Cooling of active elements of electrical machines

Abstract

To provide methods for cooling electrical machines.SOLUTION: The present disclosure relates to electrical machines, cooling systems and methods for cooling active elements of the electrical machines. More specifically, the present disclosure relates to cooling systems and methods for cooling active rotor elements and / or active stator elements of a generator of a wind turbine, e.g. of a direct drive wind turbine. A cooling method comprises supplying a cooling fluid to an air gap through one or more primary inlets of an electrical machine for cooling a plurality of active elements of a rotor of the electrical machine and / or a plurality of active elements of a stator of the electrical machine separated by the air gap. The method further comprises reversing a direction of the flow of the cooling fluid such that the cooling fluid is extracted from the electrical machine through one or more primary inlets.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an electromechanical machine, a cooling system, and a method for cooling an active element of an electromechanical machine. More specifically, the present disclosure relates to a cooling system and method for cooling an active rotor element and / or an active stator element of a generator of a wind turbine, such as a direct drive wind turbine.

Background Art

[0002] Electromechanical machines such as motors and generators generally comprise a rotor structure and a stator structure. A large generator may be, for example, an electrically excited generator or a permanent magnet excited generator (PMG). The rotor of an electromechanical machine rotates with respect to the stator. The rotor may be an inner structure and the stator may be an outer structure. Thus, in this case, the stator surrounds the rotor, for example, in the radial direction. Alternatively, the configuration may be opposite, i.e., the rotor surrounds the stator, for example, in the radial direction.

[0003] Such a generator can be used, for example, in a wind turbine. A wind turbine generally comprises a rotor having a rotor hub and a plurality of blades. The rotor is configured to rotate under the influence of wind on the blades. The rotation of the rotor shaft directly drives ("direct drive") the generator rotor or drives it using a gearbox.

[0004] A direct drive wind turbine generator can have, for example, a diameter of 6 to 10 meters (236 to 328 inches), for example, a length of 2 to 3 meters (79 to 118 inches), and can rotate at a low speed, for example, in the range of 2 to 20 rpm (revolutions per minute). Alternatively, the generator may also be coupled to a gearbox that increases the rotational speed of the generator, for example, to 50 to 500 rpm or more.

[0005] Cooling is generally important in electrical machinery such as generators for direct-drive wind turbines. In particular, active elements of the rotor and stator, such as permanent magnets and coils, can generate heat. Rising temperatures of active rotor and stator elements can lead to failure of the active elements and reduce the efficiency of the generator. To lower the temperature of the active elements of the rotor and stator, a cooling fluid may be flowed through an air gap that isolates the active elements. The cooling fluid comes into contact with the active elements and removes heat from them. A cooling system can be provided to guide the cooling fluid toward and away from the air gap, and thus remove heat from the active elements of the rotor and stator.

[0006] Such a cooling system may include a primary or "main" path or loop. The main loop may include a fluid inlet for the main fluid. The main fluid may be carried from the main fluid inlet to the active rotor and active stator elements. For example, air can be introduced into the air gap between the active rotor and active stator elements. During operation, the active elements generate heat, and the cooling fluid (which may be air) is also heated. The heated main fluid can then be carried away to the main fluid outlet. In some examples, the main fluid outlet and inlet may be in fluid communication with the air outside the wind turbine, for example, surrounding the nacelle. For example, the cooling system may include a fan, for example, in the nacelle, for introducing air from outside the wind turbine through the main fluid inlet. A conduit can carry the main loop fluid from the main fluid inlet to the generator air gap, and the conduit can then carry the heated main cooling fluid from the generator air gap to the fluid outlet.

[0007] In other examples, the main fluid inlet and main fluid outlet may be in fluid communication with the heat exchanger. A secondary path or loop for the cooling fluid may include a heat exchanger. The heat exchanger may comprise a heat exchanger main cooling fluid inlet, a heat exchanger main cooling fluid outlet, a heat exchanger secondary fluid inlet, and a heat exchanger secondary fluid outlet. The main cooling fluid heated in the air gap of the generator (i.e., the fluid used for the cooling elements in the air gap, commonly referred to herein as the “cooling fluid”) may be led to the heat exchanger through the heat exchanger main cooling fluid inlet. The secondary fluid (i.e., the fluid used to cool the main cooling fluid or “cooling fluid”, rather than directly cooling the elements in the air gap) may be led to the heat exchanger through the heat exchanger secondary fluid inlet. The secondary fluid can cool the main cooling fluid. The secondary fluid may be removed from the heat exchanger through the heat exchanger secondary outlet, and the main fluid may be removed from the heat exchanger through the heat exchanger main outlet. The secondary fluid may be, for example, water or air. Using conduits, the heated main cooling fluid can be guided into the heat exchanger, and after cooling, the fluid can be discharged from the heat exchanger. The cooled main cooling fluid can then be guided again towards the air gap between the rotor's active element and the stator's active element. [Overview of the project]

[0008] One aspect of the present disclosure provides a method for cooling an electromachine. The electromachine comprises a rotor including a plurality of active rotor elements, a stator including a plurality of active stator elements, and an air gap separating the active rotor elements from the active stator elements. The method includes supplying a cooling fluid to the air gap through one or more primary inlets of the electromachine to cool the plurality of active elements of the rotor and / or the plurality of active elements of the stator. The method further includes reversing the direction of the flow of the cooling fluid so that the cooling fluid is extracted from the electromachine through one or more of the primary inlets.

[0009] According to this embodiment, a cooling fluid can be supplied to the air gap in a first direction for a certain period of time, and then the cooling fluid can be supplied to the air gap in a second direction different from the first direction, for example, the opposite direction. Switching the direction of the cooling fluid flow changes the heat distribution within the air gap. When the cooling fluid is supplied in the first direction, active elements that first come into contact with the cooling fluid are cooled more than active elements that later come into contact with the cooling fluid, whose temperature has already risen. When the cooling fluid is supplied in a second, for example, opposite direction, active elements that previously received the least cooling may now be cooled more because they may be colder when the cooling fluid comes into contact with them. Similarly, active elements that previously received the most cooling may not be cooled as much this time because they may be heated by the time the cooling fluid reaches them.

[0010] By reversing the direction of the cooling flow, the heat load can be better distributed among the active elements and / or the period during which the active elements are maintained at relatively high temperatures can be shortened, thus extending, and even eliminating (within the expected lifespan of the electrical machinery) the failure of active elements, such as the failure of the insulator surrounding the active elements. Therefore, the service life of the electrical machinery can be extended and the need for repairs can be reduced. The lifespan of the insulator of the active elements can be extended by about 50% or even 100%. For example, the service life of the insulator of the coil for the stator of a generator, such as for a direct-drive wind turbine, can be extended from about 25 years to about 50 years in some cases.

