WO2019245226A1 - Thrust magnetic bearing using flux switching - Google Patents

Abstract

Disclosed is a thrust magnetic bearing using flux switching. A thrust magnetic bearing, according to one embodiment of the present invention, is mounted on one side of a rotor having a rotation shaft formed in one direction to control the axial oscillations of the rotor by levitating a disc-shaped rotor collar which is coupled to the rotor in the direction perpendicular to the rotation shaft, and comprises a ring-shaped permanent magnet inserted and fixed in the rotor collar, an electromagnetic coil provided to be spaced from the permanent magnet by a predetermined distance, and a stator core for covering the electromagnetic coil. Accordingly, the thrust magnetic bearing can be flux-switched to form a magnetic flux of the magnetic bearing in one direction only, and can secure approximately twice the thrust force compared to the same volume of existing thrust magnetic bearing.

Description

Axial Magnetic Bearings with Magnetic Flux Switching

The present invention relates to an axial magnetic bearing, and more particularly to an axial magnetic bearing using magnetic flux switching.

Conventional general bearings use mechanical rolling bearings, and they have problems such as noise, dust, and life due to mechanical friction caused by contact between the rotor and the bearings. In order to solve the problems caused by friction, research on non-contact magnetic bearings has been continuously conducted.

Magnetic bearings are stably supporting the injured body by two magnetic poles facing each other attracting the injured body to each other and by adding or subtracting the magnetic force according to the positional change of the injured body.

Conventional axial magnetic bearings have a method of arranging an electromagnet coil and adjusting the amount of current supplied to the electromagnet coil to support the floating body (the background art of patent document 1, the electromagnet method), in which case the deflection magnetic force In addition, the power is wasted by supplying a constant bias current irrespective of the injured body, and the electromagnetic force must be generated only by the coil, which increases the amount of coils. There is a problem.

On the contrary, in the case of the method of including a permanent magnet together with an electromagnet coil as an axial magnetic bearing to solve the above problem (Background art of Patent Document 1, the electromagnet and the permanent magnet method), power waste and magnetic bearing size problems are solved. However, depending on the placement of the permanent magnets, an attractive force between the permanent magnets and the rotor and rotor collar is generated, which is unnecessary in the radial direction in a structure including a radial magnetic bearing and an axial magnetic bearing requiring triaxial injury. The generation of force acts as a disturbance associated with the control of the radial magnetic bearing, thereby causing a problem of power waste, and there is a problem of requiring a larger size radial magnetic bearing to cover such disturbance.

In addition, even when the arrangement of the permanent magnet in the axial direction as in Patent Document 1, there is still disturbance in the radial direction in the structure, the cost and difficulty of processing increases as the number of permanent magnets increases, the magnetic flux by the permanent magnet Only the attraction force by the magnetic flux of any one of the permanent magnets separated and disposed above and below is generated.

Patent Document 1: Republic of Korea Patent Publication No. 10-1552350

Embodiments of the present invention, in the axial magnetic bearing having an electromagnet coil and a permanent magnet, by designing an axial magnetic bearing capable of magnetic flux switching to form the magnetic flux of the magnetic bearing in only one direction, the same as the existing axial magnetic bearing To provide an axial magnetic bearing that can secure about twice the thrust of the volume.

In addition, since the same current is supplied to the electromagnet coils provided symmetrically on the axial magnetic bearing, the magnetic flux switching is performed. Therefore, two current drivers required for the electromagnet coil provided in the axial magnetic bearing are operated as one current driver. It is intended to provide this possible axial magnetic bearing.

In addition, according to the structural disturbance in the radial direction acting in accordance with the permanent magnet arrangement of the existing axial magnetic bearing, additional control is required through the radial magnetic bearing, but the axial vibration can be independently controlled by eliminating the radial disturbance. An axial magnetic bearing can be provided.

It is installed on one side of the rotor having a rotating shaft formed in one direction according to an embodiment of the present invention to control the axial vibration of the rotor by floating a rotor-shaped collar of the disk type coupled to the rotor in a direction perpendicular to the rotating shaft The axial magnetic bearing is inserted into and fixed to the rotor collar, a ring-shaped permanent magnet having a radially magnetized bias magnetic flux, provided with a predetermined distance spaced apart from the permanent magnet, is provided on top of the permanent magnet An electromagnet coil including an upper coil and a lower coil provided below the permanent magnet, a stator core including an upper stator core covering the upper electromagnet coil and a lower stator core covering the lower coil, and the upper and lower coils. Includes a single current driver connected to the current supply to supply the same current Concentrate the magnetic flux in any one of the upper coil or the lower coil of the inner magnetic flux direction is the same direction as the bias magnetic flux direction of the permanent magnet, the outer surface of the rotor collar and the outer surface of the stator core is The upper coil and the lower coil are disposed on the same plane in the axial direction of the rotor, and both coils are wound in the same direction so that both coils are in the same direction when the same current is applied to the upper and lower coils from the current driver. Thrust occurs.

