Cooling of active elements of electrical machines

Abstract

To provide electrical machines and methods for cooling active elements of the electrical machines.SOLUTION: The present disclosure relates to electrical machines and methods for cooling active elements of the electrical machines. More specifically, the present disclosure relates to rotors of electrical machines. An electrical machine may, for example, be a generator for a direct drive wind turbine. An electrical machine comprises a rotor comprising a plurality of active rotor elements, a stator comprising a plurality of active stator elements, and an air gap separating the active rotor elements and the active stator elements. The rotor further comprises one or more rotor openings configured for letting an air flow enter the electrical machine to cool the active rotor elements and / or active stator elements in response to a rotation of the rotor.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This disclosure relates to an electromachine and a method for cooling the active elements of an electromachine. More specifically, this disclosure relates to a rotor of an electromachine. The electromachine may be, for example, a generator for a direct-drive wind turbine. [Background technology]

[0002] Electrical machinery such as motors and generators generally comprises a rotor structure and a stator structure. Large generators may be, for example, electrically excited generators or permanent magnet excited generators (PMGs). The rotor of an electrical machine rotates relative to the stator. The rotor may be an internal structure, and the stator may be an external structure. In this case, the stator, for example, radially surrounds the rotor. Alternatively, the configuration may be reversed, i.e., the rotor, for example, radially surrounds the stator.

[0003] Such generators can be used, for example, in wind turbines. Wind turbines generally consist of a rotor with a rotor hub and multiple blades. The rotor is set to rotate under the influence of wind on the blades. The rotation of the rotor shaft is driven either by directly driving the generator rotor ("direct drive type") or by 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), a length of, for example, 2 to 3 meters (79 to 118 inches), and can rotate at a low speed in the range of, for example, 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 to, for example, 50 to 500 rpm or more.

[0005] Cooling is generally important in electromechanical devices such as direct-drive wind turbine generators. 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 these elements and reduce the generator's efficiency. To reduce the temperature of the active elements of the rotor and stator, heat can be removed from them by providing cooling through an air gap that isolates them. A cooling system can be provided to reduce the temperature of the active elements of the rotor and stator.

[0006] Such a cooling system may include a primary loop. The primary loop may include a primary fluid inlet. The primary fluid, such as air, may be delivered from the primary fluid inlet to the active rotor and stator elements. For example, air may be directed to the air gap between the active rotor and stator elements. When the active elements generate heat, the fluid also generates heat. The heated primary fluid may be delivered to the primary fluid outlet. In some examples, the primary fluid outlet and inlet may be in fluid communication with the air outside the wind turbine, such as the air surrounding the nacelle. For example, the cooling system may include a fan, for example, inside the nacelle, to introduce air from the outside wind turbine through the primary fluid inlet. A conduit may carry the primary loop fluid from the primary fluid inlet to the generator air gap, and then the conduit may carry the heated primary loop fluid from the generator air gap to the primary fluid outlet.

[0007] In other examples, the primary fluid inlet and outlet may be in fluid communication with a heat exchanger. The secondary loop for the fluid may include a heat exchanger. The heat exchanger may have a heat exchanger inlet and a heat exchanger outlet. The secondary fluid can be introduced into the heat exchanger through the heat exchanger inlet, and once the secondary fluid cools the primary fluid heated in the generator air gap, the primary fluid can be removed from the heat exchanger through the heat exchanger outlet. The secondary fluid may be, for example, water or air. A conduit can be used to guide the heated primary fluid into the heat exchanger, and then, once cooled, the fluid can be discharged from the heat exchanger. The cooled primary fluid can then be guided again toward the air gap between the rotor and the active elements of the generator. [Overview of the project]

[0008] One aspect of the present disclosure provides an electromachine comprising a rotor having a plurality of active rotor elements, a stator having a plurality of active stator elements, and an air gap separating the active rotor elements from the active stator elements. The rotor further comprises one or more rotor openings configured to allow ambient airflow into the electromachine and to cool the active rotor elements and / or active stator elements in accordance with the rotation of the rotor.

