Active three-degree-of-freedom magnetic bearing, control method thereof, motor and compressor

Abstract

The present application provides an active three-degree-of-freedom magnetic bearing and its control method, motor and compressor. The active three-degree-of-freedom magnetic bearing includes a bearing rotor, including a rotor ring body on which a rotating shaft is mounted; a bearing stator, including a first bearing stator assembly and a second bearing stator assembly; the first bearing stator assembly applies a radial magnetic field to the rotor ring body to adjust the radial position of the rotor ring body; the second bearing stator assembly applies an axial magnetic field to the rotor ring body to adjust the axial position of the rotor ring body. The present application sets corresponding bearing stators in the radial and axial directions of the bearing rotor, with a high degree of integration, so that there is no need to assemble a thrust plate separately on the rotating shaft, the structure is more compact, the process is simplified, the bearing volume is effectively reduced, the rotating shaft length is shortened, the critical speed of the rotor is increased, and the operating stability of the magnetic suspension system is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of magnetic bearings, and specifically relates to an active three-degree-of-freedom magnetic bearing and a control method thereof, a motor, and a compressor. Background Art

[0002] Magnetic bearings use magnetic force to suspend a bearing rotor mounted on a rotating shaft, maintaining a non-contact state between the bearing rotor and the bearing stator. Therefore, magnetic bearings have the advantages of being wear-free, high-speed, high-precision, and long-life. Magnetic bearings can be divided into three categories based on their operating principle: active magnetic bearings, passive magnetic bearings, and hybrid magnetic bearings. Magnetic bearings are further divided into radial magnetic bearings and axial magnetic bearings based on their direction of action. Radial magnetic bearings adjust the radial position of the rotating shaft through electromagnetic force between them and the radial rotor, while axial magnetic bearings adjust the axial position of the rotating shaft through electromagnetic force between them and the thrust plate on the rotating shaft.

[0003] In a magnetic levitation system, radial magnetic bearings and axial magnetic bearings can be simultaneously configured at both ends of the rotating shaft, thereby achieving adjustment of the rotating shaft's position in three degrees of freedom (X, Y, and Z axes). However, independently configured radial and axial magnetic bearings have a low degree of integration and occupy the rotating shaft, resulting in a relatively large rotating shaft length, which is not conducive to improving the critical speed of the rotor. Of course, some existing technologies have also integrated radial and axial magnetic bearings into a three-degree-of-freedom magnetic bearing. However, the structural design of the radial and axial bearings in such three-degree-of-freedom magnetic bearings is not rational, resulting in the magnetic lines of force of the radial bearing and the magnetic lines of force of the axial bearing each forming a path through corresponding rotor components, such as the radial rotor or thrust plate, resulting in a low degree of integration. Summary of the Invention

[0004] Therefore, the present application provides an active three-degree-of-freedom magnetic bearing and its control method, motor and compressor, which can solve the problems of unreasonable structural design and low degree of integration in the three-degree-of-freedom magnetic bearing in the prior art.

[0005] In order to solve the above problems, the present application provides an active three-degree-of-freedom magnetic bearing, comprising:

[0006] The bearing rotor comprises a rotor ring body on which a rotating shaft is sleeved;

[0007] The bearing stator comprises a first bearing stator assembly and a second bearing stator assembly; the first bearing stator assembly applies a radial magnetic field to the rotor ring body to adjust the radial position of the rotor ring body; the second bearing stator assembly applies an axial magnetic field to the rotor ring body to adjust the axial position of the rotor ring body;

[0008] The first bearing stator assembly includes a first stator ring body, which is sleeved on the outside of the rotor ring body. The inner wall of the first stator ring body is provided with sixteen first poles evenly distributed along the circumference and extending toward the center of the rotor ring body, with a corresponding winding wound on each first pole; the sixteen first poles are divided into four pole groups in turn, each of which forms three magnetic circuits, the circulation directions of the two outer magnetic circuits being the same and opposite to the circulation direction of the middle magnetic circuit; the circulation directions of the two outer magnetic circuits in adjacent positions of adjacent pole groups are opposite;

