Split tooth type magnetic field modulation axial magnetic flux composite motor and working method thereof

Abstract

The invention relates to a split tooth type magnetic field modulation axial magnetic flux composite motor and a working method thereof, and belongs to the technical field of permanent magnet motors. The motor comprises a casing, a rotating shaft, a mixed stator, a low-speed rotor and a high-speed rotor, the mixed stator is fixed on the casing, the low-speed rotor and the high-speed rotor are symmetrically arranged on two sides of the mixed stator and sleeve the rotating shaft, and two ends of the rotating shaft are respectively fixed on the casing through bearing frames. High-speed and low-speed direct drive transmission with a large speed ratio can be achieved in the same radial space, and the problems that in the prior art, reliability is poor, efficiency is low and torque density is low are solved.

Description

Technical Field

[0001] The invention relates to a split-tooth magnetic field modulation axial magnetic flux composite motor and a working method thereof, belonging to the technical field of permanent magnet motors. Background Art

[0002] In fields such as transportation, industrial automation, medical equipment, home appliances, and consumer electronics, motors are often required to frequently switch speeds and maintain high speed ratios. For example, in a household washing machine, the speed typically ranges from 50-120 rpm in wash mode to 800-1600 rpm in spin mode, with a maximum speed ratio of 32:1. These high speed ratios and frequent switching requirements also require the motor to be quiet, efficient, and have a high torque density.

[0003] To meet these requirements, dual-speed motors offer a solution. By designing two sets of windings, they balance performance at two speeds, switching between them based on actual operating conditions. However, dual-speed motors only support two fixed speeds, lacking stepless speed regulation and struggling to adapt to dynamic load fluctuations. Currently, two commonly used solutions are permanent magnet brushless DC (BLDC) motors with external belt drives and direct-drive motors. While both offer stepless speed regulation, they also present numerous challenges that need to be addressed. The former often uses an external belt drive, resulting in transmission losses, high maintenance costs, and poor reliability. The latter, directly connected to the load, eliminates transmission losses, but its large speed ratio prevents the motor from maintaining high efficiency across the entire speed range. Furthermore, low-speed designs result in a larger motor diameter and bulk, and torque density needs to be further improved.

[0004] Disc motors offer core advantages such as compact axial space, high torque density, and fast dynamic response, making them commonly used in space-constrained applications requiring high dynamic performance. Compared to the several motor solutions mentioned above, disc motors are smaller, more compact, and offer higher torque density. Furthermore, their disc-shaped structure facilitates multi-pole design and direct connection to the load, making them ideal for low-speed, high-torque direct-drive applications. Similarly, disc motors can only achieve high speed ratio outputs through the motor's own speed regulation, and cannot maintain high efficiency across the entire speed range.

[0005] The problems with the above motor solution are summarized as follows: 1. There is an intermediate transmission link, and the transmission loss makes the overall efficiency of the system low. In addition, the transmission device often has a high failure rate, high maintenance cost and low reliability.

[0006] 2. The high-efficiency zone of a permanent magnet motor generally exists near the rated point. For motor applications with a large speed ratio, it is impossible to maintain high efficiency under both high-speed and low-speed conditions.

[0007] 3. When permanent magnet motors are designed for low speed, the number of pole pairs is large, the motor outer diameter and axial dimensions are large, and the torque density is not high.

[0008] There is currently no good solution to the above problems. Summary of the Invention

[0009] In response to the shortcomings of the existing technology, the present invention provides a split-tooth magnetic field modulation axial flux composite motor, which can achieve high-speed and low-speed direct drive transmission with a large speed ratio in the same radial space, so as to overcome the problems of poor reliability, low efficiency and low torque density in the existing technology.

[0010] The present invention also provides a method for operating the above-mentioned split-tooth magnetic field modulation axial magnetic flux composite motor.