[0011] Furthermore, when the rotor of an electromechanical device rotates during use, switching the direction of the cooling fluid allows not only to change the heat distribution in the direction in which the cooling fluid is supplied to the air gap, for example, in the axial direction, but also to change the heat distribution in the circumferential direction. Therefore, the temperature of the active element can be changed in the direction in which the cooling fluid is supplied to the air gap, for example, in the axial and circumferential directions. This can further contribute to improving the service life of the active rotor element and / or active stator element.

[0012] Furthermore, reversing the direction of the cooling fluid alters the temperature distribution of the active element, and therefore the location of the hot spot also changes. This reduces the time the active element can withstand higher temperatures, allowing it to withstand higher temperatures. This, in turn, increases the output of the electromechanical unit.

[0013] Through this disclosure, the primary inlet (outlet) of an electromachine can be understood as the inlet (outlet from the electromachine) point for the cooling fluid into the electromachine in a first operating mode. In a second operating mode, the primary inlet (outlet) can be the outlet (inlet) point of the electromachine for the cooling fluid.

[0014] Active elements used throughout this disclosure can be considered as magnetically and / or electrically active rotor and / or stator elements. Active stator elements may be, for example, one or more permanent magnets, one or more permanent magnet modules, one or more coils, or one or more coil modules. Active rotor elements may similarly be one or more permanent magnets, one or more permanent magnet modules, one or more coils, or one or more coil modules. For example, an active stator element may be a coil, and an active rotor element may be a permanent magnet module. In other examples, both the active stator element and the active rotor element may be coils.

[0015] The electrical machinery may be a generator, particularly a generator for wind turbines, and more specifically, a generator for direct-drive wind turbines.

[0016] In yet another embodiment, an electromechanical assembly is provided. The electromechanical assembly comprises an electromachine and a cooling system fluidly connected to the electromachine. The electromachine comprises a rotor including a plurality of active rotor elements, a stator including a plurality of active stator elements, and an air gap separating the active rotor elements and the active stator elements. The cooling system comprises one or more inlet cooling conduits configured to guide a cooling fluid toward the air gap, and one or more outlet cooling conduits configured to collect the cooling fluid heated in the air gap and guide it away from the electromachine. The cooling system is configured to reverse the direction of the flow of the cooling fluid.

[0017] In yet another embodiment, a generator assembly is provided. The generator assembly comprises a generator and a cooling system fluidly connected to the generator. The generator comprises a rotor including a plurality of active rotor elements, a stator including a plurality of active stator elements, and an air gap separating the active rotor elements from the active stator elements. The cooling system comprises a plurality of conduits configured to guide a cooling fluid toward the air gap and away from the generator. The cooling system is configured to guide the cooling fluid in a first direction and a second direction different from the first direction such that the cooling fluid flows through the air gap in two different directions. [Brief explanation of the drawing]

[0018] [Figure 1] This diagram schematically shows a perspective view of one embodiment of a wind turbine. [Figure 2] This figure shows an example of a wind turbine hub and nacelle. [Figure 3] This diagram schematically shows a flowchart of one embodiment of a method for cooling active rotor elements and active stator elements. [Figure 4A] This diagram schematically shows a cross-section of an embodiment of an electromachine in which a cooling fluid flows through an air gap in two different directions. [Figure 4B]FIG. is a schematic cross-sectional view of an embodiment of an electric machine in which a cooling fluid flows in two different directions through an air gap. [Figure 5A] FIG. schematically shows a side view of an electric machine fluidly connected to a cooling system according to two embodiments. [Figure 5B] FIG. schematically shows a side view of an electric machine fluidly connected to a cooling system according to two embodiments. [Figure 6A] FIG. schematically shows a side view of an electric machine fluidly connected to a cooling system according to another embodiment. [Figure 6B] FIG. schematically shows a side view of an electric machine fluidly connected to a cooling system according to another embodiment. [Figure 7A] FIG. schematically shows the change in temperature of an active rotor element or an active stator element as a function of time and in response to the setting of a temperature threshold. [Figure 7B] FIG. schematically shows the change in temperature of an active rotor element or an active stator element as a function of time and in response to the setting of a temperature threshold. DETAILED DESCRIPTION OF THE INVENTION

[0019] Reference will now be made in detail to embodiments of the present invention, in which one or more examples are illustrated in the drawings. Each example is presented as an illustration of the present invention, not a limitation. It will be apparent to those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment can be used in combination with another embodiment to yield further embodiments. Accordingly, the present invention is intended to embrace such modifications and changes that fall within the scope of the appended claims and their equivalents.

[0020] Although a generator for a direct drive wind turbine is mainly referred to herein, the present invention can generally be applied to electric machines.

[0021] FIG. 1 is a perspective view of an embodiment of a wind turbine 10. In this embodiment, 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 20 and extending outwardly from the hub 20. In this embodiment, the rotor 18 has three rotor blades 22. In alternative embodiments, the rotor 18 includes more or fewer than three rotor blades 22. The tower 15 can be made of tubular steel to define a cavity (not shown in FIG. 1) between the support system 14 and the nacelle 16. In alternative embodiments, the tower 15 is any suitable type of tower having any suitable height. According to an alternative form, the tower may be a hybrid tower comprising a concrete portion and a tubular steel portion. Also, the tower may be a partial or complete lattice tower. The wind turbine 10 can be installed both on land and offshore.

[0022] The rotor blades 22 may be spaced around the hub 20 to facilitate rotation of the rotor 18 and so that kinetic energy can be transferred from the wind to usable mechanical energy and subsequently to electrical energy. The rotor blades 22 are fitted to the hub 20 by coupling the blade root portion 24 to the hub 20 in a plurality of load transfer regions 26. The load transfer regions 26 may have hub load transfer regions and blade load transfer regions (both not shown in FIG. 1). Loads induced on the rotor blades 22 are transferred to the hub 20 via the load transfer regions 26.

