Dual rotor generator and wind power system

Abstract

The application discloses a double-rotor generator and a wind power generation system, and relates to the technical field of double-rotor generators. The double-rotor generator comprises a stator, an inner rotor and an outer rotor, the stator is provided with a first armature winding and a second armature winding; the inner rotor is located inside the stator; the outer rotor is located between the stator and the inner rotor; the stator, the first armature winding and the outer rotor are used for forming a permanent magnet synchronous generator part, and the stator, the second armature winding, the outer rotor and the inner rotor are used for forming a magnetic gear generator part; the outer rotor and the inner rotor rotate relative to the stator respectively, so that a synthetic magnetic field with a fundamental wave and a high-order harmonic wave can be formed in an outer air gap between the stator and the outer rotor, the magnetic field formed by the fundamental wave is used for power generation in cooperation with the first armature winding, and the magnetic field formed by the high-order harmonic wave is used for power generation in cooperation with the second armature winding.

Description

Technical Field

[0001] This application relates to the field of dual-rotor generator technology, and more particularly to a dual-rotor generator and a wind power generation system. Background Technology

[0002] With the increasing scarcity of fossil fuels and their growing environmental pollution, the use of wind power, a more economical and environmentally friendly alternative to fossil fuels for power generation, is becoming increasingly promising. In recent years, the rotor of a doubly-fed induction generator has been connected to an external frequency converter via slip rings. By controlling the voltage and frequency on the rotor side, independent control of the generator's active and reactive power output can be achieved.

[0003] In related technologies, this type of generator, when applied to wind power systems, improves power generation efficiency by adjusting the rotor current to adapt to different wind speeds. However, on the one hand, the generator's overall size is relatively large due to the inclusion of a brush structure. On the other hand, the windings being wound around an inner rotor cause significant cooling problems. Furthermore, the slip rings on the brushes increase the generator's overall unreliability and lead to high maintenance costs. Summary of the Invention

[0004] Embodiments of this application provide a dual-rotor generator and a wind power generation system to solve the problems of insufficiently compact structure and high maintenance costs of wind turbines in related technologies.

[0005] In a first aspect, embodiments of this application provide a dual-rotor generator for a wind power generation system. The dual-rotor generator includes a stator, an inner rotor, and an outer rotor. The stator is provided with a first armature winding and a second armature winding. The inner rotor is located inside the stator. The outer rotor is located between the stator and the inner rotor. The stator, the first armature winding, and the outer rotor are used to form a permanent magnet synchronous generator section. The stator, the second armature winding, the outer rotor, and the inner rotor are used to form a magnetic gear generator section. The outer rotor and the inner rotor rotate relative to the stator, such that a composite magnetic field with a fundamental wave and higher harmonics can be formed in the outer air gap between the stator and the outer rotor. The magnetic field formed by the fundamental wave cooperates with the first armature winding to generate electricity, and the magnetic field formed by the higher harmonics cooperates with the second armature winding to generate electricity. The harmonic order of the higher harmonics is m, where m is an odd number greater than 1.

[0006] In some embodiments, the magnetic gear generator section satisfies the following relationship: p w2 =|m×p ro -p ri |, where p w2 p is the number of pole pairs of the second armature winding; rop is the number of pole pairs of the outer rotor; ri The number of pole pairs of the inner rotor; the permanent magnet synchronous generator part satisfies the following relationship: p w1 =p ro In the formula, p w1 p is the number of pole pairs of the first armature winding. ro denoted as the number of pole pairs of the external rotor.

[0007] In some embodiments, the outer rotor rotates in the opposite direction to the inner rotor.

[0008] In some embodiments, the outer rotor includes: a plurality of iron cores, a plurality of tangential permanent magnets and a plurality of radial permanent magnets, wherein the iron cores are located between two adjacent tangential permanent magnets, the iron cores have at least one clearance opening, and a radial permanent magnet is provided at one of the clearance openings; the iron cores and the tangential permanent magnets are arranged at intervals; the plurality of iron cores, the plurality of tangential permanent magnets and the plurality of radial permanent magnets together form a ring-shaped structure.

[0009] In some embodiments, the iron core is block-shaped and has a fan-shaped profile in a cross section perpendicular to the axial direction of the outer rotor; the iron core includes an outer sidewall and an inner sidewall in the radial direction of the outer rotor, and the clearance opening is provided on the inner sidewall.

