Direct drive wind turbine

Abstract

The invention relates to a direct drive wind turbine (160). The wind turbine comprises a generator (3) mounted on a frame (1), the generator (3) comprising a generator stator (32) and a generator rotor (31) configured to rotate about an axis of rotation (RA), the frame (1) having a protrusion (11) extending over the generator (3), the protrusion (11) comprising a first structure and a second structure; wherein the first structure and the second structure are configured to rotate relative to each other and about the axis of rotation (RA); wherein the first structure is attached to the generator stator (32) and the second structure is attached to the generator rotor (31); a brake system (2) is attached to the first structure and the second structure, the brake system (2) being spaced apart from the generator (3) along the axis of rotation (RA). A method (200) for braking a direct drive wind turbine (160) is also disclosed.

Description

Technical Field

[0001] This disclosure relates to a direct-drive wind turbine and a method for braking such a direct-drive wind turbine. Background Technology

[0002] Modern wind turbines are widely used to supply electricity to the power grid. These turbines generally consist of a tower and a rotor mounted on the tower. The rotor (typically consisting of a hub and multiple blades) begins to rotate under the influence of wind on the blades. This rotation generates torque, typically directly (“direct drive” or “driveless”) or through a gearbox, transmitted via the rotor shaft to a generator. In this way, the generator produces electricity that can be supplied to the power grid.

[0003] In conventional wind turbines, a gearbox increases the speed of the wind-driven rotor. This reduces the required size of the generator. In direct-drive generators, typically used in offshore direct-drive wind turbines, the rotor shaft is largely directly connected to the rotor hub. Consequently, direct-drive wind turbines include a generator that operates at the same speed as the rotor with wind turbine blades, and therefore have a much larger diameter than generators used in wind turbines with gearboxes.

[0004] A challenging aspect of direct-drive wind turbines involves the rotor braking system. Because there is no gearbox, a relatively large braking torque is required to reduce the rotor speed; therefore, the characteristics of the braking system must be selected to withstand this braking torque. This problem becomes increasingly important because there is a trend towards larger wind turbines to capture more wind and convert wind energy into electricity. Larger wind turbines may require larger braking torques, and larger braking torques may involve increasing the size of the rotor braking system.

[0005] Due to space constraints, rotor brake systems in direct-drive wind turbines are typically located within the generator to function between the generator stator and rotor. However, the current arrangement of the brake system within the generator limits the dimensions that can be achieved by the brake system.

[0006] Furthermore, regarding the common arrangement of braking systems in generators, if the brake calipers are hydraulic, there is a significant risk of leaking oil reaching the generator's air gaps.

[0007] In addition, the discharge path inside the generator is compromised by brake calipers that conflict with the minimum clearance required by safety standards.

[0008] Furthermore, the availability of components for replacement is significantly reduced due to the presence of a braking system in the generator (especially in the generator).

[0009] This disclosure provides examples of direct-drive wind turbines and methods that at least partially address some of the aforementioned drawbacks.

[0010] Technical Solution 1. A direct-drive wind turbine, comprising:

[0011] A generator, mounted on a frame, includes a generator stator and a generator rotor configured to rotate about an axis of rotation. The frame has a protrusion extending beyond the generator, the protrusion including a first structure and a second structure; wherein the first structure and the second structure are configured to rotate relative to each other and about the axis of rotation; wherein the first structure is attached to the generator stator and the second structure is attached to the generator rotor.

[0012] A braking system, which is attached to the first and second structures, is spaced apart from the generator along the axis of rotation.

[0013] Technical Solution 2. The direct-drive wind turbine according to Technical Solution 1, wherein the protruding portion extends along the rotation axis toward the rotor hub of the wind turbine.

[0014] Technical Solution 3. The direct-drive wind turbine according to technical solutions 1-2, wherein the protruding portion extends along the rotation axis away from the rotor hub of the wind turbine.

[0015] Technical Solution 4. The direct-drive wind turbine according to technical solutions 1-3, wherein the first structure is an internal structure and the second structure is an external structure.

