CN108547867B

CN108547867B - Axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing

Info

Publication number: CN108547867B
Application number: CN201810217806.4A
Authority: CN
Inventors: 张维煜; 程玲
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2018-03-16
Filing date: 2018-03-16
Publication date: 2020-09-25
Anticipated expiration: 2038-03-16
Also published as: CN108547867A

Abstract

The invention discloses a three-degree-of-freedom spherical hybrid magnetic bearing with an axial self-loop, wherein an upper axial stator, an upper annular permanent magnet, a radial stator, a lower annular permanent magnet and a lower axial stator are sequentially and coaxially sleeved outside a rotor from top to bottom, the upper axial stator and the lower axial stator are respectively formed by axially connecting an upper disc, a middle disc and a receiving disc, the inner end surface of each upper disc radially and inwards extends a conical disc, small discs are arranged between the upper end surface and the lower end surface of the rotor and the corresponding conical discs, the small discs are tightly attached to the upper surface and the lower surface of the corresponding conical discs, the upper small disc is positioned above the upper end surface of the rotor, and the lower small disc is positioned below the lower end surface of the rotor; axial air gaps are reserved between the upper small disc and the lower small disc and the end face of the rotor, control magnetic flux enters the receiving disc through the return air gap, a self-loop is axially formed, a thrust disc does not need to be additionally arranged on the rotor, the rotating speed of the rotor is optimized, and the coupling of an axial magnetic field and a radial magnetic field is reduced.

Description

Axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing

Technical Field

The invention relates to a non-mechanical contact magnetic suspension bearing, in particular to a three-degree-of-freedom spherical hybrid magnetic bearing which is suitable for a vehicle-mounted flywheel battery suspension support.

Background

The vehicle-mounted flywheel battery utilizes the magnetic suspension support and the rotational inertia of the flywheel to realize energy storage, and the requirement on the volume of the flywheel battery is relatively high due to the limited space of the electric automobile. The magnetic suspension bearing is a key component for providing support for the flywheel battery, and the volume of the magnetic suspension bearing directly influences the volume of the flywheel battery. The existing magnetic bearing is realized by additionally arranging a thrust disc on a rotor in the axial control design, so that the design not only increases the mass of the rotor, but also increases the friction and the wind resistance loss of a rotating shaft when a flywheel battery runs at a high speed; in addition, the thrust disk increases the rotor circumferential linear velocity, limiting the maximum rotational speed of the rotor.

The stator of the traditional three-degree-of-freedom hybrid magnetic bearing is of a cylindrical structure, and the corresponding rotor is also cylindrical. Although the magnetic bearing with the structure can ensure the stable suspension operation of the flywheel battery, the gyro effect is inevitably caused when the flywheel battery is interfered by the outside. Because the vehicle-mounted flywheel battery device can cause the flywheel shaft to be subjected to a large gyro moment in the constraint direction when a vehicle starts, suddenly stops, turns and the like, the flywheel shaft or the magnetic bearing is subjected to a large additional pressure, and the existing magnetic bearing structure is difficult to avoid the generation of a gyro effect.

Disclosure of Invention

The invention aims to improve the structure of the existing three-degree-of-freedom hybrid magnetic suspension bearing, solve the problems that the volume is overlarge, the maximum rotating speed of a rotor is limited, a gyro effect is easy to generate and the like, and provide the three-degree-of-freedom spherical hybrid magnetic bearing with an axial self-loop, which has a compact structure, optimized rotor rotating speed and high integration level.

