Single sided brake system for wind turbine generators

Abstract

The present invention relates to a generator (100) for a wind turbine (150). The generator (100) comprises a rotor (110) comprising a drive end side to which a hub (151) of a wind turbine (150) is coupleable, a stator (120) to which the rotor (110) is rotatably mounted around a rotating axis (107), and a holding brake system (130) mounted to the rotor (110) and the stator (120), wherein the holding brake system (130) comprising a brake section (131) and a brake pad (132). The brake section (131) comprises one braking side having a braking surface (201) onto which the brake pad (132) is pressable for generating a braking force by friction to hold the rotor (110) in a non-rotating parking position.

Description

[0001] 2024PF00559

[0002] 1

[0003] DESCRIPTION

[0004] Single Sided Brake System for Wind Turbine Generators

[0005] Field of the invention

[0006] The present invention relates to a generator for a wind turbine, specifically designed to incorporate a holding brake system for maintaining the rotor in a non-rotating parking position. Furthermore, the invention relates to a wind turbine and to a method of controlling a parking position of a wind turbine .

[0007] Art background

[0008] In the field of wind turbines, it is common to utilize generators that convert mechanical energy from wind into electrical energy. These generators typically have a rotor and a stator, with the rotor being driven by the wind turbine ' s blades . To ensure safe operation and maintenance, it is crucial to have an effective brake system that can hold the rotor in a non-rotating position when necessary. Known systems often incorporate complex braking mechanisms that involve multiple components and intricate designs to achieve the desired braking force .

[0009] Hence, in the field of wind turbine brake systems, there remains a need for more efficient and reliable solutions .

[0010] Summary of the invention

[0011] It may be an obj ect of the present invention to provide a brake system for generators of wind turbines that is more efficient and reliable .2024PF00559

[0012] 2

[0013] In order to achieve the obj ect defined above, a generator for a wind turbine, a wind turbine and a method of controlling a parking position of a wind turbine according to the independent claims are provided.

[0014] According to a first aspect of the invention, a generator for a wind turbine is described. The generator comprises a rotor, which includes a drive end side that can be coupled to a hub of the wind turbine . The rotor is rotatably mounted around a rotating axis to a stator . A holding brake system is mounted to both the rotor and the stator . The holding brake system includes a brake section and a brake pad. The brake section has one (in particular only one) braking side with a braking surface onto which the brake pad can be pressed to generate a braking force by friction, thereby holding the rotor in a non-rotating parking position.

[0015] According to a further aspect, a wind turbine comprising a hub to which at least a blade for generating lift is coupled, and a generator as described above . The generator comprises a rotor with a drive end side coupled to the hub . This coupling mechanism ensures that the rotor can effectively transmit the mechanical energy generated by the rotating blades to the generator, thereby converting it into electrical energy. The stator, to which the rotor is rotatably mounted around a rotating axis, provides a stationary magnetic field that interacts with the rotor to facilitate the generation of electricity. The holding brake system comprises a brake section and a brake pad, where the brake section features one, in particular only one, braking side with a braking surface . The brake pad is pressable onto this surface to generate a braking force through friction, effectively holding the rotor in a non-rotatable parking position.

[0016] According to a further aspect, a method of controlling a parking position of a wind turbine as described above is presented. The method comprises pressing the brake pad onto the braking surface of the braking side of the brake section2024PF00559

[0017] 3

[0018] for generating a braking force by friction to hold the rotor in a non-rotatable parking position.

[0019] The generator of the wind turbine converts mechanical energy taken from wind into electrical energy. Specifically, the rotor is the rotating part of the generator that converts mechanical energy into electrical energy. The stator is the stationary part that supports the rotor and contains the windings where the electrical energy is induced.

[0020] The generator may be designed to be used in large on-shore or off-shore wind turbines, wherein the stator is an inner stator surrounded by the outer rotor . Hence, the generator may be a direct drive (DD) permanent magnet (PM) generator without using e . g. gear devices, so that higher torque densities result in a higher wind turbine output power .

[0021] The stator comprises the respective parts of the generator that are non-movable, such as the stationary supporting shaft, stator plates and supporting structures for carrying the generator windings . In an exemplary embodiment, the stator device may be an outer stator surrounding an inner rotatable rotor device . As described above, specifically in direct drive wind turbines, the generator comprises an inner stator as surrounded by an outer rotor .

[0022] The rotor comprises the movable parts of the generator and rotates with a rotating axis around the stator . A hub of a wind turbine is coupled to the rotor, so that wind force acting on the blades mounted to the hub drives the rotation of the rotor . The rotating axis of the rotor defines the axial direction of the generator . A radial direction is defined perpendicular to the axial direction and crossing the rotary axis . The circumferential direction is defined2024PF00559

[0023] 4

[0024] perpendicular to the axial direction and the radial direction. Specifically, the rotating axis of the generator may be slightly inclined with respect to a horizontal axis, so that the lift generated by blades of the wind turbine has a vertical direction component which may be beneficial for the structure of the wind turbine during operation.

[0025] The holding brake system is a mechanism designed to keep the rotor stationary when the wind turbine is not in operation, for example during low wind or during maintenance operations . The brake section and brake pad work together to create friction, which is the force that stops the rotor from rotating .

[0026] The holding brake system is defined as a single sided holding brake system. This means that the brake section has one (in particular only one) side with a braking surface, onto which the brake pad is pressed to create the necessary frictional force for holding the rotor in a non-rotating parking position .

[0027] The brake section is formed for example on a structural part of the rotor, such as a rotor disk, or to a stator . The brake section may be an integral part of a structural part and may be formed e . g. by a specific surface treatment or coating on a structural part . Furthermore, a brake disk element may be mounted to the structural part, wherein the brake disk element may have a mounting surface, by which the rotor brake disk element is mounted to the structural part, and an opposed braking surface against which the brake pads may be pressed .

[0028] The brake section may be formed as a ring section running in circumferential direction all around the rotary axis .

[0029] Alternatively, the brake section may be formed of spaced sub2024PF00559

[0030] 5

[0031] sections being arranged along the circumferential direction around the rotary axis .

[0032] The brake pad is a component of the holding brake system that is pressable, actively by an actuator or passively by movement of the rotor and stator structure, onto the braking surface of the brake section. The brake pads are attached to the stator structure, e . g. to the stator plates or to a separate support plate, or to the rotor . When pressed against the braking surface, the brake pad generates a braking force through friction, which is used to hold the rotor in a stationary position. The design of the brake pad and its interaction with the braking surface ensures an effective braking performance and maintaining the rotor in a nonrotating state . The holding brake system may comprise at least one brake pad. In an exemplary embodiment, a plurality of brake pads is provided spaced apart from each other along the circumferential direction. Hence when the brake pads, and e . g. their actuators, are equally spaced ovalization loads acting on the rotor (i . e . the rotor disk) may be reduced.