[0011] The technical solutions of the present invention are as follows: A split-tooth magnetic field modulation axial magnetic flux composite motor includes a casing, a rotating shaft, a hybrid stator, a low-speed rotor and a high-speed rotor. The hybrid stator is fixed to the casing. The low-speed rotor and the high-speed rotor are symmetrically arranged on both sides of the hybrid stator. The low-speed rotor and the high-speed rotor are sleeved on the rotating shaft. The two ends of the rotating shaft are fixed to the casing through bearing frames.

[0012] According to a preferred embodiment of the present invention, the hybrid stator includes a stator yoke, spur teeth, and modulated teeth. A plurality of spur teeth and modulated teeth are symmetrically arranged around each side of the stator yoke, and annular windings are provided on the spur teeth and modulated teeth. Bolts are used to rigidly connect the hybrid stator to the housing to prevent axial movement of the hybrid stator and maintain a uniform air gap.

[0013] According to a further preferred embodiment of the present invention, the modulation teeth include main teeth and split teeth. The main teeth are fixed to the stator yoke and provided with an annular winding. A plurality of split teeth are provided on top of the main teeth. The split teeth are all of the same size and arranged circumferentially. The number of split teeth on a single main tooth is an odd number. The use of split teeth to divide a single tooth into multiple smaller teeth changes the geometric structure of the magnetic circuit, causing the magnetic permeance to exhibit periodic variations in space, adjusting the magnetic permeance distribution and magnetic field harmonics, and achieving active modulation of the air gap magnetic field. Straight teeth have no magnetic modulation effect, while split teeth do have a magnetic field modulation effect.

[0014] Preferably, according to the present invention, the stator yoke, spur teeth and modulation teeth are all made of high-performance silicon steel sheets made of magnetic conductive material.

[0015] According to the present invention, the toroidal windings are preferably wound with pure copper wire. A toroidal winding is provided for each of the spur teeth and the modulating teeth. The two sets of toroidal windings are independent of each other. Three-phase alternating current is supplied to the corresponding windings according to actual operating conditions to generate a rotating magnetic field. The toroidal windings utilize a concentrated winding method, which shortens the end winding length, reduces copper loss, and improves efficiency.

[0016] Preferably, according to the present invention, the low-speed rotor includes a low-speed magnet and a low-speed rotor disk. A plurality of low-speed magnets are arranged on one side of the low-speed rotor disk. The low-speed magnets are opposite to the modulation teeth to form a low-speed unit motor. The gap between the low-speed magnet and the modulation teeth is the first air gap.

[0017] Preferably, according to the present invention, the high-speed rotor includes high-speed magnets and a high-speed rotor disk. A plurality of high-speed magnets are arranged on one side of the high-speed rotor disk. The high-speed magnets are fan-shaped. The high-speed magnets are opposite to the straight teeth to form a high-speed unit motor. The gap between the high-speed magnets and the straight teeth is the second air gap.

[0018] According to the preferred embodiment of the present invention, the number of pole pairs of the low-speed magnetic steel is greater than that of the high-speed magnetic steel. An N-pole magnetic steel and an S-pole magnetic steel form a pair of poles. If the number of high-speed magnetic steels is n h , then its pole pair number is n h / 2, from n=60*f / p, we get that the magnets with fewer pole pairs are arranged on the high-speed rotor disk and perform high-speed motion, and the magnets with more pole pairs are arranged on the low-speed rotor disk and perform low-speed motion. n is the speed, f is the frequency, and p is the number of pole pairs. Under the premise of unchanged frequency, the larger the number of pole pairs, the smaller the speed, and the size of the low-speed magnet is smaller than that of the high-speed magnet.

[0019] The magnetizing directions of the low-speed magnetic steel and the high-speed magnetic steel are opposite to each other along the axial direction.

