A five-degree-of-freedom bearingless permanent magnet synchronous motor

Abstract

The present invention provides a five-degree-of-freedom bearingless permanent magnet synchronous motor, comprising a stator, including a first stator, a second stator, and a third stator, wherein the first stator is connected to the second stator and the third stator at both axial ends; a plurality of first stator poles uniformly distributed in the radial direction are provided on the inner wall of the first stator, a slot is formed between two adjacent first stator poles, and a first winding and a second winding are sequentially arranged in the slots radially inward; eight second stator poles uniformly distributed in the radial direction are provided on the inner wall of the second stator, and an excitation winding is provided on the second stator poles; the structure of the third stator is identical to that of the second stator, and the third stator poles are aligned one-to-one with the second stator poles; and a rotor comprising a rotor core, a permanent magnet, and a rotating shaft. The present invention adopts a design structure in which three stators are connected, which can achieve suspension of the motor in five degrees of freedom, while significantly shortening the rotating shaft length, improving system integration, and increasing power density.

Description

Technical Field

[0001] The present invention relates to the technical field of bearingless permanent magnet synchronous motors, and in particular to a five-degree-of-freedom bearingless permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors (PMSMs), with their high efficiency and power density, are widely used in large-scale industrial equipment drives, new energy vehicles, aerospace, and other fields. With the increasing demand for power and speed, traditional mechanical bearings will experience increased friction and severe heat generation. This not only increases mechanical losses but also shortens bearing life, making them unable to meet the demands of high-power and high-speed applications. Therefore, bearingless motor technology can be applied to PMSMs, eliminating the mechanical bearings in the original system and enabling traditional PMSMs to also have radial suspension capabilities, thereby reducing system losses and extending system life.

[0003] However, bearingless permanent magnet synchronous motors only achieve two degrees of freedom (DOF) of radial suspension. Two radial magnetic bearings and one axial magnetic bearing are required to achieve five degrees of freedom. This design, employing magnetic bearings, not only increases structural complexity, hindering the design of an integrated structure, but also increases the system's axial length, limiting the critical speed. Therefore, it is imperative to explore a more integrated, five-DOF bearingless permanent magnet synchronous motor. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a five-degree-of-freedom bearingless permanent magnet synchronous motor.

[0005] In order to achieve the above objectives and other objectives, the present invention is implemented by including the following technical solutions: The present invention provides a five-degree-of-freedom bearingless permanent magnet synchronous motor, characterized in that it includes: a stator, including a first stator, a second stator and a third stator, the axial ends of the first stator are respectively connected to the second stator and the third stator; a plurality of first stator poles uniformly distributed in the radial direction are provided on the inner wall of the first stator, a tooth slot is formed between two adjacent first stator poles, and a first winding and a second winding are sequentially provided in the tooth slot inwardly in the radial direction; 8 second stator poles uniformly distributed in the radial direction are provided on the inner wall of the second stator , an excitation winding is provided on the second stator pole; the structure of the third stator is exactly the same as that of the second stator, and 8 third stator poles uniformly distributed in the radial direction are provided on the inner wall of the third stator, and an excitation winding is provided on the third stator pole; the third stator pole is aligned with the second stator pole one by one; the rotor is located on the inner side of the stator, and includes a rotor core, a permanent magnet and a rotating shaft, and a plurality of uniformly distributed grooves are provided on the outer wall of the rotor core; the permanent magnet is placed in the groove; the rotating shaft passes through the center of the rotor core; wherein an air gap h is formed between the first stator pole and the permanent magnet r The first, third, fifth, and seventh teeth in the second stator pole are coplanarly arranged, and the first, third, fifth, and seventh teeth in the third stator pole are coplanarly arranged; and a first axial air gap h1 is formed between the first, third, fifth, and seventh teeth in the second stator pole, the first, third, fifth, and seventh teeth in the third stator pole, and the rotor core; a first radial air gap h2 is formed between the first, third, fifth, and seventh teeth in the second stator pole, the first, third, fifth, and seventh teeth in the third stator pole, and the rotating shaft; The second, fourth, sixth and eighth teeth in the second stator pole are coplanarly arranged, and the second, fourth, sixth and eighth teeth in the third stator pole are coplanarly arranged; a second axial air gap h3 is formed between the second, fourth, sixth and eighth teeth in the second stator pole and the rotor core; a second radial air gap h4 is formed between the second, fourth, sixth and eighth teeth in the second stator pole and the rotating shaft; and h r =h2=h3,h2

[0006] ​In one embodiment, the Y1 winding on the second stator is first connected in series with the X1 winding on the second stator in a forward direction, and then connected in series with the Y2 winding and the X2 winding on the third stator pole in a reverse direction; the Z windings on the second and fourth tooth poles in the second stator are connected in series in a forward direction with the Z windings on the sixth and eighth tooth poles in the third stator; and the Z windings on the sixth and eighth tooth poles in the second stator are connected in series in a reverse direction with the Z windings on the second and fourth tooth poles in the third stator.

