Patent Publication Number: US-2023155436-A1

Title: Stator for an electric machine, drive installation for an electric vehicle, and vehicle

Description:
The present invention relates to a stator for an electric machine. The invention moreover relates to a drive installation for an electric vehicle, and to a vehicle. 
     In electrically driven vehicles, an ideally smooth delivery of torque, i.e., a delivery of torque with as few ripples as possible, is desirable in order to achieve a positive NVH (noise, vibration, harshness) behaviour. This can be achieved in particular by way of minor torque ripples and minor parasitic forces in an electric machine of the drive installation. In the case of stator windings of a stator of the electric machine, a required number of windings are to be disposed symmetrically, with a minor winding overhang, and so as to be easy to connect and in a production-friendly manner with a view to automated production with a high level of process reliability, in a stator core of the stator. 
     The invention is based on the object of specifying an option for driving a vehicle with minor torque ripples. 
     This object is achieved according to the invention by a stator for an electric machine, having a stator core which extends along a longitudinal axis, has an end side and a further end side that lies opposite the end side, and having a stator winding, wherein a multiplicity of grooves that are disposed in the circumferential direction are configured in the stator core; wherein the stator winding occupies a plurality of winding zones in the grooves; wherein the stator winding has a number of N strands and a number of 2·P poles, and the number of grooves is 2·P·N·q, where P, N and q are natural numbers and q≥2; wherein each winding zone extends across at least q+1 of the grooves; wherein each winding zone is radially subdivided into 1 st  to L th  layers which are designated according to their sequence in the radial direction; wherein the layers configure 1 st  to (L/2) th  double layers, wherein the i th  double layer comprises the (2i−1) th  and the (2i) th  layer for all 1≤i≤(L/2), where L≥6 and is even, where L and i are natural numbers; wherein a number of the double layers, being less than the number of the other double layers, is displaced by at least one groove counter to the pre-defined circumferential direction in relation to the other double layers; wherein each winding zone in the circumferential direction is subdivided into first to q th  sub-winding zones which comprise in each case all layers and are designated according to their sequence in the circumferential direction; wherein the stator winding for a respective strand has a phase winding; wherein the phase winding comprises at least one sub-winding which configures a current path and comprises internal portions that are disposed within the grooves, and connection portions that are disposed on the end sides of the stator core and in each case connect in an electrically conductive manner two internal portions which are directly successive in terms of the current path. 
     The stator according to the invention for an electric machine has a stator core. The stator core extends along the longitudinal axis. The stator core has an end side and a further end side. The further end side lies opposite the end side. The stator has a stator winding. A multiplicity of grooves are configured in the stator core. The grooves are disposed in the circumferential direction. The stator winding occupies a plurality of winding zones in the grooves. The stator winding has a number of N strands and a number of 2·P poles. The number of grooves is 2·P·N·q. P, N and q are natural numbers. q is greater than two. Each winding zone extends across at least q+1 of the grooves. Each winding zone is radially subdivided into first to L th  layers. L is greater than six and is even. The layers are designated according to their sequence in the radial direction. The layers configure first to (L/2) th  double layers. The i th  double layer comprises the (2i−1) th  and the (2i) th  layer for all 1≤i≤(L/2). L and i are natural numbers. L is greater than six and is even. A number of the double layers, being less than the number of the other double layers, is displaced by at least one groove counter to the pre-defined circumferential direction in relation to the other double layers. Each winding zone in the circumferential direction is subdivided into first to q th  sub-winding zones. The sub-winding zones comprise in each case all layers. The sub-winding zones are designated according to their sequence in the circumferential direction. The stator winding for a respective strand has a phase winding. The phase winding comprises at least one sub-winding which configures a current path. The sub-winding has internal portions that are disposed within the grooves, and connection portions that are disposed on the end sides of the stator core. The connection portions connect in each case in an electrically conductive manner two internal portions which are directly successive in terms of the current path. 