[0033] The single sided brake system according to the present invention simplifies the braking mechanism by eliminating the need for complex brake systems, having e . g. a conventional brake disk with two opposed braking surfaces against which two opposed pads of a brake caliper have to be pressed. By the single sided brake system the complexity and cost associated with the system are reduced. The single-sided brake system is advantageous because it simplifies the braking mechanism, reduces material requirements, and lowers overall costs by eliminating the need for complex hydraulic systems and reducing the structural load on the generator components .

[0034] According to a further exemplary embodiment, the brake section is provided at a movable rotor structure of the rotor and the brake pad is arranged at a stationary stator structure of the stator . The brake section being part of the2024PF00559

[0035] 6

[0036] movable rotor structure means that it rotates with the rotor, thus ensuring that the braking force is applied directly to the rotating component . On the other hand, the brake pad being part of the stationary stator structure ensures that the braking force is applied in a stable and controlled manner, as the stator does not rotate . This configuration enhances the efficiency and reliability of the brake system by ensuring that the frictional force needed to hold the rotor in a non-rotating position is applied consistently and effectively. When the brake pad is pressed onto the braking surface, the friction generated between these two components creates the necessary braking force . By having the brake section on the movable rotor and the brake pad on the stationary stator, the system benefits from a simplified design that reduces the potential for mechanical failure and enhances the overall durability of the generator ' s brake system.

[0037] According to a further exemplary embodiment, the movable rotor structure comprises a rotor disk being rotatable around the rotating axis . The rotor disk may have a ring shape and extends in radial direction between a bearing device, by which the rotor is rotatable to the stator and the stator shaft, respectively, and an outer rotor housing, extending spaced apart from the rotating axis . The outer rotor housing may form a tube-like shape enveloping the stator and the stator windings, respectively. The outer rotor housing supports the permanent magnets interacting with the stator windings .

[0038] This rotor disk enhances the structural integrity and rotational efficiency of the rotor, ensuring that the rotor can achieve and maintain the necessary rotational speeds for optimal energy generation. The rotor disk also provides a stable and controlled interface for the holding brake system, ensuring that the brake pad can effectively press against the braking surface to generate the required braking force by friction .2024PF00559

[0039] 7

[0040] According to a further exemplary embodiment the braking surface comprises a normal comprising an axial direction component of the rotating axis . The normal is either parallel to the axial direction of the rotating axis or comprises an angle to the axial direction between 1 degree to 45 degrees . By specifying that the normal of the braking surface comprises an axial direction component, the implementation describes a particular geometric relationship between the braking surface and the rotating axis . This relationship affects the distribution of the braking force and the overall stability of the rotor when it is in the non-rotating parking position. The option for the normal to be parallel to the axial direction leads to a direct alignment which might facilitate straightforward application of the braking force, potentially enhancing the simplicity and reliability of the braking mechanism. Alternatively, allowing for an angle between 1 degree to 45 degrees introduces flexibility in the design and provides an absorption of the braking force in direction to the stator shaft . Furthermore, the angular range provides a balance between maintaining and absorbing effective braking force application and allowing for design variations that might be necessary due to space constraints or other engineering considerations .

[0041] According to a further exemplary embodiment, the generator further comprises a bearing device for supporting the rotor rotatably to the stator, wherein the bearing device comprises a stationary bearing ring being mounted to the stator, in particular a stator shaft, and a rotatable bearing ring being mounted to the rotor . The brake section is provided at the rotatable bearing ring of the bearing device . The bearing device may be a rolling bearing, a plain bearing or a fluid film bearing.

[0042] The stationary bearing ring, being affixed to the stator, provides a stable base, while the rotatable bearing ring, attached to the rotor, allows for the necessary rotational2024PF00559

[0043] 8

[0044] freedom. The stationary bearing ring is mounted in particular to the stationary shaft of the generator . The rotatable bearing ring is for example mounted to an inner opening of the rotor disk so that forces introduced into the rotor by the wind force acting on the blades and also weight forces of the hub and the rotor housing are forwarded via the rotatable bearing ring to the stationary bearing ring and further to the structural parts of the stator . From the stator, the forces may be further transferred to other parts of the wind turbine, such as the bedframe at the tower of the wind turbine . Hence, by forming the brake section at the rotatable bearing ring, the braking forces are generated closest to the rotating axis so that braking torque is minimized.

[0045] According to a further exemplary embodiment, the brake pad is arranged at the stationary bearing ring. Alternatively, the brake pad is arranged either at a casting of the fixed shaft of the stator or a stator plate of the stator . By arranging the brake pad at the stationary bearing ring, the casting of the fixed shaft, or the stator plate, the design ensures that the brake pad remains stationary and can reliably press against the braking surface of the brake section. This positioning reduces the likelihood of misalignment or movement of the brake pad during operation.

[0046] In a first alternative, the brake pad is arranged at the stationary bearing ring. For example, an actuator of the brake pad may be placed inside of the fixed stationary shaft and is pushing the brake pads outwards onto the movable rotatable bearing ring (e . g. a respective raceway of the bearing) .

[0047] In the second alternative the brake pads (and e . g. its actuators) are mounted to a mounting point on the stator plate . Hence, the brake pads push from the radially outer side onto the radially outer surface (or side surface) of the rotatable bearing ring mounted to the rotor . The rotatable bearing ring may comprise a respective radially outer surface2024PF00559

[0048] 9

[0049] or axially inner side surface, where a braking surface is machined onto the bearing ring surface . The rotatable bearing ring may comprise a respective housing (casting) onto which surface the braking surface may be machined. The respective braking surface may also be formed by adding additional elements, such as specific brake rings made of the suitable brake material having a specific roughness and stability.

[0050] According to a further exemplary embodiment the braking surface at the rotatable bearing ring and a corresponding brake pad surface of the brake pad comprises a normal being orthogonal to the rotating axis . Alternatively, the braking surface at the rotatable bearing ring and a corresponding brake pad surface of the brake pad comprise a normal being parallel to the rotating axis .

[0051] Hence, a specific orientation of the braking surfaces in relation to the rotating axis of the generator and hence a direction of transferring the braking force between the rotor and the stator can be adjusted. By specifying the orientation of the normal to these surfaces, the implementation delineates how the braking force is applied either perpendicularly or parallelly to the rotating axis .

[0052] The orthogonal orientation implies that the braking force is applied in a direction perpendicular to the axis of rotation. Hence, the brake pad may be pressed from a radially inner side in the direction to a radially outer side against the part of the rotatable bearing ring ( for example a part of the bearing housing or a raceway) . Thus, a lateral displacement between the rotor and the stator caused by the applied braking force may be reduced.

[0053] On the other hand, the parallel orientation of the normal implies that the braking force is applied along the rotating axis . Hence, the brake pad may be pressed along the axial direction against the braking surface . Thereby, the risk of ovalization of the rotating bearing ring due to the braking2024PF00559

[0054] 10

[0055] force is reduced, since the braking force is directed along the rotating axis .