[0016] Technical Solution 5. The direct-drive wind turbine according to Technical Solution 4, wherein the external structure and the internal structure are positioned co-centered around the rotation axis, and the internal structure is positioned between the external structure and the rotation axis.

[0017] Technical Solution 6. The direct-drive wind turbine according to any one of the foregoing technical solutions, wherein the first structure is an external structure and the second structure is an internal structure.

[0018] Technical Solution 7. A direct-drive wind turbine according to any one of technical solutions 1-6, wherein the braking system includes a disc and a caliper, the disc being attached to one of the first structure and the second structure, and the caliper being attached to the other.

[0019] Technical Solution 8. The direct-drive wind turbine according to Technical Solution 7, wherein the disc is attached to the second structure and the caliper is attached to the first structure.

[0020] Technical Solution 9. The direct-drive wind turbine according to Technical Solution 8, wherein the caliper is disposed between the rotation axis and the disk.

[0021] Technical Solution 10. A direct-drive wind turbine according to any one of technical solutions 7-9, wherein the caliper has a U-shaped cross-section for receiving the cross-section of the disk, and the cavity defined by the U-shaped cross-section of the caliper faces outward from the axis of rotation.

[0022] Technical Solution 11. The direct-drive wind turbine according to Technical Solution 8, wherein the disk is attached to the second structure via a spacer.

[0023] Technical Solution 12. A direct-drive wind turbine according to any one of the foregoing technical solutions, wherein the braking system is positioned at the distal end of the protruding portion, the distal end of the protruding portion being positioned away from the generator along the axis of rotation.

[0024] Technical Solution 13. A direct-drive wind turbine according to any one of technical solutions 7-11, wherein the caliper is effectively connected to the generator stator via the first structure of the frame, and the disc is effectively connected to the generator rotor via the second structure.

[0025] Technical Solution 14. The direct-drive wind turbine according to Technical Solution 2, wherein the first structure has a tapered region toward the rotor hub, and the second structure is rotatably mounted on the tapered region.

[0026] Technical Solution 15. A method for braking a direct-drive wind turbine, the direct-drive wind turbine including a rotor hub, a generator mounted on a frame, and a braking system, the frame having a protrusion extending beyond the generator, the protrusion including a first structure and a second structure configured to rotate relative to each other about an axis of rotation, wherein the first structure is attached to a generator stator, and the second structure is attached to a generator rotor, the braking system is attached to the first structure and the second structure, and the braking system is spaced apart from the generator along the axis of rotation; the method includes:

[0027] The target rotational speed of the rotor hub is determined at the controller of the wind turbine;

[0028] The rotational speed of the rotor hub is adjusted to the target rotational speed by controlling the frictional force applied by the braking system. Summary of the Invention

[0029] In one aspect, a direct-drive wind turbine is provided. The direct-drive wind turbine includes a generator mounted on a frame, the generator including a generator stator and a generator rotor configured to rotate about an axis of rotation, the frame having a protrusion extending beyond the generator, the protrusion including a first structure and a second structure. The first and second structures are configured relative to each other and to rotate about an axis of rotation. The first structure is attached to the generator stator, and the second structure is attached to the generator rotor. The direct-drive wind turbine further includes a braking system attached to the first and second structures, the braking system being spaced apart from the generator along the axis of rotation.

[0030] In this respect, the typical space limitations or constraints of generators can be avoided. It facilitates the integration of braking systems within direct-drive wind turbines. The size of braking systems (e.g., calipers) can also be increased, and thus the braking torque obtained can be increased. Consequently, direct-drive wind turbines can be designed with relatively larger dimensions to capture more wind and convert wind energy into electricity.

[0031] Furthermore, the venting path inside the generator will not be compromised by the braking system in direct-drive wind turbines in this respect, because the required minimum clearance can be achieved. Therefore, the safety situation can be improved.

[0032] Furthermore, since the braking system can be isolated from the generator, the risk of leaking oil reaching the generator's air gap can be avoided.