[0023] In the embodiment, the rotor blades 22 can have lengths ranging from about 15 meters (m) to about 90 meters or more. The rotor blades 22 may have any suitable length that allows the wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include lengths of 20 m or less, 37 m, 48.7 m, 50.2 m, 52.2 m, or more than 91 m. When wind strikes the rotor blades 22 from the wind direction 28, the rotor 18 rotates around the rotor axis 30. As the rotor blades 22 rotate and are subjected to centrifugal force, the rotor blades 22 are also subjected to various forces and moments. Thus, the rotor blades 22 can be deflected and / or rotated from a neutral or non-deflected position to a deflected position.

[0024] 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, is changed by the pitch system 32, and the load and power generated by the wind turbine 10 can be controlled 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 also shown. During the operation of the wind turbine 10, the pitch system 32 can specifically change the pitch angle of the rotor blades 22 so that the angle of attack of (part of) the rotor blades is reduced, thereby facilitating a reduction in rotational speed and / or facilitating a stall of the rotor 18.

[0025] In this embodiment, the blade pitch of each rotor blade 22 is individually controlled by the wind turbine controller 36 or the pitch control system 80. Alternatively, the blade pitch of all rotor blades 22 may be controlled simultaneously by the control system.

[0026] Furthermore, in this embodiment, as the wind direction 28 changes, the yaw direction of the nacelle 16 can be rotated around the yaw axis 38, thereby positioning the rotor blades 22 relative to the wind direction 28.

[0027] In this embodiment, the wind turbine controller 36 is shown as being concentrated within the nacelle 16, but the wind turbine controller 36 may be a distributed system located throughout the wind turbine 10, on the support system 14, within the wind power plant, and / or in a remote control center. The wind turbine controller 36 includes a processor 40 configured to perform the methods and / or steps described herein. Furthermore, many of the other components described herein include processors.

[0028] As used herein, the term “processor” is not limited to integrated circuits referred to as computers in the prior art, but broadly includes controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and / or control system may also include memory, input channels, and / or output channels.

[0029] 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. More specifically, the hub 20 of the rotor 18 is rotatably coupled to an electric generator 42 positioned 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 46, which then 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 an inverter can be placed in the nacelle 16 to convert the electrical energy generated by the generator 42, which has a voltage of 400V to 1000V, into electrical energy having a medium voltage (10 to 35kV). The electrical energy is then conducted from the nacelle 16 to the tower 15 via power cables.

[0030] The gearbox 46, generator 42, and transformer 90 may be supported by the main support structure frame of the nacelle 16, or optionally embodied as the 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 this embodiment, the nacelle 16 also includes a main front support bearing 60 and a main rear support bearing 62. Furthermore, the generator 42 may be mounted to the main frame 52 by isolation support means 54, in particular to prevent vibrations of the generator 42 from being introduced into the main frame 52 and thereby causing a noise emission source.

[0031] Optionally, the main frame 52 is configured to bear the weight of the components of the rotor 18 and nacelle 16, as well as the entire load caused by the wind and rotational load, and further 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 any associated fastening, support, and / or fixing devices, including but not limited to support 52, front support bearing 60, and rear support bearing 62, may be referred to as the drivetrain 64.

[0032] In some embodiments, 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 in the direct-drive wind turbine. Therefore, the generator 42 generally has a much larger diameter than the generator used in a wind turbine with a gearbox 46 in order to provide the same amount of power as a wind turbine with a gearbox.

[0033] The nacelle 16 may also include a yaw drive mechanism 56 that can be used to rotate the nacelle 16 and, consequently, the rotor 18 around the yaw axis 38, thereby controlling the viewpoint of the rotor blades 22 with respect to the wind direction 28.

[0034] To properly position the nacelle 16 with respect to the wind direction 28, the nacelle 16 may also include at least one meteorological measurement system which may include a wind vane and an anemometer. The meteorological measurement system 58 can provide the wind turbine controller 36 with information which may include wind direction 28 and / or wind speed. In this embodiment, the pitch system 32 is at least partially located within the hub 20 as a pitch assembly 66. 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. Only one of the three pitch drive systems 68 is shown in Figure 2.

[0035] In this embodiment, 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 a 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 rotation of the pitch drive pinion 78 causes the rotation of the pitch bearing 72.

[0036] The pitch drive system 68 is coupled to the wind turbine controller 36 to adjust the pitch angle of the rotor blades 22 upon receiving one or more signals from the wind turbine controller 36. In this embodiment, the pitch drive motor 74 is any suitable motor driven by a power and / or hydraulic system that enables the pitch assembly 66 to function as described herein. Alternatively, the pitch assembly 66 may include any suitable structure, configuration, arrangement, and / or components, but is not limited to, hydraulic cylinders, springs, and / or servo mechanisms. 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.

[0037] The pitch assembly 66 may also include one or more pitch control systems 80 for controlling the pitch drive system 68 in accordance with control signals from the wind turbine controller 36 in certain priority situations and / or during rotor overspeed. In this embodiment, 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 embodiment, 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 can control the pitch drive system 68 to adjust the pitch angle of the rotor blades 22.

[0038] According to one embodiment, for example, a power generator 84 comprising a battery and an electric capacitor is located in or within the hub 20 and coupled to the sensor 70, the pitch control system 80, and the pitch drive system 68 to provide a power source to these components. In this embodiment, the power generator 84 provides a continuous power source to the pitch assembly 66 during the operation of the wind turbine 10. In an alternative embodiment, the power generator 84 provides power to the pitch assembly 66 only during power loss events of the wind turbine 10. Power loss events may include power grid loss or degrading, malfunction of the wind turbine 10's electrical system, and / or failure of the wind turbine controller 36. During a power loss event, the power generator 84 operates to provide power to the pitch assembly 66 so that the pitch assembly 66 can operate during the power loss event.

[0039] In this embodiment, the pitch drive system 68, sensor 70, pitch control system 80, cable, and power generator 84 are each positioned within a cavity 86 defined by the inner surface 88 of the hub 20. In an alternative embodiment, the components may be positioned relative to the outer surface of the hub 20 and coupled directly or indirectly to the outer surface.

[0040] One aspect of the present disclosure provides a method 100 for cooling an electromachine 200. This method is shown in Figure 3. The electromachine 200 comprises a rotor 210 including a plurality of active rotor elements 212, a stator 220 including a plurality of active stator elements 222, and an air gap 215 separating the active rotor elements 212 and the active stator elements 222.

[0041] The method includes, in block 110, supplying a cooling fluid 140 to the air gap 215 through one or more primary inlets 236, 256 of the electromachine 200 to cool the multiple active elements 212 of the rotor 210 of the electromachine 200 and / or the multiple active elements 222 of the stator 220 of the electromachine 200, which are separated by the air gap 215.

