Rotor coreless multi-disk axial flux permanent magnet motor and operating method

Abstract

The present invention discloses a rotor coreless multi-disk axial flux permanent magnet motor and operating method, comprising: an upper stator, an upper coreless rotor, a middle stator, a lower coreless rotor, and a lower stator, arranged in sequence; stator core teeth are provided at both the upper and lower ends of the middle stator core yoke, and stator core teeth are provided at the ends of the upper and lower stators proximate to the middle stator; the upper or lower coreless rotor comprises: a plurality of tilting permanent magnets arranged circumferentially and evenly spaced along the circumferential plane of the rotor, and a rotor disk fixing frame. By designing a tilting permanent magnet and stator stator offset structure, combined with an operating method of differential phase excitation of the upper and lower windings, the present invention enables the cogging torques of the two rotor disks to be superimposed at peaks and troughs, respectively, thereby reducing the total cogging torque and torque ripple.

Description

Technical Field

[0001] The present invention relates to the technical field of axial flux permanent magnet motors, and in particular to a rotor coreless multi-disk axial flux permanent magnet motor and a working method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the rapid development of industries such as aerospace, shipbuilding, and new energy vehicles, the performance and quality requirements for motors are becoming increasingly higher. Compared with traditional radial flux motors, axial flux motors have the advantages of compact structure and high torque density, making them gradually suitable for new application scenarios such as electric motorcycles, airport pods, cargo trucks, and electric vehicles. However, for axial flux motors with a single stator and single rotor structure, the increase in motor torque is accompanied by an increase in motor diameter, and the limitation of installation space often affects its application. The multi-disc axial flux motor solves this problem, and by stacking multiple stator disks and rotor disks in the axial direction, it further increases the output power of the motor, while also reducing the rated current of the motor and improving the motor efficiency.

[0004] However, traditional multi-disc axial flux motors, with multiple stator and rotor discs stacked axially, create a complex magnetic field between the discs. The superposition of torque peaks and valleys causes significant cogging torque and torque ripple, which degrades torque output quality, increases vibration and noise, and significantly impacts motor performance. Current approaches primarily aim to reduce cogging torque and torque ripple by optimizing slot width and pole-slot ratio, but this reduces average torque. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a rotor coreless multi-disk axial flux permanent magnet motor and a working method. Through the design of the tilting permanent magnet and stator staggered structure, combined with the working method of differential excitation of the upper and lower winding phases, the slot torques of the two rotor disks can be superimposed at the peaks and troughs respectively, thereby reducing the total slot torque and torque fluctuation.

[0006] In some embodiments, the following technical solutions are adopted:

[0007] A rotor coreless multi-disk axial flux permanent magnet motor, comprising: an upper stator, an upper coreless rotor, a middle stator, a lower coreless rotor, and a lower stator, which are arranged in sequence; the upper coreless rotor and the lower coreless rotor are both fixed relative to the output shaft in the axial direction;

[0008] Stator core teeth are provided at both upper and lower ends of the middle stator core yoke, and the stator core teeth at the upper and lower ends of the middle stator core yoke are staggered; stator core teeth are provided at one end of the upper stator and the lower stator close to the middle stator; axial magnetic flux concentrated windings are wound around the stator core teeth;

[0009] The upper coreless rotor or the lower coreless rotor comprises: a plurality of tilting permanent magnets uniformly arranged along the circumferential direction, the tilting permanent magnets being uniformly and evenly spaced along the circumferential plane of the rotor, the gaps between the tilting permanent magnets being filled with a fixing agent to form a rotor hollow disk; the rotor hollow disk being disposed within a rotor disk fixing frame;

[0010] The upper and lower surfaces of each tilting permanent magnet in the axial direction are both sectors surrounded by two straight lines and two concentric arcs. The sectors of the upper and lower surfaces are the same size and shape and are staggered in the circumferential direction; the centers of the two concentric arcs of all sectors are on the central axis of the rotor disk.

[0011] The tilting directions of the tilting permanent magnets on the same coreless rotor are the same, and the tilting directions of the tilting permanent magnets on different coreless rotors are opposite.

[0012] The staggered angle between the upper and lower fan-shaped straight lines of the tilting permanent magnet in the axial direction is 0.8θ≤γ≤1.2θ, where θ is the staggered angle between the upper and lower stator teeth of the middle stator.

