Five-degree-of-freedom hybrid magnetic bearing, motor and control method thereof

Abstract

The application provides a five-degree-of-freedom hybrid magnetic suspension bearing, a motor and a control method thereof. The magnetic suspension bearing comprises an axial stator core, front and rear radial stator cores, first and second permanent magnet rings respectively arranged between the radial stator cores and the end portions of the axial stator core, the axial stator core comprises an axial stator yoke portion and first and second axial stator rings arranged on the axial stator yoke portion and extending in the radial direction of the axial stator yoke portion, the first and second axial stator rings are opposite to each other and a first annular space is formed between the first and second axial stator rings, the edge region of a rotating shaft thrust disc is located in the first annular space, and only a group of axial control coils is arranged in the first annular space. The application can realize adjustment and control of the axial position of the rotating shaft thrust disc by controlling only the group of axial control coils, the control logic is simpler, the length of the corresponding rotating shaft can be shortened, and the rotating speed of the rotating shaft is improved.

Description

Five-degree-of-freedom hybrid magnetic levitation bearing, motor and its control method Technical Field

[0001] This invention belongs to the field of magnetic levitation bearing design technology, specifically relating to a five-degree-of-freedom hybrid magnetic levitation bearing, a motor, and a control method thereof. Background Technology

[0002] The bias magnetic field of a permanent magnet biased magnetic levitation bearing is established by a permanent magnet, while the control magnetic field is established by an electromagnet (electromagnetic coil). Compared with traditional electromagnetic biased magnetic levitation bearings, it has significant advantages such as lower energy consumption, smaller size, and lighter weight. Because the permanent magnet has more flexibility in the choice of shape and placement than the electromagnet, the topological structure of the permanent magnet biased magnetic levitation bearing is more diverse than that of the electromagnetic biased type.

[0003] Based on the different methods of providing magnetic force, magnetic levitation bearings are classified into: active magnetic levitation bearings, passive magnetic levitation bearings, and hybrid magnetic levitation bearings. Active magnetic bearings use electromagnetic coils on the stator to generate electromagnetic force, suspending the rotor stably in space. Passive magnetic bearings are magnetic levitation bearings using permanent magnets. Hybrid magnetic levitation bearings utilize the magnetic field generated by permanent magnets, replacing the static bias magnetic field generated by electromagnets in active magnetic levitation bearings. This significantly reduces power loss, decreases the ampere-turns of the electromagnets, reduces the size of the magnetic levitation bearing, and improves its efficiency.

[0004] The applicant previously proposed a low-power permanent magnet biased five-degree-of-freedom integrated magnetic bearing (publication number CN10615331A). Specifically, a magnetic shielding aluminum ring is provided between the left axial magnetic bearing core and the right axial magnetic bearing core. The left radial magnetic bearing control coil and the right radial magnetic bearing control coil are wound in the stator slots of the left radial magnetic bearing core and the right radial magnetic bearing core, respectively. The left axial magnetic bearing core and the right axial magnetic bearing core are both E-shaped structures, and control coils are wound in the stator slots, respectively. This invention effectively solves the shortcomings of existing five-degree-of-freedom magnetic levitation systems, providing a low-power permanent magnet biased five-degree-of-freedom integrated magnetic bearing that is small in size, light in weight, short in axial length, high in critical speed, high in core utilization, simple in structure, manufacturing and assembly, and whose axial and radial control magnetic fluxes do not pass through permanent magnets, and can generate greater axial and radial levitation forces. However, because its axial control coils are set in two sets, one on the left and one on the right, respectively, and the two sides of the axial magnetic bearing core also have two sets of radial magnetic bearing cores, the axial length of the five-degree-of-freedom magnetic bearing is too large, resulting in a correspondingly large shaft length in the shaft system in which it is used, which limits the speed increase and makes the control more complex. The opposing structure of the two sets of axial control coils also requires the use of magnetic isolation rings to isolate the magnetic circuits of the two axial cores to reduce magnetic leakage, which makes the structure of the magnetic bearing relatively complex. Summary of the Invention

[0005] Therefore, the present invention provides a five-degree-of-freedom hybrid magnetic levitation bearing, a motor and a control method thereof, which can solve the technical problems in the prior art where the five-degree-of-freedom hybrid magnetic levitation bearing uses two sets of axial control coils that are arranged in opposite directions, resulting in an excessively large axial length of the magnetic bearing, which limits the corresponding increase in the rotational speed, and the control is relatively complex and the bearing structure design is relatively complicated.