[0042] The electrical machine 200 may be a generator for the wind turbine 10, for example, a generator for a direct-drive wind turbine. Figure 4A shows a cross-sectional view of one embodiment of the generator 200 comprising a rotor 210 and a stator 220. The rotor 210 is configured to rotate around a rotation axis 205. The rotor 210 comprises a rotor rim 211 and a plurality of active rotor elements 212 attached to the rotor rim 211. The stator 220 comprises a stator rim 221 and a plurality of active stator elements 222 attached to the stator rim 221.

[0043] The rotor 210 may include a drive-side cover 231 and a center-side cover 232. The drive-side cover 231, also called the front-side cover 231, may be configured to face the wind turbine hub 20. That is, the drive-side 234 of the generator can be defined as the side driven by the rotor of the wind turbine in this case. In the case of a motor, the drive-side of the motor can be defined as the side on which the motor drives the electric elements. The non-drive-side 235 of the generator may be opposite to the drive-side of the generator.

[0044] As seen in this embodiment, the drive-side cover 231 may extend mainly in the radial direction 240 and the tangential or circumferential direction 242. The drive-side cover 231 can protect the active elements of the rotor and stator from moisture and undesirable wind particles such as dust in the axial direction 241. The center-side cover 232 may include the rotor rim 211 and may extend mainly in the circumferential direction 242 and the axial direction 241. The rotor may further include a non-drive-side cover 233. The non-drive-side cover 233 may also be called the rear-side cover 233. The center-side cover 232 may extend between the drive-side cover 231 and the non-drive-side cover 233 of the rotor 210.

[0045] Similarly, the stator 220 may comprise a central plate 262 and a non-driven or rear plate 263. In some embodiments, the stator 220 may additionally comprise a driven or front plate (not shown). The stator 220 may be fixedly mounted to the generator support 203. The rotor 210 may be rotatably mounted to the generator support 203 and operably connected to the hub 20 or other components of the wind turbine rotor. The driven-side cover 231 of the rotor 210 may be supported by the generator support 203 via a bearing 201. If the rotor 210 comprises a non-driven-side cover 233 extending to the generator support 203, a bearing may also be used to join the non-driven-side cover 233 to the support 203. The generator support 203 may be the front portion of a wind turbine frame, such as a direct-driven wind turbine frame.

[0046] In this embodiment, the cooling system may be located on the non-driven side of the generator 200, for example, on the non-driven side cover 233. For example, an air extraction system and / or an air supply system may be located on the non-driven side 235 of the generator. In this embodiment, it can be seen that the non-driven side cover 233 extends radially inward but does not extend completely to contact the generator support 203. Cooling air conduits for supplying and extracting a cooling fluid, such as air, may be located in the radial space 237 provided between the cover 233 and the generator support 203. Primary inlets 236 and primary outlets 256 may be located in the space 237 between the non-driven side cover 233 of the rotor and the generator support 203.

[0047] In this embodiment, the air gap 215 is a radial air gap and the generator 200 is a radial generator; however, in other embodiments, the generator 200 may be an axial generator having an axial air gap. In Figure 3, the rotor 210 surrounds the stator 220. In other embodiments, the stator may surround the rotor.

[0048] Figure 4A schematically shows that the active rotor element 212 and / or active stator element 222 can be cooled by supplying the cooling fluid 140 to the air gap 215 in a first direction 150. The cooling fluid 140 may be introduced into the generator 200, for example, through the primary inlet 236 of the rear cover 233 of the rotor 210, then guided through the stator 220 toward the front cover 231 of the rotor, and then led toward the air gap 215. The shape of the stator and rotor may already serve the function of guiding the cooling fluid 140 through the generator 200, or one or more conduits may be used to guide the cooling fluid 140 through the generator.

[0049] In this embodiment, the cooling fluid 140 first comes into contact with the active elements 212, 222 in or near the drive side or front region 160 of the generator, and if the active elements are hot, the temperature of the cooling fluid rises. The cooling fluid 140 then moves toward the rear cover 233 of the rotor. By the time it reaches the active elements 212, 222 in the non-drive side or rear region 165 of the generator, the cooling fluid 140 is already warm, so the temperature of the active elements in the rear region 165 may not drop as much as the temperature of the active elements in the front region 160. Therefore, hot spots may be generated in the rear region 165, and the active elements in this region 165 may be at a higher risk of overheating and failure than the active elements in the front region 160. The heated cooling fluid 140 can then be discharged through the primary outlet 256 of the rear cover 233 of the rotor 210.

[0050] In Figures 4A and 4B, the primary inlet 236 and primary outlet 256 of the generator for the cooling fluid 140 are shown aligned along the radial direction 240. This is merely illustrative, and it should be noted that the primary inlet 236, from which the cooling fluid can be introduced into the generator 200, and the primary outlet 256, from which the cooling fluid can be discharged, do not necessarily have to be aligned along the radial direction 240. For example, the primary inlet 236 and primary outlet 256 of the cooling fluid 140 may be displaced along the circumferential direction 242. Alternatively, the primary inlet and primary outlet may be provided in the gap 237. For example, a conduit could guide the cooling fluid 140 through the space 237 toward the inside of the generator 200 at a first circumferential position, and another conduit could guide the heated cooling fluid 140 away from the generator through the gap 237 at a second circumferential position.

[0051] The method in Figure 3 further includes the step of reversing the direction of the flow of the cooling fluid 140 in block 120 so that the cooling fluid 140 is extracted from the electromachine 200 through one or more of the primary inlets 236, for example, all of them.

[0052] Figure 4B schematically illustrates this. The cooling fluid 140 enters the generator 200 through the primary outlet 256 of the rear cover 233 of the rotor 210 and is guided toward the air gap 215. Thus, the primary inlet 236 of the rotor or generator in Figure 4A becomes the outlet 236 in Figure 4B, and therefore the primary outlet 256 of the rotor or generator in Figure 4A becomes the inlet 256 of the operating mode in Figure 4B. With the direction of flow reversed, the cooling fluid now first contacts the active elements 212, 222 in the rear region 165, then heats up as it moves axially through the air gap, and then contacts the active elements in the front region 160. In this operation, the active elements in the rear region 165 can be cooled more than the active elements in the front region 160. Therefore, hot spots are more likely to form in the front region 160.

