JP2000027863A - Controller for magnetic levitation rotary device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and a cost by controlling plural magnetic levitation rotary devices by a single control part. SOLUTION: A controller simultaneously controls plural magnetic levitation rotary devices P (P1, P2...) having a rotary body 3, the displacement detecting part 4 for outputting displacement signals by detecting displacement of the rotary body 3 and plural sets of controlling magnetic bearings 6, 7, 8 for supporting the rotary body 3 in a noncontact state by plural electromagnets. The controller has a switching circuit 31 for successively outputting the displacement signals from the respective magnetic levitation rotary devices P (P1, P2...) at prescribed time intervals in a switching system and the control part 32 for holding this until the displacement signals from the corresponding magnetic levitation rotary devices P (P1, P2...) are outputted from the switching circuit 31 in the next place by outputting an electromagnet control signal for controlling the electromagnets of the corresponding magnetic levitation rotary devices P (P1, P2...) on the basis of a displacement signal from the switching circuit 31 every time when output of the switching circuit 31 is switched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for a magnetic levitation rotating device. In this specification, a magnetic levitation rotating apparatus is a magnetic body in a non-contact manner supported by a control type magnetic bearing such as a pump body of a turbo molecular pump using a magnetic bearing used in a semiconductor manufacturing apparatus or the like. Refers to a device that is rotated by an electric motor.

[0002]

2. Description of the Related Art As a turbo-molecular pump, a pump main body in which a rotating body (rotor) constituting the pump is magnetically supported in a non-contact manner by an electromagnet of a control type magnetic bearing and is rotated at a high speed by an electric motor, and a controller for controlling the pump body (Pump control unit) is known. The pump main body is provided with a displacement detection unit that detects a displacement of the rotating body and outputs a displacement signal, and the displacement detection unit is provided with a plurality of displacement sensors. The controller is provided with a control unit that outputs an electromagnet control signal for controlling the electromagnet based on the displacement signal.

For example, a semiconductor manufacturing apparatus is often operated by connecting a plurality of turbo molecular pumps to one vacuum chamber. However, in the case of the conventional turbo-molecular pump, one controller is required for one pump body, and particularly in the case of a small pump, it is disadvantageous in terms of space and cost.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and to control a plurality of magnetic levitation rotating devices with one control unit, thereby reducing the size and reducing the cost. An object of the present invention is to provide a control device for a rotating device.

[0005]

According to the present invention, there is provided a control device for a magnetic levitation rotating apparatus, comprising: a rotating body; a displacement detecting section for detecting a displacement of the rotating body to output a displacement signal; A control device for simultaneously controlling a plurality of magnetic levitation rotating devices having a plurality of sets of control type magnetic bearings for supporting a body at a predetermined target position in a non-contact manner by magnetic attraction of a plurality of electromagnets, wherein A switching circuit for sequentially switching and outputting a displacement signal from each of the magnetic levitation rotating devices at intervals; and a corresponding magnetic levitation rotating device corresponding to a switching signal from the switching circuit each time the output of the switching circuit is switched. A control unit that outputs an electromagnet control signal for controlling the electromagnet and holds the displacement signal from the corresponding magnetic levitation rotating device until the next switching signal is output from the switching circuit; And it is characterized in that it comprises.

The switching circuit sequentially switches and outputs the displacement signals from the plurality of magnetic levitation rotating devices, and the control unit controls the corresponding magnetic levitation based on the displacement signal from the switching circuit every time the output of the switching circuit is switched. An electromagnet control signal for controlling the electromagnet of the rotating device is output and held until the displacement signal from the corresponding magnetic levitation rotating device is output from the switching circuit next time. A plurality of magnetic levitation rotating devices can be controlled. For this reason, it is possible to reduce the total space and cost of the plurality of magnetic levitation rotating devices and the control device. In addition, since a single control unit controls a plurality of magnetic levitation rotating devices, it is possible to simultaneously start and stop the respective magnetic levitation rotating devices, thereby simplifying the overall configuration. Furthermore, it is possible to centrally manage and monitor a plurality of magnetic levitation rotating devices simply by accessing a single control unit.