[0007] In one embodiment, h1=2h3, h4=2h2.

[0008] In one embodiment, the surface of the permanent magnet facing the first stator is an N pole, and the surface facing the rotor is an S pole.

[0009] In one embodiment, the axial length of the permanent magnet is equal to the axial length of the first stator pole, and the axial length of the permanent magnet is smaller than the axial length of the rotor core.

[0010] In one embodiment, the number of the first stator poles is a multiple of 6.

[0011] In one embodiment, the number of the grooves and the permanent magnets is 2, 4 or 8.

[0012] In one embodiment, the axial length of the rotating shaft is equal to the axial length of the stator.

[0013] In one embodiment, end surfaces of the first, third, fifth and seventh tooth poles in the second stator poles away from the first stator are flush with the end surface of the second stator away from the first stator.

[0014] In one embodiment, two axial ends of the first stator are connected to the second stator and the third stator respectively through magnetic conductive rings.

[0015] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0016] 1. The present invention adopts a design structure in which three stators are connected to a magnetic ring, which not only greatly shortens the length of the rotating shaft, but also improves the integration of the system and increases the power density;

[0017] 2. The present invention uses permanent magnets of the same polarity to provide radial and axial bias magnetic fluxes respectively, thereby improving the utilization rate of the permanent magnets;

[0018] 3. The present invention realizes two-degree-of-freedom radial suspension force by controlling the current in the first winding and the second winding; realizes radial two-degree-of-freedom tilting motion by controlling the current in the X1 winding, Y1 winding, X2 winding and Y2 winding; realizes axial single-degree-of-freedom motion by controlling the current in the Z winding, thereby realizing suspension of the motor in five degrees of freedom. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shown is a schematic diagram of the three-dimensional structure of a five-degree-of-freedom bearingless permanent magnet synchronous motor according to the present invention.

[0020] Figure 2A It shows a schematic diagram of the three-dimensional structure of the first stator and rotor in the present invention.

[0021] Figure 2B Shown is a cross-sectional view of a first stator and rotor in the present invention.

[0022] Figure 3 Shown is a cross-sectional view of the second stator in the present invention.

[0023] Figure 4 Shown is a cross-sectional view of the third stator in the present invention.

[0024] Figure 5 Shown is a diagram showing the positional relationship between the first and fifth tooth poles of the second and third stators and the rotor in the present invention.

[0025] Figure 6 The figure shows the magnetic flux path diagram during tilt angle control according to the present invention.

[0026] Figure 7 Shown is a diagram showing the positional relationship between the second and sixth tooth poles of the second and third stators and the rotor in the present invention.

[0027] Figure 8 The diagram shows the magnetic flux path during axial displacement control according to the present invention.

[0028] Figure 9A Shown as I in the present invention X1 =5A, I X2 =5A when the axial magnetic flux path distribution is obtained by simulation.

[0029] Figure 9B Shown as I in the present invention X1 =5A, I X2 =5A when the axial magnetic density cloud diagram is simulated.

[0030] Figure 10A Shown as I in the present invention Z = 10A when the axial magnetic flux path distribution diagram.

[0031] Figure 10B Shown as I in the present invention Z =Axial magnetic density cloud diagram when 10A. DETAILED DESCRIPTION

[0032] See also Figure 1 to Figure 1 0. The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0033] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for those skilled in the art to understand and read. They are not used to limit the limiting conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportional relationship, or adjustment of size, without affecting the efficacy and purpose that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. At the same time, the serial numbers assigned to the components in this specification, such as "first", "second", etc., are only used to distinguish the objects being described and do not have any order or technical meaning. The "connection" mentioned in the present invention, unless otherwise specified, includes direct and indirect connections. The "multiple" mentioned in this specification refers to two or more.

