Stator assemblies and methods of providing the same

Abstract

To provide a stator assembly for an electrical machine.SOLUTION: The present disclosure relates to a stator assembly for an electrical machine. The stator assembly comprises a plurality of stator frames 110 forming a stator rim. The stator frames define ring sectors and are attached to each other to form a stator rim. Further, the stator frames at least partially form an air distribution channel extending from at least one of the stator frames into another of the stator frames. Methods for assembling the stator assembly are also disclosed.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a stator assembly and a method of providing a stator assembly.

Background Art

[0002] Currently, wind turbines are generally used to supply power to the power grid. This type of wind turbine generally includes a tower and a rotor disposed on the tower. The rotor typically includes a hub and a plurality of blades and is configured to rotate under the influence of wind on the blades. This rotation usually generates torque that is transmitted directly, "direct drive" or "gearless", or using a gearbox, via the rotor shaft to a generator. In this way, the generator generates electricity that can be supplied to the power grid.

[0003] Other electrical machines such as wind turbine generators and motors generally include a rotor and a stator. The rotor rotates relative to the stator. The rotor may be an internal structure and the stator may be another structure. Thus, the stator can surround the rotor. Alternatively, in other configurations, the arrangement may be reversed such that the rotor surrounds the stator.

[0004] Large generators such as modern wind turbines may be permanent magnet generators (PMGs) or electrically excited generators.

[0005] In a permanent magnet generator, generally, permanent magnets (PMs) are disposed on the rotor, while winding elements, i.e., coils, are usually included in the stator. Alternatively, the permanent magnets can be disposed within the stator structure and the winding elements can be disposed within the rotor structure. Permanent magnet generators are generally highly reliable and require less maintenance than other types of generators.

[0006] On the other hand, electrically excited generators generally include a rotor with multiple pole shoes and excitation windings, i.e., coils. When in use, current is applied to the excitation coils. The applied current forms the polarity of the magnetic poles, and adjacent poles have different magnetic polarities. As the rotor rotates, the magnetic field from the pole shoes is applied to the stator windings, creating a fluctuating magnetic flux in the stator windings and generating a voltage in the stator windings. In this way, in an excited generator, the magnetic field for generating power is electrically generated, so permanent magnets are not required.

[0007] Electromagnetic components of electromachines, such as motors or generators, can be cooled to reduce energy losses related to heat. To this end, cooling systems can be provided for the electromagnetic components of the rotor, i.e., permanent magnets and electric windings. Electromachines may include cooling inlets for distributing cooling fluid around these electromagnetic components. However, the internal geometry of the electromachine can hinder flow distribution, resulting in substantially non-uniform cooling. This can cause some electromagnetic components to operate at different temperatures than others, potentially reducing the overall efficiency of the electromachine.

[0008] Furthermore, there is a growing trend to create larger wind turbines, such as so-called "multi-megawatt" wind turbines, in order to capture more wind and convert wind energy into electricity. In particular, with direct-drive wind turbines, this can lead to generators of very large dimensions, for example, with an axial length of 3, 4, or 5 meters or more and a diameter of 6, 8, or 10 meters or more. This presents specific challenges in terms of the manufacture, assembly, transportation, and cooling of such large electrical machinery.

[0009] The types of electromachines and potential problems described herein are not limited to wind turbine generators. In fact, electromachines of considerable size, namely steam turbines and water turbines, can suffer from the same cooling and manufacturing problems or complexities.

[0010] Accordingly, this disclosure provides a method and system for overcoming some of the aforementioned challenges, at least partially. [Overview of the project] [Problems that the invention aims to solve]

[0011] In one aspect of the present disclosure, a stator assembly for an electromechanical device is provided. The stator assembly includes a plurality of stator frames defining a ring sector. The stator frames are mounted together to form a stator rim. The stator rim has circumferential sides configured to carry electromagnetically active stator elements. Furthermore, the circumferential sides face an air gap between the stator assembly and a rotor. Furthermore, the plurality of stator frames form at least partially an air distribution channel. The air distribution channel extends from at least one of the stator frames to another and distributes air along the circumferential direction of the stator rim. [Means for solving the problem]

[0012] According to this embodiment, the fact that the stator assembly includes two or more stator frames significantly reduces the weight and size per frame compared to a complete stator rim. This allows for the use of standard manufacturing techniques and further reduces the complexity of transportation and logistics from the manufacturing plant to the wind turbine site. This configuration also allows for the selective replacement of stator ring sectors in the event of failure, thereby reducing overall maintenance costs. Furthermore, the multiple stator frames form air distribution channels for circumferential air distribution, at least partially. This promotes more uniform cooling and, at the same time, allows for a reduction in cooling flow rate to achieve a given overall heat exchange. Thus, a less powerful cooling system can be used. Moreover, since the different stator frames of the formed stator rim are in internal fluid communication, the stator assembly allows for a more versatile configuration with existing cooling systems. That is, not all stator frames may require air inlets for effective heat exchange.