[0009] The second bearing stator assembly includes a second stator ring body and a third stator ring body, which are respectively arranged at the axial ends of the rotor ring body and are both spaced apart from the rotor ring body; the second stator ring body and the third stator ring body are each provided with six evenly distributed second poles, and a corresponding winding is wound around each second pole; in the second stator ring body and the third stator ring body, one second pole faces two first poles alternately in the pole group, and another second pole faces the other two first poles alternately in the pole group; the magnetic circuit on the second pole has the same direction as the magnetic circuit of the first pole when passing through the first pole it faces.

[0010] Optionally, in the axial projection of the rotor ring body, the circumferential width of the two first poles in the middle position of the pole group is greater than the circumferential width of the two first poles on the outer side, and the circumferential widths of the two first poles on the outer side are the same.

[0011] Optionally, directions of winding currents on the four first poles on the pole group are set to be opposite to each other in sequence; and directions of winding currents on adjacent first poles outside adjacent pole groups are the same.

[0012] Optionally, the circumferential width of the first pole in the middle of the pole group is twice the circumferential width of the first pole at the outer side.

[0013] Optionally, the second pole is arranged on opposite end faces of the second stator ring body and the third stator ring body; the second pole is located at an outer peripheral position close to the end faces.

[0014] Optionally, third poles protruding along the inner periphery are provided on the opposite end faces of the second stator ring body and the third stator ring body. The third poles are arranged in a circular ring shape and are arranged opposite to the axial end face of the rotor ring body at a distance.

[0015] Optionally, the magnetic poles of the second poles of the second stator ring and the third stator ring are opposite in polarity.

[0016] According to another aspect of the present application, a control method for the active three-degree-of-freedom magnetic bearing as described above is provided, comprising:

[0017] Adjusting the current of at least one pole group to change the air gap magnetic flux between the first stator ring and the bearing rotor;

[0018] and / or;

[0019] The current of the winding on at least one second pole is adjusted to change the air gap magnetic flux between the bearing rotor and the second stator ring body or the third stator ring body.

[0020] According to another aspect of the present application, a motor is provided, comprising the active three-degree-of-freedom magnetic bearing as described above or the active three-degree-of-freedom magnetic bearing operated according to the control method as described above.

[0021] According to another aspect of the present application, a compressor is provided, comprising the active three-degree-of-freedom magnetic bearing as described above, the active three-degree-of-freedom magnetic bearing operated according to the control method as described above, or the motor as described above.

[0022] The present application provides an active three-degree-of-freedom magnetic bearing, comprising: a bearing rotor, comprising a rotor ring body on which a rotating shaft is sleeved;

[0023] The bearing stator comprises a first bearing stator assembly and a second bearing stator assembly; the first bearing stator assembly applies a radial magnetic field to the rotor ring body to adjust the radial position of the rotor ring body; the second bearing stator assembly applies an axial magnetic field to the rotor ring body to adjust the axial position of the rotor ring body;

[0024] The first bearing stator assembly includes a first stator ring body, which is sleeved on the outside of the rotor ring body. The inner wall of the first stator ring body is provided with sixteen first poles evenly distributed along the circumference and extending toward the center of the rotor ring body, with a corresponding winding wound on each first pole; the sixteen first poles are divided into four pole groups in turn, each of which forms three magnetic circuits, the circulation directions of the two outer magnetic circuits being the same and opposite to the circulation direction of the middle magnetic circuit; the circulation directions of the two outer magnetic circuits in adjacent positions of adjacent pole groups are opposite;

[0025] The second bearing stator assembly includes a second stator ring body and a third stator ring body, which are respectively arranged at the axial ends of the rotor ring body and are both spaced apart from the rotor ring body; the second stator ring body and the third stator ring body are each provided with six evenly distributed second poles, and a corresponding winding is wound around each second pole; in the second stator ring body and the third stator ring body, one second pole faces two first poles alternately in the pole group, and another second pole faces the other two first poles alternately in the pole group; the magnetic circuit on the second pole has the same direction as the magnetic circuit of the first pole when passing through the first pole it faces.

