Axial flux motor based on double-rotor and single-stator alternation

Abstract

One or more embodiments of the invention relate to the technical field of permanent magnet motors, in particular to an axial magnetic flux motor based on double-rotor and single-stator alternation, which comprises a stator structure, an upper rotor structure and a lower rotor structure, and the lower rotor structure, the stator structure and the upper rotor structure are stacked in sequence. The distances to the upper rotor structure and the lower rotor structure are equal; the stator structure comprises a stator core and armature windings, stator teeth are uniformly arranged on the two sides, close to the lower rotor structure and the upper rotor structure, of the annular side face of the stator core at intervals in the circumferential direction, stator grooves are formed between the adjacent stator teeth, and the armature windings are embedded in the stator grooves; the upper rotor structure and the lower rotor structure are the same and are symmetrical relative to the central plane of the stator structure, the upper rotor structure and / or the lower rotor structure comprises a rotor iron core, permanent magnets and modulation teeth, and the permanent magnets and the modulation teeth are alternately arranged in the rotor iron core in the circumferential direction. Under the condition that the number of the permanent magnets is small, the output torque is improved, and the torque pulsation is small.

Description

Technical Field

[0001] One or more embodiments of the present specification relate to the technical field of permanent magnet motors, and in particular, to an axial flux motor based on alternating dual rotors and a single stator. Background Art

[0002] The axial flux motor has attracted attention for its high power density, high torque density, light weight, compact design and high efficiency. It can provide high power and torque output in a small volume and has excellent cooling performance. These advantages make the axial flux motor have great potential in advanced applications such as electric vehicles, aerospace, and high-performance industrial equipment. The dual-rotor single-stator axial flux motor is a motor with two rotors and one stator installed in the motor. The axial pull generated by the two rotors on the middle stator offsets each other, which can eliminate unilateral magnetic pull, reduce the load on the bearing, and reduce vibration and noise. And the dual-rotor structure has a higher overall air gap flux density than the single-rotor structure, thereby reducing the total amount of permanent magnets.

[0003] When designing a motor, it is necessary to consider improving the utilization rate of permanent magnets and reducing the cost of the motor. However, the research and design methods for improving the utilization rate of permanent magnets in axial flux motors are still insufficient. The method of using an alternating pole structure in the prior art improves the utilization rate of permanent magnets, but at the same time it will cause the output torque of the motor to be reduced and the torque pulsation to be greatly increased, affecting the overall performance of the motor.

[0004] Although the axial flux motor with an alternating pole structure can reduce the use of permanent magnets, more in-depth research is still needed to improve the output torque and suppress torque pulsation. In summary, the present application now proposes an axial flux motor based on a dual-rotor single-stator alternating structure to solve the above-mentioned problems. Summary of the invention

[0005] The present invention aims to solve the problems raised in the background technology. This specification discloses an axial flux motor based on alternating dual rotors and a single stator, which can improve the utilization rate of permanent magnets, increase the output torque, and suppress torque pulsation.

[0006] Based on the above purpose, one or more embodiments of the present specification provide an axial flux motor based on double rotor and single stator alternation, comprising a stator structure, an upper rotor structure and a lower rotor structure, wherein the lower rotor structure, the stator structure and the upper rotor structure are stacked in sequence, and the distances to the upper rotor structure and the lower rotor structure are equal;

[0007] The stator structure comprises a stator core and an armature winding, stator teeth are evenly spaced along the circumferential direction on both sides of the annular side surface of the stator core close to the lower rotor structure and close to the upper rotor structure, stator slots are formed between adjacent stator teeth, and the armature windings are embedded in the stator slots;

[0008] The upper rotor structure is identical to the lower rotor structure and is symmetrical with respect to the central plane of the stator structure. The upper rotor structure and / or the lower rotor structure comprises a rotor core, permanent magnets and modulation teeth. Permanent magnets and modulation teeth are alternately arranged circumferentially inside the rotor core.

