Speed-increasing type semi-direct-drive wind driven generator

Abstract

The utility model relates to a speed-increasing type semi-direct-driven wind driven generator, and belongs to the field of wind power. The speed-increasing type semi-direct-driven wind driven generator comprises a stator, an outer rotor and an inner rotor, the stator, the outer rotor and the inner rotor form a two-layer air gap radial structure; the outer rotor comprises outer rotor iron blocks and permanent magnets and adopts a spoke type structure; the stator and the inner rotor form a synchronous motor; the outer rotor, the stator teeth and the inner rotor form a magnetic gear box; an inner rotor permanent magnet adopts an NE Halbach array, the array is a pair of poles formed by three blocks, and the three blocks are respectively composed of permanent magnet blocks with magnetization angles of-135 degrees and-90 degrees, permanent magnet blocks with magnetization angles of-45 degrees and 45 degrees, and permanent magnet blocks with magnetization angles of 90 degrees and 135 degrees. The utility model integrates the functions of the gear box and the motor, has the advantages of small volume, high efficiency, low cost and the like, not only can efficiently generate power at normal wind speed, but also can assist in starting the rotation of the wind wheel, reduce the starting resistance moment and realize low-wind-speed power generation when the wind speed is lower than the cut-in wind speed.

Description

Technical Field

[0001] This utility model relates to a wind turbine generator, and more particularly to a speed-increasing semi-direct-drive wind turbine generator, belonging to the field of wind power generation technology. Background Technology

[0002] Semi-direct-drive wind turbines combine the advantages of permanent magnet direct-drive and doubly-fed wind turbines, and have become one of the mainstream models. Currently, semi-direct-drive wind turbines all use mechanical gearboxes for speed increase, that is, they adopt a generator + mechanical gearbox structure. However, mechanical gearboxes use mechanical gear meshing, which requires a complex oil lubrication system. This results in problems such as large size, high mechanical wear, and high failure rate in existing structures. Once a failure occurs, the maintenance cost is high, the downtime is long, and it leads to huge economic losses.

[0003] Magnetic gears, as a novel transmission method, offer advantages such as no mechanical contact, no wear, no maintenance, no noise, no lubrication required, and overload protection, leading to their increasing attention and application in recent years. Magnetic gearboxes feature physical isolation, require no lubrication, are small in size, lightweight, consume little energy, and transmit high torque, thus significantly reducing the operating and maintenance costs of large wind turbine units, especially semi-direct-drive and doubly-fed wind turbine units, while improving system performance and reliability.

[0004] Traditional permanent magnet motors typically use radial magnetization, which, while simple and easy to implement, has limitations in terms of torque ripple and cogging torque, affecting the motor's smoothness and efficiency. The Halbach array, through its unique magnetic field distribution design, can improve magnetic field strength and reduce torque ripple and cogging torque, thereby optimizing motor performance; however, its magnetic field modulation efficiency is limited due to the single arrangement of the magnetization array.

[0005] Therefore, there is an urgent need to develop a speed-increasing semi-direct drive wind turbine generator that integrates a speed-increasing magnetic gearbox and a generator, which is small in size, highly efficient, and low in cost.

[0006] This invention proposes a novel, high-efficiency permanent magnet Halbach magnetization array (hereinafter referred to as NE Halbach), and based on this array, constructs a speed-increasing semi-direct-drive wind turbine generator integrating a speed-increasing magnetic gearbox and a generator. The proposed NE Halbach magnetization array method breaks away from the traditional Halbach magnetization arrangement where magnets rotate sequentially at the same angle. By adjusting the angle of the magnetization array, goals such as low energy consumption, high efficiency, low torque pulsation, and low cogging torque can be achieved. Summary of the Invention

[0007] The main purpose of this utility model is to address the shortcomings and gaps in the existing technology by providing a speed-increasing semi-direct-drive wind turbine generator. By combining magnetic field modulation and a novel NE Halbach magnetizing array, it integrates the functions of a speed-increasing magnetic gearbox, generator, and motor into one unit. It has the advantages of small size, high efficiency, and low cost. It can not only efficiently convert wind energy into electrical energy under normal wind speed conditions, but also act as a motor to assist in starting the wind turbine rotation when the wind speed is lower than the cut-in wind speed, thereby reducing the starting resistance torque and realizing low-wind-speed power generation.

