Five-degree-of-freedom bearingless permanent magnet synchronous motor with disc rotor

Abstract

The application provides a five-degree-of-freedom bearingless permanent magnet synchronous motor with a disc rotor, which comprises a stator, a rotor, a rotating shaft, a rotor disc and permanent magnets, the rotating shaft is located at the inner side of the stator, the permanent magnets are attached to the outer wall of the rotating shaft, and a radial air gap is left between the permanent magnets and the stator, two rotor discs are fixedly installed at the axial two ends of the rotating shaft, and an axial air gap is left between the rotor discs and the stator. The application adopts the design structure of the disc rotor, which not only enhances the heat dissipation area, but also improves the integration and power density of the system, and the rotor core is cancelled, the permanent magnets are directly attached to the surface of the rotating shaft, and the volume and weight of the system are reduced.

Description

Technical Field

[0001] This invention relates to the field of bearingless permanent magnet synchronous motor technology, specifically to a five-degree-of-freedom bearingless permanent magnet synchronous motor with a disc rotor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in large industrial equipment drives, industrial automation, new energy vehicles, aerospace, and other fields due to their advantages such as high efficiency, high power density, and high reliability. However, with the increasing demands for power and speed, traditional mechanical bearings and shafts are experiencing problems such as increased friction and severe heat generation. This not only increases mechanical losses but also shortens the lifespan of the mechanical bearings, limiting the application of PMSMs in high-power, high-speed scenarios. Therefore, combining bearingless motor technology with traditional PMSMs to create bearingless PMSMs with radial levitation capabilities, enabling high-speed, frictionless shaft operation, has become a major research focus.

[0003] Typically, bearingless permanent magnet synchronous motors can only achieve radial two-degree-of-freedom levitation. To achieve their application in five-degree-of-freedom levitation scenarios, additional radial and axial magnetic bearings are generally required. This undoubtedly increases the complexity of the system structure and the axial length of the rotor, and also limits the improvement of the system's critical speed. Therefore, exploring highly integrated five-degree-of-freedom bearingless permanent magnet synchronous motor systems is an important trend for further improving motor power density and reducing system size in the future. Summary of the Invention

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

[0005] To achieve the above and other objectives, the present invention is implemented by the following technical solution: The present invention provides a five-degree-of-freedom bearingless permanent magnet synchronous motor with a disc rotor, characterized in that it includes: a stator; a rotor, including a rotating shaft and a rotor disc, wherein the rotating shaft is located inside the stator, the two rotor discs are respectively fixedly installed at both axial ends of the rotating shaft, and an axial air gap is left between the rotor disc and the stator.

[0006] In one embodiment, the rotor further includes a permanent magnet, which is attached to the outer wall of the shaft, and a radial air gap is left between the permanent magnet and the stator.

[0007] In one embodiment, the stator includes a stator core, and a plurality of uniformly distributed stator radial teeth are formed on the inner wall of the stator core in a radially inward direction. A tooth groove is formed between two adjacent stator radial teeth, and a first winding and a second winding are sequentially arranged in the tooth groove in a radially inward direction.

[0008] In one embodiment, the number of stator radial tooth poles is a multiple of 6.

[0009] In one embodiment, eight evenly distributed stator axial teeth are formed at both ends of the stator core along the axial direction, and the stator axial teeth at both ends are aligned one by one, and an axial winding is wound on the stator axial teeth.

[0010] In one embodiment, the two sets of Y1 windings on one end of the stator axial tooth pole are first connected in reverse series, and then connected in forward series with the corresponding Y2 windings on the other end of the stator axial tooth pole; the two sets of X1 windings on one end of the stator axial tooth pole are first connected in reverse series, and then connected in forward series with the corresponding X2 windings on the other end of the stator axial tooth pole; the Z windings on the stator axial tooth pole are connected in forward series with each other. In one embodiment, the length of the stator axial tooth pole is 1 / 3 of the length of the stator core.

[0011] In one embodiment, the axial air gap length between the rotor disk and the stator axial tooth pole is equal to the radial air gap length between the stator radial tooth pole and the permanent magnet.

[0012] In one embodiment, the number of permanent magnets is 2, 4, or 8.

[0013] In one embodiment, the diameter of the rotor disk is equal to or greater than the outer diameter of the stator.

[0014] In one embodiment, both the rotating shaft and the rotor disk are made of ferromagnetic material.

