JPS63138410A - Noncontact supporting method - Google Patents

Abstract

PURPOSE:To eliminate generation of heat and to attain reduction of the power amplifier capacity and stability of control jobs, by defining the magnetic poles approximate to each other as the same poles between a permanent magnet of the fixed side and a permanent magnet of the movable side which are set via a fixed gap. CONSTITUTION:At least two pairs of permanent magnets 311/321 and 312/322 are provided at the fixed and movable sides near an electromagnet. The fixed and movable sides of these pairs of magnets are set opposite to each other in the same pole via a minute gap. The repulsive power of first pair of magnets is set opposite to that of second pair and both pairs are positioned in the same direction as the attracting direction of the electromagnet. Therefore those magnets 311-322 only function to secure no mutual contact at the movable side and therefore can start even with a slight current. Thus the restoring force due to the repulsive power works despite the eccentricity is caused to the magnetic pole of one side by the external force. As a result, the large capacity is not required for a power amplifier and furthermore the generation of heat is eliminated with addition of a zero current control loop.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a non-contact supporting method using magnetic force among methods for supporting a rotating body or a linear conveying body.

[Conventional technology]

BACKGROUND ART Magnetic bearings that support non-contact using magnetic force have come to be used in rotating bodies or linear drive systems in order to reduce bearing loss or as a method to withstand use in special environments.

A first method for constructing the movable part is to attract the movable part in opposite directions using two electromagnets. In this case, if a bias current is supplied to increase rigidity, heat is generated due to copper loss and iron loss, which is a problem when used in a vacuum. Additionally, it was necessary to increase the current capacity of the power amplifier to provide a steady current.

Therefore, in order to reduce the capacity of the power amplifier, the winding of the electromagnet is divided into two, and one of the windings is connected in series with one winding of the other electromagnet, so that one power amplifier can generate a constant current. The method of supplying
220, etc.), but since copper loss and iron loss occur in the same way, the problem of heat in vacuum remains.

On the other hand, in order to solve the problem of heat generation, for example,
-As seen in Publication No. 37323, a method has been proposed in which a permanent magnet is installed in the magnetic path of the electromagnet and the magnetic flux of the permanent magnet replaces the magnetic flux caused by the electromagnet's bias current, but no current is supplied to the electromagnet. At the time, the moving parts are attracted by the magnetic attraction force of the permanent magnet, so when starting up, it is necessary to supply enough current to generate the attraction force to overcome this attraction, which requires a power amplifier with a correspondingly large capacity. there were. In addition, the magnetic attraction force of a permanent magnet is inversely proportional to the square of the gap, so it is nonlinear and unstable, and the control loop using electromagnets is required to have the ability to compensate for this, so the control system can be stabilized. I couldn't get enough of it.

[Problem that the invention seeks to solve]

This invention was made in view of the above problems, and aims to eliminate the problem of heat generation, reduce the capacity of the power amplifier, and stabilize the control area so that it can be used in a vacuum. This also makes it possible.

[Means for solving problems]

As a method for this, in addition to the conventional method of magnetically attracting the movable part using two electromagnets in opposite directions and levitating it in a non-contact manner, at least two sets of permanent magnets are installed on the fixed side and the movable side near the electromagnets. be. Further, the fixed side and the movable side of the paired permanent magnets are arranged to face each other with the same polarity through a small gap. Another method is to arrange the first set of repulsive forces and the second set of repulsive forces in opposite directions and in the same direction as the attracting direction of the electromagnet.

[For production]

With this arrangement, when looking only at the permanent magnet, it acts to keep the movable parts out of contact, so it can be started with a small amount of current, and even if the magnetic pole is eccentric to one side due to an external force, it will remain permanently Since the restoring force is generated by the repulsive force of the magnet, there is no need to increase the capacity of the power amplifier. In addition, by providing a zero current control loop,
It is also possible to make the steady state current zero, copper loss and iron loss zero, and heat generation zero.

〔Example〕

FIG. 1 shows the configuration of an embodiment in which the present invention is applied to a rotating body. 1 is a rotating shaft, and two radial bearings 21 and 22 are provided at separate positions in the axial direction. It is possible. A thrust bearing that restricts movement in the axial direction and a motor that applies rotational force to the rotating shaft 1 are not shown.

The radial bearing 21 (or 22) consists of an iron core and a winding, and a stator 211 is fixed to a frame (not shown).
(or 221), and a rotor 212 fixed to the rotating shaft 1 via the stator 211 (or 221) and a minute gap.
(or 222), a displacement sensor (not shown) provided near the stator 211 (or 221) that detects the minute gap, and a displacement sensor (not shown) that detects the minute gap, and a displacement sensor (not shown) that detects the minute gap.
1 (or 221), and a bearing controller (not shown) that supplies current to 1 (or 221), and is controlled so that the minute gap is constant.

On the other hand, a repulsion type radial bearing using a permanent magnet is provided near the shaft end side of the radial bearing 21 (or 22), and a fixed side permanent magnet 311 fixed to a frame (not shown) is provided.
(or 321) and the fixed permanent magnet 311 (or 3
21) and a rotating side permanent magnet 312 (or 322) fixed to the rotating shaft via a small gap.

Fixed side and rotating side permanent magnets 311 (or 321), 3
12 (or 322) are magnetized in the radial direction, and the parts that face each other through a small gap have the same polarity, so that even if the permanent magnet bearing 31 (or 32) is used alone, it can be supported without contact in the radial direction. is possible.

Note that the direction of the magnetizing force of the permanent magnet 31 (or 32) may be NS in the axial direction.

FIG. 2 shows a control block diagram, where XS+Xf is the command value of the minute gap and the output of a displacement sensor (not shown), which is the detection signal of the minute gap. A difference signal is obtained by the comparator receiving these signals, and is used as an input signal to the displacement control compensator 5.