[0013] Here, a ring sector can be considered as a portion of a ring enclosed between two radii and one arc. Several ring sectors can be joined together to form a complete ring. In this disclosure, a stator rim can be formed as a ring, where a ring sector may be a portion of a circular sector. That is, in embodiments where the stator is a central structure and the rotor radially surrounds the stator, various stator frames can form a circular sector that includes ring sectors for forming the rim portion of the stator.

[0014] In another embodiment, a method for providing a stator assembly is provided. This method includes providing at least two stator frames defining a ring sector. Each stator frame at least partially forms an air distribution channel that distributes air circumferentially across the stator frame. Furthermore, the method includes providing at least two stator frames defining a ring sector, each stator frame at least partially forming an air distribution channel that distributes air circumferentially across the stator frame, and joining the stator frames at the radial end walls of the stator frames to form a stator rim, the radial end walls including an air distribution orifice.

[0015] According to this additional embodiment, the method enables the assembly of the stator rim by joining the stator frame. Thus, this method enables the manufacture of the stator frame that defines the ring sector, which is then used to form the stator assembly. This reduces the complexity of manufacturing, the logistics of space and transportation, and the requirements for lifts during transportation and storage.

[0016] Further objects, advantages, and features of the embodiments of this disclosure will become apparent to those skilled in the art by examining the specification or by practicing the invention. [Brief explanation of the drawing]

[0017] [Figure 1] A schematic perspective view of an example of a wind turbine is shown. [Figure 2] Examples of wind turbine hubs and nacelles are shown. [Figure 3] A schematic front-angle perspective view of an example of a stator assembly is shown. [Figure 4] A schematic rear perspective view of an example of the stator assembly shown in Figure 3 is provided. [Figure 5] A schematic detail view of one radial end wall of the exemplary stator frame shown in Figures 2 and 3 is provided. [Figure 6] Figures 3-5 show schematic detailed cross-sectional views of a generator assembly, including the stator assembly, according to the embodiment shown. [Figure 7] A flowchart illustrating an example of a method for providing a stator assembly is shown. [Modes for carrying out the invention]

[0018] Hereinafter, embodiments of the present disclosure are given in detail, with one or more examples shown in the drawings. Each embodiment is provided as a description of the invention, not as an limitation. Indeed, it will be apparent to those skilled in the art that various modifications and changes can be made without departing from the scope or spirit of the present disclosure. For example, features illustrated or described as part of one embodiment can be used in conjunction with another embodiment to obtain yet another embodiment. Thus, the present disclosure is intended to encompass modifications and variations that fall within the scope of the appended claims and their equivalents.

[0019] Figure 1 is a perspective view of an example of a wind turbine 10. In this example, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In this embodiment, the wind turbine 10 includes a tower 15 extending from a support system 14 on the ground 12, a nacelle 16 mounted on the tower 15, and a rotor 18 coupled to the nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to the hub and extending outward from the hub 20. In this example, the rotor 18 has three rotor blades 22. In another embodiment, the rotor 18 includes three or more or fewer rotor blades 22. The tower 15 may be made of tubular steel to define a cavity between the support system 14 and the nacelle 16. In an alternative embodiment, the tower 15 is any suitable type of tower having any suitable height. By another method, the tower may be a hybrid tower including a concrete portion and a tubular steel portion. Additionally, the tower can be a partial or full lattice tower.

[0020] The rotor blades 22 are spaced around the hub 20 and facilitate the rotation of the rotor 18, enabling the transfer of kinetic energy from the wind into usable mechanical energy and then into electrical energy. The rotor blades 22 are fitted to the hub 20 by coupling the blade root portion 24 to the hub 20 at a plurality of load transfer regions 26. The load transfer regions 26 can have a hub load transfer region and a blade load transfer region (neither shown in FIG. 1). The loads induced on the rotor blades 22 are transferred to the hub 20 via the load transfer regions 26.

[0021] In an embodiment, the rotor blades 22 can have a length ranging from about 15 meters (m) to about 90 meters or more. The rotor blades 22 can have any suitable length that enables the wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include lengths less than 20 m, 37 m, 48.7 m, 50.2 m, 52.2 m, or greater than 91 m. When wind hits the rotor blades 22 from the wind direction 28, the rotor 18 rotates about the rotor shaft 30. As the rotor blades 22 rotate and are subject to centrifugal force, the rotor blades 22 are also subject to various forces and moments. Thus, the rotor blades 22 can deflect and / or rotate from a neutral or non-deflected position to a deflected position.