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

[0016] 1. The present invention adopts a disc rotor design structure, which not only enhances the heat dissipation area, but also improves the system integration and power density;

[0017] 2. The motor of this invention eliminates the rotor core and directly attaches the permanent magnet to the surface of the shaft, reducing the size and weight of the system;

[0018] 3. The stator of this invention adopts a design of stator radial tooth poles (radial stator poles) and stator axial tooth poles (axial stator poles). By controlling the current in the first and second windings between the stator radial tooth poles, the two-degree-of-freedom radial levitation force of the motor can be realized; by controlling the current in the X1, Y1, X2 and Y2 windings on the stator axial tooth poles, the radial two-degree-of-freedom tilting motion of the motor can be realized; by controlling the current in the Z winding on the stator axial tooth poles, the axial single-degree-of-freedom motion of the motor can be realized, thereby realizing the levitation of the motor in five degrees of freedom. Attached Figure Description

[0019] Figure 1 The diagram shown is a three-dimensional structural schematic of a five-degree-of-freedom bearingless permanent magnet synchronous motor with a disc rotor according to the present invention.

[0020] Figure 2 The diagram shown is a three-dimensional structural schematic of the stator in this invention.

[0021] Figure 3 The image shown is a left view of the stator in this invention.

[0022] Figure 4 The image shown is a right view of the stator in this invention.

[0023] Figure 5 The diagram shows a cross-sectional view of the plane containing the X1 winding and the X2 winding when the motor is not eccentric in this invention.

[0024] Figure 6 The diagram shows a cross-sectional view of the plane containing the Y1 and Y2 windings when the motor is not eccentric.

[0025] Figure 7 The diagram shows a cross-sectional view of the plane containing the two coplanar Z-windings when the motor is not eccentric.

[0026] Figure 8 The diagram shows the magnetic flux path when the tilt angle is controlled according to the present invention.

[0027] Figure 9 The diagram shows the magnetic flux path during axial displacement control according to the present invention. Detailed Implementation

[0028] Please see Figures 1 to 9 The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0029] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the component designations in this specification, such as "first" and "second," are merely for distinguishing the described objects and have no sequential or technical meaning. Unless otherwise specified, the term "connection" in this invention includes both direct and indirect connections. The term "multiple" in this specification refers to two or more.

[0030] like Figure 1 As shown, this invention provides a five-degree-of-freedom bearingless permanent magnet synchronous motor with a disc rotor, including a stator 10 and a rotor 20. The rotor 20 includes a shaft 21, rotor discs 22, and permanent magnets 23. The shaft 21 is located inside the stator 10, and the permanent magnets 23 are directly attached to the outer wall of the shaft 21, with a radial air gap between the permanent magnets 23 and the stator 10. The number of permanent magnets 23 can be 2, 4, 8, etc.; the figure shows an embodiment with two permanent magnets 23. The axial length of the shaft 21 should be greater than the axial length of the stator 10. Two rotor discs 22 are respectively fixedly installed at both axial ends of the shaft 21, with an axial air gap between the rotor discs 22 and the stator 10. Specifically, the diameter of the rotor discs 22 can be equal to or slightly larger than the outer diameter of the stator 10. The rotor discs 22 can be fastened to the shaft 21 with screws or directly welded to the shaft 21. Specifically, both the rotating shaft 21 and the rotor disk 22 are made of ferromagnetic material.

[0031] like Figures 2-4 As shown, the stator 10 includes a stator core 11, stator radial tooth poles 12, and stator axial tooth poles 13. The stator core 11 is annular. Multiple uniformly distributed stator radial tooth poles 12 are formed radially inward on the inner wall of the stator core 11. The number of stator radial tooth poles 12 can be a multiple of 6, such as 6, 12, 18, or 24. The figure shows an embodiment with 24 stator radial tooth poles 12. The axial length of the stator radial tooth poles 12 can be equal to the axial length of the stator core 11. A tooth groove 121 is formed between two adjacent stator radial tooth poles 12. A first winding 31 and a second winding 32 are sequentially arranged radially inward within each tooth groove 121. Both the first winding 31 and the second winding 32 are three-phase distributed windings. The first winding 31 is a suspension winding used to generate a two-degree-of-freedom radial suspension force; the second winding 32 is a torque winding used to provide torque. The stator core 11 and stator radial tooth pole 12, along with the first winding 31 and the second winding 32, are conventional configurations in existing bearingless permanent magnet synchronous motors, and their working principles will not be elaborated here.

