Electric machine cooling structure

Abstract

The present application relates to an electric machine cooling configuration, the electric machine comprising a housing in which a stator and a rotor are disposed, the electric machine cooling configuration comprising: a fan fixed to an outer side of the housing; the air outlet is formed in the wall of the shell and communicates with the fan; the first air inlet and the second air inlet are formed in the wall of the shell and guide air into the shell; and a wind deflector surrounding a winding end portion of the stator coil in an entire circumferential direction of the stator. The air guide plate is arranged on the axial inner side of at least one part of the winding end part. An air inlet path for air to reach the winding end part is formed on the axial outer side surface of the air deflector; and an air outlet path for guiding the air is formed on the axial inner side surface. The first air inlet is formed in the same side of the fan, and the second air inlet is formed in the opposite side of the fan. According to the invention, different positions in the electric machine can be uniformly cooled, and the air cooling efficiency can be ensured.

Description

Technical Field

[0001] The present application relates to a cooling structure for an electric machine. Background Art

[0002] It is well known that for electric machines, especially generators, it is necessary to cool the stator and rotor therein in a timely manner to avoid damage to the electric machine due to heat accumulation.

[0003] Generally, air is used for cooling. The path of this air cooling is to guide the air outside the electric machine into the electric machine, and then guide the air to the positions at the drive end and / or non-drive end of the rotor and / or stator of the electric machine, and then further guide the air into the rotor and / or stator through the drive end and / or non-drive end and out through the gaps therein, and then guide the heated and cooled air out of the electric machine, thereby realizing the cooling process of the electric machine. With this circulation of air, the heat inside the electric machine can be taken away.

[0004] However, the number and distribution of the air inlets for guiding air into the electric machine are usually uneven, so that the newly guided air into the electric machine usually cannot be evenly distributed, resulting in uneven cooling effect on the electric machine, and there is still a possibility of damaging the electric machine due to this. As an example, for the solution where the air inlets and fans are arranged at the top of the electric machine, the newly guided air into the electric machine obviously cannot sufficiently cool the lower part of the electric machine, resulting in a significant temperature difference between the upper and lower sides of the stator and rotor.

[0005] Therefore, a cooling structure for an electric machine is needed, which on the one hand can increase the intake of external air and ensure that the newly introduced air can evenly cool the electric machine, especially its rotor and / or stator; and on the other hand can optimize the air flow path so that the air introduced into the electric machine is used for cooling as fully as possible to ensure the cooling efficiency. Summary of the Utility Model

[0006] According to a first aspect of the present application, there is provided a cooling structure for an electric machine. The electric machine includes a housing in which a stator and a rotor are disposed. The cooling structure of the electric machine includes: a fan fixed to the outside of the housing; an air outlet disposed in the wall of the housing and communicating with the fan to suck air out of the housing through it; a first air inlet and a second air inlet respectively disposed in the wall of the housing to guide air from outside the housing to its inside; and a guide vane that surrounds the winding ends of the stator coil in the entire circumferential direction of the stator and is fixed to the inside of the housing. Wherein, the guide vane is disposed on the axial inner side of at least a part of the winding ends. Wherein, the axial outer surface of the guide vane forms an air intake path for the air from the first and second air inlets to reach the winding ends, and its axial inner surface forms an air outlet path for guiding the heated air to the air outlet; and wherein, the first air inlet is disposed on the same side of the fan in the wall of the housing, and the second air inlet is disposed on the side of the housing opposite to the fan.

[0007] Optionally, the number of air outlets is one, the number of first air inlets is two, and the number of guide vanes is two. Wherein, the air outlet is axially located between the two first air inlets, and the two guide vanes are respectively located at the boundary positions between the air outlet and the corresponding first air inlets.

[0008] Optionally, the second air inlet is arranged to be completely axially outside the guide vane.

[0009] Optionally, the guide vane has at least one of the following structures:

[0010] The guide vane is an insulating guide vane;

[0011] The guide vane is in an annular shape;

[0012] The inner peripheral edge of the annular shape is at a certain distance from the winding ends;

[0013] The distance is 5 - 10 mm;

[0014] The guide vane is in a single-piece or multi-piece structure; or

[0015] The outer periphery of the guide vane is fixed to the inside of the housing via screws.

