JPH048911A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To support a magnetic bearing device with an auxiliary bearing in a stable state even when abnormal vibration is generated on a rotating shaft by outputting a signal of a specific level when the output signal of a displacement sensor exceeds a set value and by adding between a phase compensating circuit and one power amplifier and exciting an electromagnet to attract the rotating shaft to one side. CONSTITUTION:A signal detected by displacement detection sensors 4a, 4b of a rotating shaft 1 is computed at a position deflection arithmetic circuit 7a to get difference between it and a position setter 6a. This output is compensated at a phase compensating circuit 8a, a comparing circuit 13a compares the output of the position deflection arithmetic circuit 7a and a standard setting circuit 14a and a specific direct current signal is output. Additionally, an electric power amplifier 9 flows a current which is larger than 10a by the output of the comparing circuit 13a to a coil 11a of an electromagnet 2a, and electromagnets 2b, 3b are excited in the Y axis direction in the same way. Accordingly, it is possible to support the rotating shaft 1 with an auxiliary bearing in a stable state without swinging by way of attracting the rotating shaft 1 to the side of the magnet 2a when abnormal vibration is generated on the rotating shaft 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic bearing device that holds a rotating shaft in a non-contact state.

(Prior Art) Conventionally, as this type of magnetic bearing device, one shown in FIG. 4, for example, has been provided. That is, 1 is a rotating shaft, and 2a, 3a, 2b, and 3b are electromagnets for holding the rotating shaft 1 at the reference position shown in the figure in a non-contact state. In this case, assuming that the X and Y axes are perpendicular to each other at the rotation center 0 of the rotation axis 1, the electromagnets 2g and 3a are arranged to face each other across the rotation axis 1 on the X axis, and the electromagnets 2b and 3
b are arranged on the Y-axis so as to be opposite to each other with the rotating shaft 1 narrowed therebetween. 4a and 4b are displacement sensors, which are arranged on the X l1ll Y axes, respectively, and detect the displacement of the rotating shaft 1 in the respective axial directions. 5a is a control circuit that performs control in the X-axis direction, and is configured as follows. That is, 6a is a position setter for setting the reference position of the rotating shaft 1, 7a is a position deviation calculation circuit to which signals are given from the position setter 6a and the displacement sensor 4a,
Based on these signals, a deviation signal corresponding to the deviation of the rotating shaft 1 from the reference position is output. 8a is a phase compensation circuit, which performs phase compensation through processing such as P, I, and D control based on the deviation signal from the position deviation calculation circuit 7a, and uses this as a control signal to power amplify W9a,
Excitation coil II of electromagnets 2a and 3g via 10a, respectively.
It is designed to be given to JL and 12a. Note that 5b is a control circuit that performs control in the Y-axis direction, and has the same configuration as the control circuit 5a. It outputs a control signal based on the signal output from the displacement sensor 4b, and controls the electromagnets 2b and 3.
b, excitation coils llb, 12b.

With such a configuration, the displacement sensors 4a, 4b and the control circuit 5a,
5b sends a control signal to the excitation coils lla and 12a of the electromagnets 2a, 3g, 2b, and 3b in order to correct the rotating shaft 1 to the reference position.
, llb, and 12b. As a result, the rotating shaft 1 is held at the reference position in a non-contact state.

By the way, the rotor will fall when the system is not operating or when an excessive load is applied to the rotating shaft.

At this time, an auxiliary bearing is installed to prevent the rotor and stator from coming into direct contact and being damaged. By setting the gap of this auxiliary bearing part to about 1/2 of the gap of the magnetic bearing part, the auxiliary bearing comes into contact first when the object falls.

If the rotor falls during high-speed rotation, a large force is applied, so special rolling bearings and sliding bearings are used.

(Problems to be Solved by the Invention) In a magnetic bearing device having such a configuration, when an excessive load is applied to the rotating shaft during high-speed rotation and the magnitude exceeds the controllable range, the load as shown in FIG. 3(a) As shown in the figure, the rotating shaft 1 falls onto the auxiliary bearing and swings around inside the auxiliary bearing, damaging the bearing due to the impact and causing the rotating shaft 1 to lose its mechanical balance. Furthermore, there is a problem in that it causes vibrations during rotation.