     The invention is based on the concept that in the case of the winding zones being occupied in a non-uniform manner, a more favourable NVH behaviour is achieved in one rotation direction than along the other rotation direction of the rotating rotor movement. Such a disposal of the double layers may also be referred to as a non-uniform pitch of the stator winding. Since the double layers in part are displaced along the pre-defined circumferential direction, slight torque ripple can be achieved along a rotation direction of the electric machine. In this way, particularly smooth running of the electric machine can be achieved while, at the same time, the stator winding is symmetrically disposed in the grooves. 
     The stator core is typically configured from a multiplicity of individual sheets which are disposed in a stack and/or mutually isolated. To this extent, the stator core can also be referred to as laminated stator core. The cross-sectional plane is defined in particular by the radial direction and by the circumferential direction. The radial division runs in particular on a plane that is defined by the longitudinal axis and the radial direction. 
     Each winding zone preferably extends across at least two grooves, particularly preferably across at least three grooves, or at least four groups. Portions of the stator winding that are associated with the same phase of the electric machine are typically disposed in each winding zone. 
     The number of layers can be 6, 8, 10, 12, 14 or 16. In particular, a radially outer double layer, a radially inner double layer or a radially central double layer may be displaced. 
     Each winding zone, in a cross-sectional plane that is perpendicular to the longitudinal axis, by way of a centric radial division can be subdivided into a first side and into a second side. The second side here can succeed the first side along a pre-defined circumferential direction, and each winding zone on the first side can occupy a smaller cross-sectional area of the grooves than on the second side. The division can run through the [(x+1)/2] th  groove of a respective winding zone when x is odd, and run so as to be centric between the (x/2) th  and the [(x/2)+1] th  groove of a respective winding zone when x is even, x describing the number of grooves occupied by a respective winding zone. 
     The stator winding in the drive installation according to the invention can be configured as a round-wire winding. 
     Alternatively, the stator winding can be configured as a shaped conductor winding, in particular as a hairpin winding. The stator winding in a shaped conductor winding is configured by a multiplicity of shaped conductors which configure a current path, or a plurality of current paths, for a current which for generating the rotating field passes through the stator winding. The shaped conductors can be configured from a metal rod and/or have a rectangular or radiused rectangular cross section. Each part, or one part, of the shaped conductor preferably has two straight portions which extend in the axial direction within a respective groove. The straight portions can be connected to one another by a coil end portion on a first end side of the stator core. Each straight portion on a further end side of the stator core can be adjoined by an end portion. The straight portions are preferably configured so as to be integral to the coil end portion and/or to the end portions. The end portions of two respective shaped conductors are preferably mechanically connected to one another in an electrically conductive and materially integral manner, in particular by welding, so as to configure the stator are winding. Moreover, one part of the shaped conductors, in particular for connecting the stator winding to a phase connector and/or to one or a plurality of neutral points provided shaped conductor, can have a straight portion, a connector portion on the first end side, and an end portion on the further end side. 
     A straight portion of one of the shaped conductors can be disposed in each layer. The internal portions can be configured by the straight portions of the shaped conductors. The connection portions on the first end side can be configured by the end coil portions of the shaped conductors. The connection portions on the further end side can be configured by the connected end portions of two different shaped conductors. 
     The stator winding can have a neutral point. The at least one sub-winding of a respective strand can be wired so as to form the neutral point. The stator winding can also have two neutral points and a plurality of sub-windings for each strand. In this instance, one of the sub-windings of a respective strand can be wired so as to form one of the neutral points, and another one of the sub-windings of a respective strand can be wired so as to form the other of the neutral points. 
     According to one first variant of design embodiment, the sub-winding can comprise a plurality of conductor sequences of internal portions which are successive in terms of the current path; wherein each conductor sequence is disposed in one of the double layers and configures a full encirclement of the stator core. In this way, a wave winding can be configured as a stator winding. 
     It is also preferable for first to L/2 th  of the conductor sequences to run in each case along a circumferential direction, in particular along the pre-defined circumferential direction, wherein [(L/2)+1] th  to L th  of the conductor sequences run in each case along a further circumferential direction that is counter to the circumferential direction. The wave winding can be wound in the opposite direction as a result. 