[0009] According to this embodiment, when the rotor is rotated, air can be drawn in through one or more rotor openings. Once inside the electromachine, the air can pass through air gaps separating the active elements of the rotor and stator, for example, radially or axially, and can generate heat. The heated air can be discharged from the generator and thus cool the active rotor and stator elements. The active components of the rotor and stator can be cooled by forced convection, eliminating the need for a cooling system with tubes and fans for introducing air into the electromachine.

[0010] Active elements used throughout this disclosure can be considered as magnetically and / or electrically active rotor or stator elements.

[0011] The electrical machinery may be a generator, particularly a generator for wind turbines, and more specifically, a generator for direct-drive wind turbines.

[0012] In a further embodiment, a method for cooling an electromachine is provided. The electromachine comprises a rotor, a stator, and an air gap separating the rotor and the stator. The method includes rotating the rotor such that a cooling airflow from the outside of the electromachine flows into the inside of the electromachine through one or more openings in the rotor.

[0013] In yet another embodiment, a generator for a direct-drive wind turbine is provided. The generator comprises a rotor having a plurality of active rotor components, a stator having a plurality of active stator components, and an air gap separating the active components of the rotor from the active components of the stator. The rotor has one or more openings configured to create a pressure difference between the inside and outside of the generator as a result of the rotation of the rotor, the pressure being lower inside the generator than outside the generator. [Brief explanation of the drawing]

[0014] [Figure 1] This diagram schematically shows a perspective view of an example 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 cross-sectional view of an example of an electrical machine. The electrical machine may be a generator for a direct-drive wind turbine. [Figure 4A] This is a schematic diagram showing cross-sections of different examples of electrical machinery. [Figure 4B] This is a schematic diagram showing cross-sections of different examples of electrical machinery. [Figure 4C] This is a schematic diagram showing cross-sections of different examples of electrical machinery. [Figure 5] This diagram schematically shows a perspective rear view of a generator for a direct-drive wind turbine. [Figure 6]FIG. is a schematic diagram showing a flowchart of an example of a method for cooling an active rotor element and a stator element.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided as an illustration of the present disclosure, not as a limitation thereof. It will be apparent to those skilled in the art that various modifications and changes can be made to the present disclosure without departing from the scope and spirit thereof. For example, features illustrated or described as part of one embodiment can be used in conjunction with another embodiment to yield further embodiments. Accordingly, the present disclosure is intended to embrace such modifications and changes that fall within the scope of the appended claims and their equivalents.

[0016] Although a generator for a direct drive wind turbine is referenced herein, the present disclosure can generally be applied to electric machines.

[0017] Figure 1 is a perspective view of an example of a wind turbine 10. In this example, the wind turbine 10 is a horizontal-axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In this example, 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 outward from the hub 20. In this example, the rotor 18 has three rotor blades 22. In an alternative embodiment, the rotor 18 includes more or fewer than three rotor blades 22. The tower 15 can be fabricated from tubular steel to define a cavity (not shown in Figure 1) between the support system 14 and the nacelle 16. In an alternative embodiment, the tower 15 is any suitable type of tower having any suitable height. In alternative configurations, the tower may be a hybrid tower comprising concrete and tubular steel sections. Alternatively, the tower may be a partial or complete grid tower. The wind turbine 10 can be mounted both on land and at sea.

[0018] The rotor blades 22 may be spaced apart around the hub 20 to facilitate the rotation of the rotor 18 and to allow kinetic energy to 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 with a plurality of load transfer regions 26. The load transfer regions 26 may have hub load transfer regions and blade load transfer regions (neither of which are shown in Figure 1). The load induced on the rotor blades 22 is transferred to the hub 20 via the load transfer regions 26.

[0019] In an example, the rotor blade 22 can have a length in the range of about 15 meters (m) to about 90 m or more. The rotor blade 22 may have any suitable length that enables the wind turbine 10 to function as described herein. For example, non-limiting examples of blade lengths include lengths less than 20 m, 37 m, 48.7 m, 50.2 m, 52.2 m, or greater than 91 m. When wind hits the rotor blade 22 from the wind direction 28, the rotor 18 rotates about the rotor shaft 30. When the rotor blade 22 rotates and is subject to centrifugal force, the rotor blade 22 also receives various forces and moments. Thus, the rotor blade 22 can deflect and / or rotate from a neutral or non-deflected position to a deflected position.