[0010] In some embodiments, an allowance opening is provided on the inner sidewall of one of the iron cores, and the number of iron cores is equal to the number of radial permanent magnets.

[0011] In some embodiments, the inner sidewall of one of the iron cores is provided with a plurality of clearance openings, the plurality of clearance openings are spaced apart and evenly arranged along the circumference of the outer rotor, and the number of radial permanent magnets is n times the number of the iron cores, where n is a positive integer greater than or equal to 2.

[0012] In some embodiments, the inner rotor is a modulated tooth structure, the inner rotor is the magnetic adjustment ring of the magnetic gear generator section, and the number of pole pairs of the inner rotor is equal to the number of teeth of the inner rotor.

[0013] In some embodiments, the stator includes a stator yoke and a plurality of stator teeth. The stator teeth are connected to the inner side of the stator yoke and extend toward the center of the stator yoke. The plurality of stator teeth are arranged circumferentially at intervals along the stator yoke. A stator slot is formed between two adjacent stator teeth. The side of the stator slot away from the stator yoke has an outer air gap. The first armature winding and the second armature winding are arranged in the stator slot.

[0014] Secondly, embodiments of this application also provide a wind power generation system, including: a first rotating shaft, a second rotating shaft, and a dual-rotor generator as described in the first aspect, wherein the outer rotor of the dual-rotor generator is connected to the second rotating shaft, and the inner rotor of the dual-rotor generator is connected to the first rotating shaft.

[0015] The dual-rotor generator provided in this application embodiment has an inner rotor and an outer rotor rotating relative to the stator, thereby forming a composite magnetic field in the outer air gap between the stator and the outer rotor. In other words, based on the structure of the dual-rotor generator, the composite magnetic field can be modulated using a high-order harmonic method in the magnetic gear generator section of the dual-rotor generator. This allows the fundamental magnetic field and high-order harmonic magnetic fields in the composite magnetic field to cooperate with the first armature winding and the second armature winding to generate electricity, respectively. This enables the permanent magnet synchronous generator section and the magnetic gear generator section to generate electricity independently. This not only allows the dual-rotor generator to integrate the permanent magnet synchronous generator section without the need for excitation windings and brushes, but also simplifies the structure, increases power, power density, and speed range. The magnetic gear generator unit boasts advantages such as wide coverage, contactless transmission, high reliability, low vibration and noise, and high efficiency. Furthermore, by employing a high-order harmonic modulation method, the magnetic gear generator unit achieves at least third-order harmonics in the synthesized magnetic field. This increases the number of pole pairs in the second armature winding, thereby improving the power generation efficiency of the dual-rotor generator. Moreover, the permanent magnet synchronous generator unit and the magnetic gear generator unit share the stator and outer rotor structure. Compared to the structure of doubly-fed induction generators in related technologies, the dual-rotor generator has a more compact structure and higher space utilization. Additionally, it eliminates the need for brushes, further reducing generator maintenance costs. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a partial structural schematic diagram of a wind power generation system in some embodiments of this application;

[0018] Figure 2 for Figure 1 A partial structural diagram from another perspective;

[0019] Figure 3 for Figure 1 A schematic diagram of the structure of a dual-rotor generator from one perspective;

[0020] Figure 4 for Figure 3 The front view;

[0021] Figure 5 This is a schematic diagram of the internal rotor structure in some embodiments of this application;

[0022] Figure 6 Comparison of local structures of the outer rotor for different harmonic orders;

[0023] Figure 7 The image shows the magnetomotive force waveform of the dual-rotor generator of this application.

[0024] Figure 8 The equivalent magnetic circuit diagram of the dual-rotor generator of this application is shown below;

[0025] Figure 9 This is a simulation comparison diagram showing the relationship between the position of the outer rotor and the back electromotive force when high-order harmonic current and fundamental current are respectively applied to the dual rotor generator in the embodiments of this application.