[0022] Furthermore, the pitch angle of the rotor blades 22, i.e., the angle that determines the orientation of the rotor blades 22 with respect to the wind direction, can be changed by the pitch system 32 in order to control the loads and power generated by the wind turbine 10 by adjusting the angular position of at least one rotor blade 22 with respect to the wind vector. The pitch axis 34 of the rotor blades 22 is shown. During operation of the wind turbine 10, the pitch system 32 can specifically change the pitch angle of the rotor blades 22 such that the angle of attack of (a portion of) the rotor blades is reduced, facilitating a reduction in rotational speed and / or facilitating stall of the rotor 18.

[0023] In this example, the blade pitch of each rotor blade 22 is individually controlled by the wind turbine control device 36 or the pitch control system 80. Alternatively, the blade pitch of all the rotor blades 22 may be simultaneously controlled by this control system.

[0024] Furthermore, in this embodiment, as the wind direction 28 changes, the yaw direction of the nacelle 16 may rotate about the yaw axis 38 to position the rotor blades 22 with respect to the wind direction 28.

[0025] In the embodiment, the wind turbine control device 36 is shown as being concentrated within the nacelle 16, but the wind turbine control device 36 may be a distributed system throughout the entire wind turbine 10, on the support system 14, within a wind power plant, and / or at a remote control center. The wind turbine control device 36 includes a processor 40 configured to execute the methods and / or steps described herein. Further, many of the other components described herein include a processor.

[0026] It should be understood that the term "processor" as used herein is not limited to the integrated circuits referred to as computers in the art, but broadly means a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application-specific integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that the processor and / or the control system may also include a memory, an input channel, and / or an output channel.

[0027] Figure 2 is an enlarged cross-sectional view of a portion of the wind turbine 10. In this embodiment, the wind turbine 10 includes a nacelle 16 and a rotor 18 rotatably coupled to the nacelle 16. Specifically, the hub 20 of the rotor 18 is rotatably coupled to a generator 42 located within the nacelle 16 by a main shaft 44, a gearbox 46, a high-speed shaft 48, and a coupling 50. In this embodiment, the main shaft 44 is at least partially coaxial with the longitudinal axis (not shown) of the nacelle 16. The rotation of the main shaft 44 drives the gearbox, which in turn drives the high-speed shaft 48 by converting the relatively slow rotational motion of the rotor 18 and the main shaft 44 into the relatively fast rotational motion of the high-speed shaft 48. The latter is connected to the generator 42 to generate electrical energy with the help of the coupling 50. Furthermore, a transformer 90 and / or appropriate electronic equipment, switches and / or inverters can be placed within the nacelle 16 to convert the electrical energy generated by the generator 42, which has a voltage between 400V and 1000V, into electrical energy with a medium voltage (10-35kV). This electrical energy is then conducted from the nacelle 16 to the tower 15 via power cables.

[0028] The gearbox 46, generator 42, and transformer 90 may be supported by a main support structure frame of the nacelle 16, which optionally embodies as a main frame 52. The gearbox 46 may include a gearbox housing connected to the main frame 52 by one or more torque arms 103. In embodiments, the nacelle 16 also includes a main front support bearing 60 and a main rear support bearing 62. Furthermore, the generator 42 may be attached to the main frame 52 by decoupling support means 54 to prevent vibrations of the generator 42 from being introduced into the main frame 52 and becoming a source of noise emission.

[0029] Optionally, the main frame 52 is configured to transport the weight of the rotor 18 and the components of the nacelle 16, as well as the total load generated by the wind and rotational loads, and to introduce these loads into the tower 15 of the wind turbine 10. The rotor shaft 44, generator 42, gearbox 46, high-speed shaft 48, coupling 50, and associated fastening, support, and / or fixing devices, including but not limited to the support 52, front support bearing 60 and rear support bearing 62, may be referred to as the drive train 64.

[0030] In some examples, the wind turbine may be a direct-drive wind turbine without a gearbox 46. The generator 42 operates at the same rotational speed as the rotor 18 of the direct-drive wind turbine. Therefore, they generally have a much larger diameter than the generators used in wind turbines with a gearbox 46 to supply the same amount of power as those used in wind turbines with a gearbox.

[0031] Furthermore, the nacelle 16 may include a yaw drive mechanism 56 that can be used to rotate the nacelle 16, and by extension the rotor 18, around the yaw axis 38, in order to control the proximity of the rotor blades 22 to the wind direction 28.