[0056] According to a further exemplary embodiment the holding brake system is mounted to a drive end of the rotor, at which the hub of a wind turbine is coupleable to the rotor .

[0057] Alternatively, the holding brake system is mounted to a nondrive end of the rotor, wherein the non-drive end of the rotor is formed at an axial opposed end of the stator with respect to the drive end.

[0058] By mounting the holding brake system (in particular the brake pad and the brake section) to the front drive end of the generator, the distance between the load input (torque from wind force acting on the blades, weight force of the blades and the hub) and the brake point (at the contact section between the braking patent and the brake section) is reduced. This reduction results in less material need under load when braking results in reduced strength requirements for these materials .

[0059] However, in an exemplary embodiment it can also be beneficial to arrange the brake system or a further holding brake system at the non-drive end of the generator . The non-drive end of the generator denotes the axial end of the generator closest to the wind turbine tower .

[0060] According to a further exemplary embodiment, the holding brake system comprises an actuator, in particular an electrically, hydraulically or pneumatically driven actuator, for moving the brake pad with respect to the brake section.

[0061] By the present invention, an active holding brake system is described, wherein for example a control unit controls the actuator and hence the position and the braking force, respectively of the brake pad with respect to the braking surface of the brake section. The control of the actuator enhances the functionality of the holding brake system by2024PF00559

[0062] 11

[0063] providing a controlled and potentially automated means of engaging and disengaging the brake pad. This can lead to improved safety and reliability, as the actuator can be designed to respond to specific control inputs or environmental conditions, ensuring that the braking force is applied consistently and effectively. Furthermore, the use of an actuator can facilitate remote operation and monitoring of the brake system, which is particularly advantageous in wind turbine applications where accessibility can be challenging. By integrating an actuator, the generator ' s holding brake system can achieve a higher level of precision in its braking operations, potentially reducing wear and tear on the brake components and extending their service life .

[0064] The actuators may be mounted to either a mounting point in the fixed stator shaft or the casting of the fixed stator shaft or are mounted on the (drive end) stator plate . For the bearing device, especially for a fluid film bearing device, the forces may be taken by axial pads being pressed against the braking surface along the axial direction. Hence, weight loads may be reduced on the bearing' s axial pads specifically at low wind or vendor interventions and parking position. In an exemplary embodiment, a control unit may control the actuators individually and independent from each other so that a decided brake force around the circumference of the rotating axis may be adjusted.

[0065] According to a further exemplary embodiment, the holding brake system comprises a plurality of brake pads being arranged spaced apart from each other on the stator . The brake pads are arranged circumferentially above and below the rotating axis .

[0066] Alternatively, the brake pads are arranged below the rotating axis for absorbing a torque induced by the weight force of the rotor . Hence, the generator is free of any brake pads above the rotating axis .2024PF00559

[0067] 12

[0068] The term "below" denotes that the brake pads are arranged under or below a horizontal plane in which the rotating axis is arranged. Specifically, the brake pads are arranged with respect to the rotor in the lower half of the rotor disk or the rotating or stationary bearing ring, for example .

[0069] Specifically, the term below denotes that in a cross-sectional plane of the rotor, in which the rotating axis forms a center point, the brake pads are arranged vertically below the center point of the rotating axis .

[0070] The term "above" denotes that brake pads are arranged above the horizontal plane in which the rotating axis is arranged. Specifically, the brake pads are arranged with respect to the rotor in the lower half of the rotor disk or the rotating or stationary bearing ring, for example .

[0071] If the brake pads are arranged below the braking axis, braking from one side on the rotor (e . g. the rotor disk or rotor house part) by the brake pads creates a large braking force and hence a braking torque in the upwind direction and against the weight force and weight torque direction. Some of this braking force is then counteracted by gravity load (weight force and respective weight torque) from the blades and the hub, respectively, and the remaining force is counteracted by the bearing device . Hence, arranging the brake pads below the rotating axis, load on the structure may be reduced since the braking torque acts against the torque induced by the weight force . By positioning the brake pads below the rotating axis, the system can provide a more efficient braking force that directly addresses the torque induced by the rotor ' s weight, thereby enhancing the overall stability and safety of the wind turbine when it is in a nonrotating parking position.

[0072] According to a further exemplary embodiment, the holding brake system is a passive brake system, wherein the braking2024PF00559

[0073] 13

[0074] surface and the brake pad are arranged with respect to each other in such a manner, that

[0075] a) in an operating position (when the rotor rotates around the rotating axis) of the wind turbine, a gap exists between the braking surface and the brake pad and

[0076] b) in a parking position (if no or only a very slow rotation of the rotor around the stator exists) of the wind turbine, a frictional contact is provided between the braking surface and the brake pad.

[0077] The brake pad is in particular arranged in a region below the rotating axis, so that due to weight forces of the hub and the rotor, a frictional contact is enhanced between the braking surface and the brake pad and for absorbing a weight torque induced by the weight force of the rotor .

[0078] Specifically, in an exemplary embodiment, the holding brake system is free of brake pads above the rotating axis .

[0079] In the parking position of the wind turbine, a frictional contact is established between the braking surface and the brake pad, enabling the generation of a braking force to hold the rotor in a non-rotating parking position and in operating position (when the rotor rotates around the rotating axis) of the wind turbine, a gap exists between the braking surface and the brake pad. This arrangement ensures that the braking mechanism is only engaged when necessary, i . e . if a parking position should be adjusted. It is not necessary to provide active controlled brake pads that are controlled for example by the above-described actuator . However, in an exemplary embodiment, both, the above-described passive brake pads that are not controlled by any actuators and active brake pads that are controlled by the actuator .

[0080] Due to the huge load caused by weight and wind forces acting on the wind turbine parts, in particular the generator, the hub and the blades, a slight deformation of the wind turbine structure and in particular of the generator parts exists .2024PF00559

[0081] 14

[0082] For example, the gaps between the rotor and the stator in axial direction and as well between the rotor and the stator in radial direction vary between the operating position and the parking position of the wind turbine . Hence, this varying gaps can be used by the above-described passive brake system. Specifically, a torque is calculated by considering the force by the distance to the reference point . In the generator, the reference point of a torque can be defined at the bearing devices at the drive end and the bearing device at the opposed non drive end. The weight force of the hub and the blades as well as the rotor weight causes a weight moment reducing the distance between the brake pad at the stator and the braking surface at the rotor, if the respective brake pad and braking surface is arranged below the rotating axis . If the wind turbine is operating, the wind force acting on the blade causes lift and hence a lift torque that has a direction opposite to the weight torque . Hence, in operating position, the gap between the brake pad at the stator and the braking surface at the rotor can be provided, if the respective brake pad and braking surface are arranged below the rotating axis . Considering this, the approach of the present exemplary embodiment, the brake pad and the brake section can be formed and adjusted, such that in a parking position of the wind turbine a frictional contact between the brake pad and the braking surface exists and hence a passive brake function is established.