     In a refinement it can be provided that each conductor sequence which directly succeeds another conductor sequence in terms of the current path is disposed in a different sub-winding zone than the other conductor sequence. 
     In the first variant of design embodiment it is furthermore preferable for a further sub-winding, which corresponds to the sub-winding, to be provided; wherein a respective internal portion of the further sub-winding that lies in the same layer of the same winding zone as an internal portion of the sub-winding, is disposed in a different sub-winding zone than the sub-winding zone in which the internal portion of the sub-winding lies. To this extent, the sub-winding can also be referred to as the first sub-winding, and the further sub-winding can be referred to as the second sub-winding. 
     A second and a third variant of design embodiment will be described hereunder. 
     In order for a combined loop/wave winding to be formed in the second and the third variant of design embodiment, it can be provided that one of the at least one sub-winding comprises a set of first to P th  conductor sequences of the first type that are successive in the sequence of their designation in terms of the current path and are in each case disposed in first to fourth directly adjacent winding zones for the same strand. Each conductor sequence of the first type preferably comprises first to (L/2) th  pairs of one first of the internal portions and one second of the internal portions, wherein the pairs are designated according to their sequence along the current path. The first and the second internal portions can be disposed in different layers of the same double layer. It is preferable here for the first pair to be disposed in the first double layer, wherein the second pair is disposed in the (L/2) th  double layer, wherein the third pair is disposed in the second double layer, or the third to (L/2) th  pairs are disposed in the second to [(L/2)−1] th  double layer. The third winding zone, in which the internal portions of the first to (P−1) th  conductor sequences is disposed, can be the first winding zone in which the conductor sequence that succeeds the conductor sequence in terms of the current path is disposed. The fourth winding zone, in which the internal portions of the first to (P−1) th  conductor sequences are disposed, can be the second winding zone in which the conductor sequence that succeeds the conductor sequence in terms of the current path is disposed. This sub-winding can also be referred to as the first sub-winding. 
     Alternatively or additionally, it can be provided in the second and the third variant of design embodiment that one of the at least one sub-winding comprises a set of first to P th  conductor sequences of the second type that are successive in the sequence of their designation in terms of the current path and are in each case disposed in two directly adjacent winding zones for the same strand. It is preferably provided that each conductor sequence of the second type comprises first to (L/2) th  pairs of one first of the internal portions and one second of the internal portions, and the pairs are designated according to their sequence along the current path. The first and the second internal portions here can be disposed in different layers of the double layer corresponding to the designation of the pair. It is preferably provided that the first to (P−1) th  conductor sequences of the second type by way of one of the connection portions are connected to the succeeding conductor sequence of the second type along the current path, and the succeeding conductor sequence of the second type is disposed in two directly adjacent winding zones for the same strand. This sub-winding can also be referred to as the second sub-winding. 
     The sub-windings preferably run about the stator core in opposite circumferential directions. 
     In the second variant of design embodiment it can be provided that the first internal portion of the pairs of the conductor sequences of the or of a respective sub-winding is disposed in one of the layers of the double layer, and the second internal portion of the pairs of the conductor sequences of the or of a respective sub-winding is disposed in the other one of the layers of the double layer. 
     In the third variant of design embodiment, the first internal portion of the pairs with an odd-numbered designation of the conductor sequences of the or of a respective sub-winding can be disposed in one of the layers of the double layer; the second internal portion of the pairs with an odd-numbered designation of the conductor sequences of the or of a respective sub-winding can be disposed in the other layer of the double layer; the first internal portion of the pairs with an even-numbered designation of the conductor sequences of the or of a respective sub-winding can be disposed in the other layer of the double layer; and the second internal portion of the pairs with an even-numbered designation of the conductor sequences of the or of a respective sub-winding can be disposed in the one layer of the double layer. 
     In a preferred design embodiment it can furthermore be provided that the or a respective sub-winding comprises in total q sets of the conductor sequences which are in each case disposed in the same sub-winding zone; wherein each set that directly succeeds another set of the same sub-winding in terms of the current path, is disposed in a different sub-winding zone than the other set. 