[0020] Furthermore, the pitch angle of the rotor blade 22, i.e., the angle that determines the orientation of the rotor blade 22 with respect to the wind direction, is changed by the pitch system 32, and by adjusting the angular position of at least one rotor blade 22 with respect to the wind vector, the load and power generated by the wind turbine 10 can be controlled. The pitch axis 34 of the rotor blade 22 is also shown. During operation of the wind turbine 10, the pitch system 32 can specifically change the pitch angle of the rotor blade 22 such that the angle of attack of (a part of) the rotor blade is reduced, thereby facilitating a reduction in the rotational speed and / or facilitating a stall of the rotor 18.

[0021] In this example, 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 for all rotor blades 22 may be controlled simultaneously by the control system.

[0022] Furthermore, in this example, as the wind direction 28 changes, the yaw direction of the nacelle 16 can be rotated about the yaw axis 38 to position the rotor blade 22 with respect to the wind direction 28.

[0023] In this example, 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 carry out the methods and / or steps described herein. Furthermore, many of the other components described herein include processors.

[0024] 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 processors and / or control systems may also include memory, input channels, and / or output channels.

[0025] Figure 2 is an enlarged cross-sectional view of a portion of the wind turbine 10. In this example, 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 example, the main shaft 44 is positioned 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 in turn drives the high-speed shaft 48 by converting the relatively slow rotational motion of the rotor 18 and the main shaft 44 into the relatively fast rotational motion of the high-speed shaft 48. The latter is connected to the generator 42 to produce 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.

[0026] 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 example, 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.

[0027] 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.

[0028] In some examples, the wind turbine may be a direct-drive wind turbine without a gearbox 46. The generator 42 operates at the same rotational speed as the rotor 18 in the direct-drive wind turbine. Therefore, they generally have a much larger diameter than the generators used in wind turbines with a gearbox 46 in order to provide a similar amount of power as wind turbines with a gearbox.

[0029] The nacelle 16 may also include a yaw drive mechanism 56 that can be used to rotate the nacelle 16, and by extension the rotor 18, around the yaw axis 38, and to control the viewpoint of the rotor blades 22 with respect to the wind direction 28.

[0030] To properly position the nacelle 16 with respect to the wind direction 28, the nacelle 16 may also include at least one weather measurement system, which may include a wind vane and an anemometer. The weather measurement system 58 can provide the wind turbine controller 36 with information, which may include wind direction 28 and / or wind speed. In this example, 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.

[0031] In this example, the pitch assembly 66 includes a hub 20 and at least one pitch bearing 72 coupled to each rotor blade 22 (shown in Figure 1) to rotate each rotor blade 22 around 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.

[0032] 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 example, 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 component, but is not limited to, a hydraulic cylinder, spring, and / or servo mechanism. In a particular embodiment, the pitch drive motor 74 is driven by energy extracted from a stored energy source (not shown) that supplies the rotational inertia and / or energy of the hub 20 to the components of the wind turbine 10.

[0033] 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 example, the pitch assembly 66 includes at least one pitch control system 80 communicably coupled to each pitch drive system 68 in order to control the pitch drive system 68 independently of the wind turbine controller 36. In this example, the pitch control system 80 is coupled to the pitch drive system 68 and the sensor 70. During normal operation of the wind turbine 10, the wind turbine controller 36 can control the pitch drive system 68 to adjust the pitch angle of the rotor blades 22.

[0034] 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 example, 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 depletion, 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.

[0035] In this example, 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.

[0036] In one aspect of the present disclosure, an electromachine 100 is provided. The electromachine 100 comprises a rotor 110 and a stator 120. The rotor 110 comprises a plurality of active rotor elements 112, and the stator 120 comprises a plurality of active stator elements 122. An air gap 115 separates the active rotor elements 112 and the active stator elements 122. The rotor further comprises one or more rotor openings 150 configured to allow ambient airflow into the electromachine and to cool the active rotor elements and / or active stator elements in accordance with the rotation of the rotor.