[0083] On the other side, if the wind turbine is in operating position, the generated lift torque acts against the weight torque so that structural deformation of the generator structure occurs, and the gap is provided so that no unintentional braking forces are generated.

[0084] This exemplary embodiment may simplify the overall brake system, reducing the complexity and potential points of failure associated with active brake systems that require actuators or other mechanical interventions .2024PF00559

[0085] 15

[0086] In a further embodiment, the brake pad is arranged in a region below the rotating axis for absorbing a torque induced by the weight force of the rotor according to the first aspect, the brake pad is arranged in a region below the rotating axis for absorbing a torque induced by the weight force of the rotor, the braking surface and the brake pad are arranged in such a manner with respect to each other, that, due to wind forces acting at the hub and the blade, in operating position of the wind turbine, a gap exists between the braking surface and the brake pad and in parking position of the wind turbine, due to weight forces of the hub and the rotor, a frictional contact is provided between the braking surface and the brake pad, the method further comprises controlling a pitch angle of the blade in such a manner, that lift generated by the blade is reduced if the blade is located above the rotating axis, or lift generated by the blade is increased if the blade is located below the rotating axis for generating a braking torque by the wind force acting on the blade, so that the braking torque enhances the weight torque induced by the weight force of the rotor .

[0087] In the following, exemplary embodiments of the method are described. According to an exemplary embodiment the method controls a wind turbine as described above, wherein the brake pad is arranged in a region below the rotating axis for absorbing a torque induced by the weight force of the rotor . The braking surface and the brake pad are arranged in such a manner with respect to each other, that, due to wind forces acting at the hub and the blade, in operating position of the wind turbine, a gap exists between the braking surface and the brake pad and in parking position of the wind turbine, due to weight forces of the hub and the rotor, a frictional contact is provided between the braking surface and the brake pad .

[0088] Considering this design of the generator, an exemplary embodiment of the method describing an adjustment of the parking brake position is provided. According to the method,2024PF00559

[0089] 16

[0090] a pitch angle of the blade can be controlled in such a manner, that lift generated by the blade is reduced if the blade is located above the rotating axis, or lift generated by the blade is increased if the blade is located below the rotating axis for generating a braking torque by the wind force acting on the blade, so that the braking torque enhances the weight torque induced by the weight force of the rotor .

[0091] Typically, a hub comprises two, preferably three, blades that are arranged spaced apart from each other in circumferential direction. Each blade comprises a pitch angle which defines the rotational position of the blade around its longitudinal axis (the longitudinal axis extends between the blade tip and the blade root which is coupled to the hub) . By adjusting the pitch angle, the leading edge of the blade can be adjusted with respect to the direction of the wind. Hence, by adjusting the pitch angle, the wind force acting on the blade and hence the lift force generated by the blade can be adj usted .

[0092] Hence, in parking position, where no rotation of the hub around the rotating axis takes place, the blade that extending from the rotating axis and the hub, respectively, along a vertical direction above the rotating axis, the pitch angle is adjusted in such a way that no or a reduced lift is generated, so that no reduction of the weight torque and the braking torque is caused, respectively.

[0093] Accordingly, if the pitch angle of the blade below the rotating axis is adjusted such that the lift generation is increased, the generated lifting torque acts in the same direction as the weight torque . Thereby, the lifting torque enhances the weight torque induced by the weight force of the rotor, so that the overall larger braking torque and braking force, respectively, can be generated.2024PF00559

[0094] 17

[0095] Summarizing, the lift is reduced if the blade is above the rotating axis and increased if the blade is below the rotating axis . This adjustment in lift generates a braking torque from the wind force acting on the blade, which enhances the weight torque induced by the rotor ' s weight force . Hence, when forces can be effectively utilized for increasing the braking force and thus enhances the stability and control of the wind turbine, particularly in its parking position. The exemplary embodiment of the method leverages the natural forces acting on the wind turbine components to create a reliable and efficient brake system, reducing the need for additional mechanical or electrical brake systems . The communication between components, such as the rotor, stator, brake pad, braking surface, hub, and blade, is orchestrated to optimize the braking force through strategic positioning and pitch angle control, thereby improving the overall performance and safety of the wind turbine .

[0096] Considering the above-mentioned design of the generator, wherein the brake pad is arranged below the rotating axis, an exemplary embodiment of the method describing an adjustment of an operating position and an initial start procedure of the wind turbine is provided. According to the method, a pitch angle of the blade can be controlled in such a manner, that lift generated by the blade is increased if the blade is located above the rotating axis, or lift generated by the blade is reduced if the blade is located below the rotating axis, such that the lift torque counteracts the weight torque induced by the weight force of the rotor .

[0097] The described control of the pitch angle ensures that, during a startup phase of the wind turbine for leaving the parking brake position to the operating position, the gap between the brake pads and the respective break surfaces is generated. When the wind turbine is in a parking position, the weight forces of the hub and rotor generate a frictional contact between the braking surface and the brake pad, thereby securing the rotor in place . The blade positioned above the2024PF00559

[0098] 18

[0099] rotating axis, the pitch angle is controlled such that the lift generated is increased, whereas it is reduced for the blade arranged below the rotating axis . This control of the blade ' s pitch angle is instrumental in generating a lift torque that counteracts the weight torque induced by the rotor ' s weight force . By doing so, the method effectively balances the forces acting on the rotor specifically in the startup phase of the wind turbine . Hence, a braking force can be controlled by the described passive holding brake system without the need of additional active actuators for controlling the brake pads .

[0100] It has to be noted that embodiments of the invention have been described with reference to different subj ect matters . In particular, some embodiments have been described with reference to apparatus type claims whereas other embodiments have been described with reference to method type claims . However, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subj ect matter also any combination between features relating to different subj ect matters, in particular between features of the apparatus type claims and features of the method type claims is considered as to be disclosed with this application.

[0101] The aspects defined above and further aspects of the present invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment . The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.

[0102] Independent of the grammatical term usage, individuals with male, female or other gender identities are included within the term.2024PF00559

[0103] 19

[0104] Brief Description of the Drawings

[0105] Fig. 1 shows a schematic view of an embodiment of a wind turbine generator with a rotor, stator, and holding brake system comprising brake pads above and below the rotating axisaccording to an exemplary embodiment of the present invention .

[0106] Fig. 2 shows a detailed view of the embodiment shown in Fig.

[0107] 1, showing brake section and brake pad arrangement in the generator in more detail .

[0108] Fig. 3 shows a schematic view of an embodiment of a wind turbine generator with a rotor, stator, and a passive holding brake system comprising brake pads below the rotating axis according to an exemplary embodiment of the present invention .

[0109] Fig. 4 shows a detailed view of the embodiment shown in Fig.