[0008] To achieve the above objectives, the speed-increasing semi-direct-drive wind turbine of this utility model includes: a stator, an outer rotor, an inner rotor, and a shaft; one end of the shaft is fixed to the outer rotor, and the other end is connected to the wind turbine main shaft; the stator is connected to the turbine-side converter.

[0009] The stator, outer rotor, and inner rotor form a two-layer air gap radial structure, wherein the stator is on the outer side, the outer rotor is in the middle, and the inner rotor is on the inner side.

[0010] The outer rotor includes an outer rotor iron block and an outer rotor permanent magnet, which adopt a spoke structure. The outer rotor permanent magnet and the outer rotor iron block are bonded together at intervals. The inner rotor includes an inner rotor iron core and an inner rotor permanent magnet. The inner rotor permanent magnet is bonded to the outside of the inner rotor iron core. The outer rotor iron block adopts an I-shaped structure to facilitate better fixation with the outer rotor permanent magnet.

[0011] The inner rotor permanent magnet adopts an NE Halbach array, which consists of three blocks forming a pair of poles. The first block consists of a permanent magnet block with a magnetization angle of -135° and a magnetization angle of -90°, the second block consists of a permanent magnet block with a magnetization angle of -45° and a magnetization angle of 45°, and the third block consists of a permanent magnet block with a magnetization angle of 90° and a magnetization angle of 135°.

[0012] The stator includes stator windings and a stator core. The stator teeth are straight teeth used for magnetic field modulation, similar to the magnetic adjustment ring of a magnetic gear. The number of stator teeth is equal to the sum of the number of pole pairs of the inner rotor and the number of pole pairs of the outer rotor.

[0013] The stator and the inner rotor constitute a synchronous motor; the outer rotor, stator teeth, and inner rotor constitute a magnetic gearbox, the speed ratio of which is the ratio of the number of pole pairs of the outer rotor to the number of pole pairs of the inner rotor.

[0014] The beneficial effects of this utility model are:

[0015] 1) The permanent magnet NE Halbach array proposed in this utility model can significantly improve the electromagnetic performance of the motor and enhance the sinusoidality of the air gap magnetic flux by optimizing the arrangement of permanent magnets, thereby improving the generator efficiency and reducing torque pulsation.

[0016] 2) This utility model of speed-increasing wind turbine integrates a speed-increasing magnetic gearbox and a generator into one unit. It has a compact structure and advantages such as small size, high efficiency, low cost, light weight, low energy consumption, and high reliability.

[0017] 3) Because the magnetic gearbox has no mechanical meshing and is a non-contact transmission, it achieves mechanical isolation. The mechanical vibration of the wind turbine will not be transmitted to the generator, which can effectively solve the inherent resonance and noise problems of mechanical wind turbine gearboxes. In addition, except for the bearings, there is no need for lubrication, which eliminates the need for a complex and cumbersome oil lubrication and cooling system, and can greatly reduce the operation and maintenance costs of wind turbines. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the topology and power generation system of the speed-up semi-direct drive wind turbine of this utility model.

[0019] Figure 2 This is a cross-sectional view and a schematic diagram of the three-dimensional topology of the stator and rotor of the speed-increasing semi-direct drive wind turbine of this utility model.

[0020] Figure 2 A cross-sectional view of the speed-increasing semi-direct drive wind turbine of this utility model.

[0021] Figure 2 b. Schematic diagram of the three-dimensional topology of the stator and rotor of the speed-up semi-direct drive wind turbine generator of this utility model.

[0022] Figure 3 This is a schematic diagram of the external rotor I-shaped iron core structure of this utility model.

[0023] Figure 4 This is a schematic diagram of the NE Halbach array of the inner rotor permanent magnet in the speed-up semi-direct drive wind turbine of this utility model.