In order to solve this problem, as shown in Figure 5, when abnormal vibration occurs in the rotating shaft due to an excessive load or external force such as an earthquake, we stop energizing the electromagnet based on the output of the displacement sensor and rotate it. A thrust disk 16 provided on the shaft 1 is absorbed downward by a permanent magnet 17. Further, due to this suction force and gravity, the rotating shaft 1 moves downward, and the tapered surface 18 of the rotating shaft comes into pressure contact with the tapered surface 19 of the corresponding auxiliary bearing.

As a result, there is no gap between the rotating shaft 1 and the auxiliary bearing 20, and the rotating shaft 1 is supported by the auxiliary bearing 20 and can rotate without whirling (Japanese Patent Application Laid-Open No. 1983-1973-1).
190930).

However, this method requires a permanent magnet that attracts the thrust disk when the electromagnet is stopped, a rolling bearing with a tapered surface on the inner ring, and a rotating shaft with a corresponding tapered surface.

The present invention has been made in view of the above circumstances, and its purpose is to stabilize the rotating shaft when excessive load is applied to the rotating shaft during high-speed rotation and abnormal vibration occurs by making slight changes to the control circuit. To provide a magnetic bearing device supported by an auxiliary bearing.

[Structure of the Invention] (Means for Solving the Problems) A magnetic bearing device of the present invention is provided with a pair of electromagnets arranged to hold a rotating shaft in a non-contact state. A displacement sensor is provided to detect the displacement sensor, and a position deviation calculation circuit is provided to detect the deviation between the output signal from the displacement sensor and the output signal of the position setting device which sets the reference position of the rotating shaft. A comparison circuit is provided that outputs a DC signal corresponding to the deviation, sufficient to attract the rotating shaft before an excessive load is applied during operation and the rotating shaft becomes uncontrollable. The electromagnet is excited with DC current, and before it becomes uncontrollable and the rotating shaft contacts the auxiliary bearing, the rotating shaft is attracted to one of the electromagnets, and the rotating shaft is supported at one point on the auxiliary bearing to prevent the rotating shaft from whirling around. The feature is that it is configured with a control circuit that controls the electromagnet.

(Function) According to the magnetic bearing device of the present invention, when an excessive load is applied during high-speed operation or abnormal vibration occurs on the rotating shaft due to an external force such as an earthquake, the difference between the current position of the rotating shaft and the reference position A DC signal corresponding to the output voltage is output, and the electromagnet is DC-excited by this DC signal to attract the rotating shaft. As a result, the rotating shaft is supported at one point on the auxiliary bearing, and rotates stably without whirling.

(Embodiment) An embodiment in which the present invention is applied to a radial magnetic bearing will be described below with reference to FIGS. 1 to 3. The structural configuration is the same as the conventional example shown in FIG.

In the figure, 1 is a rotating shaft of a motor, etc., which is supported by an auxiliary bearing (not shown) when the motor is stopped. 2g, 3a
, 2b, and 3b are electromagnets for holding the rotating shaft 1 at the reference position shown in the figure in a non-contact state.

In this case, assuming that the X and Y axes are perpendicular to each other at the rotation center 0 of the rotation axis 1, the electromagnets 2b and 3 are arranged so as to face each other across the rotation axis l on the X axis.
b are arranged to face each other on the Y-axis with the rotating shaft 1 in between. 4a and 4b are displacement sensors, which are arranged on the X-axis and Y-axis, respectively, and
It detects and outputs displacement in the axial direction.

Now, next, the electrical configuration will be described. 5J! .

5b is a control circuit. These control systems perform control in the X-axis and Y-axis directions, respectively, and have similar configurations, and the control systems in the X-axis and Y-axis directions will be described in detail below.

6a is a position setting device for setting the reference position of the rotating shaft 1, and outputs a reference position signal Sr. 7a is this position setting device 6
This is a position deviation calculation circuit to which signals are given from a and the displacement sensor 4a, and outputs a deviation signal 5r-5x corresponding to the deviation of the rotating shaft 1 from the reference position based on the reference position signal Sr and the displacement sensor output signal Sx. . 8a is a phase compensation circuit, and the deviation symbol 5r-S from the position deviation calculation circuit 7a
Based on x, P, 1. Phase compensation is performed by processing such as D control. 13a is a comparison circuit, and position deviation calculation circuit 7a
, that is, when the magnitude of the deviation between the reference position signal S' and the displacement sensor output signal Sx exceeds the set value signal S given from the reference setter 14a, a DC signal SD of a predetermined level L is output.

