Semi-direct-drive large wind turbine based on permanent magnet block and optimization method

Abstract

The present invention provides a semi-direct drive large wind turbine based on segmented permanent magnets and an optimization method, belonging to the technical field of semi-direct drive large permanent magnet synchronous wind turbines, including: a rotor, the rotor includes a plurality of permanent magnet units distributed circumferentially, and each permanent magnet unit includes a plurality of permanent magnet blocks; grooves are provided on both the inner layer and the outer layer of the permanent magnet blocks distributed circumferentially, and each groove is evenly distributed on the surface of the permanent magnet block in the radial direction, and the grooves provided on the inner layer and the outer layer are arranged alternately.

Description

Technical Field

[0001] The invention belongs to the technical field of semi-direct drive large permanent magnet synchronous wind turbines, and particularly relates to a semi-direct drive large wind turbine based on permanent magnet segmentation and an optimization method. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention, and do not necessarily constitute prior art.

[0003] As a core component of a wind power system, the performance of a large permanent magnet synchronous wind turbine has an important impact on the operating efficiency and reliability of a wind turbine unit. In the prior art, due to the advantages of both direct drive and gear drive systems, the semi-direct drive structure realizes efficient and reliable energy transfer by reducing the transmission link, and is widely used in high-power wind turbine units. However, with the continuous increase of the generator power level and size, the loss problem during its operation becomes more prominent, becoming an important bottleneck restricting the improvement of the generator efficiency.

[0004] Permanent magnets are key components of permanent magnet synchronous wind turbines, and their design plays a decisive role in the electromagnetic performance and operating efficiency of the generator. The traditional integral permanent magnet design is prone to generating relatively large permanent magnet eddy current losses, resulting in serious heating problems and increasing the risk of permanent magnet demagnetization. By dividing the permanent magnet into several small pieces, the segmented permanent magnet can effectively reduce the permanent magnet eddy current loss. However, since the permanent magnet needs to be insulated and re-fastened, this will increase the manufacturing cost and reduce the mechanical robustness of the permanent magnet.

[0005] For example, in CN118783672A - Axial magnetic field permanent magnet motor with segmented permanent magnets and its assembly method disclosed in the prior art, each permanent magnet structure includes several permanent magnet blocks, and each permanent magnet block is in contact with a magnetic conduction adapter plate. Through the above scheme, the magnetization difficulty and assembly difficulty of the motor with segmented permanent magnets are reduced. However, the existing problems are still:

[0006] Due to incomplete segmentation, the losses are concentrated in some regions of the permanent magnet, resulting in too high temperature of the permanent magnet under some conditions, leading to local demagnetization, thereby changing the air-gap magnetic density and reducing the motor efficiency. Summary of the Invention

[0007] To overcome the deficiencies of the above prior art, the present invention provides a semi-direct drive large wind turbine based on permanent magnet segmentation. Compared with the traditional integral permanent magnet, the permanent magnet eddy current loss of the generator is improved, and the generator efficiency is further increased.

[0008] To achieve the above object, one or more embodiments of the present invention provide the following technical solutions:

[0009] In a first aspect, a semi-direct drive large-scale wind turbine based on segmented permanent magnets is disclosed, including: a rotor, the rotor includes a plurality of permanent magnet units distributed circumferentially, and each permanent magnet unit includes a plurality of permanent magnet blocks;

[0010] Slots are provided on both the inner layer and the outer layer of the permanent magnet blocks distributed circumferentially. In the radial direction, each slot is evenly distributed on the surface of the permanent magnet block, and the slots provided on the inner layer and the outer layer are arranged alternately.

[0011] As a further technical solution, the wind turbine further includes a rotating shaft. A rotor and a stator are coaxially arranged with the rotating shaft, and there is an axial air gap between the rotor and the adjacent stator;

[0012] The stator is formed by stacking silicon steel sheets, and evenly distributed slots are punched on it. Three-phase symmetrical windings are placed in the slots, which are stator windings;

[0013] The slot type of the stator adopts an open slot, and a stator slot wedge is placed at the slot opening.

[0014] As a further technical solution, the stator winding is a double-layer winding, and the structure of the rotor adopts an embedded type, and the permanent magnet unit is embedded in the rotor core.