The control section is preferably constituted by digital processing means capable of executing a software program. As such digital processing means, for example, MPU
(Microprocessor), digital signal processor, etc. are used. A digital signal processor (Digital Signal Processor) refers to dedicated hardware that inputs a digital signal, outputs a digital signal, is capable of software programming, and is capable of high-speed real-time processing. Hereinafter, this is abbreviated as “DSP”.

If the control section is constituted by digital processing means capable of performing a software program, the functions of the control section as described above can be easily realized by the software program.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a control device for a pump body of a plurality of turbo-molecular pumps will be described below with reference to the drawings.

As shown in FIG. 1, a plurality of devices (in this example, four
Pump body (magnetic levitation rotating device) (P1) (P2) (P3) (P
In 4), one control device (1) is electrically connected by a cable. Note that the pump bodies are collectively referred to by a symbol (P), and when it is necessary to distinguish them, the first pump bodies (P
1), the second pump body (P2), the third pump body (P3), and the fourth pump body (P4).

Each pump body (P) has a similar structure, and FIG. 1 schematically shows only the structure of the first pump body (P1). FIGS. 2 and 3 show an example of a specific configuration of a main part of the pump body (P).

The pump body (P) is of a vertical type in which a vertically rotating body (3) rotates inside a vertically cylindrical casing (2). In the following description, the control axis (axial control axis) in the axial direction (vertical direction) of the rotating body (3)
Two control axes (radial control axes) in the radial direction (horizontal direction) orthogonal to the axis and orthogonal to each other are defined as an X axis and a Y axis.

The pump body (P) includes a displacement detector (4) for detecting displacement of the rotating body (3) in the axial and radial directions and outputting a displacement signal. A set of axial magnetic bearings (6) for contact and support, two sets of upper and lower radial magnetic bearings (7) and (8) for radially non-contact support of the rotating body (3), and high-speed rotation of the rotating body (3) Of the built-in type electric motor (10) and the rotating body (3) in the axial and radial directions, and the rotating body (3) can no longer be supported by the magnetic bearings (6) (7) (8) Rotary body (3) at the extreme position of the movable range at times
Upper and lower protective bearings (touchdown bearings) (11) and (12) are provided as regulating means for mechanically supporting the bearing.

The displacement detector (4) includes one axial displacement sensor (13) for detecting an axial displacement of the rotating body (3),
It includes two sets of upper and lower radial displacement sensor units (14) (15) for detecting radial displacement of the rotating body (3), and a sensor circuit (16).

The axial magnetic bearing (6) is composed of a pair of axial electromagnets (26) arranged so as to sandwich a flange (3a) integrally formed below the rotating body (3) from both sides in the Z-axis direction.
a) The axial electromagnet provided with (26b) is collectively referred to by reference numeral (26).

The two sets of radial magnetic bearings (7) and (8) are arranged at a predetermined interval vertically above the axial magnetic bearing (6), and the motor (10) is arranged between them. Have been. The upper radial magnetic bearing (7)
A pair of radial electromagnets (27a) and (27b) arranged to sandwich (3) from both sides in the X-axis direction and a pair of radial electromagnets (27a) and (27b) arranged to sandwich the rotating body (3) from both sides in the Y-axis direction Radial electromagnets (27c) and (27d) are provided. These radial electromagnets are collectively referred to by reference numeral (27). Similarly, the lower radial electromagnet (8) also has two pairs of radial electromagnets (28a) (28b) (28c) (28d).
It has. These radial electromagnets are also collectively referred to by reference numeral (28).

The axial displacement sensor (13) includes a rotating body (3)
And outputs a distance signal proportional to the distance (gap) with respect to the lower end surface of the rotating body (3).