[0013] As an optional solution, at the initial moment of movement, the alignment angle of the stator core teeth at the upper end of the middle stator core yoke and the fan-shaped lower surface in the axial direction of the tilting permanent magnet of the upper coreless rotor is exactly the same as the alignment angle of the stator core teeth at the lower end of the middle stator core yoke and the fan-shaped upper surface in the axial direction of the tilting permanent magnet of the lower coreless rotor.

[0014] As an optional solution, the tilting permanent magnets on the upper coreless rotor or the lower coreless rotor are magnetized in the axial direction, and the magnetization directions of two adjacent tilting permanent magnets on the same coreless rotor are opposite.

[0015] As an optional solution, the rotor disk fixing frame includes two oppositely arranged hollow disks made of non-magnetic material, which are fixedly connected by multiple parallel fixing bars; the two hollow disks are hollowed out at the upper and lower surfaces of each tilting permanent magnet in the axial direction.

[0016] As an optional solution, the stator core teeth at the upper end of the middle stator core yoke are aligned with the stator core teeth of the upper stator core yoke; the stator core teeth at the lower end of the middle stator core yoke are aligned with the stator core teeth of the lower stator core yoke.

[0017] As an optional solution, a group of axial flux concentrated windings are respectively wound around the stator core teeth at the upper and lower ends of the middle stator core yoke, the stator core teeth of the upper stator, and the stator core teeth of the lower stator.

[0018] In other embodiments, the following technical solutions are adopted:

[0019] A method for operating a rotor coreless multi-disk axial flux permanent magnet motor, comprising:

[0020] The axial flux winding of the upper stator and the axial flux winding at the upper end of the middle stator are respectively excited with the same phase α, and the generated first magnetic field acts on the upper coreless rotor, which can make the upper coreless rotor rotate;

[0021] The same phase β excitation is applied to the axial flux winding at the lower end of the middle stator and the axial flux winding at the lower stator, respectively, to generate a second magnetic field that acts on the lower coreless rotor, thereby causing the lower coreless rotor to rotate. The stator teeth at the upper and lower ends of the middle stator are offset by a setting angle θ, so that the phase difference between the phase α and the phase β is p / 2*θ, where p is the number of poles of the motor rotor, thereby forming an integral through-magnetic circuit, reducing magnetic field coupling consumption, and generating a more concentrated magnetic field, thereby driving the upper and lower coreless rotors to rotate synchronously.

[0022] When a single-stator disk and single-rotor disk axial flux permanent magnet motor has p poles and s slots, the fundamental wave of the torque fluctuation has s*p / GCD(s, p) cycles per rotor rotation, where GCD(s, p) represents the greatest common divisor of s and p. When the stator core teeth at the upper end and the stator core teeth at the lower end of the stator core yoke are offset by an angle θ=360° / [s*p / GCD(s, p)], the torque and cogging torque of the upper coreless rotor and the lower coreless rotor are superimposed at the peaks and troughs, respectively, to reduce the total cogging torque.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) In the present invention, both the upper coreless rotor and the lower coreless rotor are provided with tilting permanent magnets, and the upper and lower surfaces of the tilting permanent magnets along the axial direction have the same shape and are staggered. Combined with the staggered arrangement of the stator core teeth, the cogging torques on the upper and lower surfaces of the two rotor disks of the multi-disk axial flux permanent magnet motor with three stators and two coreless rotors can be superimposed at the peaks and troughs respectively, thereby reducing the fluctuation of the total cogging torque.

[0025] (2) In the present invention, the stator core teeth at the upper end of the stator core yoke are aligned with the stator core teeth of the upper stator core yoke; the two sets of axial flux windings wound on these two stator core teeth act on the upper coreless rotor at the same time, and the two sets of axial flux windings are excited in the same phase, which can effectively reduce the problem of large axial unbalanced tension on the rotor disk of the single-disk axial flux motor; similarly, the stator core teeth at the lower end of the middle stator core yoke are aligned with the stator core teeth of the lower stator core yoke, which can also reduce the axial unbalanced tension on the lower coreless rotor.

[0026] In addition, the tilting permanent magnets of the upper coreless rotor and the lower coreless rotor tilt in opposite directions, further reducing the axial unbalanced pull on the two coreless rotors, thereby further reducing bearing wear and increasing bearing service life; at the same time, the magnets with opposite tilting directions are symmetrical along the middle plane of the central stator, which also reduces the unbalanced axial pull on the central stator.