[0032] To properly position the nacelle 16 with respect to the wind direction 28, the nacelle 16 may also include at least one weather measurement system 58 which may include a wind vane and an anemometer. The weather measurement system 58 can provide the wind turbine control device 36 with information including the wind direction 28 and / or wind speed. In this example, the pitch system 32 is at least partially located as a pitch assembly 66 within the hub 20. The pitch assembly 66 includes one or more pitch drive systems 68 and at least one sensor 70. Each pitch drive system 68 is coupled to each rotor blade 22 (shown in Figure 1) to modulate the pitch angle of the rotor blade 22 along the pitch axis 34. Figure 2 shows only one of the three pitch drive systems 68.

[0033] In this example, the pitch assembly 66 includes a hub 20 and at least one pitch bearing 72 coupled to each rotor blade 22 (shown in Figure 1) to rotate each rotor blade 22 around the pitch axis 34. The pitch drive system 68 includes a pitch drive motor 74, a pitch drive gearbox 76, and a pitch drive pinion 78. The pitch drive motor 74 is coupled to the pitch drive gearbox 76 so that the pitch drive motor 74 imparts mechanical force to the pitch drive gearbox 76. The pitch drive gearbox 76 is coupled to the pitch drive pinion 78 so that the pitch drive pinion 78 is rotated by the pitch drive gearbox 76. The pitch bearing 72 is coupled to the pitch drive pinion 78 so that the pitch bearing 72 is rotated by the rotation of the pitch drive pinion 78.

[0034] The pitch drive system 68, upon receiving one or more signals from the wind turbine controller 36, is coupled to the wind turbine controller 36 to adjust the pitch angle of the rotor blades 22. In embodiments, the pitch drive motor 74 is any suitable motor driven by an electric and / or hydraulic system, enabling the pitch assembly 66 to function as described herein. Alternatively, the pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components, such as hydraulic cylinders, springs, and / or servo mechanisms, but is not limited to these. In certain embodiments, the pitch drive motor 74 is driven by the rotational inertia of the hub 20 and / or energy extracted from a stored energy source (not shown) that supplies energy to the components of the wind turbine 10.

[0035] The pitch assembly 66 may also include one or more pitch control systems 80 for controlling the pitch drive system 68 in accordance with a control signal from the wind turbine controller 36 in certain prioritized situations and / or during overspeed of the rotor 18. In this example, the pitch assembly 66 includes at least one pitch control system 80 communicably coupled to each pitch drive system 68 in order to control the pitch drive system 68 independently of the wind turbine controller 36. In this example, the pitch control system 80 is coupled to the pitch drive system 68 and the sensor 70. During normal operation of the wind turbine 10, the wind turbine controller 36 may control the pitch drive system 68 to adjust the pitch angle of the rotor blades 22.

[0036] In one embodiment, for example, a generator 84 including a battery and an electric capacitor is located inside or within the hub 20 and coupled to a sensor 70, a pitch control system 80, and a pitch drive system 68 to provide a power source to these components. In this embodiment, the wind turbine generator 84 provides a continuous source of power to the pitch assembly 66 while the wind turbine 10 is in operation. In another embodiment, the generator 84 supplies power to the pitch assembly 66 only during power loss events of the wind turbine 10. Power loss events may include power grid losses or dips, malfunctions of the wind turbine 10's electrical system, and / or failures of the wind turbine controller 36. During a power loss event, the generator 84 operates to supply power to the pitch assembly 66 so that the pitch assembly 66 can operate during the power loss event.

[0037] In this embodiment, the pitch drive system 68, sensor 70, pitch control system 80, cable, and generator 84 are each located within a cavity 86 defined by the inner surface 88 of the hub 20. In another embodiment, the components are located relative to the outer surface of the hub 20 and may be directly or indirectly coupled to the outer surface.

[0038] Figures 3 and 4 show front and rear perspective views, respectively, of an example of a stator assembly for an electric machine. In any of the following embodiments, the electric machine may be a generator, and in any of the following embodiments, the generator may be a wind turbine generator, and in particular a direct-drive wind turbine generator.

[0039] The stator assembly includes a plurality of stator frames 110, 120, 130 that define a ring sector. The stator frames 110, 120, 130 are mounted together to form a stator rim 100. The stator rim 100 is configured to carry electromagnetically active stator elements (not shown) and has a radially outward 140 facing the air gap between the stator assembly and the rotor of the electromechanical unit. The plurality of stator frames 110, 120, 130 form at least partially an air distribution channel. The air distribution channel extends from at least one of the stator frames 110, 120, 130 to another of the stator frames 110, 120, 130. Thus, the air distribution channel is configured to distribute air along the circumferential direction of the stator rim 100.