[0016] Optionally, the guide vane is arranged at a position that is one-third of the entire length of the corresponding winding end from the axial outermost edge of the corresponding one of the two winding ends.

[0017] Optionally, the second air inlet is at least partially axially outside the guide vane; and / or the second air inlet extends axially into the axial inner side of the guide vane by no more than 20 mm.

[0018] Optionally, the air deflector is fixed to the interior of the housing via a fixing ring provided on the housing, and the fixing ring includes a fixing portion capable of mating with the outer periphery of the air deflector.

[0019] Optionally, dust-proof nets or filter meshes are respectively provided at the first and second air inlets to prevent impurities from entering.

[0020] Optionally, in the axial direction of the electric machine, the air outlet is aligned with the portion of the stator located between the winding ends, and the first air inlet is aligned with the winding ends of the stator.

[0021] Optionally, the fan is a forced-air fan; the electric machine is a generator; and / or the electric machine and the fan are assembled into a direct-cooled doubly-fed wind generator.

[0022] With the electric machine cooling structure of the present application, by providing additional air inlets at appropriate positions, the amount of external air entering is increased and it is ensured that the newly introduced air can evenly cool different positions in the electric machine, thereby preventing the generation of hot spots with excessive temperatures; it also optimizes the flow path of the introduced air so that the air introduced into the electric machine can be fully utilized for cooling, thereby ensuring the air cooling efficiency. Description of the Drawings

[0023] Other remarkable features and advantages of the present application are derived from the following non-limiting description provided for illustrative purposes with reference to the following drawings, in which:

[0024] Figure 1 A cross-section of the electric machine cooling structure according to an embodiment of the present application is shown, in which the lower half of the electric machine is shown with its internal cross-sectional structure. Detailed Description of the Embodiment

[0025] The following description is substantially exemplary only and is not intended to limit the present application and its application or use. It is also understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0026] The embodiments of the present application will be further described below in conjunction with the drawings. Although in the following embodiments of the present application, at certain positions, a generator, especially a wind generator, is used as an example to describe the embodiments according to the present application, those skilled in the art will understand that the electric machine cooling structure described in the present application can be used for any electric machine that requires air cooling of the stator and / or rotor therein other than a generator without departing from the scope of the present application.

[0027] In the embodiments of the present application, the direction along which a shaft of an electric machine, particularly a generator, extends is defined as the axial direction, and the direction surrounding the axial direction is defined as the circumferential direction. Furthermore, a direction perpendicular to the horizontal ground of an electric machine placed on horizontal ground is defined as the vertical direction, and the side relatively farther from the horizontal ground is defined as the upper side.

[0028] Next, we will combine Figure 1 The detailed configuration of the electric machine cooling configuration according to an embodiment of the present application is described in detail, wherein: Figure 1 A cross section of an electric machine cooling configuration according to an embodiment of the present application is shown.

[0029] exist Figure 1 In the illustrated embodiment, an electric machine generally includes a housing 100 in which a stator 106 and a rotor 108 are disposed. Obviously, such electric machines including the stator 106 and rotor 108 are generally well known to those skilled in the art and will not be further described here. Here, the structures of the stator 106 and rotor 108 will be briefly described. In most electric machines, the stator 106 includes a stator core and stator coils surrounding the stator core; the rotor 108 includes a rotor core and rotor coils surrounding the rotor core. The rotor 108 is typically housed within the stator 106, allowing it to rotate within the stator 106. Due to this relative rotational movement and the thermal effects of the current flowing through the respective coils, heat accumulates in the stator 106 and rotor 108, causing them to heat up. To mitigate this heat and thereby prevent damage to the stator 106 and / or rotor 108 due to excessive temperatures, cooling of the stator 106 and rotor 108 is required. Typically, cooling air is directed into the gap between the stator 106 and the rotor 108 and then exits the stator 106 through gaps in, for example, the stator core and the stator coils, to achieve cooling. This is merely a description of a typical air cooling process for an electric machine including the stator 106 and the rotor 108, and is not intended to be limiting.

