Abstract:
A stator used for a motor, the motor and a ventilation cooling method for the motor. The stator includes concentrated windings, and at least two wedge blocks are arranged at the gaps between the adjacent concentrated windings. The at least two wedge blocks are distributed on the concentrated windings in a staggered manner to form a first ventilation path. Therefore, the concentrated windings can be cooled effectively, the concentrated windings are effectively constrained in the circumferential direction by means of the at least two wedge blocks, the service life of the motor is further prolonged, and the reliability of the motor is improved.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to a stator for an electric machine, an electric machine and a ventilation and cooling method thereof, and particularly to a stator of a permanent magnet machine based on concentrated windings and a ventilation and cooling method thereof. 
       BACKGROUND 
       [0002]    With the increase of capacity of a large-sized permanent magnet machine, internal losses of the permanent magnet machine also increase correspondingly, thus causing a temperature rise of the permanent magnet machine to be over-high, and further adversely affecting safe and stable operation of the permanent magnet machine. Although ventilation and cooling of the electric machine in a radial direction thereof or mixed ventilation and cooling in the radial and axial directions may meet the heat dissipating capability requirements of the large-sized permanent magnet machine, an effective material utilization rate of the large-sized permanent magnet machine is decreased due to the presence of a radial ventilation duct, and the weight and cost of the large-sized permanent magnet machine may be increased. 
       SUMMARY 
       [0003]    A stator for an electric machine, an electric machine and a ventilation and cooling method thereof are provided according to embodiments of the present application to efficiently cool the electric machine. 
         [0004]    To realize the above objects. the following technical solutions are adopted in the embodiments of the present application. 
         [0005]    A stator for an electric machine includes concentrated windings, and at least two wedges provided in a gap formed between adjacent concentrated windings, and the at least two wedges are staggered on the concentrated winding to form a first ventilation path. 
         [0006]    An electric machine includes the stator in the above technical solution. 
         [0007]    A ventilation and cooling method for an electric machine, which is implemented via the electric machine according to the above technical solutions, includes:
       separating the electric machine into a high pressure area and a low pressure area by a support configured to fix the stator; and   entering cold air into the high pressure area via pipelines, cooling the electric machine via the first ventilation path formed by a gap between the at least two wedges, and then entering the cold air into the low pressure area to change the cold air into hot air.       
 
         [0010]    In the stator for the electric machine, the electric machine, and the ventilation and cooling method of the electric machine according to the embodiments of the present application, at least two wedges are arranged in the gap formed between two adjacent concentrated windings, and since the at least two wedges are staggered, a length of the first ventilation path is extended, thus may effectively cool the concentrated windings, and may further facilitate improving a heat dissipating capability of the electric machine, improving a power density of the electric machine, and reducing an effective material consumption of the electric machine, thereby reducing the weight and cost of the electric machine. Furthermore, the wedges may also prevent a circumferential movement of the concentrated winding, thus allows the concentrated winding to be effectively constrained in a circumferential direction of a sloth, and avoids damage to the insulation of the concentrated winding resulted from the back and forth circumferential movement of the concentrated winding in the slot in a long term, thereby prolonging a service life of the electric machine, and improving the reliability of the electric machine. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a front view of a stator for an electric machine according to an embodiment of the present application; 
           [0012]      FIG. 2  is a perspective schematic view showing the structure of the stator according to the embodiment in  FIG. 1 : 
           [0013]      FIG. 3  is a schematic view of a first ventilation path according to the embodiment in  FIG. 1 ; 
           [0014]      FIG. 4  is a front view of a stator for an electric machine according to another embodiment of the present application; 
           [0015]      FIG. 5  is a perspective schematic view showing the structure of the stator according to the embodiment in  FIG. 4 ; 
           [0016]      FIG. 6  is a perspective view showing the structure of a stator for an electric machine according to yet another embodiment of the present application; and 
           [0017]      FIG. 7  is a schematic flow diagram showing a ventilation and cooling method for an electric machine according to an embodiment of the present application. 
           [0000]    
         
           
                 
               
                 
                 
                 
               
                 
                 
               
                 
                 
                 
                 
                 
               
             
                 
                     
                 
                 
                   Reference Numerals: 
                 
                 
                     
                 
               
               
                 
                     
                 
               
            
             
                 
                     
                    11 concentrated winding, 
                   12 concentrated winding, 
                 
                 
                     
                    13 concentrated winding, 
                   20 stator iron core, 
                 
               
            
             
                 
                     
                    21 first tooth portion of the stator iron core, 
                 
                 
                     
                    22 second tooth portion of the stator iron core, 
                 
                 
                     
                    23 third tooth portion of the stator iron core, 
                 
                 
                     
                   201 yoke portion of slot base, 
                 
                 
                     
                   202 axial ventilation hole of yoke portion of slot base, 
                 
                 
                     
                   203 axial ventilation hole of the tooth portion; 
                 
               
            
             
                 
                     
                    3 slot wedge, 
                   41 wedge, 
                   42 wedge, 
                   43 wedge, 
                 
                 
                     
                    44 wedge, 
                   45 wedge, 
                   46 wedge, 
                   47 wedge, 
                 
                 
                     
                    48 wedge, 
                    5 rotor, and 
                    6 support. 
                 