The invention relates to an axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing, which adopts the technical scheme that: the whole structure of the permanent magnet synchronous motor is axially symmetrical up and down, an upper axial stator, an upper annular permanent magnet, a radial stator, a lower annular permanent magnet and a lower axial stator are sequentially coaxially sleeved outside a rotor from top to bottom, three radial stator poles are uniformly distributed on a radial stator yoke part along the circumferential direction, a radial control coil is wound on each radial stator pole, the upper axial stator and the lower axial stator are same in structure and are symmetrically distributed up and down and are composed of an upper disc, a middle disc and a receiving disc which are axially connected, the inner diameter of the middle disc is smaller than that of the upper disc and the receiving disc, an axial stator cavity is formed on the inner side of the middle disc, and the axial control coils are tightly attached to the upper axial stator cavity and the lower axial stator cavity; the inner end surface of each upper disc extends inwards along the radial direction to form a conical disc, the large end of each conical disc is connected with the upper disc, the small end of the conical disc above the upper disc extends above the upper end surface of the rotor, the small end of the conical disc below the lower end surface of the rotor extends below the lower end surface of the rotor, small discs are arranged between the upper end surface and the lower end surface of the rotor and the corresponding conical discs, the small discs are tightly attached to the upper surface and the lower surface of the corresponding conical discs, the small discs above the upper end surface of the rotor are located above the upper end surface of the rotor, and the small discs below the upper end surface of the rotor are located below the; axial air gaps are reserved between the upper small disc and the lower small disc and the end face of the rotor; the upper annular permanent magnet and the lower annular permanent magnet are axially magnetized and the magnetizing directions are opposite.

Further, the inner diameter of the small disc is equal to that of the conical disc, and the outer diameter of the small disc is equal to that of the upper end face of the rotor and smaller than that of the receiving disc.

Furthermore, the middle of the axial direction of the rotor is a hollow cylinder, the outer side wall of the hollow cylinder is a convex spherical surface, the inner surface of the pole shoe at the inner end of each radial stator pole is a concave spherical surface, the spherical centers of the concave spherical surface and the convex spherical surface are overlapped and radially matched, and a radial air gap is reserved between the concave spherical surface and the convex spherical surface.

Furthermore, the outer diameters of the upper disc, the middle disc and the receiving disc are equal, the inner diameter of the upper disc is smaller than that of the receiving disc, the lower surface of the upper disc above the upper disc protrudes above the upper end face of the rotor, and the upper surface of the lower disc below the upper disc protrudes below the lower end face of the rotor.

After the technical scheme is adopted, compared with the prior art, the invention has the beneficial effects that:

1. the axial stator of the invention is provided with the receiving disc at one side close to the radial stator, a return air gap is established between the rotor and the receiving disc, the control magnetic flux generated by the axial control coil enters the receiving disc through the return air gap, a self-loop is axially formed, two axial stators which are symmetrical up and down are adopted for axial control, and therefore, a thrust disc does not need to be additionally arranged on the rotor, thereby reducing the friction and the wind resistance loss of a rotating shaft, improving the axial control precision, being more beneficial to the high-speed operation of the rotor, optimizing the rotating speed of the rotor, and greatly reducing the coupling of an axial magnetic field and a radial magnetic field, wherein the length of the return air gap is one time of that of the radial air gap.

2. The opposite surfaces of the stator and the rotor of the invention both adopt spherical structures, when the magnetic bearing deflects and deviates, the radial stator and the spherical rotor of the spherical structures can lead the electromagnetic force to point to the spherical center of the rotor, thereby reducing the interference moment generated by the stator magnetic pole to the rotor and effectively inhibiting the generation of gyroscopic effect. Moreover, the spherical structure is more beneficial to multidimensional movement and more beneficial to positioning and working in space. In addition, the spherical structure enables the distribution of the air gap magnetic field to be more uniform and symmetrical, thereby being convenient for controlling and analyzing the rotor and improving the control precision of the magnetic bearing.

3. The invention has reasonable and compact structure arrangement and high integration level, effectively reduces the axial length of the rotor, is more favorable for inhibiting the gyro effect of the rotor, simplifies the structure of the magnetic bearing, reduces the volume, has light weight, simple mechanical processing and easy realization, and obviously reduces the processing cost.