[0027] (3) The coreless rotor structure of the present invention eliminates the rotor core of the traditional structure, eliminates the eddy current loss and hysteresis loss generated by the rotor core, reduces energy loss, improves heat dissipation performance, and improves efficiency. The coreless rotor structure reduces the thickness of the core, reduces the axial length of the rotor, and reduces the weight and volume, making the overall structure of the motor more compact and more convenient to install and use in special spaces. The coreless rotor has a smaller inertia after eliminating the metal material, and can quickly respond to changing load requirements. Epoxy resin is an insulating material and does not generate a magnetic field inside. The tilting permanent magnets in the coreless rotor can generate a more concentrated magnetic field, and the motor of the same volume can achieve a higher torque output.

[0028] Other features and advantages of additional aspects of the present invention will be given in part in the following description and in part will become obvious from the following description or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of a rotor coreless multi-disk axial flux permanent magnet motor according to an embodiment of the present invention;

[0030] 2(a)-(b) are respectively a half-sectional view and a three-dimensional view of an exploded schematic diagram of the overall structure of a rotor coreless multi-disk axial flux permanent magnet motor according to an embodiment of the present invention;

[0031] 3(a)-(b) are respectively a half-sectional view and a three-dimensional view of a schematic diagram of a stator core tooth misalignment structure in a rotor coreless multi-disk axial flux permanent magnet motor according to an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of the coreless rotor structure in an embodiment of the present invention;

[0033] Figure 51. This is an axial schematic diagram of a coreless rotor according to an embodiment of the present invention;

[0034] Figure 6 Schematic diagram of the rotor disk fixing frame structure in an embodiment of the present invention;

[0035] Figure 7 Schematic diagram of the overall structure of the rotor disk fixing frame and the rotor disk in an embodiment of the present invention;

[0036] Figure 8 A comparison diagram of the cogging torque of the upper and lower coreless rotors, as well as the total cogging torque, during no-load simulation of a coreless rotor multi-disk axial flux permanent magnet motor according to an embodiment of the present invention;

[0037] Figure 9 1. The torque of the upper coreless rotor and the lower coreless rotor, as well as the total torque comparison diagram during load simulation of the coreless rotor multi-disk axial flux permanent magnet motor according to an embodiment of the present invention;

[0038] Among them, 1-1. Upper stator, 1-2. Middle stator, 1-3. Lower stator, 2-1. Upper coreless rotor, 2-2. Lower coreless rotor, 3. Stator core, 4. Three-phase concentrated winding, 5. Tilting permanent magnet, 6. Epoxy resin fixative, 7. Rotor disk fixing frame. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0041] Example 1

[0042] In one or more embodiments, a rotor coreless multi-disk axial flux permanent magnet motor is disclosed, combined with Figure 1 2(a)-(b), specifically comprising: an upper stator 1-1, an upper coreless rotor 2-1, a middle stator 1-2, a lower coreless rotor 2-2 and a lower stator 1-3 arranged in sequence from top to bottom.

[0043] 3(a)-(b), the stator core 3 includes a cylindrical core yoke and stator teeth. The thickness of the core yoke of the middle stator 1-2 is twice the thickness of the core yoke of the upper stator 1-1 or the lower stator 1-3. Both the upper stator 1-1 and the lower stator 1-3 are single-sided core stator teeth. The middle stator 1-2 core yoke has stator teeth at both ends, and the stator teeth at the upper and lower ends are staggered. The stator teeth of the upper stator 1-1 are aligned with the stator teeth at the upper end of the core yoke of the middle stator 1-2, and the stator teeth of the lower stator 1-3 are aligned with the stator teeth at the lower end of the core yoke of the middle stator 1-2.

[0044] Axial flux windings are wound on the stator teeth. In this embodiment, there are four groups of axial flux windings. One group of windings is wound on each of the stator teeth of the upper stator 1-1 and the lower stator 1-3, and one group of windings is wound on each of the stator teeth at the upper and lower ends of the middle stator 1-2.

[0045] In this embodiment, the stator teeth and windings of the upper stator 1-1 and the stator teeth and windings at the upper end of the middle stator 1-2 simultaneously act on the upper coreless rotor 2-1, and both sets of windings are excited in phase. This effectively reduces the axial unbalanced pull of the upper coreless rotor 2-1, thus avoiding the high axial unbalanced pull experienced by current single-disc axial flux motor rotors. Similarly, the stator teeth and windings of the lower stator 1-3 and the stator teeth and windings at the lower end of the middle stator 1-2 primarily act on the lower coreless rotor 2-2, and both sets of windings are excited in phase, also effectively reducing the axial unbalanced pull of the lower coreless rotor 2-2.