[0026] Figure 10 This is a simulation comparison diagram showing the relationship between harmonic order and back electromotive force when high-order harmonic current and fundamental current are respectively applied to the dual rotor generator in the embodiments of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 10. Stator; 11. Stator yoke; 12. Stator teeth; 13. Stator slot;

[0029] 20. Outer rotor; 21. Iron core; 211. Outer side wall; 212. Inner side wall; 22. Tangential permanent magnet; 23. Radial permanent magnet;

[0030] 30. Internal rotor;

[0031] 41. First armature winding; 42. Second armature winding;

[0032] 50. Outer air gap;

[0033] 100, First shaft; 110, First blade; 200, Second shaft; 210, Second blade; 300, Frame; 400, First bearing; 500, Second bearing. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "connection" and "joining" should be interpreted broadly, for example, as fixed connection, detachable connection, or integral connection; those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0037] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0038] With the increasing scarcity of fossil fuels and their growing environmental pollution, the use of wind power, a more economical and environmentally friendly alternative to fossil fuels for power generation, is becoming increasingly promising. In recent years, the rotor of a doubly-fed induction generator has been connected to an external frequency converter via slip rings. By controlling the voltage and frequency on the rotor side, independent control of the generator's active and reactive power output can be achieved.

[0039] In related technologies, this type of generator, when applied to wind power systems, improves power generation efficiency by adjusting the rotor current to adapt to different wind speeds. However, on the one hand, the generator's overall size is relatively large due to the inclusion of a brush structure. On the other hand, the windings being wound around an inner rotor cause significant cooling problems. Furthermore, the slip rings on the brushes increase the generator's overall unreliability and lead to high maintenance costs.

[0040] To address the aforementioned issues, this application provides a dual-rotor generator and a wind power generation system.

[0041] like Figures 1-4As shown, the dual-rotor generator includes a stator 10, an inner rotor 30, and an outer rotor 20. The stator 10 has a first armature winding 41 and a second armature winding 42. The inner rotor 30 is located inside the stator 10, and the outer rotor 20 is located between the stator 10 and the inner rotor 30. The stator 10, the first armature winding 41, and the outer rotor 20 form a permanent magnet synchronous generator section, while the stator 10, the second armature winding 42, the outer rotor 20, and the inner rotor 30 form a magnetic gear generator section. The outer rotor 20 and the inner rotor 30 rotate relative to the stator 10, thereby forming a composite magnetic field with fundamental and higher harmonics in the outer air gap 50 between the stator 10 and the outer rotor 20. The magnetic field formed by the fundamental wave works in conjunction with the first armature winding 41 to generate electricity, and the magnetic field formed by the higher harmonics works in conjunction with the second armature winding 42 to generate electricity. That is, the permanent magnet synchronous generator section and the magnetic gear generator section can operate independently to generate electricity.

[0042] It should be noted that the harmonic order of the above higher harmonics is m, where m is an odd number greater than 1, specifically m = 3, 5, 7, ...

[0043] The fundamental frequency mentioned above refers to the first harmonic. Higher harmonics refer to the third harmonic, fifth harmonic, and so on.

[0044] The aforementioned inner rotor 30 is the adjusting ring of the magnetic gear generator section. A conventional magnetic gear generator includes a first outer rotor, a first inner rotor, and a first adjusting ring. The first outer rotor and second inner rotor are distinguishable from the outer rotor and inner rotor in this application. The first adjusting ring is distinguishable from the adjusting ring of the magnetic gear generator in this application, i.e., the inner rotor. The first adjusting ring is located between the first outer rotor 20 and the first inner rotor 30 and is fixed. The magnetic field generated by the windings on the stator of the magnetic gear generator rotates. Compared to the structure of a conventional magnetic gear generator, the main difference in the magnetic gear generator section of this application lies in the structure of the adjusting ring, specifically, the inner rotor 30 in this application is rotatable and is located on the innermost side; that is, the adjusting ring is rotatable. With the above settings, a brushless design is achieved compared to conventional magnetic gear generators. This not only makes the magnetic field generated by the higher harmonics in the synthetic magnetic field larger and the rotation speed faster, but also results in a larger output power for the wind power generation system. The internal rotor 30 structure design is more flexible and can be adjusted according to different application requirements. In addition, the structure of the magnetic gear generator is more compact, which can effectively utilize space.

[0045] The aforementioned permanent magnet synchronous generator section has a rotor permanent magnet structure, which has a larger torque than the stator 10 permanent magnet structure.