[0006] To address the aforementioned problems, this invention provides a five-degree-of-freedom hybrid magnetic levitation bearing, comprising an axial stator core and a front radial stator core and a rear radial stator core located at opposite ends of the axial stator core. A first permanent magnet ring is disposed between the ends of the front radial stator core and the axial stator core, and a second permanent magnet ring is disposed between the ends of the rear radial stator core and the axial stator core. The opposite ends of the first and second permanent magnet rings have the same polarity. The axial stator core includes an axial stator yoke and a first and a second axial stator ring located on the axial stator yoke and extending radially therefrom. The first and second axial stator rings are opposite each other and form a first annular gap between them. The edge region of the shaft thrust disk is accommodated within the first annular gap. Only one set of axial control coils is disposed within the first annular gap, and the axial control coils are arranged around the shaft thrust disk.

[0007] In some embodiments, the first axial stator ring has a first axially extending tooth that extends along the axial direction of the axial stator core and close to the shaft thrust disk, and the second axial stator ring has a second axially extending tooth that extends along the axial direction of the axial stator core and close to the shaft thrust disk, with the edge region of the shaft thrust disk located between the first axially extending tooth and the second axially extending tooth.

[0008] In some embodiments, the axial stator yoke is a yoke ring structure, with the first axial stator ring and the second axial stator ring connected to the inner ring wall of the yoke ring structure, and the axial control coil wound and assembled on the inner ring wall and located radially outside the shaft thrust disk.

[0009] In some embodiments, the axial stator yoke is a yoke ring structure, with the first axial stator ring and the second axial stator ring connected to the inner ring wall of the yoke ring structure. The inner ring wall has a receiving ring groove, and the axial control coil is wound and assembled in the receiving ring groove and located on the radially outer side of the rotating shaft thrust disk.

[0010] In some embodiments, the axial stator yoke is a shaft structure, the first axial stator ring and the second axial stator ring are connected to the outer peripheral wall of the shaft structure, and the axial control coil is wound and assembled on the outer peripheral wall and is located radially inside the rotating shaft thrust disk.

[0011] In some embodiments, the axial control coil is radially symmetrical about the first annular interval; and / or, the axial stator core is formed by assembling two mutually symmetrical core sub-body pieces.

[0012] The present invention also provides an electric motor, including a shaft, said shaft being supported on at least one of the above-described five-degree-of-freedom hybrid magnetic levitation bearings.

[0013] The present invention also provides a control method for a motor as described above, comprising the following steps:

[0014] The first minimum distance da between the rotating shaft thrust disk and the first axial stator ring and the second minimum distance db between the rotating shaft thrust disk and the second axial stator ring are obtained respectively.

[0015] Based on the relationship between da and db, the direction and / or magnitude of the current in the axial control coil are adjusted so that the rotating shaft thrust plate moves axially toward the side with the larger value between da and db.

[0016] In some embodiments, adjusting the current direction and / or current magnitude in the axial control coil according to the relationship between da and db, so that the rotating shaft thrust disk moves axially toward the side with the larger value of da and db, specifically includes:

[0017] When da > db, the current direction in the axial control coil is controlled to be a first direction so that the control magnetic circuit generated by the axial control coil is superimposed in the same direction as the permanent magnet bias magnetic circuit generated by the first permanent magnet ring, and is reduced in the opposite direction to the permanent magnet bias magnetic circuit generated by the second permanent magnet ring, thereby controlling the magnitude of the current in the axial control coil to become smaller and smaller; or...