[0020] The operating method of the above-mentioned split-tooth magnetic field modulation axial flux composite motor comprises the following steps: (1) When outputting at high speed, current is passed through the annular winding on the spur teeth, and the high-speed magnet and the high-speed rotor disk generate a rotor rotating magnetic field. The number of magnetic field pole pairs is the same as the number of stator rotating magnetic field pole pairs generated by the annular winding on the spur teeth, and high-speed output is performed externally; (2) At low speed output, current flows into the annular winding on the modulation tooth, generating a pole pair number p L The stator rotating magnetic field is passed through N t The split teeth change the magnetic circuit structure and magnetic field distribution, and the p L The magnetic field with a pole pair number of N is modulated to t -p L The low-speed magnetic field, at this time, the modulated magnetic field and N L The number of magnetic field pole pairs generated by the low-speed magnets matches that of N L / 2=N t -p L The winding generates a high-speed rotating magnetic field with a low pole pair number. The high-speed rotating magnetic field with a low pole pair number is modulated by the magnetic field modulation of the modulation teeth and modulated into a low-speed magnetic field with a high pole pair number. It interacts with the low-speed magnetic field with a high pole pair number generated by the low-speed rotor and outputs a low-speed and high torque to the outside.

[0021] The beneficial effects of the present invention are: 1. The low-speed unit motor of the present invention utilizes the principle of magnetic field modulation to construct a set of magnetic gear devices, which converts the high-speed rotating magnetic field into a low-speed rotor magnetic field, thereby achieving low-speed and high-torque output to the outside, ensuring that the high-speed unit motor and the low-speed unit motor can maintain uniform radial dimensions.

[0022] 2. The present invention can flexibly switch between high-speed unit motors and low-speed unit motors according to actual working conditions, ensuring that the motors operate near the high-efficiency rated point in both low-speed and high-speed states.

[0023] 3. The composite motor of the present invention does not require an external transmission device, thereby improving the reliability and efficiency of the entire system and reducing subsequent maintenance costs.

[0024] 4. The high-speed unit motor and the low-speed unit motor of the present invention work independently without affecting each other, and share the middle stator yoke, which saves axial space and does not cause magnetic circuit coupling.

[0025] 5. The present invention can flexibly design the number of split teeth according to the actual speed ratio to meet the requirements of the magnetic gear transmission ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a three-dimensional schematic diagram of the present invention.

[0027] Figure 2 It is an explosion diagram of the present invention.

[0028] Figure 3 Schematic diagram of the hybrid stator structure of the present invention.

[0029] Figure 4 It is a schematic diagram of the high-speed rotor structure of the present invention.

[0030] Figure 5 It is a schematic diagram of the low-speed rotor structure of the present invention.

[0031] Figure 6 Schematic diagram of the structure of a single annular winding of the present invention.

[0032] Figure 7 It is a straight line expansion diagram of the present invention.

[0033] Figure 8 This is a principle diagram of the magnetic field modulation effect of the present invention.

[0034] Figure 9 This is the Fourier decomposition diagram of the air gap magnetic flux under the load condition of the present invention.

[0035] Reference numerals: 1. Hybrid stator; 2. Low-speed rotor; 3. High-speed rotor; 11. Stator yoke; 12. Straight teeth; 13. Main teeth; 14. Split teeth; 15. Ring winding; 21. Low-speed magnetic steel; 22. Low-speed rotor disc; 31. High-speed magnetic steel; 32. High-speed rotor disk; 41. First air gap; 42. Second air gap. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to embodiments and accompanying drawings, but is not limited thereto.

[0037] Example 1: like Figure 1-Figure 7 As shown, this embodiment provides a split-tooth magnetic field modulation axial flux composite motor, including a casing, a rotating shaft, a hybrid stator 1, a low-speed rotor 2 and a high-speed rotor 3. The hybrid stator 1 is fixed to the casing, and the low-speed rotor 2 and the high-speed rotor 3 are symmetrically arranged on both sides of the hybrid stator 1. The low-speed rotor 2 and the high-speed rotor 3 are mounted on the rotating shaft, and both ends of the rotating shaft are fixed to the casing through bearing frames.

[0038] The hybrid stator 1 comprises a stator yoke 11, spur teeth 12, and modulating teeth. Several spur teeth 12 and modulating teeth are symmetrically arranged around the stator yoke 11, each with an annular winding 15. Bolts rigidly connect the hybrid stator 1 to the housing, preventing axial movement and maintaining a uniform air gap.