     The object on which the invention is based is furthermore achieved by a drive installation for an electric vehicle, having: a stator according to the invention, wherein the stator is specified for generating a rotating magnetic field; a converter installation for converting magnetic energy of the rotating field into a rotating output movement of the drive installation; wherein the converter installation has a rotor which conjointly with the stator configures a rotating electric machine such that the rotor is able to be set in a rotating rotor movement which as a function of the rotating field is able to be selectively set to one of two opposite rotation directions; and a transmission portion which is specified for transmitting the rotating rotor movement to the rotating output movement, wherein the converter installation as the preferred rotation direction has one of the two rotation directions of the rotating rotor movement, wherein the preferred rotation direction corresponds to the pre-defined circumferential direction. 
     The rotor can be permanently excited or not permanently excited. The rotor can be separately excited. The rotor can be magnetically excited or voltage-excited. The transmission portion is in particular also specified to convert the rotating rotor movement into the rotating output movement. The rotation directions of the rotating rotor movement can also be understood to be orientations of the rotating rotor movement so that the preferred rotation direction corresponds to a preferred orientation. 
     The preferred rotation direction may be pre-defined in various ways. In general, a presence of the preferred rotation direction of the rotating rotor movement can initiate the vehicle to travel forward, and a presence of the other rotation direction of the rotating rotor movement can initiate the vehicle to travel in reverse. 
     It is possible for an efficiency of the transmission portion in the preferred rotation direction to be higher than in the other rotation direction. In other words, the transmission portion can be specified in such a manner that the transmission of the rotating rotor movement to the rotating output movement in the presence of the preferred rotation direction is more efficient than in the presence of the other rotation direction of the rotating rotor movement. For example, mechanical losses of the transmission portion are less in the presence of the preferred rotation direction than in the presence of the other rotation direction. 
     It can also be provided that the transmission portion has a gearbox having an asymmetrical design embodiment that determines the preferred rotation direction. For example, a respective tooth of mutually meshing gear wheels of the gearbox can thus be of an asymmetrical configuration. 
     The drive installation can furthermore have a control installation for the transmission portion, which for the preferred rotation direction has a larger number of selectable operating modes than for the other one of the rotation directions. A larger number of operating modes can thus be provided for the forward travel than for the travel in reverse. 
     It is also possible for the drive installation to have a ventilation installation which in the preferred rotation direction has a higher cooling efficiency than in the other one of the rotation directions. For example, the higher cooling efficiency can be derived from the position of an air intake, the latter in the presence of the preferred rotation direction receiving headwind. 
     The object on which the invention is based is furthermore achieved by a vehicle comprising a drive installation according to the invention, which is specified for driving the vehicle. 
     The preferred rotation direction may also be pre-defined by an installed position of the drive installation in a vehicle body. The rotating output movement preferably acts on an axle and/or on wheels of the vehicle. 
     A winding zone contains only parts of the stator winding of the same strand, i.e. U, V or W. 
    
    
     
       Further advantages and details of the present invention are derived from the exemplary embodiments described hereunder as well as by means of the drawings. The latter are schematic illustrations in which: 
         FIG.  1    shows a diagram of an exemplary embodiment of the vehicle according to the invention, having a first exemplary embodiment of the drive installation according to the invention; 
         FIG.  2    shows a perspective view of a first exemplary embodiment of a stator according to the invention; 
         FIG.  3    shows a schematic diagram of the stator winding disposed in the stator core, according to the first exemplary embodiment; 
         FIG.  4    shows a schematic diagram of a winding zone in the grooves, according to the first exemplary embodiment; 
         FIG.  5    shows a block circuit diagram of the stator winding according to the first exemplary embodiment; 
         FIG.  6    shows a schematic winding diagram of a phase of the stator winding, according to the first exemplary embodiment; 
         FIG.  7    shows a block circuit diagram of the stator winding of the stator according to the invention, according to a second exemplary embodiment; 
         FIG.  8    shows a schematic winding diagram of a phase of the stator winding, according to the second exemplary embodiment; 
         FIG.  9    shows a block circuit diagram of the stator winding of the stator according to the invention, according to a third exemplary embodiment; and 
         FIG.  10    shows a schematic winding diagram of a phase of the stator winding according to the third exemplary embodiment. 