In addition, according to an embodiment of the present invention, the permanent magnet may be provided through the rotor collar in the direction of the rotation axis of the rotor.

In addition, according to an embodiment of the present invention, it may include a gap sensor provided on one side of the rotor collar to measure the gap according to the axial vibration of the rotor.

Embodiments of the present invention relate to an axial magnetic bearing for controlling the axial vibration of the rotor, the axial magnetic bearing having an electromagnet coil and a permanent magnet capable of magnetic flux switching to form the magnetic flux of the magnetic bearing in only one direction It is designed to secure about twice the thrust of the same volume compared to the existing axial magnetic bearing.

In addition, the permanent magnet is inserted and fixed to the rotor collar to remove the disturbance in the radial direction to generate the thrust only in the axial direction, radial in accordance with the radial disturbance in the structure including the radial magnetic bearing and the axial magnetic bearing Can be eliminated by the axial magnetic bearing structure of the present invention.

1 is a cross-sectional view illustrating a magnetic bearing system including an axial magnetic bearing according to an embodiment of the present invention.

2 is a cross-sectional view for explaining a magnetic bearing system including a conventional axial magnetic bearing.

3 is a view for explaining the magnetic flux direction of the axial magnetic bearing by the permanent magnet in the state that no current is applied to the electromagnet coil.

4 and 5 are views for explaining the flow of current in the electromagnetic coil and the direction of the magnetic flux in the axial magnetic bearing for generating the lower thrust.

6 and 7 are views for explaining the flow of current in the electromagnet coil for generating the upper thrust and the direction of the magnetic flux in the axial magnetic bearing.

It is installed on one side of the rotor having a rotating shaft formed in one direction according to an embodiment of the present invention to control the axial vibration of the rotor by floating a rotor-shaped collar of the disk type coupled to the rotor in a direction perpendicular to the rotating shaft The axial magnetic bearing is inserted into and fixed to the rotor collar, a ring-shaped permanent magnet having a radially magnetized bias magnetic flux, provided with a predetermined distance spaced apart from the permanent magnet, is provided on top of the permanent magnet An electromagnet coil including an upper coil and a lower coil provided below the permanent magnet, a stator core including an upper stator core covering the upper electromagnet coil and a lower stator core covering the lower coil, and the upper and lower coils. Includes a single current driver connected to the current supply to supply the same current Concentrate the magnetic flux in any one of the upper coil or the lower coil of the inner magnetic flux direction is the same direction as the bias magnetic flux direction of the permanent magnet, the outer surface of the rotor collar and the outer surface of the stator core is The upper coil and the lower coil are disposed on the same plane in the axial direction of the rotor, and both coils are wound in the same direction so that both coils are in the same direction when the same current is applied to the upper and lower coils from the current driver. Thrust occurs.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are presented to sufficiently convey the spirit of the present invention to those skilled in the art. The present invention is not limited to the embodiments presented herein but may be embodied in other forms. The drawings may omit illustrations of parts not related to the description in order to clarify the present invention, and may be exaggerated to some extent in order to facilitate understanding.

1 is a cross-sectional view illustrating a magnetic bearing system including an axial magnetic bearing according to an embodiment of the present invention.

The axial magnetic bearing according to an embodiment of the present invention, the disk-shaped rotor is installed on one side of the rotor (1) having a rotation axis formed in one direction and coupled to the rotor (1) in a direction perpendicular to the rotation axis The collar 2 is floated to control the axial vibration of the rotor 1.

Referring to FIG. 1, the axial magnetic bearing includes a permanent magnet 10, an electromagnet coil 20, and a stator core 30.

The axial magnetic bearing is formed through the rotor collar (2) including the rotating shaft and the rotating shaft, and a ring-shaped permanent magnet (10), an electromagnet coil (20) and a stator core (30) surrounding the rotating shaft. The rotor collar 2 coupled to the rotor 1 in a direction perpendicular to the rotation axis is magnetically floated to support the axial vibration of the rotor 1.