[0053] As the rotor 210 rotates, the temperature distribution of the active elements and the air gap 215 can become non-uniform, even along the circumferential direction 242. Reversal of the cooling flow can also affect cooling along the circumferential direction 242. Therefore, which active elements 212, 222 are cooled more and which are not can be varied along the entire air gap, i.e., both axially oriented 241 and circumferentially oriented 242. Since the active elements 212, 222 with the highest temperature change due to the reversal of the cooling fluid flow, failures due to overheating can be reduced and, in some cases, avoided. The need for repairs can also be reduced. For example, the need to replace the insulators of the active elements, such as electrical insulators, can be eliminated. Furthermore, since hot spots will not always be located in the same place, the active elements 212, 222 can withstand higher temperatures, and the power generated by the generator 200 can be increased. Therefore, depending on the requirements of the electromechanical device 200, an appropriate combination of extending the achievable lifespan of the active elements 212, 222 and their insulators and increasing power output can be achieved.

[0054] Any suitable cooling fluid 140 may be used, and in particular, various cooling gases may be used. In some embodiments, air is used as the cooling fluid.

[0055] The time for which the cooling fluid 140 is supplied in a particular direction may be substantially equal to or different from the time for which the cooling fluid 140 is supplied in another direction. During the first period, the cooling fluid 140 may be supplied through the air gap 215 from one or more primary inlets 236 of the electromachine 200 to one or more primary outlets 256 of the electromachine 200. During the second period, the cooling fluid 140 may be supplied through the air gap 215 from one or more primary outlets 256 to one or more primary inlets 236. In some embodiments, the second period may be substantially equal to the first period. In other embodiments, the second period may be different from the first period.

[0056] As shown in the embodiment of Figure 4A, the cooling fluid 140 may be supplied to the air gap 215 in a first direction 150 during the first period. As shown in the embodiment of Figure 4B, the cooling fluid 140 may be supplied to the air gap 215 in a second direction 155 during the second period. The second direction 155 may be opposite to the first direction 150. In some embodiments, the first direction 150 and the second direction 155 may be substantially axial 241.

[0057] Reversing the direction of the cooling fluid 140 can be performed in several ways. For example, if one or more fluid displacement devices 310 are used to flow the cooling fluid toward the air gap 215 to cool the active elements, or to assist the flow of the cooling fluid, the reversing step 120 may include reversing the direction of rotation of one or more fluid displacement devices 310, for example, one or more rotating elements within the fluid displacement device. The fluid displacement device 310 is configured to drive the cooling fluid 140 in a particular direction, for example, by creating a pressure difference between two points in the path of the cooling fluid, and thus creating a low-pressure region through which the cooling fluid flows. The fluid displacement device 310 may be, for example, a pump or a fan. Reversing the direction of rotation of the fluid displacement device 310 may be performed during maintenance or repair work on the wind turbine 10. For example, reversing the direction of rotation may be performed manually when the motor of the fluid displacement device is replaced.

[0058] One or more cooling fluid displacement devices 310 may include one or more impellers. The reversing step 120 may include switching the rotation direction of one or more impellers. In some embodiments, the impellers may be bidirectional. The motor(s) of the fluid displacement device 310 may be configured to rotate the bidirectional impellers in two opposite directions.

[0059] Figures 5A and 5B schematically show side views of two embodiments of a cooling system 300 fluidly connected to an electromachine 200. In Figure 5A, an inlet conduit 320 is configured to carry cooling fluid 140 to the generator 200, and an outlet conduit 330 is configured to carry the heated cooling fluid 140 away from the generator 200. One or more filters may be placed inside the conduits to conditioned the air. The inlet conduit 320 and outlet conduit 330 may be fluidly connected to the generator 200 outside the nacelle 16, for example. Each conduit 320, 330 has an inlet and an outlet. One or more cooling fluid propulsion devices 310, for example, one or more fans, are configured to move the cooling fluid 140 through the conduits 320, 330, for example, through the inlet conduit 320 toward the generator 200, and through the outlet conduit 330 toward the generator 200. One or more cooling fluid propulsion devices 310 are configured to reverse the direction of rotation of the cooling fluid 140, causing the cooling fluid 140 to move in the opposite direction. For example, the rotation of one or more fan impellers can be reversed. Thus, the outlet conduit 330 becomes the inlet conduit, and the inlet conduit 320 becomes the outlet conduit.

[0060] One or more cooling fluid displacement devices 310 may be arranged with the inlet conduit 320 and / or outlet conduit 330. The fluid displacement devices 310 may be located at any suitable position along the conduits 320, 330, for example, inside the conduits 320, 330. Depending on the type of fluid displacement device 310, the fluid displacement device may be located outside the conduit but in fluid contact with the conduit. It should be noted that the “inlet” point 236 to the electromachine and the “outlet” point 256 from the electromachine may depend on the direction of flow and therefore change over time depending on the configuration of the cooling cycle. Thus, the primary inlet (for the first or primary cooling flow direction) may become the outlet in the second cooling flow direction.

[0061] In Figure 5B, the cooling system 300 includes a heat exchanger 315 equipped with one or more heat exchanger fluid displacement devices 310', which drives a heat exchanger cooling fluid 145 through the heat exchanger 315 to cool the primary cooling fluid 140. In this specification, the cooling fluid 140 flowing through the air gap 215 may be referred to as the primary cooling fluid, and the cooling fluid 145 flowing through the heat exchanger 315 to cool the primary cooling fluid 140 may be referred to as the secondary cooling fluid. The heat exchanger may include a secondary heat exchanger inlet and a secondary heat exchanger outlet, respectively, for introducing the secondary cooling fluid into and removing it from the heat exchanger 315. The heat exchanger further includes a primary heat exchanger inlet and a primary heat exchanger outlet, respectively, for introducing the primary cooling fluid 140 into and removing it from the heat exchanger 315.

[0062] In some embodiments, the heat exchanger 315 may be equipped with one or more main fluid displacement devices 310. That is, instead of arranging one or more main fluid displacement devices 310 outside the heat exchanger 315, or in addition to that, the main fluid displacement devices 310 may be arranged, for example, inside the heat exchanger 315. In some of these embodiments, the direction of the main cooling fluid 140 can be switched by reversing the direction of rotation of the fluid displacement devices 310, for example, of a rotating element 310, for example, of an impeller 310 inside the heat exchanger 315.

[0063] Similar to the cooling fluid displacement device 310, in some embodiments, one or more heat exchanger fluid displacement devices 310' may be pumps or fans. For example, a fluid displacement device 310' for a rotating element(s), such as an impeller(s) inside it, can be used to reverse the direction of rotation and switch the direction of the secondary cooling fluid 145.