[0037] The air entering the electromachine can cool the rotor and stator active elements without the need for guide conduits for air, fans, and / or heat exchangers. The rotation of the rotor 110 may be sufficient to draw ambient air into the electromachine 100 and cool the active elements 112, 122.

[0038] Figure 3 schematically shows a cross-sectional view of an example of an electromachine 100. The electromachine 100 comprises a rotor 110, a stator 120, and an air gap 115 between the rotor 110 and the stator 120. The rotor 110 is configured to rotate about a rotation axis 105. In this example, the air gap 115 is a radial air gap, and the electromachine is a radial generator for a direct-drive wind turbine, but in other examples, the electromachine 100 may be an axial electromachine with an axial air gap. In Figure 3, the rotor 110 surrounds the stator 120. In other examples, the stator may surround the rotor.

[0039] The stator 120 comprises a stator rim 121 and a plurality of active stator elements 122. The rotor 110 comprises a rotor rim 111 and a plurality of active rotor elements 112. The active stator elements 122 may be one or more permanent magnets, one or more permanent magnet modules, one or more coils, or one or more coil modules. Similarly, the active rotor elements 112 may be one or more permanent magnets, one or more permanent magnet modules, one or more coils, or one or more coil modules. For example, the active stator elements 122 may be coils, and the active rotor elements 112 may be permanent magnet modules. In other examples, both the active stator elements 122 and the active rotor elements 112 may be coils. An air gap 115 separates the active elements 112 of the rotor from the active elements 122 of the stator.

[0040] Multiple permanent magnets may be provided in a permanent magnet module, which may be mounted to the rotor 110 as a single component. The permanent magnet module may be defined as a unit having multiple permanent magnets, so that the multiple magnets can be mounted together and unmounted together. Such a module may have a module base having a shape suitable for housing or supporting multiple permanent magnets that can be fixed to a base. The base may be configured to be fixed to a rotor structure such as a rotor rim 111 so that the multiple magnets are fixed together to the rotor rim 111 through the module base. The use of a permanent magnet module can facilitate the manufacture of the rotor 110. Similarly, stator coils may be grouped together in a coil module. The coil module may be fixed to a generator structure such as a stator rim 121.

[0041] The rotor 110 may include a drive side 161, a center side 162, and a non-drive side 163. The drive side 161 may also be called the front side 161 and may be configured to face the wind turbine hub 20. On the drive side 161, the rotor may include a drive side cover 131 that can extend mainly radially 140 and tangentially or circumferentially 142. The drive side cover 131 can protect the active elements of the rotor and stator from undesirable wind particles such as moisture and dust in the axial direction 141. On the center side 162, the rotor may include a rotor rim 111 and a center side cover 132 that can extend mainly circumferentially 142 and axially 141. The rotor may further include a non-drive side cover 133 on the non-drive side 163. The non-drive side 163 may also be called the rear side 163. The central cover 132 may extend between the front cover 131 and the rear cover 133 of the rotor 110.

[0042] The stator 120 can be fixedly mounted to the generator support 103. The rotor 110 may be rotatably mounted to the generator support 103 and may be connected to the hub 20 of the wind turbine 10. The first side 131 of the rotor 110 may be joined to the generator support 103 by bearings (not shown). If the rotor 110 includes a non-driven side cover 133 extending to the generator support 103, the non-driven side cover 133 may also be joined to the support 103 using bearings. The generator support 103 may be the front of a wind turbine frame, such as a direct-drive wind turbine frame.

[0043] The openings 150 may be located on any of the cover sides of the rotor 110, such as the front 131, the center 132, and the rear 133. For example, one or more rotor openings 150 may be located on the drive-side cover 131 of the rotor 110. An example of this option is schematically shown in Figure 4A. Since the drive-side cover 131 can be configured to be upstream, if one or more front openings 150 are provided, ambient airflow can naturally enter the generator 100. The rotation of the rotor 110 can help circulate the airflow through the generator 100, particularly through the air gap 115 between the active elements of the rotor and stator. The rotation of the rotor 110 reduces the pressure inside the rotor, drawing ambient air into the rotor. Air, such as air heated after contact with the active elements 112, 122, can be discharged through the rear of the rotor 110. If the rotor includes a rear cover 133, air can exit the generator 100 through one or more outlets 153 within the rear cover 133. In other examples, the cover on the non-driven side 133 does not extend radially inward to the generator support (for example, as in Figures 4B and 4C), and air can exit the generator through the space 136 between the rear cover 133 and the generator support 103.