The permanent magnet 10 is provided in a ring shape that is inserted and fixed to the rotor collar (2). The permanent magnet 10 is magnetized in a radial direction, that is, in a direction perpendicular to the direction of the rotation axis of the rotor 1, and has a deflection magnetic force in the radial direction.

In the case of the axial magnetic bearing of the electromagnet type that does not include the permanent magnet 10, since the deflection magnetic force must be applied to the rotor collar 2 in advance, a constant current must be supplied for the deflection magnetic force. The deflection magnetic force eliminates the need for this current supply and is economical.

For example, the permanent magnet 10 may be provided through the rotor collar 2 in the direction of the rotation axis of the rotor 1. On the contrary, the permanent magnet 10 may be provided in a form in which two permanent magnets separated at positions corresponding to the upper and lower surfaces of the rotor collar 2 are inserted and fixed. In this case, the two permanent magnets The magnetization directions may be arranged in the same manner.

The electromagnet coil 20 is provided spaced apart from the permanent magnet 10 by a predetermined distance.

The electromagnet coil 20 is provided above and below the permanent magnet 10.

The electromagnet coil 20 includes an upper coil 21 provided on the upper portion of the permanent magnet 10 and a lower coil 22 provided on the lower portion of the permanent magnet 10.

The upper coil 21 and the lower coil 22 are provided in a ring shape by winding a plurality of coils, and coils are wound in the same direction in both the upper and lower coils 21 and 22. Therefore, when the same current is applied to both the upper and lower coils 21 and 22, thrust is generated in both coils in the same direction.

The stator core 30 covers the electromagnet coil 20.

The stator core 30 includes an upper stator core covering the upper surface and both sides of the upper coil 21, and a lower stator core covering the lower surface and both sides of the lower coil 22.

The upper coil 21 and the upper stator core at the upper part, and the lower coil 22 and the lower stator core at the lower part of the permanent magnet 10 are perpendicular to the rotation axis of the rotor 1. It may be provided symmetrically.

And a current driver 40 connected to the upper and lower coils 21 and 22 to supply a current. For example, the current driver 40 may be connected to the upper and lower coils 21 and 22 from one current driver to supply the same current. The current driver 40 supplies a current to the electromagnet coil 20 according to the driving current information provided by the other controller.

Referring to the operation of the axial magnetic bearing, when current is supplied from the current driver 40 to the upper and lower coils 21 and 22, magnetic flux is generated in the electromagnet coil 20.

The rotor collar 2 is a floating body by the magnetic flux by the permanent magnet 10 and the magnetic flux by the electromagnet coil 20 and the upper coil 21 and the upper stator core and the lower coil 22. ) And the space between the lower stator cores.

In the axial magnetic bearing including a conventional permanent magnet and an electromagnet coil, the permanent magnet is radially spaced apart from the rotor and the rotor collar in a radial distance, whereby the permanent magnet is a radial structure of the rotor and the rotor An attractive force is generated between the collar and additional force in the radial direction.

In a structure including a radial magnetic bearing and an axial magnetic bearing in which the radial and axial triaxial floatation of the rotor 10 is required, the generation of unnecessary force in the radial direction due to the arrangement of such permanent magnets results in a radial magnetic It acts as a disturbance associated with the control of the bearing, and further control in the radial direction is required.

Alternatively, the permanent magnet 10 of the axial magnetic bearing according to an embodiment of the present invention can be inserted and fixed to the rotor collar 2 to block the occurrence of the radial disturbance as described above, independently Directional vibration can be controlled.

For example, an axial magnetic bearing according to an embodiment of the present invention is provided at the upper and lower sides of the side of the rotor collar 2, in this case, the outer surface of the rotor collar 2 and the stator core ( The outer surface of 30 may be disposed on the same plane in the axial direction of the rotor (1).

The magnetic flux direction change and the magnetic flux switching according to the current supply to the electromagnet coil will be described later in detail with reference to FIGS. 2 to 7.

The axial magnetic bearing of the present invention includes a gap sensor 50 which is provided on one side of the rotor collar 2 and measures the gap according to the axial vibration of the rotor 1.

The gap sensor 50 is disposed in the same direction as the rotation axis of the rotor 1 to detect vibration of the rotor 1 in the axial direction, and although not shown, is connected to the current driver 40 through a control unit. The driving current of the current driver 40 is calculated and transmitted based on the displacement information of the gap sensor 50. Accordingly, axial vibration of the rotor 1 may be minimized.