Drawings

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

FIG. 2 is a top view of the radial stator of FIG. 1;

FIG. 3 is a block diagram of the rotor of FIG. 1;

FIG. 4 is a schematic view of the radial stator and rotor assembly of FIG. 1;

FIG. 5 is an enlarged view of a portion of the axial stator of FIG. 1;

FIG. 6 is an enlarged view of a portion of the structure of FIG. 1;

FIG. 7 is a partial schematic view of an assembled structure of the axial stator and rotor of FIG. 1;

FIG. 8 is a schematic diagram of the static passive levitation of the present invention;

FIG. 9 is a schematic diagram of radial two-degree-of-freedom balance control according to the present invention;

FIG. 10 is a schematic diagram of the axial single degree of freedom balance control of the present invention.

In the figure: 4. a radial stator; 7. a rotor; 11. an upper axial stator; 12. a lower axial stator; 14. an upper axial stator cavity; 15. a lower axial stator cavity; 21. an upper axial control coil; 22. a lower axial control coil; 31. an upper annular permanent magnet; 32. a lower annular permanent magnet; 41. 42, 43 radial stator poles; 51. an upper magnetic isolation aluminum ring; 52. a lower magnetic isolation aluminum ring; 71. a rotor upper end cylinder; 61. 62, 63, radial control coils; 72. a rotor lower end cylinder; 73. a rotor intermediate cylinder;

111. a small disc of the upper axial stator 11; 112. a conical disk of the upper axial stator 11; 113. an upper disc of the upper axial stator 11; 114. a middle disk of the upper axial stator 11; 115. a receiving disc of the upper axial stator 11;

121. a small disc of the lower axial stator 12; 122. a conical disk of the lower axial stator 12; 123. an upper disc of the lower axial stator 12; 124. a middle disk of the lower axial stator 12; 125. a receiving disk of the lower axial stator 12;

411. a concave spherical surface; 731. convex spherical surface.

Detailed Description

Referring to fig. 1, the whole of the present invention is a structure which is symmetrical up and down along an axial direction, a rotor 7 is arranged in the middle of the axial direction, and an upper axial stator 11, an upper annular permanent magnet 31, a radial stator 4, a lower annular permanent magnet 32 and a lower axial stator 12 are coaxially sleeved outside the rotor 7 from top to bottom in sequence. The outer diameters of the upper axial stator 11, the upper annular permanent magnet 31, the radial stator 4, the lower annular permanent magnet 32, and the lower axial stator 12 are the same. The radial stator 4 is sleeved outside the middle of the rotor 7, the upper axial stator 11 and the lower axial stator 12 are completely the same in structure and are arranged vertically symmetrically along the center of the rotor 7, and the upper annular permanent magnet 31 and the lower annular permanent magnet 32 are completely the same in structure and are arranged vertically symmetrically along the center of the rotor 7.

Referring to fig. 2, the yoke portion of the radial stator 4 is uniformly arranged with three radial stator poles, respectively,

radial stator poles

41, 42, 43, in the circumferential direction. The upper end surfaces and the lower end surfaces of the three

radial stator poles

41, 42, and 43 are flush with the upper end surface and the lower end surface of the yoke of the radial stator 4, respectively. A radial control coil, respectively

radial control coil

61, 62, 63, is wound on each

radial stator pole

41, 42, 43. The 3 radial control coils 61, 62, 63 are wound on the

radial stator poles

41, 42, 43 in a one-to-one correspondence, respectively.

As shown in fig. 3, the rotor 7 is a structure that is symmetrical up and down in the axial direction, and the middle is a hollow middle cylinder 73 with a convex spherical surface, and the outer side wall surface of the middle hollow cylinder 73 is processed into a convex spherical surface 731. The upper and lower ends are respectively the same hollow cylinder, namely an upper end cylinder 71 and a lower end cylinder 72. The lower end surface of the upper end column 71 and the upper end surface of the lower end column 72 are respectively connected to the upper and lower end surfaces of the middle cylinder 73 in a seamless manner. The inner and outer radii of the upper end cylinder 71 and the lower end cylinder 72 are equal. The inner diameter of the middle cylinder 73 is equal to the inner diameters of the upper end cylinder 71 and the lower end cylinder 72. The outer diameters of the upper end surface and the lower end surface of the intermediate cylindrical body 73 are equal to the outer diameters of the upper end cylinder 71 and the lower end cylinder 72, respectively.