[0015] As a further technical solution, the permanent magnet blocks are parallel to each other and perpendicular to the radial direction.

[0016] As a further technical solution, the selection of the number of slots and poles of the stator is based on the greatest common divisor and the least common multiple of the number of slots and poles.

[0017] As a further technical solution, the embedded rotor, permanent magnets and stator core together constitute a magnetic circuit structure.

[0018] As a further technical solution, the three-phase double-layer integral slot overlapping winding is connected in a star connection mode, and the current flows out from the heads of the three-phase double-layer integral slot overlapping winding respectively, and the ends of the three-phase double-layer integral slot overlapping winding are connected together.

[0019] In a second aspect, an assembly method of a semi-direct drive large-scale wind turbine based on segmented permanent magnets is disclosed, including:

[0020] Slots are provided on both the inner layer and the outer layer of the permanent magnet blocks distributed circumferentially. In the radial direction, each slot is evenly distributed on the surface of the permanent magnet block, and the slots provided on the inner layer and the outer layer are arranged alternately.

[0021] The above one or more technical solutions have the following beneficial effects:

[0022] In the technical solution of the present invention, the stator part of the generator is made of stacked silicon steel sheets to reduce the stator iron loss. The stator is punched with evenly distributed slots, and three-phase symmetrical windings are placed in the slots. The stator slot type is an open slot, and a stator slot wedge is placed at the end of the slot. The stator winding is a double-layer overlapping winding, and the rotor structure is an embedded type. The surface of the permanent magnet is incompletely segmented, and the segmentation form is a bilateral alternating segmentation. Compared with the traditional integral permanent magnet, the eddy current loss of the permanent magnet of the generator is significantly improved, and the efficiency of the generator is further increased. The loss of this application reduces the area where the loss is concentrated due to the optimization of the structure.

[0023] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0025] Figure 1 It is a partial three-dimensional structure diagram of a semi-direct drive large permanent magnet synchronous wind turbine generator with a bilateral alternating type incompletely segmented permanent magnet in Embodiment 1 of the present invention;

[0026] Figure 2 It is a structure diagram of a bilateral alternating type incompletely segmented permanent magnet in Embodiment 1 of the present invention;

[0027] Figure 3 It is a diagram of the flow direction of eddy current on the permanent magnet; in the attached Figure 3 Figure (a) is a schematic diagram of the simulation segmentation method, and in the attached Figure 3 Figure (b) is a schematic diagram of the theoretical eddy current flow direction;

[0028] Figure 4 It is a distribution cloud diagram of eddy current density on the front surface of the permanent magnet;

[0029] Figure 5 It is a distribution cloud diagram of eddy current density on the back surface of the permanent magnet;

[0030] Figure 6 It is a flowchart of the motor assembly process;

[0031] Figure 7 It is a flowchart of the overall optimization method for this embodiment;

[0032] Figure 8 It is a schematic diagram of the particle swarm optimization algorithm for this embodiment;

[0033] Description of the reference numerals: 1, stator; 2, winding coil; 3, permanent magnet unit; 4, rotor; 5, housing; 6, rotating shaft. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0036] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0037] Embodiment 1

[0038] As Figure 1 shown, this embodiment discloses a semi-direct-drive large wind turbine based on permanent magnet block division, including: a stator 1, a winding coil 2, a permanent magnet unit 3, a rotor 4, and a rotating shaft 6. Among them, the rotor 4 and the stator 1 are coaxially arranged with the rotating shaft. The winding coil is nested in the stator teeth. The housing 5 is connected to the outside of the stator, wraps other components of the motor, is the outermost structure of the motor, and there are heat dissipation ribs on the outside of the housing to enhance the heat dissipation capacity of the motor.

[0039] In this embodiment, the concept of the semi-direct-drive generator is a solution that combines the problems encountered in the development of direct-drive generators and doubly-fed motors. It not only reduces the transmission ratio of the gearbox on the basis of the doubly-fed model but also improves the rotational speed and structural compactness on the basis of the direct-drive model, improving the reliability and service life of the gearbox. On the one hand, it reduces the volume and manufacturing cost of the generator, thereby reducing the overall weight of the nacelle and the pressure on the tower. On the other hand, the requirements for the speed increasing mechanism are greatly reduced, making the gearbox with the highest failure rate more reliable and stable.