[0026] The present application arranges corresponding bearing stators in the radial and axial directions of the bearing rotor, with a high degree of integration, so that there is no need to assemble a thrust plate separately on the rotating shaft, the structure is more compact, the process is simplified, the bearing volume is effectively reduced, the rotating shaft length is shortened, the critical speed of the rotor is increased, and the operating stability of the magnetic levitation system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the magnetic circuit on the radial bearing stator of an embodiment of the present application;

[0028] Figure 2 This is a layout diagram of the left axial bearing stator of an embodiment of the present application;

[0029] Figure 3 This is a layout diagram of the right axial bearing stator of an embodiment of the present application;

[0030] Figure 4 For the embodiment of this application Figure 1 Middle AA view;

[0031] Figure 5 For the embodiment of this application Figure 1 Middle BB view;

[0032] Figure 6 This is a three-dimensional diagram of the axial bearing stator according to an embodiment of the present application.

[0033] The reference numerals indicate:

[0034] 1. Left axial stator; 2. Right axial stator; 3. Left axial winding; 4. Right axial winding; 5. Radial winding; a. Radial small teeth; b. Radial large teeth; c. Radial large teeth; d. Radial small teeth; 7. Bearing rotor; 8. Rotating shaft; 9. Left axial upper magnetic pole; 10. Right axial upper magnetic pole; 11. Radial stator yoke; 12. Radial stator pole; 13. Left axial lower magnetic pole; 14. Right axial lower magnetic pole; 15. Radial working gap; 16. Left axial working gap; 17. Right axial working gap; 001. Left axial magnetic circuit; 002. Right axial magnetic circuit; 003. Radial magnetic circuit. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in a sequence other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] See also Figures 1 to 6 As shown, according to an embodiment of the present application, an active three-degree-of-freedom magnetic bearing includes:

[0038] The bearing rotor 7 includes a rotor ring body on which a rotating shaft 8 is sleeved;

[0039] The bearing stator comprises a first bearing stator assembly and a second bearing stator assembly; the first bearing stator assembly applies a radial magnetic field to the rotor ring body to adjust the radial position of the rotor ring body; the second bearing stator assembly applies an axial magnetic field to the rotor ring body to adjust the axial position of the rotor ring body;

[0040] The first bearing stator assembly includes a first stator ring body, which is sleeved on the outside of the rotor ring body. The inner wall of the first stator ring body is provided with sixteen first poles evenly distributed along the circumference and extending toward the center of the rotor ring body, with a corresponding winding wound on each first pole; the sixteen first poles are divided into four pole groups in turn, each of which forms three magnetic circuits, the circulation directions of the two outer magnetic circuits being the same and opposite to the circulation direction of the middle magnetic circuit; the circulation directions of the two outer magnetic circuits in adjacent positions of adjacent pole groups are opposite;

[0041] The second bearing stator assembly includes a second stator ring body and a third stator ring body, which are respectively arranged at the axial ends of the rotor ring body and are both spaced apart from the rotor ring body; the second stator ring body and the third stator ring body are each provided with six evenly distributed second poles, and a corresponding winding is wound around each second pole; in the second stator ring body and the third stator ring body, one second pole faces two first poles alternately in the pole group, and another second pole faces the other two first poles alternately in the pole group; the magnetic circuit on the second pole has the same direction as the magnetic circuit of the first pole when passing through the first pole it faces.

[0042] The present application provides a first bearing stator assembly sleeved around the outer periphery of the bearing rotor 7, comprising a first stator ring, i.e., a radial stator yoke 11. A first pole, i.e., a radial stator pole 12, is provided on the inner wall of the radial stator yoke 11. A radial winding 5 is wound around the radial stator pole 12. The sixteen radial stator poles 12 are evenly distributed, and their combined magnetic force acts on the bearing rotor 7, resulting in a radial working gap 15 between the bearing rotor 7 and the first bearing stator assembly. The sixteen radial stator poles 12 are divided into four pole groups, each of which contains four radial stator poles 12.