As shown in fig. 4, the inner ends of the three

radial stator poles

41, 42, 43 have pole shoes with concave spherical surfaces on their inner surfaces. Taking the radial stator pole 41 as an example, the pole shoe surface of the radial stator pole 41 is processed into a concave spherical surface 411. Each concave spherical surface at the inner end of the three

radial stator poles

41, 42, 43 is radially opposite to the convex spherical surface 731 on the outer side surface of the middle cylinder 73 of the rotor 7, and a radial air gap of 0.5mm is maintained between the concave spherical surface and the convex spherical surface 731, and the concave spherical surface and the convex spherical surface 731 have the same thickness in the axial direction. When the rotor 7 is in the equilibrium position, the spherical centers of the convex spherical surface 731 of the intermediate cylindrical body 73 of the rotor 7 and the concave spherical surfaces of the

radial stator poles

41, 42, 43 coincide. Taking the arrangement structure of the radial stator pole 41 and the rotor 7 in fig. 4 as an example, the concave spherical surface 411 of the radial stator pole 41 and the convex spherical surface 731 of the rotor 7 are matched in the radial direction, and a radial gap of 0.5mm is left between the two.

As in the upper axial stator 11 of fig. 5, the upper axial stator 11 and the lower axial stator 12 have the same structure and are arranged vertically symmetrically. Taking the upper axial stator 11 as an example: in the middle of the upper axial stator 11 is a middle disk 114, the upper surface of the middle disk 114 is seamlessly connected with an upper disk 113, and the upper surface is seamlessly connected with a receiving disk 115. The middle disk 114 has the same outer diameter as the upper disk 113 and the receiving disk 115, but the middle disk 114 has a smaller inner diameter than the upper disk 113 and the receiving disk 115, thus forming the upper axial stator cavity 14 on the inside of the middle disk 114. The inner diameter of the upper disk 113 is smaller than the inner diameter of the receiving disk 115, and the inner diameter of the middle disk 114 is smaller than the inner diameter of the upper disk 113. A radial air gap remains between the inner surface of the receiving disc 115 and the rotor 7. The lower surface of the upper disk 113 is higher than the upper end surface of the rotor 7, i.e., protrudes above the upper end surface of the rotor 7. The inner end surface of the upper disc 113 extends radially inwardly of the conical disc 112, the cone angle of the conical disc 112 being 30 °. The big end of conical disc 112 is connected with upper portion disc 113, the tip of conical disc 112 stretches above rotor 7 up end, the tip lower surface of conical disc 112 is processed into the plane, fixedly connected with small disc 111 on the plane of tip lower surface, the plane on small disc 111 upper surface and the tip lower surface of conical disc 112 pastes together promptly, and small disc 111 is located rotor 7 up end top, small disc 111 installs between rotor 7 up end and conical disc 112, leave axial air gap between small disc 111 lower surface and the rotor 7 up end. The angle between the upper surface of the small circular disk 111 and the upper surface of the conical disk 112 is 15 °. The inner diameter of the small disk 111 is equal to the inner diameter of the conical disk 112, the outer diameter of the small disk 111 is equal to the outer diameter of the upper end cylinder 71 of the rotor 7, and the outer diameter of the small disk 111 is smaller than the inner diameter of the receiving disk 115.

As shown in fig. 1, 5, 6 and 7, the lower axial stator 12, which is composed of a lower upper disk 123, an intermediate middle disk 124 and an upper receiving disk 125, has the same structure as the upper axial stator 11 but is vertically symmetrical. Therefore, the upper surface of the upper disk 123 is higher than the lower end surface of the rotor 7 and protrudes below the lower end surface of the rotor 7. The small end of the conical disk 122 extended from the upper disk 123 extends below the lower end face of the rotor 7, and an axial air gap is left between the upper surface of the small disk 121 connected to the upper surface of the small end of the conical disk 122 and the lower end face of the rotor 7. Formed on the inside of the middle disk 124 is a lower axial stator cavity 15. The upper axial stator chamber 14 houses an upper axial control coil 21, the upper axial control coil 21 being in close contact with the upper disc 123, the middle disc 114 and the receiving disc 115. Likewise, a lower axial control coil 22 is mounted within the lower axial stator cavity 15. The receiving pans 115 and 125 are made of electrically pure iron, which is a material with good magnetic permeability.