[0040] There is an axial air gap between the rotor 4 and the adjacent stator 1. The rotor includes a number of permanent magnet units distributed circumferentially. Each permanent magnet unit includes three permanent magnet blocks. The permanent magnet blocks are parallel to each other and perpendicular to the radial direction of the plane where the rotor is located. The rotor adopts an internal type, that is, the permanent magnet unit is built into the rotor.

[0041] The internal rotor, the permanent magnet unit, and the stator together form a magnetic circuit structure. The magnetic induction lines are emitted from the permanent magnet unit, pass through the rotor to reach the air gap between the rotor and the stator, pass through the air gap and further reach the stator, generate an electromotive force by cutting the copper wire in the winding in the stator, and finally return to the permanent magnet unit built into the rotor through the air gap.

[0042] The permanent magnet unit adopts bilateral alternating incomplete segmentation on one side, that is, rectangular slots are made close to the edge on one surface of the permanent magnet. Radially, each slot is evenly distributed on the surface of the permanent magnet, and the slots are alternately made on both sides of the surface. Finally, the permanent magnet block is incompletely segmented, and the permanent magnet blocks are arranged according to units.

[0043] The three-phase double-layer integral-slot lap winding is in a star connection mode. Currents flow out from the heads of the three-phase double-layer integral-slot lap winding respectively, and the ends of the three-phase double-layer integral-slot lap winding are connected together.

[0044] The working principle of the above motor:

[0045] As the rotor rotates, the permanent magnet unit emits magnetic induction lines, which pass through the rotor to reach the air gap between the rotor and the stator, pass through the air gap and further reach the stator, cut the copper wires in the winding in the stator to generate back electromotive force, and then output to the power storage device. Finally, the magnetic induction lines return to the permanent magnet unit built in the rotor through the air gap.

[0046] The method for dividing permanent magnet blocks by bilateral alternating incomplete segmentation, that is, rectangular slots are made close to the edge on one surface of the permanent magnet unit. Radially, each slot is evenly distributed on the surface of the permanent magnet unit, and the slots are alternately made on both sides of the surface. The above means in this embodiment is different from the conventional complete block division method. Incomplete block division has high requirements for the accuracy and strength of the cutting equipment. This incomplete block division makes the mechanical stability of the permanent magnet higher, has a significant effect on weakening the eddy current loss of the permanent magnet, and reduces the occurrence of motor accidents.

[0047] The stator part of the generator is made of laminated silicon steel sheets to reduce the stator iron loss. Uniformly distributed slots are punched on it, and three-phase symmetrical windings are placed in the slots; the stator slot type is an open slot, and stator slot wedges are placed at the ends of the slots. The stator winding is a double-layer lap winding, and the rotor structure is an embedded type. The surface of the permanent magnet is incompletely segmented, and the segmentation form adopts bilateral alternating segmentation. Compared with the traditional integral permanent magnet, the eddy current loss of the permanent magnet of the generator is significantly improved, and the efficiency of the generator is further increased.

[0048] A large permanent magnet synchronous wind power generator using the method for dividing permanent magnet blocks by bilateral alternating incomplete segmentation. The bilateral alternating incomplete segmentation of the permanent magnet blocks used has lower permanent magnet eddy current loss for the traditional non-segmented permanent magnet; and has the characteristic of maintaining the mechanical stability of the permanent magnet for the completely segmented permanent magnet.

[0049] A scheme for dividing permanent magnet blocks by bilateral alternating incomplete segmentation provided in this embodiment can effectively reduce the eddy current loss of the permanent magnet and improve the efficiency of the generator.

[0050] A large permanent magnet synchronous wind turbine using a bilateral alternating incomplete segmentation permanent magnet block method provided in this embodiment adopts a three-phase integral slot double-layer winding structure, minimizing the winding end part, reducing the end copper loss, reducing the stator winding heating, and to a certain extent reducing the overall volume of the motor and improving the integration degree.