[0046] Combine Figure 4 and Figure 5 In this embodiment, the upper coreless rotor 2-1 includes: a plurality of tilting permanent magnets 5 uniformly arranged along the circumferential direction. The tilting permanent magnets 5 are arranged at uniform intervals along the center of the rotor circumferential plane. The gaps between the tilting permanent magnets 5 are filled with an ironless rotor epoxy resin fixative 6. The tilting permanent magnets 5 and the epoxy resin fixative 6 together form a hollow disk. The rotor hollow disk formed by the tilting permanent magnets and the fixative is disposed within a rotor disk fixing frame 7. The upper coreless rotor 2-1 and the lower coreless rotor 2-2 are axially fixed relative to the output shaft, so that the upper coreless rotor 2-1 and the lower coreless rotor 2-2 rotate synchronously.

[0047] In this embodiment, the upper and lower surfaces of each tilting permanent magnet 5 in the axial direction are identical and planarly geometrically symmetrical sectors surrounded by two straight lines and two concentric arcs. The upper and lower surfaces are geometrically symmetrical but staggered in the circumferential direction. Figure 5As shown, the upper surface is represented by a solid line, and the lower surface is represented by a dotted line. The straight line edges of the sectors on the upper surface of the tilting permanent magnet 5 are offset from the straight line edges of the corresponding sectors on the lower surface by a mechanical angle of 0.8θ≤γ≤1.2θ. In this embodiment, θ=10° (mechanical angle) and γ is 9° (mechanical angle). The centers of all sectors are on the central axis of the hollow disk, and the centers of all sectors on the upper surface and all sectors on the lower surface are the same.

[0048] While conventional sector-shaped permanent magnets have a rectangular circumferential cross-section, the tilting permanent magnets 5 of this embodiment are not two-dimensional, nor do they have an arc-shaped inner or outer diameter. Instead, they have an oblique cross-section that tilts circumferentially. The tilting permanent magnets 5 exhibit an overall tilted sector-shaped shape, evenly spaced along the rotor's circumference. All tilting permanent magnets 5 on the same rotor have the same tilt angle and offset angle.

[0049] In this embodiment, the structure of the lower coreless rotor 2-2 is basically the same as that of the upper coreless rotor 2-1, except that the tilting angles of the tilting permanent magnets 5 in the lower coreless rotor 2-2 are the same, but opposite to the tilting angles of the tilting permanent magnets 5 in the upper coreless rotor 2-1, that is, the tilting directions of the tilting permanent magnets 5 on the same coreless rotor are the same, while the tilting directions of the tilting permanent magnets 5 on different coreless rotors are opposite.

[0050] The tilting permanent magnets 5 of the lower coreless rotor 2-2 are arranged in mirror-symmetric fashion with the tilting permanent magnets 5 of the upper coreless rotor 2-1. All rotor tilting permanent magnets 5 are magnetized axially. In the same coreless rotor, adjacent tilting permanent magnets 5 are magnetized in opposite directions.

[0051] In this embodiment, the axial flux windings on the upper stator teeth of the upper stator 1-1 and the middle stator 1-2 form a pole-slot match with the tilting permanent magnets 5 on the upper coreless rotor 2-1; the axial flux windings on the lower stator teeth of the lower stator 1-3 and the middle stator 1-2 form a pole-slot match with the tilting permanent magnets 5 on the lower coreless rotor 2-2.

[0052] In this embodiment, the arrangement of the tilting permanent magnets 5 in the upper coreless rotor 2-1 and the lower coreless rotor 2-2, combined with the stator teeth and windings corresponding to the upper coreless rotor 2-1 and the stator teeth and windings corresponding to the lower coreless rotor 2-2, results in the staggered upper and lower sector-shaped cross-sections of the tilting permanent magnets 5 achieving the effect of rotor skew. While the upper and lower sector-shaped cross-sections of the same coreless rotor are staggered, the windings acting on them are aligned, so that the cogging torque applied to the upper and / or lower end faces of a single rotor is superimposed at peaks and troughs, thereby achieving a reduced cogging torque. The teeth of the upper and lower stators 1-3 of the middle stator are staggered by 10 degrees (mechanical angle), and the first and second sets of windings and the third and fourth sets of windings applied to the two coreless rotors are 30 degrees out of phase. This allows the torque and cogging torque between the two rotor disks of the three-stator and dual-coreless rotor multi-disc axial flux permanent magnet motor to be superimposed at peaks and troughs, respectively, thereby further reducing the total cogging torque fluctuation.

