CN110486380B

CN110486380B - Stator-free tooth heteropolar permanent magnet bias hybrid radial magnetic bearing

Info

Publication number: CN110486380B
Application number: CN201910611239.5A
Authority: CN
Inventors: 江梓丹; 洪俊杰; 严柏平; 王富立; 冯君璞; 邓雪微; 贾智海
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2019-07-08
Filing date: 2019-07-08
Publication date: 2021-02-19
Anticipated expiration: 2039-07-08
Also published as: CN110486380A

Abstract

The invention relates to the technical field of magnetic bearings, in particular to a stator-free tooth heteropolar permanent magnet bias hybrid radial magnetic bearing which comprises a stator, a rotor, permanent magnets, control coils and a rotating shaft, wherein the rotor is arranged in the stator, a working air gap is formed between the rotor and the stator, the rotating shaft is fixedly arranged on the rotor, the rotor rotates relative to the stator, at least two permanent magnets are arranged on the stator in a central symmetry manner, the control coils wound on the stator are arranged between the adjacent permanent magnets, and 4 control coils are arranged on the stator in a central symmetry manner. The whole structure is symmetrical and simple, the loss of the stator core is reduced, the radial size is reduced, and the space utilization rate is improved.

Description

Stator-free tooth heteropolar permanent magnet bias hybrid radial magnetic bearing

Technical Field

The invention relates to the technical field of magnetic bearings, in particular to a stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing.

Background

With the rapid development of modern industry, high-speed and ultra-high-speed motors are increasingly widely used. However, the requirement for the performance of the bearing is higher and higher due to the increase of the rotating speed of the motor, and the traditional mechanical bearing cannot meet the requirement. In contrast, because there is no mechanical contact between the stator and rotor of the magnetic bearing, the rotor of the magnetic bearing can reach a very high operating speed, and has the advantages of small mechanical wear, low energy consumption, long service life, no lubrication, no pollution and the like, and is particularly suitable for special application occasions such as high speed, vacuum, ultra-clean and nuclear, and therefore has attracted increasing attention.

The magnetic bearing can be divided into an active magnetic bearing (electromagnetic bearing), a passive magnetic bearing (permanent magnet bearing) and a hybrid magnetic bearing (magnetic bearing with permanent magnet and electromagnetism mixed), and the hybrid magnetic bearing is also called a permanent magnet bias hybrid magnetic bearing; the permanent magnet bias hybrid magnetic bearing has the advantages of both a passive magnetic bearing and an active magnetic bearing, fully utilizes the permanent magnet to provide a bias magnetic field, and reduces the standby loss of the system; the existing homopolar permanent magnet bias hybrid magnetic bearing is not beneficial to improving the critical rotating speed of a rotor because the permanent magnet bias magnetic flux of the magnetic bearing has an axial trend and the axial length of the bearing is long. Although the heteropolar permanent magnet bias hybrid radial magnetic bearing does not have the problem, the current structure still has some defects. For example, the electric excitation magnetic circuit penetrates through the permanent magnet, so that not only is larger excitation current required and power consumption is larger, but also the permanent magnet is repeatedly magnetized and demagnetized, and the reliability of the permanent magnet is reduced; or for the decoupling of the permanent magnetic circuit and the electric excitation magnetic circuit, an auxiliary air gap is adopted beside the permanent magnet as the electric excitation magnetic circuit. This may cause the permanent magnet to lose a large magnetomotive force or a serious magnetic flux leakage; and nearly all permanent magnet biased hybrid magnetic bearings have stator teeth to wind electromagnetically excited windings; therefore, the radial size of the bearing is inevitably large, and if the size of the permanent magnet biased hybrid magnetic bearing is further reduced, a novel stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing needs to be developed to meet the trend of industrial miniaturization.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing which is symmetrical and simple in overall structure, reduces the loss of a stator core, reduces the radial size and improves the space utilization rate.