Then, the power amplifier 6t sends a s2-<command, and a current of 1. , supplies Ig.

Also, the difference between the detection signals fl+12 of the currents It and Iz is obtained as if by the comparator, and the command signal t, (=O)
It is compared with and is input to the zero current control compensator 4. Then, the displacement command x,
is being output.

In such a configuration, if the displacement detection signal Xf has a different value with respect to the displacement command
2 to supply currents It and Ig to the stator, displace the rotating shaft by magnetic attraction force, and generate a displacement detection signal X.
, constitutes a constant displacement control loop that operates so that , is equal to the displacement command X,.

Furthermore, if the current detection signal i, has a different value from the zero current command signal i, (=O), the zero current control phase compensator 4 that has received the difference is connected to the constant displacement control loop. It gives a displacement command x1, works so that the stator current becomes zero, and constitutes a zero current control loop.

With such a configuration, the operation when a step external force in the radial direction is applied to the rotating shaft will be described.

Immediately before an external force is applied, the force is balanced only by the permanent magnet, a displacement command x1 corresponding to that position is given to the displacement control loop, and the stator currents It, It are zero and balanced.

When a radial displacement occurs on the rotating shaft due to an external step force,
Permanent magnets have weak attenuation but a restoring force. Regarding the displacement control loop, since the displacement detection signal Xt is different from the command value x1, the displacement control phase compensator 5 works,
The differentiator included there also listens to the attenuation well, and the radial displacement of the rotating shaft 1 is restored, and the displacement detection signal Xr changes to the command value
, is equal to .

However, in this state, a current that balances the step external force is supplied to the electromagnet, so the current detection signal if is no longer zero, and the zero current control phase compensator 4 operates to correct the displacement command x. It is. When the displacement command X is corrected to a position where the external force being applied and the repulsive force of the permanent magnet are balanced, the current supplied to the electromagnet ii becomes zero, so the input to the zero current control phase compensator 4 becomes zero. Therefore, it becomes a steady state.

Next, we will explain what happens at startup. In the permanent magnet radial bearing shown in FIG. 1, although it floats in the radial direction, there is no restriction in the thrust direction, so it is displaced in the thrust direction and stops against an auxiliary bearing (not shown).

If a permanent magnet is also used in the thrust direction and it is also of a repulsive type, it is often thought that the permanent magnet will levitate completely with only the permanent magnet, but it is known that this is impossible.
This is proven by aw. Therefore, in this case as well, it means that something is touching and stopping.

In either case, the attraction force does not increase as the gap becomes smaller, as is the case when an attraction type permanent magnet is used, but instead it is repelled and stops at a distant position, so when starting up, the rotation axis The force required to return the magnet to the center of the fixed side is small, and the starting current supplied to the electromagnet is small. Therefore, there is no need for an oversized power amplifier.

The above discussion has been about rotating bodies, but it goes without saying that the same applies to linear types as well.

〔Effect of the invention〕

As mentioned above, regardless of whether a steady external force is applied or not, the constant external force and the repulsive force of the permanent magnet are controlled to a balanced position, so the current of the electromagnet is always zero.

Therefore, there is no copper loss, no iron loss, and no heat generation, which has the effect of making it possible to use it in a vacuum.

Furthermore, the starting special current is small, and even during levitation, the permanent magnet alone provides positive bearing rigidity, so the capacity of the power amplifier can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram when the present invention is applied to a rotating body, and FIG. 2 is a control block diagram thereof. 1... Rotating shaft 21... First radial bearing 211... Stator 212... Rotor 22... Second radial bearing 221... Stator 222... Rotor 31... First Permanent magnet bearing 311...Stator 312...Rotor 32...Second permanent magnet bearing 321...Stator 322...Rotor 4...Zero current control phase compensator 5...Displacement Control phase compensator 61...first power amplifier 62...second power amplifier ■,...supply current It...supply current i,...detection signal 12 of ■1... 1□ detection signal i,...Zero current command signal (normally zero) xl...Displacement command signal X,...Displacement detection signal i,...Current detection signal 1...Rotating shaft 21. ...First radial bearing 211...Stator 212...Rotor 22...Second radial bearing 221...Stator 222...Rotor 31...First permanent magnet bearing 311... Stator 312...Rotor 32...Second permanent magnet bearing 321...Stator 322...Rotor 4...Zero current control phase compensator 5...Displacement control phase compensator 61...・First power amplifier 62...Second power amplifier Fig. 1 Fig. 2

Claims (6)

[Claims] (1) At least two electromagnets arranged in opposite directions on the fixed side, a yoke provided on the movable side with a certain gap between them and the electromagnets, and a displacement sensor that detects relative displacement between the fixed side and the movable side. and a displacement controller that receives the output signal of the displacement sensor and supplies current to the at least two electromagnets, wherein at least two permanent magnets are arranged on the fixed side near the fixed side electromagnet. A permanent magnet is provided on the movable side with a fixed gap between the permanent magnet and the permanent magnet, and the magnetic poles of the fixed side permanent magnet and the movable side permanent magnet that are provided across the fixed gap are the same polarity. A non-contact support method characterized by: (2) Claim 1 characterized in that the magnetic path created by the electromagnet and the magnetic path created by the permanent magnet do not interfere with each other.
Non-contact support method described in section. (3) The non-contact support method according to claim 1, wherein the movable side is a rotating body. (4) The non-contact support method according to claim 1, wherein the movable side is a linear conveyor. (5) A zero current control loop is provided outside the constant displacement control loop, and a displacement command for a position where the current of the electromagnet becomes zero is given to the displacement controller. Contact support method. (6) The non-contact support method according to claim 1, wherein the displacement controller includes means for linearizing magnetic attraction force.