[0009] According to the axial flux motor based on double rotor and single stator alternation proposed in an embodiment of the present invention, the permanent magnets and the modulation teeth are of the same sector-shaped structure, and the number of the permanent magnets and the number of the modulation teeth are equal.

[0010] According to the axial flux motor based on alternating dual rotors and a single stator proposed in an embodiment of the present invention, the permanent magnets are arranged circumferentially at positions that are staggered by a magnetic pole angle on the upper rotor structure and the lower rotor structure.

[0011] According to the axial flux motor based on double rotor and single stator alternation proposed in an embodiment of the present invention, the pole arc coefficient of the permanent magnet and the pole arc coefficient of the modulation tooth satisfy the following relationship: α p =α m =1.

[0012] According to the axial flux motor based on alternating dual rotors and single stators proposed in an embodiment of the present invention, the permanent magnet includes a main pole, a first auxiliary pole and a second auxiliary pole, the main pole is in an "I" shape, and the first auxiliary pole and the second auxiliary pole are symmetrically distributed on both sides of the main pole.

[0013] According to the axial flux motor based on double rotor and single stator alternation proposed in the embodiment of the present invention, the pole arc coefficient of the main magnetic pole is α p1 , the pole arc coefficients of the first auxiliary magnetic pole and the second auxiliary magnetic pole are both α p2 , and satisfy the following relationship: p =α p1 +2α p2 =1; the radial length of the first auxiliary magnetic pole and the second auxiliary magnetic pole is T pm1 The outer radial length and inner radial length of the main magnetic pole after being divided by the first auxiliary magnetic pole and the second auxiliary magnetic pole are both T pm2 ;

[0014] Among them, α p1 :α p2 =1-9:1, T pm1 :T pm2 =1-15:1.

[0015] According to the axial flux motor based on alternating dual rotors and a single stator proposed in an embodiment of the present invention, the magnetization direction of the main magnetic pole is axially pointing to the stator structure, and the magnetization directions of the first auxiliary magnetic pole and the second auxiliary magnetic pole are both oblique to the magnetization direction of the main magnetic pole, forming an angle θ with the magnetization direction of the main magnetic pole and axially pointing to the stator structure; wherein θ=45°-80°.

[0016] According to the dual-rotor single-stator alternating axial flux motor proposed in an embodiment of the present invention, the stator core, the rotor core and the modulation teeth are all made of silicon steel material.

[0017] According to the dual-rotor single-stator alternating axial flux motor proposed in an embodiment of the present invention, the permanent magnet material is neodymium iron boron, samarium cobalt or ferrite.

[0018] According to the axial flux motor based on double-rotor single-stator alternation proposed in an embodiment of the present invention, the armature winding is arranged in an integer-slot concentrated winding structure.

[0019] According to the above, the present invention has the following beneficial effects:

[0020] 1. The present invention adopts a dual-rotor single-stator structure. The HALBACH structure can enhance the useful magnetic flux density close to the stator side and weaken the useless magnetic flux density close to the rotor core side, thereby improving the overall air gap magnetic flux density, which is beneficial to improving the power density of the motor and reducing the amount of permanent magnets used.

[0021] 2. The present invention adopts an alternating pole structure in a dual-rotor single-stator axial flux motor, and optimizes the design of the amount of permanent magnets used in the upper rotor structure and the lower rotor structure, thereby further reducing the amount of permanent magnets used.

[0022] 3. The present invention utilizes the characteristic that the dual-rotor motor has two rotor structures, and the upper rotor structure and the lower rotor structure are staggered in polarity, thereby reducing the high torque pulsation of the alternating-pole structure motor.