[0051] Specifically, as Figure 2 shown, for the bilateral alternating incomplete segmentation permanent magnet block, rectangular slots are adopted close to the edge on one surface of the permanent magnet. In the radial direction, each slot is evenly distributed on the surface of the permanent magnet, and the slots are alternately made on both sides of the surface.

[0052] As Figure 3 shown, the bilateral alternating incomplete segmentation permanent magnet block can make the eddy current of the permanent magnet change the direction from the cutting place, extending the path of the eddy current loss. After the direction change, the current density will be greatly reduced, so as to weaken the eddy current loss of the permanent magnet and improve the motor efficiency.

[0053] As Figure 4 and Figure 5 shown, where Ohmic-Loss corresponds to the Chinese of: permanent magnet eddy current loss, and W / m^3 is the permanent magnet eddy current loss density, representing how much loss per cubic meter; it can be seen from the cloud map of the permanent magnet eddy current loss in the motor simulation of the bilateral alternating incomplete segmentation permanent magnet block that the permanent magnet eddy current loss is mainly at the four peripheral edges of the permanent magnet. Since the segmentation extends the path of the eddy current loss, to a certain extent, the permanent magnet eddy current loss is weakened. At the incomplete segmentation place, due to the dense number of edges, the permanent magnet eddy current loss is relatively large here.

[0054] The stator part of this generator is made of laminated silicon steel sheets to reduce the stator iron loss. There are evenly distributed slots on it, and three-phase symmetrical windings are placed in the slots; the stator slot type adopts an open slot, and a stator slot wedge is placed at the slot opening. The stator winding is a double-layer winding, and the rotor structure adopts an interior type. The surface of the permanent magnet is incompletely segmented, and the segmentation form adopts bilateral alternating segmentation, that is, rectangular slots are adopted close to the edge on one surface of the permanent magnet. In the radial direction, each slot is evenly distributed on the surface of the permanent magnet, and the slots are alternately made on both sides of the surface. Compared with the traditional integral permanent magnet, the permanent magnet eddy current loss of the generator is improved, and the generator efficiency is further improved.

[0055] Embodiment 2

[0056] The purpose of this embodiment is to provide an assembly method for a semi-direct drive large wind turbine based on permanent magnet block. Different from other permanent magnet assembly methods, this method uses a fixed mold to fix the permanent magnet, enabling the permanent magnet to complete steps such as magnetization and incomplete segmentation.

[0057] Specifically, it includes the following steps: Refer toFigure 6 , the assembly method mainly includes:

[0058] S1: Install a number of permanent magnet units on the workbench.

[0059] Exemplarily, first, install all the permanent magnet blocks used to form the same permanent magnet unit on the workbench. When installing, the permanent magnet blocks can be installed on the workbench by means of external mold nesting.

[0060] S2: Magnetize the magnetic pole unit.

[0061] Exemplarily, place the assembled permanent magnet unit on the magnetizer to magnetize it.

[0062] Furthermore, in this step, place the permanent magnet unit in a strong magnetic field environment. Subsequently, by adjusting the intensity and direction of the magnetic field, the magnetic domain structure inside the magnetic material is forced to reorient. According to the size, shape of the magnetic material and the required magnetic performance indicators, accurately select the corresponding magnetic field intensity and magnetization time. During the magnetization process, the intensity and direction of the magnetic field must be strictly controlled to avoid damage to the magnetic properties of the magnetic material.

[0063] S3: Incompletely divide the magnetized permanent magnet blocks.

[0064] Exemplarily, place the magnetized permanent magnet blocks in the cutting equipment, and use a tool to physically cut the whole permanent magnet according to the model established for double-sided incomplete division as shown in Figure 3 the model shown.

[0065] S4: Install the magnetic pole unit to the rotor core to form a rotor.

[0066] Exemplarily, the magnetic pole unit can be fixedly installed on the rotor through the nested mold in the magnetized magnetic pole unit and the built-in rotor.

