Single-ring sum-difference dual-modulation three-rotor coaxial magnetic gear and new energy vehicle hub motor

Abstract

The present invention provides a single-ring sum-difference dual-modulation three-rotor coaxial magnetic gear and a new energy vehicle hub motor. The magnetic gear includes an H-shaped dual-modulation magnetic tuning ring, an outer rotor, an inner rotor, and an intermediate rotor. The inner rotor, intermediate rotor, and outer rotor are coaxially nested from the inside out. The H-shaped dual-modulation magnetic tuning ring is located between the inner rotor, intermediate rotor, and outer rotor and is coaxially arranged with the inner rotor, intermediate rotor, and outer rotor. The intermediate rotor serves as the power input rotor, and the inner rotor and outer rotor serve as the power output rotors. A sum modulation effect is applied from the intermediate rotor to the inner rotor, and a difference modulation effect is applied from the intermediate rotor to the outer rotor. The sum modulation effect and the difference modulation effect share the H-shaped dual-modulation magnetic tuning ring, so that the H-shaped dual-modulation magnetic tuning ring simultaneously modulates the axial magnetic flux and the transverse magnetic flux. The present invention can improve the torque transmission capability of the magnetic gear, suppress magnetic saturation, enhance the magnetic field modulation effect, and increase the torque density of the magnetic gear.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a single-ring sum-difference double-modulation three-rotor coaxial magnetic gear and a new energy vehicle hub motor. Background Art

[0002] New energy vehicles (NEVs) have attracted widespread attention from researchers and developers due to their zero-emission and high-energy efficiency. Among these, NEVs with distributed drive systems are a growing trend, offering advantages such as a simple transmission structure, high transmission efficiency, and flexible vehicle control. Direct-drive in-wheel motors, as the core power component of distributed drive systems, are typically connected directly to the wheels. They not only face the output torque performance requirements of the vehicle's powertrain under conditions such as acceleration, deceleration, and climbing, but also must meet the drive requirements for stable operation under complex road conditions such as rugged mountain roads and muddy roads. Therefore, achieving excellent low-speed, high-torque capabilities is a key concern in the field of in-wheel motor research. Furthermore, given the limited space within a vehicle's wheel hub, achieving higher torque density presents a challenging problem that must be addressed in the design of in-wheel motors.

[0003] Under the influence of a modulated magnetic core, magnetic gears can achieve bidirectional modulation of low-speed and high-speed magnetic fields, thereby achieving electromechanical energy conversion through harmonic magnetic field coupling. Because the inner and outer rotors are driven by modulated magnetic field coupling and do not contact each other during transmission, magnetic gears have advantages over mechanical gears, such as no frictional vibration, no need for lubrication and maintenance, no noise, and a compact structure. They have broad application prospects in the field of field-modulated hub motors for new energy vehicles.

[0004] However, how to improve the torque transmission capability of magnetic gears, suppress magnetic saturation, enhance the magnetic field modulation effect, and increase the torque density of magnetic gears are technical problems that need to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a single-ring sum-difference dual-modulation three-rotor coaxial magnetic gear and a new energy vehicle hub motor to improve the torque transmission capability of the magnetic gear, suppress magnetic saturation, enhance the magnetic field modulation effect, and increase the torque density of the magnetic gear.

[0006] One aspect of the present invention provides a single-ring sum-difference double-modulation three-rotor coaxial magnetic gear, comprising an H-shaped double-modulation magnetic ring, an outer rotor, an inner rotor and an intermediate rotor;

[0007] The inner rotor, intermediate rotor and outer rotor are coaxially nested from the inside to the outside; the H-shaped double-modulation magnetic ring is located between the inner rotor, intermediate rotor and outer rotor, and is coaxially configured with the inner rotor, intermediate rotor and outer rotor;