[0023] 4. The new "I"-shaped HALBACH permanent magnet structure adopted by the present invention has more adjustable parameters and a wider optimization range compared with the traditional three-segment HALBACH permanent magnet structure. It can increase the air gap flux density and the output torque, thus making up for the shortcoming of the decreased output torque of the alternating pole structure motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate one or more embodiments of the present specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only one or more embodiments of the present specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A three-dimensional structural diagram of a specific embodiment of the present invention;

[0026] Figure 2It is a three-dimensional structure explosion diagram of this embodiment;

[0027] Figure 3 is a comparison diagram of the upper rotor structure and the lower rotor structure of this embodiment;

[0028] Figure 4 Schematic diagram of the HALBACH permanent magnet of this embodiment;

[0029] Figure 5 The air gap magnetic density diagram of the motor with staggered poles and no HALBACH structure in this embodiment;

[0030] Figure 6 Air gap magnetic flux density diagram of staggered-pole HALBACH structure of the motor in this embodiment;

[0031] Figure 7 This is a comparison diagram of the output torque of the motor of this embodiment using a non-staggered pole and non-HALBACH structure and a staggered pole and non-HALBACH structure;

[0032] Figure 8 This is a comparison diagram of the output torque of the motor of this embodiment using a staggered-pole non-HALBACH structure and a staggered-pole HALBACH structure;

[0033] Reference numerals:

[0034] 10. Stator structure; 11. Stator core; 12. Stator slots; 13. Stator teeth; 14. Armature winding;

[0035] 20. upper rotor structure; 21. rotor core; 22. HALBACH structure; 23. modulation teeth; 221. main magnetic pole; 222. first auxiliary magnetic pole; 223. second auxiliary magnetic pole;

[0036] 30. Lower rotor structure. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments.

[0038] like Figure 1 and Figure 2 As shown, an embodiment of the present invention proposes an axial flux motor based on double rotor and single stator alternation, characterized in that it comprises a stator structure, an upper rotor structure and a lower rotor structure, wherein the lower rotor structure, the stator structure and the upper rotor structure are stacked in sequence, and the distances to the upper rotor structure and the lower rotor structure are equal;

[0039] The stator structure includes a stator core and an armature winding. Stator teeth are evenly spaced along the circumferential direction on both sides of the annular side surface of the stator core close to the lower rotor structure and the upper rotor structure. Stator slots are formed between adjacent stator teeth. Armature windings are embedded in the stator slots. Current in the same direction is passed through the armature windings in symmetrical upper and lower slots. As a preferred embodiment, the number of stator slots on the upper and lower sides of the stator core is both, and the number of stator teeth is both 45.

[0040] The upper rotor structure is identical to the lower rotor structure and is symmetrical relative to the central plane of the stator structure. The upper rotor structure and / or the lower rotor structure include a rotor core, permanent magnets and modulation teeth. Permanent magnets and modulation teeth are alternately arranged circumferentially inside the rotor core. The permanent magnets are HALBACH permanent magnets. The permanent magnets and modulation teeth adopt a fan-shaped structure of the same size, and the outer diameter of the fan-shaped structure is smaller than the outer diameter of the rotor core, and the inner diameter of the fan-shaped structure is larger than the inner diameter of the rotor core. The number of permanent magnets and modulation teeth is equal, and the permanent magnets and modulation teeth form an alternating pole structure. As a preferred embodiment, the number of permanent magnet poles of the upper rotor structure and the lower rotor structure are both 5, and the number of modulation teeth are both 5.

[0041] like Figure 3 As shown in the figure, the permanent magnets are arranged at circumferential positions of the upper rotor structure and the lower rotor structure at a staggered magnetic pole angle to form a staggered pole structure. The pole arc coefficient α of the permanent magnets p and the pole arc coefficient α of the modulated tooth m Satisfies the following relationship: p =α m =1, that is, in the upper rotor structure, “permanent magnet—modulation tooth—permanent magnet—modulation tooth—permanent magnet—modulation tooth—permanent magnet—modulation tooth—permanent magnet—modulation tooth” are arranged to form a circle, while in the lower rotor structure, “modulation tooth—permanent magnet—modulation tooth—permanent magnet—modulation tooth—permanent magnet—modulation tooth—permanent magnet” are arranged to form a circle.