Outside the central cylindrical body 73 of the rotor 7, the radial stator 4 is located axially between the upper ring magnet 31 and the lower ring magnet 32. An upper annular permanent magnet 31 is fixedly laminated between the upper axial stator 11 and the radial stator 4, and a lower annular permanent magnet 32 is fixedly laminated between the lower axial stator 12 and the radial stator 4. The inner diameter of the upper annular permanent magnet 31 is larger than that of the middle disk 113 of the upper axial stator 11, and the inner diameter of the lower annular permanent magnet 32 is larger than that of the middle disk 123 of the lower axial stator 12.

The inner side of the upper annular magnet 31 is provided with an upper magnetic-isolation aluminum ring 51, and the outer wall of the upper magnetic-isolation aluminum ring 51 is tightly attached to the inner wall of the upper annular magnet 31. The upper magnetic isolation aluminum ring 51 is laminated between the upper axial stator 11 and the radial stator 4, the upper end face of the upper magnetic isolation aluminum ring 51 is overlapped with the lower end face of the upper axial stator 11, and the lower end face of the upper magnetic isolation aluminum ring 51 is overlapped with the upper end face of the radial stator 4. The outer diameter of the upper magnetic shielding aluminum ring 51 is equal to the inner diameter of the upper annular magnet 31, and the inner diameter of the upper magnetic shielding aluminum ring 51 is equal to the inner diameter of the middle disk 114 of the upper axial stator 11. The lower magnetism isolating aluminum ring 52 is overlapped between the lower axial stator 12 and the radial stator 4, the lower end face of the lower magnetism isolating aluminum ring 52 is overlapped with the upper end face of the lower axial stator 12, the upper end face of the lower magnetism isolating aluminum ring 52 is overlapped with the lower end face of the radial stator 4, the side face of the lower magnetism isolating aluminum ring 52 is tightly attached to the inner wall of the lower annular magnet 32, the outer diameter of the lower magnetism isolating aluminum ring 52 is equal to the inner diameter of the lower annular magnet 42, and the inner diameter of the lower magnetism isolating aluminum ring 52 is equal to the inner diameter of the middle disc 124 of the lower axial stator 12.

The upper annular permanent magnet 31 and the lower annular permanent magnet 32 are identical in structure, made of high-performance rare earth materials neodymium iron boron, and axially magnetized, and the magnetizing directions of the upper annular permanent magnet 31 and the lower annular permanent magnet 32 are opposite.

As shown in fig. 8, when the rotor 7 is in the equilibrium position, an axial air gap of 0.5mm is maintained between the lower end surface of the small disc 111 of the upper axial stator 11 and the upper surface of the upper end cylinder 71 of the rotor 7, and a return air gap of 1mm is maintained between the inner wall of the receiving disc 115 of the upper axial stator 11 and the outer side surface of the upper end cylinder 71 of the rotor 7. The outer diameter of the upper end cylinder 71 of the rotor 7 is equal to the outer diameter of the small disc 111 of the upper axial stator 1. The inner diameter of the upper end cylinder 71 of the rotor 7 is smaller than the inner diameter of the small disk 111 of the upper axial stator 1. Similarly, the upper end face of the small circular disk 121 of the lower axial stator 12 maintains an axial air gap of 0.5mm in the axial direction with the lower end cylinder 72 of the rotor 7, and the inner wall of the receiving disk 125 of the lower axial stator 12 maintains a return air gap of 1mm in the radial direction with the outer wall of the lower end cylinder 72 of the rotor 7. The outer diameter of the lower end cylinder 72 of the rotor 7 is equal to the outer diameter of the small disc 121 of the lower axial stator 12. The inner diameter of the lower end cylinder 72 of the rotor 7 is smaller than the inner diameter of the small disk 121 of the lower axial stator 12.

