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

Abstract

The application relates to a split-tooth magnetic field modulation axial flux composite motor and a working method thereof, and belongs to the technical field of permanent magnet motors. The motor comprises a machine shell, a rotating shaft, a hybrid stator, a low-speed rotor and a high-speed rotor. The hybrid stator is fixed to the machine shell. The low-speed rotor and the high-speed rotor are symmetrically arranged on the two sides of the hybrid stator. The low-speed rotor and the high-speed rotor are sleeved on the rotating shaft. The rotating shaft is fixed to the machine shell through a bearing frame at both ends. The motor can realize 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 prior art.

Description

TECHNICAL FIELD

[0001] The application relates to a split tooth type magnetic field modulation axial flux composite motor and a working method thereof, and belongs to the technical field of permanent magnet motors. BACKGROUND

[0002] In the fields of transportation, industrial automation, medical equipment, home appliances and consumer electronics, it is often required that the motor frequently switches the speed ratio and the speed ratio is very large. Taking a household washing machine as an example, the speed is generally 50-120 rpm in the washing mode, and the speed is generally 800-1600 rpm in the dehydration mode, and the maximum speed ratio can reach 32:1. The speed ratio is large and needs to be frequently switched. In addition, the motor is required to be small in noise, high in efficiency and high in torque density.

[0003] To meet the above requirements, a double-speed motor is one of the solutions, which can meet the performance at two speeds by designing two sets of windings and switching according to the actual working condition. However, the double-speed motor only supports two fixed speeds and cannot realize stepless speed regulation, which is difficult to match the dynamic change of the load. At present, the permanent magnet brushless direct current motor (BLDC) is usually used in two schemes of external belt transmission and direct drive motor. Both of them can realize stepless speed regulation, but there are still many problems to be solved. Among them, the former is usually connected with a belt transmission link, which has transmission loss and high maintenance cost, and poor reliability. The latter is directly connected with the load, and there is no transmission loss, but the large speed ratio makes the motor unable to maintain high efficiency in the whole speed range. In addition, the motor has a large outer diameter when designed at low speed, and the motor has a large volume and the torque density needs to be further improved.

[0004] The disc type motor has the core advantages of compact axial space, high torque density and fast dynamic response, and is often used in scenes with limited space and high dynamic performance. Compared with the above-mentioned motor schemes, the disc type motor has smaller volume, compact structure and higher torque density. In addition, the disc type structure is more suitable for multi-pole design and direct connection with the load, and is very suitable for low-speed and high-torque direct drive application occasions. Similarly, the disc type motor can only meet the large speed ratio output through the speed regulation of the motor itself, and cannot maintain high efficiency in the whole speed range.

[0005] The problems of the above motor schemes are summarized as follows:

[0006] 1. There is an intermediate transmission link, and the transmission loss makes the overall system efficiency low, and the transmission device often has a high failure rate, high maintenance cost and low reliability.

[0007] 2. The high efficiency area of the permanent magnet motor generally exists near the rated point. For the motor application with a large speed ratio, it is difficult to maintain high efficiency at high speed and low speed.

[0008] 3. When the permanent magnet motor is designed at low speed, the pole pair number is large, the motor outer diameter and axial dimension are large, and the torque density is not high.

[0009] In view of the above problems, there is no good solution at present. SUMMARY

[0010] In view of the deficiencies of the prior art, the application provides a split-tooth magnetic field modulation axial flux composite motor, which can realize 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 prior art.

[0011] The application also provides a working method of the split-tooth magnetic field modulation axial flux composite motor.

[0012] The technical scheme of the application is as follows:

[0013] A split-tooth magnetic field modulation axial flux composite motor comprises 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, and the rotating shaft is fixed to the casing through a bearing frame at both ends.

[0014] According to the application, the hybrid stator comprises a stator yoke, straight teeth and modulation teeth, a plurality of straight teeth and modulation teeth are symmetrically arranged on both sides of the stator yoke, and annular windings are arranged on the straight teeth and the modulation teeth. The hybrid stator and the casing are rigidly connected together through bolts, so that the hybrid stator cannot axially move and the air gap is kept uniform.