[0042] The permanent magnet includes a main magnetic pole, a first auxiliary magnetic pole and a second auxiliary magnetic pole. The main magnetic pole is in the shape of an "I". The boundary lines of the main magnetic pole, the first auxiliary magnetic pole and the second auxiliary magnetic pole along the radial direction point to the same center of a circle. The first auxiliary magnetic pole and the second auxiliary magnetic pole are symmetrically distributed on both sides of the main magnetic pole.

[0043] like Figure 4 As shown, the pole arc coefficient of the main magnetic pole is α p1 , the pole arc coefficients of the first auxiliary magnetic pole and the second auxiliary magnetic pole are both α p2 , and satisfy the following relationship: p =α p1 +2α p2 =1. The radial length of the first auxiliary magnetic pole and the second auxiliary magnetic pole is T pm1The outer radial length and inner radial length of the main magnetic pole after being divided by the first auxiliary magnetic pole and the second auxiliary magnetic pole are both T pm2 Among them, α p1 :α p2 =1-9:1, T pm1 :T pm2 =1-15:1.

[0044] like Figure 4 As shown, the magnetization direction of the main magnetic pole is axially pointing to the stator structure, and the magnetization directions of the first auxiliary magnetic pole and the second auxiliary magnetic pole are oblique to the magnetization direction of the main magnetic pole, and form an angle θ with the magnetization direction of the main magnetic pole and axially point to the stator structure. In a specific embodiment, regardless of the upper rotor structure or the lower rotor structure, the magnetization direction of the main magnetic pole in the permanent magnet is axially pointing to the stator structure. Wherein, θ = 45°-80°.

[0045] As a preferred solution, the stator core, rotor core and modulation teeth are all made of silicon steel. The permanent magnet material can be, but is not limited to, neodymium iron boron, samarium cobalt, ferrite, etc. The armature winding is arranged in an integer slot concentrated winding structure.

[0046] like Figure 5 and Figure 6 The figure is an air gap flux density diagram of the staggered-pole non-HALBACH structure and the staggered-pole HALBACH structure of the example motor of the present invention. Under the condition of the same amount of permanent magnets, the average value of the absolute value of the air gap flux density of the staggered-pole non-HALBACH structure is 0.78T, and the air gap flux density waveform fluctuates greatly; the average value of the absolute value of the air gap flux density of the staggered-pole HALBACH structure is 0.85T, which is 8.9% higher than that of the staggered-pole non-HALBACH structure, and the air gap flux density waveform is more sinusoidal, indicating that the staggered-pole HALBACH structure is beneficial to improving the output torque of the motor.

[0047] like Figure 7 The output torque comparison diagram of the motor of this embodiment using a non-staggered pole and non-HALBACH structure is shown in FIG. The torque pulsation of the output torque of the non-staggered pole and non-HALBACH structure is 30.8%, and the torque pulsation of the output torque of the staggered pole and non-HALBACH structure is 19.2%, and the torque pulsation is reduced by 37.7%, indicating that the staggered pole structure is conducive to the smooth operation of the motor.

[0048] like Figure 8The output torque comparison chart of the motor of this embodiment using a staggered-pole non-HALBACH structure and a staggered-pole HALBACH structure. The average output torque of the staggered-pole non-HALBACH structure is 116.3Nm, and the average output torque of the staggered-pole HALBACH structure is 121.7Nm. Compared with the staggered-pole non-HALBACH structure, the output torque of the staggered-pole HALBACH structure is increased by 5.4Nm, with an increase of 4.6%, while the amount of permanent magnets remains unchanged. The torque pulsation of the two is similar, indicating that the staggered-pole HALBACH structure has a higher permanent magnet utilization rate.