[0067] Embodiment III

[0068] The purpose of this embodiment is to provide an optimization method for a semi-direct drive large wind turbine based on permanent magnet segmentation. Generally, the permanent magnets are segmented in an average way. This method has mechanical deviations in processing. In reality, the eddy current loss density of the permanent magnets in some areas is higher than that in other parts, resulting in too high temperature in some areas, causing demagnetization in some areas and resulting in the non-uniformity of the permanent magnet magnetic field. Different from the average segmentation permanent magnet block optimization method, this method uses the particle swarm optimization algorithm. This optimization algorithm can obtain the optimal segmentation method through continuous iterative calculation. Under this segmentation method, it can ensure that the eddy current loss of the permanent magnets reaches the optimal distribution during segmentation, reducing the risk of demagnetization in some areas due to too high temperature of the permanent magnets. In the permanent magnet block design of the particle swarm optimization algorithm, referring to Figure 8 , the physical problem is transformed into a mathematical optimization model, and the design variables, objective function and constraint conditions are clarified, and the optimal solution is obtained after multiple iterations.

[0069] Specifically, it includes the following steps: Referring to Figure 7 , this particle swarm optimization algorithm mainly includes:

[0070] S1: Take the length, width and thickness of each magnetic block as geometric parameters, and the number of segments N as a discrete variable; regard each sub-block as a particle.

[0071] S2: Establish a magnetic field simulation model:

[0072] (1) Construct a three-dimensional permanent magnet motor model;

[0073] (2) Add excitation, boundary conditions and mesh generation;

[0074] (3) Set the step size and the final time for calculation.

[0075] S3: Configure the particle swarm optimization algorithm:

[0076] Add geometric constraints to ensure that the particles are always within the domain and do not exceed the boundary:

[0077] Add physical constraints to determine the size of the permanent magnets and link them with the engineering reality:

[0078] Particle coding and initialization:

[0079] Normalize the size, position and magnetization direction of each sub-block to the interval [0, 1].

[0080] S4: Iterative optimization:

[0081] Use the particle swarm optimization algorithm to update the speed of each logical instance in each particle in the current particle swarm.

[0082] In this embodiment, specifically, S1: The length, width, thickness, etc. of each magnetic block are used as geometric parameters; the number of divided blocks is variable, and the number N is used as a discrete variable. Each sub-block is regarded as a particle, and the size of each sub-block is: length 、width w i 、height h i ; The position coordinates of the sub-block: x i , y i , z i , with the center of the cuboid as the origin. The magnetization angle of each sub-block is: polar angle θ i 、azimuth angle .

[0083] The cuboid is divided into N sub-blocks, and the parameters of each sub-block are: x n = , w 1, h 1, x 1, y 1, z 1, θ 1, … ，w n ， h n ，x n ，y n ，z n , θ n ， .

[0084] In this embodiment, specifically, S2: Establish a magnetic field simulation model:

[0085] (1) Construct a three-dimensional permanent magnet motor model in Maxwell;

[0086] (2) Add excitation, boundary conditions, and mesh generation;

[0087] (3) Set the step size and final time for calculation.

[0088] In this embodiment, specifically, S3: Configure the particle swarm optimization algorithm:

[0089] It is necessary to quantify the magnetic field uniformity and energy conversion efficiency, and combine them into a single objective function through weighted combination:

[0090] ;

[0091] wherein, α、β is the weight coefficient, Uniformity ( x ) is the magnetic field uniformity function, Efficiency ( x ) is the energy conversion efficiency function, f ( x ) is the weighted objective function.

[0092] It should be noted that the weight coefficient α、β is different for each iteration, and the optimal coefficient is found through multiple iterations, α、β and its value range is [0, 1].

[0093] The magnetic field uniformity ( Uniformity ) is quantified using the magnetic field standard deviation or the maximum deviation. For example, M sampling points are set in the target area, and the variance of the magnetic induction intensity B k is calculated:

[0094] ;

[0095] wherein, Uniformity ( x ) is the magnetic field uniformity function; is the average magnetic induction intensity, B k is the air-gap magnetic flux density, M = 1, 2, 3 ….

[0096] The energy conversion efficiency ( Efficiency ) is defined by the ratio of the actual output power to the theoretical maximum power:

[0097] ;

[0098] wherein, Efficiency ( x ) is the energy conversion efficiency function; B is the air-gap magnetic flux density; B max is the maximum air-gap magnetic flux density; H is the magnetic field strength; H max is the maximum magnetic field strength, V is the volume.