In order to solve the technical problems, the invention adopts the technical scheme that: a stator-free tooth heteropolar permanent magnet bias hybrid radial magnetic bearing comprises a stator, a rotor, permanent magnets, control coils and a rotating shaft, wherein the rotor is arranged in the stator, a working air gap is formed between the rotor and the stator, the rotating shaft is fixedly arranged on the rotor, the rotor rotates relative to the stator, at least two permanent magnets are arranged on the stator in a centrosymmetric manner, the control coils wound on the stator are arranged between the adjacent permanent magnets, and at least two control coils are arranged on the stator in a centrosymmetric manner.

In the device, the structure is symmetrical, so that the permanent magnet bias magnetic circuit and the control magnetic circuit of the device are also symmetrically distributed in the structure, when the rotor is positioned in the central position and the control current of the control coil is zero, the bias magnetic flux density of the working air gap is equal, and the resultant force applied to the rotor is zero. If the rotor is disturbed to cause the change of the bias magnetic flux in the upper working air gap and the lower working air gap, the magnetic flux is superposed with the bias magnetic flux in the working air gap to pull the rotor back to the balance position, so that the rotor can be kept at the balance position no matter which direction the rotor is disturbed. In addition, the device reduces the arrangement of stator teeth, reduces the stator loss, has a simpler structure, reduces the radial size of the magnetic bearing, improves the space utilization rate and enlarges the application range. The path of the permanent magnetic circuit is short, the control magnetic circuit does not pass through the permanent magnet, an additional air gap does not exist, the required control magnetomotive force is small, and the efficiency is high; the irreversible demagnetization of the permanent magnet can not be caused by adjusting the exciting current, and the reliability of the system is improved. The control magnetic circuit and the permanent magnet bias magnetic circuit have good decoupling performance, and are beneficial to the design of a control system.

Furthermore, the control coil comprises a forward control coil and a reverse control coil, and the forward control coil and the reverse control coil are connected in series and have opposite winding directions.

Furthermore, the opposite magnetic poles of the adjacent permanent magnets are homopolar. Wherein, the permanent magnet is made of sintered neodymium iron boron. Two adjacent permanent magnets have the same size and opposite magnetizing directions.

Furthermore, the permanent magnets are of a cuboid structure, and every two adjacent permanent magnets are vertically embedded into the stator.

Furthermore, the stator is provided with a plurality of openings, and the permanent magnets are embedded into the openings.

Furthermore, the wall thickness of the open pore is 0.8-1.2 mm. Preferably 1 mm.

Furthermore, a groove is formed in the stator, and the control coil is wound in the groove. Wherein the control coil is used for glue filling treatment.

Further, the working air gap is smaller than 1 mm.

Furthermore, the stator and the rotor are formed by axially laminating multiple layers of non-oriented silicon steel sheets. The rotating shaft is made of high-strength steel, is fixedly arranged at the rotating center of the rotor and rotates together with the rotor.

Furthermore, the power amplifier is also included, and the control coil is electrically connected with the power amplifier.

Further, a radiating fin is arranged on the periphery of the stator and used for radiating heat of the stator.

Compared with the prior art, the invention has the beneficial effects that:

the device reduces the arrangement of stator teeth, reduces the stator loss, has simpler structure, reduces the radial size of the magnetic bearing, improves the space utilization rate and enlarges the application range. The path of the permanent magnetic circuit is short, the control magnetic circuit does not pass through the permanent magnet, an additional air gap does not exist, the required control magnetomotive force is small, and the efficiency is high; the irreversible demagnetization of the permanent magnet can not be caused by adjusting the exciting current, and the reliability of the system is improved. The control magnetic circuit and the permanent magnet bias magnetic circuit have good decoupling performance, and are beneficial to the design of a control system. The device has symmetrical integral structure, can meet the requirements of different bearing capacities in radial directions, can meet the requirement of a horizontal system for bearing the gravity of the rotor, and can also be applied to a vertical system.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic view of a permanent magnet bias circuit in one embodiment of the present invention;

FIG. 3 is a schematic diagram of the control circuit of the present invention in one embodiment;

fig. 4 is a schematic view of a composite magnetic circuit according to an embodiment of the present invention.

Detailed Description

The present invention will be further described with reference to the following embodiments. Wherein the showings are for the purpose of illustration only and are shown by way of illustration only and not in actual form, and are not to be construed as limiting the present patent; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. based on the orientation or positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but it is not intended to indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and are not to be construed as limiting the present patent, and the specific meaning of the terms may be understood by those skilled in the art according to specific circumstances.