[0049] The present invention provides a dual-rotor single-stator alternating-pole staggered-pole HALBACH structure axial flux motor. Compared with the traditional axial flux motor, the amount of permanent magnets used can be reduced by about 28% while ensuring similar output torque, which is beneficial to reducing the cost of the motor. The staggered-pole HALBACH structure is used to reduce the high torque pulsation caused by the alternating-pole structure, compensating for the deficiency of the alternating-pole structure causing a decrease in output torque.

[0050] One or more embodiments of this specification are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of this disclosure.

Claims

1. An axial flux motor based on double rotor and single stator alternation, characterized in that: It comprises a stator structure, an upper rotor structure and a lower rotor structure, wherein the lower rotor structure, the stator structure and the upper rotor structure are stacked in sequence and are equidistant from the upper rotor structure and the lower rotor structure; The stator structure comprises a stator core and an armature winding, stator teeth are evenly spaced along the circumferential direction on both sides of the annular side surface of the stator core close to the lower rotor structure and close to the upper rotor structure, stator slots are formed between adjacent stator teeth, and the armature windings are embedded in the stator slots; The upper rotor structure is identical to the lower rotor structure and is symmetrical with respect to the central plane of the stator structure. The upper rotor structure and / or the lower rotor structure comprises a rotor core, permanent magnets and modulation teeth. Permanent magnets and modulation teeth are alternately arranged circumferentially inside the rotor core.

2. The axial flux motor based on double rotor and single stator alternation according to claim 1 is characterized in that: The permanent magnets and the modulation teeth are of the same sector-shaped structure, and the number of the permanent magnets and the number of the modulation teeth are equal.

3. The axial flux motor based on double rotor and single stator alternation according to claim 1 is characterized in that: The permanent magnets are arranged at circumferential positions of the upper rotor structure and the lower rotor structure at a staggered magnetic pole angle.

4. The axial flux motor based on double rotor and single stator alternation according to claim 3 is characterized in that: The pole arc coefficient of the permanent magnet and the pole arc coefficient of the modulation tooth satisfy the following relationship: α p =α m =1.

5. The axial flux motor based on double rotor and single stator alternation according to claim 1, characterized in that: The permanent magnet includes a main magnetic pole, a first auxiliary magnetic pole and a second auxiliary magnetic pole. The main magnetic pole is in an "I" shape, and the first auxiliary magnetic pole and the second auxiliary magnetic pole are symmetrically distributed on both sides of the main magnetic pole.

6. The axial flux motor based on double rotor and single stator alternation according to claim 5 is characterized in that: The pole arc coefficient of the main magnetic pole is α p1 , the pole arc coefficients of the first auxiliary magnetic pole and the second auxiliary magnetic pole are both α p2 , and satisfy the following relationship: α p =α p1 +2α p2 =1; the radial length of the first auxiliary magnetic pole and the second auxiliary magnetic pole is T pm1 The outer radial length and inner radial length of the main magnetic pole after being divided by the first auxiliary magnetic pole and the second auxiliary magnetic pole are both T pm2 ; Among them, a p1 :a p2 =1-9:1,T pm1 :T pm2 =1-15:

1.

7. The axial flux motor based on double rotor and single stator alternation according to claim 5 is characterized in that: The magnetization direction of the main magnetic pole is axially pointing to the stator structure, and the magnetization directions of the first auxiliary magnetic pole and the second auxiliary magnetic pole are both oblique to the magnetization direction of the main magnetic pole, forming an angle θ with the magnetization direction of the main magnetic pole and axially pointing to the stator structure; wherein θ=45°-80°.

8. The axial flux motor based on double rotor and single stator alternation according to claim 1 is characterized in that: The stator iron core, the rotor iron core and the modulation teeth are all made of silicon steel material.

9. The axial flux motor based on double rotor and single stator alternation according to claim 1, characterized in that: The permanent magnet material is neodymium iron boron, samarium cobalt or ferrite.

10. The axial flux motor based on double rotor and single stator alternation according to claim 1, characterized in that: The armature winding is arranged in an integer slot concentrated winding structure.

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