[0039] The modulation teeth include main teeth 13 and split teeth 14. The main teeth 13 are fixed to the stator yoke 11 and are provided with an annular winding 15. Several split teeth 14 are provided on top of the main teeth 13. Each split tooth 14 is of the same size and arranged circumferentially. The number of split teeth 14 on a single main tooth 13 is an odd number. The split teeth 14 are used to divide a single tooth into multiple small teeth, changing the geometric structure of the magnetic circuit. This causes the magnetic permeance to exhibit periodic variations in space, adjusts the magnetic permeance distribution and magnetic field harmonics, and achieves active modulation of the air gap magnetic field. The spur teeth 12 have no magnetic modulation effect, while the split teeth 14 have a magnetic field modulation effect. Both the spur teeth 12 and the modulation teeth are stator teeth. Adjacent stator teeth form stator slots, and the number of stator slots is a multiple of 3.

[0040] The number of main teeth 13 is Q. A single main tooth 13 is provided with a split teeth 14, forming a-1 small grooves and N t The total number of split teeth, Q*a=N t .

[0041] The stator yoke 11, the spur teeth 12 and the modulation teeth are all made of high-performance silicon steel sheets made of magnetic conductive material.

[0042] The toroidal winding 15 is wound by pure copper wire. The structure of a single toroidal winding 15 is as follows: Figure 6As shown, they are arranged circumferentially on both sides of the hybrid stator 1. In this embodiment, a concentrated winding form is adopted, and a single annular winding is only wound on a single tooth. There is no overlapping part between the annular windings, and the end portions extend shorter, saving copper wire and improving efficiency. The circumferential arrangement of the annular winding is not limited to concentrated windings, but is also applicable to distributed windings.

[0043] The low-speed rotor 2 includes a low-speed magnetic steel 21 and a low-speed rotor disk 22. One side of the low-speed rotor disk 22 is provided with an N L The low-speed magnetic steel 21 is opposite to the modulation teeth to form a low-speed unit motor. The gap between the low-speed magnetic steel 21 and the modulation teeth is the first air gap 41. The number of pole pairs of the stator rotating magnetic field of the low-speed unit motor is p. L Satisfy p L +N L / 2=Q*a, N L An even number.

[0044] In this embodiment, the number of pole pairs of the stator rotating magnetic field of the low-speed unit motor is p L 3, the number of low-speed magnetic steel is N L is 84, the number of main teeth Q is 9, and the number of split teeth a on a single main tooth is 5, satisfying the relationship 3+84 / 2=9*5.

[0045] The high-speed rotor 3 includes a high-speed magnetic steel 31 and a high-speed rotor disk 32. One side of the high-speed rotor disk 32 is provided with an N H High-speed magnets 31, N with opposite polarity H The high-speed magnetic steels 31 are arranged in a circumferential direction in sequence. The high-speed magnetic steels 31 are fan-shaped. The high-speed magnetic steels 31 are opposite to the straight teeth 12 to form a high-speed unit motor. The number of stator magnetic field pole pairs of the high-speed end unit motor is N. H / 2,N H The gap between the high-speed magnet and the straight teeth is the second air gap. Since the high-speed magnet 31 has a small number of pole pairs and a large magnet volume, in order to effectively suppress the eddy current loss of the magnet and reduce the risk of heating and demagnetization, the high-speed magnet 31 is segmented in the circumferential direction, such as Figure 4 As shown, the high-speed magnetic steel 31 is divided into three sections.