[0033] Additionally, improved accessibility to component replacement (especially generators) in direct-drive wind turbines is possible. This could mean easier maintenance or repair tasks and reduced time involved.

[0034] As a result of this first feature, the efficiency of the operators inside the cabin is also improved.

[0035] On the other hand, a method for braking a direct-drive wind turbine is provided. The wind turbine includes a rotor hub, a generator mounted on a frame, and a braking system. The frame has a protrusion extending beyond the generator, the protrusion including a first structure and a second structure configured to rotate relative to each other about a rotational axis. The first structure is attached to the generator stator, and the second structure is attached to the generator rotor. The braking system is attached to the first and second structures and is spaced apart from the generator along the rotational axis. The method includes: determining a target rotational speed of the rotor hub at a controller of the wind turbine; and adjusting the rotational speed of the rotor hub to the target rotational speed by controlling a frictional force applied by the braking system.

[0036] In another aspect, a direct-drive wind turbine is provided. The direct-drive wind turbine includes: a rotor hub having a hollow body; a generator mounted on a frame about a rotation axis, the generator having a generator rotor and a generator stator. The frame has a protrusion extending through the generator into the hollow body of the rotor hub. The protrusion includes: a fixed internal structure attached to the generator stator; and an external structure configured to rotate about the rotation axis and attached to the generator rotor. The direct-drive wind turbine further includes: a braking system comprising: a disc attached to one of the external and internal structures; and a caliper attached to the other of the external and internal structures.

[0037] The advantages derived from this aspect are similar to those mentioned regarding the direct-drive wind turbines of the first aspect. Attached Figure Description

[0038] Non-limiting examples of this disclosure will be described below with reference to the accompanying drawings, in which:

[0039] Figure 1 A perspective view of a wind turbine based on an example is shown;

[0040] Figure 2 A simplified internal cross-sectional view of the nacelle and rotor hub of a wind turbine according to an example is shown.

[0041] Figure 3 An example is shown. Figure 1 Perspective and detail view of the protruding part of the frame of a wind turbine;

[0042] Figure 4 A braking system based on an example is shown. Figure 1 A partial cross-sectional view of the protruding portion of the wind turbine's frame; and

[0043] Figure 5 A flowchart is shown for a method of braking a direct-drive wind turbine according to an example. Detailed Implementation

[0044] In these figures, the same reference symbols have been used to identify matching elements.

[0045] Figure 1 A perspective view of an example wind turbine 160 is shown. As illustrated, the wind turbine 160 includes: a tower 170 extending from a support surface 150; a nacelle 161 mounted on the tower 170; and a rotor 115 coupled to the nacelle 161. The rotor 115 includes a rotatable rotor hub 110 and at least one rotor blade 120 coupled to and extending outward from the rotor hub 110. For example, in the illustrated example, the rotor 115 includes three rotor blades 120. However, in alternative embodiments, the rotor 115 may include more or fewer than three rotor blades 120. Each rotor blade 120 may be spaced apart from the rotor hub 110 to facilitate rotation of the rotor 115 so that kinetic energy can be converted from wind power into usable mechanical energy, and subsequently into electrical energy. For example, the rotor hub 110 may be rotatably coupled to an electric generator 3 located within or forming part of the nacelle 161. Figure 2 ), to allow the generation of electrical energy.

[0046] The wind turbine 160 may also include a wind turbine controller 180, which is centrally located within the nacelle 161. However, in other examples, the wind turbine controller 180 may be located within any other component of the wind turbine 160 or at a location external to the wind turbine. Furthermore, the controller 180 may be communicatively coupled to any number of components of the wind turbine 160 to control the operation of such components.

[0047] Figure 1 The wind turbine 160 can be placed in offshore or onshore locations.

[0048] The wind turbine controller 180 may include one or more processors and associated one or more memory devices configured to perform a variety of computer-performed functions (e.g., performing methods, steps, operations, and the like and storing related data, as disclosed herein). The wind turbine controller can perform various functions, such as receiving, transmitting, and / or executing wind turbine control signals and controlling the overall operation of the wind turbine. The wind turbine controller can be programmed to control overall operation based on information received from sensors indicating, for example, load, wind speed, wind direction, turbulent disruption of components, and other parameters.