[0018] When da < db, the current direction in the axial control coil is controlled to be the second direction so that the control magnetic circuit generated by the axial control coil is reduced in the opposite direction to the permanent magnet bias magnetic circuit generated by the first permanent magnet ring and superimposed in the same direction with the permanent magnet bias magnetic circuit generated by the second permanent magnet ring, thereby controlling the current in the axial control coil to become smaller and smaller, and the first direction is opposite to the second direction.

[0019] In some embodiments, adjusting the current direction and / or current magnitude in the axial control coil according to the relationship between da and db, so that the rotating shaft thrust disk moves axially toward the side with the larger value of da and db, specifically includes:

[0020] When da = db, the direction and / or magnitude of the current in the axial control coil remain unchanged.

[0021] This invention provides a five-degree-of-freedom hybrid magnetic levitation bearing, motor, and control method thereof. By setting only one set of axial control coils coaxially with the shaft thrust plate in the first annular interval, the magnetic flux can be canceled or superimposed by utilizing the directional differences between the permanent magnet bias magnetic circuit and the axial control magnetic circuit. This allows for the adjustment and control of the axial position of the shaft thrust plate by controlling only one set of axial control coils, simplifying the control logic. Furthermore, since only one set of axial control coils is used, there is a smaller axial space requirement, allowing for a smaller shaft length of the five-degree-of-freedom magnetic bearing, thus shortening the corresponding shaft length and increasing the shaft speed. More importantly, the first permanent magnet ring and the second permanent magnet ring are respectively positioned between the axial stator core and the two radial stator cores, isolating the axial and radial control magnetic circuits. This effectively reduces the coupling between the radial and axial control magnetic circuits, further reducing the control difficulty of the magnetic bearing, thus simplifying the control logic. Attached Figure Description

[0022] Figure 1 is a schematic diagram of the axial section of a five-degree-of-freedom hybrid magnetic levitation bearing in one embodiment of the present invention (only half of the axial section is shown), and the arrows in the figure indicate the direction of the magnetic circuit.

[0023] Figure 2 is a schematic diagram of the axial section of a five-degree-of-freedom hybrid magnetic levitation bearing in another embodiment of the present invention (only half of the axial section is shown), and the arrows in the figure indicate the direction of the magnetic circuit;

[0024] Figure 3 is a schematic diagram of the axial section of a five-degree-of-freedom hybrid magnetic levitation bearing in another embodiment of the present invention (only half of the axial section is shown), and the arrows in the figure indicate the direction of the magnetic circuit;

[0025] Figure 4 is a schematic diagram of the axial projection of Figure 1, and the arrows in the figure indicate the radial magnetic circuit direction;

[0026] Figure 5 is a schematic diagram of the axial section of a five-degree-of-freedom hybrid magnetic levitation bearing in another embodiment of the present invention. The arrows in the figure indicate the direction of the magnetic circuit.

[0027] The reference numerals in the attached figures are as follows:

[0028] 1. Axial stator core; 11. Axial stator yoke; 12. First axial stator ring; 13. Second axial stator ring; 14. Axial control coil; 15. First axial extension tooth; 16. Second axial extension tooth; 21. Front radial stator core; 22. Rear radial stator core; 23. Radial stator yoke; 24. Radial stator tooth; 25. Radial control coil; 31. First permanent magnet ring; 32. Second permanent magnet ring; 100. Rotating shaft thrust plate; 101. Rotating shaft; 201. Axial control magnetic circuit; 202. Front radial control magnetic circuit; 203. Rear radial control magnetic circuit; 204. First permanent magnet bias magnetic circuit; 205. Second permanent magnet bias magnetic circuit. Detailed Implementation

