Axial flux permanent magnet doubly-fed wind generator for power splitting transmission system

Abstract

The application discloses an axial flux permanent magnet doubly-fed wind generator for a frequency division power transmission system, which comprises a stator and a rotor, the stator and the rotor are coaxially installed, and the stator and the rotor have an air gap therebetween; the rotor comprises a rotor iron core and a plurality of rotor permanent magnets, each rotor permanent magnet is installed on the surface of one side of the rotor iron core close to the air gap in sequence along the circumference; the stator comprises a stator iron core and a stator armature winding, the surface of one side of the stator iron core opposite to the rotor is provided with a plurality of stator teeth, and the stator armature winding comprises a 50 / 3 Hz winding and a 50 Hz winding; the 50 / 3 Hz winding and the 50 Hz winding are wound on the stator teeth respectively, the generator can respectively emit 50 / 3 Hz and 50 Hz electric energy, and has the characteristics of high economy, high operation reliability and superior performance.

Description

Technical Field

[0001] This invention belongs to the field of new energy and power engineering technology, and relates to an axial flux permanent magnet doubly fed wind turbine generator for frequency division transmission system. Background Technology

[0002] Wind turbines, as the conversion unit between wind energy and electrical energy, are one of the core components of frequency-division transmission systems. Currently, scholars have studied the types of generators suitable for frequency-division transmission systems, and the results show that traditional low-speed direct-drive permanent magnet generators can be used in these systems. However, when traditional direct-drive permanent magnet generators are connected to the grid, a full-power inverter is required for rectification and inversion to output stable 50 / 3 Hz AC power. For high-power offshore wind turbines, the required inverter capacity and cost are enormous. Furthermore, when traditional direct-drive permanent magnet wind turbines are used in frequency-division transmission systems, they can only generate 50 / 3 Hz power, while the power plant's power system requires 50 Hz power. To meet the needs of the plant's power system, additional frequency converters are usually required, further increasing the cost of the frequency-division transmission system. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an axial flux permanent magnet doubly fed wind turbine generator for frequency division transmission systems. This generator can generate 50 / 3 Hz and 50 Hz electrical energy respectively, and has the characteristics of high economy, high operational reliability and superior performance.

[0004] To achieve the above objectives, the present invention discloses an axial flux permanent magnet doubly fed wind turbine generator for a frequency division transmission system, comprising a stator and a rotor, wherein the stator and rotor are coaxially mounted and an air gap exists between the stator and rotor;

[0005] The rotor includes a rotor core and several rotor permanent magnets, with each rotor permanent magnet being sequentially mounted circumferentially on the surface of the rotor core near the air gap.

[0006] The stator includes a stator core and a stator armature winding. The surface of the stator core facing the rotor has a number of stator teeth. The stator armature winding includes a 50 / 3 Hz winding and a 50 Hz winding, which are wound on the stator teeth respectively.

[0007] Stator slots are formed between adjacent stator teeth, and the stator armature windings are located within the stator slots.

[0008] The 50 / 3 Hz winding is wound on the stator teeth in a three-phase symmetrical winding structure. When in operation, the 50 / 3 Hz winding generates a fundamental magnetic field with p pole pairs.

[0009] The 50 Hz winding is wound in the remaining space of the stator teeth according to a three-phase symmetrical winding structure. When working, the 50 Hz winding generates a fundamental magnetic field with 3p pole pairs, where p is a positive integer.

[0010] The number of pole pairs of the rotor permanent magnet is the same as the number of pole pairs of the 50 / 3 Hz winding.

[0011] The axial thickness of each rotor permanent magnet gradually changes along the rotor circumference.

[0012] Each rotor permanent magnet is uniformly distributed circumferentially, and the axial thickness of each rotor permanent magnet gradually changes along the rotor circumference. The axial component of the air gap magnetomotive force generated by the rotor permanent magnet includes a fundamental wave with p pole pairs and a harmonic wave with 3p pole pairs. The axial thickness h of the rotor permanent magnet is:

[0013]

[0014] Where h1 and h2 are thickness adjustment factors, and α is the circumferential angle, with a value ranging from 0° to 360°. By changing the values ​​of h1 and h2, the magnitudes of the fundamental wave and the 3p pole harmonic in the air gap magnetomotive force are adjusted.

[0015] The 50 / 3 Hz winding interacts with the magnetic field of the p-pole in the air gap to generate alternating current with a frequency of 50 / 3 Hz.

[0016] The 50 Hz winding interacts with the magnetic fields of the p-pair and 3p-pair in the air gap to generate alternating current with a frequency of 50 Hz.

