Axial flux single tooth winding concentrated winding multi-torque double rotor low speed direct drive generator

Abstract

The application discloses a kind of axial flux single-tooth winding concentrated winding multi-torque double-rotor low-speed direct-drive generator, including stator, first rotor and second rotor, wherein, stator is located between first rotor and second rotor, the structure of first rotor and second rotor is same, and first rotor and second rotor are about stator symmetric and coaxial installation, stator and first rotor and second rotor between have air gap, this generator has the characteristics of high power and light weight.

Description

Technical Field

[0001] This invention belongs to the field of wind power permanent magnet generators and relates to a low-speed direct-drive generator with axial flux single-tooth winding concentrated winding and multiple torque dual rotors. Background Technology

[0002] As the problems caused by global warming become increasingly severe, the importance of clean energy is growing. In recent years, wind power has become the world's fastest-growing source of electricity. Wind power is divided into onshore and offshore wind power. Due to the limited onshore wind and land resources, offshore wind resources are more abundant and stable, leading to a significant increase in the scale of offshore wind power generation. In recent years, with the continuous development of offshore wind power, the distance between offshore wind turbines and the shore has also increased, making traditional power transmission methods insufficient. The frequency-division transmission system proposed by Academician Wang Xifan can adapt to long-distance offshore power transmission by reducing the transmission frequency, making it more suitable for offshore wind power generation.

[0003] Permanent magnet direct-drive wind turbines eliminate the need for gearboxes and other transmission structures, resulting in a simple mechanical structure and significant advantages such as high efficiency, high reliability, convenient maintenance, minimal impact on the power grid, and simple control. For offshore wind farms, combining low-speed direct-drive permanent magnet wind turbines with frequency-division transmission systems offers even greater advantages. Generally, direct-drive wind turbines are larger and heavier than ordinary permanent magnet synchronous wind turbines. Frequency-division transmission systems use AC power at a frequency of 50 / 3Hz, lower than the conventional AC frequency of 50Hz. This reduction in frequency leads to a further increase in the size of the generator, posing new challenges to the manufacturing, transportation, installation, and maintenance of wind turbines.

[0004] Therefore, researching high-power lightweight generators suitable for offshore frequency-division transmission systems will benefit the development of the offshore wind power industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator, which has the characteristics of high power and lightweight.

[0006] To achieve the above objectives, the axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator of the present invention includes a stator, a first rotor, and a second rotor. The stator is located between the first rotor and the second rotor. The first rotor and the second rotor have the same structure and are symmetrical about the stator and coaxially mounted. There is an air gap between the stator and both the first rotor and the second rotor.

[0007] On the first rotor, several first rotor cores are evenly arranged circumferentially on the surface facing the stator. A first rotor unit sector-shaped slot is formed between adjacent first rotor cores. On the second rotor, several second rotor cores are evenly arranged circumferentially on the surface facing the stator. A second rotor unit sector-shaped slot is formed between adjacent second rotor cores. Each first rotor unit sector-shaped slot contains a first rotor permanent magnet, and each second rotor unit sector-shaped slot contains a second rotor permanent magnet.

[0008] The stator has a circular ring structure and includes stator teeth, stator armature winding, lower stator Halbach permanent magnet array and upper stator Halbach permanent magnet array. The stator teeth are evenly arranged along the circumference, and parallel slots of stator units are formed between adjacent stator teeth. The stator armature winding adopts a single-tooth concentrated winding structure and is wound on the stator teeth. The lower stator Halbach permanent magnet array and the upper stator Halbach permanent magnet array are evenly distributed at the slot opening positions on both sides of the parallel slots of the stator unit with the stator axis as the center, and are located on both sides of the stator armature winding.

[0009] Both the lower stator Halbach permanent magnet array and the upper stator Halbach permanent magnet array include a first stator permanent magnet, a second stator permanent magnet, and a third stator permanent magnet arranged sequentially.

[0010] The magnetization direction of the second stator permanent magnet is along the axial direction.

[0011] The polarity of the second stator permanent magnet is the same as that of the second rotor permanent magnet.

[0012] The magnetization direction of both the first and third stator permanent magnets is radial along the circumference, and the magnetization directions are opposite to each other.

[0013] Both the first rotor permanent magnet and the second rotor permanent magnet are magnetized along the axial direction and have the same polarity. The first rotor permanent magnet and the rotor teeth of the first rotor core form an alternating pole structure, and the second rotor permanent magnet and the rotor teeth of the second rotor core form an alternating pole structure.