[0029] Referring to Figures 1 and 5, according to an embodiment of the present invention, a five-degree-of-freedom hybrid magnetic levitation bearing is provided, comprising an axial stator core 1 and a front radial stator core 21 and a rear radial stator core 22 respectively located at the axial ends of the axial stator core 1. A first permanent magnet ring 31 is disposed between the end of the front radial stator core 21 and the end of the axial stator core 1, and a second permanent magnet ring 32 is disposed between the end of the rear radial stator core 22 and the end of the axial stator core 1. The opposite ends of the first permanent magnet ring 31 and the second permanent magnet ring 32 have the same polarity (e.g., both are S poles). The axial stator core 1 includes an axial... The stator yoke 11 and the first axial stator ring 12 and the second axial stator ring 13 located on the axial stator yoke 11 and extending radially therein, the first axial stator ring 12 and the second axial stator ring 13 are opposite each other and form a first annular gap between them, the edge region of the rotating shaft thrust disk 100 (also referred to as the rotor core) is accommodated in the first annular gap, so that the first axial stator ring 12 and the second axial stator ring 13 have output regions opposite to the rotating shaft thrust disk 100, and only one set of axial control coils 14 is provided in the first annular gap, the axial control coils 14 are arranged around the rotating shaft thrust disk 100.

[0030] In this technical solution, by setting only one set of axial control coils 14 coaxially with the rotating shaft thrust disk 100 in the first annular interval, the magnetic flux can be canceled or superimposed by utilizing the difference in direction between the permanent magnet bias magnetic circuit and the axial control magnetic circuit. Thus, by controlling only one set of axial control coils 14, the axial position of the rotating shaft thrust disk 100 can be adjusted and controlled. The control logic is simpler, and since only one set of axial control coils is set, there is a smaller axial space requirement. The shaft length of the five-degree-of-freedom magnetic bearing can be designed to be smaller, thereby shortening the corresponding shaft length and increasing the shaft speed. More importantly, the first permanent magnet ring 31 and the second permanent magnet ring 32 are respectively located between the axial stator core and the two radial stator cores, which can isolate the axial control magnetic circuit and the radial control magnetic circuit, effectively reducing the coupling between the radial control magnetic circuit and the axial control magnetic circuit, further reducing the control difficulty of the magnetic bearing, that is, the control logic is simplified.

[0031] The first annular interval is symmetrical about its radial symmetry plane. Taking the orientation shown in Figure 1 as an example, that is, the first annular interval is symmetrical about the radial symmetry plane, which is perpendicular to the central axis of the magnetic levitation bearing. In a preferred embodiment, the axial control coil 14 is symmetrical about the aforementioned radial symmetry plane of the first annular interval. This ensures that the axial control magnetic circuit generated by the axial control coil 14 after being energized is symmetrical about the radial symmetry plane. Furthermore, the aforementioned first permanent magnet ring 31 and second permanent magnet ring 32 are also symmetrical about the radial symmetry plane. In this way, the permanent magnet bias magnetic circuit of the rotating shaft thrust disk 100 is symmetrical about the left and right, further reducing the control difficulty of the magnetic bearing and simplifying the control logic.

[0032] Specifically, taking the five-degree-of-freedom hybrid magnetic levitation bearing shown in Figure 2 as an example, the first permanent magnet ring 31 and the second permanent magnet ring 32 are completely identical in magnetic properties, generating the first permanent magnet bias magnetic circuit 204 and the second permanent magnet bias magnetic circuit 205 respectively. Since they are structurally symmetrical about the aforementioned radial symmetry plane, they have balanced axial force output. The axial displacement of the shaft 101 is completely controlled by adjusting the magnitude and direction of the current in the axial control coil 14, making control very simple. In addition, the first permanent magnet ring 31 and the second permanent magnet ring 32, while providing symmetrical bias magnetic circuits respectively, also effectively prevent the flow of the axial control magnetic circuit 201 to the forward radial control magnetic circuit 202 and the rear radial control magnetic circuit 203 side, thereby preventing the coupling between the two. Figure 4 shows an axial projection view of the five-degree-of-freedom hybrid magnetic levitation bearing. It can be seen that in this embodiment, both the front radial stator core 21 and the rear radial stator core 22 include a radial stator yoke 23 (specifically a yoke ring) and several radial stator teeth 24 spaced apart along the circumference of the shaft 101. Each radial stator tooth 24 is wound with a radial control coil 25, which is used to generate radial control magnetic circuits (e.g., front radial control magnetic circuit 202 and rear radial control magnetic circuit 203). Furthermore, it is clear that in this invention, the permanent magnet bias magnetic circuit is single (compared to structures such as the E-type axial stator core) without branches, resulting in less magnetic leakage. The axial control magnetic circuit is directly formed by the axial stator core 1 and the shaft thrust disk 100, resulting in high material and space utilization.