                 
                     
                     
                 
               
            
           
         
       
       
    
    
     DETAILED DESCRIPTION 
       [0018]    A stator for an electric machine, an electric machine, and a ventilation and cooling method thereof according to embodiments of the present application are described in detail hereinafter in conjunction with drawings. 
         [0019]      FIG. 1  is a front view showing a stator for an electric machine according to an embodiment of the present application;  FIG. 2  is a perspective schematic view showing the structure of the stator according to the embodiment in  FIG. 1 ; and  FIG. 3  is a schematic view showing a first ventilation path according to the embodiment in  FIG. 1 . As shown in  FIGS. 1 and 2 , three concentrated windings (a concentrated winding  11 , a concentrated winding  12 , and a concentrated winding  13 ), and a stator iron core  20  corresponding to the concentrated winding  11 , the concentrated winding  12 , and the concentrated winding  13  are exemplified, corresponding to the concentrated windings, the stator iron core  20  has tooth portions (for example, a first tooth portion  21  of the stator iron core, a second tooth portion  22  of the stator iron core, and a third tooth portion  23  of the stator iron core). At least two wedges are provided in a gap formed between the concentrated winding  11  and the concentrated winding  12 . As shown in  FIG. 3 , a wedge  41 , a wedge  42 , and a wedge  43  are located at upper portions of a side face of the concentrated winding, the wedge  44 , the wedge  45  and the wedge  46  are located at lower portions of the concentrated winding, and the wedge  41 , the wedge  42 , the wedge  43 , the wedge  44 , the wedge  45 , and the wedge  46  are staggered on the side face of the concentrated winding  12 , thus forming a first ventilation path. The first ventilation path forms a curved ventilation path due to the staggered distribution of the wedge  41 , the wedge  42 , the wedge  43 , the wedge  44 , the wedge  45 , and the wedge  46 . It should be understood by the person skilled in the art that, the first ventilation path according to the embodiment of the present application may also be of an up-down fluctuated shape, a wave shape, a curvilinear shape, etc., and a specific shape may be determined by positions of the wedges on the concentrated winding. Thus, the shape of the ventilation path is not limited by the embodiment of the present application, as long as a length of the first ventilation path can be extended. It should also be appreciated by the person skilled in the art that, another ventilation path may also be formed by a gap corresponding to other at least two wedges on another side surface of the concentrated winding  12  (for example, the wedge  47 , the wedge  48  are located on another other side face of the concentrated winding  12  in  FIG. 1 ), which is not described in detail in the embodiments of the present application hereinafter. 
         [0020]    In the stator for the electric machine according to the embodiment of the present application, at least two wedges are arranged in the gap formed between the concentrated winding  11  and the concentrated winding  12  that are adjacent, since the at least two wedges are staggered, the length of the first ventilation path is extended, thus may effectively cool the concentrated winding  11  and the concentrated winding  12 , and may further facilitate improving a heat dissipating capability of the electric machine, improving a power density of the electric machine, and reducing an effective material consumption of the electric machine, thereby reducing the weight and cost of the electric machine. Furthermore, the wedges may also prevent the concentrated winding  11  and the concentrated winding  12  from moving in a circumferential direction of slots, thus allowing the concentrated winding  11  and the concentrated winding  12  to be effectively constrained in the circumferential direction, and avoiding damage to the insulation of the concentrated winding  11  and the concentrated winding  12  caused by circumferential back and forth movements of the concentrated winding  11  and the concentrated winding  12  in the slots in a long term, and thereby prolonging a service life of the electric machine, and improving the reliability of the electric machine. 
         [0021]      FIG. 4  is a front view of a stator for an electric machine according to another embodiment of the present application, and  FIG. 5  is a perspective schematic view showing the structure of the stator for the electric machine according to the embodiment shown in  FIG. 4 . As shown in  FIGS. 4 and 5 , and based on the embodiment in  FIGS. 1 and 2 , the first tooth portion  21 , the second tooth portion  22  and the third tooth portion  23 , and a yoke portion of slot base  201  are respectively provided with an axial ventilation hole  202  and an axial ventilation hole  203 , and the axial ventilation hole  203  forms a second ventilation path in the third tooth portion  23  of the stator iron core, and the axial ventilation hole  202  forms a third ventilation path in the yoke portion of slot base  201 . 
         [0022]    Further, each trapezoidal-shaped wedge of the at least two wedges is wrapped with an insulation felt, and is fixed in the gap between two adjacent concentrated windings via the insulation felt. By wrapping the insulation felt on each of the at least two wedges, the insulation of the concentrated winding  11  and the concentrated winding  12  may be protected, in addition, the wedge may be formed integrally with the concentrated winding after the stator iron core  20  is processed through a vacuum pressure impregnating (Vacuum Pressure Impregnating, which is abbreviated as VPI), and further the wedges may be effectively fixed between the concentrated winding  11  and the concentrated winding  12 , and stator iron core  20  may be effectively fixed in the slot. Further, the first tooth portion  21 , the second tooth portion  22 , and the third tooth portion  23  of the stator iron core  20  are parallel teeth, and each of the slots corresponding to the stator iron core  20  is a trapezoidal-shaped slot. After the concentrated winding  11  and the concentrated winding  12  are fitted in the respective trapezoidal-shaped slots, the gap between two adjacent concentrated windings forms a trapezoidal-shaped gap. 
         [0023]    Moreover, the at least two wedges specifically include a first wedge group and a second wedge group, and each of the first wedge group and the second wedge group includes at least one wedge. As shown in  FIG. 3 , the first wedge group specifically includes the wedge  41 , the wedge  42  and the wedge  43  located at the upper portions of the side face of the concentrated winding  12 , the second wedge group includes the wedge  44 , the wedge  45 , and the wedge  46  located at the lower portions of the side face of the concentrated winding  12 , and the wedges are staggered along an axial direction of the stator. Further, each of the wedge  41 , the wedge  42 , the wedge  43 , the wedge  44 , the wedge  45 , and the wedge  46  may be embodied as a trapezoidal-shaped wedge. As described above, the gap between the adjacent two concentrated windings  11 ,  12  is the trapezoidal-shaped gap, thus the trapezoidal-shaped wedge can be in plane contact with the concentrated winding  11  and the concentrated winding  12 , and via the plane contact, forces applied onto the concentrated winding  11  and the concentrated winding  12  may be uniform. Furthermore, for extending the length of the first ventilation path, heights of the trapezoidal-shaped wedges are required to be slightly greater than or slightly smaller than half of a depth of the trapezoidal-shaped slot. It should be understood by the person skilled in the field that, an extent of being slightly smaller or slightly greater than half of the depth of the trapezoidal-shaped slot in this embodiment of the present application refers to an extent on condition that the length of the first ventilation path can be extended. Furthermore, the first ventilation path may specifically be of a curved shape, an up-down fluctuated shape, a wave shape, or a curvilinear shape etc., and the specific shapes are not limited by the embodiments of the present application, as long as the length of the first ventilation path can be extended. Further, a dimension of the height of the trapezoidal-shaped wedge is not strictly limited in the embodiments of the present application. 