[0040] In some examples, the stator frames 110, 120, and 130 may include radial end walls 200 that separate the respective ring sectors in the circumferential direction. The radial end walls 200 provide strength and rigidity to the stator frames 110, 120, and 130. Furthermore, the radial end walls 200 may have air distribution orifices 201 to facilitate tangential air distribution around the inside of the stator rim 100.

[0041] Radial end walls can be configured to connect adjacent stator frames to one another. For this purpose, radial end walls may include openings or holes for receiving fasteners such as bolts or studs, or other openings or holes for connecting to one another.

[0042] In some examples, the stator assembly may include side walls 160, 170 that divide the stator rim 100 in the longitudinal direction LD. As shown in Figures 3 and 4, the side walls 160, 170 may be formed integrally with the stator frames 110, 120, 130. Alternatively, the side walls 160, 170 may be independent components connected to the stator frames 110, 120, 130. The side walls 160, 170 at least partially enclose the stator rim 100 and contribute to tangential airflow circulation within the stator rim.

[0043] In the examples shown in Figures 3 and 4, the stator assembly can be positioned radially inside the generator rotor, i.e., the generator rotor can radially surround the generator stator. As shown in Figures 3 and 4, the stator assembly can define a radially outside 140 including a radial boundary wall and a radially inside 150 not including such a boundary wall. In this example, the radially inside wall is omitted to better visualize the internal elements, i.e., the radial end wall 200. Such a boundary wall may also be present in the stator assembly of this disclosure or may be part of an independent generator structure. Here, the terms “radially inside” and “radially outside” are used merely for illustrative purposes. In fact, the technical features of these radial sides may be reversed in the case of an electromachine in which the stator assembly surrounds the rotor.

[0044] Furthermore, Figure 3 shows that the stator frames 110, 120, 130 forming the stator rim 100 may further include structural elements 210 distributed in the circumferential direction. Examples shown in Figures 3 and 4 show that the structural elements 210 may be flanges substantially contained within a plane perpendicular to the circumferential direction. Furthermore, the flanges may include air distribution orifices 211. The shape, number, and distribution of the structural elements around the stator rim 100 may vary depending on the specific requirements of the stator assembly. For example, the structural elements may be beams arranged circumferentially. Alternatively, the structural elements may be arranged without circumferential symmetry to provide dedicated free space for additional components. In other examples, the structural elements may be flanges contained within a plane at an angle to the circumferential direction.

[0045] Furthermore, Figures 3 and 4 also show that the exemplary stator assembly includes one or more openings 180 that receive an air inlet (not shown) located on the first side wall 160 and one or more air outlets 190 located on the second side wall 170. In this example, the second side wall 170 may be located on the driven side (i.e., the side where a wind turbine rotor for driving the generator rotor may be located) and the first side wall 160 may be located on the non-driven side.

[0046] In this embodiment shown in Figures 3 and 4, the openings 180 and air outlets 190 are simply illustrated as orifices within the side walls 160 and 170. However, the openings 180, air inlets, and air outlets 190 can include streamlined shapes to provide smooth inflow and outflow transitions into and from the stator assembly. Furthermore, the number and distribution of the openings 180 (and their respective air inlets) and air outlets 190 may differ from the illustrated example. For example, a stator assembly including multiple stator frames 110, 120, and 130 is possible, where at least one of the stator frames 110, 120, and 130 does not include an air inlet. For this purpose, it should be noted that all stator frames 110, 120, and 130 do not necessarily have to be identical. Possible distributions of the air inlets and air outlets 190 will be discussed in more detail with respect to Figure 6.

[0047] Figure 4 also shows that the second side wall 170 includes a recessed area configured to receive a connecting plate 172. The connecting plate 172 may be used to connect the side walls 170. Thus, the side walls of the stator assembly can be composed of several wall segments, resulting in improved ergonomics and manufacturability, as well as simplified maintenance work by removing such wall segments. The connecting plate 172 can be placed on the recess and secured to adjacent wall segments by bolts or similar fasteners. Although not shown in Figure 4, the spaces between wall segments may be sealed to maintain a protected environment inside the generator. Such spaces can be sealed using silicone.