[0033] In a specific embodiment, referring to Figures 1, 3, and 5, the first axial stator ring 12 has a first axially extending tooth 15 extending along the axial direction of the axial stator core 1 towards the rotating shaft thrust disk 100, and the second axial stator ring 13 has a second axially extending tooth 16 extending along the axial direction of the axial stator core 1 towards the rotating shaft thrust disk 100. At this time, the edge region of the rotating shaft thrust disk 100 is located between the first axially extending tooth 15 and the second axially extending tooth 16. Unlike the embodiment shown in Figure 1, the two axial stator rings in this embodiment are respectively provided with axially extending teeth. In this way, the volume of the first annular gap that can be used to accommodate the axial control coil 14 can be designed to be relatively large. This is beneficial for the axial control coil 14 to have a good heat dissipation effect, thereby improving the reliability of the magnetic bearing. At the same time, it can also ensure that the axial air gap between the axial stator core 1 and the rotating shaft thrust disk 100 is within a reasonable range, preventing magnetic leakage. Referring further to the embodiment shown in Figure 1, the first axial stator ring 12 and the second axial stator ring 13 do not have the aforementioned first axial extension tooth 15 and second axial extension tooth 16. This method can further reduce the axial length of the magnetic bearing and reduce the overall volume of the bearing.

[0034] Referring to Figures 1 to 3, the axial stator yoke 11 is a yoke ring structure. The first axial stator ring 12 and the second axial stator ring 13 are connected to the inner ring wall of the yoke ring structure, thereby forming the magnetic levitation bearing as an inner rotor magnetic bearing. The first axial stator ring 12 and the second axial stator ring 13 are spaced apart along the axial direction of the yoke ring structure, and the spaced-out points form the aforementioned first annular gap. The axial control coil 14 is wound and assembled on the inner ring wall and is located on the radially outer side of the shaft thrust disk 100, as shown in Figure 1 or Figure 2. The axial control coil 14 can be assembled and connected (e.g., by adhesive connection or interference fit) to the inner ring wall using a corresponding insulating frame (or other assembly structure). The axial control coil 14 is entirely located within the yoke ring structure. The outer region will not damage the yoke structure, the magnetic circuit area will not decrease, and the magnetic reluctance will be relatively small, thus not adversely affecting the flow direction of the axial control magnetic circuit 201, which is beneficial for the effective control of the magnetic levitation bearing. Referring to Figure 3, which differs from the structures shown in Figures 1 and 2, in this embodiment, the aforementioned inner ring wall has a receiving annular groove (not labeled in the figure). The axial control coil 14 is wound and assembled within the receiving annular groove and is located radially outside the rotating shaft thrust disk 100. In this technical solution, the axial control coil 14 is assembled through the receiving annular groove, simplifying the connection structure and making the coil assembly more reliable. This method, as a feasible approach, reduces the magnetic circuit area to a certain extent and increases the magnetic reluctance because a receiving groove is formed on the stator core. In this embodiment, the radially outer edge region of the rotating shaft thrust disk 100 is located within the aforementioned first annular gap.

[0035] Referring to Figure 5, the axial stator yoke 11 is a shaft structure. The first axial stator ring 12 and the second axial stator ring 13 are connected to the outer peripheral wall of the shaft structure, thereby forming the magnetic levitation bearing as an external rotor magnetic bearing. The first axial stator ring 12 and the second axial stator ring 13 are spaced apart along the axial direction of the shaft structure, forming the aforementioned first annular gap. The axial control coil 14 is wound and assembled on the outer peripheral wall and is located radially inside the shaft thrust disk 100, thus enriching the application scenarios of the magnetic levitation bearing in this invention. In this embodiment, the radially inner edge region of the shaft thrust disk 100 is located within the aforementioned first annular gap.