[0015] According to the application, the modulation teeth comprise main teeth and split teeth, the main teeth are fixed to the stator yoke, annular windings are arranged on the main teeth, a plurality of split teeth are arranged on the top of each main tooth, the split teeth are the same in size and are arranged in a circumferential direction, and the number of the split teeth on a single main tooth is odd. The split teeth are used to divide a single tooth into a plurality of small teeth, the geometric structure of the magnetic circuit is changed, the magnetic conductance presents periodic variation in space, the magnetic conductance distribution and the magnetic field harmonic are adjusted, and the air gap magnetic field is actively modulated. The straight teeth have no magnetic modulation effect, and the split teeth have a magnetic field modulation effect.

[0016] According to the application, the stator yoke, the straight teeth and the modulation teeth are made of high-performance silicon steel sheets of magnetic conductive material.

[0017] According to the application, the annular windings are made of pure copper wires, the annular windings are arranged on the straight teeth and the modulation teeth, the two sets of annular windings are independent of each other, three-phase alternating currents are input into the corresponding windings according to actual working conditions, and a rotating magnetic field is generated. The annular windings adopt a concentrated winding method, the length of the end winding can be shortened, the copper loss is reduced, and the efficiency is improved.

[0018] According to the application, the low-speed rotor comprises low-speed magnetic steels and a low-speed rotor disc, the low-speed rotor disc is provided with a plurality of low-speed magnetic steels on one side, the low-speed magnetic steels are opposite to the modulation teeth, and the low-speed magnetic steels and the modulation teeth form a low-speed unit motor, and the gap between the low-speed magnetic steels and the modulation teeth is a first air gap.

[0019] According to the application, the high-speed rotor comprises high-speed magnetic steels and a high-speed rotor disc, the high-speed rotor disc is provided with a plurality of high-speed magnetic steels on one side, the high-speed magnetic steels are in the shape of a sector, the high-speed magnetic steels are opposite to the straight teeth, and the high-speed magnetic steels and the straight teeth form a high-speed unit motor, and the gap between the high-speed magnetic steels and the straight teeth is a second air gap.

[0020] According to the application, the pole pair number of the low-speed magnetic steels is greater than the pole pair number of the high-speed magnetic steels, one N-pole magnetic steel and one S-pole magnetic steel form a pole pair, if the number of the high-speed magnetic steels is n h , then the pole pair number is n h / 2, from n=60*f / p, the magnetic steels with a small pole pair number are arranged on the high-speed rotor disc to move at a high speed, and the magnetic steels with a large pole pair number are arranged on the low-speed rotor disc to move at a low speed, n is the rotating speed, f is the frequency, and p is the pole pair number, under the premise that the frequency is constant, the greater the pole pair number, the smaller the rotating speed, and the size of the low-speed magnetic steel is smaller than that of the high-speed magnetic steel.

[0021] The magnetizing directions of the low-speed magnetic steels and the high-speed magnetic steels are opposite to each other in pairs along the axial direction.

[0022] The working method of the split-tooth type magnetic field modulation axial flux composite motor is as follows.

[0023] (1) When the high-speed output is performed, the annular winding on the straight teeth is connected to the current, the high-speed magnetic steels and the high-speed rotor disc generate a rotor rotating magnetic field, the pole pair number of the magnetic field is the same as the pole pair number of the stator rotating magnetic field generated by the annular winding of the straight teeth, and the high-speed output is performed to the outside.

[0024] (2) When the low-speed output is performed, the annular winding on the modulation teeth is connected to the current to generate a stator rotating magnetic field with a pole pair number of p L , the magnetic circuit structure and the magnetic field distribution are changed through N t split teeth, the magnetic field with the pole pair number of p L is modulated into a low-speed magnetic field with a pole pair number of N t -p L , at this time, the pole pair number of the modulated magnetic field matches the pole pair number of the magnetic field generated by the N L low-speed magnetic steels, that is, 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 the low pole pair number is modulated into a low-speed magnetic field with a high pole pair number through the magnetic field modulation of the modulation teeth, and the low-speed magnetic field with the high pole pair number interacts with the low-speed magnetic field with the high pole pair number generated by the low-speed rotor to perform the low-speed large torque output to the outside.

[0025] The application has the advantages that:

[0026] 1. The low-speed unit motor utilizes the magnetic field modulation principle, constructs a magnetic gear device, converts the high-speed rotating magnetic field into a low-speed rotor magnetic field, realizes the low-speed and large-torque output to the outside, and ensures that the high-speed unit motor and the low-speed unit motor can keep uniform in the radial dimension.