[0048] Figure 5 is a detail view of an example of a radial end wall 200 of an exemplary stator frame. As shown in Figure 5, the radial end wall 200 may include multiple air distribution orifices 201, 202, 203. Furthermore, Figure 5 also shows that air distribution orifices 211, 212 of the flange 210 may be substantially aligned circumferentially with the air distribution orifices 201, 202 of the radial end wall 200. Furthermore, Figure 5 also shows that the aligned air distribution orifices, i.e., 201-211, 202-212, may have similar shapes and sizes. Thus, this orifice distribution leaves an obstruction-free circumferential path that facilitates air to flow circumferentially. In other examples, the structural elements may be beams positioned so that there are no obstructions, or at least substantially no obstructions, in the aforementioned circumferential path.

[0049] Furthermore, Figure 5 shows that the radial end wall 200 can define two structural load paths (structural load paths) 205 and 206. Here, the structural load paths are shown as dashed lines, which should be understood as the path along the radial end wall 200 from the load acting on the circumferential side 140 (radially outward in this case) to the radially inward side 150, and vice versa. In this embodiment, the load paths 205 and 206 connect the radially outward side 140 to the radially inward side 150 by following substantially linear paths along the radial end wall 200. Similar load paths may be formed on the flange 210, as will be discussed with respect to Figure 6.

[0050] The embodiment shown in Figure 5 also demonstrates that the two structural load paths 205, 206 can form angles with respect to each other between 40 and 70 degrees, particularly between 50 and 60 degrees. This angular range allows for efficient distribution of the load to different components, thereby increasing the strength capacity of the stator assembly. The load paths 205, 206 are formed from material that is substantially continuous in the linear direction. Thus, the load paths 205, 206 can have orifices 201, 202, 203 that at least partially define their boundaries on the sides.

[0051] Furthermore, the multiple air distribution orifices 201, 202, 203 of the radial end wall 200 may include a substantially triangular main orifice 201. The main orifice 201 may have an end substantially parallel to the radially outer 140 of the stator rim 100 and two other ends parallel to two load path directions 205, 206. Furthermore, the substantially triangular main orifice 201 may include rounded corners to reduce local stresses that may potentially affect the integrity of the radial end wall 200. Specifically, the radius of curvature of the rounded corners of the main orifice 201 is 10% to 35% of the height of the main orifice, more specifically, 15% to 30% of the height of the main orifice.

[0052] Furthermore, the multiple air distribution orifices may include secondary orifices 202, 203 having substantially straight edges parallel to one of the load path directions 205, 206. In particular, the secondary orifices 202, 203 may have a substantially triangular shape and may also include rounded corners to relieve local stress. The radius of curvature of the rounded corners of the triangular secondary orifices 202, 203 may be between 30% and 60% of the height of the secondary orifice. The secondary orifices 202, 203 may be smaller than the main orifice 201.

[0053] As described above, the technical features related to the radial end walls 200 of the stator frames 110, 120, and 130 may be included in the stator rim 100, or may be part of a separate component coupled to the stator frames 110, 120, and 130 or the stator rim 100.

[0054] The embodiment shown in Figure 5 also shows that the radial end wall 200 may further include receptacles 204 for receiving fasteners. Furthermore, the stator assembly may further include fasteners. The fasteners can connect the stator frames 110, 120, and 130 to one another. The receptacles 204 may be positioned around the radial end wall 200. In some examples, the receptacles 204 may be through holes, and in other examples, the receptacles 204 may be blind screw holes. In other embodiments, the receptacles 204 may be a combination of through holes and blind screw holes. Furthermore, the side wall (a second side wall 170 in this example) may include additional receptacles 171 for connecting a joining plate 172 (shown in Figure 4) between the side wall segments.

[0055] Figure 6 is a detailed cross-sectional view of a wind turbine generator. In the illustrated embodiment, the wind turbine generator 42 includes a rotor 300 and a stator assembly according to the present disclosure. Figure 6 shows an exemplary cooling air flow path, where dashed arrows represent relatively cold air and solid arrows represent relatively warm air. As shown, cooling air can be supplied to the stator assembly via an air inlet 188. Once the air enters the stator assembly, air distribution orifices 201, 202, 203 in the radial end wall 200 (not shown here) and air distribution orifices 211, 212, 213 in the flange 210 allow the cooling air to move circumferentially along the air distribution channels and around the stator assembly before exiting the stator assembly through the air outlet 190. The airflow then flows around the stator assembly and between the rotor 300 and the stator rim 100 of the stator assembly before being collected by the air outlet. More specifically, the airflow flows along the air gap between the active rotor section 301 and the active stator section 141. The active parts of the stator and rotor may be permanent magnets, coils, windings, or combinations thereof. Thus, the air distribution channel allows for efficient cooling around the stator rim 100 to compensate for the uneven distribution of a limited number of air inlets 188 and air outlets 190. This allows for the arrangement of multiple configurations, namely symmetrical and asymmetrical configurations, for space limitations or other operating requirements.