[0036] In a preferred embodiment, the axial stator core 1 is assembled from two mutually symmetrical core sub-body (not labeled in the figure), and the two symmetrical core sub-body facilitates the maintenance of the axial control coil 14.

[0037] According to an embodiment of the present invention, an electric motor is also provided, including a shaft 101, which is supported on at least one of the aforementioned five-degree-of-freedom hybrid magnetic levitation bearings.

[0038] According to an embodiment of the present invention, a control method for a motor as described above is also provided, comprising the following steps: obtaining, by means of a displacement sensor, a first minimum distance da between the shaft thrust disk 100 and the first axial stator ring 12 and a second minimum distance db between the shaft thrust disk 100 and the second axial stator ring 13, that is, the axial width of the air gap between the two end faces of the shaft thrust disk 100 and the first axial stator ring 12 and the second axial stator ring 13, respectively; adjusting the current direction and / or current magnitude in the axial control coil 14 according to the relationship between da and db so that the shaft thrust disk 100 moves axially toward the side with the larger value of da and db.

[0039] In this technical solution, when the rotating shaft thrust disk 100 is not centered, its axial position can be adjusted simply by controlling the direction and magnitude of the current in a set of axial control coils 14, which greatly simplifies the adjustment control logic of the axial displacement of the magnetic levitation bearing.

[0040] In some embodiments, adjusting the current direction and / or magnitude within the axial control coil 14 according to the relationship between da and db to make the rotating shaft thrust disk 100 move axially toward the side with the larger value of da and db specifically includes: when da > db, controlling the current direction within the axial control coil 14 to be a first direction so that the control magnetic circuit generated by the axial control coil 14 is superimposed in the same direction as the permanent magnet bias magnetic circuit generated by the first permanent magnet ring 31, and is reduced in the opposite direction to the permanent magnet bias magnetic circuit generated by the second permanent magnet ring 32, thus controlling the current magnitude within the axial control coil 14 to become smaller and smaller; or, when da < db, controlling the current direction within the axial control coil 14 to be a second direction so that the control magnetic circuit generated by the axial control coil 14 is reduced in the opposite direction to the permanent magnet bias magnetic circuit generated by the first permanent magnet ring 31, and is superimposed in the same direction to the permanent magnet bias magnetic circuit generated by the second permanent magnet ring 32, thus controlling the current magnitude within the axial control coil 14 to become smaller and smaller, with the first direction being opposite to the second direction. When da = db, simply maintaining the current direction and / or magnitude within the axial control coil 14 unchanged is sufficient.

[0041] The radial position of the rotating shaft 101 can be adjusted according to the radial bearing adjustment method in the prior art. Since its adjustment is decoupled from the axial control magnetic circuit, it can be adjusted independently, which will not be elaborated here.

[0042] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0043] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above are merely preferred embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A five-degree-of-freedom hybrid magnetic levitation bearing, characterized in that, The axial stator core includes an axial stator core (1) and a front radial stator core (21) and a rear radial stator core (22) located at opposite ends of the axial stator core (1). A first permanent magnet ring (31) is provided between the front radial stator core (21) and the end of the axial stator core (1), and a second permanent magnet ring (32) is provided between the rear radial stator core (22) and the end of the axial stator core (1). The opposite ends of the first permanent magnet ring (31) and the second permanent magnet ring (32) are of the same polarity. (1) Includes an axial stator yoke (11) and a first axial stator ring (12) and a second axial stator ring (13) located on the axial stator yoke (11) and extending radially thereon. The first axial stator ring (12) and the second axial stator ring (13) are opposite each other and form a first annular gap between them. The edge region of the rotating shaft thrust disk (100) is accommodated in the first annular gap. Only one set of axial control coils (14) is provided in the first annular gap. The axial control coils (14) are arranged around the rotating shaft thrust disk (100).