         [0024]    Moreover, the number of the wedges included in the first wedge group and the second wedge group according to the embodiment of the present application is not limited to the number listed above. It should be understood by the person skilled in the art that, wedges of a corresponding number may be provided according to an axial length of the electric machine and the practical ventilation requirements, for example, the first wedge group and the second wedge group may both include only one wedge. 
         [0025]    Alternatively, only the first wedge group (for example, the wedge  41 , the wedge  42 , the wedge  43 , these are referred to as upper wedges) are provided on the entire upper portion at the gap between windings of the concentrated winding  12 , or only the second wedge group (for example, the wedge  44 , the wedge  45 , the wedge  46 , these are referred to as lower wedges) are provided on the entire lower portion at the gap between the windings of the concentrated winding  12 , thus a ventilation path is formed by the entire upper portion or the entire lower portion at the gap between the windings. Alternatively, one upper wedge and one lower wedge are fitted in each of the gaps at two end portions of the concentrated winding only, or only one upper wedge or one lower wedge is fitted in each of the gaps at two ends of the concentrated winding respectively, and the first ventilation path can be formed as long as there is a certain gap between the wedges. It should be understood by the person skilled in the art that, the specific distribution of the wedges is not limited by the embodiments according to the present application. Alternatively, at least two wedges are fitted at a center portion of the gap between the windings of the concentrated winding  12 , thus two up-down ventilation paths are formed at the gap, and by increasing a number of the ventilation paths, the concentrated winding can be fully cooled. 
         [0026]    Furthermore, referring to  FIG. 3  again, a slot wedge  3  is further provided in the gap formed between the concentrated winding  11  and the concentrated winding  12 . Based on the first ventilation path in  FIG. 3 , an air gap is formed between a rotor  5  and the slot wedge  3 , and a fourth ventilation path is formed by the air gap. 
         [0027]      FIG. 6  is a perspective schematic view showing the structure of a stator for an electric machine according to yet another embodiment of the present application. As shown in  FIG. 6 , based on the embodiments shown in  FIGS. 1 to 5 , the stator further includes a support  6  for supporting the stator iron core  20 , and the support  6  separates an inner cavity of the electric machine into a high pressure area and a low pressure area. Specifically, as shown in  FIG. 6 , a right side of the rotor  5  is a wheel hub side, and a left side is an electric machine room side, the stator support  6  separates the inner cavity of the electric machine into the high pressure area (the wheel hub side) and the low pressure area (the electric machine room side), thus the first ventilation path, the second ventilation path, the third ventilation path, and the fourth ventilation path are from the wheel hub side to the electric machine room side. Alternatively, if the electric machine room side is a high pressure area, and the wheel hub side is a low pressure area, the ventilation paths in the inner cavity of the electric machine may have a direction opposite to a flowing direction indicated in  FIG. 3 . 
         [0028]    An electric machine is further provided according to an embodiment of the present application, and the electric machine includes the stator for the electric machine in the embodiments in  FIGS. 1 to 6 . Further, the electric machine may include a wind driven generator. 
         [0029]      FIG. 7  is a schematic flow chart showing a ventilation and cooling method for an electric machine according to an embodiment of the present application. The ventilation and cooling method according to this embodiment of the present application can be implemented via the electric machine according to the above embodiments. As shown in  FIG. 7 , the ventilation and cooling method for the electric machine according to the embodiment of the present application includes steps  701  to  702 . 
         [0030]    In step  701 , the electric machine is separated into the high pressure area and the low pressure area by the support configured to fix the stator. 
         [0031]    In step  702 , cold air enters into the high pressure area via pipelines, cools the electric machine via the first ventilation path formed by the gap between the at least two wedges, and then enters into the low pressure area to change into hot air, 
         [0032]    In the ventilation and cooling method according to this embodiment of the present application, the first ventilation path is formed by at least two wedges in the gap formed by adjacent two concentrated windings, a length of the first ventilation path is extended, thus may effectively cool the concentrated windings, and may further facilitate improving the heat dissipating capability of the electric machine, and improving the power density of the electric machine, and reducing the effective material consumption of the electric machine, thereby decreasing the weight and cost of the electric machine. 
         [0033]    Further, based on the embodiment in the  FIG. 7 , the cold air may also cool the electric machine via the second ventilation path formed in the tooth portion and the third ventilation path formed in the yoke portion of slot base, and then enters into the low pressure area to turn into hot air. 
         [0034]    Further, based on the embodiment in the  FIG. 7 , the cold air may also cool the electric machine via the fourth ventilation path formed by the air gap between the rotor and the stator iron core, and then enters into the low pressure area to change into hot air. 
         [0035]    Further, based on the embodiment in the  FIG. 7 , the ventilation and cooling method may further include: 
         [0036]    entering the hot air into a cooling system in the electric machine room of the electric machine via pipelines to cool the hot air, and then returning the cooled air to an interior of the electric machine, thus forming an inner circulation air path. 
         [0037]    Further, based on the embodiment in  FIG. 7 , the ventilation and cooling method may further include:
       entering cold air outside the electric machine room of the electric machine into the cooling system in the electric machine room of the electric machine via pipelines, cooling the hot air in the inner circulation air path via the cooling system in the electric machine room, and then the hot air is discharged out of the electric machine room.       
 