[0053] At the same time, the tilting permanent magnets 5 on the upper and lower coreless rotors tilt in opposite directions. The upper and lower coreless rotors 2-1 and 2-2 are axially fixed relative to the output shaft. At the initial moment of movement, the alignment angle between the stator core teeth at the upper end of the middle stator core yoke and the lower sector-shaped plane of the tilting permanent magnets of the upper coreless rotor 2-1 is exactly the same as the alignment angle between the stator core teeth at the lower end of the middle stator core yoke and the upper sector-shaped plane of the tilting permanent magnets of the lower coreless rotor 2-2. This further reduces the axial unbalanced tension on the two coaxial rotors, thereby reducing bearing wear and increasing bearing service life. Furthermore, the symmetry of the magnets, tilted in opposite directions, along the midplane of the middle stator 1-2 also reduces the unbalanced axial tension on the stators 1-2 during operation.

[0054] Combine Figure 6 and Figure 7 In this embodiment, the upper and lower coreless rotors are respectively arranged in a rotor disk fixing frame 7 for fixing. The rotor disk fixing frame 7 includes: two hollow disks made of non-magnetic material with upper and lower hollow holes and parallel fixing bars. The upper and lower hollow disk-shaped fixing plates of the rotor disk fixing frame 7 are hollowed out on the fan-shaped surface in the axial direction of each tilting permanent magnet. The coreless rotor is arranged between the two hollow fixing plates; a plurality of parallel fixing bars are provided on the circumferential outer side of the hollow disk-shaped structure of the rotor disk fixing frame. The parallel fixing bars can fix the upper and lower hollow disks of non-magnetic material together, and at the same time confine the hollow disk-shaped structure formed by the tilting permanent magnet 5 and the epoxy resin fixing agent 6 within the rotor disk fixing frame.

[0055] The coreless rotor of this embodiment is composed of tilting permanent magnets 5, an epoxy resin fixative, and a rotor disk fixing frame. The gaps between the tilting permanent magnets are filled with a fixative to form a hollow rotor disk. The rotor disk fixing frame is composed of two pieces of non-magnetic material with hollowed-out top and bottom sections. The hollow rotor disk formed by the tilting permanent magnets and the fixative is disposed within the rotor disk fixing frame. The upper coreless rotor 2-1 and the lower coreless rotor 2-2 are axially fixed relative to the output shaft. The coreless rotor structure eliminates the rotor core of the traditional structure, eliminating the eddy current loss and hysteresis loss generated by the rotor core, reducing energy loss, improving heat dissipation performance, and improving efficiency. The coreless rotor structure reduces the core thickness, the axial length of the rotor, and its weight and volume, making the overall structure of the motor more compact and more convenient to install and use in special spaces. The coreless rotor has a smaller inertia after eliminating the metal material and can quickly respond to changing load requirements. Epoxy resin is an insulating material and does not generate a magnetic field inside. The tilting permanent magnet 5 in the coreless rotor can generate a more concentrated magnetic field, and the motor of the same volume can achieve a higher torque output.

[0056] The coreless rotor multi-disk axial flux permanent magnet motor of this embodiment adopts a 9-slot, 6-pole configuration, making motor winding and manufacturing relatively easy. The stator disks of the axial flux motor form a suitable pole-slot match with the axial flux tilting permanent magnets 5. Appropriate excitation is applied to the upper stator winding 1-1 and the middle stator upper winding, generating a magnetic field that primarily acts on the upper coreless rotor 2-1, driving the upper coreless rotor 2-1 to rotate. Similarly, appropriate excitation is applied to the lower stator winding 1-3 and the lower stator winding 1-3, generating a magnetic field that primarily acts on the lower coreless rotor 2-2, driving the lower coreless rotor 2-2 to rotate. The teeth of the upper and lower stators 1-3 of the middle stator are offset by θ = 10° (mechanical angle). The wound windings are excited by three-phase current, with three pairs of poles. The excitation offset angle is the product of the mechanical angle and the number of pole pairs. Therefore, the phase difference between phase α and phase β is p / 2*θ = 30°, which is more conducive to forming an integrated through-magnetic circuit and reducing magnetic field coupling loss. The four sets of windings in the three stators and the double coreless rotors form the overall magnetic circuit of the multi-disc motor, reducing the magnetic field coupling consumption between the four sets of windings and the magnets, generating a more concentrated magnetic field, thereby driving the upper coreless rotor 2-1 and the lower coreless rotor 2-2 to perform synchronous rotation.