When the invention works, the static passive suspension, radial two-degree-of-freedom balance and axial single-degree-of-freedom balance of the rotor 7 can be realized. In the aspect of radial control, alternating current three-phase power is supplied to the radial control coils 61, 62 and 63 arranged on the three-magnetic-pole

radial stator poles

41, 42 and 43, and the precise control of two degrees of freedom in the radial direction is realized by changing the current of the radial control coils 61, 62 and 63. In the aspect of axial control, the upper axial control coil 21 is energized with direct current to form an electromagnet with the upper axial stator 11, the lower axial control coil 22 is energized with direct current to form an electromagnet with the lower axial stator 12, the magnitude and direction of the stress on the rotor 7 in the axial direction are changed by changing the magnitude and direction of the control direct current, the control magnetic flux generated by the upper and lower axial control coils 21 and 22 enters the receiving

discs

115 and 125 through a return air gap between the rotor 7 and the receiving

discs

115 and 125, and a self-loop is formed in the axial direction, so that the control of one degree of freedom in the axial direction is realized. The method comprises the following specific steps:

1. the static passive suspension is realized: referring to fig. 8, the bias magnetic flux generated by the upper annular permanent magnet 31 and the bias magnetic flux generated by the lower annular permanent magnet 32 are, as shown by the dotted line and the arrow thereof in fig. 8, divided into two paths from the N pole of the upper annular permanent magnet 31, one path passes through the receiving disc 115 of the upper axial stator 11, the return air gap between the inner wall of the receiving disc 115 of the upper axial stator 11 and the upper end column 71 of the rotor 7 enters the upper end column 71 of the rotor 7, the middle column 73 of the rotor 7, the radial stator 4, and finally returns to the S pole of the upper annular permanent magnet 31; the other path passes through a receiving disc 115 of the upper axial stator 11, a middle disc 114 of the upper axial stator 12, an upper disc 113 of the upper axial stator 1, a conical disc 112 of the upper axial stator 11, a small disc 111 of the upper axial stator 11, an axial air gap between the inner wall of the small disc 111 of the axial stator 1 and the upper end column 71 of the rotor 7, enters the axial air gap, enters the upper end column 71 of the rotor 7, enters the middle cylinder 73 of the rotor 7, passes through the radial stator 4, and finally returns to the S pole of the upper annular permanent magnet 31. The bias magnetic flux generated by the lower annular permanent magnet 32 is divided into two paths from the N pole of the lower annular permanent magnet 32, one path passes through the receiving disc 125 of the lower axial stator 12, and the return air gap between the inner wall of the receiving disc 125 of the axial stator 12 and the lower end column 72 of the rotor 7 enters the lower end column 72 of the rotor 7, the middle cylinder 73 of the rotor 7, the radial stator 4 and finally returns to the S pole of the lower annular permanent magnet 32; the other path passes through a receiving disc 125 of the lower axial stator 12, a middle disc 124 of the lower axial stator 12, an upper disc 123 of the lower axial stator 12, a conical disc 122 of the lower axial stator 12, a small disc 121 of the lower axial stator 2, enters the lower end cylinder 72 of the rotor 7, the middle cylinder 73 of the rotor 7, the radial stator 4 through an axial air gap between the inner wall of the small disc 121 of the axial stator 12 and the lower end cylinder 72 of the rotor 7, and finally returns to the S pole of the lower annular permanent magnet 52. Taking the radial stator poles 41 as an example, when the rotor 7 is in the center equilibrium position, the central axis of the rotor 7 coincides with the axial central axis of the magnetic bearing. In the radial direction, radial breathing magnetic flux is generated between the rotor 7 and the pole shoe surface of the radial stator 4. In this way, radial breath magnetic fluxes generated between the rotor 3 and the surfaces of the pole shoes of the