[0044] In some other examples, one or more rotor openings 150 can be provided in the central cover 132 of the rotor 110, for example, as shown in Figure 4B. In these examples, the rotational speed of the rotor 110 allows ambient air, for example, flowing relatively parallel to the central cover 132, to enter the generator 100 from the outside of the electromachine to the inside of the electromachine. In the electromachine 100 of Figure 3, the air entering through the central opening 150 can flow between the active elements 112 of the rotor 110 toward the air gap 115. The heated air can be discharged through the rear of the rotor 110 as described above. The opening 150 in the central 132 can extend completely from the drive-side cover 131 to the non-drive-side cover 133 of the rotor 110.

[0045] In yet another example, one or more openings 150 may be provided in the rear cover 133 of the rotor 110, for example, as shown in Figure 4C. The rotation of the rotor 110 can draw ambient air near the rear cover 133 into the generator 100, causing it to flow across the air gap 115 and reduce the temperature of the active rotor and stator elements. One possible method for discharging the air in the air gap 115 may be to circulate the heated air near the front cover 131 of the rotor through the stator 120 to the rear of the rotor, as shown in Figure 4C. The stator 120, for example, the stator frame, may have an inlet and an outlet for this purpose. In the example in Figure 4C, a window 124 is provided to allow the transmission of a cooling flow through the stator. The inlet may be provided in the first cover or front cover (if present) of the stator, and the outlet may be provided in the second cover or rear cover (if present) of the stator. After the heated air has passed over the stator 120, the air may be discharged through one or more outlets 153 in the rear cover 133 of the rotor 110, or through the space 136 between the rotor 110 and the generator support 103.

[0046] In the example above, the rotor 110 surrounds the stator 120, particularly in the radial direction. Having the rotor 110 around the stator 120 facilitates the flow of ambient air into the generator 100 and through the air gap 115 to cool the active elements of the rotor and stator. In other examples, the stator 120 may surround the rotor 110.

[0047] In Figures 4A to 4C, the rotor opening 150 is shown on only one side cover of the rotor 110. However, the opening 150 may be provided on multiple side covers of the rotor 110. For example, one or more openings 150 may be provided on the central side cover 132 of the rotor, or one or more openings may be provided on the rear side cover 133 of the rotor. Similarly, one or more openings 150 may be provided on the drive side cover 131 of the rotor, or one or more openings may be provided on the non-drive side cover 133 of the rotor. One or more openings on the drive side cover 131 can be aligned with one or more openings on the non-drive side cover 133 in the axial direction 141. In general, the location of the opening 150 can be adapted to form a suitable path for airflow along and / or through the electromechanism 100.

[0048] The rotor openings 150 may be distributed along the circumferential direction 142. Figure 5 shows a perspective view of the rotor 110 from the rear. In this figure, the rotor 110 has a rear cover 133. The rear cover 133 is an annular cover 140 having multiple segments 145. Therefore, when mounted on the generator support 103, the rear cover 133 is not joined to the support 103. In some examples, the annular cover 140 can be attached to the flange of the central cover 132 of the rotor.

[0049] In Figure 5, six segments 145 have been removed from the annular cover 140. As the rotor 110 rotates around the shaft 105, the pressure inside the rotor 110 may decrease, allowing ambient air to be introduced into the generator 100, which can reduce the temperature of the active rotor and stator elements. By providing multiple air inlets along the circumferential direction 142, the amount of air in contact with the active elements 112 and 122 can be increased. Thus, cooling can be enhanced.