[0014] The number of sector slots in the first rotor unit and the number of sector slots in the second rotor unit are both half the number of pole pairs in the stator armature winding.

[0015] The present invention has the following beneficial effects:

[0016] The axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator of the present invention adopts an axial flux dual-rotor structure in specific operation. It adopts the magnetic field modulation principle, resulting in high torque density. The motor adopts an axial flux structure, and the large working air gap area between the stator and rotor helps to generate large electromagnetic torque. The motor adopts a dual-rotor structure, and through clever magnetic circuit design, the yoke of the stator is eliminated, further improving the torque density of the motor and meeting the requirements of high power and lightweight.

[0017] Furthermore, permanent magnets are installed between the stator teeth and in the rotor core grooves. Three-phase AC current is supplied to the stator armature winding. During normal operation, the stator permanent magnets and rotor permanent magnets simultaneously provide mechanical output torque and are superimposed, further improving the torque density. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a waterfall diagram of the overall structure of the present invention;

[0020] Figure 3 This is a partial structural waterfall diagram of the present invention;

[0021] Figure 4 This is an exploded view of a portion of the rotor structure of the present invention;

[0022] Figure 5 This is an exploded view of a partial stator structure of the present invention;

[0023] Figure 6 This is a schematic diagram of the unit stator permanent magnet structure of the present invention;

[0024] Figure 7 This is a schematic diagram of the magnetization direction of the permanent magnet of the present invention.

[0025] Wherein, 1 is the first rotor, 2 is the stator, 3 is the second rotor, 4 is the first rotor core, 5 is the first rotor permanent magnet, 6 is the second rotor core, 7 is the second rotor permanent magnet, 8 is the stator tooth, 9 is the stator armature winding, 10 is the lower stator Halbach permanent magnet array, 10-1 is the first stator permanent magnet, 10-2 is the second stator permanent magnet, 10-3 is the third stator permanent magnet, and 11 is the upper stator Halbach permanent magnet array. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0027] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0028] refer to Figures 1 to 6 The axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct drive generator of the present invention includes a stator 2, a first rotor 1 and a second rotor 3, wherein the stator 2 is located between the first rotor 1 and the second rotor 3, the first rotor 1 and the second rotor 3 have the same structure, and the first rotor 1 and the second rotor 3 are symmetrically and coaxially mounted about the stator 2, and there is an air gap between the stator 2 and the first rotor 1 and the second rotor 3.

[0029] On the surface of the first rotor 11 facing the stator 2, a plurality of first rotor cores 4 are uniformly arranged circumferentially. A first rotor unit sector slot is formed between adjacent first rotor cores 4. On the surface of the second rotor 3 facing the stator 2, a plurality of second rotor cores 6 are uniformly arranged circumferentially. A second rotor unit sector slot is formed between adjacent second rotor cores 6. A first rotor permanent magnet 5 is provided in each first rotor unit sector slot, and a second rotor permanent magnet 7 is provided in each second rotor unit sector slot. The number of first rotor unit sector slots and the number of second rotor unit sector slots are both half the number of pole pairs of the stator armature winding 9.

[0030] The stator 2 has a circular ring structure and includes stator teeth 8, stator armature winding 9, lower stator Halbach permanent magnet array 10, and upper stator Halbach permanent magnet array 11. The stator teeth 8 are evenly arranged along the circumference, and parallel slots of stator units are formed between adjacent stator teeth 8. The stator armature winding 9 is wound on the stator teeth 8 using a single-tooth concentrated winding structure. The lower stator Halbach permanent magnet array 10 and the upper stator Halbach permanent magnet array 11 are evenly distributed at the slot openings on both sides of the parallel slots of the stator units, with the axis of the stator 2 as the center, and are located on both sides of the stator armature winding 9.

[0031] Both the lower stator Halbach permanent magnet array 10 and the upper stator Halbach permanent magnet array 11 include a first stator permanent magnet 10-1, a second stator permanent magnet 10-2, and a third stator permanent magnet 10-3, which are distributed sequentially.

[0032] like Figure 7 As shown, the solid arrows indicate the magnetization direction of the stator permanent magnet and the rotor permanent magnet. The first rotor permanent magnet 5 and the second rotor permanent magnet 7 are both magnetized along the axial direction and have the same polarity. The first rotor permanent magnet 5 and the rotor teeth of the first rotor core 4 form an alternating pole structure, and the second rotor permanent magnet 7 and the rotor teeth of the second rotor core 6 form an alternating pole structure.