[0046] Based on the structure of this dual-rotor generator, a high-order harmonic modulation method can be used to modulate the magnetic gear generator section, enabling the generation of high-order harmonic magnetic fields in the synthesized magnetic field. In other words, by combining the high-order harmonic modulation method with the structure of this dual-rotor generator, not only can high-order harmonic magnetic fields be generated, but the order of the high-order harmonics in the synthesized magnetic field can also be adjusted. Thus, by increasing the order m of the high-order harmonics in the synthesized magnetic field, the output power generated at the second armature winding 42 can be increased. Specifically, by adjusting parameters such as the number of pole pairs of the stator 10, inner rotor 30, and outer rotor 20, and combining this with the high-order harmonic modulation method, synthesized magnetic fields with different harmonic combinations can be obtained to meet different scenario requirements.

[0047] The dual-rotor generator provided in this application embodiment has an inner rotor 30 and an outer rotor 20 rotating relative to the stator 10, allowing a composite magnetic field to be formed in the outer air gap 50 between the stator 10 and the outer rotor 20. In other words, based on the structure of the dual-rotor generator, the composite magnetic field can be modulated using a high-order harmonic method in the magnetic gear generator section of the dual-rotor generator. This allows the fundamental magnetic field and the high-order harmonic magnetic field in the composite magnetic field to cooperate with the first armature winding 41 and the second armature winding 42 to generate electricity, enabling the permanent magnet synchronous generator section and the magnetic gear generator section to generate electricity independently. This not only allows the dual-rotor generator to integrate the permanent magnet synchronous generator section without the need for excitation windings and brushes, but also simplifies the structure, increases power, and improves power density. The magnetic gear generator unit boasts advantages such as high speed and wide speed range, as well as the contactless transmission, high reliability, low vibration and noise, and high efficiency of the magnetic gear generator section. Furthermore, by employing a high-order harmonic modulation method, the order of the high-order harmonics in the synthetic magnetic field is at least third. This increases the number of pole pairs in the second armature winding 42, thereby improving the power generation efficiency of the dual-rotor generator. Moreover, the permanent magnet synchronous generator section and the magnetic gear generator section share the structure of the stator 10 and the outer rotor 20. Compared to the structure of doubly-fed induction generators in related technologies, the dual-rotor generator has a more compact structure and higher space utilization. Furthermore, it eliminates the need for brushes, further reducing generator maintenance costs. It should be noted that the high-order harmonic modulation method used in the magnetic gear generator section primarily alters the high-order harmonic components of the magnetic field in the outer air gap 50 by adjusting the structure of the magnetic adjustment ring (i.e., the inner rotor 30 in this application), such as its order, thereby increasing torque density and thus torque output. Specific details of the high-order harmonic modulation method are provided later.

[0048] This dual-rotor generator can be used, but is not limited to, in wind power generation systems. The following explanation uses the application of a dual-rotor generator in a wind power generation system as an example.

[0049] like Figure 1 and Figure 2As shown, the wind power generation system includes a first shaft 100, a second shaft 200, and a dual-rotor generator. The outer rotor 20 of the dual-rotor generator is connected to the second shaft 200, and the inner rotor 30 of the dual-rotor generator is connected to the first shaft 100.

[0050] Specifically, such as Figure 2 and Figure 4 As shown, the wind power generation system also includes a frame 300, a first blade 110, a second blade 210, a first bearing 400, and a second bearing 500. The stator 10 is fixed to the frame 300. One end of the first shaft 100 is fixed to the inner rotor 30, and the other end of the first shaft 100 is connected to the first blade 110. Simultaneously, the first shaft 100 is rotatably connected to the outer rotor 20 via the first bearing 400. One end of the second shaft 200 is fixed to the outer rotor 20, and the other end of the second shaft 200 is connected to the second blade 210. Simultaneously, the second shaft 200 is connected to the frame 300 via the second bearing 500. The rotor is rotatably connected. Under the action of wind, the first blade 110 can drive the inner rotor 30 to rotate through the first rotating shaft 100, and the second blade 210 can drive the outer rotor 20 to rotate through the second rotating shaft 200. In the structure of the dual rotor generator, a high-order harmonic modulation method is adopted. That is, the dual rotor generator is combined with the high-order harmonic modulation method so that a composite magnetic field with fundamental wave and high-order harmonics can be formed in the outer air gap 50 between the stator 10 and the outer rotor 20. The magnetic field formed by the fundamental wave cooperates with the first armature winding 41 to generate electricity, and the magnetic field formed by the high-order harmonics cooperates with the second armature winding 42 to generate electricity.