[0099] Geometric constraints are added to ensure that the particles are always within the domain and do not exceed the boundaries:

[0100] The sub-blocks cannot overlap: for any two sub-blocks i ,j , satisfying . The total volume is constant: .

[0101] Among the above parameters, x i is the i th sub-block; x j is the j th sub-block; is the i length of the th sub-block; j is the N= length of the w i is the i width of the h i is the i height of the V total total volume of the permanent magnet.

[0102] Then add physical constraints to determine the size of the permanent magnet and link it to the engineering practice: The minimum size of the magnetic block: . is the i length of the w i is the i width of the h i is the i height of the is the i minimum length of the w min is the i minimum width of the h min is the i minimum height of the

[0103] Then encode and initialize the particles: Normalize the size, position, and magnetization direction of each sub-block to the interval [0, 1]. x n = , w 1, h 1, x 1, y 1, z 1, θ 1, … ，w n ，hn ，x n ，y n ，z n , θ n ， 。

[0104] The above actual size is , and the actual position is ; Randomly generate particle positions to ensure that the sub-blocks do not overlap and the total volume is constant. Set the initial velocity to v i = 0 or randomly generate within [-0.1, 0.1]. is the length of the i -th sub-block; L max is the maximum length of the sub-block; L min is the minimum length of the sub-block; is the normalized length after normalization, and the formula is ; x i is the position of the i -th sub-block; L max is the maximum length of the permanent magnet; L min is the minimum length of the permanent magnet; is the normalized position after normalization, and the formula is ; x max is the maximum position; x min is the minimum position.

[0105] In this embodiment, specifically, S4: Iterative optimization:

[0106] Use the particle swarm optimization algorithm to update the velocity of each logical instance in each particle in the current particle swarm. The velocity update formula is:

[0107] ;

[0108] Among them ，t is the number of iterations; i = 1, 2,... is the particle number, j is the particle dimension; w is the inertia weight, which controls the global and local balance of the search step; c 1, c 2 are learning factors, c 1 controls the influence of the individual optimum,c 2 Control the influence of global optimality; v ij For the particle i History j The speed of the generation time; x ij For the particle i History j The position of the generation time; p best，ij For the particle i The coordinates of the historical best position at the j generation time; g best，j Is the global best position; r 1. r 2 is a random number, which increases the randomness of the algorithm and avoids falling into local optimality.

[0109] After updating the speed and position of each particle in the particle swarm, according to the updated speed and position, the value of each particle is calculated again using the weighted objective function, and the value of each particle is compared with the corresponding value of the updated and stored individual optimal value. If the value of the particle is larger, then the corresponding value of the particle, the speed and position of all logical instances replace the individual optimal value of the particle in the updated and stored individual optimal value. After the individual optimal values of all particles are updated, the corresponding values of the individual optimal values of all particles are compared with the updated and stored global optimal value. If the corresponding value of the individual optimal value of a certain particle in the particle swarm is larger, then the updated and stored global optimal value is replaced, so as to realize the update of the global optimal value of the particle swarm. Until the termination condition is reached, the logical instance block division method in the particle corresponding to the current global optimal value is used as the final permanent magnet block division result.