[0027] 2. The application can flexibly switch the high-speed unit motor and the low-speed unit motor according to the actual working condition, and ensures that the high-speed unit motor and the low-speed unit motor can keep running near the high-efficiency rated point in the low-speed and high-speed states.

[0028] 3. The composite motor does not need external transmission devices, improves the reliability and efficiency of the whole system, and reduces the subsequent maintenance cost.

[0029] 4. The high-speed unit motor and the low-speed unit motor work independently and do not affect each other, share the intermediate stator yoke, save the axial space, and do not cause magnetic circuit coupling.

[0030] 5. The application can flexibly design the split tooth number according to the actual speed ratio to meet the requirement of the magnetic gear transmission ratio. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a three-dimensional schematic view of the application.

[0032] Figure 2 is an explosion schematic view of the application.

[0033] Figure 3 is a mixed stator structure schematic view of the application.

[0034] Figure 4 is a high-speed rotor structure schematic view of the application.

[0035] Figure 5 is a low-speed rotor structure schematic view of the application.

[0036] Figure 6 is a structure schematic view of a single ring winding of the application.

[0037] Figure 7 is a straight-line expansion view of the application.

[0038] Figure 8 is a magnetic field modulation effect principle diagram of the application.

[0039] Figure 9 is a Fourier decomposition diagram of the air gap magnetic density under the load working condition of the application.

[0040] REFERENCE SIGNS:

[0041] 1. Hybrid stator; 2. Low-speed rotor; 3. High-speed rotor;

[0042] 11. Stator yoke; 12. Straight teeth; 13. Main teeth; 14. Split teeth; 15. Circular winding;

[0043] 21. Low-speed magnet; 22. Low-speed rotor disc;

[0044] 31. High-speed magnets; 32. High-speed rotor disk;

[0045] 41. First air gap; 42. Second air gap. Detailed Implementation

[0046] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0047] Example 1:

[0048] like Figures 1-7 As shown, this embodiment provides a split-tooth magnetic field modulation axial flux composite motor, including a housing, a shaft, a hybrid stator 1, a low-speed rotor 2 and a high-speed rotor 3. The hybrid stator 1 is fixed to the housing, 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 shaft, and the two ends of the shaft are fixed to the housing by bearing brackets.

[0049] The hybrid stator 1 includes a stator yoke 11, straight teeth 12, and modulation teeth. Several straight teeth 12 and modulation teeth are symmetrically arranged around both sides of the stator yoke 11, and annular windings 15 are provided on the straight teeth 12 and modulation teeth. The hybrid stator 1 and the housing are rigidly connected together by bolts to ensure that the hybrid stator 1 will not move axially and to keep the air gap uniform.

[0050] The modulation teeth include main teeth 13 and split teeth 14. The main teeth 13 are fixed to the stator yoke 11 and have annular windings 15. Several split teeth 14, all of the same size and arranged circumferentially, are located on the top of the main teeth 13. The number of split teeth 14 on a single main tooth 13 is odd. By dividing a single tooth into multiple smaller teeth using the split teeth 14, the geometry of the magnetic circuit is altered, causing the magnetic permeability to exhibit periodic changes in space. This adjusts the magnetic permeability distribution and magnetic field harmonics, achieving active modulation of the air gap magnetic field. The straight teeth 12 have no magnetic modulation effect, while the split teeth 14 have a magnetic field modulation function. Both the straight teeth 12 and the modulation teeth are stator teeth, with adjacent stator teeth forming stator slots. The number of stator slots is a multiple of 3.

[0051] The main tooth 13 has Q teeth, and each main tooth 13 has a split teeth 14, forming a-1 small slots and N. t The total number of split teeth, Q*a=N t .

[0052] The stator yoke 11, the straight teeth 12 and the modulation teeth are made of high-performance silicon steel sheet of magnetic conductive material.

[0053] The ring winding 15 is made of pure copper wire, and the structure of a single ring winding 15 is shown in Figure 6 Fig. 2, which is arranged on both sides of the hybrid stator 1 in the circumferential direction. In this embodiment, the concentrated winding form is adopted, and a single ring winding is wound on a single tooth only, and there is no overlapping part between the ring windings, and the end part is short, which saves copper wire and has high efficiency. The circumferential arrangement of the ring winding is not limited to the concentrated winding, but also applies to the distributed winding.