[0051] During the operation of the dual-rotor generator, the stator 10 is relatively fixed, while the outer rotor 20 and the inner rotor 30 can rotate around the central axis of the stator 10. That is, the inner rotor 30 and the outer rotor 20 are coaxially arranged. The rotation directions of the inner rotor 30 and the outer rotor 20 can be the same or opposite, and no specific limitation is made here.

[0052] However, when the outer rotor 20 and the inner rotor 30 rotate in opposite directions, that is, when the inner rotor 30 and the outer rotor 20 rotate in opposite directions, the rotational speed of the resultant magnetic field will be higher than when the inner rotor 30 and the outer rotor 20 rotate in the same direction. In other words, the frequency generated in the armature winding will be higher.

[0053] like Figure 3 and Figure 4As shown, the stator 10 includes a stator yoke 11 and a plurality of stator teeth 12. The stator teeth 12 are connected to the inner side of the stator yoke 11 and extend toward the center of the stator yoke 11. The plurality of stator teeth 12 are arranged at intervals along the circumference of the stator yoke 11. A stator slot 13 is formed between two adjacent stator teeth 12. The side of the stator slot 13 away from the stator yoke 11 has an outer air gap 50. The first armature winding 41 and the second armature winding 42 are arranged in the stator slot 13.

[0054] By arranging the first armature winding 41 and the second armature winding 42 in the stator slot 13, the space between the stator yoke 11 and the outer rotor 20 in the stator 10 can be rationally utilized, thereby further improving the space utilization rate of the dual rotor generator.

[0055] like Figure 3 and Figure 5 As shown, the inner rotor 30 has a modulating tooth structure, meaning its outline is gear-shaped. The inner rotor 30 serves as the adjusting ring of the magnetic gear generator, and the number of pole pairs of the inner rotor 30 is equal to the number of teeth. This design simplifies the structure of the adjusting ring in the magnetic gear generator and allows for more flexible design. Specifically, different numbers of pole pairs can be obtained by changing the number of teeth in the inner rotor 30, making it highly practical.

[0056] In the design of a dual-rotor generator, especially for a geared generator section, the structure of the outer rotor 20 is extremely important. The outer rotor 20 is located between the stator 10 and the inner rotor 30, and is primarily a circular ring structure. For example... Figure 1 As shown, the outer rotor 20 includes: multiple iron cores 21, multiple tangential permanent magnets 22, and multiple radial permanent magnets 23. The iron cores 21 are located between two adjacent tangential permanent magnets 22, and each iron core 21 has at least one clearance opening. A radial permanent magnet 23 is located at each clearance opening. The iron cores 21 and the tangential permanent magnets 22 are arranged at intervals. The multiple iron cores 21, multiple tangential permanent magnets 22, and multiple radial permanent magnets 23 together form a ring-shaped structure. For example, as... Figure 4 As shown, the outer rotor 20 is a ring-shaped structure formed by 22 (11 pairs) iron cores 21, 22 tangential permanent magnets 22 and 22 radial permanent magnets 23.

[0057] The shape and size of the clearance opening on the radial permanent magnet 23 of the iron core 21 must be the same as the shape and size of the clearance opening on the corresponding iron core 21.

[0058] In a conventional magnetic gear generator, the central element is a magnetic adjustment ring (relative to the outer rotor 20 in this application). The magnetic adjustment ring includes multiple iron cores 21 and multiple tangential permanent magnets 22, with the iron cores 21 located between two adjacent tangential permanent magnets 22. Such a magnetic gear generator can only generate a fundamental frequency.

[0059] The outer rotor 20 in this application, by adding a radial permanent magnet 23 between two adjacent tangential permanent magnets 22, enables not only the fundamental wave to be generated in the synthetic magnetic field, but also higher harmonics, thus providing a structural basis for the application of higher harmonic methods.

[0060] like Figure 4 As shown, the core 21 is block-shaped and its outline in the cross section perpendicular to the axial direction of the outer rotor 20 is fan-shaped; the core 21 includes an outer side wall 211 and an inner side wall 212 in the radial direction of the outer rotor 20, and the inner side wall 212 is provided with a clearance opening.

[0061] In the design of the outer rotor 20, the clearance opening on the iron core 21 is to face the magnetic adjustment ring. Since the inner rotor 30 (relative to the magnetic adjustment ring) is located inside the outer rotor 20 in this application, the clearance opening is set on the inner sidewall 212 of the iron core 21, which reduces the magnetic flux path.