[0008] Between the intermediate rotor and the H-shaped double-modulation magnetic regulating ring, there is an intermediate rotor radial inner air gap, an intermediate rotor radial outer air gap, and an intermediate rotor axial air gap; between the inner rotor and the H-shaped double-modulation magnetic regulating ring, there is an inner rotor radial outer air gap; between the outer rotor and the H-shaped double-modulation magnetic regulating ring, there is an outer rotor radial inner air gap, an outer rotor radial outer air gap, and an outer rotor axial air gap;

[0009] The intermediate rotor serves as the power input rotor, and the inner rotor and the outer rotor serve as the power output rotors. A sum modulation effect is adopted from the intermediate rotor to the inner rotor, and a difference modulation effect is adopted from the intermediate rotor to the outer rotor. The sum modulation effect and the difference modulation effect share the H-shaped double-modulation magnetic modulation ring, so that the H-shaped double-modulation magnetic modulation ring simultaneously modulates the axial magnetic flux and the transverse magnetic flux.

[0010] External power is input by the intermediate rotor. The magnetic field generated by the intermediate rotor's magnetic poles undergoes radial sum modulation effect and axial difference modulation effect, and the effective harmonics generated in the air gap are coupled with the magnetic fields generated by the inner rotor's magnetic poles and the outer rotor's magnetic poles, respectively, to achieve power transmission from the intermediate rotor to the inner rotor and outer rotor.

[0011] The transmission ratio between the intermediate rotor and the outer rotor is different from the transmission ratio between the intermediate rotor and the inner rotor to achieve differential transmission.

[0012] Another aspect of the present invention provides a new energy vehicle hub motor, which includes the magnetic gear mentioned above.

[0013] The single-ring sum-difference dual-modulation three-rotor coaxial magnetic gear and new energy vehicle hub motor provided by the present invention have the following beneficial effects:

[0014] (1) The magnetic gear of the present invention uses an H-shaped double-modulation magnetic ring for radial sum modulation and axial differential modulation, which reduces the number of magnetic adjustment magnets. Compared with the traditional double-modulation magnetic ring double-modulation magnetic gear topology, the structure of the present invention is more compact and smaller in size, and has more advantages in relatively narrow use scenarios such as new energy vehicle hub motors.

[0015] (2) Since the present invention adopts both sum modulation effect and difference modulation effect, it has a stronger field modulation effect and a higher torque transmission capability compared with the traditional topological structure.

[0016] (3) Since the radial sum modulation and axial differential modulation of the magnetic gear of the present invention share the same H-shaped double modulation magnetic ring, the transmission ratio between the intermediate rotor and the inner rotor is not equal to the transmission ratio between the intermediate rotor and the outer rotor. Therefore, transmission with different transmission ratios can be performed without adding other transmission structures.

[0017] (4) In the magnetic gear of the present invention, the magnetization method of the permanent magnets on the inner rotor, the intermediate rotor and the outer rotor all adopts tangential magnetization, and a pole shoe is embedded between two adjacent permanent magnets for auxiliary modulation, so that the air gap magnetic flux density is larger, the waveform is close to a sine waveform, the torque transmission capacity is improved, and the transmission is more stable.

[0018] (5) The magnetic gear of the present invention adopts an H-shaped double-modulation magnetic ring and a magnetization method adopted by the permanent magnets on the inner rotor, the intermediate rotor and the outer rotor, so that it has both axial and transverse magnetic flux paths. It can reduce the influence of the magnetic saturation effect without reducing the total flux generated by the permanent magnet, thereby achieving the effect of anti-magnetic saturation effect.

[0019] (6) When performing the magnetic pole pair ratio matching, the magnetic gear matches the magnetic pole pairs of the inner rotor and the outer rotor based on the magnetic pole pairs on the intermediate rotor. Compared with the traditional method of matching the magnetic pole pairs of the intermediate rotor and the outer rotor based on the magnetic pole pairs on the inner rotor, it has the advantages of being easier to achieve the magnetic pole pair ratio required for the optimal field modulation effect and easier to achieve monotonic magnetic ring and differential double modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the overall structure of a single-ring sum-difference double-modulation three-rotor coaxial magnetic gear in an embodiment of the present invention;

[0021] Figure 2 It is a cross-sectional structural diagram of the inner rotor and the intermediate rotor;