[0057] The stator tooth windings of the upper stator 1-1 are flush with the stator tooth windings at the upper end of the middle stator 1-2, and are excited with the same phase α. The stator tooth windings at the lower end of the middle stator 1-2 are flush with the stator tooth windings of the lower stator 1-3, and are offset by a mechanical angle of 10° from the stator teeth at the upper end of the middle stator 1-2, and are excited with the same phase β. The teeth of the upper and lower stators 1-3 of the middle stator are offset by 10° (mechanical angle), and the wound windings are excited by three-phase current. The windings have three pairs of poles, and the excitation offset angle is the product of the mechanical angle and the number of pole pairs. Therefore, the phase difference between phase α and phase β is 30°, which is more conducive to forming an overall through-magnetic circuit and reducing magnetic field coupling consumption.

[0058] When a single-stator-disc, single-rotor axial flux permanent magnet motor has p poles and s slots and rotates at n rpm, the fundamental torque fluctuation per rotor revolution has s*p / GCD(s, p) cycles (GCD(s, p) is the greatest common divisor of s and p). The stator teeth at the upper end of the middle stator 1-2 and the stator teeth at the lower end of the middle stator 1-2 are offset by θ = 360° / [s*p / GCD(s, p)]. This allows the torque and cogging torque of the upper and lower rotor discs to superimpose at peaks and troughs, respectively, achieving optimal superposition. This further reduces the total cogging torque, improving the motor's output quality and operational safety, stability, and reliability. The motor is powered by four sets of windings, one for each stator tooth at the upper and lower ends of the middle stator 1-2. The middle stator core yoke is twice as thick as the core yokes of the upper and lower stators 1-3, improving heat dissipation from the middle stator disc.

[0059] Figure 8 1 is a comparison diagram of the cogging torque of the upper coreless rotor 2-1 and the lower coreless rotor 2-2, as well as the total cogging torque during no-load simulation of the coreless rotor multi-disk axial flux permanent magnet motor in this embodiment; Figure 9 The figure shows the torque of the upper coreless rotor 2-1 and the lower coreless rotor 2-2 during motor load simulation, as well as a comparison diagram of the total torque. It can be seen that the torque and cogging torque of the upper coreless rotor 2-1 and the lower coreless rotor 2-2 are superimposed at the peak and trough respectively, thereby further reducing the total cogging torque and torque pulsation of the coaxial upper and lower coreless rotors, and improving the quality of motor output and the safety, stability and reliability of operation.

[0060] This embodiment employs a control scheme using four sets of three-phase concentrated windings 4. All in-phase windings can be powered in series or in parallel. In this embodiment, the three-phase windings within the same set of four three-phase concentrated windings 4 have an electrical angle difference of 120°. The stator teeth of the upper stator 1-1 corresponding to the upper rotor are aligned with the stator teeth of the upper stator 1-1 of the middle stator 1-2. The first and second sets of windings wound thereon are excited with the same phase. The teeth of the lower stator 1-3 of the middle stator 1-2 corresponding to the lower rotor are aligned with the stator teeth of the lower stator 1-3. The third and fourth sets of windings wound thereon are excited with the same phase, with a 30° delay in phase from the first and second sets of windings. For a 6-pole, 9-slot motor as an example, the axial mechanical offset of the windings wound around the stator teeth 1-1, from bottom to top, is 0°, 10°, and 0°. The phase differences in the excitation of the stator windings, from bottom to top, are 0°, 30°, and 0°, respectively.

[0061] At the initial moment of movement, the alignment angle between the stator core teeth at the upper end of the middle stator core yoke and the lower fan-shaped plane in the axial direction of the tilting permanent magnet of the upper coreless rotor 2-1 is exactly the same as the alignment angle between the stator core teeth at the lower end of the middle stator core yoke and the upper fan-shaped plane in the axial direction of the tilting permanent magnet of the lower coreless rotor 2-2. The upper coreless rotor 2-1 and the lower coreless rotor 2-2 are relatively fixed to the output shaft in the axial direction, so that the upper coreless rotor 2-1 and the lower coreless rotor 2-2 rotate synchronously.