[0110] 3, showing brake section and brake pad arrangement in the generator in more detail .

[0111] Fig. 5 shows a schematic view of an embodiment of a wind turbine generator with a passive holding brake system comprising brake pads below the rotating axis and at the nondrive end according to an exemplary embodiment of the present invention .

[0112] Fig. 6 shows a schematic view of an embodiment of a wind turbine generator with a rotor, stator, and holding brake system comprising brake pads above and below the rotating axis at a bearing device according to an exemplary embodiment of the present invention.

[0113] Fig. 7 shows a detailed view of the embodiment shown in Fig.

[0114] 6, showing the bearing device, the brake section and the brake pad arrangement in the generator in more detail .2024PF00559

[0115] 20

[0116] Fig. 8 shows a schematic view of an embodiment of a wind turbine generator with a holding brake system comprising brake pads arranged at a stator plate above and below the rotating axis at a bearing device according to an exemplary embodiment of the present invention.

[0117] Fig. 9 shows a detailed view of the embodiment shown in Fig.

[0118] 8, showing the bearing device, the brake section and the brake pad arrangement in the generator in more detail .

[0119] Detailed Description

[0120] The illustrations in the drawings are schematic . It is noted that in different figures, similar or identical elements are provided with the same reference signs .

[0121] Fig. 1 shows a generator 100 for a wind turbine 150. The generator 100 comprises a rotor 110 and a stator 120. The rotor 110 includes a drive end 101 to which a hub 151 of the wind turbine 150 is coupled. The stator 120 supports the rotor 110, allowing it to rotate around a rotating axis 107. The generator 100 also features a holding brake system 130, which is mounted to both the rotor 110 and the stator 120. The holding brake system 130 includes a brake section 131 and at least one brake pad 132, in the shown example two or more brake bads above and below the rotating axis 107. The brake section 131 has a braking surface 201 (see Fig. 2 ) onto which the brake pad 132 can be pressed to generate a braking force by friction, thereby holding the rotor 110 in a non-rotating parking position.

[0122] The rotor 110 is rotatably mounted to the stator 120 via a bearing device 103. The bearing device 103 comprises a stationary bearing ring 104 mounted to the stator 120 and a rotatable bearing ring 105 mounted to the rotor 110. The brake section 131 is provided at the rotatable bearing ring 105 of the bearing device 103. The brake pad 132 is arranged2024PF00559

[0123] 21

[0124] at the stationary bearing ring 104.

[0125] The holding brake system 130 is mounted at the drive end 101 of the rotor 110. The rotor 110 has also a non-drive end 102, which is formed at an axial opposed end of the stator 120 with respect to the drive end 101. The holding brake system 130 includes an actuator 133 for moving the brake pad 132 with respect to the brake section 131. The actuator 133 can be electrically, hydraulically, or pneumatically driven.

[0126] The generator 100 further includes a plurality of brake pads 132 arranged circumferentially around the rotating axis 107. The brake pads 132 are positioned to be pressed against the braking surface 201 to apply a braking force to the brake section 131 and hence the rotor 110. The braking surface 201 and the brake pad 132 are arranged and adjusted such that, in the operating position of the wind turbine 150, a gap 106 exists between them. In the parking position of the wind turbine 150, a frictional contact is provided between the braking surface 201 and the brake pad 132, enhancing the frictional contact .

[0127] Fig. 2 illustrates a detailed view of the holding brake system 130 as shown in Fig. 1. The brake section 131 is shown mounted to the rotatable bearing ring 105, while the brake pad 132 is arranged at the stationary bearing ring 104. The actuator 133 is positioned to move the brake pad 132 towards the braking surface 201 of the brake section 131. The gap 106 between the braking surface 201 and the brake pad 132 is clearly depicted, emphasizing the frictional contact in the parking position.

[0128] The stator 120 includes a stator shaft 121 and a stator plate 122. The brake pad 132 can be arranged either at the casting of the fixed shaft of the stator 120 or at the stator plate 122. The braking surface 201 at the rotatable bearing ring 105 and the corresponding brake pad surface of the brake pad 132 have a normal na that comprises an angle a to the axial2024PF00559

[0129] 22

[0130] direction of the rotating axis 107 between 1 degree to 45 degrees .

[0131] The wind turbine 150 comprises a hub 151 to which at least one blade 152 for generating lift is coupled. The generator 100, with its rotor 110 and stator 120, is integrated into the wind turbine 150. The holding brake system 130, with its brake section 131 and brake pad 132, ensures that the rotor 110 can be held in a non-rotatable parking position, providing stability and safety to the wind turbine 150.

[0132] The holding brake system 130 is designed to keep the rotor 110 stationary when the wind turbine 150 is not in operation, for example during low wind or during maintenance operations . Specifically, the holding brake system 130 is designed as a single sided holding brake system. Hence, the brake section 131 has one, in particular only one, side with a braking surface 201, onto which the brake pad 132 is pressed to create the necessary frictional force for holding the rotor 110 in a non-rotating parking position. Hence, the braking force that is generated by pressing the pad 132 directly onto the braking surface 201 is directly transferred into the structure of the rotor 110. The brake section 131 is formed on a structural part of the rotor 110, such as a rotor disk 111 running in circumferential direction all around the rotating axislOV .

[0133] The brake pad 132 is a component of the holding brake system that is pressable, actively by an actuator as shown in Fig. 2 or passively by movement of the rotor and stator structure as shown in Fig. 3 to 5, onto the braking surface 201 of the brake section 131. When pressed against the braking surface 201, the brake pad 132 generates a braking force through friction, which is used to hold the rotor 110 in a stationary position .2024PF00559

[0134] 23

[0135] Fig. 3 shows a further exemplary embodiment a generator 100 for a wind turbine 150. The generator 100 comprises a rotor 110 and a stator 120. The rotor 110 includes a drive end side 101 to which a hub 151 having blades 152 is coupled. The stator 120 is configured such that the rotor 110 is rotatably mounted around a rotating axis 107. The rotor 110 is shown with a rotor disk 111 and the stator 120 comprises the stator plate 122 .

[0136] The holding brake system 130 is mounted to both the rotor 110 and the stator 120. The holding brake system 130 comprises a brake section 131 and a brake pad 132. The brake section 131 has a braking surface 201 onto which the brake pad 132 is pressable to generate a braking force by friction, thereby holding the rotor 110 in a non-rotating parking position. The brake section 131 is provided at a movable rotor structure of the rotor 110, while the brake pad 132 is arranged at a stationary stator structure of the stator 120.

[0137] The generator 100 further includes a bearing device 103 for supporting the rotor 110 rotatably relative to the stator 120. The bearing device 103 comprises a stationary bearing ring 104 mounted to the stator 120 and a rotatable bearing ring 105 mounted to the rotor 110. The brake section 131 is provided at the rotatable bearing ring 105 of the bearing device 103.