[0032] Furthermore, eight stator axial teeth 13 are formed outwardly at both ends of the stator core 11 along the axial direction. The included angle between two adjacent stator axial teeth 13 at the same end is 45°, and the stator axial teeth 13 at both ends are aligned one-to-one. A concentrated axial winding 33 is wound on each stator axial tooth 13. The length of the stator axial tooth 13 can be 1 / 3 of the length of the stator core 11.

[0033] like Figure 3 As shown, the axial winding 33 wound on the first tooth 1 and the fifth tooth 5 of the stator axial tooth pole 13 at one end of the stator core 11 can be defined as the Y1 winding, the axial winding 33 wound on the third tooth 3 and the seventh tooth 7 of the stator axial tooth pole 13 at one end of the stator core 11 can be defined as the X1 winding, and the axial winding 33 wound on the second tooth 2, the fourth tooth 4, the sixth tooth 6 and the eighth tooth 8 of the stator axial tooth pole 13 at both ends of the stator core 11 can be defined as the Z winding.

[0034] like Figure 4 As shown, the axial winding 33 wound on the first tooth 1 and the fifth tooth 5 of the stator axial tooth pole 13 at the other end of the stator core 11 can be defined as a Y2 winding, the axial winding 33 wound on the third tooth 3 and the seventh tooth 7 of the stator axial tooth pole 13 at the other end of the stator core 11 can be defined as an X2 winding, and the axial winding 33 wound on the second tooth 2, the fourth tooth 4, the sixth tooth 6 and the eighth tooth 8 of the stator axial tooth pole 13 at the other end of the stator core 11 can be defined as a Z winding.

[0035] Please combine Figure 3 and Figure 4 The two sets of Y1 windings are first connected in reverse series, and then connected in forward series with the corresponding Y2 winding; the two sets of X1 windings are first connected in reverse series, and then connected in forward series with the corresponding X2 winding, so as to realize the radial two-degree-of-freedom tilting motion of the motor by controlling the current in the X1, Y1, X2 and Y2 windings. Furthermore, all the Z windings are connected in forward series, so as to realize the axial single-degree-of-freedom motion of the motor by controlling the current in the Z winding.

[0036] Figure 5 This is a cross-sectional view of the plane containing the X1 and X2 windings of the motor described in this invention when it is not eccentric. The radial air gap between the stator radial tooth pole 12 and the permanent magnet 23 is h. r The axial air gaps between the third tooth 3 and the seventh tooth 7 of the stator axial tooth pole 13 at one end of the stator core 11 and the rotor disk 22 are respectively h x1 h x2 The axial air gaps between the third tooth 3 and the seventh tooth 7 of the stator axial tooth pole 13 at the other end of the stator core 11 and the other rotor disk 22 are respectively h x3 h x4 h r It can be equal to h x1 h x2 h x3 h x4.

[0037] Figure 6 This is a cross-sectional view of the plane containing the Y1 and Y2 windings of the motor described in this invention when it is not eccentric. The axial air gaps between the first tooth 1 and the fifth tooth 5 of the stator axial tooth pole 13 at one end of the stator core 11 and the rotor disk 22 are h, respectively. y1 h y2 The axial air gaps between the first tooth 1 and the fifth tooth 5 of the stator axial tooth pole 13 at the other end of the stator core 11 and the rotor disk 22 are respectively h y3 h y4 .

[0038] Figure 7 This is a cross-sectional view of the plane containing the two coplanar Z-windings of the motor described in this invention when it is not eccentric. The axial air gap between the second tooth 2, fourth tooth 4, sixth tooth 6, and eighth tooth 8 of the stator axial tooth poles 13 at one end of the stator core 11 and the rotor disk 22 is h. z1 The axial air gap between the second tooth 2, the fourth tooth 4, the sixth tooth 6, and the eighth tooth 8 in the stator axial tooth pole 13 at the other end of the stator core 11 and the rotor disk 22 is h. z2 .

[0039] Figure 8 The magnetic flux path diagram for tilt angle control according to the present invention is shown. Please refer to... Figure 5-6 and Figure 8 The Y1 winding, X1 winding, Y2 winding, and X2 winding are used to control the two-degree-of-freedom tilting motion of the rotor 20. Specifically, the Y1 winding and Y2 winding control the tilt angle θ in the x-direction of the rotor 20. x The X1 winding and the X2 winding control the y-direction tilt angle θ of the rotor 20. y Inclined at an angle θ in the x-direction x For example, during the control process, the permanent magnet 23 on the rotor 20 provides axial bias flux, and the bias flux path is shown by the solid arrow in the figure. When θ x When the angle is less than 0°, due to the influence of different air gap magnetic flux densities, the rotor 20 tilts clockwise, causing h to... y1 <h y2 h y4 <h y3 At this time, by controlling the excitation current in the Y1 winding and the Y2 winding, so that the direction of the magnetic flux generated by the current is as shown by the dashed arrow in the figure, the rotor 20 will be subjected to a counterclockwise magnetic pull, thereby pulling the rotor 20 back to θ. x =0° position. When θ x >0° and the tilt angle θ in the y directiony The control principle is similar to the principle described above, and will not be repeated here.