[0056] In another aspect of this disclosure, a stator assembly for an electromechanical device is disclosed. The stator assembly includes a plurality of ring sectors 110, 120, 130 mounted together to form a stator rim 100. The ring sectors 110, 120, 130 are configured to carry electromagnetically active stator elements and include sectors of the stator rim 100 having circumferential sides facing an air gap with respect to a rotor. The stator rim 100 also has a first side wall 160 on a first axial side of the electromechanical device and a second side wall 170 on a second axial side. The stator rim 100 also has a first radial end wall 200 at a first circumferential end of the ring sector and a first radial end wall at a second circumferential end of the ring sectors 110, 120, 130. The first and second radial end walls 200 also include one or more air distribution orifices 211, 212, 213. Therefore, the stator assembly defines air distribution paths that promote tangential air distribution within and around the stator assembly.

[0057] Furthermore, the air distribution orifices may be aligned and may have similar shapes and sizes. More specifically, Figure 6 shows that orifices 211, 212, and 213 within flange 210 can be substantially replicated in subsequent flanges. Furthermore, Figure 6 also shows that the air distribution orifices 211, 212, and 213 (within flange 200 and within radial end wall 200) substantially define two structural load paths 205 and 206 from the radially outer 140 to the radially inner 150 of the circumferential rim 100.

[0058] In another embodiment of this disclosure, Method 400 is provided, which is suitable for assembling a stator assembly. Method 400 is schematically shown in Figure 7.

[0059] The method includes providing at least two stator frames 110, 120, 130 in block 401. Each stator frame 110, 120, 130 forms a ring sector and at least partially forms an air distribution channel for distributing air circumferentially across the stator frames 110, 120, 130. Furthermore, the method 400 includes the step of joining the stator frames 110, 120, 130 to each other in block 402 to form a circumferential rim.

[0060] In this regard, the stator frames 110, 120, and 130 can define ring sectors having different arc angles, namely, the first stator frame can define a ring sector having a 90-degree arc angle, the second stator frame can define a ring sector having a 270-degree arc angle, the first stator frame can define a ring sector having a 180-degree arc angle, the second stator frame can define a ring sector having a 180-degree arc angle, or any other combination.

[0061] According to this embodiment, a stator peripheral rim 100 formed by a plurality of independent stator frames 110, 120, 130 can be assembled. The independence of the stator frames 110, 120, 130 reduces the overall complexity of manufacturing the stator rim 100. Furthermore, it simplifies the logistics associated with its storage and transport, while simultaneously reducing the lifting requirements of the associated equipment during transport.

[0062] In the embodiment, the stator frames 110, 120, and 130 provided in block 401 further include radial end walls 200 that circumferentially divide the stator frames 110, 120, and 130, and flanges 210 between the radial end walls 200. The radial end walls 200 and flanges 210 may include circumferentially aligned air distribution orifices 211, 212, and 213. Furthermore, the coupling step in block 402 can be carried out by inserting fasteners onto receptacles 204 located on the radial end walls 200. Alternatively, the stator frames 110, 120, and 130 can be coupled using connecting plates 172. These additional steps of Method 400 allow the stator assembly to be fixed in place before operating the electromachine, providing a secure and easily accessible coupling.

[0063] Any technical features described with respect to the stator assembly or any of its components may also be included in the method 400 for assembling the stator assembly.

[0064] The descriptions herein use examples to disclose teachings including preferred embodiments and to enable a person skilled in the art to implement the teachings disclosed herein, including manufacturing and using any apparatus or system and implementing any incorporated methods. The patentable scope is defined by the claims and may include other examples arising to a person skilled in the art. Such other examples are intended to be within 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 are not substantially different from the literal language of the claims. Aspects from the various embodiments described, as well as other known equivalents to each such aspect, may be mixed and harmonized by a person skilled in the art to construct additional embodiments and techniques in accordance with the principles of this application. Where reference numerals relating to drawings are enclosed in parentheses within the claims, they are intended solely to increase the understanding of the claims and should not be construed as limiting the claims. [Explanation of Symbols]