[0033] Taking the lower stator Halbach permanent magnet array 10 as an example, the magnetization direction of the stator permanent magnet is as follows: the magnetization direction of the second stator permanent magnet 10-2 is along the axial direction, and the polarity of the second stator permanent magnet 10-2 is the same as that of the second rotor permanent magnet 7; the magnetization direction of the first stator permanent magnet 10-1 and the third stator permanent magnet 10-3 is both radial along the circumferential direction, and the magnetization directions are opposite to each other, with the magnetization angle θ between 0 and 90 degrees.

[0034] The number of pole pairs of stator armature winding 9 is P sac After a three-phase symmetrical alternating current is applied, a pole pair number of P is formed. sac The stator principal rotating magnetomotive force and the number of pole pairs P of the unmodulated rotating magnetic field generated by a permanent magnet on a rotor. rf They are identical, meaning they satisfy the following relationship: their interaction produces a conventional torque component T. c ;

[0035] P sac =P rf

[0036] When a three-phase symmetrical alternating current is applied to stator armature winding 9, it forms a magnetic pole pair with a number of P. sah The harmonic rotating magnetomotive force, when the number of pole pairs P of the permanent magnets on a rotor rf and stator teeth 8 N sWhen the following relationship is satisfied, the magnetic field generated by the rotor permanent magnet is modulated by the magnetic wave formed by the stator teeth 8, which will produce a rotor permanent magnet magnetic field modulation component. This modulation component interacts with the corresponding harmonic rotating magnetomotive force component generated by the stator armature winding 9 to produce a modulation torque component T. m1 .

[0037] p sah =|iP rf ±jN s |

[0038] Where i and j are integers.

[0039] When the number of pole pairs P of the stator permanent magnet sf The number of teeth N of a rotor r When the following formula is satisfied, the magnetic field generated by the stator permanent magnet is modulated by the magnetic wave formed by the rotor teeth, resulting in a stator permanent magnet magnetic field modulation component. This modulation component interacts with the corresponding harmonic rotating magnetomotive force component generated by the stator armature winding 9 to produce a modulation torque component T. m2 .

[0040] p sah =|kP sf ±lN r |

[0041] Where k and l are integers.

[0042] The above analysis shows that when the motor parameters are selected appropriately, three parts of torque will be generated. First, the rotating magnetic field generated by the unmodulated rotor permanent magnet interacts with the main rotating magnetic field generated by the AC component of the stator armature winding 9 to generate torque. Second, the rotating magnetic field modulated by the rotor permanent magnet through the stator teeth 8 interacts with the harmonic rotating magnetic field generated by the AC component of the stator armature winding 9 to generate torque. Third, the rotating magnetic field modulated by the stator permanent magnet through the rotor teeth interacts with the harmonic rotating magnetic field generated by the AC component of the stator armature winding 9 to generate torque. When the three parts of torque act on the rotor in the same direction, the combined electromagnetic torque is the largest. For example, the number of slots and pole pairs of the stator 2 and one rotor that satisfy the above three relationships are shown in Table 1.

[0043] Table 1

[0044]

[0045] The motor consists of 10 unit motors, and each unit motor also satisfies all the above relationships. The matching relationship between the number of slots and pole pairs of the stator 2 and one rotor of the unit motor (1 / 10 model) is shown in Table 2.

[0046] Table 2

[0047]

[0048] The number of stator slots N s and the number of slots N of a rotor r satisfy:

[0049] N s =k1m s

[0050] N r =P rf

[0051] Where k1 is an integer, m s The stator armature winding has 9 AC phases.

[0052] All other slot-pole combinations that satisfy the above five formulas and conform to the principles described in this invention are within the scope of protection of this patent and will not be listed here. Furthermore, taking the axial flux motor model as an example, motors conforming to the principles described in this patent, including but not limited to radial magnetic field motors and linear motors, are within the scope of protection of this patent.

[0053] Example 1

[0054] refer to Figure 3 The unit motor has 12 / 7 slots in the stator and rotor. After AC is applied to the stator armature winding 9, it generates a 7-pole main rotating magnetomotive force, as well as 5-pole, 17-pole, and 19-pole harmonic rotating magnetomotive forces. The rotor permanent magnet on one rotor generates a 7-pole rotating magnetic field without modulation, which couples with the main rotating magnetic field generated by the stator armature winding 9 to produce the first torque component. The rotor permanent magnet forms a 5-pole and 19-pole rotating magnetic field through the stator teeth 8, which couples with the 5-pole and 19-pole harmonic rotating magnetic fields generated by the stator armature winding 9 to produce the second torque component. The permanent magnet on one side of the stator 2 has 12 pole pairs, which form a 5-pole and 19-pole rotating magnetic field through the rotor teeth modulation, which couples with the 5-pole and 19-pole harmonic rotating magnetic fields generated by the stator armature winding 9 to produce the third torque component. When the three torque components act on the rotor in the same direction, the combined electromagnetic torque is the maximum.