2 is a cross-sectional view for explaining a magnetic bearing system including a conventional axial magnetic bearing. 3 is a view for explaining the magnetic flux direction of the axial magnetic bearing by the permanent magnet in the state that no current is applied to the electromagnet coil. 4 and 5 are views for explaining the flow of current in the electromagnetic coil and the direction of the magnetic flux in the axial magnetic bearing for generating the lower thrust. 6 and 7 are views for explaining the flow of current in the electromagnet coil for generating the upper thrust and the direction of the magnetic flux in the axial magnetic bearing.

2 to 7, the magnetic flux direction change of the magnetic flux switching and the axial magnetic bearing according to an embodiment of the present invention will be described in detail.

As shown in FIG. 2, in the case of the axial magnetic bearing of the conventional electromagnet type, different current drivers are connected to the upper electromagnet coil and the lower electromagnet coil to supply different currents for generating the upper thrust and the lower thrust. In the case of axial magnetic bearings of electromagnets and electromagnets, there is a waste of unnecessary power due to radial disturbance caused by permanent magnet arrangement.

The axial magnetic bearing of the present invention is an axial magnetic bearing including a permanent magnet 10 and an electromagnet coil 20, and the permanent magnet 10 is inserted and fixed to the rotor collar 2 to exclude radial disturbances. Therefore, only the axial magnetic bearing of the present invention can independently control the axial direction.

Referring to FIG. 3, a deflection magnetic force, that is, a bias magnetic flux (BMF) magnetized to the permanent magnet 10 in a state in which no current is supplied to the electromagnet coil 20, is indicated by an arrow.

For example, the permanent magnet 10 of FIG. 3 is magnetized in a desired direction and has a deflection magnetic force (BMF) according to the magnetized direction. In this case, the basic magnetic flux MF by the magnet induced by the deflecting magnetic force of the permanent magnet 10 is formed in both stator cores 30.

For example, but not limited to this, the permanent magnet 10 of FIG. 3 magnets outward from the rotor 1 to have a deflection magnetic force. On the contrary, although not shown, the permanent magnet 10 may be magnetized in the opposite direction to the opposite direction to have the deflection magnetic force in the opposite direction, in which case it may be reversed from the description below, which may be appropriately modified at the level of ordinary skill in the art. will be.

For example, when the permanent magnet 10 has a deflection magnetic force outward from the rotor 1, in the case of the upper stator core, the basic magnetic flux MF is formed upward from the outer circumferential surface to the inner circumferential surface. In addition, in the case of the lower stator core, the basic magnetic flux MF is formed downward from the outer circumferential surface to the inner circumferential surface.

Accordingly, even when the same current is supplied to the upper and lower coils 21 and 22 by using one current driver, thrust may be generated only in a specific direction by using magnetic flux switching, as will be described later.

4 and 5, FIG. 5 is a perspective view of the electromagnet coil 20 of FIG. 4 separated from each other and illustrates a current flow and a thrust generation direction. When the electromagnet coil 20 of FIG. 5 is viewed from the top, the current direction and the thrust direction of the axial magnetic bearing in the state in which the current is applied in the clockwise direction of the electromagnet coil 20 in the form of a ring are shown.

The electromagnet coil 20 is provided in a ring shape by winding a plurality of coils. When the electromagnet coil 20 is viewed from the top, when a current is applied in a clockwise direction in a ring shape, thrust is generated downward in accordance with the law of the right hand screw. In FIG. 5, an arrow marked to rotate clockwise along the coil on the right side of the electromagnet coil 20 denotes an applied current direction, and an arrow marked vertically downward refers to a thrust F direction.

When the current is supplied to the electromagnet coil 20 in a counterclockwise direction, the magnetic flux (CF) direction inside the electromagnet coil 20 is formed from the outer circumferential surface to the inner circumferential surface downward from the cross section of the axial magnetic bearing in the axial direction.

Since the deflection magnetic force BMF of the permanent magnet 10 is formed outward from the rotor 1, the direction of the magnetic flux CF inside the upper coil 21 according to the current supply is the deflection of the permanent magnet 10. The magnetic flux MF formed along the upper stator core in a direction opposite to the magnetic force BMF direction does not pass through the permanent magnet 10. Therefore, the magnetic flux MF of the upper stator core is absorbed by the magnetic flux MF of the lower stator core along the magnetization direction of the permanent magnet 10.