[0022] Figure 3 It is a cross-sectional structural diagram of the inner rotor and the outer rotor;

[0023] Figure 4 1 is a side structural diagram of a single-ring sum-difference double-modulation three-rotor coaxial magnetic gear in an embodiment of the present invention;

[0024] Figure 5 It is a structural diagram of the H-type double-modulation magnetic ring;

[0025] Figure 6 It is a structural diagram of the H-shaped double-modulation magnetic ring and epoxy resin jacket;

[0026] Figure 7 A comparison diagram of the magnetic field strength in the air gap between the magnetic gear of the present invention and the traditional magnetic concentrating magnetic gear;

[0027] Figure 8 The figure is a comparison diagram of the spatial harmonic spectrum of the magnetic induction intensity in the air gap of the magnetic gear of the present invention and the traditional magnetic concentrating magnetic gear. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0029] See also Figures 1 to 6 The single-ring and differential double-modulation three-rotor coaxial magnetic gear provided in an embodiment of the present invention includes an H-shaped double-modulation magnetic ring 1, an outer rotor 2, an inner rotor 3, an intermediate rotor 4, and a shell 6.

[0030] The inner rotor 3, the intermediate rotor 4 and the outer rotor 2 are coaxially nested from the inside to the outside; the H-shaped double-modulation magnetic tuning ring 1 is located between the inner rotor 3, the intermediate rotor 4 and the outer rotor 2, and is coaxially configured with the inner rotor 3, the intermediate rotor 4 and the outer rotor 2.

[0031] The H-shaped double-modulation magnetic tuning ring 1 is fixed to the housing 6 by bolts. An epoxy resin jacket 19 is arranged between two adjacent H-shaped double-modulation magnetic tuning rings 1 to separate the two adjacent H-shaped double-modulation magnetic tuning rings 1 from each other. The H-shaped double-modulation magnetic tuning ring 1 is specifically made of stacked silicon steel sheets.

[0032] An intermediate rotor radial inner air gap 5 , an intermediate rotor radial outer air gap 12 , and an intermediate rotor axial air gap 17 are provided between the intermediate rotor 4 and the H-shaped double modulation magnetic tuning ring 1 .

[0033] An inner rotor radial outer air gap 7 is provided between the inner rotor 3 and the H-shaped double-modulation magnetic tuning ring 1 .

[0034] An outer rotor radial inner air gap 15 , an outer rotor radial outer air gap 16 , and an outer rotor axial air gap 18 are provided between the outer rotor 2 and the H-shaped double-modulation magnetic tuning ring 1 .

[0035] Specifically, the permanent magnets on the inner rotor 3, the intermediate rotor 4 and the outer rotor 2 are all tangentially magnetized, and the magnetization directions of two adjacent permanent magnets are opposite, forming an NS structure, achieving the effect of multiple magnetic circuits, thereby realizing the function of improving the stability of the output torque.

[0036] The three side end surfaces of the H-shaped double-modulation magnetic tuning ring 1 are axially aligned with the outer end surfaces of the inner rotor 3, the intermediate rotor 4 and the outer rotor 2 respectively.

[0037] In this embodiment, the inner rotor 3, the intermediate rotor 4 and the outer rotor 2 adopt a spoke structure. The inner rotor 3 includes an inner rotor permanent magnet 8 and an inner rotor pole shoe 10. The inner rotor pole shoe 10 is embedded between two adjacent inner rotor permanent magnets 8. The inner rotor pole shoe 10 and the inner rotor permanent magnet 8 support each other and perform magnetic field modulation together with the H-shaped double-modulation magnetic tuning ring 1.

[0038] The intermediate rotor 4 includes an intermediate rotor permanent magnet 9 and an intermediate rotor pole shoe 11. The intermediate rotor pole shoe 11 is embedded between two adjacent intermediate rotor permanent magnets 9. The intermediate rotor pole shoe 11 and the intermediate rotor permanent magnet 9 support each other and perform magnetic field modulation together with the H-shaped double modulation magnetic tuning ring 1.