radial stator poles

41, 42, and 43 are completely equal, so that the rotor 7 is balanced by the electromagnetic force in the radial direction, and the rotor 7 is suspended stably in the radial direction. In the axial direction, a downward air gap magnetic flux is generated between the inner wall of the small circular disc 121 of the upper axial stator 12 and the upper end cylinder 71 of the rotor 7, an upward air gap magnetic flux is generated between the inner wall of the small circular disc 121 of the lower axial stator 12 and the lower end cylinder 72 of the rotor 7, the total axial magnetic tension of the rotor 7 is balanced with the gravity of the rotor 3, and the rotor 7 is suspended stably in the axial direction.

2. Realizing radial two-degree-of-freedom balance: referring to fig. 9, when the rotor 7 is disturbed in the radial two-degree-of-freedom X, Y and deviates from the equilibrium position, the radial control coils 41, 42, 43 are energized, and the generated single magnetic flux points in the direction opposite to the position deviation, and a corresponding radial control magnetic levitation force is generated, so that the rotor 3 returns to the radial equilibrium position. Assuming that the rotor 3 is disturbed in the positive radial direction X to shift the equilibrium position, the radial control coils 41, 42, 43 are energized to generate control magnetic fluxes as indicated by thick solid lines and arrows thereof in fig. 9, and the upper annular permanent magnet 31 and the lower annular permanent magnet 32 generate bias magnetic fluxes as indicated by broken lines and arrows thereof in fig. 9, and the bias magnetic fluxes and the control magnetic fluxes passing through the

radial stator poles

41, 43 are opposite in direction, and the total magnetic flux is weakened. The bias flux and control flux in the radial stator poles 42 are in the same direction and the total flux is increased so that the single flux radial in the negative X-axis direction is increased and the rotor 7 is brought back to equilibrium by a magnetic pull F1 in the negative direction.

3. The realization of axial single-degree-of-freedom active control: referring to fig. 10, when the rotor 7 is shifted in position in the axial direction, the control magnetic flux generated by the axial control coil enters the receiving disc through the return air gap between the rotor and the receiving disc by changing the magnitude and direction of the control current, and a self-loop is formed in the axial direction, so that control of one degree of freedom in the axial direction is realized. By changing the magnitude of the axial air gap flux between the small disk 111 of the upper axial stator 11 and the upper end cylinder 71 of the rotor 7 and the magnitude of the axial air gap flux between the small disk 121 of the lower axial stator 12 and the lower end cylinder 72 of the rotor 7, a magnetic attraction force is generated at the axial air gap to return the rotor 7 to the axial directionThe equilibrium position is referenced. For example, when the rotor 7 is shifted downward, the upper axial control coil 21 and the lower axial control coil 22 are applied with axial control current to generate axial control magnetic flux as shown by the thick solid line and the arrow in fig. 10, the axial control magnetic flux passes through the return air gap to form a self-loop, the annular

permanent magnets

21 and 22 generate bias magnetic flux as shown by the dotted line and the arrow in fig. 10, it can be seen that the axial bias magnetic flux between the inner wall of the small disk 111 of the axial stator 11 and the upper end column 71 of the rotor 7 is opposite to the axial control direction, the downward magnetic flux is weakened, the axial bias magnetic flux between the inner wall of the small disk 121 of the axial stator 12 and the lower end column 72 of the rotor 7 is upward along the axial direction, and therefore the resultant electromagnetic force F received by the rotor 7 is_ZUpwards, the rotor 7 is pulled back to the axial equilibrium position, whereby one degree of freedom in the axial direction is controlled.