[0054] The low-speed rotor 2 includes low-speed magnetic steel 21 and low-speed rotor disc 22, and the low-speed rotor disc 22 is provided with N L low-speed magnetic steel 21 on one side, and 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 pole pair number p L of the stator rotating magnetic field of the low-speed unit motor satisfies the relationship formula p L +N L / 2=Q*a, and N L is an even number.

[0055] In this embodiment, the pole pair number p L of the stator rotating magnetic field of the low-speed unit motor is 3, the number of low-speed magnetic steel 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, which satisfies the relationship formula 3+84 / 2=9*5.

[0056] The high-speed rotor 3 includes high-speed magnetic steel 31 and high-speed rotor disc 32, and the high-speed rotor disc 32 is provided with N H high-speed magnetic steel 31 on one side, and the N H high-speed magnetic steel 31 with opposite polarity is arranged in sequence in the circumferential direction. The high-speed magnetic steel 31 is in the shape of a fan, and the high-speed magnetic steel 31 is opposite to the straight teeth 12 to form a high-speed unit motor. The pole pair number of the stator magnetic field of the high-speed unit motor is N H / 2, and N H is an even number. The gap between the high-speed magnetic steel and the straight teeth is the second air gap. Since the pole pair number of the high-speed magnetic steel 31 is small, the volume of the magnetic steel is large. In order to effectively suppress the eddy current loss of the magnetic steel and reduce the risk of heating and demagnetization, the high-speed magnetic steel 31 is segmented in the circumferential direction, as shown in Figure 4 , and the high-speed magnetic steel 31 is divided into three segments.

[0057] The pole pair number of the low-speed magnetic steel 21 is greater than that of the high-speed magnetic steel 31, and a pair of poles is composed of one N-pole magnetic steel and one S-pole magnetic steel. If the number of high-speed magnetic steels is n h , then the 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 move at high speed, while the magnets with more pole pairs are arranged on the low-speed rotor disk and move at low speed. n is the rotational speed, f is the frequency, and p is the number of pole pairs. Under the premise that the frequency remains unchanged, the larger the number of pole pairs, the smaller the rotational speed. The size of the low-speed magnet 21 is smaller than that of the high-speed magnet 31.

[0058] The magnetization directions of the low-speed magnet 21 and the high-speed magnet 31 are opposite to each other along the axial direction.

[0059] The linear development diagram of this embodiment is as follows: Figure 7 As shown, when the low-speed unit motor is working, the magnetic excitation line forms a closed loop through low-speed magnet 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 magnet 21 - low-speed rotor disk 22; when the high-speed unit motor is working, the magnetic excitation line forms a closed loop through high-speed magnet 31 - second air gap 42 - straight tooth 12 - stator yoke 11 - straight tooth 12 - second air gap 42 - high-speed magnet 31 - high-speed rotor disk 32. The two share a set of stator yoke 11, which greatly reduces the axial dimension and increases the torque density.

[0060] The principle of the magnetic field modulation effect of this invention is as follows: Figure 8 As shown, the low-speed end magnetic field has 42 pole pairs. After being modulated by 45 split teeth, a high-speed magnetic field with 3 pole pairs is generated in the first air gap. The low-speed rotor 2 rotates very slowly, but under the magnetic modulation effect of the split teeth 14, the slow speed can generate a rotating magnetic field with a 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 dimension to achieve the switching of different output modes.

[0061] The working method of the above-mentioned split-tooth magnetic field modulated axial flux composite motor is as follows:

[0062] (1) When the high speed is output, the current is passed through the annular winding 15 on the straight tooth 12, and the high speed magnet 31 and the high speed rotor disk 32 generate the 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 in the straight tooth part, and the high speed is output to the outside.

[0063] (2) At low speed output, current is passed through the annular winding 15 on the modulation tooth, generating a pole pair number of p. L The stator rotating magnetic field, through N t A split tooth alters the magnetic circuit structure and magnetic field distribution, making p L A magnetic field with a pole pair number of N is modulated. t -p L The low-speed magnetic field, at this time, the modulated magnetic field and N LThe magnetic field generated by the low-speed magnetic steel matches the number of pole pairs, i.e. N L / 2=N t -p L The winding generates a high-speed rotating magnetic field with a low number of pole pairs, which is modulated by the magnetic field of the modulation teeth to become a low-speed magnetic field with a high number of pole pairs, which interacts with the low-speed magnetic field with a high number of pole pairs generated by the low-speed rotor 2 to output a low-speed large torque to the outside.