[0062] During the design of the outer rotor 20, one or more clearance openings can be set on an iron core 21. A tangential permanent magnet 22 is set in each clearance opening. The rotational speed of the composite magnetic field can be adjusted by adjusting the current in the second armature winding 42. The torque of the composite magnetic field can be adjusted by adjusting the first armature winding 41 to meet different application scenarios.

[0063] During the design process of the first armature winding 41 and the second armature winding 42, the number of pole pairs p of the first armature winding 41 is... w1 The number of pole pairs p of the second armature winding 42 w2 This is quite important; it needs to satisfy the following relationship. Specifically, the magnetic gear generator does not satisfy the following relationship: p w2 =|m×p ro -p ri |, where p w2 p is the number of pole pairs of the second armature winding 42; ro p is the number of pole pairs of the outer rotor 20; ri The number of pole pairs of the inner rotor 30; the permanent magnet synchronous generator does not satisfy the relationship: p w1 =p ro In the formula, p w1 p is the number of pole pairs of the first armature winding 41. ro The number of pole pairs of the outer rotor 20.

[0064] like Figure 4 and Figure 6As shown, in some embodiments, an inner wall 212 of an iron core 21 is provided with a clearance opening, and the number of iron cores 21 is equal to the number of radial permanent magnets 23. That is, two adjacent tangential permanent magnets 22 are connected by an iron core 21, and a radial permanent magnet 23 is provided at the clearance opening of each iron core 21. The total number of radial permanent magnets 23 is equal to the total number of clearance openings. Therefore, the number of clearance openings on an iron core 21 is also the number of radial permanent magnets 23 provided on an iron core 21.

[0065] like Figure 6 The diagram shows the correspondence between the core 21 and the radial permanent magnet 23 between two adjacent tangential permanent magnets 22 of the outer rotor 20 when m is equal to 3, 5 and 7 respectively.

[0066] from Figure 6 It can be seen that if the third harmonic is required (m=3), then n=1; if the fifth harmonic is required (m=5), then n=2; if the seventh harmonic is required (m=7), then n=3, and so on. Specifically:

[0067] When m = 3, n = 1, and at this time, corresponding to p ro =11; p ri =31; then, p w2 =2, p w1 =11.

[0068] When m = 5, n = 2, and at this time, corresponding to p ro =11; p ri =53; then, p w2 =2, p w1 =11.

[0069] When m = 7, n = 3, and at this time, corresponding to p ro =11; p ri =75; then, p w2 =2, p w1 =11.

[0070] In addition, in other embodiments, such as Figure 6 As shown, the inner wall 212 of an iron core 21 is provided with multiple clearance openings. These clearance openings are spaced apart and evenly distributed along the circumference of the outer rotor 20. The number of radial permanent magnets 23 is n times the number of iron cores 21, where n is a positive integer greater than or equal to 2, specifically n = 2, 3, 4, ... Since the total number of radial permanent magnets 23 is equal to the total number of clearance openings, the number of clearance openings on an iron core 21 corresponds to the number of radial permanent magnets 23 disposed on the iron core 21.

[0071] By changing the number of clearance openings on a core 21, the ratio n of the number of radial permanent magnets 23 to the number of cores 21 can be obtained through the higher harmonic order m. This determines the number of radial permanent magnets 23 placed between two adjacent tangential permanent magnets 22 and the number of clearance openings on the core 21, thus providing different structural foundations for obtaining different higher harmonics. Furthermore, this demonstrates that the dual-rotor generator has a wide range of applications and can meet the requirements of various application scenarios.

[0072] The following explanation uses m=3 and n=1 as an example.

[0073] Based on the structure of the outer rotor 20 and the parameters described above, a third harmonic can be generated. The magnetomotive force waveform of the dual-rotor generator is as follows: Figure 6 As shown. Thus, compared to a magnetic field that can only generate the fundamental wave, i.e., the order m of the higher harmonics is 3, the magnetic field generated by the third harmonic is stronger, and the torque of the synthesized magnetic field is greater when modulated using the higher harmonic current.

[0074] The detailed derivation process of the higher harmonic modulation method is as follows:

[0075] The magnetomotive force generated by the inner air gap between the outer rotor 20 and the inner rotor 30 can be expressed as:

[0076]

[0077] In the formula, p ro Ω represents the number of pole pairs of the outer rotor 20, and also the number of pole pairs of the radial and tangential permanent magnets 22 on the outer rotor 20. ro The external rotor operates at a speed of 20. For the initial angle of the outer rotor 20, F in The magnetomotive force amplitude of the nth harmonic is given.