Since the direction of the magnetic flux CF inside the lower coil 22 is the same as the direction of the magnetic flux BMF by the permanent magnet 10, all of the basic magnetic flux MF is transferred to the lower stator core by the permanent magnet 10. Is formed. That is, both the magnetic flux MF of the upper stator core and the lower stator core are formed in the lower stator core, and as the current applied to the electromagnet coil 20 increases, the magnetic flux MF is concentrated on the lower stator core so that the upper or When using any one of the magnetic flux (MF) of the lower stator core, the magnetic flux of about 2 times can be concentrated on one side, which can generate the same volume and twice the thrust of the same power as the conventional axial magnetic bearings. .

Referring to FIGS. 6 and 7, when the electromagnet coil 20 is viewed from the top, when a current is applied counterclockwise in a ring shape, thrust is generated in accordance with the law of the right hand screw.

In FIG. 7, an arrow marked to rotate in the counterclockwise direction along the coil on the left side of the electromagnet coil 20 denotes an applied current direction, and an arrow vertically indicated upward means a thrust F direction.

When a current is supplied to the electromagnet coil 20 in a clockwise direction, the magnetic flux (CF) direction inside the electromagnet coil 20 is formed from an outer circumferential surface to an inner circumferential surface upwardly in a cross section cut in the axial magnetic bearing.

Since the deflection magnetic force BMF of the permanent magnet 10 is formed outward from the rotor 1, the direction of the magnetic flux CF inside the lower coil 22 according to the current supply is the deflection of the permanent magnet 10. The magnetic flux MF formed along the lower stator core in a direction opposite to the magnetic force BMF direction does not pass through the permanent magnet 10. Therefore, the magnetic flux MF of the lower stator core is absorbed by the magnetic flux MF of the upper stator core along the magnetization direction of the permanent magnet 10.

Since the direction of the magnetic flux CF inside the upper coil 22 is the same as the direction of the magnetic flux BMF by the permanent magnet 10, all of the basic magnetic flux MF is transferred to the upper stator core by the permanent magnet 10. Is formed. That is, both the magnetic flux MF of the upper stator core and the lower stator core are formed in the upper stator core, and as the current applied to the electromagnet coil 20 increases, the magnetic flux MF concentrates on the upper stator core so that the upper or When using any one of the magnetic flux (MF) of the lower stator core, the magnetic flux of about 2 times can be concentrated on one side, which can generate the same volume and twice the thrust of the same power as the conventional axial magnetic bearings. .

Accordingly, the thrust may be generated only in any one of the upper and lower directions according to the supply direction of the electric current to the electromagnet coil 20. That is, the magnetic flux generated by the permanent magnet 10 and the direction of the magnetic flux generated by supplying current to the electromagnet coil 20 are controlled to facilitate the upward or downward direction of the axial magnetic bearing through magnetic flux switching. It can generate manpower.

As described above, the exemplary embodiments of the present invention have been described, but the present invention is not limited thereto, and a person skilled in the art does not depart from the spirit and scope of the following claims. It will be understood that various changes and modifications are possible in the following.

Claims (3)

In the axial magnetic bearing is installed on one side of the rotor having a rotation axis formed in one direction to float the disk-shaped rotor collar coupled to the rotor in a direction perpendicular to the rotation axis to control the axial vibration of the rotor, A ring-shaped permanent magnet inserted into and fixed to the rotor collar and having a radially magnetized bias magnetic flux; An electromagnet coil provided to be spaced apart from the permanent magnet at a predetermined distance and including an upper coil provided above the permanent magnet and a lower coil provided below the permanent magnet; A stator core comprising an upper stator core covering the upper electromagnet coil and a lower stator core covering the lower coil; And A current driver connected to the upper and lower coils to supply the same current; The magnetic flux is concentrated only on any one of the upper coil and the lower coil whose internal magnetic flux direction according to the current supply is the same as the bias magnetic flux direction of the permanent magnet, An outer surface of the rotor collar and an outer surface of the stator core are disposed on the same plane in the axial direction of the rotor, Both the upper coil and the lower coil are wound in the same direction, so that when the same current is applied to the upper and lower coils from the one current driver, both coils generate thrust in the same direction. The method of claim 1, The permanent magnet is axial magnetic bearing, characterized in that provided through the rotor collar in the direction of the rotation axis of the rotor. The method of claim 1, And a gap sensor provided at one side of the rotor collar to measure a gap according to the axial vibration of the rotor.

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