Wind turbine generator and wind turbine comprising such a generator

Abstract

Wind turbine generator comprising an inner stator (3) and an outer rotor (1), the outer rotor (1) comprising a cylindrical rotor yoke (4), wherein several cooling elements (6) are attached to the outer lateral surface of the rotor yoke (4), wherein the cooling elements (7) are cooling fins (7), the cooling fins (7) comprising a plate-like attachment base (8) attached to the outer side of the rotor yoke (4) and a fin part (9) extending at an angle from the attachment base (8).

Description

Technical Field

[0001] The present invention relates to a wind turbine generator, comprising an inner stator and an outer rotor, the outer rotor comprising a cylindrical rotor yoke, wherein a plurality of cooling elements are attached to the outer surface of the rotor yoke. Background Technology

[0002] Wind turbines typically consist of a wind turbine generator. The generator is driven by a rotor blade arrangement comprising multiple rotor blades attached to a hub, which is connected to the generator's rotor. A specific type of turbine is the direct-drive wind turbine, which includes a generator with an inner stator and an outer rotor, the outer rotor being directly driven by the hub without intermediate gears. The rotor includes multiple magnetic elements attached to the inner circumference of a cylindrical rotor yoke; in larger generators, the rotor yoke can have a diameter of several meters, up to 10 meters or more. The temperature of the magnetic elements rises due to induced eddy currents in the permanent magnet elements and / or heat from the stator due to stator losses. This problem is particularly noticeable in generators with rotors having concentrated windings, but it can also be relevant to generators with rotors having distributed windings. To avoid any irreversible demagnetization and to improve generator performance, it is necessary to control the temperature of the magnetic elements. To address this problem, it is known to attach cooling elements to the outer surface of the rotor yoke, such as those disclosed, for example, in EP 2 445 087 B1. These cooling elements, in the form of longitudinal rods with rectangular cross-sections, are attached to the inner surface of the rotor yoke and directly connected by fastening devices to magnet elements disposed on the inner surface. This direct connection allows heat transfer from the magnet elements to the cooling elements. This arrangement is somewhat complex, and the cooling power is controllable. Summary of the Invention

[0003] One object of the present invention is to provide a wind turbine generator having an improved cooling arrangement for cooling the rotor or rotor yoke.

[0004] Before achieving this objective, the wind turbine generator described above is characterized by having cooling elements that are cooling fins, which include a plate-shaped attachment base attached to the outside of the rotor yoke and fin components extending from the attachment base at an angle.

[0005] The generator of the present invention is preferably a direct-drive generator and may include a concentrated winding. It includes a rotor with a very simple but highly effective cooling arrangement. The rotor yoke is equipped with a plurality of cooling elements, which are cooling fins, attached to its outer surface. Each cooling fin, being a metallic article, includes a plate-shaped attachment base and a fin component extending from the attachment base at an angle such that it extends away from the outer surface of the rotor yoke in its mounting position. The cooling fin is attached to the rotor yoke via its attachment base, which provides a sufficiently large attachment surface. This allows for a sufficiently stable connection that also withstands the high loads caused by the high rotational speed of the rotor. From this flat, plate-shaped attachment base, the fin component extends in a direction away from the outer surface of the rotor yoke into the free space surrounding the rotor yoke. This fin provides a sufficiently large surface area, which allows for a high rate of heat transfer from the cooling fin or fin component to the surrounding area. The fin component may be plate-shaped with a longitudinal cross-section, but it may also be slightly curved. The length of the fin component is preferably greater than the length of the attachment base viewed in the circumferential direction of the yoke. There are virtually no restrictions on the length of the finned components extending into the surrounding space, which allows for an increase in the heat transfer properties of the cooling fins, thereby increasing the heat transfer surface area of ​​the finned components, simply by using longer finned components. In generator operation, the magnetic elements are heated due to their eddy currents and / or stator heat. At least a portion of this heat is transferred to the rotor yoke, made of a metal such as steel or cast metal, from where it is transferred to the attachment base, which is then heated. The heat is then transferred to the finned components extending in the open space surrounding the rotor yoke. Due to the large heat transfer area of ​​the finned components, heat can be perfectly transferred to the surrounding area, thus achieving a highly improved heat transfer from the magnetic elements to the finned components and from them to the surrounding environment. This improved heat transfer allows the temperature of the magnetic elements to be maintained sufficiently low and away from the critical temperature, where irreversible demagnetization may occur, during process operation. Furthermore, the cooling arrangement of the present invention, including the cooling fins, is a simple arrangement because the longitudinal cooling fins are simply attached to the outer surface. There is no need to connect them to the inside of the rotor yoke, nor is it necessary to connect them to the underlying magnetic elements for heat transfer as in the prior art discussed above. Therefore, the rotor yoke or rotor of the generator of the present invention is simplified and cheaper.