[0049] As used herein, the term "processor" refers not only to integrated circuits included in a computer as understood in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Processors are also configured to compute advanced control algorithms and transmit them to a wide variety of Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). Additionally, one or more memory devices may include one or more memory elements (including, but not limited to, computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, optical disc read-only memory (CD-ROM), magneto-optical disks (MOD), digital versatile discs (DVDs), and / or other suitable memory elements). Such one or more memory devices may be configured to store suitable computer-readable instructions that, when executed by one or more processors, configure the controller to perform the various functions described herein.

[0050] Figure 2 A simplified internal cross-sectional view of the nacelle 161 and rotor hub 110 of a wind turbine according to an example is shown. For clarity, some components of the wind turbine 160 are not shown. As illustrated, a generator 3 can be coupled to the rotor hub 110 of the wind turbine 160 to generate electricity from the generated rotational energy. Thus, the rotation of the rotor hub 110 drives the generator 3.

[0051] It should be understood that the frame 1 and generator 3 can be generally supported within the nacelle 161 by a support frame or base plate 17 positioned on top of the wind turbine tower 170. The nacelle 161 is rotatably connected to the tower 170. The base plate 17 can be rotatably connected to the wind turbine tower.

[0052] According to one side, it was disclosed that... Figure 1 and Figure 2 A direct-drive wind turbine 160. The wind turbine 160 includes a generator 3 mounted on a frame 1. The generator 3 includes a generator stator 32 and a generator rotor 31, the generator rotor 31 being configured to rotate about a rotation axis RA. The frame 1 has a protrusion 11 extending beyond the generator 3. The protrusion 11 includes a first structure and a second structure. The first structure and the second structure are configured relative to each other and to rotate about the rotation axis RA. The first structure is attached to the generator stator 32, and the second structure is attached to the generator rotor 31. The wind turbine 160 further includes a braking system 2, which is attached to the first structure and the second structure. The braking system is spaced away from the generator 3 along the rotation axis RA.

[0053] As used in this article, the terms "first structure" and "second structure" are interchangeable.

[0054] exist Figure 2 In the example shown, the protrusion 11 extends along the rotation axis RA toward the rotor hub 110 of the wind turbine 160. Thus, the protrusion 11 can extend along the rotation axis RA in the upwind direction.

[0055] In another example, the protrusion 11 may extend along the axis of rotation RA away from the rotor hub 110 of the wind turbine 160. The protrusion 11 may extend toward the base plate 17 or the tower 170, that is, the protrusion 11 may be positioned along the axis of rotation RA in a direction opposite to that of the rotor hub 110. Therefore, the protrusion 11 may extend along the axis of rotation RA in a downwind direction.

[0056] The distance 50 can be limited between the generator 3 and the braking system 2, that is, the braking system 2 can be placed separately from the generator 3 or even the housing or cover of the generator 3. Figure 2 The distance 50 is clearly visible in the image, where the brake system 2 is positioned at the distal end 19 of the protrusion 11, which is positioned away from the generator 3 along the axis of rotation RA. The distance 50 can also be defined when the protrusion 11 extends toward the base plate 17 or the tower 170.

[0057] refer to Figure 2 The protruding part 11 can be the front part of the frame 1. In this case, the frame 1 can have a rear part 16, which faces the base plate 17 of the wind turbine 160.

[0058] In one example, the first structure could be the inner structure 13, and the second structure could be the outer structure 12. This allows for... Figure 2 See the example in [link to example]. In another example, the first structure can be the outer structure, and the second structure can be the inner structure. In both examples, the inner and outer structures can rotate relative to each other and about the axis of rotation RA.