[0039] The outer rotor 2 includes an outer rotor permanent magnet 14 and an outer rotor pole shoe 13. The outer rotor pole shoe 13 is embedded between two adjacent outer rotor permanent magnets 14. The outer rotor pole shoe 13 and the outer rotor permanent magnet 14 support each other and perform magnetic field modulation together with the H-shaped double modulation magnetic tuning ring 1.

[0040] The intermediate rotor 4 serves as the power input rotor, and the inner rotor 3 and the outer rotor 2 serve as the power output rotors. A sum modulation effect is adopted from the intermediate rotor 4 to the inner rotor 3, and a difference modulation effect is adopted from the intermediate rotor 4 to the outer rotor 2. The sum modulation effect and the difference modulation effect share the H-type dual modulation magnetic tuning ring 1, so that the H-type dual modulation magnetic tuning ring 1 simultaneously modulates the axial magnetic flux and the transverse magnetic flux.

[0041] External power is input by the intermediate rotor 4. The magnetic field generated by the magnetic poles of the intermediate rotor 4 undergoes radial sum modulation effect and axial difference modulation effect. The effective harmonics generated in the air gap (including the radial inner air gap 5 of the intermediate rotor, the radial outer air gap 12 of the intermediate rotor, the axial air gap 17 of the intermediate rotor, the radial outer air gap 7 of the inner rotor, the radial inner air gap 15 of the outer rotor, the radial outer air gap 16 of the outer rotor, and the axial air gap 18 of the outer rotor) are respectively coupled with the magnetic fields generated by the magnetic poles of the inner rotor 3 and the magnetic poles of the outer rotor 2, so that power is transmitted from the intermediate rotor 4 to the inner rotor 3 and the outer rotor 2, realizing the double modulation effect of the monotonic magnetic ring and the multi-magnetic flux circuit of the monotonic magnetic ring, improving the utilization efficiency of the magnetic field, reducing the amount of modulation magnet blocks, and making the spatial structure more reasonable.

[0042] The transmission ratio between the intermediate rotor 4 and the outer rotor 2 is different from the transmission ratio between the intermediate rotor 4 and the inner rotor 3 to achieve differential transmission.

[0043] In this embodiment, the number of h-type double modulation magnetic tuning rings 1 is N. s , the number of magnetic pole pairs P1 of the inner rotor permanent magnet 8, the number of magnetic pole pairs P2 of the intermediate rotor permanent magnet 9, and the number of magnetic pole pairs P3 of the outer rotor permanent magnet 14 satisfy the relationship:

[0044] N s= P1+ P2;

[0045] N s = P3- P2.

[0046] The transmission ratio G between the intermediate rotor 4 and the inner rotor 3 r1 = P1 / P2, the transmission ratio between the intermediate rotor 4 and the outer rotor 2 is G r2 = P3 / P2.

[0047] Specifically in this embodiment, the ratio of the number of magnetic pole pairs of the inner rotor 3 and the intermediate rotor 4 is 15:4; the ratio of the number of magnetic pole pairs of the intermediate rotor 4 and the outer rotor 2 is 4:23, thereby achieving a radial sum modulation effect and an axial differential modulation effect, and the radial modulation and axial modulation share the magnetic field modulation effect of the H-shaped double modulation magnetic tuning ring 1, thereby improving the utilization efficiency of the magnetic field.

[0048] In this embodiment, the axial length L of the h-shaped double modulation magnetic tuning ring 1 is s , the axial length L of the intermediate rotor 4 h , the axial length L1 of the outer rotor 2, the axial thickness L of the h-type double modulation magnetic ring 1 v , the thickness L of the intermediate rotor axial air gap 17 d1 , the thickness L of the outer rotor axial air gap 18 d2 , satisfying the relationship:

[0049] L s = L h + L1+ L v + L d1 + L d2 .