[0040] Figure 9 The magnetic flux path diagram for axial displacement control of this invention is shown. Please refer to... Figure 7 and Figure 8 All of the Z-windings are used to control the single-degree-of-freedom axial motion of the rotor 20. During control, the permanent magnet 23 on the rotor 20 still provides the axial bias flux, the path of which is shown by the solid arrow in the figure. The direction and magnitude of the current in the Z-windings can be determined based on the axial displacement z of the rotor 20. When z > 0, due to the influence of the different air gap magnetic flux density between the stator axial tooth poles 13 at both ends of the stator core 11 and the rotor disk 22, h... z1 h z2 The rotor 20 is subjected to a horizontal axial force to the right. At this time, by controlling the excitation current in each of the Z windings so that the direction of the magnetic flux generated by the current is as shown by the dashed arrow in the figure, the rotor 20 will be subjected to a horizontal magnetic pull to the left, thereby pulling the rotor 20 back to the z=0 position. The control principle is similar when z<0, and will not be elaborated here.

[0041] In summary, the rotor disk 22 structure design of this invention can enhance the heat dissipation area of ​​the rotor 20, improve the system integration, and increase power density. Furthermore, this invention eliminates the rotor core, directly attaching the permanent magnet 23 to the surface of the shaft 21, reducing the system's volume and weight. Simultaneously, the stator 10 employs a design of radial stator poles 12 (radial stator poles) and axial stator poles 13 (axial stator poles). By controlling the current in the first winding 31 and the second winding 32 between the radial stator poles 12, the two-degree-of-freedom radial levitation force of the motor can be achieved. By controlling the current in the X1, Y1, X2, and Y2 windings on the axial stator poles 13, the radial two-degree-of-freedom tilting motion of the motor can be achieved. By controlling the current in the Z winding on the axial stator poles 13, the axial single-degree-of-freedom motion of the motor can be achieved, thus realizing the motor's levitation in five degrees of freedom.

[0042] Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability. The above embodiments are merely illustrative of the principles and effects of this invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of this invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A five-degree-of-freedom bearingless permanent magnet synchronous motor with a disc rotor, characterized in that, include: stator; The rotor includes a rotating shaft and rotor disks, the rotating shaft being located inside the stator; the two rotor disks are respectively fixedly installed at both ends of the rotating shaft, and an axial air gap is left between the rotor disks and the stator; The rotor also includes a permanent magnet, which is directly attached to the outer wall of the rotating shaft, and a radial air gap is left between the permanent magnet and the stator; The stator includes a stator core, and a plurality of uniformly distributed stator radial teeth are formed on the inner wall of the stator core in a radially inward direction. A tooth groove is formed between two adjacent stator radial teeth, and a first winding and a second winding are arranged sequentially in the tooth groove in a radially inward direction. The stator core has eight evenly distributed stator axial teeth at both ends, with each axial tooth aligned with the others. Axial windings are wound around each stator axial tooth. Specifically, two sets of Y1 windings on one end of the stator axial tooth are first connected in reverse series, and then connected in forward series with the corresponding Y2 windings on the other end of the stator axial tooth. Similarly, two sets of X1 windings on one end of the stator axial tooth are first connected in reverse series, and then connected in forward series with the corresponding X2 windings on the other end of the stator axial tooth. All Z windings on the stator axial tooth are connected in forward series with each other. Both the rotating shaft and the rotor disk are made of ferromagnetic material.

2. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that, The number of stator radial tooth poles is a multiple of 6.

3. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that, The length of the stator axial tooth pole is 1 / 3 of the length of the stator core.

4. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that, The axial air gap length between the rotor disk and the stator axial tooth pole is equal to the radial air gap length between the stator radial tooth pole and the permanent magnet.

5. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that, The number of permanent magnets is 2, 4, or 8.

6. The five-degree-of-freedom bearingless permanent magnet synchronous motor according to claim 1, characterized in that, The diameter of the rotor disk is equal to or greater than the outer diameter of the stator.

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