[0050] The rotor openings 150 have a certain area. The sum of the areas of the openings 150 on the rotor can be called the total area. In some examples, the total area of ​​the rotor openings 150 can represent 10% to 40%, more specifically 10% to 25%, of the total surface area of ​​the rotor side covers. For example, if the openings 150 are provided only on the rotor side covers 131, 132, and 133, the openings 150 can occupy 10% to 25% of the total (external) surface area of ​​the rotor covers. In some examples, the surface area occupied by the openings may be about 15% of the total (external) surface area of ​​the rotor. In other examples where the openings 150 are provided on multiple side covers of the rotor, the total area of ​​the openings may be about 15% of the total (external) surface area of ​​the rotor. Sufficient structural integrity of the rotor 110 and sufficient cooling of the active elements 112 and 122 may be provided within this range.

[0051] In some examples, the rotor opening 150 is up to 2m 2 It can have an area of ​​(square meters). In some of these examples, the rotor opening 150 is 0.3 m 2 ~1.5m 2 It can have an area of ​​approximately 1.1 m². For example, the rotor opening 150 may have an area of ​​approximately 1.1 m². 2 They may have an area of ​​. Regardless of their location on the rotor-side cover, all rotor openings 150 can have substantially the same area.

[0052] In some examples, the rotor 110 may have two or more openings 150. For example, the rotor 110 may have 2 to 10 openings 150, or more specifically, 4 to 8 openings. For example, as shown in Figure 5, it may have 6 rotor openings 150.

[0053] The rotor opening 150 may be positioned to face the air gap 115. For example, in Figures 4A and 4C, the rotor opening 150 faces or is substantially aligned with the air gap 115 in the axial direction 141. In Figure 4B, the rotor opening 150 faces or is substantially aligned with the air gap 115 in the radial direction 140. This can help direct the airflow toward the air gap 115.

[0054] The electromachine 100 may further include one or more air filters 155 positioned in one or more of the rotor openings 150. Figure 5 shows the filters 155 within the openings. The filters 155 filling or covering the openings 150 can prevent or reduce the ingress of potential damaging substances from outside the generator 100, such as dust, moisture, and salt. Thus, the lifespan of the electromachine 100 can be extended. In some examples, the filters 155 are positioned together with each rotor opening 150, for example, within each rotor opening 150. The rotation of the rotor 110, for example the rotor of a direct-drive wind turbine 10, may be sufficient to overcome the pressure drop in the filters 155 and generate a pressure inside the rotor 110 low enough to draw ambient air into the rotor.

[0055] Different types of filters 155 may be used. The filter 155 may comprise one or more filtration regions. In some examples, the first filtration region may comprise a vane separator, and the second region may comprise one or more filtration elements. One or more filtration elements may be configured to filter the air more finely than the vane separator. In addition, subsequent filtration regions may optionally be present. Thus, the air entering the rotor 110 may first be filtered in the first filtration region, then more finely filtered in the second filtration region, and if more filtration regions are present, it may be filtered in subsequent filtration regions. The filter 155 may be mounted such that, for example, the first filtration region comprising a vane separator faces outward from the rotor 110.

[0056] In some examples, the electromechanical machine 100 can further include one or more fans at one or more rotor outlets 153, 136. The fans can be used to assist in cooling. For example, if the wind speed is not sufficient to adequately cool the active elements of the rotor and stator, the fans can be turned on to create a low-pressure region and air can be flowed from the air gap 115 to the rotor outlets 153, 136.

[0057] In one aspect of the present disclosure, a method 200 is provided. The method 200 is suitable for cooling the active rotor element 112 and the active stator element 122 of the electromechanical machine 100. The method 200 is schematically shown in FIG. 6.

[0058] In some examples, the electromechanical machine can be a generator, particularly a generator for a wind turbine, more particularly a generator for a direct drive wind turbine.

[0059] For a direct drive wind turbine having a nominal power of 10 MW or more, a cooling flow with a volumetric flow rate exceeding 15 m 3 / s, specifically exceeding 20 m 3 / s, and more specifically exceeding 25 m 3 / s can be provided. To provide such a volumetric cooling flow rate, an inlet having a total surface area (including the air filter) exceeding 5 m 2 , specifically exceeding 6 m 2 , and more specifically exceeding 6.5 m 2 can be provided.

[0060] The method includes, in block 210, providing an electromechanical machine 100 comprising a rotor 110, a stator 122, and an air gap 115 separating the rotor and the stator.