[0110] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. An optimization method for a semi-direct-drive large wind turbine based on permanent magnet segmentation, characterized in that: The semi-direct-drive large-scale wind turbine generator based on permanent magnet block includes: a rotor, the rotor includes a plurality of permanent magnet units distributed along the circumferential direction, each of the permanent magnet units includes a plurality of permanent magnet blocks; The inner layer and the outer layer of the permanent magnet block distributed along the circumferential direction are both provided with grooves, and each groove is evenly distributed on the surface of the permanent magnet block in the radial direction, and the grooves provided in the inner layer and the outer layer are arranged alternately; The optimization method comprises: S1: The length, width and thickness of each magnetic block are taken as geometric parameters, and the number of blocks N is taken as a discrete variable; each sub-block is regarded as a particle; S2: Establish a magnetic field simulation model; (1) Build a 3D permanent magnet motor model; (2) Add excitation, boundary conditions, and meshing; (3) Set the step size and final time for calculation; S3: Configure particle swarm optimization algorithm; Add geometric constraints to ensure that particles are always within the domain and do not exceed the boundaries, and sub-blocks cannot overlap: Add physical constraints to determine the size of the permanent magnet and connect it with engineering practice: Particle encoding and initialization: Normalize the size, position, and magnetization direction of each sub-block to the [0, 1] interval; S4: Iterative optimization; Using the particle swarm optimization algorithm, the speed of each logical instance in each particle in the current particle swarm is updated; After the speed and position of each particle in the particle swarm are updated, the value of each particle is calculated again using the weighted objective function according to the updated speed and position, and the value of each particle is compared with the value corresponding to the updated and stored individual optimal value. If the value of the particle is greater, the value corresponding to the particle and the speed and position of all logical instances replace the updated and stored individual optimal value of the particle. In the particle swarm optimization algorithm, the magnetic field uniformity and energy conversion efficiency are quantified and combined into a single objective function through weighting: α、β is the weight coefficient, Uniformity ( x ) is the magnetic field uniformity function, Efficiency ( x ) is the energy conversion efficiency function, is the weighted objective function.

2. The optimization method of the semi-direct-drive large wind turbine generator based on permanent magnet segmentation as claimed in claim 1 is characterized in that: The wind turbine generator further comprises a rotating shaft, a rotor and a stator are coaxially arranged with the rotating shaft, and an axial air gap exists between the rotor and the adjacent stator; The stator is made of laminated silicon steel sheets, and is punched with evenly distributed slots. Three-phase symmetrical windings are placed in the slots, which are stator windings.

3. The optimization method of the semi-direct-drive large wind turbine generator based on permanent magnet segmentation as claimed in claim 2 is characterized in that: The slot type of the stator is an open slot, and a stator slot wedge is placed at the slot opening; The stator winding is a double-layer winding, the rotor structure is built-in, and the permanent magnet unit is built-in the rotor; The permanent magnet blocks are parallel to each other and perpendicular to the radial direction.

4. The optimization method of the semi-direct-drive large wind turbine generator based on permanent magnet segmentation according to claim 1 is characterized in that: After the individual optimal values ​​of all particles are updated, the values ​​corresponding to the individual optimal values ​​of all particles are compared with the updated and stored global optimal value. If the value corresponding to the individual optimal value of a particle in the particle swarm is larger, the updated and stored global optimal value is replaced, thereby realizing the global optimal value update of the particle swarm until the termination condition is reached. The logical instance partitioning method in the particle corresponding to the current global optimal value is used as the final permanent magnet partitioning result.

5. The optimization method of the semi-direct drive large wind turbine generator based on permanent magnet segmentation as claimed in claim 1, characterized in that the speed The update formula is: t is the number of iterations; i =1, 2, ... are the particle numbers, j is the particle dimension; w is the inertia weight, which controls the global and local balance of the search steps; c 1, c 2 is the learning factor, c 1Control the influence of individual optimality, c 2. Control the impact of global optimality; v ij For particles i history j The speed of generation time; x ij For particles i history j The position of the generation; p best，ij For particles i The best position in history j Coordinates of the generation time; g best，j is the global best position; r 1. r 2 is a random number, which increases the randomness of the algorithm and avoids falling into the local optimum.

6. The optimization method of the semi-direct drive large wind turbine generator based on permanent magnet segmentation according to claim 1 is characterized in that: Magnetic field uniformity function Uniformity ( x ) Use magnetic field standard deviation or maximum deviation quantification, set in the target area M Sampling points, calculate the magnetic induction intensity B k Variance of: in, Uniformity ( x ) is the magnetic field uniformity function; is the average magnetic induction intensity, B k is the air gap flux density, M =1, 2, 3….

7. The optimization method of the semi-direct-drive large wind turbine generator based on permanent magnet segmentation according to claim 1 is characterized in that: The energy conversion efficiency function is defined by the ratio of actual output power to theoretical maximum power. Efficiency : in, Efficiency ( x ) is the energy conversion efficiency function; B is the air gap magnetic density; B max is the maximum air gap magnetic flux density; H is the magnetic field strength; H max is the maximum magnetic field strength, V For volume.

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