[0006] Preferably, the plate-shaped fin components extend at any angle suitable for maximizing heat dissipation, such as an angle of 45-135°, more specifically 60-120°, and especially at a 90° angle to the attachment base. Thus, the fin components are arranged radially and extend radially from the outer surface of the rotor yoke.

[0007] As mentioned, cooling fins are simple metal articles comprising only an attachment base and fin components. Therefore, such cooling fins can have simple T-shaped or L-shaped cross-sections. These metal articles can be supplied in standard profiles while also possessing the required mechanical properties regarding stiffness, dimensions, heat transfer coefficients, etc. This further contributes to the simplification of the invention design and the reduction of manufacturing costs.

[0008] As mentioned, the length of the fin component in the radial direction is preferably greater than the width of the attachment base in the circumferential direction. The width of the attachment base is selected to ensure that the cooling fins are sufficiently stably fixed to the rotor yoke. According to a preferred embodiment, the fin component is provided with an enlarged surface profile. As mentioned, the central purpose of the fin component is to provide a large heat transfer surface. When the fin component does not have a flat surface but has a profiled surface, this surface can be enlarged. The profiled surface can exhibit a wavy profile on one or both sides of the fin component, or a recessed profile with multiple recesses on one or both sides. This profiled surface design can significantly enlarge the total surface area, which significantly increases the heat transfer power.

[0009] Preferably, the cooling element may extend parallel to or at an angle of some degree (e.g., up to + / - 30°) relative to the rotor's axis of rotation, and extend along any length of the rotor yoke, for example, at least half or the entire length of the rotor yoke. As mentioned, the rotor yoke is a cylindrical metal article having a specific length of, for example, one meter or more, and a diameter of one meter or more. Magnetic elements, typically permanent magnets, preferably extend along almost the entire length of the rotor yoke.

[0010] In a preferred embodiment, the outer surface of the rotor yoke is provided with a recess having a flat, planar bottom, in which the attachment base is received. As mentioned, the rotor yoke is cylindrical and therefore has a cylindrical outer surface. Depending on the diameter, the outer surface is more or less curved. To allow for perfect attachment and heat transfer contact between the cooling element and the rotor yoke, the outer surface of the rotor yoke is provided with a low recess machined into the outer surface, the recess having a flat, planar bottom. Since the attachment base is also plate-shaped and has a flat attachment surface, a corresponding surface geometry is provided, simplifying the attachment of the cooling element, as the radius of any of these surfaces does not affect the connection and heat transfer.

[0011] According to a preferred embodiment, an intermediate heat transfer layer is provided between the outer surface and the attachment base. This heat transfer layer provides improved heat transfer from the rotor yoke to the attachment base. When the rotor yoke and cooling element are made of different metals, such as the rotor yoke being made of steel and the cooling element being made of aluminum, this layer also serves as a separation layer. Using two different metals and bringing them into direct contact can provide localized components that may be prone to corrosion in the presence of moisture. This can be advantageously avoided when an intermediate heat transfer layer is provided, as it completely separates the rotor yoke from the cooling element, eliminating direct contact.

[0012] The heat transfer layer can be a thermally conductive paste, which can be applied over the entire contact area, such as the entire recessed area and / or the attachment surface of the attachment base. This paste can further remove any cavitation in the area between the contact surfaces. Alternatively, the heat transfer layer can also be a polymer-based foil or sheet, such as a pad, sandwiched between the rotor yoke and the attachment base, and, if desired, can be applied using an adhesive. The heat transfer layer exhibits good heat transfer properties with a high heat transfer coefficient.

[0013] Preferably, the attachment base is secured to the rotor yoke by means of screws, which are screwed into threaded blind holes provided in the rotor yoke. Alternatively, the attachment base is secured to the rotor yoke by welding or gluing. According to the first alternative, the rotor yoke is provided with a plurality of threaded blind holes or blind holes on its outer surface. The attachment base is provided with a corresponding number of through holes. To secure the cooling element, screws extending through the through holes are screwed into the threaded blind holes, allowing for perfect fixation. Of course, the screws can be additionally secured, for example by additionally gluing them into corresponding through holes and / or threaded blind holes or by using other securing devices. The screws are arranged at least along the longitudinal side of the attachment base, and their number is selected according to the mechanical requirements regarding mechanical fixation. According to the second alternative, the cooling element or attachment base can also be welded to the outer surface of the rotor yoke. The welding process and welding materials are selected according to the materials of the rotor yoke and the cooling element. Finally, according to the third alternative, the cooling element or attachment base can be glued to the outer surface of the rotor yoke by means of a suitable adhesive with good thermal conductivity.