[0034] like Figure 1 As shown, the present invention provides a five-degree-of-freedom bearingless permanent magnet synchronous motor, including a stator 10 and a rotor 20. The stator 10 includes a first stator 11, a second stator 12, a third stator 13 and a magnetic ring 14. The axial ends of the first stator 11 are connected to the second stator 12 and the third stator 13 through a magnetic ring 14 respectively. The magnetic ring 14 is mainly used to better connect the magnetic circuit between the first stator 11 and the second stator 12 and the third stator 13, so the provision of the magnetic ring 14 is not necessary. The rotor 20 is located on the inner side of the stator 10, and an air gap is left between it and the stator 10. The axial length of the rotor 20 can be equal to the axial length of the stator 10.

[0035] like Figure 2A and Figure 2BAs shown, the first stator 11 includes a first stator core 111 and a first stator pole 112. The first stator core 111 is annular, and a plurality of first stator poles 112 are uniformly distributed radially on the inner wall of the first stator core 111. The number of first stator poles 112 can be a multiple of 6, such as 6, 12, 18, or 24. The figure shows an embodiment in which the number of first stator poles 112 is 24. The axial length of the first stator pole 112 can be equal to or less than the axial length of the first stator core 111. A slot 113 is formed between adjacent first stator poles 112. A first winding 41 and a second winding 42 are sequentially arranged radially inwardly in each slot 113. The axial length of the first winding 41 and the second winding 42 can be equal to the axial length of the slot 113. The first winding 41 and the second winding 42 are both three-phase distributed windings. The first winding 41 is a suspension winding for generating a two-degree-of-freedom radial suspension force; the second winding 42 is a torque winding for providing torque. The first stator 11 and the first and second windings 41, 42 are all conventional configurations in existing bearingless permanent magnet synchronous motors, and their operating principles are not further described here.

[0036] The rotor 20 includes a rotor core 21, permanent magnets 22 and a rotating shaft 23. The axial length of the rotor core 21 can be equal to or greater than the axial length of the first stator 11. A plurality of evenly distributed grooves 211 are provided on the outer wall of the rotor core 21. The permanent magnets 22 are placed in the grooves 211. The number of the permanent magnets 22 is the same as the number of the grooves 211. The number of the grooves 211 and the permanent magnets 22 can be 2, 4 or 8, etc. The figure shows an embodiment in which the number of the grooves 211 and the permanent magnets 22 is 4. The axial length of the permanent magnet 22 can be equal to the axial length of the first stator pole 112. The axial length of the permanent magnet 22 can be less than the axial length of the rotor core 21. For example, the axial length of the permanent magnet 22 is equal to 2 / 3 of the axial length of the rotor core 21. The rotating shaft 23 runs through the center of the rotor core 21. Please review Figure 1 , the axial length of the rotating shaft 23 may be equal to the axial length of the stator 10 .

[0037] Furthermore, all the permanent magnets 23 are installed in the same polarity, that is, the surface of the permanent magnet 23 facing the first stator 11 is the N pole, and the surface facing the rotor 20 is the S pole, thereby providing radial and axial bias fluxes for the motor at the same time.

[0038] like Figure 3As shown, the second stator 12 includes a second stator core 121 and eight second stator poles 122 uniformly arranged radially on the inner wall of the second stator core 121. The angle between two adjacent second stator poles 122 is 45°, and each second stator pole 122 is installed with an independently controlled excitation winding 43.

[0039] Please combine Figure 3 and Figure 1 The axial length of the second stator pole 122 is less than the axial length of the second stator core 121. The first tooth pole 1, the third tooth pole 3, the fifth tooth pole 5, and the seventh tooth pole 7 in the second stator pole 122 are arranged coplanarly. Specifically, the first tooth pole 1, the third tooth pole 3, the fifth tooth pole 5, and the seventh tooth pole 7 in the second stator pole 122 are evenly arranged in the radial direction on the side of the second stator core 121 away from the first stator 11. Furthermore, the end surfaces of the first tooth pole 1, the third tooth pole 3, the fifth tooth pole 5, and the seventh tooth pole 7 in the second stator pole 122 away from the first stator 11 can be flush with the end surface of the second stator core 121 away from the first stator 11.

[0040] The second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the second stator pole 122 are arranged in the same plane. Specifically, the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the second stator pole 122 are evenly arranged in the radial direction in the middle part of the second stator core 121, and the angle between the even tooth pole and the adjacent odd tooth pole is 45°.

[0041] Furthermore, the excitation winding 43 arranged on the third tooth pole 3 and the seventh tooth pole 7 in the second stator pole 122 can be defined as an X1 winding; the excitation winding 43 arranged on the first tooth pole 1 and the fifth tooth pole 5 in the second stator pole 122 can be defined as a Y1 winding; the excitation winding 43 arranged on the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the second stator pole 122 can be defined as a Z winding.