[0138] Fig. 4 provides a more detailed view of the interaction between the rotor 110 and the stator 120, specifically highlighting the holding brake system 130. The brake section 131 is shown mounted on the rotatable bearing ring 105, and the brake pad 132 is positioned on the stationary bearing ring 104. The braking surface 201 and the brake pad 132 are arranged such that in the operating position of the wind turbine 150, a gap 106 exists between them. In the parking position, frictional contact is provided between the braking surface 201 and the brake pad 132 due to the weight forces FW2024PF00559

[0139] 24

[0140] of the hub 151 and the rotor 110, enhancing the braking force . Specifically, the rotating axis 107 of the generator 100 may be slightly inclined with respect to a horizontal axis, so that the lift generated by blades 152 of the wind turbine 150 has a vertical direction component which may be beneficial for the structure of the wind turbine 150 during operation. Hence, in operating position of the wind turbine 150, the blades 152 generate lift torque ML which acts in clockwise direction in the arrangement of the wind turbine 150 shown in Fig. 3. On the other side, weight force generated by the weight of the hub 151, the blades 152 and the rotor 110 generate a weight force Fw that generates a weight torque MW which acts in counterclockwise direction in the arrangement of the wind turbine 150 shown in Fig. 3. The weight torque MW is absorbed by the holding brake system 130 when the wind turbine 150 is in the parking position.

[0141] Specifically, the brake pads 132 are arranged below the rotating axis 107 to absorb the weight torque MW induced by the weight force FW.

[0142] The braking surface 201 and the brake pads 132 are arranged in such a manner with respect to each other, that, due to wind forces acting at the hub 151 and the blades 152 in operating position of the wind turbine 150, a gap 106 exists between the braking surface 201 and the brake pads 132 and in parking position of the wind turbine, due to the weight torque MW, a frictional contact is provided between the braking surface 201 and the brake pads 132. Hence, the holding brake system may be free of brake pads above the rotating axis 107 and free of any actuator 133 for moving the brake pads 132. It is not necessary to provide active controlled brake pads 132 that are controlled for example by the above-described actuator 133.

[0143] Due to the load caused by weight and wind forces acting on the wind turbine parts, in particular the generator 100, the hub 151 and the blades 152, a slight deformation of the wind turbine structure and in particular of the generator parts2024PF00559

[0144] 25

[0145] exists . Hence, the varying gap size of the gap 106 between the brake pads 132 and the brake section 131 is used by the passive brake system 130. The weight force causes the weight torque MW to reduce the distance between the brake pad 132 and the braking surface 201, if the respective brake pad 132 and braking surface 201 are arranged below the rotating axis 107. If the wind turbine 150 is operating, the wind force acting on the blade 152 causes lift and hence a lift torque ML that has a direction opposite to the weight torque MW. Hence, in operating position, the gap 106 between the brake pad 132 and the braking surface 201 can be provided, so that no unintentional braking forces are generated.

[0146] By the shown passive holding brake system 130 it is possible to provide a break control by controlling, a pitch angle of the blade 152 in such a manner, that lift generated by the blade 152 is reduced if the blade is located above the rotating axis 107, or lift generated by the blade 152 is increased if the blade 152 is located below the rotating axis 107 for generating a stronger braking torque by the wind force acting on the blades 152, so that the braking torque enhances the weight torque MW induced by the weight force FW.

[0147] As shown in Fig. 3, blades 152 are arranged spaced apart from each other in circumferential direction. Each blade 152 comprises a pitch angle which defines the rotational position of the blade 152 around its longitudinal axis . By adjusting the pitch angle, the leading edge of the blade 152 can be adjusted with respect to the direction of the wind. Hence, by adjusting the pitch angle, the wind force acting on the blade 152 and hence the lift force generated by the blade 152 can be adjusted.

[0148] Hence, in parking position, where no rotation of the hub 151 around the rotating axis 107 takes place, the blade 152 that extending from the rotating axis 107 and the hub 151, respectively, along a vertical direction above the rotating axis 107, the pitch angle is adjusted in such a way that no2024PF00559

[0149] 26

[0150] or a reduced lift is generated, so that no reduction of the weight torque and the braking torque is caused. Accordingly, in parking position, the pitch angle of the blade 152 below the rotating axis 107 can be adjusted such that the lift generation is increased, so that the generated lifting torque ML acts in the same direction as the braking torque and the weight torque MW. Thereby, the lifting torque ML enhances the weight torque MW induced by the weight force, so that the overall larger braking torque and braking force, respectively, is generated.

[0151] However, in a startup phase of the operation of the wind turbine, for leaving the parking brake position to the operating position, the gap 106 between the brake pads 132 and the respective break surfaces 201 is generated, if the respective pitch angles of the blades 152 are adjusted in such a way that the blades 152 extending above the rotating axislOV generate more lift than the blades 152 extending below the rotating axislOV .

[0152] Fig. 5 shows an embodiment of a generator 100 for a wind turbine 150 having a passive holding brake system 130 similar to the embodiment illustrated in Fig. 3. However, in the embodiment shown in Fig, 5. The holding brake system 130 is arranged at the non-drive end 102 of the generator 100.

[0153] The holding brake system 130 is mounted to both the rotor 110 and the stator 120. This system includes a brake section 131 and a brake pad 132. The brake section 131 is shown to have a braking surface 201 onto which the brake pad 132 is pressable for generating a braking force by friction to hold the rotor 110 in a non-rotating parking position. The brake section 131 is provided at a movable rotor structure of the rotor 110, while the brake pad 132 is arranged at a stationary stator structure of the stator 120.

[0154] The figure also illustrates a bearing device 103 at the drive2024PF00559

[0155] 27

[0156] end 101 for supporting the rotor 110 rotatably to the stator 120 .

[0157] The holding brake system 130 is mounted at the non-drive end 102 of the rotor 110, which is formed at an axial opposed end with respect to the drive end 101 at which the bearing device 103 is arranged. The brake pad 132 is arranged at the stationary structure of the stator 120, such as a shaft section of the shaft 121 or a stator plate 122 of the stator 120 at the non-drive end 102. Furthermore, the stator 120 may comprise structural elements, such as supporting frames, that are coupled for example to the tower 153 or the bedframe 154, which couples the generator 100 to the tower 153.

[0158] The brake section 131 may be formed at a lateral surface (normal parallel to rotating axis 107 ) of the rotor housing of the rotor 110 at the non-drive end 102.

[0159] The brake pad 132 and the brake section 131 are arranged in a region below the rotating axis 107 for absorbing a torque induced by the weight force FW of the rotor 110 and for providing a frictional brake force in parking position of the wind turbine 150.

[0160] Fig. 6 shows a schematic view of an embodiment of a wind turbine generator 100 with a rotor 110, stator 120, and s holding brake system 130 comprising brake pads 132 above and below the rotating axislOV at a bearing device 103 according to an exemplary embodiment of the present invention. Fig. 7 shows a detailed view of the embodiment shown in Fig. 6, showing the bearing device 103, the brake section 131 and the brake pad 132 arrangement in the generator 100 in more detail .