[0014] A further feature of wind turbine generators is that a sealing device is disposed in the transition zone from the attachment base to the outer surface and / or from the screw to the attachment base. This sealing device provides a waterproof seal, preventing moisture or dust from entering the sealed area. The sealing device, for example, can be a polymer- or silicone-based paste or any other suitable sealing device, simply attached to the transition zone, which contacts both the rotor yoke and the attachment base, or both the attachment base and the screw, wherever it is applied. By using this sealing device, any small gaps that may exist between any contact mating parts can be sealed. When the attachment base is welded to the rotor yoke, a sealing device may not be necessary in the weld area because the weld is tight along its length.

[0015] As already mentioned, the rotor yoke has multiple magnetic elements, preferably permanent magnets, arranged on its inner side. Generally, the more cooling elements there are, the better the cooling power, because the total heat transfer surface area provided by the finned components is larger. The number of cooling elements can correspond to the number of magnets, such that a cooling element is provided for each magnet. Other arrangements are also possible, such as one cooling element for every second, third, or fourth magnet element.

[0016] Preferably, at least some of the cooling fins are arranged radially flush with the magnetic element. For excellent heat transfer and a short transfer length, the cooling elements or cooling fins are arranged radially flush with the underlying magnetic element, so that heat needs to be transferred over only a very short length in the radial direction. Preferably, the number of cooling elements corresponds to the number of magnetic elements, such that radially flush cooling elements are provided for each magnetic element. Of course, only some cooling elements are arranged flush with the corresponding magnetic element, while other cooling elements are randomly distributed around the circumference relative to the magnetic elements arranged at the inner circumference. However, all cooling elements are preferably uniformly distributed around the outer circumference, such that the distance between two cooling elements is always the same in the circumferential direction.

[0017] Cooling elements are made of aluminum, preferably corrosion-resistant aluminum. Aluminum has excellent heat transfer properties, possessing a sufficiently high coefficient of thermal conductivity or thermal conductivity. These properties are accompanied by lower weight compared to cooling elements made of steel. Therefore, the cooling elements do not significantly contribute to the total weight of the rotor, and thus do not significantly increase the forces acting on the corresponding bearings and shafts. Corrosion-resistant aluminum is preferred. When wind turbines are located at sea, the air or moisture is salty, which can enhance corrosion. Using corrosion-resistant aluminum can prevent any corrosion. Of course, other materials can also be used, but corrosion-resistant materials are preferred, such as suitable metal alloys based on steel or aluminum.

[0018] In addition to the wind turbine generator, the present invention also relates to a wind turbine that includes the wind turbine generator as described above. Attached Figure Description

[0019] Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, the drawings are merely schematic diagrams designed for illustrative purposes only and do not limit the invention. In the drawings: Figure 1 These are the main illustrations and partial perspective views of the rotor of the wind turbine generator of the present invention; Figure 2 yes Figure 1 An enlarged view of the outer surface of the rotor yoke of the rotor. Figure 3 This is a main cross-sectional view of a portion of the rotor of the generator of the present invention. Figure 4 This is an example of a cross-section of the cooling element in the first embodiment. Figure 5 This is an example of a cross-section of the cooling element in the second embodiment. Figure 6 This is an example of a cross-section of the cooling element in the third embodiment, and Figure 7 This is a main illustration of the wind turbine of the present invention, including the generator of the present invention. Detailed Implementation

[0020] Figure 1 This diagram shows the main features of the rotor 1 of the wind turbine generator 2 of the present invention. Figure 7 The main features are shown in the diagram. In addition to the rotor 1, the generator 2 also includes an inner stator 3, wherein the rotor 1 extends outward around the inner stator 3.

[0021] The rotor 1 includes a rotor yoke 4 having a cylindrical geometry. On the outer surface 5, a plurality of longitudinal cooling elements 6 extend parallel to the rotation axis of the rotor 1. The cooling elements 6 extend over at least half the length of the rotor yoke 4, such as... Figure 1 As shown in the image.