[0059] According to one example of a direct-drive wind turbine 160, the external structure 12 can be effectively connected to the rotor hub 110 via the generator rotor 31. The latter can be connected, for example, via... Figure 2 A series of bolts 4 are shown. The bolts 4 connect the rotor hub 110, the outer structure 12, and the generator rotor 31 in such a way that at least a portion of the generator rotor 31 is sandwiched between the rotor hub 110 and the outer structure 12. This exemplary connection allows the rotational motion of the rotor hub 110 to be transmitted through the generator rotor 31 to the outer structure 12. Conversely, if the outer structure 12 is braked, for example, the generator rotor 31 and the rotor hub 110 can also be braked.

[0060] In another example, the joint can be achieved using any fastener available on the market or even by welding.

[0061] like Figure 2 As shown, the first structure may have a tapered region 18 facing the rotor hub 110. The second structure may be rotatably mounted on the tapered region 18, i.e., the second structure is rotatable about the rotation axis RA and the first structure. The tapered region 18 may protrude from the generator 3 at least partially towards the rotor hub 110.

[0062] As shown, the direct-drive wind turbine 160 may additionally include a pair of bearings 15 between the second structure (e.g., outer structure 12) and the first structure (e.g., inner structure 13). The pair of bearings 15 may be spaced apart from each other along the axis of rotation RA. Alternatively, a single bearing may allow the first and second structures to be rotatably connected.

[0063] Next, refer to Figure 2 For example, at least a portion of the protrusion 11 may be placed in a chamber 111 defined inside the rotor hub 110. The chamber 111 may provide sufficient space to select a brake system 2 with a significantly large size. The chamber 111 may be defined as a hollow body of the rotor hub 110.

[0064] exist Figure 2 In this embodiment, the generator rotor 31 surrounds the generator stator 32. However, in other examples, the generator stator may surround the generator rotor. In these other examples, the generator rotor may be associated with a rotor hub, and the stator generator may be associated with an internal structure, as in any of the examples disclosed herein concerning a generator rotor surrounding a generator stator.

[0065] Figure 3 An example is shown. Figure 1 Perspective and detail views of the protruding parts of the wind turbine frame. (Example) Figure 2 and Figure 3 As shown, the outer structure 12 and the inner structure 13 are co-centered around the rotation axis RA, with the inner structure 13 positioned between the outer structure 12 and the rotation axis RA. Although Figure 2 The example shown illustrates an outer structure 12 and an inner structure 13 having a drum-like shape, but alternatively, the outer structure 12 as a second structure or the inner structure 13 as a first structure can be formed by a plurality of connecting arms arranged around the axis of rotation RA.

[0066] Figure 4 A braking system based on an example is shown. Figure 1 A partial cross-sectional view of the protruding part of the frame of a wind turbine.

[0067] In one example, the braking system 2 may include a disc 21 and a caliper 22, the disc 21 being attached to one of a first structure and a second structure, and the caliper 22 being attached to the other. In a specific example, the disc 21 may be attached to the second structure, and the caliper 22 may be attached to the first structure. In both cases, the disc 21 may be generally "ring-shaped" and may be made of a metallic material or the like.

[0068] Now for reference Figure 3 and Figure 4 As can be seen in the example, disk 21 is attached to external structure 12, and caliper 22 is attached to internal structure 13. In another example, disk 21 may be attached to internal structure 13, and caliper 22 may be attached to external structure 12.

[0069] In some other examples, the braking system 2 may have multiple calipers provided circularly around the axis of rotation RA. The calipers 22 may be uniformly positioned relative to the disc 21. The calipers 22 may have a plurality of pads configured to generate friction between the calipers 22 and the disc 21 to at least reduce, maintain, or increase the rotational speed of the outer structure 12. Thus, the calipers can clamp the disc 21. Consequently, the outer structure 12 may rotate substantially faster, slower, or at a constant speed.

[0070] Furthermore, the braking system 2 can be used as a stationary parking brake to substantially prevent rotational movement of the outer structure 12 relative to the inner structure 13. In this case, the rotational speed of the outer structure 12 can remain constant and is substantially zero.