[0055] This invention improves the motor structure by adopting a dual permanent magnet, dual rotor, and axial flux structure for both stator and rotor, which can generate multiple electromagnetic torques. Furthermore, through ingenious magnetic circuit design, the stator yoke is eliminated, achieving high torque density in the motor and helping to reduce the motor size, thereby realizing the lightweighting of wind turbine generator sets.

[0056] It should be noted that this invention focuses on the electromagnetic structure of the motor, and the mechanical and cooling structures of the motor in this invention will not be described in detail.

[0057] The above are merely preferred embodiments of the present invention and are not limited to the scope of implementation of the present invention. All equivalent changes and modifications made in accordance with the scope of the present invention should be within the technical scope of the present invention.

[0058] The embodiments of the present invention are merely illustrative examples of this patent and do not limit its scope of protection. Those skilled in the art can make partial changes to it, as long as they do not exceed the spirit and essence of this patent, they are all within the scope of protection of this patent.

Claims

1. A low-speed direct-drive generator with a single-tooth axial flux winding, a concentrated winding, and a multi-torque dual-rotor configuration, characterized in that... It includes a stator (2), a first rotor (1) and a second rotor (3), wherein the stator (2) is located between the first rotor (1) and the second rotor (3), the first rotor (1) and the second rotor (3) have the same structure, and the first rotor (1) and the second rotor (3) are symmetrical about the stator (2) and coaxially installed. There is an air gap between the stator (2) and the first rotor (1) and the second rotor (3). On the surface of the first rotor (11) facing the stator (2), a plurality of first rotor cores (4) are uniformly arranged circumferentially. A first rotor unit sector slot is formed between adjacent first rotor cores (4). On the surface of the second rotor (3) facing the stator (2), a plurality of second rotor cores (6) are uniformly arranged circumferentially. A second rotor unit sector slot is formed between adjacent second rotor cores (6). A first rotor permanent magnet (5) is provided in each first rotor unit sector slot, and a second rotor permanent magnet (7) is provided in each second rotor unit sector slot. The stator (2) has a circular ring structure. The stator (2) includes stator teeth (8), stator armature winding (9), lower stator Halbach permanent magnet array (10) and upper stator Halbach permanent magnet array (11). The stator teeth (8) are evenly arranged along the circumference, and parallel slots of stator units are formed between adjacent stator teeth (8). The stator armature winding (9) is wound on the stator teeth (8) using a single-tooth concentrated winding structure. The lower stator Halbach permanent magnet array (10) and the upper stator Halbach permanent magnet array (11) are evenly distributed at the slot openings on both sides of the parallel slots of the stator units with the axis of the stator (2) as the center, and are located on both sides of the stator armature winding (9). The lower stator Halbach permanent magnet array (10) and the upper stator Halbach permanent magnet array (11) both include a first stator permanent magnet (10-1), a second stator permanent magnet (10-2) and a third stator permanent magnet (10-3) distributed in sequence. The number of sector slots in the first rotor unit and the number of sector slots in the second rotor unit are both half the number of pole pairs of the stator armature winding (9). satisfy: ; Among them, after the stator armature winding (9) is supplied with three-phase symmetrical alternating current, it forms a number of magnetic pole pairs of . P sah The number of pole pairs of the permanent magnet on a rotor is P rf The number of stator teeth (8) is N s ; i and j The number of pole pairs in the stator permanent magnet is an integer; P sf The number of teeth on the rotor is N r ; k and l It is an integer.

2. The axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator according to claim 1, characterized in that, The magnetization direction of the second stator permanent magnet (10-2) is along the axial direction.

3. The axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator according to claim 1, characterized in that, The polarity of the second stator permanent magnet (10-2) is the same as that of the second rotor permanent magnet (7).

4. The axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator according to claim 1, characterized in that, The first stator permanent magnet (10-1) and the third stator permanent magnet (10-3) are both magnetized radially along the circumference and are facing each other.

5. The axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator according to claim 1, characterized in that, Both the first rotor permanent magnet (5) and the second rotor permanent magnet (7) are magnetized along the axial direction and have the same polarity. The first rotor permanent magnet (5) and the rotor teeth of the first rotor core (4) form an alternating pole structure, and the second rotor permanent magnet (7) and the rotor teeth of the second rotor core (6) form an alternating pole structure.

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