[0043] In the axial direction of the bearing rotor 7, a second bearing stator assembly, namely a left axial stator 1 and a right axial stator, is arranged on the left and right sides of the first bearing stator assembly. The left axial stator 1 is provided with six left axial upward magnetic poles 9 (i.e., second poles) evenly distributed in the circumferential direction, and the left axial upward magnetic pole 9 is sleeved with a left axial winding 3. The right axial stator is provided with six right axial upward magnetic poles 10 (i.e., second poles) evenly distributed in the circumferential direction, and the right axial upward magnetic pole 10 is sleeved with a right axial winding 4. At the same time, one of the left axial upward magnetic pole 9 and the right axial upward magnetic pole 10 is facing two radial stator poles 12 arranged alternately in the pole group, and the other is facing two other radial stator poles 12 arranged alternately in the same pole group. Both the left axial stator 1 and the right axial stator 2 generate suction on the bearing rotor 7. The axial position of the bearing rotor 7 is adjusted by changing the current of the left axial winding 3 and the right axial winding 4. For example, when the bearing rotor 7 needs to be controlled to move to the left, the current of the left bearing winding is increased, and the bearing rotor 7 is subjected to a greater force to the left. Conversely, when the bearing rotor 7 needs to be controlled to move to the right, the current of the right bearing winding is increased, and the bearing rotor 7 is subjected to a greater force to the right. Therefore, by controlling the current of the left and right axial windings 4, the axial movement of the bearing rotor 7 can be controlled, and the thrust plate structure on the traditional rotating shaft 8 can be removed.

[0044] Since the magnetic circuit generated by the left-axial upward magnetic pole 9 and the right-axial upward magnetic pole 10 will partially overlap with the magnetic circuit on the radial stator pole 12, and the magnetic circuits of the left-axial upward magnetic pole 9 and the right-axial upward magnetic pole 10 both strengthen the magnetic circuit on the radial stator pole 12, the winding currents on the left-axial upward magnetic pole 9, the right-axial upward magnetic pole 10 and the radial stator pole 12 can be individually adjusted to achieve movement of the bearing rotor 7 in three degrees of freedom, effectively reducing the bearing volume and rotor length, and improving the rotor operation stability.

[0045] This application adopts sixteen-level radial bearings, which have simple processing and manufacturing processes and are convenient for controlling the radial magnetic circuit 003. There are no permanent magnets, so the cost is low, the assembly is convenient, the load-bearing capacity is large, and it can operate at high power. The magnetic poles on the axial stator adopt a pole structure to avoid the leakage of magnetic flux of the radial magnetic circuit 003 on the adjacent radial poles on the outer circle of the axial stator, and only enhance the air gap magnetic field on the radial magnetic pole. The left and right axial stators have the same structure, but are arranged at staggered angles at both ends of the radial bearing to avoid the axial magnetic circuit from being concentrated on one radial magnetic pole, thereby weakening the phenomenon that the radial magnetic pole is easily saturated. The radial and axial integration is high, there is no thrust plate, the cost is reduced, the structure is compact, the process is simple, the critical speed is high, and the performance is stable.

[0046] In some embodiments, in the axial projection of the rotor ring body, the circumferential width of the two first poles in the middle position of the pole group is greater than the circumferential width of the two first poles on the outer side, and the circumferential widths of the two first poles on the outer side are the same.

[0047] The outer radial stator poles 12 of each pole group form a closed magnetic circuit with the adjacent middle radial stator poles 12, and the closed magnetic circuit formed by the two middle radial stator poles 12 also constitutes a closed magnetic circuit, wherein the magnetic circuit circulation direction in which the outer radial stator poles 12 participate is the same and opposite to the closed magnetic circuit circulation direction formed by only the two middle radial stator poles 12; since the four radial stator poles 12 are to form three magnetic circuits, the circumferential width of the middle radial stator poles 12 is greater than that of the outer radial stator poles 12; preferably, the circumferential width of the middle radial stator poles 12 is twice that of the outer radial stator poles 12.