[0078] according to Figure 7 The magnetomotive force waveform shown can be expressed as follows by performing Fourier decomposition on the magnetomotive force in formula (1):

[0079]

[0080] Figure 8 The equivalent magnetic circuit of the dual-rotor generator is shown, based on Kirchhoff's first law, with inflow and outflow... Figure 8 The magnetic flux of node A in the diagram satisfies the following relationship:

[0081]

[0082] Figure 8 In the middle, R o R ic and R imThe magnetic reluctance R is the magnetic reluctance of the inner air gap under the outer air gap 50, the inner air gap under the iron core 21, and the inner air gap under the permanent magnet section. s and R r The magnetic reluctance F is the reluctance of the tangential permanent magnet 22 and the radial permanent magnet 23. s and F r It is the magnetomotive force of the tangential permanent magnet 22 and the radial permanent magnet 23.

[0083] At the same time, based on Kirchhoff's second law, Figure 8 The relationship between loops B and C in the equation can be expressed as:

[0084]

[0085] 2F mo -2F ic =0 (5)

[0086] Based on formulas (3)-(5), the expressions for different magnetomotive forces can be derived as follows:

[0087]

[0088] In the formula, R sm It is the sum of the equivalent magnetic reluctance of the motor.

[0089] When core saturation is ignored, the back EMF of the motor can be expressed as:

[0090]

[0091] In the formula, D is the diameter of the outer air gap circumference, and N... t L represents the number of motor turns. stk k is the axial length of the motor. w B(n,l) and B(n,l) are the motor winding factor and magnetic flux density, respectively. Ω(n,l) is the motor speed, satisfying the following relationship:

[0092]

[0093] In the formula, Ω ro Ω ri The rotational speeds of the outer rotor 20 and the inner rotor 30 are respectively, p ri denoted by 30 pole pairs for the inner rotor. m represents the harmonic order of the motor.

[0094] As can be seen from equation (9), the motor speed Ω after high-order harmonic modulation is w3 The motor speed Ω is greater than the fundamental frequency modulation speed. w1 Furthermore, based on formula (9), when the two rotors of the motor rotate in opposite directions, i.e., when the dual-rotor counter-rotation technology is adopted, the rotational speed Ω of the modulated synthetic magnetic field is... wm，It is larger than a single-rotor motor, thus achieving the purpose of speed expansion.

[0095] The ratio of the air gap magnetic flux density modulated by higher harmonics and the fundamental frequency can be expressed as:

[0096]

[0097] In the formula, F3 and F1 are the magnetomotive forces of the motor after modulation by higher harmonics and fundamental wave, respectively. Λ1 is the air gap permeability of the motor.

[0098] Therefore, combining formulas (9) and (10), it can be seen that the back EMF after higher harmonic modulation is greater, and the corresponding output torque is also greater.

[0099] In a finite element simulation case, the back electromotive force of the outer rotor 20 in a dual-rotor generator is simulated by applying high-order harmonic current and fundamental current respectively. Figure 9 and Figure 10 As shown, after the high-order harmonic current is applied, the back EMF amplitude of the generator is 65V, while the back EMF of the dual rotor generator is 52V when the traditional fundamental frequency modulation method is used. It can be seen that the back EMF of the dual rotor generator proposed in this invention is increased by as much as 42% after the high-order harmonic modulation method is used.

[0100] The output torque is compared between the dual-rotor generator of this application and generators in related technologies through simulation, as shown in Table 1 below.

[0101] Table 1 Comparison of output torque for different generator harmonic modulation methods

[0102] Torque (higher harmonic modulation) Torque (fundamental frequency modulation) Permanent magnet synchronous section 21 Nm 22Nm Magnetic gear section 25Nm 18Nm comprehensive 46Nm 40Nm

[0103] As can be seen from Table 1, when the current of the first armature winding 41 remains unchanged, the torque of the magnetic gear generator after high-order harmonic modulation is higher than that of the traditional fundamental wave modulation method. Therefore, the overall output torque of the dual rotor generator is greater, thus effectively proving the expected design results of the dual rotor generator.