9a is a power amplifier, and the electromagnet 2 on the displacement sensor 4a side
The sum of the output signal SP of the phase compensation circuit 8a and eight output signals of the comparator circuit 13a is amplified and given to the excitation coil lla of a. Although 10a is also a power amplifier,
This amplifies the output signal SP' of the phase compensation circuit 8a and supplies it to the excitation coil 12a of the electromagnet 3a. At this time, SP
The absolute values of and SP are always equal.

Similarly, for control in the Y-axis direction, a control signal is output based on the signal given from the displacement sensor 4b,
It is designed to be applied to excitation coils 11b and 12b of electromagnets 2b and 3b.

Next, the operation of this embodiment will be described with reference to FIGS. 2 and 3. In addition, regarding the action, the X-axis direction and the Y-axis direction
The control system in the axial direction is carried out in exactly the same way, so below:
Only the control system in the X-axis direction will be described.

As shown in FIG. 2, in the steady state, the position deviation calculation circuit 7
The deviation signal 5r-5x from a is approximately equal to zero, and the output signal SD of the comparison circuit 13a becomes zero. As a result, the signal 5A-SP+S given to the power amplifier 9a and IC1g
The absolute values of D and s,' become equal, and the rotation axis 1 is held stably. However, when an excessive load is applied during high-speed rotation and abnormal vibration occurs on the rotating shaft, the deviation signal 5r-3x from the position deviation calculation circuit 7a increases. At this time,
In the comparator circuit 13g, when the deviation signal 5r-Sx exceeds the set value signal SL as shown in FIG. The signal sD is added to the phase compensation circuit 8a. As a result, power width increasers 9a, 10! l
The signals 5A-SP+SD and SP' given to As shown in Figure (b), it is controlled to be attracted to the electromagnet 2a side. In this way, the comparison circuit 13g is provided in this embodiment, and when the magnitude of the deviation between the reference position signal Sr and the displacement sensor output signal Sx exceeds the set value by the set value signal SL from the reference setter 14a, the variation sensor The signal given to the excitation coil lla of the side electromagnet 2a is such that a signal SD of a predetermined level L is added to the output signal Sp of the phase compensation circuit 8a. As a result, a large suction force is applied to attract the rotating shaft 1 in one direction, so that the rotating shaft can rotate stably without whirling.

Note that the above embodiments can of course be applied to radial magnetic bearings.

[Effects of the Invention] According to the magnetic bearing device of the present invention, the following effects can be obtained. In other words, a comparator circuit is provided, and when the rotary shaft is greatly displaced and the output signal of the displacement sensor exceeds a set value, a comparison circuit is provided, which outputs a signal at a predetermined level when the rotation axis is largely displaced and the output signal of the displacement sensor exceeds the set value. The rotary shaft is sucked in one direction by adding the values between the two. As a result, unlike in the past, even if abnormal vibration occurs in the rotating shaft due to a slight change in the circuit, it can be stably supported by the auxiliary bearing.

[Brief explanation of drawings]

FIG. 1 is an overall structural diagram showing an embodiment of a magnetic bearing device according to the present invention, FIGS. 2 and 3 are action explanatory diagrams, and FIG. 4 is a diagram equivalent to FIG. 1 showing a conventional example. FIG. 5 is a structural diagram showing a conventional example. 1...Rotation axis. 2 a, 2 b, 3 a, 3 b---
-Electromagnet. 4a, 4b...Displacement sensor. 5a, 5b...control circuit. 7a...Position deviation calculation circuit. 13a... Comparison circuit, 20... Auxiliary bearing. Agent Patent Attorney Noriyuki Chika No. 71 Figure 2

Claims (1)

[Claims] A displacement sensor that detects the position of the rotating shaft, and an output signal from this displacement sensor and a reference position of the rotating shaft are set in the device including a pair of electromagnets arranged to hold the rotating shaft in a non-contact state. The position deviation calculation circuit detects the difference between the output signal of the position setting device and compares this position deviation signal with the set value signal to control the position before an excessive load is applied during operation and the control becomes uncontrollable. A comparison circuit outputs a DC signal large enough to cut off the signal in response to the deviation, and this DC signal excites the electromagnet with DC current, causing it to become uncontrollable and to one of the electromagnets before the rotating shaft contacts the auxiliary bearing. A magnetic bearing device comprising a control circuit that controls an electromagnet so as to prevent the rotating shaft from whirling by attracting the rotating shaft and supporting it at one point on an auxiliary bearing.