[0061] The rotor openings 150 can be positioned as described above, for example, with respect to Figures 4A to 4C. One or more openings 150 may be provided in the drive-side cover 131 of the rotor, and / or one or more openings 150 may be provided in the center-side cover 132 of the rotor, and / or one or more openings may be provided in the non-drive-side cover 133 of the rotor. One or more filters 155 may be arranged together with one or more rotor openings 150, for example, inside the openings. The rotor openings may be completely covered by the filters 155 or filled.

[0062] The rotor 110 can surround the stator 120, for example, in the radial direction 140. If the electromachine 100 has this configuration, cooling can be enhanced.

[0063] The method further includes rotating the rotor 110 in block 220 such that a cooling airflow from outside the electromachine 100 flows into the inside of the electromachine through one or more openings 150 in the rotor 110. By rotating the rotor 110, ambient air flows into the electromachine 100 through the openings 150 and through the air gap 115, thereby allowing the active parts of the rotor and the active components of the stator to be cooled.

[0064] The rotor 110 can be rotated by the action of wind on one or more wind turbine blades 22.

[0065] Several factors can affect the ability to draw air into the electromachine 100, and therefore the cooling of the air gap 115. These factors may include the power of the electromachine, the rotational speed of the rotor 110, and the rotor diameter. Depending on the power of the machine and the rotor size, the number, size, and position of the rotor openings 150 can be selected to adequately cool the air gap 115. A rotor rotational speed of a direct-drive wind turbine, for example, 2-14 rpm (revolutions per minute), may be sufficient to adequately cool the air gap 115.

[0066] In yet another aspect of this disclosure, a generator 100 for a direct-drive wind turbine 10 is provided. The generator 100 comprises a rotor 110 and a stator 120. The rotor 110 comprises a plurality of active rotor components 112, and the stator 120 comprises a plurality of active stator components 122. An air gap 115 separates the active components of the rotor from the active components of the stator.

[0067] The rotor 110 includes one or more openings 150 configured to generate a pressure difference between the inside and outside of the generator 100 as a result of the rotor 110 rotating. The pressure inside the generator 100 is lower than the pressure outside the generator.

[0068] One or more rotor openings 150 are provided in at least one of the rotor's front cover, rotor's center cover, and rotor's rear cover.

[0069] The rotor 110 may have two or more openings 150. For example, the rotor 110 may have 2 to 10 openings 150, or more specifically, 4 to 8 openings. In some examples, six rotor openings 150 can be provided.

[0070] The rotor opening 150 is up to 2m 2 It can have an area of ​​(square meters). In some of these examples, the rotor opening 150 is 0.3 m 2 ~1.5m 2 It can have an area of ​​approximately 1.1 m². For example, the rotor opening 150 may have an area of ​​approximately 1.1 m². 2 They may have an area of ​​. Regardless of their location on the rotor-side cover, all rotor openings 150 can have substantially the same area.

[0071] The rotor opening 150 may extend over 10% to 40% of the entire (external) surface of the rotor-side cover, more specifically, over 10% to 25% of the entire (external) surface of the rotor-side cover. In some examples, the surface covered by the opening may be about 15% of the entire (external) surface of the rotor. One or more filters 155 may be arranged with one or more openings 150, for example, all of the openings. The filters 155 can completely fill or cover the opening 150.

[0072] The rotor 110 can surround the stator 120, for example, in the radial direction 130.

[0073] The description relating to Figures 3 to 5 can be applied to the generator 100 of this embodiment. In any of the disclosed examples, vanes, deflectors, or other flow guide elements can be provided to guide the airflow through the electromachine in the appropriate direction. For example, in the examples of Figures 4B and 4C, flow guide elements can be provided to ensure that ambient air reaches different parts of the electromachine in the circumferential and / or axial directions to provide adequate cooling to the electromachine. The flow guide elements may be provided with a selection of openings. The flow guide elements may be the same for all openings or may differ for some of the openings.