Example 1:

as shown in fig. 1, the stator-free tooth heteropolar permanent magnet biased hybrid radial magnetic bearing comprises a stator 3, a rotor 4, a permanent magnet 1, a control coil and a rotating shaft 5, wherein the stator 3 and the rotor 4 are both in an annular structure, and the stator 3 and the rotor 4 are formed by axially laminating multiple layers of non-oriented silicon steel sheets. The permanent magnet 1 is made of sintered neodymium iron boron, and the rotating shaft 5 is made of high-strength steel.

Wherein, rotor 4 is arranged in stator 3, is provided with the working clearance that is less than 1mm between rotor 4 and the stator 3, and rotor 4 can rotate for stator 3. At least two permanent magnet 1 centrosymmetries set up on stator 3, and in this embodiment, permanent magnet 1 is provided with 4, and permanent magnet 1 is regular cuboid structure, and every permanent magnet 1 size is the same, and the relative magnetic pole of adjacent permanent magnet 1 is the same, therefore adjacent permanent magnet 1's the opposite direction of magnetizing. Specifically, 4 openings for embedding the permanent magnets 1 are formed in the stator 3, the adjacent permanent magnets 1 are vertically embedded into the openings, and the wall thickness of each opening is 0.8-1.2 mm. Preferably 1 mm. The 4 permanent magnets 1 are respectively arranged on the stator 3 in a central symmetry mode, and the magnetizing direction adopts circumferential magnetizing. A heat sink is provided on the periphery of the stator 3 for dissipating heat from the stator 3.

All be provided with control coil between adjacent permanent magnet 1, in this embodiment, control coil is provided with 4, and every control coil sets up respectively in the centre of two adjacent permanent magnets 1, and control coil is the same with the distance between two adjacent permanent magnets 1. The control coil of the present embodiment is composed of a forward control coil 2-1 and a reverse control coil 2-2, wherein the forward control coil 2-1 and the reverse control coil 2-2 are connected in series and have opposite winding directions.

A groove for installing a control coil is provided on the stator 3, and the forward control coil 2-1 and the reverse control coil 2-2 are wound in the groove of the stator 3. And the control coil is processed through glue pouring, and is electrically connected with the power amplifier and an external power supply in sequence, and the output power of the coil is controlled by the power amplifier.

In this embodiment, the permanent magnetic circuit of the stator-less 3-tooth heteropolar permanent magnet biased hybrid radial magnetic bearing adopts a radial magnetic circuit, and the specific direction thereof is as shown in fig. 2: the N pole of the permanent magnet 1 → the stator 3 → the working air gap 6 → the rotor 4 → the stator 3 → the S pole of the permanent magnet 1.

In the present embodiment, the radial distribution of the electrically excited magnetic circuit of the stator-less 3-tooth heteropolar permanent magnet biased hybrid radial magnetic bearing is taken as an example of the radial section of the stator 3 in fig. 3. The paths of the electric excitation magnetic flux generated by the control coil in the Y-axis direction are as follows: stator 3 pole → working air gap 6 → rotor 4 → working air gap 6 → stator 3. Because the magnetic resistance of the permanent magnet 1 is large, the control magnetic flux does not pass through the permanent magnetic pole, and the demagnetization of the permanent magnet 1 by the control magnetic flux can be avoided.

The working principle of the stator-free 3-tooth heteropolar permanent magnet bias hybrid radial magnetic bearing is as follows:

due to the symmetrical structure, when the rotor 4 is located at the central position and the control current is zero, the air gap bias flux density is equal, and the resultant force applied to the rotor 4 is zero. Assuming that the rotor 4 is subjected to a-Y disturbing force to change the bias flux of the upper and lower air gaps, the-Y direction is large and the + Y direction is small, and at this time, a control flux is generated on the Y-direction control coil as shown in fig. 4, and the control flux is superposed with the bias flux in the air gaps to increase the flux in the air gaps of the rotor 4+ Y, and the flux in the-Y air gap is reduced to generate a resultant force of attraction force to + Y to pull the rotor 4 back to the equilibrium position. Similarly, the control can keep the rotor 4 in the equilibrium position regardless of the external disturbance of the rotor 4 in the X direction and the Y direction.