The upper radial displacement sensor unit (14)
Are arranged near the upper radial magnetic bearing (7), and are arranged so as to sandwich the rotating body (3) from both sides in the X-axis direction in the vicinity of the electromagnets (27a) and (27b) in the X-axis direction. A pair of radial displacement sensors (29a) and (29b), and rotating bodies from both sides in the Y-axis direction near the electromagnets (27c) and (27d) in the Y-axis direction
(3) A pair of radial displacement sensors arranged to sandwich
(29c) and (29d) are provided. These radial displacement sensors are collectively referred to by reference numeral (29). Similarly, the lower radial displacement sensor unit (15) is disposed near the lower radial magnetic bearing (8), and has two pairs of radial displacement sensors (30).
a) (30b), (30c) and (30d). These radial displacement sensors are also collectively referred to by reference numeral (30). Each of the radial displacement sensors (29) and (30) outputs a distance signal proportional to the distance from the outer peripheral surface of the rotating body (3).

The sensor circuit (16) includes each of the displacement sensors (13) (29)
(30), and based on the output of each displacement sensor (13) (29) (30), the displacement of the rotating body (3) in the Z-axis direction, as well as the upper and lower radial displacement sensor units (14) (15) of the displacement in the X-axis direction and the Y-axis direction by amplifying operation in the portion, and outputs a displacement signal D ₁ is a result of the calculation to the control unit (1). The displacement signal, as described above, the displacement signal in the Z-axis direction, as well as the displacement signal of the X-axis and Y-axis direction are included in two vertical positions, in Figure 1, representative of these by D ₁ Is shown. Similarly, the displacement signal from the second pump body (P2) is
_2, the displacement signal from the third pump body (P3) in D _3, 4
A displacement signal from the pump body (P4) are shown representatively respectively D _4. Note that the displacement signals are also collectively referred to as D.

Electromagnets (26) (27) (28), Displacement sensors (13) (29)
(30) and the sensor circuit (16) are fixed to the casing (4).

The control device (1) comprises a switching circuit (31), a controller (32) constituting a control section, and four amplifier circuits (A1) (A2) (A3) (A3) corresponding to the respective pump bodies (P). A4), and an inverter (33). Note that the amplifier circuit
(A).

A switching circuit (31) composed of a multiplexer IC or the like receives a displacement signal D from each pump body (P) and, as described later in detail, switches each pump body (P) at predetermined time intervals. ) Are sequentially switched and output to the controller (32). A displacement signal which is an output signal of the switching circuit (31) and an input signal of the controller (32) is represented by a symbol I.

Although not shown, the controller (32) includes a DSP, an EPROM as digital processing means capable of performing software programming, a flash memory as a nonvolatile storage device, an AD converter, a DA converter, an operation panel, and the like. Is provided. The EPROM has a DSP
And the like are stored. The flash memory contains magnetic bearings (6) to (8) for each pump body (P).
And the like, which can be rewritten from an external personal computer or the like communicably connected to the controller (32) via communication software. Note that the processing program and the control parameters may be rewritten from the operation panel.

The displacement signal I from the switching circuit (31) is input to the DSP via the AD converter, and the DSP receives the displacement signal I, and based on the signal, the magnetic bearings (6) to (8) of each pump body (P). Each electromagnet
(26) (27) (28) Excitation current signal (electromagnet control signal)
Is output to the corresponding amplifier circuit (A) via the DA converter. The exciting current signal which is an output signal from the controller (32) to the first amplifier circuit (A1) will be representatively shown by reference numeral O _1. Similarly, the second amplifier circuit (A
The excitation current signal to 2) is represented by O ₂ , the excitation current signal to the third amplification circuit (A3) is represented by O ₃ , and the excitation current signal to the fourth amplification circuit (A4) is represented by O _4. I do. Note that these excitation current signals are also collectively referred to by the symbol O. Each of the amplifier circuits (A) transmits an exciting current based on the exciting current signal O from the controller (32) to the corresponding magnetic bearing (6) of the pump body (P).
(7) The electric power is supplied to the electromagnets (26), (27), and (28) of (8), whereby the rotating body (3) is supported in a non-contact manner at a predetermined target position.

The controller (32) also transmits a rotation speed command signal (motor control signal) to the motor (10) to an inverter.
(33), and the inverter (33) controls the rotation speed of the motor (10) of each pump body (P) based on this signal. And, as a result, the rotating body (3) is a magnetic bearing (6) (7)
While the motor is supported non-contact at the target position by (8),
It is rotated at high speed by (10). When the motor (10) is an induction motor, the motors of a plurality of pump bodies (P)
(10) can be driven by one inverter (33).
However, it is also possible to provide one inverter for each pump body (P).