[0030] exist Figure 1In the illustrated embodiment, the cooling structure of the electric machine includes a blower 116 fixed to the outer side of the housing 100. As will be appreciated, in order to achieve cooling of the stator 106 and the rotor 108 using air, it is necessary on the one hand to introduce the air outside the electric machine into the interior of the housing 100 of the electric machine and on the other hand to guide the air flow through a predetermined flow path in the stator 106 and the rotor 108. For this purpose, in the embodiment of the present application, a negative pressure can be optionally formed in the housing 100 of the electric machine to suck the air outside the housing 100 of the electric machine therein and to cause the air to flow along a desired flow path through the stator 106 and the rotor 108 by means of a wind deflector 112 as described later in the present application, so as to achieve cooling of the electric machine. In the embodiment of the present application, the suction power of the blower 116 can be appropriately selected according to the cooling requirement without departing from the scope of the present application. Further, in order to ensure the intensity of the negative pressure generated in the housing 100, preferably, the blower 116 is selected as a strong cooling blower. Preferably, the blower 116 is selected as a suction blower. As an additional example, the electric machine and the blower are assembled into a direct-cooled doubly-fed wind turbine generator.

[0031] In order to be able to cooperate with the above-mentioned blower 116 to achieve air introduction, the cooling structure of the electric machine obviously further needs to include an air outlet 114, which is provided in the wall of the housing 100 and is connected to the blower 116 to suck the air out of the housing 100 via the air outlet 114; and a first air inlet 102 and a second air inlet 104, which are respectively provided in the wall of the housing 100 and guide the air from the outside of the housing 100 to the inside thereof. As described above, the blower 116 guides the air in the housing 100 to the outside of the housing 100 via the air outlet 114, so a negative pressure is generated inside the housing 100, and this negative pressure will thus cause the air outside the housing 100 to be sucked into the housing 100 via the first and second air inlets, thereby achieving continuous air flow from the first and second air inlets to the air outlet 114.

[0032] Also as described above, in order to ensure the flow path of the air introduced into the housing 100, the electric machine cooling structure according to the present embodiment further includes a wind guide plate 112. The wind guide plate 112 surrounds the winding ends 110 of the stator coil in the entire circumference of the stator 106 and is fixed to the inside of the housing 100 to hold the wind guide plate 112. The winding ends 110 of the stator coil refer to the coil portions of the stator coil that extend out of the stator core on both sides of the stator 106 in the axial direction. The existence of the winding ends 110 is well-known to those skilled in the art, and the structure of the winding ends 110 will not be described in detail herein. Obviously, the wind guide plate 112 is configured to align with and surround the winding ends 110 and is held to the housing 100 to ensure the fixation of the position of the wind guide plate 112. Optionally, the wind guide plate 112 is configured to be disposed perpendicular to the axial direction. Preferably, in the embodiment of the present application, the wind guide plate 112 is disposed on the axial inner side of at least a part of the winding ends 110. In other words, the wind guide plate 112 is configured to divide the winding ends 110 into a first part and a second part located on both sides of the wind guide plate 112, and the first part and the second part respectively represent two parts of the winding ends 110 divided by the virtual plane where the plate surface of the wind guide plate 112 is located. Therefore, the wind guide plate 112 can also be described as a plane extending along its plate surface intersecting the winding ends 110 and dividing the winding ends 110 into two parts in the axial direction.

[0033] With the help of the wind guide plate 112, the flow path of the air introduced into the housing 100 is thus determined: on the one hand, the axial outer surface of the wind guide plate 112 forms an intake path for the air from the first and second air inlets to reach the winding ends 110. That is, the air entering the housing 100 is restricted by the barrier of the wind guide plate 112 to only flow along the axial outer surface of the wind guide plate 112 and reach the winding ends 110. Due to the existence of negative pressure, the air reaching the winding ends 110 is further sucked into the gap between the stator 106 and the rotor 108. In this case, the axial inner surface of the wind guide plate 112 forms an outlet path for guiding the heated air to the air outlet 114. That is to say, the heated air that has cooled the rotor 108 and the stator 106 is restricted to the axial inner surface of the wind guide plate 112 and cannot go to the outer surface and can only be sucked out of the housing 100 via the fan 116, thereby realizing the flow of the gas. In this sense, the two sides of the wind guide plate 112 are respectively used to form the flow paths for guiding the air to enter and exit. Therefore, as Figure 1As shown, optionally, in the embodiments of the present application, in the axial direction of the electric machine, the air outlet 114 is aligned with the portion of the stator 106 located between the winding ends 110, and the first air inlet 102 is aligned with the winding ends 110 of the stator 106, so that the air entering the first air inlet 102 can cool the winding ends 110 for the first time by means of the air guide plate 112, and the heated air after cooling the stator 106 and the rotor 108 can leave the stator 106 and be discharged to the outside of the housing 100 through the air outlet 114. Therefore, the smoothness of the air flow path is ensured and no significant turbulence occurs.