[0074] This specification discloses teachings, including preferred embodiments, using examples, and enables a person skilled in the art to practice the teachings disclosed herein, including by fabricating and using any device or system and by carrying out any incorporated methods. The patentable scope is defined by the claims and may include other examples that a person skilled in the art may conceive. Such other examples 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 may construct further embodiments and technologies 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]

[0075] 10 Direct-Drive Wind Turbine 12 Ground 14 Support System 15 Towers 16 Nacer 18 rotors 20 Wind Turbine Hubs 22 rotor blades, wind turbine 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 Electric 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 Main forward support bearing 62 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 Cavity 88 Inner self 90 Transformer 100 Electrical machinery, generators 103 Torque arm, generator support 105 Rotation axis 110 Rotor 111 Rotary Rim 112 Active rotor elements, active rotor components 115 Air Gap 120 stator 121 Stator Rim 122 Active stator element, active stator component, stator, active element 124 windows 130 Radial 131 Drive side cover, front side cover, first side 132 Center side cover 133 Non-drive side cover, rear cover 136 Space, rotor outlet 140 Radial, annular cover 141 Axis 142 Circumferential direction 145 segments 150 opening 153 Exit 155 Air filter 161 Drive side, front 162 Center side 163 Non-driven side, rear side 200 ways

Claims

1. An electromechanical machine (100), comprising: a rotor (110) having a plurality of active rotor elements (112); a stator (120) having a plurality of active stator elements (122); and an air gap (115) separating the active rotor elements (112) from the active stator elements (122), wherein: the rotor (110) further includes one or more rotor openings (150) configured to allow ambient air flow to enter the electromechanical machine (100) and to cool the active rotor elements (112) and / or the active stator elements (122) in response to rotation of the rotor (110) as the air flow passes through the air gap (115); the rotor (110) is further configured to discharge heated ambient air flow from the electromechanical machine (100), the electromechanical machine (100).

2. The electromechanical machine (100) according to claim 1, wherein an air filter (155) is disposed in one or more of the rotor openings (150).

3. The electromechanical machine (100) according to claim 2, wherein the air filter (155) includes a first filtration stage including a vane separator and, optionally, further includes a second filtration stage for additional fine filtration.

4. The electromechanical machine (100) according to claim 1, wherein one or more rotor openings (150) are provided in a drive side cover (131) and / or a central side cover (132) and / or a non-drive side cover (133) of the rotor (110).

5. The electromechanical machine (100) according to claim 1, wherein a total area of the one or more rotor openings (150) represents 10% to 40% of a total surface area of the rotor side covers (131, 132, 133).

6. One or more of the one or more rotor openings (150) are at most 2 m ２ , more particularly 0.3 m ２ to 1.5 m ２ in area, the electromechanical machine (100) according to claim 1.

7. The electromechanical machine (100) according to claim 1, wherein the rotor (110) includes two or more openings (150), particularly 2 to 10 openings (150), more particularly 4 to 8 openings (150).

8. The electromechanical machine (100) according to claim 1, wherein the rotor openings (150) are distributed along a circumferential direction (142).

9. The electromechanical machine (100) according to claim 1, further comprising one or more fans at one or more rotor outlets (153).

10. The electromechanical machine (100) according to claim 1, wherein the rotor (110) surrounds the stator (120).

11. The electromechanical machine (100) according to any one of claims 1 to 10, wherein the electromechanical machine (100) is a generator (100) for a direct drive wind turbine (10).

12. A direct drive wind turbine (10) comprising the generator (100) according to claim 11.

13. A method (200) for cooling an electromechanical machine (100) comprising a rotor (110) including a plurality of active rotor elements (112), a stator (120), and an air gap (115) separating the plurality of active rotor elements (112) and a plurality of active stator elements (122), comprising: rotating the rotor (110) (220) such that a cooling air flow from outside the electromechanical machine (100) flows into the electromechanical machine (100) through one or more openings (150) in the rotor (110); cooling the plurality of active rotor elements (112) and / or the plurality of active stator elements (122) as the cooling air flow passes through the air gap (115) in response to rotation of the rotor (110) and exits the electromechanical machine (100); A method (200) including the above.

14. The method (200) according to claim 13, wherein the rotor (110) is rotated by the action of wind on one or more wind turbine blades (22).

15. The method (200) according to claim 13 or 14, wherein the rotor (110) surrounds the stator (120).

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