[0042] Please combine Figure 4 and Figure 1 The structure of the third stator 13 is identical to that of the second stator 12. The third stator 13 includes a third stator core 131 and eight third stator poles 132 radially and evenly arranged on the inner wall of the third stator core 131. The angle between two adjacent third stator poles 132 is 45°. Each third stator pole 132 is mounted with an independently controlled excitation winding 43.

[0043] The first pole tooth 1, the third pole tooth 3, the fifth pole tooth 5, and the seventh pole tooth 7 in the third stator pole 132 are coplanarly arranged, and the first pole tooth 1, the third pole tooth 3, the fifth pole tooth 5, and the seventh pole tooth 7 in the third stator pole 132 are aligned one by one with the first pole tooth 1, the third pole tooth 3, the fifth pole tooth 5, and the seventh pole tooth 7 in the second stator pole 122. Specifically, the first pole tooth 1, the third pole tooth 3, the fifth pole tooth 5, and the seventh pole tooth 7 in the third stator pole 132 are evenly arranged in the radial direction on the side of the third stator core 131 away from the first stator 11. Furthermore, the end surfaces of the first pole tooth 1, the third pole tooth 3, the fifth pole tooth 5, and the seventh pole tooth 7 in the third stator pole 132 away from the first stator 11 can be flush with the end surface of the third stator core 131 away from the first stator 11.

[0044] The second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the third stator pole 132 are arranged in the same plane. Specifically, the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the third stator pole 132 are evenly arranged in the radial direction in the middle part of the third stator core 131, and the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the third stator pole 132 are aligned one by one with the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the second stator pole 122.

[0045] Furthermore, the excitation winding 43 arranged on the third tooth pole 3 and the seventh tooth pole 7 in the third stator pole 132 can be defined as an X2 winding; the excitation winding 43 arranged on the first tooth pole 1 and the fifth tooth pole 5 in the third stator pole 132 can be defined as a Y2 winding; the excitation winding 43 arranged on the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 in the third stator pole 132 can be defined as a Z winding.

[0046] Please combine Figure 3 and Figure 4 The Y1 winding is first connected in series with the X1 winding in the forward direction, and then in series with the Y2 winding and the X2 winding in the reverse direction, so as to achieve radial two-degree-of-freedom tilting motion of the motor by controlling the current in the X1 winding, the Y1 winding, the X2 winding, and the Y2 winding. The Z winding on the second tooth pole 2 and the fourth tooth pole 4 in the second stator 12 is connected in series with the Z winding on the sixth tooth pole 6 and the eighth tooth pole 8 in the third stator 13 in the forward direction, and the Z winding on the sixth tooth pole 6 and the eighth tooth pole 8 in the second stator 12 is connected in series with the Z winding on the second tooth pole 2 and the fourth tooth pole 4 in the third stator 13 in the reverse direction, so as to achieve axial single-degree-of-freedom motion of the motor by controlling the current in the Z winding.

[0047] like Figure 5As shown, an air gap h is formed between the first stator 11 and the permanent magnet 22. r A first axial air gap h1 is formed between the first tooth pole 1 and the fifth tooth pole 5 in the second stator pole 122, the first tooth pole 1 and the fifth tooth pole 5 in the third stator pole 132, and the rotor core 21; a first radial air gap h2 is formed between the first tooth pole 1 and the fifth tooth pole 5 in the second stator pole 122, the first tooth pole 1 and the fifth tooth pole 5 in the third stator pole 132, and the rotating shaft 3; the size relationship between the air gaps satisfies: h r =h2

[0048] Although not shown in the figures, since the first tooth pole 1, the third tooth pole 3, the fifth tooth pole 5, and the seventh tooth pole 7 of the second stator pole 122 are arranged coplanarly, and the first tooth pole 1, the third tooth pole 3, the fifth tooth pole 5, and the seventh tooth pole 7 of the third stator pole 132 are arranged coplanarly, a first axial air gap h1 is formed between the third tooth pole 3 and the seventh tooth pole 7 of the second stator pole 122, the third tooth pole 3 and the seventh tooth pole 7 of the third stator pole 132, and the rotor core 21; and a first radial air gap h2 is formed between the third tooth pole 3 and the seventh tooth pole 7 of the second stator pole 122, the third tooth pole 3 and the seventh tooth pole 7 of the third stator pole 132 and the rotating shaft 3.