[0034] Preferably, in the embodiments of the present application, the first air inlet 102 is optionally provided on the same side of the housing 100 as the fan 116 in the wall of the housing 100, and the second air inlet 104 is provided on the side of the housing 100 opposite to the fan 116. That is to say, the first and second air inlets generally face each other (facing up and down in the Figure 1 embodiment), so that air can be introduced into the housing 100 through the two opposite sides respectively. This introduction method will ensure that the introduced air cools different regions of the stator 106 and the rotor 108 respectively, especially preventing the situation that the air introduced through the first air inlet 102 due to the unilateral arrangement of the fan 116 will preferentially cool the unilateral side (the unilateral side of the stator and the rotor) and it is difficult to diffuse to or flow to the opposite side of the unilateral side, thereby ensuring uniform cooling, preventing heat accumulation on any side, and thus avoiding possible damage to the stator 106 and / or the rotor 108.

[0035] By way of example and preferably, in the embodiments of the present application, the number of air outlets 114 is one, that is, one air outlet 114 is connected to the blower 116. Optionally, the number of the first air inlets 102 is two, that is, on one side of the blower 116, two first air inlets 102 are provided. Preferably, in the case of two first air inlets 102, they are respectively arranged on both sides of an air outlet 114 in the axial direction, so that the two first air inlets 102 can respectively guide air to the corresponding winding ends 110 at both ends of the stator 106. In the case of two first air inlets 102, in order to respectively guide the air from the first air inlets 102 to the corresponding winding ends 110 and ensure that the heated air can be discharged from the air outlet 114, the number of the air guide plates 112 is also selected to be two and are respectively located at both ends of the stator 106. In other words, in the case of one air outlet 114, two first air inlets 102 and the corresponding two air guide plates 112, the air outlet 114 is axially located between the two first air inlets 102, and preferably the two air guide plates 112 are respectively located at the boundary positions between the air outlet 114 and the corresponding first air inlets 102 to ensure that the air from the corresponding first air inlets 102 can flow along the expected flow path to achieve the desired cooling. Preferably, the two first air inlets 102 are symmetrically arranged with respect to a plane perpendicular to the axial direction and centered on the stator 106 to ensure uniform cooling of the winding ends 110 and stable flow of the air introduced into the housing 100.

[0036] As an example and preferably, the second air inlet 104 is arranged to be completely axially outside the air deflector 112 in the axial direction, that is, the air introduced through the second air inlet 104 completely flows along the outer axial surface of the air deflector 112 and flows to the winding end 110 of the stator coil, and thus will not directly enter the axial inner side of the air deflector 112. This arrangement is advantageous. If the air from the second air inlet 104 can directly enter the axial inner side of the air deflector 112, that is, directly communicate with the space on the axial inner side of the air deflector 112, then due to the relative arrangement of the second air inlet 104 and the fan 116, the air entering through the second air inlet 104 may interfere with the flow of the heated air exiting the stator 106 by the centrifugal action of the rotor 108. However, considering that the direct entry of external air into the axial inner side of the air deflector 112 may promote heat exchange due to the lower temperature, therefore, this arrangement where the second air inlet 104 is arranged to be completely axially outside the air deflector 112 in the axial direction is only exemplary and not restrictive. As an example and optionally, the second air inlet 104 can be selectively configured to be at least partially axially outside the air deflector 112 in the axial direction. However, as described above, in order to reduce the obstruction and interference of the air from the second air inlet 104 directly entering the axial inner side of the air deflector 112 on the heated air exiting the stator 106, the distance that the second air inlet 104 extends axially into the axial inner side of the air deflector 112 is selected to be relatively small, for example, not exceeding 20 mm. It should be noted that this dimension is only exemplary and not restrictive, and the selection of this extension distance is obviously associated with the size of the stator 106, the power of the fan 116, the rotational speed of the electric machine, etc. Those skilled in the art can select an appropriate such extension distance according to needs, and the selection of these distances is naturally included in the scope claimed in this application.