[0064] In other embodiments, the reversing step 120 may include fluidly connecting one or more inlet cooling conduits 320 for guiding the cooling fluid 140 toward the air gap 215 to one or more outlet cooling conduits 330 for guiding the cooling fluid 140 toward the air gap 215, thereby reversing the direction of flow of the cooling fluid 140.

[0065] That is, when the cooling fluid 140 is supplied in the first direction 150, the inlet cooling conduit 320 and the outlet cooling conduit 330 do not have to be directly (i.e., without the electromechanical unit 200 or the heat exchanger 315, if present) and fluidly connected. The inlet conduit 320 merely guides the cooling fluid 140 toward the air gap 215, and the outlet conduit 330 merely guides the heated cooling fluid 140 away from the air gap 215. For step 120 of reversing the direction of flow of the cooling fluid 140, the passage of the cooling fluid 140 through an additional conduit 340 configured to fluidly connect the inlet conduit 320 and the outlet conduit 330 may be permitted.

[0066] Figures 6A and 6B schematically show side views of an electromachinery 200, such as a generator for a direct-drive wind turbine 10, and a cooling system 300 fluidly connected to the electromachinery 200. The cooling system 300 may be provided, for example, within the nacelle 16. The cooling system 300 comprises one or more inlet conduits 320 and one or more outlet conduits 330. A cooling fluid 140, such as air, may flow through one or more inlet conduits 320 toward the air gap 215, its temperature rises, and then be collected by one or more outlet conduits 330 and flow through one or more outlet conduits 330. As seen in Figures 5A to 6B, the cooling fluid 140 can be introduced into the generator 200 at a specific circumferential position and collected at another circumferential position.

[0067] The additional conduit 340 may optionally fluidly connect one or more inlet conduits 320 to one or more outlet conduits 330. Thus, the direction of flow of the cooling fluid 140 can be reversed. The additional conduit 340 may be closed, as shown in Figure 6A, while the cooling fluid 140 is supplied to the air gap 215 in the first direction 150.

[0068] The flow of the cooling fluid 140 can be redirected by opening an additional cooling conduit 340. For example, the reversal step 120 may include operating a number of valves 350 to redirect the cooling fluid 140 through the additional cooling conduit 340 and reverse the direction of its flow. As shown in Figure 6B, the valves 350 were operated to change the path of the cooling fluid 140. Some valves 350 were operated to close parts of the inlet conduit 320 and outlet conduit 330, and some valves 350 were operated to allow passage through the additional conduit 340. In some embodiments, the valves 350 may be electrically operated, for example, by an electric motor.

[0069] In this way, the cooling fluid can be introduced to the generator 200 at a first circumferential position when the cooling fluid 140 circulates in a first direction and collected at a second circumferential position (Figure 6A), and the cooling fluid can be introduced to the generator at a second circumferential position and collected at the first circumferential position when the direction of the cooling fluid flow is reversed (Figure 6B). As shown in these figures, the first and second circumferential positions may be different. The trajectories of the cooling fluid into and out of the air gap may also be different from these different circumferential positions, for example, as shown with reference to Figure 4. In particular, how the cooling fluid traverses the air gap axially may depend on whether the cooling fluid is supplied according to Figure 6A or according to Figure 6B.

[0070] The cooling conduits 320 and 330 in Figures 6A and 6B may be fluidly connected to the ambient air surrounding the nacelle 16, as described with respect to Figure 5A, or they may be fluidly connected to the heat exchanger 315, as described with respect to Figure 5B.

[0071] Although Figures 5A to 6B show only one inlet conduit 320 and one outlet conduit 330, it should be noted that multiple inlet conduits 320 and multiple outlet conduits 330 may be provided. For example, four inlet conduits 320 configured to transport cooling fluid to different circumferential parts of the generator 200 and four outlet conduits 330 configured to carry away the cooling fluid from different circumferential parts of the generator 200 may be provided.

[0072] Step 120, which reverses the direction of the cooling fluid 140, may be performed at least once during the life of the generator 200. In some embodiments, the reversal step 120 may be performed only once during the expected service life of the generator 200. Even if the cooling fluid is reversed only once throughout the life of the electromachine, its performance and / or technical durability can be improved. Such a single reversal may be performed, for example, during planned (major) maintenance. In some other embodiments, the reversal 120 may be performed two or more times during the expected service life of the generator 200.

[0073] In some embodiments, the temperatures of several active elements 212, 222 may be monitored. For example, the temperatures of active stator elements such as coils and / or the insulators of the coils may be tracked. A temperature threshold can be set, and when the temperature of one or more active elements 212, 222 of the generator 200 reaches the temperature threshold, a reversal 120 may be performed. Reversing the direction of the cooling fluid when the threshold is reached may help to better control the temperature distribution along the active elements and the air gap 215. In general, the temperatures of one or more active stator elements and / or one or more active rotor elements may be monitored. For example, the temperatures of multiple stator elements may be tracked.

[0074] In some embodiments, a controller and one or more temperature sensors may be provided. The controller may be connected to one or more temperature sensors, for example, two or more temperature sensors. The controller may also be connected to one or more propellers 310, 310', such as multiple fans, and / or one or more valves 350, such as multiple valves. When the temperature of the active element (or its insulator) reaches a predetermined threshold, the controller can instruct one or more propellers 310, 310' to switch the direction of rotation, or one or more valves 350 to open or close (for example, to open if closed, or to close if open).

[0075] In some embodiments, the predetermined threshold may be the maximum temperature achievable by the active elements 212, 222 during use, taking into account possible safety margins. During use, the temperature of the active elements 212, 222 or their insulators may rise to reach the maximum temperature. If the active elements remain at such a temperature for an extended period, they may fail. Therefore, by reversing the direction of the cooling fluid when such a temperature is reached, the active elements can be cooled and the thermal stress on the active elements can be reduced.

[0076] In some other embodiments, the given threshold may be a temperature lower than the maximum achievable temperature during use. Embodiments of both situations are schematically shown in Figure 7A. This figure shows the temperature T of an active element, such as a coil or coil insulator, as a function of time t. AE This is a schematic representation. The solid line 381 represents the case where the reversal of the cooling fluid direction 120 is not performed. Therefore, the temperature of the active element only rises until it reaches a plateau. The dashed line 382 represents the change in temperature of the active element or its insulator when the threshold corresponds to the maximum achievable temperature 360 ​​and the reversal 120 is performed when this threshold is reached. Finally, the dotted line 383 represents the temperature of the active element or its insulator when a temperature threshold 365 lower than threshold 360 is set. Thresholds 360 and 365 are sometimes called upper temperature thresholds.