[0048] Each pole group constitutes a └┴┴┘-shaped structure, with its two outer magnetic poles being radial small teeth a and radial small teeth d, and the middle magnetic poles being radial large teeth b and radial large teeth c. The magnetic poles of a single └┴┴┘-shaped structure are distributed in SNSN (or NSNS) in space.

[0049] The left and right axial stators have the same structure but different installation methods. The left axial stator corresponds to the radial large teeth b and radial small teeth d of the └┴┴┘-shaped structure, which only enhances its radial air gap magnetic field; the right axial stator corresponds to the radial small teeth a and radial large teeth c of the └┴┴┘-shaped structure, which only enhances its radial air gap magnetic field. The axial magnetic flux has a positive effect on the radial magnetic flux, controlling the radial movement of the rotating shaft and realizing the movement of the rotating shaft in three degrees of freedom, radial and axial, effectively reducing the bearing volume and rotor length, and improving the rotor operation stability.

[0050] In some embodiments, the directions of the winding currents on the four first poles on the pole group are sequentially set to be opposite; and the directions of the winding currents on the adjacent first poles outside the adjacent pole groups are the same.

[0051] The limitation of the direction of the winding current on the radial stator pole 12 makes the overall structure stable, well-balanced, and easy to manufacture and control.

[0052] In some embodiments, the second pole is disposed on opposite end faces of the second stator ring and the third stator ring; the second pole is located near the outer periphery of the end faces.

[0053] Based on the magnetic circuit superposition effect between the second pole and the radial stator pole 12, the second pole is arranged on the outer peripheral edge of the opposite end face of the axial stator; at the same time, a third pole protruding along the inner peripheral edge is provided on the opposite end face, and the third pole is set in a circular ring shape and is arranged opposite to the axial end face of the rotor ring body at a distance.

[0054] The third pole is the downward magnetic pole of the axial stator, such as the left axial downward magnetic pole 13 on the left axial stator 1 and the right axial downward magnetic pole 14 on the right axial stator, which are arranged opposite to the bearing rotor 7, forming a left axial working gap 16 and a right axial working gap 17 on both sides respectively.

[0055] In some embodiments, the magnetic poles of the second poles of the second stator ring and the third stator ring are opposite in polarity.

[0056] The current directions of the left axial winding 3 and the right axial winding 4 are the same, as shown in Figure 4 and 5 As shown, magnetic flux in the same direction is provided to the radial stator, thereby forming a suction force on the bearing rotor 7 respectively.

[0057] According to another aspect of the present application, a control method for the active three-degree-of-freedom magnetic bearing as described above is provided, comprising:

[0058] Adjust the current of at least one pole group to change the air gap magnetic flux between the first stator ring and the bearing rotor 7;

[0059] and / or;

[0060] The current of the winding on at least one second pole is adjusted to change the air gap magnetic flux between the bearing rotor 7 and the second stator ring body or the third stator ring body.

[0061] The present application is an active three-degree-of-freedom magnetic bearing structure, the magnetic circuit is as follows Figure 1 As shown, the upper magnetic pole of the axial stator is located inside the radial winding 5 and is connected to the radial stator pole 12. The lower magnetic pole of the axial stator is located at both axial ends of the bearing rotor 7. The axial magnetic circuit generated by the axial winding includes a left axial magnetic circuit 001 and a right axial magnetic circuit 002, which are used to control the axial movement of the bearing rotor 7. The left axial magnetic circuit 001 is shown in FIG. Figure 4 As shown, the left axial stator lower magnetic pole 13 - left axial working gap 16 - bearing rotor 7 - radial working gap 15 - radial stator pole 12 - left axial upper magnetic pole 9 returns to the left axial stator 1 and closes. The right axial magnetic circuit 002 is as shown Figure 5 As shown, the system passes through the right axial upper magnetic pole 10 - radial stator pole 12 - radial working gap 15 - bearing rotor 7 - right axial working gap 17 - right axial stator lower magnetic pole 14 and returns to the right axial stator 2 to close. When the bearing rotor 7 needs to be controlled to move to the left, the current of the left bearing winding is increased, and the bearing rotor 7 is subjected to a greater suction force to the left. Conversely, when the bearing rotor 7 needs to be controlled to move to the right, the current of the right bearing winding is increased, and the bearing rotor 7 is subjected to a greater suction force to the right. Therefore, the axial movement of the bearing rotor 7 is controlled by controlling the magnitude of the left and right axial winding currents.