[0037] Here, the detailed structure of the air deflector 112 in the cooling structure of the electric machine according to the embodiments of the present application will be described in detail. It should be understood that these structures are only exemplary and not restrictive, and an air deflector 112 can selectively have any combination of one or more of the following structures, unless such a combination is technically completely contradictory and impossible to achieve.

[0038] Optionally, in the embodiments of the present application, the air deflector is an insulating air deflector 112. As described above, the air deflector 112 is arranged axially inside at least a part of the winding end 110, that is, the air deflector 112 radially surrounds the winding end 110 of the stator coil inside. In order to prevent any interference between the air deflector 112 and the stator coil, especially electrical interference, the air deflector 112 can be selectively chosen to be insulating.

[0039] Optionally, the air deflector 112 is annular. Thus, the air deflector 112 surrounds the winding end 110 at its inner edge. Of course, this shape is merely exemplary and not restrictive. Those skilled in the art can set the air deflector 112 to any appropriate shape as long as it is ensured that the air deflector 112 surrounds the winding end 110 at its inner edge.

[0040] Optionally, the inner peripheral edge of the annular air deflector 112 is at a certain distance from the winding end 110, that is, it does not contact the winding end 110. This configuration is advantageous. On the one hand, it can ensure that the air deflector 112 will not only electrically interfere with the stator coil, but also physically will not interfere with the stator coil. On the other hand, this gap leaves a certain gap between the winding end 110 and the air deflector 112. This gap provides an additional flow path for the air introduced into the housing 100 through the first and second air inlets to enter the axial inner side of the air deflector 112. Thus, a part of the air can directly enter the axial inner side of the air deflector 112 without cooling the winding end 110 and then be further extracted by the fan 116, improving the cooling efficiency. Preferably, this distance of the gap should not be too large. Optionally, the distance is 5-10 mm. It should be understood that this size is merely exemplary and not restrictive. The selection of this distance dimension is obviously related to the outer diameter of the winding end 110 of the stator coil, the size of the stator 106, the power of the fan 116, etc. Those skilled in the art can select an appropriate such distance according to needs, and the selection of these distances is naturally included in the scope claimed in the present application.

[0041] Optionally, the air deflector 112 can be selectively manufactured as a single piece or in a multi-piece configuration. For the annular air deflector 112, the annular shape can be integrally machined from a single plate or assembled from multiple components. Obviously, any possible processing method for the air deflector 112 is possible and is included in the scope of the present application.

[0042] Optionally, the outer periphery of the air deflector 112 is fixed to the inside of the housing 100 via a fixing device, such as any possible fixing device like screws, rivets, snaps, etc., to ensure the retention of the air deflector 112.

[0043] As mentioned above, in the embodiment of the present application, the air deflector 112 is disposed on the axial inner side of at least a part of the winding end 110. As an example and preferably, the air deflector 112 is disposed at a position that is one-third of the entire length of the corresponding winding end 110 from the axially outermost edge of the corresponding winding end 110. Here, it should be understood that "one-third" means that the distance from the initial intersection point of the virtual plane where the plate surface of the air deflector 112 is located and the winding end 110 (i.e., the intersection point on the circumferentially outer surface of the winding end 110) to its axially outermost edge is one-third of the entire length of the corresponding winding end 110.

[0044] Optionally and in an embodiment of the present application, in order to fix the air deflector 112 to the interior of the housing 100, a fixing ring may be selectively provided such that the air deflector 112 is fixed to the interior of the housing 100 via the fixing ring provided on the housing 100. Preferably, the fixing ring is fixedly provided around the inner wall of the housing 100 inside the housing 100. As a variant, the housing 100 includes an opening in its wall and the opening can be passed through by a separate fixing ring such that the fixing ring can be inserted into the housing 100 and fixed to the housing 100 separately. Obviously, the fixing ring includes a fixing portion capable of cooperating with the outer periphery of the air deflector 112 such that, for example, the fixing ring includes a second lug capable of cooperating with a first lug located on the outer periphery of the air deflector 112, the fixing ring includes a second buckle capable of cooperating with a first buckle located on the outer periphery of the air deflector 112, etc. These cooperation methods are merely exemplary and not restrictive.