[0024] Figure 5 This is a schematic diagram of energy transfer in electric motor mode for the speed-up semi-direct drive wind turbine of this utility model.

[0025] Figure 6 This is a schematic diagram of energy transfer in generator mode for the speed-up semi-direct drive wind turbine of this utility model.

[0026] Figure 7 This is a schematic diagram of a traditional 30°, 45°, and 60° Halbach array.

[0027] Figure 7a is a schematic diagram of a traditional 30° Halbach array.

[0028] Figure 7 b is a schematic diagram of a traditional 45° Halbach array.

[0029] Figure 7 c is a schematic diagram of a traditional 60° Halbach array.

[0030] Figure 8 The diagram shows a comparison of magnetic flux density and harmonics at the inner rotor core and stator core using a conventional Halbach array and the NE Halbach array of this invention.

[0031] Figure 8 Figure a shows a comparison of magnetic flux density and harmonics at the inner rotor core using a traditional Halbach array and the NE Halbach array of this invention.

[0032] Figure 8 b is a comparison diagram of magnetic flux density and harmonics at the stator core using a traditional Halbach array and the NE Halbach array of this invention.

[0033] Figure 9 This is a comparison chart of torque under different Halbach arrays.

[0034] Figure 10 This is a comparison chart of torque ripple under different Halbach arrays.

[0035] Among them, 1-stator; 2-outer rotor; 3-inner rotor; 4-shaft; 5-outer shell; 6-wind turbine main shaft; 7-wind turbine; 8-machine-side converter; 11-stator core; 12-stator winding; 21-outer rotor iron block; 22-outer rotor permanent magnet; 31-inner rotor core; 32-inner rotor permanent magnet. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the present invention is a speed-increasing semi-direct drive wind turbine generator, including: a stator 1, an outer rotor 2, an inner rotor 3, a shaft 4, a housing 5, etc.; one end of the shaft 4 is fixed to the outer rotor 2, and the other end is connected to the wind turbine main shaft 6; the stator winding 12 of the stator 1 is connected to the turbine-side converter 8 (MSC).

[0038] Stator 1, outer rotor 2, and inner rotor 3 form a two-layer air gap radial structure, with stator 1 on the outer side, outer rotor 2 in the middle, and inner rotor 3 on the inner side.

[0039] like Figure 2As shown, the outer rotor 2 includes an outer rotor iron block 21 and an outer rotor permanent magnet 22, adopting a spoke-type structure, with the outer rotor permanent magnet 22 and the outer rotor iron block 21 bonded together at intervals; the inner rotor 3 includes an inner rotor iron core 31 and an inner rotor permanent magnet 32, with the inner rotor permanent magnet 32 ​​bonded to the outside of the inner rotor iron core 31; as shown... Figure 3 As shown, the outer rotor iron block 21 adopts an I-shaped structure to facilitate better fixation with the outer rotor permanent magnet 22.

[0040] Furthermore, such as Figure 4 As shown, the inner rotor permanent magnet 31 adopts a new type of high-efficiency NE Halbach array. The NE Halbach array consists of three blocks forming a pair of poles. The first block consists of a permanent magnet block with a magnetization angle of -135° and a magnetization angle of -90°. The second block consists of a permanent magnet block with a magnetization angle of -45° and a magnetization angle of 45°. The third block consists of a permanent magnet block with a magnetization angle of 90° and a magnetization angle of 135°.

[0041] Stator 1 includes stator winding 12 and stator core 11; stator winding 12 is a three-phase AC winding; stator teeth are spur teeth used for magnetic field modulation, similar to the adjusting ring of a magnetic gear, hence stator teeth are also called modulation teeth; the number of stator teeth N s Equal to the number of external rotor pole pairs p out With the number of pole pairs p of the inner rotor in The sum, i.e., N s =p out +p in .

[0042] Stator 1 and inner rotor 3 constitute a synchronous motor, and the number of pole pairs of stator winding 12 is equal to the number of pole pairs of inner rotor.