[0046] The number of pole pairs of the low-speed magnetic steel 21 is greater than that of the high-speed magnetic steel 31. An N-pole magnetic steel and an S-pole magnetic steel form a pair of poles. If the number of high-speed magnetic steels is n h , then its pole pair number is n h / 2, from n=60*f / p, it can be obtained that the magnets with fewer pole pairs are arranged on the high-speed rotor disk and perform high-speed motion, and the magnets with more pole pairs are arranged on the low-speed rotor disk and perform low-speed motion. n is the speed, f is the frequency, and p is the number of pole pairs. Under the premise of unchanged frequency, the larger the number of pole pairs, the smaller the speed. The size of the low-speed magnet 21 is smaller than that of the high-speed magnet 31.

[0047] The magnetizing directions of the low-speed magnetic steel 21 and the high-speed magnetic steel 31 are opposite to each other along the axial direction.

[0048] The straight line expansion diagram of this embodiment is as follows Figure 7 As shown, when the low-speed unit motor is working, the magnetic excitation line passes through the low-speed magnetic steel 21-first air gap 41-split tooth 14-main tooth 13-stator yoke 11-main tooth 13-split tooth 14-first air gap 41-low-speed magnetic steel 21-low-speed rotor disk 22 to form a closed loop; when the high-speed unit motor is working, the magnetic excitation line passes through the high-speed magnetic steel 31-second air gap 42-straight tooth 12-stator yoke 11-straight tooth 12-second air gap 42-high-speed magnetic steel 31-high-speed rotor disk 32 to form a closed loop. The two share a set of stator yoke 11, which greatly reduces the axial size and improves the torque density.

[0049] The principle of the magnetic field modulation effect of the present invention is as follows Figure 8 As shown, the number of pole pairs of the magnetic field at the low-speed end is 42. After the modulation of 45 split teeth, a high-speed magnetic field with a pole pair number of 3 is generated in the first air gap. The speed of the low-speed rotor 2 is very slow, but under the magnetic modulation of the split teeth 14, the slower speed can generate a rotating magnetic field with a very high speed on the stator side. It is under the action of this magnetic field modulation effect that the high-speed unit motor and the low-speed unit motor can be combined into a composite motor with the same radial size to achieve switching between different output modes.

[0050] The operating method of the above-mentioned split-tooth magnetic field modulation axial flux composite motor comprises the following steps: (1) During high-speed output, current is passed through the annular winding 15 on the spur teeth 12, and the high-speed magnet 31 and the high-speed rotor disk 32 generate a rotor rotating magnetic field. The number of magnetic field pole pairs is the same as the number of stator rotating magnetic field pole pairs generated by the annular winding 15 on the spur teeth, and high-speed output is performed externally; (2) At low speed output, current is passed through the annular winding 15 on the modulation tooth, generating a pole pair number p L The stator rotating magnetic field is passed through N t The split teeth change the magnetic circuit structure and magnetic field distribution, and the p L The magnetic field with a pole pair number of N is modulated to t -p L The low-speed magnetic field, at this time, the modulated magnetic field and N L The number of magnetic field pole pairs generated by the low-speed magnets matches that of N L / 2=N t -p L The winding generates a high-speed rotating magnetic field with a low pole pair number. The high-speed rotating magnetic field with a low pole pair number is modulated by the magnetic field modulation of the modulation teeth and modulated into a low-speed magnetic field with a high pole pair number. It interacts with the low-speed magnetic field with a high pole pair number generated by the low-speed rotor 2 and outputs a low-speed and high-torque to the outside.

[0051] The composite motor is simulated based on the three-dimensional finite element analysis method, and the magnetic field modulation principle of the modulation side unit motor is simulated. The Fourier decomposition results of the air gap magnetic flux under load conditions are as follows: Figure 9 As shown: the harmonic is mainly 42 times, that is, the fundamental magnetic field of 42 pairs of poles, indicating that the air gap magnetic field is a 42-pole magnetic field. In addition, there are a small amount of 3rd harmonics. It can be seen that the 3-pole high-speed stator rotating magnetic field is modulated into a 42-pole low-speed rotating magnetic field under the magnetic modulation of 45 modulation teeth. The number of pole pairs of this magnetic field is the same as that of the rotating magnetic field generated by the low-speed magnetic steel. According to k=N L / p L The interaction between the two ultimately achieves a low-speed, high-torque output effect with a transmission ratio of 14, making the compound motor have two output states: high-speed and low-speed, high-torque.