Next, referring to the time chart of FIG.
The operations of the switching circuit (31) and the controller (32) will be described in more detail.

In FIG. 4, (a) shows displacement signals I, (b), (C) and (d) input from the switching circuit (31) to the controller (32).
And (e) are the first excitation current signal O ₁ from the controller (32) to the first amplification circuit (A1), the second excitation current signal O ₂ to the second amplification circuit (A2), and the third amplification circuit (A3). to) the third excitation current signals O ₃ and the fourth fourth excitation current signal O ₄ to the amplifier circuit (A4)
, And the horizontal axis represents time t.

As shown in FIG. 4A, the switching circuit (31)
Are the first displacement signal D ₁ from the displacement detector (4) of the first pump body (P1), the second displacement signal D ₂ from the second pump body (P2), and the third displacement signal D ₂ from the third pump body (P3). The third displacement signal D ₃ and the fourth displacement signal D ₄ from the fourth pump body (P4) are sequentially converted into a predetermined time Δt determined by the sampling time of the DSP in this order.
And outputs it as a displacement signal I to the controller (32). More specifically, Δt from the time point to to t1
During the period, the first displacement signal D ₁ is applied to the Δt from the time t1 to the time t2.
During the period, the second displacement signal D _{2 is applied} to the time Δt from the time t2 to the time t3.
During the period, the third displacement signal D ₃ is output from the time t3 to the time Δt4 from time t3.
During this period, the fourth displacement signal D ₄ is output. The same applies to time t4 and thereafter.

The controller (32), the input signal I at the time point to is switched to the first displacement signal D _1, as shown in FIG. 4 (b), based on this, the magnetic of the first pump body (P1) bearing (6) (7) electromagnet (8) (26) (27) calculates the excitation current value with respect to (28), the exciting current signal O ₁₀ a first corresponding thereto
Output to the exciting current signal O ₁ first amplifying circuit (A1).
Then, then between the input signal I to the time point t4 switching to the first displacement signal D _1, holds the first excitation current signal O ₁ to O _10, the first displacement input signal I at time t4 again signals D ₁
Is switched to a new exciting current signal O ₁₄ based on this.
The first output as an exciting current signal O ₁ to the first amplifier circuit (A1), which is then input signal I is held until time t8 when switched to the first displacement signal D _1.

Similarly, when the input signal I switches to the second displacement signal D ₂ at time t 1, the controller (32)
As shown in FIG. 4 (c), based on this, the exciting current value for the electromagnets (26) (27) (28) of the magnetic bearings (6) (7) (8) of the second pump body (P2) is calculated. operation, and outputs the excitation current signal O ₂₁ corresponding thereto to the first excitation current signal O ₂ second amplifier circuit (A2). Then, the input signal I is the second displacement signal D ₂
The second excitation current signal O ₂ is held at O ₂₁ until time t5 when the input signal I is switched to the second time t5.
When switched to the displacement signal D _2, a new excitation current signal O ₂₅ based on this output as the second excitation current signal O ₂ in the second amplifier circuit (A2), then the input signal I is a second displacement signal this hold up time of switching to the D _2.

Similarly, when the input signal I switches to the third displacement signal D ₃ at the time point t 2, the controller (32)
As shown in FIG. 4 (d), based on this, the exciting current value for the electromagnets (26) (27) (28) of the magnetic bearings (6) (7) (8) of the third pump body (P3) is calculated. operation, and outputs the excitation current signal O ₃₂ corresponding thereto to a third excitation current signal O ₃ third amplifier circuit (A3). Then, the input signal I is the third displacement signal D ₃
The third excitation current signal O ₃ is held at O ₃₂ until time t6 when the input signal I is switched to the third time.
When switched to the displacement signal D _3, a new excitation current signal O ₃₆ based on this output as the second excitation current signal O ₃ to the third amplifier circuit (A3), then the input signal I is a third displacement signal this hold up time of switching to D _3.