[0071] Furthermore, the braking system 2 can be used to control the rotational movement of the outer structure 12 relative to the inner structure 13. For example, a substantially constant rotational speed of the outer structure 12 can be generated.

[0072] like Figure 3 As shown, the caliper 22 can be positioned between the rotation axis RA and the disk 21. In this way, the diameter of the disk 21 can increase outward from the rotation axis RA. The size of the caliper 22 can be selected to match the cross-sectional dimensions of the larger disk 21.

[0073] In the example of the direct-drive wind turbine 160, the caliper 22 can be effectively connected to the generator stator 32 via a first structure of the frame 1, and the disc 21 can be effectively connected to the generator rotor 31 via a second structure. In this way, the braking system 2 can act on the generator rotor 31. When the braking system 2 is in operation, it may cause the generator rotor 31 to slow down.

[0074] In another example, the disc 21 may be positioned between the rotation axis RA and the caliper 22. In this example, the disc 21 may be attached to the internal structure 13, and the caliper 22 may be attached to the external structure 12.

[0075] Next, refer to Figure 3 and Figure 4 For example, the caliper 22 may have a U-shaped cross-section for receiving the cross-section of the disc 21. The cavity 24 defined by the U-shaped cross-section of the caliper 22 may face outward from the axis of rotation RA. The cavity 24 may receive at least a portion of the cross-section of the disc 21.

[0076] Now for reference Figure 4 The disc 21 can be attached to the second structure via the spacer 23. The distance 50 can be increased by the gap 51 between the disc 21 and the second structure (e.g., the outer structure 12). The spacer 23 can further increase the distance 50 between the brake system 2 and the generator 3. The spacer 23 can be selected to adjust the clearance between the protrusion 11 and the brake system 2 along the axis of rotation RA. The increased clearance allows for the installation of a larger brake system 2, especially a larger caliper 22.

[0077] In some examples, the brake system 2 may be driven by a hydraulic system to act on the pads of the caliper 22 to apply pressure to the disc 21. The hydraulic system may have a pump, accumulator, or the like in fluid communication with a piston for applying force to the pads. To control the brake system 2, the controller 180 may send commands to the pump or accumulator to increase or decrease or maintain the pressure of the fluid in the hydraulic system, and thus transfer pressure from the fluid to the piston, and therefore to the pads of the caliper 22.

[0078] In an alternative example, the brake system 2 can be based on electromechanical technology. Instead of a hydraulic system, an electric actuator connected to the caliper 22 can receive corresponding commands from the controller 180 to control the frictional force applied to the disc 21, and thus control the rotational speed of the external structure 12.

[0079] Figure 5 A flowchart illustrates a method 200 for braking a direct-drive wind turbine according to an example. The wind turbine 160 may be... Figure 1 or Figure 2 The wind turbine shown is, and therefore, wind turbine 160 includes wind turbine controller 180.

[0080] According to one aspect, a method 200 for braking a direct-drive wind turbine 160 is provided. The wind turbine 160 includes a rotor hub 110 mounted on a frame 1 and a generator 3. The wind turbine 160 further includes a braking system 2. The frame has a protrusion 11 extending over the generator 3. The protrusion 11 includes a first structure and a second structure configured to rotate relative to each other and about a rotation axis RA. The first structure is attached to a generator stator 32, and the second structure is attached to a generator rotor 31. The braking system 2 is attached to the first structure and the second structure, and the braking system 2 is spaced away from the generator 3 along the rotation axis RA. The method 200 includes determining 201 a target rotational speed of the rotor hub 110 at a controller 180 of the wind turbine 160. The method 200 further includes adjusting 202 the rotational speed of the rotor hub 110 to the target rotational speed by controlling the frictional force applied by the braking system 2.

[0081] In some examples of method 200, it may additionally include using calipers to apply a frictional force to the disc 21 attached to the second structure until the rotation of the rotor hub 110 stops. The rotation may stop about the axis of rotation RA.

[0082] Braking torque can be obtained stepwise or continuously using method 200.