[0049] Please combine Figure 6 , due to h r =h2 x , X1 and X2 windings control the y-direction tilt angle θ of the rotor 20 y . Tilt angle θ in the x direction x For example, during the control process, the permanent magnet 22 on the rotor 20 provides an axial bias flux, and the bias flux path is shown as the solid arrow in the figure. x <0°, the rotor 20 tilts clockwise due to the influence of different air gap magnetic flux density. At this time, the excitation current in the Y1 and Y2 windings can be controlled so that the direction of the magnetic flux generated by the current is as shown by the dotted arrow in the figure, so that the rotor 20 is subjected to a counterclockwise magnetic pull, and the rotor 20 can be pulled back to the θ=0° position. x >0° and the y-direction tilt angle θ y The control principle is similar to the above principle and will not be repeated here.

[0050] like Figure 7 ​​As shown, an air gap h is formed between the first stator 11 and the permanent magnet 22. r , a second axial air gap h3 is formed between the second tooth pole 2 and the sixth tooth pole 6 of the second stator pole 122, the second tooth pole 2 and the sixth tooth pole 6 of the third stator pole 132 and the rotor core 21, and a second radial air gap h4 is formed between the second tooth pole 2 and the sixth tooth pole 6 of the second stator pole 122, the second tooth pole 2 and the sixth tooth pole 6 of the third stator pole 132 and the rotating shaft 23. The following dimensional relationship is satisfied among the air gaps: h r = h3 < h4.

[0051] Although not shown in the figure, since the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 of the second stator pole 122 are arranged coplanarly, and the second tooth pole 2, the fourth tooth pole 4, the sixth tooth pole 6 and the eighth tooth pole 8 of the third stator pole 132 are arranged coplanarly. Therefore, a second axial air gap h3 is formed between the fourth tooth pole 4 and the eighth tooth pole 8 of the second stator pole 122, the fourth tooth pole 4 and the eighth tooth pole 8 of the third stator pole 132 and the rotor core 21; a second radial air gap h4 is formed between the fourth tooth pole 4 and the eighth tooth pole 8 of the second stator pole 122, the fourth tooth pole 4 and the eighth tooth pole 8 of the third stator pole 132 and the rotating shaft 23.

[0052] Please refer to Figure 8 , because h3 < h4, the single - degree - of - freedom axial movement control of the rotor 20 can be achieved by controlling the magnitude of the excitation current in the Z winding. During the control process, the axial bias magnetic flux is still provided by the permanent magnet 22 on the rotor 20, and the bias magnetic flux path is shown by the solid arrows in the figure. Different from Figure 6 , because h3 < h4, the magnetic flux will close through the rotor core 21. The direction and magnitude of the excitation current in the Z winding can be judged according to the axial displacement z of the rotor 20. When z < 0, affected by the magnetic flux density of different air gaps, the rotor 20 is subjected to an axial force directed horizontally to the left. Therefore, by controlling the excitation current in the Z winding, when the magnetic flux direction generated by its current is shown by the dashed arrow in the figure, the rotor 20 can be subjected to a magnetic pulling force directed horizontally to the right, so that the rotor 20 can be pulled back to the z = 0 position. When z > 0, the control principle is similar and will not be elaborated here.

[0053] Figure 9A and Figure 9B respectively show the axial magnetic flux path distribution diagram and the magnetic flux density cloud diagram obtained by simulation when I X1 = 5A and I X2 = 5A in the present invention. In the simulation example, h1 = 2h3 and h4 = 2h2 are satisfied. Please refer to Figure 6When a 5A excitation current is passed through the X1 winding and the X2 winding, the radial air gap magnetic flux between the fifth tooth pole 5 in the second stator 122 and the rotating shaft 23 is greater than the radial air gap magnetic flux between the first tooth pole 1 in the second stator 122 and the rotating shaft 23, and the radial air gap magnetic flux between the first tooth pole 1 in the third stator 122 and the rotating shaft 23 is greater than the radial air gap magnetic flux between the fifth tooth pole 5 in the third stator 122 and the rotating shaft 23. Therefore, the rotor 20 is subjected to a counterclockwise magnetic pull.

[0054] Figure 10A and Figure 10B The present invention is respectively Z =10A, the axial magnetic flux path distribution diagram and magnetic density cloud diagram obtained by simulation, in the simulation example, h1=2h3, h4=2h2. Figure 8 When only the excitation current is passed through the Z winding, the axial air gap magnetic flux between the third stator pole 132 and the rotor core 21 is greater than the axial air gap magnetic flux between the second stator pole 122 and the rotor core 21, so the rotor 20 will be subjected to a horizontal rightward magnetic pull.