[0104] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dual-rotor generator for use in a wind power generation system, characterized in that, The dual-rotor generator includes: Stator (10), wherein a first armature winding (41) and a second armature winding (42) are provided on the stator (10); The inner rotor (30) is located inside the stator (10); The outer rotor (20) is located between the stator (10) and the inner rotor (30); The stator (10), the first armature winding (41) and the outer rotor (20) are used to form a permanent magnet synchronous generator section, and the stator (10), the second armature winding (42), the outer rotor (20) and the inner rotor (30) are used to form a magnetic gear generator section; The outer rotor (20) and the inner rotor (30) rotate relative to the stator (10) respectively, so that a composite magnetic field with a fundamental wave and higher harmonics can be formed in the outer air gap (50) between the stator (10) and the outer rotor (20). The magnetic field formed by the fundamental wave cooperates with the first armature winding (41) to generate electricity, and the magnetic field formed by the higher harmonics cooperates with the second armature winding (42) to generate electricity. The harmonic order of the higher harmonics is m, where m is an odd number greater than 1.

2. The dual-rotor generator according to claim 1, characterized in that, The magnetic gear generator section satisfies the following relationship: p w2 =|m×p ro -p ri |, where p w2 p is the number of pole pairs of the second armature winding (42); ro p is the number of pole pairs of the outer rotor (20); ri The number of pole pairs of the inner rotor (30); The permanent magnet synchronous generator part satisfies the following relationship: p w1 =p ro In the formula, p w1 p is the number of pole pairs of the first armature winding (41). ro is the number of pole pairs of the outer rotor (20).

3. The dual-rotor generator according to claim 1, characterized in that, The outer rotor (20) rotates in the opposite direction to the inner rotor (30).

4. The dual-rotor generator according to claim 1, characterized in that, The outer rotor (20) includes: multiple iron cores (21), multiple tangential permanent magnets (22) and multiple radial permanent magnets (23). The iron cores (21) are located between two adjacent tangential permanent magnets (22). The iron cores (21) have at least one clearance opening, and a radial permanent magnet (23) is provided at one of the clearance openings. The iron core (21) and the tangential permanent magnet (22) are arranged at intervals; Multiple iron cores (21), multiple tangential permanent magnets (22) and multiple radial permanent magnets (23) are arranged together to form a ring-shaped structure.

5. The dual-rotor generator according to claim 4, characterized in that, The iron core (21) is block-shaped and has a fan-shaped profile in a cross section perpendicular to the axial direction of the outer rotor (20); the iron core (21) includes an outer sidewall (211) and an inner sidewall (212) in the radial direction of the outer rotor (20), and the inner sidewall (212) is provided with the clearance opening.

6. The dual-rotor generator according to claim 5, characterized in that, The inner sidewall (212) of one of the iron cores (21) is provided with a clearance opening, and the number of iron cores (21) is equal to the number of radial permanent magnets (23).

7. The dual-rotor generator according to claim 5, characterized in that, The inner sidewall (212) of one of the iron cores (21) is provided with a plurality of clearance openings, which are spaced apart and evenly arranged along the circumference of the outer rotor (20). The number of radial permanent magnets (23) is n times the number of iron cores (21), where n is a positive integer greater than or equal to 2.

8. The dual-rotor generator according to any one of claims 1 to 7, characterized in that, The inner rotor (30) is a modulating tooth structure, the inner rotor (30) is the magnetic adjustment ring of the magnetic gear generator part, and the number of pole pairs of the inner rotor (30) is equal to the number of teeth of the inner rotor (30).

9. The dual-rotor generator according to any one of claims 1 to 7, characterized in that, The stator (10) includes a stator yoke (11) and a plurality of stator teeth (12). The stator teeth (12) are connected to the inner side of the stator yoke (11) and extend toward the center of the stator yoke (11). The plurality of stator teeth (12) are arranged circumferentially at intervals along the stator yoke (11). A stator slot (13) is formed between two adjacent stator teeth (12). The stator slot (13) has an outer air gap (50) on the side away from the stator yoke (11). The first armature winding (41) and the second armature winding (42) are arranged in the stator slot (13).

10. A wind power generation system, characterized in that, include: First pivot (100), Second pivot (200), The dual-rotor generator as described in any one of claims 1 to 9, wherein the outer rotor (20) of the dual-rotor generator is connected to the second rotating shaft (200), and the inner rotor (30) of the dual-rotor generator is connected to the first rotating shaft (100).

Images