[0161] The generator 100 comprises the rotor 110 and the stator 120, with the rotor 110 being rotatably mounted around a rotating axis 107. The rotor 110 comprises a drive end side to which a2024PF00559

[0162] 28

[0163] hub 151 of the wind turbine 150 is coupleable . The hub 151 is connected to at least one blade 152 for generating lift .

[0164] The stator 120 comprises a stator shaft 121 and a stator plate 122. The rotor 110 is supported by the bearing device 103, which comprises a stationary bearing ring 104 mounted to the stator 120, in particular to the shaft 121 of the stator 120, and a rotatable bearing ring 105 mounted to the rotor 110, in particular to the rotor disk 111 of the rotor 110. The bearing device 103 supports the rotor 110 rotatably to the stator 120.

[0165] The holding brake system 130 is mounted to both the rotor 110 and the stator 120. The holding brake system 130 comprises a brake section 131 and a brake pad 132. The brake section 131 is provided at the rotatable bearing ring 105 of the bearing device 103, and the brake pad 132 is arranged at the stationary bearing ring 104. The brake section 131 features a braking surface 201 onto which the brake pad 132 is pressable to generate a braking force by friction, thereby holding the rotor 110 in a non-rotating parking position.

[0166] The stationary bearing ring 104, being affixed to the stator 120, provides a stable base, while the rotatable bearing ring 105, attached to the rotor 110, allows for the necessary rotational freedom. The rotatable bearing ring 105 is mounted to an inner opening of the rotor disk 111 so that forces introduced into the rotor 110 by the wind force acting on the blades 152 and also weight forces of the hub 151 and the rotor housing are forwarded via the rotatable bearing ring 105 to the stationary bearing ring 104 and further to the structural parts of the stator 120. From the stator 120, the forces are further transferred to other parts of the wind turbine 150, such as the bedframe 154 at the tower 153 of the wind turbine 150.

[0167] As shown, the brake pad 132 is arranged at the stationary bearing ring 104. Alternatively, the brake pad 132 may be2024PF00559

[0168] 29

[0169] arranged either at a casting of the fixed shaft 121 of the or a stator plate 122 of the stator (as shown in Fig. 8 and Fig . 9 ) .

[0170] An actuator 133 of the brake pad 132 may be placed inside of the fixed stationary shaft 121 and is pushing the brake pad 132 outwards onto the movable rotatable bearing ring 105 (e . g. a respective raceway of the bearing) . Hence, the brake pads 132 push from the radially inner side onto the radially outer surface (or side surface) of the rotatable bearing ring 105 mounted to the rotor 110.

[0171] In the shown example, the braking surface 201 at the rotatable bearing ring 105 and a corresponding brake pad surface of the brake pad 132 comprises a normal nb being orthogonal to the rotating axis 107. Alternatively, the braking surface 201 at the rotatable bearing ring 105 and a corresponding brake pad surface of the brake pad 132 comprise a normal being parallel to the rotating axis 107. The orthogonal orientation implies that the braking force is applied in a direction perpendicular to the axis of rotation and the rotating axis 107, respectively. Hence, the brake pad 132 may be pressed from a radially inner side in the direction to a radially outer side against the part of the rotatable bearing ring 105 ( for example a part of the bearing housing or a raceway) .

[0172] Fig. 8 shows a schematic view of an embodiment of a wind turbine generator 100 with a holding brake system 130 comprising brake pads 132 arranged at a stator plate 122 above and below the rotating axisl07 at a bearing device 103 according to an exemplary embodiment of the present invention. Fig. 9 shows a detailed view of the embodiment shown in Fig. 8, showing the bearing device 103, the brake section 131 and the brake pad arrangement in the generator 100 in more detail .2024PF00559

[0173] 30

[0174] In contrast to the embodiment shown in Fig. 6, the brake pads 132 (and e . g. its actuators 133) are mounted on the stator plate 122. Hence, the brake pads 132 push from the radially outer side onto the radially outer surface (or side surface) of the rotatable bearing ring 105 mounted to the rotor 110 or to the additional rotor braking part 901. The rotatable bearing ring 105 comprises a respective radially outer surface, where a braking surface 201 is machined onto the bearing ring surface . In the shown exemplary embodiment, the respective braking surface is formed by adding the additional rotor braking part 901, extending from the rotor bearing housing axially inside the generator 100. The additional rotor braking part 901 may form a brake ring attached to the rotor bearing housing.

[0175] It should be noted that the term "comprising" does not exclude other elements or steps and "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims .

Claims

2024PF0055931CLAIMS :1 . Generator ( 100 ) for a wind turbine ( 150 ) , the generator ( 100 ) comprisinga rotor ( 110 ) comprising a drive end side to which a hub ( 151 ) of a wind turbine ( 150 ) is coupleable ,a stator ( 120 ) to which the rotor ( 110 ) is rotatably mounted around a rotating axis ( 107 ) ,a holding brake system ( 130 ) mounted to the rotor ( 110 ) and the stator ( 120 ) ,wherein the holding brake system ( 130 ) comprising a brake section ( 131 ) and a brake pad ( 132 ) ,wherein the brake section ( 131 ) comprises one braking side having a braking surface ( 201 ) onto which the brake pad ( 132 ) is pressable for generating a braking force by friction to hold the rotor ( 110 ) in a non-rotating parking position .2 . Generator ( 100 ) according to claim 1 ,wherein the brake section ( 131 ) is provided at a movable rotor structure of the rotor ( 110 ) and the brake pad ( 132 ) is arranged at a stationary stator structure of the stator ( 120 ) .3 . Generator ( 100 ) according to claim 2 ,wherein the movable rotor structure comprises a rotor disk being rotatable around the rotating axis ( 107 ) .4 . Generator ( 100 ) according to claim 2 or 3 ,wherein the braking surface ( 201 ) comprises a normal comprising an axial direction component of the rotating axis ( 107 ) ,wherein the normal is parallel to the axial direction, or the normal comprises an angel to the axial direction between 1 ° to 45 ° .5 . Generator ( 100 ) according to one of the claims 1 to 4 , further comprising2024PF0055932a bearing device ( 103 ) for supporting the rotor ( 110 ) rotatably to the stator ( 120 ) ,wherein the bearing device ( 103 ) comprises a stationary bearing ring ( 104 ) being mounted to the stator ( 120 ) , in particular a stator shaft , and a rotatable bearing ring ( 105 ) being mounted to the rotor ( 110 ) ,wherein the brake section ( 131 ) is provided at the rotatable bearing ring ( 105 ) of the bearing device ( 103 ) ,wherein the bearing device ( 103 ) is in particular a rolling bearing, a plain bearing or a fluid film bearing .6 . Generator ( 100 ) according to one of the claims 5 , wherein the brake pad ( 132 ) is arranged at the stationary bearing ring ( 104 ) , orwherein the brake pad ( 132 ) is arranged either at a casting of the fixed shaft of the stator ( 120 ) or a stator plate ( 122 ) of the stator ( 120 ) .7 . Generator ( 100 ) according to claim 5 or 6 ,wherein the braking surface ( 201 ) at the rotatable bearing ring ( 105 ) and a corresponding brake pad surface of the brake pad ( 132 ) comprises a normal being orthogonal to the rotating axis ( 107 ) , orwherein the braking surface ( 201 ) at the rotatable bearing ring ( 105 ) and a corresponding brake pad surface of the brake pad ( 132 ) comprises a normal being parallel to the rotating axis ( 107 ) .8 . Generator ( 100 ) according to one of the claims 1 to 7 , wherein the holding brake system ( 130 ) is mounted to a drive end ( 101 ) of the rotor ( 110 ) , at which the hub ( 151 ) of a wind turbine ( 150 ) is coupleable to the rotor ( 110 ) , or wherein the holding brake system ( 130 ) is mounted a non-drive end ( 102 ) of the rotor ( 110 ) , wherein the non-drive end ( 102 ) of the rotor ( 110 ) is formed at an axial opposed end of the stator ( 120 ) with respect to the drive end ( 101 ) .9 . Generator ( 100 ) according to one of the claims 1 to 8 ,2024PF0055933wherein the holding brake system ( 130 ) comprises an actuator ( 133 ) , in particular an electrically, hydraulically or pneumatically driven actuator ( 133 ) , for moving the brake pad ( 132 ) with respect to the brake section ( 131 ) .10 . Generator ( 100 ) according to claim 9 ,wherein the holding brake system ( 130 ) comprises a plurality of brake pads ( 132 ) being arranged spaced apart from each other on the stator ( 120 ) ,wherein the plurality of brake pads ( 132 ) are arranged circumferentially above and below the rotating axis ( 107 ) , or wherein the plurality of brake pads ( 132 ) is arranged below the rotating axis ( 107 ) for absorbing a torque induced by the weight force ( FW) of the rotor ( 110 ) .11 . Generator ( 100 ) according to one of the claims 1 to 10 , wherein the braking surface ( 201 ) and the brake pad ( 132 ) are arranged with respect to each other in such a manner, that in an operating position of the wind turbine ( 150 ) , a gap ( 106 ) exists between the braking surface ( 201 ) and the brake pad ( 132 ) andin parking position of the wind turbine ( 150 ) , a frictional contact is provided between the braking surface ( 201 ) and the brake pad ( 132 ) ,wherein the brake pad ( 132 ) is in particular arranged in a region below the rotating axis ( 107 ) , so that due to weight forces ( FW) of the hub ( 151 ) and the rotor ( 110 ) , a frictional contact is enhanced between the braking surface ( 201 ) and the brake pad ( 132 ) and for absorbing a weight torque (MW) induced by the weight force ( FW) of the rotor ( 110 ) .12 . Wind turbine ( 150 ) , comprisinga hub ( 151 ) to which at least a blade ( 152 ) for generating li ft is coupled,a generator ( 100 ) comprising a rotor ( 110 ) comprising a drive end side to which the hub ( 151 ) is coupled, a stator ( 120 ) to which the rotor ( 110 ) is rotatably mounted around a2024PF0055934rotating axis ( 107 ) , and a holding brake system ( 130 ) mounted to the rotor ( 110 ) and the stator ( 120 ) ,wherein the holding brake system ( 130 ) comprising a brake section ( 131 ) and a brake pad ( 132 ) ,wherein the brake section ( 131 ) comprises one braking side having a braking surface ( 201 ) onto which the brake pad ( 132 ) is pressable for generating a braking force by friction to hold the rotor ( 110 ) in a non-rotatable parking position .13 . Method of controlling a parking position of a wind turbine ( 150 ) according to claim 12 , the method comprising pressing the brake pad ( 132 ) onto the braking surface ( 201 ) of the braking side of the brake section ( 131 ) for generating a braking force by friction to hold the rotor ( 110 ) in a non-rotatable parking position .14 . Method according to claim 13 ,wherein the brake pad ( 132 ) is arranged in a region below the rotating axis ( 107 ) for absorbing a torque induced by the weight force ( FW) of the rotor ( 110 ) ,wherein the braking surface ( 201 ) and the brake pad ( 132 ) are arranged in such a manner with respect to each other, that , due to wind forces acting at the hub ( 151 ) and the blade ( 152 ) , in operating position of the wind turbine ( 150 ) , a gap ( 106 ) exists between the braking surface ( 201 ) and the brake pad ( 132 ) and in parking position of the wind turbine ( 150 ) , due to weight forces ( FW) of the hub ( 151 ) and the rotor ( 110 ) , a frictional contact is provided between the braking surface ( 201 ) and the brake pad ( 132 ) ,wherein the method further comprisescontrolling a pitch angle of the blade ( 152 ) in such a manner, thatli ft generated by the blade ( 152 ) is reduced i f the blade ( 152 ) is located above the rotating axis ( 107 ) , or li ft generated by the blade ( 152 ) is increased i f the blade ( 152 ) is located below the rotating axis ( 107 ) for generating a braking torque by the wind force acting on the blade ( 152 ) , so that the braking torque enhances the2024PF00559weight torque (MW) induced by the weight force ( FW) of the rotor ( 110 ) .15 . Method according to claim 13 or 14 ,wherein the brake pad ( 132 ) is arranged in a region below the rotating axis ( 107 ) for absorbing a weight torque (MW) induced by the weight force ( FW) of the rotor ( 110 ) , wherein the braking surface ( 201 ) and the brake pad ( 132 ) are arranged in such a manner with respect to each other, that , due to wind forces acting at the hub ( 151 ) and the blade ( 152 ) , in operating position of the wind turbine ( 150 ) , a gap ( 106 ) exists between the braking surface ( 201 ) and the brake pad ( 132 ) and in parking position of the wind turbine ( 150 ) , due to weight forces ( FW) of the hub ( 151 ) and the rotor ( 110 ) , a frictional contact is provided between the braking surface ( 201 ) and the brake pad ( 132 ) ,wherein the method further comprisescontrolling a pitch angle of the blade ( 152 ) in such a manner, thatli ft generated by the blade ( 152 ) is increased i f the blade ( 152 ) is located above the rotating axis ( 107 ) , orli ft generated by the blade ( 152 ) is reduced i f the blade ( 152 ) is located below the rotating axis ( 107 ) for generating a li ft torque (ML ) by the wind force acting on the blade ( 152 ) , so that the li ft torque (ML ) counteracts the weight torque (MW) induced by the weight force ( FW) of the rotor ( 110 ) .

Images