[0077] A predetermined lower temperature threshold 370 may also be set, and the inversion 120 may be performed when the higher temperature thresholds 360, 365 are reached, and when the lower temperature threshold 370 is reached. Thus, the temperature of the active element can be maintained within a specific temperature range enclosed by the upper and lower temperature thresholds.

[0078] In some embodiments, instead of step 120 in which the flow direction of the cooling fluid 140 is reversed when the threshold temperature 360 ​​is reached, the reversal 120 may be performed for a specific period 380 after the threshold temperature 360 ​​is reached. This option is schematically shown in Figure 7B.

[0079] In some embodiments, a temperature threshold may be set for a group of active elements. For example, instead of step 120 in which the flow of the cooling fluid 140 is reversed when the threshold temperature is reached by one active element, the flow may be reversed when two or more active elements reach the threshold. Alternatively, an average temperature threshold may be set for a group of active elements, for example, the temperature of two or more active elements may be monitored, and when the average temperature of two or more active elements reaches the threshold, an action is taken.

[0080] In a further aspect of the present disclosure, an electromechanical assembly 400 is provided. The electromechanical assembly comprises an electromachine 200 and a cooling system 300 fluidly connected to the electromachine 200. The electromachine 200 comprises a rotor 210 including a plurality of active rotor elements 212, a stator 220 including a plurality of active stator elements 222, and an air gap 215 separating the active rotor elements 212 and the active stator elements 222. The cooling system 300 comprises one or more inlet cooling conduits 320 for guiding a cooling fluid 140 toward the air gap 215, and one or more outlet cooling conduits 330 for collecting the cooling fluid 140 heated in the air gap 215 and guiding it away from the electromachine 200. The cooling system 300 is configured to reverse the direction of flow of the cooling fluid 140. Thus, the cooling fluid may be supplied to the air gap 215 in two different directions, such as two opposite directions.

[0081] The descriptions and explanations relating to Figures 3 to 7B can be applied to the cooling system 300 and the electromechanical unit 200.

[0082] The cooling system 300 may include one or more cooling fluid displacement devices 310, 310' configured to rotate in two opposite directions to reverse the direction of the cooling fluid flow. One or more fluid displacement devices may be arranged with one or more inlet conduits 320 and / or one or more outlet conduits 330. In some embodiments, the thrusters may be fans. The cooling fluid 140 may be air.

[0083] The cooling system 300 may include one or more additional conduits 340 configured to selectively fluidize one or more inlet conduits 320 and one or more outlet conduits 330 so as to reverse the direction of flow of the cooling fluid 140.

[0084] The cooling system 300 may include one or more valves 350 configured to act to redirect the flow of cooling fluid 140 through one or more additional conduits 340, as described with respect to Figures 6A and 6B. One or more valves 350 can regulate the passage of cooling fluid through one or more additional conduits 340 by allowing or obstructing the flow of cooling fluid through the additional conduits. The valves 350 may be opened or closed as needed.

[0085] The electromechanical assembly 400, for example, the electromechanism 200, may further include one or more temperature sensors configured to measure the temperature of one or more active elements 212, 222 or their insulators, as described with reference to Figures 7A and 7B. The assembly 400, for example, the cooling system 300, may include a controller configured to instruct the direction of the cooling fluid flow to be changed based on temperature readings from one or more temperature sensors. For example, the controller can instruct one or more thrusters 310 to change direction of rotation, or can instruct one or more valve actuators, for example, electric motors, to operate a valve 350 based on one or more readings from one or more temperature sensors.

[0086] The electromechanical unit 200 may be a generator for a wind turbine, more specifically for a direct-drive wind turbine. The electromechanical assembly 400 may be, for example, a generator assembly for a wind turbine, more specifically for a direct-drive wind turbine.

[0087] A wind turbine 10, in particular a direct-drive wind turbine equipped with a generator assembly 400, may be provided.

[0088] In a further aspect of the present disclosure, a generator assembly is provided. The generator assembly 400 comprises a generator 200 and a cooling system 300 fluidly connected to the generator 200. The generator 200 comprises a rotor 210 including a plurality of active rotor elements 212, a stator 220 including a plurality of active stator elements 222, and an air gap 215 separating the active rotor elements 212 and the active stator elements 222. The cooling system 300 comprises a plurality of conduits 320, 330, 340 configured to guide a cooling fluid 140 toward the air gap 215 and, after the cooling fluid 140 has passed through the air gap 215, toward the generator 200. The cooling system 300 is configured to selectively guide the cooling fluid 140 in a first direction and a second direction different from the first direction such that the cooling fluid 140 flows through the air gap 215 in two different directions.

[0089] The cooling system 300 may include one or more bidirectional fans 310, 310' configured to guide the cooling fluid 140 in first and second directions.

[0090] The cooling system 300 may further include a heat exchanger 315 fluid-connected to a plurality of conduits 320, 330 configured to guide the cooling fluid 140 toward and away from the air gap 215. One or more bidirectional fans 310, 310', including all fans, may be included in the heat exchanger 315. For example, one or more bidirectional fans for propelling the cooling fluid toward and away from the generator may be included in the heat exchanger 315.

[0091] The cooling system 300 may include a plurality of valves 350 configured to regulate the flow of the cooling fluid 140 through a plurality of conduits 320, 330, and 340 so that the cooling fluid 140 can flow in a first direction and a second direction.

[0092] A wind turbine 10, in particular a direct-drive wind turbine equipped with a generator assembly 400, may be provided.

[0093] The descriptions and explanations in Figures 3 to 7B can be applied to the cooling system 300 and the generator 200.