[0043] The outer rotor 2, stator teeth, and inner rotor 3 constitute a magnetic gearbox, and its speed ratio G is equal to the number of pole pairs p of the outer rotor. out The number of pole pairs p of the inner rotor in The ratio, i.e.: G=p out / p in .

[0044] This utility model discloses a speed-increasing semi-direct-drive wind turbine generator, the working process of which is as follows:

[0045] 1. When the wind speed is lower than the cut-in wind speed, the speed-increasing semi-direct-drive wind turbine is operated in motor + reduction mode: the generator-side converter 8 is in inverter mode, and the stator winding 12 is energized. At this time, the stator 1 and the inner rotor 3 form a motor, and the inner rotor 3 rotates. The inner rotor 3 is reduced in speed by a magnetic gearbox consisting of the inner rotor 3, stator teeth, and outer rotor 2, which drives the outer rotor 2 to rotate, thereby driving the wind turbine main shaft 7 to rotate. At this time, the magnetic gearbox is a reduction gearbox with a reduction ratio of G. d =pin / p out .

[0046] Figure 5 This is the energy transfer diagram for this mode. When the stator winding 12 is energized, its power is output from its port, and the generated magnetic field couples with the magnetic fields of the inner and outer rotors. Part of the power is transferred to the outer rotor 2; part of the power is transferred to the inner rotor 3 and induces a magnetic torque. This magnetic torque is also transferred to the outer rotor 2 after coupling with the magnetic fields of the inner and outer rotors. The outer rotor 2 drives the wind turbine main shaft 6 to rotate through the rotating shaft 4, and the wind turbine main shaft 6 drives the wind turbine 7 to rotate. At the same time, the mechanical torque generated by the breeze also drives the wind turbine 7 to rotate. At this time, the power P output by the outer rotor 2 to the wind turbine 7 is... o The electromagnetic power P transmitted from stator winding 12 to the outer rotor wo The magnetic power P output by the inner rotor 3 to the outer rotor 2 io The sum of these is:

[0047] (1)

[0048] 2. When the wind speed is greater than the cut-in wind speed and the rotor speed reaches the grid-connected speed, the speed-increasing semi-direct-drive wind turbine operates in speed-increasing + generator mode: the turbine-side converter 8 is in rectification mode, controlling the operation of the speed-increasing semi-direct-drive wind turbine; at this time, the rotor main shaft 6 drives the outer rotor 2 to rotate, and the outer rotor 2 is speed-increasing through the magnetic gearbox formed by the outer rotor 2, stator teeth, and inner rotor 3, driving the inner rotor 3 to rotate. Since the stator 1 and the inner rotor 3 form a generator, the stator winding 12 outputs current, and the speed-increasing semi-direct-drive wind turbine starts generating electricity; at this time, the magnetic gearbox is a speed-increasing gearbox, and its speed-increasing ratio is G. i =p out / p in .

[0049] Once the wind turbine 7 rotates, it gains kinetic energy and reaches a certain speed. According to Newton's second law, the turbine speed can be further increased. Because the acceleration is small, the required wind force is relatively small; even a light breeze can maintain the turbine's rotation, thus achieving low-wind-speed power generation. The equation of motion at this point is:

[0050] (2)

[0051] In the formula, T W The wind turbine torque T provided to wind turbine 7 e J is the electromagnetic torque generated by the stator winding 12, J is the moment of inertia, and ω is the angular velocity of the wind turbine 7.

[0052] Figure 6The energy transfer diagram for this mode is shown. The mechanical power generated by the wind turbine 7 flows into the outer rotor 2, part of which induces electromagnetic torque in the stator winding 12; another part, through the coupling of the inner and outer rotor magnetic fields, generates magnetic torque in the inner rotor 3, which in turn induces electromagnetic torque in the stator winding 12, resulting in an output power P from the stator winding 12. w It is equal to the electromagnetic power P induced by the outer rotor on the stator winding 12. ow The electromagnetic power P induced in the stator winding 12 by the inner rotor 3 iw The sum of these is:

[0053] (3)

[0054] The following preferred embodiment will be used to further illustrate the present invention's speed-up semi-direct drive wind turbine.