[0045] Preferably, in an embodiment of the present application, in order to prevent external impurities from entering the housing 100 through the first and second air inlets along with the air flow, dust-proof nets or filter meshes are respectively provided at the first and second air inlets to prevent impurity intrusion.

[0046] As will be understood, in order to ensure the air suction effect, that is, to generate a negative pressure effect in the housing 100, the fan 116 can be selected as a forced air cooling fan, but this is merely exemplary, and those skilled in the art can select any suitable type of fan based on the cooling needs without departing from the scope of the present application.

[0047] Although the embodiments of the present application have been specifically described above in conjunction with the accompanying drawings, those of ordinary skill in the art can make various modifications or substitutions to the above embodiments according to the teachings of the present application without departing from the scope of the present application.

Claims

1. A cooling structure for an electric machine, characterized in that, The electric machine includes a housing (100) in which a stator (106) and a rotor (108) are provided. The cooling mechanism of the electric machine includes: a fan (116) fixed to the outer side of the housing (100); an air outlet (114) provided in the wall of the housing (100) and communicating with the fan (116) to suck air out of the housing (100) through it; a first air inlet (102) and a second air inlet (104) respectively provided in the wall of the housing (100) to guide air from outside the housing (100) to its inside; and a wind guide plate (112) that surrounds the winding ends (110) of the stator coil in the entire circumferential direction of the stator (106) and is fixed to the inside of the housing (100). Wherein, the wind guide plate (112) is provided on the axial inner side of at least a part of the winding ends (110). Wherein, the axially outer side surface of the wind guide plate (112) forms an air inlet path for the air from the first and second air inlets to reach the winding ends (110), and its axially inner side surface forms an air outlet path for guiding the heated air to the air outlet (114); and Wherein, the first air inlet (102) is provided on the same side of the fan (116) in the wall of the housing (100), and the second air inlet (104) is provided on the side of the housing (100) opposite to the fan (116).

2. The cooling structure of the electric machine according to claim 1, characterized in that, The number of the air outlets (114) is one, the number of the first air inlets (102) is two, and the number of the wind guide plates (112) is two. Wherein, the air outlet (114) is located between the two first air inlets (102) in the axial direction, and the two wind guide plates (112) are respectively positioned at the boundary positions between the air outlet (114) and the corresponding first air inlets (102).

3. The cooling structure of the electric machine according to claim 1, characterized in that, The second air inlet (104) is arranged to be completely located on the axial outer side of the wind guide plate (1,12) in the axial direction.

4. The cooling structure of the electric machine according to claim 1, characterized in that, The wind guide plate (112) has at least one of the following structures: The wind guide plate is an insulating wind guide plate (112); The wind guide plate (112) is in an annular shape; The inner peripheral edge of the annular shape is at a certain distance from the winding ends (110); The distance is 5 - 10 mm; The wind guide plate (112) is in a single-piece or multi-piece structure; or The outer periphery of the wind guide plate (112) is fixed to the inside of the housing (100) via screws.

5. The cooling structure of the electric machine according to claim 1, characterized in that, The wind guide plate (112) is arranged at a position that is one-third of the entire length of the corresponding winding end (110) from the axially outermost edge of the two winding ends (110).

6. The cooling structure of the electric machine according to claim 1, characterized in that, The second air inlet (104) is at least partially located on the axial outer side of the wind guide plate (112) in the axial direction; and / or the second air inlet (104) extends into the axial inner side of the wind guide plate (112) by no more than 20 mm in the axial direction.

7. The cooling structure of the electric machine according to claim 1, characterized in that, The air deflector (112) is fixed to the interior of the housing (100) via a fixing ring provided on the housing (100), and the fixing ring includes a fixing portion capable of mating with the outer periphery of the air deflector (112).

8. The cooling structure of the electric machine according to claim 1, wherein The first and second air inlets are respectively provided with dust-proof nets or filter nets to prevent impurities from entering.

9. The cooling structure of the electric machine according to claim 1, characterized in that, In the axial direction of the electric machine, the air outlet (114) is aligned with the portion of the stator (106) located between the winding ends (110), and the first air inlet (102) is aligned with the winding ends (110) of the stator (106).

10. The cooling structure of the electric machine according to claim 1, characterized in that, The fan (116) is a forced air-cooling fan (116); the electric machine is a generator; and / or the electric machine and the fan are assembled into a direct air-cooled doubly-fed wind turbine generator.

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