2. The five-degree-of-freedom hybrid magnetic levitation bearing according to claim 1, characterized in that, The first axial stator ring (12) has a first axially extending tooth (15) extending along the axial direction of the axial stator core (1) and close to the rotating shaft thrust disk (100), and the second axial stator ring (13) has a second axially extending tooth (16) extending along the axial direction of the axial stator core (1) and close to the rotating shaft thrust disk (100), and the edge region of the rotating shaft thrust disk (100) is located between the first axially extending tooth (15) and the second axially extending tooth (16).

3. The five-degree-of-freedom hybrid magnetic levitation bearing according to claim 1 or 2, characterized in that, The axial stator yoke (11) is a yoke ring structure. The first axial stator ring (12) and the second axial stator ring (13) are connected to the inner ring wall of the yoke ring structure. The axial control coil (14) is wound and assembled on the inner ring wall and is located on the radial outer side of the rotating shaft thrust disk (100).

4. The five-degree-of-freedom hybrid magnetic levitation bearing according to claim 1 or 2, characterized in that, The axial stator yoke (11) is a yoke ring structure. The first axial stator ring (12) and the second axial stator ring (13) are connected to the inner ring wall of the yoke ring structure. The inner ring wall has a receiving ring groove. The axial control coil (14) is wound and assembled in the receiving ring groove and is located on the radial outside of the rotating shaft thrust disk (100).

5. The five-degree-of-freedom hybrid magnetic levitation bearing according to claim 1 or 2, characterized in that, The axial stator yoke (11) is a shaft structure. The first axial stator ring (12) and the second axial stator ring (13) are connected to the outer peripheral wall of the shaft structure. The axial control coil (14) is wound and assembled on the outer peripheral wall and is located on the radial inner side of the rotating shaft thrust disk (100).

6. The five-degree-of-freedom hybrid magnetic levitation bearing according to claim 1, characterized in that, The axial control coil (14) is radially symmetrical about the first annular interval; and / or, the axial stator core (1) is formed by assembling two mutually symmetrical core sub-body.

7. An electric motor, comprising a rotating shaft (101), characterized in that, The shaft (101) is supported at least on a five-degree-of-freedom hybrid magnetic levitation bearing as described in any one of claims 1 to 6.

8. A method for controlling a motor as described in claim 7, characterized in that, The process includes the following steps: obtaining the first minimum distance da between the rotating shaft thrust disk (100) and the first axial stator ring (12) and the second minimum distance db between the rotating shaft thrust disk (100) and the second axial stator ring (13); and adjusting the current direction and / or current magnitude in the axial control coil (14) according to the relationship between da and db so that the rotating shaft thrust disk (100) moves axially toward the side with the larger value between da and db.

9. The control method according to claim 8, characterized in that, Based on the relationship between da and db, adjusting the current direction and / or current magnitude in the axial control coil (14) to make the rotating shaft thrust disk (100) move axially toward the side with the larger value of da and db specifically includes: when da > db, controlling the current direction in the axial control coil (14) to be a first flow direction so that the control magnetic circuit generated by the axial control coil (14) is superimposed in the same direction as the permanent magnet bias magnetic circuit generated by the first permanent magnet ring (31), and superimposed with the permanent magnet generated by the second permanent magnet ring (32). The bias magnetic circuit is reduced in the opposite direction, and the current in the axial control coil (14) is reduced. Alternatively, when da < db, the current direction in the axial control coil (14) is controlled to be the second direction so that the control magnetic circuit generated by the axial control coil (14) is reduced in the opposite direction to the permanent magnet bias magnetic circuit generated by the first permanent magnet ring (31) and superimposed in the same direction with the permanent magnet bias magnetic circuit generated by the second permanent magnet ring (32), and the current in the axial control coil (14) is reduced. The first direction is opposite to the second direction.

10. The control method according to claim 8, characterized in that, Adjusting the current direction and / or current magnitude in the axial control coil (14) according to the relationship between da and db so that the rotating shaft thrust disk (100) moves axially toward the side with the larger value of da and db specifically includes: when da=db, maintaining the current direction and / or current magnitude in the axial control coil (14) unchanged.

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