Claims

1. A split-tooth magnetic field modulation axial flux composite motor, characterized in that: It includes a casing, a rotating shaft, a hybrid stator, a low-speed rotor and a high-speed rotor. The hybrid stator is fixed to the casing. The low-speed rotor and the high-speed rotor are symmetrically arranged on both sides of the hybrid stator. The low-speed rotor and the high-speed rotor are sleeved on the rotating shaft. The two ends of the rotating shaft are fixed to the casing through bearing frames.

2. The split-tooth magnetic field modulation axial flux composite motor according to claim 1, characterized in that: The hybrid stator includes a stator yoke, spur teeth and modulating teeth. A number of spur teeth and modulating teeth are symmetrically arranged on both sides of the stator yoke, and annular windings are arranged on the spur teeth and modulating teeth.

3. The split-tooth magnetic field modulation axial flux composite motor according to claim 2, characterized in that: The modulation teeth include main teeth and split teeth. The main teeth are fixed to the stator yoke. An annular winding is provided on the main teeth. Several split teeth are provided on the top of the main teeth. The split teeth are the same size and arranged along the circumferential direction. The number of split teeth on a single main tooth is an odd number.

4. The split-tooth magnetic field modulation axial flux composite motor according to claim 3, characterized in that: The stator yoke, spur teeth and modulation teeth are all made of high-performance silicon steel sheets made of magnetic conductive material.

5. The split-tooth magnetic field modulation axial flux composite motor according to claim 2, characterized in that: The toroidal winding is made of pure copper wire.

6. The split-tooth magnetic field modulation axial flux composite motor according to claim 3, characterized in that: The low-speed rotor includes a low-speed magnet and a low-speed rotor disk. A plurality of low-speed magnets are arranged on one side of the low-speed rotor disk. The low-speed magnets are opposite to the modulation teeth to form a low-speed unit motor. The gap between the low-speed magnet and the modulation teeth is the first air gap.

7. The split-tooth magnetic field modulation axial flux composite motor according to claim 6, characterized in that: The high-speed rotor includes high-speed magnets and a high-speed rotor disk. Several high-speed magnets are arranged on one side of the high-speed rotor disk. The high-speed magnets are fan-shaped and opposite to the spur teeth to form a high-speed unit motor. The gap between the high-speed magnets and the spur teeth is the second air gap.

8. The split-tooth magnetic field modulation axial flux composite motor according to claim 7, characterized in that: The number of pole pairs of the low-speed magnet is greater than that of the high-speed magnet, and the size of the low-speed magnet is smaller than that of the high-speed magnet.

9. The operating method of the split-tooth magnetic field modulation axial flux composite motor according to claim 8, characterized in that: Here are the steps: (1) When outputting at high speed, current is passed through the annular winding on the spur teeth, and the high-speed magnet and the high-speed rotor disk generate a rotor rotating magnetic field. The number of magnetic field pole pairs is the same as the number of stator rotating magnetic field pole pairs generated by the annular winding on the spur teeth, and high-speed output is performed externally; (2) At low speed output, current flows into the annular winding on the modulation tooth, generating a pole pair number p L The stator rotating magnetic field is passed through N t The split teeth change the magnetic circuit structure and magnetic field distribution, and the p L The magnetic field with a pole pair number of N is modulated to t -p L The low-speed magnetic field, at this time, the modulated magnetic field and N L The number of magnetic field pole pairs generated by the low-speed magnets matches that of N L / 2=N t -p L The winding generates a high-speed rotating magnetic field with a low pole pair number. The high-speed rotating magnetic field with a low pole pair number is modulated by the magnetic field modulation of the modulation teeth and modulated into a low-speed magnetic field with a high pole pair number. It interacts with the low-speed magnetic field with a high pole pair number generated by the low-speed rotor and outputs a low-speed and high torque to the outside.

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