[0065] 10: Wind turbine 12: Ground 14: Support system 15: Tower 16: Nacelle 18: Rotor 20: Hub 22: Rotor blade 24: Blade root 26: Load transfer area 28: Wind direction 30: Rotor shaft 32: Pitch system 34: Pitch shaft 36: Wind turbine control device 38: Yaw shaft 42: Generator 44: Main shaft 46: Gearbox 48: High-speed shaft 50: Coupling 52: Main frame 54: Decoupling support means 56: Yaw drive mechanism 58: Weather measurement system 60: Main front support bearing 62: Rear support bearing 64: Drive train 66: Pitch assembly 68: Pitch drive system 70: Sensor 72: Pitch bearing 74: Pitch drive motor 76: Pitch drive gearbox 78: Pitch drive pinion 80: Pitch control system 84: Generator 86: Cavity 88: Inner surface 90: Transformer 100: Stator rim 103: Torque arm 110,120,130: Stator frame 140: Radial outer surface 141: Active stator component 150: Radial inner surface 160,170: Side wall 171: Additional receptacle 172: Joint plate 180: Opening 188: Air inlet 190: Air outlet 200: Radial end wall 201,202,203: Distribution orifice 204: Receptacle 205,206: Structural load path 210: Structural element flange 211,212,213: Air distribution orifice 300: Rotor 301: Active rotor section LD: Longitudinal direction

Claims

1. 1. A stator assembly for an electric machine comprising: a stator and a rotor (300) having an axis of rotation along a longitudinal direction (LD) and a radial air gap between the stator and rotor (300), a plurality of stator frames (110, 120, 130) defining a plurality of ring sectors and attached to one another to form a stator rim (100), the stator rim (100) being configured to support electromagnetically active stator elements (141) and having a circumferential side (140) facing an air gap, the plurality of stator frames (110, 120, 130) at least partially forming an air distribution channel; an air distribution channel extending from at least one of the stator frames (110, 120, 130) to the other of the stator frames (110, 120, 130) to distribute air along the circumferential direction of the stator rim (100); Including, At least one stator frame (110, 120, 130) has radial end walls (200) circumferentially delimiting each ring sector and has air distribution orifices (201, 202, 203); the radial end walls (200) define two structural load paths (205, 206) from the radially outer side to the radially inner side of the stator frame (110, 120, 130), the structural load paths (205, 206) being substantially straight; A stator assembly, wherein the air distribution orifices (201, 202, 203) include a substantially triangular main orifice (201) with rounded corners, an edge of the triangle being substantially parallel to the radially outer side of the stator frame, and the other two edges being substantially parallel to two load path directions (205, 206).

2. The stator assembly of claim 2, wherein the plurality of stator frames are configured to be joined at radial end walls (200).

3. 2. The stator assembly of claim 1, wherein the two structural load paths (205, 206) form an angle with each other between 40 and 70 degrees, or between 50 and 60 degrees.

4. 2. The stator assembly of claim 1, wherein the radius of curvature of the rounded corners of the main orifice (201) is between 10% and 35% of the height of the main orifice, specifically between 15% and 30% of the height of the main orifice.

5. 2. The stator assembly of claim 1, wherein the air distribution orifices (201, 202, 203) include one or more secondary orifices (202, 203), the secondary orifices being smaller than the primary orifices.

6. 6. The stator assembly of claim 5, wherein the secondary orifices (202, 203) are generally triangular in shape and have generally straight edges parallel to one of the load path directions (205, 206).

7. The stator assembly of claim 1, further comprising side walls (160, 170) separated from one another along the longitudinal direction (LD) and delimiting the stator rim (100) in the longitudinal direction (LD).

8. The stator assembly of claim 7, wherein the side walls (160, 170) are integrally formed with the stator frame (110, 120, 130).

9. 8. The stator assembly of claim 7, wherein one or more air inlets (188) are disposed on the first sidewall (160) and one or more air outlets (190) are disposed on the second sidewall (170).

10. A generator including a stator assembly according to any one of claims 1 to 9.

11. A direct drive wind turbine including the generator of claim 10.

12. A method (400) for assembling a stator assembly, comprising: providing (401) at least two stator frames (110, 120, 130) defining ring sectors; (402) joining the stator frames (110, 120, 130) at their radial end walls to form a stator rim (100); Including, Each stator frame (110, 120, 130) at least partially defines an air distribution channel that distributes air circumferentially across the stator frame (110, 120, 130), the radial end wall (200) including air distribution orifices (201, 202, 203); The radial end wall (200) is provided with air distribution orifices (201, 202, 203), the radial end walls (200) define two structural load paths (205, 206) from the radially outer side to the radially inner side of the stator frame (110, 120, 130); the structural load paths (205, 206) are substantially straight; the main orifice (201) of the air distribution orifices (201, 202, 203) is substantially triangular in shape with rounded corners; The method wherein an edge of the triangle is substantially parallel to the radially outer side of the stator frame, and the other two edges are substantially parallel to the two load path directions (205, 206).

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