[0055] Take a 5kW speed-up semi-direct drive wind turbine as an example.

[0056] Figure 7 Showing the traditional 30° ( Figure 7 a) 45° Figure 7 b) 60° Figure 7 c) The pole pair design of the Halbach array, wherein the number of permanent magnets per pole is 6, 4, and 3 respectively. Compared with the 30°, 45°, and 60° Halbach arrays, the magnetization method of the NEHalbach array of this invention removes the two horizontally magnetized permanent magnets in the 45° magnetization array, making the magnetic field lines denser and more direct.

[0057] Figure 8 For the inner rotor core 31 in the case of using 30°, 45°, 60° Halbach array and the NE Halbach array of this utility model ( Figure 8 a) and stator core at point 11 ( Figure 8 b) shows the magnetic flux density comparison diagram. As can be seen from the diagram, using the NE Halbach array of this invention, the magnetic flux density is lowest at the inner rotor core 31 (away from the air gap side), at 0.11T; while the magnetic flux density is highest at the stator core 11 (air gap side), at 0.21T. Therefore, it is evident that the NE Halbach array of this invention can enable wind turbines to achieve better performance.

[0058] Figure 9 The figure shows a comparison of torques at different initial angles for various Halbach arrays. It can be clearly seen from the figure that, under the same size, the wind turbine generator of the NE Halbach array of this invention has the highest torque, which is close to the rated torque.

[0059] Figure 10Torque ripple was compared across different Halbach arrays. Analysis shows that large torque ripple will affect the stable operation of the motor. According to... Figure 8 The torque ripple at 30°, 45°, 60° and NE Halbach arrays were 1.31%, 1.15%, 4.21% and 2.46%, respectively, all of which were small and not significantly different.

[0060] In summary, this utility model of a speed-increasing semi-direct-drive wind turbine has advantages such as small size, high efficiency, low cost, light weight, and high reliability. It can not only efficiently convert wind energy into electrical energy under normal wind speed conditions, but also be used as an electric motor when the wind speed is lower than the cut-in wind speed to assist in starting the wind turbine rotation, reduce the starting resistance torque, and achieve low wind speed power generation.

Claims

1. A speed-increasing semi-direct-drive wind turbine generator, characterized in that: It includes a stator, an outer rotor, an inner rotor, and a rotating shaft; one end of the rotating shaft is fixed to the outer rotor, and the other end is connected to the wind turbine main shaft; the stator is connected to the turbine-side converter; The stator, outer rotor, and inner rotor form a two-layer air gap radial structure, wherein the stator is on the outer side, the outer rotor is in the middle, and the inner rotor is on the inner side. The outer rotor includes an outer rotor iron block and an outer rotor permanent magnet, adopting a spoke structure, with the outer rotor permanent magnet and the outer rotor iron block being bonded at intervals; the inner rotor includes an inner rotor iron core and an inner rotor permanent magnet, with the inner rotor permanent magnet bonded to the outside of the inner rotor iron core; the outer rotor iron block adopts an I-shaped structure to facilitate better fixation with the outer rotor permanent magnet; The stator includes a stator winding and a stator core. The stator teeth are straight teeth used for magnetic field modulation, similar to the magnetic adjustment ring of a magnetic gear. The number of stator teeth is equal to the sum of the number of pole pairs of the inner rotor and the number of pole pairs of the outer rotor. The stator and the inner rotor constitute a synchronous motor; the outer rotor, stator teeth, and inner rotor constitute a magnetic gearbox, the speed ratio of which is the ratio of the number of pole pairs of the outer rotor to the number of pole pairs of the inner rotor.

2. The speed-increasing semi-direct-drive wind turbine generator as described in claim 1, characterized in that: The inner rotor permanent magnet adopts an NE Halbach array, which consists of three blocks forming a pair of poles. The first block consists of a permanent magnet with a magnetization angle of -135° and a magnetization angle of -90°, the second block consists of a permanent magnet with a magnetization angle of -45° and a magnetization angle of 45°, and the third block consists of a permanent magnet with a magnetization angle of 90° and a magnetization angle of 135°.

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