[0062] Two bearing stator structures in the axial direction, such as Figure 6 As shown, the magnetic poles on the axial stator adopt a pole structure, which is divided into six axial poles. Six axial coils are wound on the axial poles respectively. The left and right axial stators have the same structure but different installation methods. Figure 2 and 3As shown, the left axial stator 1 corresponds to the radial large teeth b and radial small teeth d of the └┴┴┘-shaped structure during assembly, and the left axial magnetic circuit 001 is as follows Figure 4 As shown by the dotted lines, all of them point to the circumference (or all point to the center of the circle), and only the radial large teeth b and radial small teeth d of the └┴┴┘-shaped structure are enhanced. When the right axial stator is assembled, the radial small teeth a and radial large teeth c of the └┴┴┘-shaped structure are corresponding. The right axial magnetic circuit 002 is as follows Figure 5 As shown by the dotted lines, all points are directed toward the center of the circle (or all toward the circumference), only the radial air gap magnetic field of the radial small tooth a and the radial large tooth c is enhanced, and the axial magnetic flux has a positive effect on the radial magnetic flux. It does not reduce the radial magnetic circuit, and it will enhance the radial air gap magnetic flux in one quadrant. However, this only affects the effect of the axial magnetic flux on the pole in one quadrant. In the four quadrants, the enhancement of the radial magnetic flux by the axial magnetic flux cancels each other out. That is, although the radial and axial magnetic circuits of the integrated magnetic bearing both flow through the bearing rotor 7, even if the axial magnetic circuit changes, it will not affect the overall radial magnetic circuit. As a result, the axial and radial magnetic circuits each play their respective roles, simplifying the control of the magnetic bearing.

[0063] The installation methods of the left and right axial stators can be swapped. The left axial stator 1 corresponds to the radial small teeth a and radial large teeth c of the └┴┴┘-shaped structure, and only enhances the air gap magnetic field of the radial small teeth a and radial large teeth c of the └┴┴┘-shaped structure; the right axial stator corresponds to the radial large teeth b and radial small teeth d of the └┴┴┘-shaped structure, and only enhances the air gap magnetic field of the radial large teeth b and radial small teeth d of the └┴┴┘-shaped structure.

[0064] When the bearing rotor 7 needs to be controlled to move to the upper left, the upper left radial bearing is energized to provide a radial force to the upper left. When the bearing rotor 7 needs to be controlled to move upward, the upper left and right radial bearings are energized to provide an upward radial force to the bearing rotor 7. This control method is simple and can control the radial movement of the rotating shaft 8 in a wide range of directions. This three-degree-of-freedom magnetic bearing integrates the radial bearing with the axial bearing, shortening the rotor length and increasing the rotor's critical speed. The axial bearing's magnetic poles are segmented to prevent magnetic leakage from the radial magnetic circuit 003 on the outer circle of the axial stator, enhancing the air gap magnetic field on the radial magnetic poles and achieving stable radial suspension.

[0065] According to another aspect of the present application, a motor is provided, comprising the active three-degree-of-freedom magnetic bearing as described above or the active three-degree-of-freedom magnetic bearing operated according to the control method as described above.

[0066] According to another aspect of the present application, a compressor is provided, comprising the active three-degree-of-freedom magnetic bearing as described above, the active three-degree-of-freedom magnetic bearing operated according to the control method as described above, or the motor as described above.

[0067] It is easy for those skilled in the art to understand that the above embodiments can be freely combined and superimposed without conflict.