[0050] The radial height H of the h-type double modulation magnetic ring 1 s , the radial length H of the intermediate rotor 4 h , the radial thickness H of the h-type double modulation magnetic ring 1 v , the thickness H of the radial inner air gap 5 of the intermediate rotor d1 , the thickness H of the radial outer air gap 12 of the intermediate rotor d2 , satisfying the relationship:

[0051] H s = H h + H1+ 2H v + H d1 + H d2 .

[0052] Specifically in this embodiment, the interval between adjacent inner rotor permanent magnets 8 is 6°, the interval between adjacent middle rotor permanent magnets 9 is 22.5°, the interval between adjacent outer rotor permanent magnets 14 is 3.91°, and the interval between adjacent H-shaped double-modulation magnetic tuning rings 1 is 9.47°.

[0053] When performing magnetic pole pair ratio matching for the single-ring sum-difference double-modulation three-rotor coaxial magnetic gear, the magnetic pole pair ratio is performed on the inner rotor 3 and the outer rotor 2 based on the magnetic pole pair ratio on the intermediate rotor 4 .

[0054] Specifically, when determining the magnetic pole pair ratio, first select a gear ratio that provides the best transmission performance based on the requirements. If the gear ratio is too small, the output torque may be low, failing to meet the required torque. If the gear ratio is too large, the output speed may be slow, failing to meet the required speed. Secondly, while meeting the torque and speed requirements, the selected gear ratio should strive to achieve high magnetic gear transmission efficiency. That is, while ensuring output torque and speed, the gear ratio is generally set between 2.75 and 6.5 when determining the magnetic pole pair ratio, with the gear ratios typically being n.25, n.5, or n.75 (where n is an integer).

[0055] When performing magnetic pole pair ratio matching, the magnetic pole pair ratio of the inner rotor 3 and the outer rotor 2 should be based on the magnetic pole pair ratio of the intermediate rotor 4; while meeting the requirements of the selected transmission ratio, the inner rotor 3, the intermediate rotor 4 and the outer rotor 2 can simultaneously obtain magnetic pole pairs with relatively ideal transmission effects.

[0056] When balancing the number of magnetic pole pairs, the appropriate number of pole pairs for the intermediate rotor 4 should be selected. Excessive pole pairs can easily lead to magnetic saturation and end-magnetic leakage, hindering the full utilization of the magnetic field generated by the permanent magnets. Too few pole pairs can easily result in low and unstable output torque. When balancing speed and output torque, the number of pole pairs for the intermediate rotor 4 is generally selected to be 4 to 6.

[0057] After determining the number of magnetic pole pairs of the intermediate rotor 4, when matching the number of magnetic pole pairs of the inner rotor 3 and the outer rotor 2, first, the ratio of the number of magnetic pole pairs of the inner rotor 3, the outer rotor 2 and the intermediate rotor 4 should be selected to be equal to the selected transmission ratio; secondly, the relationship between the selected number of magnetic pole pairs and the number of H-type double modulation tuning rings 1 must satisfy the relationship between the number of magnetic pole pairs and the number of H-type double modulation tuning rings 1 required for the sum modulation effect and the differential modulation effect, so as to achieve the coexistence of the sum modulation effect and the differential modulation effect; finally, the number of tuning rings used for the radial sum modulation effect and the axial differential modulation effect should be equal, so as to achieve the effects of single-tone magnetic rings and differential double modulation.

[0058] The magnetic gear of the present invention is compared and analyzed with the traditional magnetic gear. Figure 7 It can be seen that the magnetic field intensity in the air gap of the magnetic gear of the present invention is significantly higher than that of the traditional magnetic gear with concentrated magnetic field, and the magnetic field modulation effect of the magnetic gear of the present invention is significantly enhanced. Figure 8 It can be seen that compared with the traditional magnetic gear with concentrated magnetic flux, the peak value of the effective harmonic component in the air gap of the magnetic gear of the present invention is significantly improved, which is conducive to improving the torque density of the magnetic gear.

[0059] An embodiment of the present invention further provides a new energy vehicle hub motor, which includes the magnetic gear described above.