The device reduces the arrangement of 3 teeth of the stator, reduces the loss of the stator 3, has simpler structure, reduces the radial size of the magnetic bearing, improves the space utilization rate and enlarges the application range. The path of the permanent magnetic circuit is short, the control magnetic circuit does not pass through the permanent magnet 1, an additional air gap does not exist, the required control magnetomotive force is small, and the efficiency is high; the irreversible demagnetization of the permanent magnet 1 can not be caused by adjusting the exciting current, and the system reliability is improved. The control magnetic circuit and the permanent magnet bias magnetic circuit have good decoupling performance, and are beneficial to the design of a control system. The device has symmetrical integral structure, can meet the requirements of different bearing capacities in radial directions, can meet the requirement of a horizontal system for bearing the gravity of the rotor 4, and can also be applied to a vertical system.

Example 2:

the present embodiment is similar to embodiment 1, except that in the present embodiment, the stator 3 and the rotor 4 are both formed by axially laminating silicon steel sheets, and the thickness is 0.2mm, 0.35mm or 0.5mm, so as to reduce eddy current loss inside the iron core; the control coils are divided into four groups, are respectively wound in the grooves of the stator 3 and are controlled by the power amplifier, and the number of turns of 2-1 of the forward control coil is 80; the working air gap 6 is set to be 0.5mm, and the rotating shaft 5 is made of high-strength No. 45 steel; the permanent magnet 1 is made of sintered neodymium iron boron material with high magnetic performance so as to generate enough bias magnetic flux; the permanent magnets 1 are processed into a cuboid sheet structure and are embedded in the openings of the stator 3, every two adjacent permanent magnets 1 are vertically arranged, the magnetizing direction adopts circumferential magnetizing, and the two adjacent permanent magnets 1 are the same in size and opposite in magnetizing direction; the permanent magnet bias magnetic circuit and the control magnetic circuit are on the same plane and are radial magnetic circuits. The device is suitable for paired use in specific engineering application.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A stator-free tooth heteropolar permanent magnet bias hybrid radial magnetic bearing is characterized by comprising a stator (3), a rotor (4), permanent magnets (1), control coils and a rotating shaft (5), wherein the rotor (4) is arranged in the stator (3), a working air gap (6) is arranged between the rotor (4) and the stator (3), the rotating shaft (5) is fixedly arranged on the rotor (4), the rotor (4) rotates relative to the stator (3), at least two permanent magnets (1) are arranged on the stator (3) in a central symmetry manner, the control coils wound on the stator (3) are arranged between the adjacent permanent magnets (1), and the at least two control coils are arranged on the stator (3) in a central symmetry manner; the control coil comprises a forward control coil (2-1) and a reverse control coil (2-2), wherein the forward control coil (2-1) and the reverse control coil (2-2) are connected in series, and the winding directions are opposite.

2. A stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing as claimed in claim 1 in which the opposing poles of adjacent permanent magnets (1) are homopolar.

3. The stator-free tooth heteropolar permanent magnet biased hybrid radial magnetic bearing according to claim 1, wherein the permanent magnets (1) are rectangular structures, and the adjacent permanent magnets (1) are embedded in the stator (3) in pairs and perpendicular to each other.

4. The stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing according to claim 3, wherein the stator (3) is provided with a plurality of openings in which the permanent magnets (1) are embedded.

5. The stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing of claim 4 wherein the openings have a wall thickness of 0.8-1.2 mm.

6. The stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing of claim 1, wherein the stator (3) is provided with grooves in which the control coils are wound.

7. A stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing as claimed in claim 1 in which the working air gap (6) is less than 1 mm.

8. The stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing according to claim 1, wherein the stator (3) and the rotor (4) are axially laminated by multiple layers of non-oriented silicon steel sheets.

9. The stator-free heteropolar permanent magnet biased hybrid radial magnetic bearing of claim 1 further comprising a power amplifier, the control coils being electrically connected to the power amplifier.