[0062] The coreless rotor multi-disk axial flux permanent magnet motor of this embodiment can improve the power density and reduce the volume of the motor under the same output power; the coreless rotor structure can reduce the eddy current loss and hysteresis loss in the rotor core in the traditional structure, has smaller inertia and lighter mass, can quickly respond to changing load requirements, has a more concentrated magnetic field, can achieve higher torque output, has a shorter axial length, and a more compact overall structure, which helps to further realize the miniaturization of the equipment.

[0063] The structure of multiple stator disks can increase the heat dissipation area. Under the joint action of two stator disks, the axial unbalanced magnetic pull of each coreless rotor is greatly reduced, thereby reducing the wear of the bearings. The stator offset and tilting permanent magnet 5 structure of the present application and the corresponding control method respectively superimpose the torque and cogging torque of the two coaxial rotors at the peak and trough, thereby achieving a reduction in the overall output cogging torque and torque pulsation, reducing vibration and noise, and improving the quality of the motor torque output and the safety, stability and reliability of operation.

[0064] Example 2

[0065] In one or more embodiments, a method for operating a rotor coreless multi-disk axial flux permanent magnet motor is disclosed, specifically comprising the following steps:

[0066] The axial flux winding of the upper stator 1-1 and the axial flux winding at the upper end of the middle stator 1-2 are respectively excited with the same phase α, and the generated first magnetic field acts on the upper coreless rotor 2-1, which can make the upper coreless rotor 2-1 rotate;

[0067] The axial flux winding at the lower end of the middle stator 1-2 and the axial flux winding of the lower stator 1-3 are respectively excited with the same phase β, and the generated second magnetic field acts on the lower coreless rotor 2-2; the lower coreless rotor 2-2 can be made to rotate; the teeth of the upper and lower stators 1-3 of the middle stator are offset by θ=10° (mechanical angle), and the wound windings are excited by three-phase current. The windings have three pairs of poles in total, and the excitation offset angle is the product of the mechanical angle and the number of pole pairs. Therefore, the phase difference between the phase α and the phase β is p / 2*θ=30°, which is more conducive to forming an overall through-magnetic circuit and reducing the magnetic field coupling consumption.

[0068] The upper coreless rotor 2-1 and the lower coreless rotor 2-2 are relatively fixed to the output shaft in the axial direction. The first magnetic field and the second magnetic field interact with each other to generate a more concentrated magnetic field, thereby driving the upper coreless rotor 2-1 and the lower coreless rotor 2-2 to perform synchronous rotation.

[0069] In this embodiment, when the stator core teeth at the upper end and the stator core teeth at the lower end of the middle stator core yoke are offset by θ=360° / [s*p / GCD(s, p)], the torque and cogging torque of the upper coreless rotor 2-1 and the lower coreless rotor 2-2 are superimposed at the peak and trough respectively, and the best effect can be achieved, thereby realizing the reduction of cogging torque and torque fluctuation.

[0070] Among them, when the single-stator disk and single-rotor disk axial flux permanent magnet motor has p poles and s slots, the fundamental wave of the torque fluctuation has s*p / GCD(s, p) cycles per rotor rotation, and GCD(s, p) represents the greatest common divisor of s and p.

[0071] By calculating the misalignment angle, the cogging torque and torque fluctuation of the coaxial twin coreless rotors are superimposed with peaks and troughs to achieve the reduction of the cogging torque and torque fluctuation.

[0072] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A rotor coreless multi-disk axial flux permanent magnet motor, characterized in that: include: An upper stator, an upper coreless rotor, a middle stator, a lower coreless rotor and a lower stator are sequentially arranged; the upper coreless rotor and the lower coreless rotor are both relatively fixed to the output shaft in the axial direction; Stator core teeth are provided at both upper and lower ends of the middle stator core yoke, and the stator core teeth at the upper and lower ends of the middle stator core yoke are staggered; stator core teeth are provided at one end of the upper stator and the lower stator close to the middle stator; axial magnetic flux concentrated windings are wound around the stator core teeth; The upper coreless rotor or the lower coreless rotor comprises: a plurality of tilting permanent magnets uniformly arranged along the circumferential direction, the tilting permanent magnets being uniformly and evenly spaced along the circumferential plane of the rotor, the gaps between the tilting permanent magnets being filled with a fixing agent to form a rotor hollow disk; the rotor hollow disk being disposed within a rotor disk fixing frame; The upper and lower surfaces of each tilting permanent magnet in the axial direction are both sectors surrounded by two straight lines and two concentric arcs. The sectors of the upper and lower surfaces are identical in size and shape and are staggered in the circumferential direction. The centers of the two concentric arcs of all sectors are on the central axis of the rotor disk. The staggered angle between the upper and lower fan-shaped straight lines of the tilting permanent magnet in the axial direction is 0.8θ≤γ≤1.2θ, where θ is the staggered angle between the upper and lower stator teeth of the middle stator.