Similarly, when the input signal I switches to the fourth displacement signal D ₄ at the time t 3, the controller (32)
As shown in FIG. 4 (e), based on this, the exciting current value for the electromagnets (26) (27) (28) of the magnetic bearings (6) (7) (8) of the fourth pump body (P4) is calculated. operation, and outputs the excitation current signal O ₄₃ corresponding thereto to the fourth amplifier circuit (A4) as a fourth excitation current signal O _4. Then, the input signal I is the fourth displacement signal D ₄
The fourth excitation current signal O ₄ is held at O ₄₃ until time t7 when the input signal I is switched to the fourth time at time t7.
When switching to the displacement signal D ₄ , a new exciting current signal O ₄₇ based on this is output to the fourth amplifier circuit (A 4) as a fourth exciting current signal O ₄ , which is then input to the fourth amplifier circuit (A 4). hold up time of switching to D _4.

As a result, the magnetic bearing (6) of each pump body (P)
(7) (8) is controlled by the controller (32) with a holding time that is four times Δt. The control sampling time Δt of the DSP is usually about 0.1 msec, but may be determined based on the number of pump bodies (P) to be controlled and the time required for control processing.

In the control device (1), the switching circuit (31)
Sequentially outputs the displacement signals D from the plurality of pump bodies (P), and the controller (32) outputs the displacement signal D from the switching circuit (31) every time the output signal I of the switching circuit (31) is switched. Magnetic bearings of the pump body (P) corresponding to the signal I (6) (7)
An excitation current signal O for controlling the electromagnets (26), (27), and (28) of (8) is output to the corresponding amplifier circuit (A), and the displacement signal D from the corresponding pump body (P) is output. Next, since it is held until output from the switching circuit (31), a single controller (32) can control a plurality of pump bodies (P). For this reason, it is possible to reduce the total space and cost including the plurality of pump bodies (P) and the control device (1). In addition, since a single controller (32) controls a plurality of pump bodies (P), the pump bodies (P) can be started and stopped at the same time, and the overall configuration can be simplified. Further, centralized management and monitoring of a plurality of pump bodies (P) can be performed only by accessing one controller (32).

The number and configuration of the pump body (P), the configuration of the control device (1), and the like are not limited to those of the above-described embodiment, and can be appropriately changed.

In the above embodiment, an example in which the control device according to the present invention is applied to control of a pump body of a turbo molecular pump has been described. However, the present invention is also applicable to a lathe having a spindle using a magnetic bearing, Magnetic levitation rotation that has a magnetic bearing that supports a rotating body and an electric motor that rotates this rotating body, such as a machine tool such as a machining center or a grinding machine, a fluid machine such as a compressor or blower that uses a magnetic bearing, or a flywheel. It can be applied to any device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a plurality of pump bodies and a control device thereof according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a specific configuration of a main part of the pump body.

FIG. 3 is a cross-sectional view of the same.

FIG. 4 is a time chart showing a temporal change of an input signal and an output signal of a controller.

[Explanation of symbols]

(1) Control device (3) Rotating body (4) Displacement detector (6) Axial magnetic bearing (7) (8) Radial magnetic bearing (26a) (26b) (26c) (26d) Axial electromagnet (27a) (27b ) (27c) (27d) Radial electromagnet (28a) (28b) (28c) (28d) Radial electromagnet (31) Switching circuit (32) Controller (control unit) (P1) (P2) (P3) (P4) Pump body (Magnetic levitation rotating device)

Claims (1)

[Claims] 1. A rotating body, a displacement detecting section for detecting a displacement of the rotating body and outputting a displacement signal, and a plurality of non-contact supporting the rotating body at a predetermined target position by magnetic attraction of a plurality of electromagnets. A control device for simultaneously controlling a plurality of magnetic levitation rotating devices having a set of control type magnetic bearings, the switching device sequentially switching and outputting displacement signals from the magnetic levitation rotating devices at predetermined time intervals. Circuit, and outputs an electromagnet control signal for controlling the electromagnet of the magnetic levitation rotating device corresponding to the displacement signal from the switching circuit each time the output of the switching circuit is switched, and A control unit for holding a displacement signal from the magnetic levitation rotating device until the displacement signal is output from the switching circuit next time.