[0083] In demonstrative operation, the rotational motion of the rotor hub 110 can be transmitted to the generator rotor 31 because the rotor hub 110 and the generator rotor 31 can be fastened together by bolts 4. The amount of rotational motion of the rotor hub 110 around the axis of rotation RA (e.g., one revolution) likely implies the same amount of rotational motion of the generator rotor 31, since this is a direct-drive wind turbine 100. The external structure 12 can also rotate with the same amount of rotational motion because the external structure 12 is attached to the generator rotor 31, for example, by bolts 4. Thus, the external structure 12 can rotate relative to the internal structure 13. Figure 2 or Figure 3 In the example, disk 21 is attached to external structure 12, and caliper 22 is attached to internal structure 13. Therefore, if rotor hub 110 rotates about axis of rotation RA, disk 21 will also rotate.

[0084] The controller 180 determines the target rotational speed of the rotor hub 110. The rotational speed of the rotor hub 110 can be compared with the target rotational speed, for example, by the controller 180. Depending on this comparison, the frictional force on the disc 21 controlled by the controller 180 can be decreased, increased, or maintained. As an example, if the difference between the rotational speed of the rotor hub 110 and the target rotational speed is outside a predetermined range, the controller 180 can trigger the brake system 2 to substantially increase or decrease the frictional force on the disc 21 to adjust the rotational speed. If the difference between the rotational speed of the rotor hub 110 and the target rotational speed is within a predetermined range, the controller 180 can trigger the brake system 2 to substantially maintain the frictional force on the disc 21.

[0085] The caliper 22 can apply pressure to the disc 21 to generate friction. Therefore, depending on the friction generated between the disc 21 and the caliper 22, the rotational speed of the generator rotor 31 and the external structure 12 can be increased, decreased, maintained, or even stopped. Depending on the amount of pressure applied to the disc 21, the rotational speed of the rotor hub 110 can be adjusted (e.g., increased, maintained, decreased, or even stopped). Increased friction may mean a decrease in rotational speed, decreased friction may mean an increase in rotational speed, and constant friction may mean a constant rotational speed.

[0086] The above exemplary braking operation has described two scenarios: In the first scenario, the rotor 115 has already rotated about the axis of rotation RA, and then the brake system 2 is actuated. In the second scenario, the brake system 2 can be actuated when the rotor 115 has already stopped, or at least when there is essentially no defined rotational motion. The latter may occur, for example, when the wind turbine 2 is damaged or requires maintenance. In this way, the stopped state of the rotor 115 can be guaranteed.

[0087] According to another aspect, a direct-drive wind turbine 160 is provided. The wind turbine 160 of this aspect includes: a rotor hub 110 having a hollow body; and a generator 3 mounted on a frame 1 about a rotation axis RA. The generator 3 has a generator rotor 31 and a generator stator 32. The frame 1 has a protrusion 11 extending over the generator 3 into the hollow body of the rotor hub 110. The protrusion 11 includes a fixed internal structure 13 attached to the generator stator 32. The protrusion 11 further includes an external structure 12 configured to rotate about the rotation axis RA and attached to the generator rotor 31. The direct-drive wind turbine 160 further includes a braking system 2, which includes: a disc 21 attached to one of the external structure 12 and the internal structure 13; and a caliper 22 attached to the other of the external structure 12 and the internal structure 13.

[0088] In one example, disk 21 can be attached to external structure 12, and caliper 22 can be attached to internal structure 13. In another example, disk 21 can be attached to internal structure 13, and caliper 22 can be attached to external structure 12.

[0089] According to one example of this aspect, the outer structure 12 and the inner structure 13 can be positioned co-centered about the axis of rotation RA, and the inner structure 13 can be positioned between the outer structure 12 and the axis of rotation RA.

[0090] In another example, the internal structure may have a tapered region 18 of a hollow body facing the rotor hub 110, and the external structure 12 may be rotatably mounted on the tapered region.

[0091] In another example, the brake system 2 can be spaced away from the generator 3 along the rotation axis RA.