[0060] In summary, the single-ring sum-difference dual-modulation three-rotor coaxial magnetic gear and new energy vehicle hub motor provided by the present invention have the following beneficial effects:

[0061] (1) The magnetic gear of the present invention uses an H-shaped double-modulation magnetic ring for radial sum modulation and axial differential modulation, which reduces the number of magnetic adjustment magnets. Compared with the traditional double-modulation magnetic ring double-modulation magnetic gear topology, the structure of the present invention is more compact and smaller in size, and has more advantages in relatively narrow use scenarios such as new energy vehicle hub motors.

[0062] (2) Since the present invention adopts both sum modulation effect and difference modulation effect, it has a stronger field modulation effect and a higher torque transmission capability compared with the traditional topological structure.

[0063] (3) Since the radial sum modulation and axial differential modulation of the magnetic gear of the present invention share the same H-shaped double modulation magnetic ring, the transmission ratio between the intermediate rotor and the inner rotor is not equal to the transmission ratio between the intermediate rotor and the outer rotor. Therefore, transmission with different transmission ratios can be performed without adding other transmission structures.

[0064] (4) In the magnetic gear of the present invention, the magnetization method of the permanent magnets on the inner rotor, the intermediate rotor and the outer rotor all adopts tangential magnetization, and a pole shoe is embedded between two adjacent permanent magnets for auxiliary modulation, so that the air gap magnetic flux density is larger, the waveform is close to a sine waveform, the torque transmission capacity is improved, and the transmission is more stable.

[0065] (5) The magnetic gear of the present invention adopts an H-shaped double-modulation magnetic ring and a magnetization method adopted by the permanent magnets on the inner rotor, the intermediate rotor and the outer rotor, so that it has both axial and transverse magnetic flux paths. It can reduce the influence of the magnetic saturation effect without reducing the total flux generated by the permanent magnet, thereby achieving the effect of anti-magnetic saturation effect.

[0066] (6) When performing the magnetic pole pair ratio matching, the magnetic gear matches the magnetic pole pairs of the inner rotor and the outer rotor based on the magnetic pole pairs on the intermediate rotor. Compared with the traditional method of matching the magnetic pole pairs of the intermediate rotor and the outer rotor based on the magnetic pole pairs on the inner rotor, it has the advantages of being easier to achieve the magnetic pole pair ratio required for the optimal field modulation effect and easier to achieve monotonic magnetic ring and differential double modulation.

[0067] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0068] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A single-ring sum-difference double-modulation three-rotor coaxial magnetic gear, characterized in that: It includes an H-shaped double-modulation magnetic ring, an outer rotor, an inner rotor and an intermediate rotor; The inner rotor, intermediate rotor and outer rotor are coaxially nested from the inside to the outside; the H-shaped double-modulation magnetic ring is located between the inner rotor, intermediate rotor and outer rotor, and is coaxially configured with the inner rotor, intermediate rotor and outer rotor; Between the intermediate rotor and the H-shaped double-modulation magnetic regulating ring, there is an intermediate rotor radial inner air gap, an intermediate rotor radial outer air gap, and an intermediate rotor axial air gap; between the inner rotor and the H-shaped double-modulation magnetic regulating ring, there is an inner rotor radial outer air gap; between the outer rotor and the H-shaped double-modulation magnetic regulating ring, there is an outer rotor radial inner air gap, an outer rotor radial outer air gap, and an outer rotor axial air gap; The intermediate rotor serves as the power input rotor, and the inner rotor and the outer rotor serve as the power output rotors. A sum modulation effect is adopted from the intermediate rotor to the inner rotor, and a difference modulation effect is adopted from the intermediate rotor to the outer rotor. The sum modulation effect and the difference modulation effect share the H-shaped double-modulation magnetic modulation ring, so that the H-shaped double-modulation magnetic modulation ring simultaneously modulates the axial magnetic flux and the transverse magnetic flux. External power is input by the intermediate rotor. The magnetic field generated by the intermediate rotor's magnetic poles undergoes radial sum modulation effect and axial difference modulation effect, and the effective harmonics generated in the air gap are coupled with the magnetic fields generated by the inner rotor's magnetic poles and the outer rotor's magnetic poles, respectively, to achieve power transmission from the intermediate rotor to the inner rotor and outer rotor. The transmission ratio between the intermediate rotor and the outer rotor is different from the transmission ratio between the intermediate rotor and the inner rotor to achieve differential transmission.

2. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 1, characterized in that: The permanent magnets on the inner rotor, the intermediate rotor and the outer rotor are all magnetized tangentially, and the magnetization directions of two adjacent permanent magnets are opposite.

3. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 1, characterized in that: The three side end faces of the H-shaped double-modulation magnetic tuning ring are axially aligned with the outer end faces of the inner rotor, the intermediate rotor and the outer rotor respectively.

4. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 1, characterized in that: The inner rotor, intermediate rotor and outer rotor adopt a spoke structure. The inner rotor includes inner rotor permanent magnets and inner rotor pole shoes. The inner rotor pole shoes are embedded between two adjacent inner rotor permanent magnets. The inner rotor pole shoes and the inner rotor permanent magnets support each other and work together with the H-shaped double modulation magnetic ring to modulate the magnetic field. The intermediate rotor includes an intermediate rotor permanent magnet and an intermediate rotor pole shoe. The intermediate rotor pole shoe is embedded between two adjacent intermediate rotor permanent magnets. The intermediate rotor pole shoe and the intermediate rotor permanent magnet support each other and perform magnetic field modulation together with the H-shaped double modulation magnetic ring. The outer rotor includes an outer rotor permanent magnet and an outer rotor pole shoe. The outer rotor pole shoe is embedded between two adjacent outer rotor permanent magnets. The outer rotor pole shoe and the outer rotor permanent magnet support each other and perform magnetic field modulation together with the H-shaped double modulation magnetic ring.

5. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 4, characterized in that: The number of h-type double modulation magnetic ring is N s , the number of magnetic pole pairs of the inner rotor permanent magnet P1, the number of magnetic pole pairs of the intermediate rotor permanent magnet P2 and the number of magnetic pole pairs of the outer rotor permanent magnet P3 satisfy the relationship: N s = P1+ P2; N s = P3- P2; The transmission ratio G between the intermediate rotor and the inner rotor r1 = P1 / P2, the transmission ratio between the intermediate rotor and the outer rotor is G r2 =P3 / P2.

6. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 1, characterized in that: The axial length L of the h-type double modulation magnetic ring s , the axial length L of the intermediate rotor h , the axial length of the outer rotor L1, the axial thickness of the h-type double modulation magnetic ring L v , the thickness of the intermediate rotor axial air gap L d1 , the thickness of the outer rotor axial air gap L d2 , satisfying the relationship: L s = L h + L1+ L v + L d1 + L d2 。 7. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 1, characterized in that: The radial height H of the h-type double modulation magnetic ring s , radial length H of the intermediate rotor h , the radial thickness H of the h-type double modulation magnetic ring v , the thickness H of the radial inner air gap of the intermediate rotor d1 , the thickness H of the radial outer air gap of the intermediate rotor d2 , satisfying the relationship: H s = H h + H1+ 2H v + H d1 + H d2 。 8. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 4, characterized in that: The interval between adjacent inner rotor permanent magnets is 6°, the interval between adjacent middle rotor permanent magnets is 22.5°, the interval between adjacent outer rotor permanent magnets is 3.91°, and the interval between adjacent H-shaped double-modulation magnetic tuning rings is 9.47°.

9. The single-ring sum-difference double-modulation three-rotor coaxial magnetic gear according to claim 1, characterized in that: When performing magnetic pole pair ratio matching for the single-ring and differential double-modulation three-rotor coaxial magnetic gear, the magnetic pole pair ratio is performed on the inner rotor and the outer rotor based on the magnetic pole pair ratio on the intermediate rotor.

10. A new energy vehicle hub motor, characterized in that: The invention comprises the single-ring and differential double-modulation three-rotor coaxial magnetic gear as described in any one of claims 1 to 9.

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