[0094] This specification discloses the present invention, including preferred embodiments, using examples, and enables a person skilled in the art to practice the invention, including by constructing and using any device or system and by performing any incorporated method. The patentable scope of the present invention is defined by the claims and may include other embodiments that a person skilled in the art may conceive. Such other embodiments are intended to be within the claims if they have structural elements that do not differ from the language of the claims, or if they include equivalent structural elements that do not substantially differ from the language of the claims. A person skilled in the art can construct further embodiments and techniques in accordance with the principles of this application by combining and adapting aspects from the various embodiments described above and other known equivalents for each such aspect. Where reference numerals related to the drawings are placed in parentheses within the claims, those reference numerals are merely for clarity of the claims and should not be construed as limiting the claims. [Explanation of Symbols]

[0095] 10 Direct-Drive Wind Turbine 12 Ground 14 Support System 15 Towers 16 Nacer 18 rotors 20 Wind Turbine Hubs 22 rotor blades 24. Blade base 26 Load transfer region 28 Wind direction 30 rotor shaft 32 Pitch System 34 Pitch axis 36 Wind Turbine Controller 38 Yaw axis 40 processors 42 Generators 44 Main shaft, rotor shaft 46 Gearbox 48 High-speed shaft 50 Couplings 52 Main frame, support 54 Separation support means 56 Yaw drive mechanism 58 Weather Measurement Systems 60 Front support bearing, main front support bearing 62 Rear support bearing, main rear support bearing 64 Drivetrain 66 Pitch Assembly 68 Pitch Drive System 70 sensors 72 pitch bearing 74 Pitch drive motor 76 Pitch Drive Gearbox 78 Pitch Drive Pinion 80 Pitch Control System 84 Power Generators 86 Hollow 88 Inner self 90 Transformer 100 ways 103 Torque Arm 140 Cooling fluid, main cooling fluid, primary cooling fluid 145 Cooling fluid, secondary cooling fluid 150 First direction 155 Second direction 160 Anterior area 165 Posterior area 200 Electrical machinery, generators 201 Bearing 203 Generator support 205 Rotation axis 210 rotors 211 Rotary Rim 212 Active rotor element, active element 215 Air Gap 220 stator 221 Stator Rim 222 Active stator element, active element 231 Drive side cover, front side cover 232 Center side cover 233 Non-drive side cover, rear cover 234 Drive side 235 Non-driven side 236 Primary entrance, exit 237 Radial space, gap 240 Radial 241 Axis 242 Circumferential direction 256 Primary entrance, primary exit 262 Central side plate 263 Non-drive side or rear plate 300 Cooling System 310 Fluid displacement devices, cooling fluid propulsion systems, propellers, bidirectional fans 310' Fluid displacement device, propeller, bidirectional fan 315 Heat exchanger 320 Inlet conduit, inlet cooling conduit 330 Outlet conduit, outlet cooling conduit 340 Additional cooling conduits 350 valve 360 thresholds, threshold temperature, maximum achievable temperature 365 thresholds, temperature thresholds 370 threshold 380 period 381 Solid line 382 Dashed line 383 Dashed line 400 assemblies

Claims

A method (100) for cooling a generator of a direct drive wind turbine, comprising: The generator includes a rotor (210) including a plurality of active rotor elements (212), a stator (220) including a plurality of active stator elements (222), and an air gap (215) separating the active rotor elements (212) from the active stator elements (222), and the method (100) includes: Supplying a cooling fluid (140) to the air gap (215) through one or more primary inlets (236) of the electromechanical machine (200) to cool the plurality of active elements (212) of the rotor (210) and / or the plurality of active elements (222) of the stator (220), and extracting the cooling fluid from the electromechanical machine (200) through one or more primary outlets (256) of the electromechanical machine (200); Reversing the direction of flow of the cooling fluid (140) such that the cooling fluid (140) is supplied to the air gap (215) through the one or more primary outlets (256) and extracted from the electromechanical machine (200) through the one or more primary inlets (236); Including; The cooling fluid (140) is supplied in a first direction (150) during a first period, and the cooling fluid (140) is supplied in a second direction (155) during a second period, and the second direction (155) is opposite to the first direction (150); The method (100), wherein the first direction (150) and the second direction (155) are substantially axial (241). Claim 2 The method (100) according to claim 1, wherein the reversing step (120) includes reversing the rotational direction of one or more fluid displacement devices (310, 310') to flow the cooling fluid (140) towards the air gap (215) to cool the air gap (215). Claim 3 The method (100) according to claim 1, wherein the reversing step (120) includes selectively fluidly connecting one or more inlet cooling conduits (320) for guiding the cooling fluid (140) towards the air gap (215) to one or more outlet cooling conduits (330) for guiding the cooling fluid (140) away from the air gap (215). Claim 4 Fluidly connecting includes redirecting the cooling fluid (140) through an additional cooling conduit (340) that operates a plurality of valves (350) to connect one or more inlet cooling conduits (320) to one or more outlet cooling conduits (330), the method (100) of claim 3.

5. The step of reversing (120) is performed only once during the expected life of the electromechanical (200), the method (100) of claim 1.

6. The step of reversing (120) is performed when or after a predetermined temperature threshold (360, 365, 370) of one or more active elements is achieved, the method (100) of claim 1.

7. The cooling fluid (140) is air, the method (100) of any one of claims 1 to 6.

8. A direct drive wind turbine comprising a generator and a cooling system (300) fluidly connected to the generator, The generator (200) includes a rotor (210) including a plurality of active rotor elements (212) that are magnetically and / or electrically active, a stator (220) including a plurality of active stator elements (222) that are magnetically and / or electrically active, and an air gap (215) separating the active rotor elements (212) from the active stator elements (222). The cooling system (300) includes one or more inlet cooling conduits (320) configured to guide a cooling fluid (140) toward the air gap (215), and one or more outlet cooling conduits (330) configured to collect the cooling fluid (140) heated within the air gap (215) and guide it away from the electromechanical (200). The cooling system (300) is configured to reverse the direction of flow of the cooling fluid (140), direct drive wind turbine.

9. The cooling system (300) further includes one or more cooling fluid displacement devices (310, 310') configured to rotate in two opposite directions to reverse the direction of flow of the cooling fluid (140), the direct drive wind turbine of claim 8.

10. The one or more cooling fluid displacement devices (310, 310') are one or more fans, the direct drive wind turbine of claim 9.

11. The direct drive wind turbine according to claim 8, wherein the cooling system (300) further comprises one or more additional conduits (340) configured to selectively fluidly connect one or more inlet conduits (320) and one or more outlet conduits (330).

12. The direct drive wind turbine according to claim 11, wherein the cooling system (300) further comprises one or more valves (350) configured to operate to allow or prevent the flow of the cooling fluid (140) through the one or more additional conduits (340).

13. One or more temperature sensors configured to measure the temperature (381, 382, 383) of one or more active rotor elements (212) and / or one or more active stator elements (222); A controller configured to instruct to change the direction of the flow of the cooling fluid (140) based on the temperature measurements of the one or more temperature sensors The direct drive wind turbine according to any one of claims 8 to 12, further comprising.

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