[0068] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. The above description is merely a preferred embodiment of the present application. It should be noted that those skilled in the art can make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.

Claims

1. An active three-degree-of-freedom magnetic bearing, characterized in that: include: A bearing rotor (7) includes a rotor ring body on which a rotating shaft (8) is sleeved; The bearing stator comprises a first bearing stator assembly and a second bearing stator assembly; the first bearing stator assembly applies a radial magnetic field to the rotor ring body to adjust the radial position of the rotor ring body; the second bearing stator assembly applies an axial magnetic field to the rotor ring body to adjust the axial position of the rotor ring body; The first bearing stator assembly includes a first stator ring body, which is sleeved on the outside of the rotor ring body. The inner wall of the first stator ring body is provided with sixteen first poles evenly distributed along the circumference and extending toward the center of the rotor ring body, and a corresponding winding is wound around each first pole. The sixteen first poles are divided into four pole groups in turn, and each first pole group forms three magnetic circuits. The circulation directions of the two outer magnetic circuits are the same and opposite to the circulation direction of the middle magnetic circuit. The circulation directions of the two outer magnetic circuits in adjacent positions of adjacent pole groups are opposite. The second bearing stator assembly includes a second stator ring body and a third stator ring body, which are respectively arranged at the axial ends of the rotor ring body and are both spaced apart from the rotor ring body; the second stator ring body and the third stator ring body are each provided with six evenly distributed second poles, and a corresponding winding is wound around each second pole; in the second stator ring body and the third stator ring body, one second pole faces two first poles alternately in the pole group, and another second pole faces the other two first poles alternately in the pole group; the magnetic circuit on the second pole has the same direction as the magnetic circuit of the first pole when passing through the first pole it faces.

2. The active three-degree-of-freedom magnetic bearing according to claim 1, characterized in that: In the axial projection of the rotor ring body, the circumferential widths of the two first poles at the middle position of the pole group are greater than the circumferential widths of the two first poles at the outer sides, and the circumferential widths of the two first poles at the outer sides are the same.

3. The active three-degree-of-freedom magnetic bearing according to claim 2, characterized in that: The directions of the winding currents on the four first poles on the pole group are sequentially set to be opposite; and the directions of the winding currents on the adjacent first poles outside the adjacent pole groups are the same.

4. The active three-degree-of-freedom magnetic bearing according to any one of claims 1 to 3, characterized in that: The circumferential width of the first pole at the middle position of the pole group is twice the circumferential width of the first pole at the outer position.

5. The active three-degree-of-freedom magnetic bearing according to claim 4, characterized in that: The second pole is arranged on the opposite end faces of the second stator ring body and the third stator ring body; the second pole is located near the outer peripheral edge of the end faces.

6. The active three-degree-of-freedom magnetic bearing according to claim 5, characterized in that: The second stator ring body and the third stator ring body are both provided with third poles protruding along the inner periphery on the opposite end faces thereof. The third poles are provided in an annular shape and are arranged opposite to the axial end face of the rotor ring body at a distance.

7. The active three-degree-of-freedom magnetic bearing according to claim 6, characterized in that: The magnetic poles of the second poles of the second stator ring and the third stator ring are opposite in polarity.

8. A control method for an active three-degree-of-freedom magnetic bearing according to any one of claims 1 to 7, characterized in that: include: Adjusting the current of at least one pole group to change the air gap magnetic flux between the first stator ring and the bearing rotor (7); and / or; The magnitude of the current of the winding on at least one second pole is adjusted to change the magnitude of the air gap magnetic flux between the bearing rotor (7) and the second stator ring body or the third stator ring body.

9. A motor, characterized in that: It comprises the active three-degree-of-freedom magnetic bearing according to any one of claims 1 to 7 or the active three-degree-of-freedom magnetic bearing operated according to the control method according to claim 8.

10. A compressor, characterized in that: It comprises the active three-degree-of-freedom magnetic bearing according to any one of claims 1 to 7, the active three-degree-of-freedom magnetic bearing operated according to the control method according to claim 8, or the motor according to claim 9.

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