other hand, when the radii Rx and Ry are larger than the predetermined values, it is determined that abnormalities such as excessive wear and damage have occurred in the protective bearings 10 and 11. Among the detected values of the center (A) of the rotating body (1) at each point of the moving process of the rotating body (2), the distance from the radial mechanical center position O2 is the value of the radius Rx, Ry. Even if there are abnormally different points, it is judged that there is an abnormality in the protective bearing (10) (11).
[0057]
When such an abnormality is detected, an alarm is issued and the magnetic bearing device is not started.
[0058]
When determining the mechanical center position in the radial direction, keep this contact point in a state where the rotating body (2) is always in contact with the inner peripheral surface of the inner ring (10b) (11b) of the protective bearing (10) (11). Since the inner circumferential surfaces of the protective bearing inner rings (10b) and (11b) are sequentially moved in the circumferential direction, the rotating body (2) does not collide with the protective bearing inner rings (10b) and (11b). Therefore, no great reaction or vibration occurs in the protective bearings (10) and (11), and the protective bearings (10) and (11) are prevented from being damaged. In addition, instead of attracting the rotating body (2) to the extreme position by abruptly changing the excitation current of the electromagnets (16), (17), (18) as in the past, the electromagnets (16), (17), (18) In order to drive the electromagnets (16), (17) and (18), the rotating body (2) is moved along the inner peripheral surface of the protective bearing inner rings (10b) and (11b) by gradually changing the excitation current of The inrush current of the power amplifier can be reduced and the life of the power amplifier can be extended.
[0059]
When the mechanical center position in the radial direction is obtained as described above and there is no abnormality, each electromagnet of the radial magnetic bearing (4) (5) is set with the obtained mechanical center position in the radial direction as the target position. (17) The exciting current of (18) is controlled to support the rotating body (2) in the radial direction in a non-contact manner. And in such a state, the mechanical center position of an axial direction is calculated | required like the past. For example, the excitation current of the second axial electromagnet (16b) is set to 0, and the rotating body (2) is attracted to the extreme position on the positive side of the Z-axis by the first axial magnetic bearing (16a). Find the axial position. Next, the exciting current of the first axial electromagnet (16a) is set to 0, and at the same time, a constant exciting current is supplied to the second axial electromagnet (16b), and the rotating body (2) is driven by the second axial magnetic bearing (16b). Is drawn to the extreme position on the negative side of the Z-axis, and the position of the rotating body (2) in the Z-axis direction is obtained. Then, the midpoint of the position in the Z-axis direction of the rotating body (2) at both extreme positions is obtained, and this is set as the mechanical center position in the axial direction.
[0060]
Also in this case, an abnormality of the protective bearing (10) can be detected from the position in the Z-axis direction of the rotating body (2) at both extreme positions. That is, when the difference in the Z-axis position of the rotating body (2) at both extreme positions is smaller than a predetermined value, the axial gap between the rotating body (2) and the protective bearing (10) is abnormally small. On the contrary, when this difference is larger than a predetermined value, it is determined that an abnormality such as excessive wear or damage has occurred in the protective bearing (10).
[0061]
Even when such an abnormality is detected, an alarm is issued and the magnetic bearing device is not started.
[0062]
When the mechanical center position in the axial direction is obtained as described above and there is no abnormality, the obtained mechanical center position in the axial direction is set as the target position, and each electromagnet (12) of the axial magnetic bearing (3) Control the excitation current. Thus, the rotating body (2) is supported in a non-contact manner at the mechanical center position.
[0063]
In the case of the horizontal magnetic bearing device as in this embodiment, gravity acts downward (toward the Y-axis negative side) on the rotating body (2). For this reason, in the process of determining the radial mechanical center position O2, the rotating body (2) is a protective bearing when the rotating body (2) is positioned at the lower (Y-axis negative side) extreme position. (10) The downward force in the Y-axis direction on (11) is larger than the magnetic attraction force of the electromagnets (17d) and (18d) by the amount of gravity, and the rotating body (2) is located at the extreme position on the upper side (Y-axis positive side). In the state of being positioned at, the upward force in the Y-axis direction that the rotating body (2) exerts on the protective bearings (10) and (11) is smaller than the magnetic attractive force of the electromagnets (17c) and (18c) by the amount of gravity. Therefore, if the exciting currents of the electromagnets (17d), (18d), (17c), and (18c) in the above two states are made equal, the rotating body (2) is attached to the protective bearings (10) and (11) at the upper and lower extreme positions. A large difference occurs in the force in the Y-axis direction, resulting in a difference in the amount of deformation in the radial direction of the protective bearings (10) and (11). For this reason, an error occurs in the detection of the mechanical center position O2.
[0064]
On the other hand, in the magnetic bearing device described above, the exciting current of the first Y-axis electromagnets (17c) and (18c) is increased relative to the rest by the amount of gravity acting on the rotating body (2). The above problems do not occur.
[0065]
Also in the conventional method shown in FIG. 5, the excitation current of the second Y-axis electromagnets (17c) and (18c) has a value I2 that is larger by the amount of gravity acting on the rotating body (2), as indicated by the broken line in the figure. By doing so, the above problems can be eliminated.
[0066]
By rotating the rotating body (2) by driving the motor (7) with the rotating body (2) supported in a non-contact manner at the mechanical center position by the magnetic bearings (3), (4), and (5), as described above. The rotation of the rotating body (2) can be stopped by stopping the driving of the motor (7). Then, after the rotation of the rotating body (2) is stopped, the driving of the magnetic bearings (3), (4) and (5) is stopped, and the excitation current of each electromagnet (16), (17) and (18) is set to zero. As a result, the magnetic bearings (3), (4), and (5) are not supported, and the rotating body (2) is supported by the protective bearings (10) and (11). Further, when rotating the rotating body (2) supported by the protective bearings (10) and (11) in a non-contact manner in this way, the mechanical center position obtained first is set as the target position. Then, the magnetic bearings (3), (4), and (5) are controlled.