[0017] The present invention has the following beneficial effects:

[0018] In the specific operation of the axial flux permanent magnet doubly-fed wind turbine generator used in the frequency division transmission system of this invention, the stator and rotor are installed coaxially with an air gap between them. The stator armature winding includes a 50 / 3 Hz winding and a 50 Hz winding, which are respectively wound on the stator teeth. During operation, the 50 / 3 Hz winding and the 50 Hz winding generate 50 / 3 Hz electrical energy and 50 Hz electrical energy, respectively. The 50 / 3 Hz electrical energy can be directly transmitted to the frequency division transmission grid, thereby eliminating the need for an intermediate frequency converter and improving the economy and reliability of the frequency division transmission system. The 50 Hz electrical energy can be connected to the frequency division transmission grid through a frequency converter and simultaneously directly connected to the power plant's auxiliary power system, thereby eliminating the need for a frequency converter between the wind turbine generator and the power plant and further improving the economy and operational reliability of the entire system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the rotor 2 in this invention;

[0021] Figure 3 This is an exploded view of the stator 1 structure in this invention;

[0022] Figure 4 This is a diagram showing the harmonic content of the axial component of the unloaded air gap magnetic flux density of the present invention.

[0023] Figure 5 This is the back EMF diagram of the 50 / 3 Hz winding 6-1 in this invention;

[0024] Figure 6 This is the back electromotive force diagram of the 50 Hz winding 6-2 in this invention.

[0025] In this diagram, 1 is the stator, 2 is the rotor, 3 is the rotor core, 4 is the rotor permanent magnet, 5 is the stator core, 6 is the stator armature winding, 6-1 is the 50 / 3 Hz winding, and 6-2 is the 50 Hz winding. 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 Figure 1 The axial flux permanent magnet doubly fed wind turbine generator for frequency division transmission system of the present invention includes a stator 1 and a rotor 2. The stator 1 and the rotor 2 are coaxially mounted, with the stator 1 facing the rotor 2, and there is an air gap between the stator 1 and the rotor 2.

[0029] refer to Figure 1 and Figure 2The rotor 2 includes a rotor permanent magnet 4 and a rotor core 3. The rotor core 3 is annular, and the rotor permanent magnet 4 is mounted on the surface of the rotor core 3 near the air gap.

[0030] See Figure 1 and Figure 3 The stator 1 includes a stator core 5 and a stator armature winding 6. The stator core 5 is directly opposite the rotor 2. Several stator teeth are provided on the surface of the stator core 5 facing the rotor 2. Stator slots are formed between adjacent stator teeth. The stator armature winding 6 is wound on the stator teeth and is located in the stator slot.

[0031] The stator armature winding 6 includes a 50 / 3 Hz winding 6-1 and a 50 Hz winding 6-2. The 50 / 3 Hz winding 6-1 is wound around the stator teeth in a three-phase symmetrical winding structure. During operation, the 50 / 3 Hz winding 6-1 generates a fundamental magnetic field with p pole pairs. The 50 Hz winding 6-2 is wound around the remaining space of the stator teeth in a three-phase symmetrical winding structure. During operation, the 50 Hz winding 6-2 generates a fundamental magnetic field with 3p pole pairs, where p is a positive integer.

[0032] See Figure 2 The number of pole pairs of the rotor permanent magnet 4 is the same as the number of pole pairs of the 50 / 3 Hz winding 6-1, both being p pole pairs.

[0033] Each rotor permanent magnet 4 is uniformly distributed circumferentially, and the axial thickness of each rotor permanent magnet 4 gradually changes along the circumference of the rotor 2. The axial component of the air gap magnetomotive force generated by the rotor permanent magnet 4 includes a fundamental wave with p pole pairs and a harmonic wave with 3p pole pairs. The axial thickness h of the rotor permanent magnet 4 is:

[0034]

[0035] Where h1 and h2 are thickness adjustment factors, and α is the circumferential angle, with a value ranging from 0° to 360°. By changing the values ​​of h1 and h2, the magnitudes of the fundamental wave and the 3p pole harmonic in the air gap magnetomotive force are adjusted.

[0036] When the present invention is in operation, the 50 / 3 Hz winding 6-1 interacts with the magnetic field of the p-p pair in the air gap to generate alternating current with a frequency of 50 / 3 Hz; the 50 Hz winding 6-2 interacts with the magnetic fields of the p-p and 3p pairs in the air gap to generate alternating current with a frequency of 50 Hz.