Claims

1. The utility model provides an axial is from spherical hybrid magnetic bearing of three degrees of freedom in return circuit, its overall structure is along the axial symmetry from top to bottom, and rotor (7) outer from last coaxial cover down has upper portion axial stator (11), upper portion annular permanent magnet (31), radial stator (4), lower part annular permanent magnet (32) and lower part axial stator (12) in proper order, and radial stator (4) yoke evenly arranges three radial stator utmost point along the circumferencial direction, and it has a radial control coil, characterized by to wind on every radial stator utmost point: the upper axial stator (11) and the lower axial stator (12) are the same in structure and are arranged in an up-down symmetrical mode and are formed by axially connecting an upper disc, a middle disc and a receiving disc, the inner diameter of the middle disc is smaller than that of the upper disc and the receiving disc, an axial stator cavity is formed on the inner side of the middle disc, and axial control coils are tightly attached to the upper axial stator cavity and the lower axial stator cavity; the inner end surface of each upper disc radially extends inwards to form a conical disc, the large end of each conical disc is connected with the upper disc, the small end of each conical disc above the upper disc extends above the upper end surface of the rotor (7), the small end of each conical disc below the upper disc extends below the lower end surface of the rotor (7), small discs are arranged between the upper end surface and the lower end surface of the rotor (7) and the corresponding conical discs, the small discs are tightly attached to the upper surface and the lower surface of the corresponding conical discs, the small discs above the upper end surface of the rotor (7) are located above the upper end surface of the rotor (7), and the small discs below the upper end surface of the rotor (7) are located below the lower end surface of the rotor (7); axial air gaps are reserved between the upper small disc and the lower small disc and the end face of the rotor (7); the upper annular permanent magnet (31) and the lower annular permanent magnet (32) are axially magnetized and have opposite magnetizing directions;

a hollow cylinder (73) is arranged in the middle of the rotor (7) in the axial direction, the outer side wall of the hollow cylinder (73) is a convex spherical surface (731), the inner surface of a pole shoe at the inner end of each radial stator pole is a concave spherical surface, the concave spherical surfaces are overlapped with the spherical centers of the convex spherical surfaces and are matched in the radial direction, and a radial air gap is reserved between the concave spherical surfaces and the convex spherical surfaces;

an upper annular permanent magnet (31) is fixedly laminated between the upper axial stator (11) and the radial stator (4), a lower annular permanent magnet (32) is fixedly laminated between the lower axial stator (12) and the radial stator (4), the inner diameter of the upper annular permanent magnet (31) is larger than that of a middle disk of the upper axial stator (11), and the inner diameter of the lower annular permanent magnet (32) is larger than that of a middle disk of the lower axial stator (12);

the radial control coil is electrified with alternating current three-phase power, and the current of the radial control coil is changed to realize radial two-degree-of-freedom control; the axial control coil is electrified with direct current, and the size and the direction of the direct current are changed to change the stress size and the stress direction of the rotor (7) so as to realize axial one-degree-of-freedom control.

2. The axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing according to claim 1, wherein: the inner diameter of the small disc is equal to that of the conical disc, and the outer diameter of the small disc is equal to that of the upper end face of the rotor (7) and is smaller than that of the receiving disc.

3. The axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing according to claim 1, wherein: the outer diameters of the upper disc, the middle disc and the receiving disc are equal, the inner diameter of the upper disc is smaller than that of the receiving disc, the lower surface of the upper disc above the upper disc protrudes above the upper end face of the rotor (7), and the upper surface of the upper disc below the upper disc protrudes below the lower end face of the rotor (7).

4. The axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing according to claim 1, wherein: the outer diameters of the upper axial stator (11), the upper annular permanent magnet (31), the radial stator (4), the lower annular permanent magnet (32) and the lower axial stator (12) are the same.

5. The axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing according to claim 1, wherein: the inner side wall of the upper annular magnet (31) is tightly attached to the upper magnetism-isolating aluminum ring (51), the inner side wall of the lower annular magnet (32) is tightly attached to the lower magnetism-isolating aluminum ring (52), and the inner diameters of the upper magnetism-isolating aluminum ring (51) and the lower magnetism-isolating aluminum ring (52) are equal to the inner diameter of the middle disk.

6. The axial self-loop three-degree-of-freedom spherical hybrid magnetic bearing according to claim 1, wherein: the cone angle of the conical disc is 30 degrees.