[0022] Each cooling element 6 is made of aluminum, preferably corrosion-resistant aluminum, but other good thermally conductive materials, preferably corrosion-resistant materials, can also be used. It is a longitudinal article and is implemented as cooling fins 7, the details of which are... Figure 2 and Figure 3 As shown in the figure. Each cooling fin 7 includes a plate-shaped attachment base 8. A fin member 9 (which is also plate-shaped in the illustrated embodiment) extends from the attachment base at an angle (90° in the illustrated example) such that, when installed, the fin member 9 extends into the surrounding space. Therefore, the cooling fin 7 has a T-shaped profile, especially as shown in the figure. Figure 3 As shown in the image.

[0023] The outer surface 5 of the rotor yoke 4 is provided with a plurality of recesses 10 corresponding to the number of cooling fins 7 attached to the rotor yoke 4. Each recess 10 includes a flat, planar bottom 11. Since the attachment base 8 also has a flat, planar attachment surface 12, corresponding adjacent surfaces have the same geometry. The recesses 11 can have a depth of, for example, 1-10 mm, therefore the thickness of the attachment base 8 is greater than the depth of the recesses 11, such as... Figure 3 As shown in the diagram. To enhance heat transfer from, for example, a metal rotor yoke 4 made of steel to the cooling fins 7, an intermediate heat transfer layer 13 is arranged between the bottom 10 and the attachment surface 12. This heat transfer layer 13 is preferably thermal paste, thermal gap filler, or thermal pad, which, in addition to enhancing heat transfer, eliminates any interfacial cavitation, making perfect heat transfer possible.

[0024] To attach the cooling fins 7 to the rotor yoke 10, the rotor yoke 10 is provided with threaded blind holes 14, and the attachment base 8 is provided with corresponding through holes 15. Screws 16 are used to secure the cooling fins 7. They extend through the through holes 15 and are screwed into the threaded blind holes 14, thus firmly fixing the attachment base 8 to the rotor yoke 4. The screw connection achieved by the screws 16 can be additionally secured by appropriate fastening devices such as glue or small solder joints, thereby preventing any unintended loosening of the screws 15. Figure 2 As shown, multiple screws 16 are provided on the two longitudinal sides of each attachment base 8 to provide a perfect fastening.

[0025] like Figure 3 As further shown, a sealing device 17 is disposed in the transition area between the attachment base 8 and the outer surface 5 of the rotor yoke. This sealing device is a waterproof seal and is applied around the entire circumference of the attachment base 8 to prevent any dust or water from entering the fixed area. Any such sealing device may also be disposed in the corresponding threaded connection, such as glue or sealant or sealing gasket, etc.

[0026] In addition, see Figure 3 The rotor 1 includes a plurality of magnetic elements 18, which are attached to the inner surface 20 of the rotor yoke 4 via corresponding base plates 19. The magnetic elements 18 are preferably permanent magnets. Figure 3As shown, at least a portion of the cooling fins 7, or cooling fins 7 distributed circumferentially, are radially flush with the magnet elements 18 arranged on the inner side of the rotor yoke 4. This enhances heat transfer from the magnet elements 18, which are heated by eddy currents when the generator is in operation, because due to the radial correlation between the cooling fins 7 and the magnet elements 18, the heat to be transferred to the cooling fins 7 only needs to be transferred over a small distance that almost corresponds to the thickness of the rotor yoke 4. Preferably, all the cooling fins 7 are readily flush with the magnet elements 18, such that the number of cooling fins 7 corresponds to the number of magnet elements 18. However, the number can also be different (e.g., fewer cooling fins 7 than magnet elements 18), and accordingly, the arrangement of all the cooling fins 7, or at least a portion thereof, can be independent of the position of the magnet elements 18.

[0027] Figure 4 The cooling fins 7 of the first embodiment are shown, as already illustrated. Figure 3 As shown in the figure, it includes an attachment base 8 and a fin member 9, the fin member 9 extending from the attachment base 8 at a 90° angle. The cross-section is T-shaped, and the cooling fins 9 are arranged in the middle of the attachment base 8. The length of the cooling fins 9 is greater than the width of the attachment base 8. The cooling fins 9 can be, for example, longer, preferably 1.1-1.5 times, or even longer if the surrounding geometry allows.