[0037] Example 1

[0038] refer to Figure 1 In this embodiment, a generator with two pole pairs as the fundamental wave of the axial component of the air gap magnetic field is used as an example, i.e., p = 2.

[0039] In this embodiment, by changing the values ​​of h1 and h2, the magnitudes of the two pairs of fundamental waves and the six pairs of harmonic waves in the air gap magnetomotive force can be adjusted. In this embodiment, h1 is twice the size of h2.

[0040] In this embodiment, the rated speed of rotor 2 is 500 rpm. At the rated speed, the 50 / 3 Hz winding 6-1 interacts with the magnetic field of the two pairs of poles in the air gap to generate alternating current with a frequency of 50 / 3 Hz; the 50 Hz winding 6-2 interacts with the magnetic fields of the two pairs of poles and the six pairs of poles in the air gap to generate alternating current with a frequency of 50 Hz.

[0041] Figure 5 and Figure 6 The back potential waveform diagram of the present invention is shown below. Figure 5 It can be seen that the output frequency of the 50 / 3 Hz winding 6-1 in this invention is a voltage with a frequency of 50 / 3 Hz, which is determined by... Figure 6 It can be seen that the output frequency of the 50 Hz winding 6-2 is a voltage of 50 Hz, so that the two sets of windings can output electrical energy of different frequencies respectively.

[0042] In summary, this invention can generate 50 / 3 Hz and 50 Hz electrical energy respectively during operation. The 50 / 3 Hz energy can be directly transmitted to the frequency-division power grid, eliminating the need for an intermediate frequency converter and improving the economy and reliability of the frequency-division power transmission system. The 50 Hz energy can be connected to the frequency-division power grid via a frequency converter and simultaneously connected directly to the power plant's auxiliary power system, eliminating the need for a frequency converter between the wind turbine and the power plant, further improving the economy and operational reliability of the entire system. Furthermore, this invention only requires control of the 50 Hz winding 6-2 to adjust and control the wind turbine's operating status, thus simplifying the control system and further improving the overall system's economy and reliability.

[0043] This invention patent takes a single-stator single-rotor axial flux motor model as an example. Other multi-stator multi-rotor motors that conform to the principles described in this patent are also within the scope of protection of this patent.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An axial flux permanent magnet doubly-fed wind turbine generator for a frequency division transmission system, characterized in that, It includes a stator (1) and a rotor (2), the stator (1) and the rotor (2) are coaxially mounted, and there is an air gap between the stator (1) and the rotor (2); The rotor (2) includes a rotor core (3) and several rotor permanent magnets (4), and each rotor permanent magnet (4) is installed in sequence along the circumferential direction on the surface of the rotor core (3) near the air gap; The stator (1) includes a stator core (5) and a stator armature winding (6). The surface of the stator core (5) facing the rotor (2) is provided with a plurality of stator teeth. The stator armature winding (6) includes a 50 / 3 Hz winding (6-1) and a 50 Hz winding (6-2). The 50 / 3 Hz winding (6-1) and the 50 Hz winding (6-2) are respectively wound on the stator teeth. The 50 / 3 Hz winding (6-1) is wound around the stator teeth in a three-phase symmetrical winding structure. During operation, the 50 / 3 Hz winding (6-1) generates a number of magnetic pole pairs. p The fundamental magnetic field of the opposite pole, wherein, p It is a positive integer; The 50 Hz winding (6-2) is wound in the remaining space of the stator teeth according to a three-phase symmetrical winding structure. During operation, the 50 Hz winding (6-2) generates 3 magnetic pole pairs. p The fundamental magnetic field of the opposite pole.

2. The axial flux permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 1, characterized in that, Stator slots are formed between adjacent stator teeth, and the stator armature winding (6) is located in the stator slots.

3. The axial flux permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 1, characterized in that, The number of pole pairs of the rotor permanent magnet (4) is the same as the number of pole pairs of the 50 / 3 Hz winding (6-1).

4. The axial flux permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 3, characterized in that, 50 / 3 Hz winding (6-1) and air gap p The magnetic fields of opposite poles interact to generate alternating current with a frequency of 50 / 3 Hz.

5. The axial flux permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 4, characterized in that, 50 Hz winding (6-2) and 3 in the air gap p The magnetic fields of opposite poles interact to generate alternating current with a frequency of 50 Hz.

6. The axial flux permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 1, characterized in that, The axial thickness of each rotor permanent magnet (4) gradually changes along the circumference of the rotor (2).

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