[0064] Based on the method of three-dimensional finite element analysis, the composite motor is simulated, the magnetic field modulation principle of the modulation side unit motor is simulated, and the Fourier decomposition results of the air gap magnetic flux density under the load condition are shown in Figure 9 The harmonics are mainly 42 times, i.e. the fundamental magnetic field of 42 pole pairs, indicating that the air gap magnetic field is a 42-pole magnetic field, in addition to a small amount of 3rd harmonic, it can be seen that the high-speed stator rotating magnetic field with 3 pole pairs is modulated to a low-speed rotating magnetic field with 42 pole pairs under the magnetic modulation of the 45 modulation teeth, and the number of pole pairs of the rotating magnetic field generated by the low-speed magnetic steel is the same, according to k=N L / p L , the two interact with each other to finally realize the output effect of a low-speed large torque with a transmission ratio of 14, so that the composite motor has two output states of high speed and low speed large torque.

Claims

1. A split tooth field modulation axial flux compound electric machine, characterized in that, The machine shell, the rotating shaft, the mixing stator, the low-speed rotor and the high-speed rotor are included, the mixing stator is fixed to the machine shell, the low-speed rotor and the high-speed rotor are symmetrically arranged on both sides of the mixing stator, the low-speed rotor and the high-speed rotor are sleeved on the rotating shaft, and the rotating shaft is fixed to the machine shell through the bearing frame at both ends; The mixing stator includes the stator yoke, the straight teeth and the modulation teeth, the straight teeth and the modulation teeth are symmetrically arranged on both sides of the stator yoke, the ring-shaped winding is arranged on the straight teeth and the modulation teeth, the modulation teeth include the main teeth and the split teeth, the main teeth are fixed to the stator yoke, the ring-shaped winding is arranged on the main teeth, the split teeth are arranged on the top of the main teeth, the split teeth are the same in size, are arranged in the circumferential direction, and the number of the split teeth on a single main tooth is odd; The low-speed rotor includes the low-speed magnetic steel and the low-speed rotor disc, the low-speed magnetic steel is arranged on one side of the low-speed rotor disc, the low-speed magnetic steel is opposite to the modulation teeth, the low-speed magnetic steel and the modulation teeth form a low-speed unit motor, and the gap between the low-speed magnetic steel and the modulation teeth is a first air gap; The high-speed rotor includes the high-speed magnetic steel and the high-speed rotor disc, the high-speed magnetic steel is arranged on one side of the high-speed rotor disc, the high-speed magnetic steel is in the shape of a sector, the high-speed magnetic steel is opposite to the straight teeth, the high-speed magnetic steel and the straight teeth form a high-speed unit motor, and the gap between the high-speed magnetic steel and the straight teeth is a second air gap; The pole pair number of the low-speed magnetic steel is greater than that of the high-speed magnetic steel, and the size of the low-speed magnetic steel is smaller than that of the high-speed magnetic steel.

2. The split tooth magnetic field modulation axial flux composite electric machine of claim 1, wherein, The stator yoke, the straight teeth and the modulation teeth are made of high-performance silicon steel sheet of magnetic conductive material.

3. The split tooth magnetic field modulation axial flux composite electric machine of claim 1, wherein, The ring-shaped winding is made of pure copper wire.

4. The method of claim 2, wherein the split tooth axial flux motor is a split tooth axial flux motor. The steps are as follows: (1) when the high-speed output is performed, the ring-shaped winding on the straight teeth is connected to the current, the high-speed magnetic steel and the high-speed rotor disc generate the rotor rotating magnetic field, the pole pair number of the magnetic field is the same as that of the stator rotating magnetic field generated by the part of the ring-shaped winding of the straight teeth, and the high-speed output is performed to the outside. (2) At low speed output, the annular winding on the modulation tooth is passed through current to produce a stator rotating magnetic field with p L pole pairs, which changes the magnetic circuit structure and magnetic field distribution through N t split teeth to modulate the magnetic field with p L pole pairs into a low speed magnetic field with N t -p L pole pairs. At this time, the modulated magnetic field and the magnetic field generated by N L low speed magnetic steel match in pole pairs, i.e. N L / 2=N t -p L , the winding generates a high speed rotating magnetic field with low pole pairs, which is modulated into a low speed magnetic field with high pole pairs through the magnetic field modulation of the modulation tooth, and interacts with the low speed magnetic field with high pole pairs generated by the low speed rotor to output low speed and large torque to the outside.

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