[0028] Figure 5 An embodiment of a T-shaped cooling fin 7 is shown, wherein the surface 21 of the fin component 9 exhibits a profile 22 for increasing the surface area and thus the heat dissipation area. The profile 22 is wavy and includes multiple recesses 23, which are rounded in this example. Of course, groove-shaped recesses can also be used. With such a profile design, the surface area of ​​each surface side 21 can be significantly increased.

[0029] Figure 6 Another embodiment of the cooling fin 7 is shown. This cooling fin 7 has an L-shaped cross-section and also includes an attachment base 8 and a fin member 9 extending at a 90° angle. This cooling fin 7 can also be configured with... Figure 3 The same method is used, except that only one row of fastening screws 16 is provided.

[0030] at last, Figure 7A wind turbine 24 of the present invention is shown, comprising a tower 25 and a nacelle 26 attached to the tower 25. A rotor 1 of a generator 2 is connected to a hub 26, and a plurality of rotor blades 27 are attached to the hub 26. When wind blows, the wind interacts with the rotor blades 27, thereby rotating the hub 26, which in turn rotates the rotor 1. The rotor 1 rotates about a stationary stator 3, causing the generator 2 to generate its electricity, as is known. As shown, cooling fins 7 of the rotor 1 extend into the surrounding space, through which air flows, and heat from the heated magnetic element 18 is transferred to this surrounding space.

[0031] Although the invention has been described in detail with reference to preferred embodiments, the invention is not limited to the disclosed examples, and those skilled in the art can derive other variations from the disclosed examples without departing from the scope of the invention.

[0032] Individuals who are male or female are also included in the term, independent of the use of grammatical terms.

Claims

1. A wind turbine generator comprising an inner stator (3) and an outer rotor (1), said outer rotor (1) comprising a cylindrical rotor yoke (4), wherein a plurality of cooling elements (6) are attached to the outer surface of said rotor yoke (4), characterized in that The cooling element (7) is a cooling fin (7), which includes a plate-shaped attachment base (8) attached to the outside of the rotor yoke (4) and a fin member (9) extending at an angle from the attachment base (8).

2. The wind turbine generator according to claim 1, characterized in that, The plate-shaped fin component (9) extends from the attachment base (8) at an angle of 45°-135°, preferably 60°-120°, and especially 90°.

3. The wind turbine generator according to claim 1 or 2, characterized in that, The cooling fins (7) have a T-shaped or L-shaped cross section.

4. The wind turbine generator according to any one of the preceding claims, characterized in that, The length of the fin component (9) in the radial direction is greater than the width of the attachment base (8) in the circumferential direction.

5. The wind turbine generator according to any one of the preceding claims, characterized in that, The fin component (9) is provided with an enlarged surface profile (22).

6. The wind turbine generator according to any one of the preceding claims, characterized in that, The cooling fins (7) extend parallel to or at an angle to the axis of rotation of the rotor (1) and extend over at least half the length of the rotor yoke (4).

7. The wind turbine generator according to any one of the preceding claims, characterized in that, The outer surface (5) is provided with a recess (11) having a flat and planar bottom (13) and the attachment base (8) is accommodated in the recess (11).

8. The wind turbine generator according to any one of the preceding claims, characterized in that, An intermediate heat transfer layer (13) is provided between the outer surface (5) and the attachment base (8).

9. The wind turbine generator according to claim 8, characterized in that, The heat transfer layer (13) is a thermal paste or a polymer-based foil or plate or thermal pad.

10. A wind turbine generator according to any one of the preceding claims, characterized in that... The attachment base (8) is fixed to the rotor yoke (4) by means of a screw (16) screwed into a threaded blind hole (14) provided in the rotor yoke (4), or the attachment base (8) is fixed to the rotor yoke (4) by welding, or the attachment base is fixed by gluing.

11. A wind turbine generator according to any one of the preceding claims, characterized in that... The sealing device (17) is disposed in the transition area from the attachment base (8) to the outer surface (5) and / or in the transition area from the screw (16) to the attachment base (8).

12. The wind turbine generator according to any one of the preceding claims, characterized in that, The rotor yoke (4) has a plurality of magnet elements (18) on its inner side (20), wherein the number of cooling fins (7) is at least half the number of magnet elements (18).

13. The wind turbine generator according to claim 12, characterized in that, At least some of the cooling fins (7) are arranged to be radially flush with the magnet element (18).

14. The wind turbine generator according to any one of the preceding claims, characterized in that, The cooling fins (7) are made of aluminum, preferably corrosion-resistant aluminum.

15. A wind turbine comprising a wind turbine generator (2) according to any one of the preceding claims.

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