2. The rotor coreless multi-disk axial flux permanent magnet motor according to claim 1, characterized in that: The tilting directions of the tilting permanent magnets on the same coreless rotor are the same, and the tilting directions of the tilting permanent magnets on different coreless rotors are opposite.

3. The rotor coreless multi-disk axial flux permanent magnet motor according to claim 1, characterized in that: At the initial moment of movement, the alignment angle between the stator core teeth at the upper end of the middle stator core yoke and the fan-shaped lower surface in the axial direction of the tilting permanent magnet of the upper coreless rotor is exactly the same as the alignment angle between the stator core teeth at the lower end of the middle stator core yoke and the fan-shaped upper surface in the axial direction of the tilting permanent magnet of the lower coreless rotor.

4. The rotor coreless multi-disk axial flux permanent magnet motor according to claim 1, characterized in that: The tilting permanent magnets on the upper coreless rotor or the lower coreless rotor are magnetized in the axial direction, and the magnetization directions of two adjacent tilting permanent magnets on the same coreless rotor are opposite.

5. The rotor coreless multi-disk axial flux permanent magnet motor according to claim 1, characterized in that: The rotor disk fixing frame includes two oppositely arranged hollow disks made of non-magnetic material, which are fixedly connected by multiple parallel fixing bars; the two hollow disks are hollowed out at the upper and lower surfaces of each tilting permanent magnet in the axial direction.

6. The rotor coreless multi-disk axial flux permanent magnet motor according to claim 1, characterized in that: The stator core teeth at the upper end of the middle stator core yoke are aligned with the stator core teeth of the upper stator core yoke; the stator core teeth at the lower end of the middle stator core yoke are aligned with the stator core teeth of the lower stator core yoke.

7. The rotor coreless multi-disk axial flux permanent magnet motor according to claim 1, characterized in that: A set of axial magnetic flux concentrated windings are respectively wound around the stator core teeth at the upper and lower ends of the middle stator core yoke, the stator core teeth of the upper stator and the stator core teeth of the lower stator.

8. The operating method of the rotor coreless multi-disk axial flux permanent magnet motor according to any one of claims 1 to 7, characterized in that: include: The axial flux winding of the upper stator and the axial flux winding at the upper end of the middle stator are respectively excited with the same phase α, and the generated first magnetic field acts on the upper coreless rotor, which can make the upper coreless rotor rotate; The same phase β excitation is applied to the axial flux winding at the lower end of the middle stator and the axial flux winding at the lower stator, respectively, to generate a second magnetic field that acts on the lower coreless rotor, thereby causing the lower coreless rotor to rotate. The stator teeth at the upper and lower ends of the middle stator are offset by a setting angle θ, so that the phase difference between the phase α and the phase β is p / 2*θ, where p is the number of poles of the motor rotor, thereby forming an integral through-magnetic circuit, reducing magnetic field coupling consumption, and generating a more concentrated magnetic field, thereby driving the upper and lower coreless rotors to rotate synchronously.

9. The operating method of the coreless rotor multi-disk axial flux permanent magnet motor according to claim 8, characterized in that: When a single-stator disk and single-rotor disk axial flux permanent magnet motor has p poles and s slots, the fundamental wave of the torque fluctuation has s*p / GCD(s, p) cycles per rotor rotation, where GCD(s, p) represents the greatest common divisor of s and p. When the stator core teeth at the upper end and the stator core teeth at the lower end of the stator core yoke are offset by an angle θ=360° / [s*p / GCD(s, p)], the torque and cogging torque of the upper coreless rotor and the lower coreless rotor are superimposed at the peaks and troughs, respectively, to reduce the total cogging torque.

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