[0067]
When the rotation of the rotating body (2) is stopped and supported by the protective bearings (10) and (11) as described above, the protective bearings (10) and (11) are not worn or damaged.
[0068]
However, the rotating body (2) rotating at high speed may come into contact with the inner rings (16b) and (17b) of the protective bearings (10) and (11) due to mistakes in use or abnormalities in the control system. In addition, when the power supply to the magnetic bearings (3) (4) (5) and the motor (7) is stopped due to a power failure or the like while the rotating body (2) is rotating, the rotating body ( 2) is received by the protective bearings (10) and (11), gradually decelerates, and eventually stops rotating. In such a case, the inner rings (16b) and (17b) of the protective bearings (10) and (11) come into contact with the rotating body (2) rotating at a high speed, rotate at a high speed, and from the rotating body (2). Due to the large force, the protective bearings (10) and (11) are greatly worn and may be damaged.
[0069]
Therefore, in the above magnetic bearing device, the rotation body (2) supported by the protective bearings (10) (11) is again supported by the magnetic bearings (3), (4), and (5). Before rotating, the abnormality of the protective bearings (10) and (11) is detected. This is almost the same as the abnormality detection after obtaining the mechanical center position in the radial direction described above. That is, first, the rotating body (2) is supported at the axial center of the axial direction first obtained by the axial magnetic bearing (3), and the radial direction of the protective bearings (10) and (11) described previously is as follows. Anomaly detection is performed. As a result, if there is no abnormality, the rotating body (2) is supported at the radial mechanical center position first obtained by the radial magnetic bearings (4) and (5), and the protective bearing (10) described above. Abnormality detection in the axial direction of (11) is performed. Then, only when there is no abnormality in any of them, the rotating body (2) is supported in a non-contact manner at the mechanical center position that is first obtained and rotated.
[0070]
In addition, even if it is not when starting a magnetic bearing apparatus for the first time, a mechanical center position can also be newly calculated | required as mentioned above as needed.
[0071]
Although the inner rotor type magnetic bearing device is shown in the above embodiment, the present invention can also be applied to an outer rotor type magnetic bearing device.
[0072]
In the above embodiment, a horizontal magnetic bearing device is shown. However, the present invention can also be applied to a vertical magnetic bearing device. In the case of a vertical magnetic bearing device, the X axis and Y axis, which are radial control axes, are arranged horizontally, and the Z axis, which is an axial control axis, is arranged vertically. Therefore, when determining the mechanical center position in the radial direction, it is not necessary to consider the gravity acting on the rotating body, and it is not necessary to provide the above difference in the excitation current of the electromagnet of the radial magnetic bearing.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view showing a configuration of a main part of a magnetic bearing device to which the present invention is applied.
FIG. 2 is a longitudinal sectional view of the same.
FIG. 3 is a cross-sectional view of the same.
4 is a block diagram showing an example of an electrical configuration of the magnetic bearing device of FIG. 1. FIG.
FIG. 5 is an explanatory view showing a conventional method for obtaining a radial mechanical center position of a magnetic bearing device.
FIG. 6 is an explanatory view showing an example of a method according to the present invention for obtaining a radial mechanical center position of a magnetic bearing device.
7 is a view showing the center position of the magnetic bearing device with respect to the sensor in the method of FIG. 6 and the position of the rotating body detected at each point of the moving process for moving the rotating body along the inner peripheral surface of the inner ring of the protective bearing. It is explanatory drawing which shows the center position and the mechanical center position of the radial direction calculated | required from these.
[Explanation of symbols]
(2) Rotating body
(3) Axial magnetic bearing
(4) (5) Radial magnetic bearing
(6) Position detection device
(8) Electromagnet controller
(10) (11) Protective bearing
(10a) (11a) Outer ring
(10b) (11b) Inner ring
(12) Axial position sensor
(16a) (16b) Axial electromagnet
(17a) (17b) (17c) (17d) Radial electromagnet
(18a) (18b) (18c) (18d) Radial electromagnet
(19a) (19b) (19c) (19d) Radial position sensor
(20a) (20b) (20c) (20d) Radial position sensor

Claims (1)

A plurality of sets of magnetic bearings having a plurality of electromagnets for non-contact support of the rotating body in the axial direction and the radial direction, a position detecting means having a plurality of position sensors for detecting the axial and radial positions of the rotating body, the position Electromagnet control means for controlling the electromagnets of the magnetic bearings based on the position detection result by the detection means, and the rotary body in the limit position of the movable range by regulating the movable range in the axial direction and the radial direction of the rotary body In a magnetic bearing device provided with a protective bearing comprising a rolling bearing that mechanically supports
One circumferential position of the circumferential surface of the rotating body in the rotation stopped state is brought into contact with one circumferential position of the circumferential surface of the protective bearing facing this, and this contact point is circumferential direction of the circumferential surface of the protective bearing. Means for successively moving, means for detecting the radial position of the center of the rotating body from the position detection results by the position detecting means at a plurality of points in the moving process, and the rotating body at each point in the moving process A magnetic bearing device comprising means for calculating a radial mechanical center position of the rotating body with respect to the protective bearing from a detection result of a radial position of the center of the magnetic bearing.

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