         [0039]    In conclusion, by providing ventilation paths around or in the center of the concentrated windings in each slot, the embodiments of the present application address the technical issues that the axial ventilation and cooling technology cannot meet the heat dissipating capability requirement of the electric machine in the conventional technology. Besides, the cold air enters into the high pressure area in the interior of the electric machine via pipelines, and the cold air cools the electric machine via the ventilation and cooling path in the slot between the rotor and the stator iron core (first ventilation path), the ventilation and cooling path in the tooth portion (second ventilation path), the ventilation and cooling path in the yoke portion of slot base (third ventilation path), and the ventilation and cooling path in the air gap (fourth ventilation path), and then enters into the low pressure area to be turned into hot air, and then the hot air enters into the cooling system inside the electric machine room to be cooled and returns to the interior of the electric machine, thus forming a complete inner circulation air path, and effectively cooling the a heating source of the electric machine (concentrated windings). Compared with a water cooling system, and an open radial forced ventilation and cooling, the reliability of the electric machine according to the embodiments of the present application may be higher, thus may further meet the heat dissipating capability requirements of a large-sized permanent magnet machine. 
         [0040]    The embodiments described hereinabove are only specific embodiments of the present application, and should not be interpreted as limitation to the protection scope of the present application. It is obvious for those skilled in the art to make variations or replacements within the technical scope of the present application, and these variations or replacements are also deemed to fall into the scope of the present application. Therefore, the scope of the present application is defined by the claims.