[0055] In summary, the present invention utilizes a three-stator structure and a design with different rotor-stator air gap sizes. By controlling the currents in the first and second windings, the motor's two-degree-of-freedom radial suspension force is achieved. By controlling the currents in the X1, Y1, X2, and Y2 windings, the motor's radial two-degree-of-freedom tilting motion is achieved. By controlling the current in the Z winding, the motor's axial single-degree-of-freedom motion is achieved, thereby achieving suspension of the motor in five degrees of freedom. Compared to existing technologies, this eliminates the need for additional magnetic bearings, significantly shortening the shaft length while also improving system integration and power density.

[0056] Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial value. The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by persons of ordinary skill in the art without departing from the spirit and technical concepts disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A five-degree-of-freedom bearingless permanent magnet synchronous motor, characterized in that: include: The stator comprises a first stator, a second stator and a third stator, wherein the axial ends of the first stator are respectively connected to the second stator and the third stator; A plurality of first stator poles uniformly distributed in the radial direction are provided on the inner wall of the first stator, a slot is formed between two adjacent first stator poles, and a first winding and a second winding are sequentially provided in the slot inwardly in the radial direction; The inner wall of the second stator is provided with 8 second stator poles evenly distributed in the radial direction, and the second stator poles are provided with an excitation winding; The structure of the third stator is identical to that of the second stator. Eight third stator poles are evenly distributed in the radial direction on the inner wall of the third stator. Excitation windings are provided on the third stator poles. The third stator poles are aligned one-to-one with the second stator poles. The rotor is located inside the stator and includes a rotor core, permanent magnets, and a rotating shaft. The outer wall of the rotor core is provided with a plurality of evenly distributed grooves; the permanent magnets are placed in the grooves; and the rotating shaft runs through the center of the rotor core. in, An air gap h is formed between the first stator pole and the permanent magnet. r ; The first, third, fifth, and seventh teeth in the second stator pole are coplanarly arranged, and the first, third, fifth, and seventh teeth in the third stator pole are coplanarly arranged; and a first axial air gap h1 is formed between the first, third, fifth, and seventh teeth in the second stator pole, the first, third, fifth, and seventh teeth in the third stator pole, and the rotor core; and a first radial air gap h2 is formed between the first, third, fifth, and seventh teeth in the second stator pole, the first, third, fifth, and seventh teeth in the third stator pole, and the rotating shaft; The second, fourth, sixth, and eighth teeth in the second stator pole are coplanarly arranged, and the second, fourth, sixth, and eighth teeth in the third stator pole are coplanarly arranged; a second axial air gap h3 is formed between the second, fourth, sixth, and eighth teeth in the second stator pole, the second, fourth, sixth, and eighth teeth in the third stator pole, and the rotor core; a second radial air gap h4 is formed between the second, fourth, sixth, and eighth teeth in the second stator pole, the second, fourth, sixth, and eighth teeth in the third stator pole, and the rotating shaft; And h r =h2=h3,h2 <h1,h3<h4。 2. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that: The Y1 winding on the second stator is first connected in series with the X1 winding on the second stator in the forward direction, and then connected in series with the Y2 winding and X2 winding on the third stator pole in the reverse direction; the Z winding on the second and fourth tooth poles in the second stator is connected in series with the Z winding on the sixth and eighth tooth poles in the third stator in the forward direction; the Z winding on the sixth and eighth tooth poles in the second stator is connected in series with the Z winding on the second and fourth tooth poles in the third stator in the reverse direction.

3. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 2, characterized in that: h1=2h3, h4=2h2.

4. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 2 or 3, characterized in that: The surface of the permanent magnet facing the first stator is an N pole, and the surface facing the rotor is an S pole.

5. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 4, characterized in that: The axial length of the permanent magnet is equal to the axial length of the first stator pole, and the axial length of the permanent magnet is smaller than the axial length of the rotor core.

6. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 5, characterized in that: The number of the first stator poles is a multiple of 6.

7. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 6, characterized in that: The number of the grooves and the permanent magnets is 2, 4 or 8.

8. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that: The axial length of the rotating shaft is equal to the axial length of the stator.

9. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that: End surfaces of the first, third, fifth and seventh tooth poles in the second stator poles away from the first stator are flush with the end surface of the second stator away from the first stator.

10. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that: The axial ends of the first stator are connected to the second stator and the third stator through magnetic conductive rings respectively.

Images