[0092] This written description uses examples (including preferred embodiments) to disclose the invention and also enables any person skilled in the art to practice the invention (including making and using any apparatus or system and performing any incorporated methods). The scope of the invention is defined by the claims and may include other examples as would be expected by a person skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that have a non-substantial difference from the literal language of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspect, can be mixed and matched by a person skilled in the art to construct additional embodiments and techniques in accordance with the principles of this application. If reference numerals relating to the drawings are enclosed in parentheses in the claims, these reference numerals are merely for the purpose of improving the comprehensibility of the claims and should not be construed as limiting the scope of the claims.

Claims

1. A direct-drive wind turbine (160), comprising: A generator (3) is mounted on a frame (1), the generator (3) including a generator stator (32) and a generator rotor (31) configured to rotate about a rotation axis (RA), the frame (1) having a protrusion (11) extending beyond the generator (3), the protrusion (11) including a first structure, a second structure and one or more bearings connecting the first structure and the second structure, wherein the first structure and the second structure are configured to rotate relative to each other and about the rotation axis (RA); wherein the first structure is attached to the generator stator (32) and the second structure is attached to the generator rotor (31); A braking system (2) is attached to the first structure and the second structure, the braking system (2) being spaced away from the generator (3) along the axis of rotation (RA).

2. The direct-drive wind turbine (160) according to claim 1, wherein, The protruding portion (11) extends along the axis of rotation (RA) toward the rotor hub (110) of the wind turbine.

3. The direct-drive wind turbine (160) according to claim 1, wherein, The protruding portion (11) extends along the axis of rotation (RA) away from the rotor hub (110) of the wind turbine.

4. The direct-drive wind turbine (160) according to any one of claims 1-3, wherein, The first structure is an internal structure (11), and the second structure is an external structure (12).

5. The direct-drive wind turbine (160) according to claim 4, wherein, The external structure (12) and the internal structure (13) are co-centered around the axis of rotation (RA), with the internal structure (13) positioned between the external structure (12) and the axis of rotation (RA).

6. The direct-drive wind turbine (160) according to any one of claims 1-3, wherein, The first structure is an external structure, and the second structure is an internal structure.

7. The direct-drive wind turbine (160) according to any one of claims 1-3, wherein, The braking system (2) includes a disc (21) and a caliper (22), the disc (21) being attached to one of the first and second structures, and the caliper (22) being attached to the other.

8. The direct-drive wind turbine (160) according to claim 7, wherein, The disc (21) is attached to the second structure, and the caliper (22) is attached to the first structure.

9. The direct-drive wind turbine (160) according to claim 8, wherein, The caliper (22) is positioned between the rotation axis (RA) and the disk (21).

10. The direct-drive wind turbine (160) according to claim 7, wherein, The caliper (22) has a U-shaped cross-section for receiving the cross-section of the disc (21), and the cavity (24) defined by the U-shaped cross-section of the caliper (22) faces outward from the axis of rotation (RA).

11. The direct-drive wind turbine (160) according to claim 8, wherein, The disk (21) is attached to the second structure (12) via a spacer (23).

12. The direct-drive wind turbine (160) according to any one of claims 1-3, wherein, The brake system (2) is positioned at the distal end of the protrusion (11), which is positioned away from the generator (3) along the axis of rotation (RA).

13. The direct-drive wind turbine (160) according to claim 7, wherein, The caliper (22) is effectively connected to the generator stator (32) via the first structure of the frame (1), and the disc (21) is effectively connected to the generator rotor (31) via the second structure.

14. The direct-drive wind turbine (160) according to claim 2, wherein, The first structure has a tapered region (18) toward the rotor hub (110), and the second structure is rotatably mounted on the tapered region (18).

15. A method (200) for braking a direct-drive wind turbine (160) according to any one of claims 1-14, the method comprising: The target rotational speed of the rotor hub (110) is determined (201) at the controller (180) of the wind turbine (160); The rotational speed of the rotor hub is adjusted (202) to the target rotational speed by controlling the frictional force applied by the brake system (2).

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