     
    
    
       FIG.  1    shows a schematic diagram of an exemplary embodiment of a vehicle  1 , having a first exemplary embodiment of a drive installation  2 . 
     The drive installation  2  has a stator  3  which is specified to generate a rotating magnetic field. Moreover, the drive installation  2  has a converter installation  4  for converting magnetic energy of the rotating field into a rotating output movement  5  of the drive installation  2 . 
     The converter installation  4  has a rotor  6  which conjointly with the stator  3  configures a rotating electric machine  7  so that the rotor  6  can be set in a rotating rotor movement  8 . Moreover, the converter installation  4  has a transmission portion  9  which is specified for transmitting and converting the rotating rotor movement  8  into the rotating output movement  5 . 
     The transmission portion  9  has one of two rotation directions of the rotating rotor movement  8  as the preferred rotation direction  10 . The latter is derived in particular in that an efficiency of the transmission portion  9  is higher in the preferred rotation direction  10  than in the other one of the rotation directions. Accordingly, the transmission portion  9  is specified in such a manner, for example, that the transmission of the rotating rotor movement  8  to the rotating output movement  5  is more efficient in the presence of the rotation direction  10  than in the presence of the other rotation direction of the rotating rotor movement  8 . 
     The preferred rotation direction  10  can also be derived in that the transmission portion  7  has a gearbox  11  having an asymmetrical design embodiment that defines the rotation direction  9 . To this end, the respective tooth of mutually meshing gear wheels  12  of the gearbox  11  can be of an asymmetrical configuration. Likewise, the preferred rotation direction  9  can be derived in that the drive installation  2  has a control installation  13  for the transmission portion  9 , that for the preferred rotation direction  10  has a larger number of selectable operating modes than for the other one of the rotation directions. In this way, a larger number of operating modes can be provided for the forward travel of the vehicle  1  than for the travel in reverse of said vehicle  1 . Furthermore, the preferred rotation direction  9  can be derived in that the drive installation  2  has a ventilation installation  14  which in the preferred rotation direction  10  has a higher cooling efficiency than in the other one of the rotation directions. Moreover, the preferred rotation direction  10  can also be derived from an installed position of the drive installation  2  in the vehicle  1 . 
     As is furthermore shown in  FIG.  1   , the rotating rotor movement  8  by way of a shaft  15  of the drive installation  2  acts on the transmission portion  9 . The rotating output movement  5  by way of an axle  16  of the vehicle  1  acts on the wheels  17  on of the latter. 
     The stator  3  corresponds to one of the exemplary embodiments described hereunder. 
       FIG.  2    shows a perspective view of a stator  3  according to the first exemplary embodiment. 
     The stator  3  has a stator core  20  which extends along a longitudinal axis  21  and in which a multiplicity of grooves  22  disposed in the circumferential direction are configured. The stator core  20  here in an exemplary manner surrounds a receptacle space  23  for the rotor  6  (see  FIG.  1   ) and has a first end side  24  and a second end side  25  lying opposite said first end side  24 . Moreover, the stator  3  has a stator winding  26 . 
       FIG.  3    shows a schematic diagram of the stator winding  26  disposed in the stator core  20 . 
     The stator winding occupies a plurality of windings zones  27  in the grooves  22 . Each winding zone here in a cross-sectional plane that is perpendicular to the longitudinal axis  21  (see  FIG.  2   ) and corresponds to the plane of the drawing in  FIG.  3   , is subdivided by a centric radial division  28  into a first side  29  and into a second side  30 . In the present exemplary embodiment, each winding zone  27  in an exemplary manner extends across three grooves  22  such that the division  28  runs so as to be centric through the second of the three grooves  22  of the winding zone  27 . 
     The second side  30  along the preferred rotation direction  10  is successive to the first side  29 . As can be seen, each winding zone  27  on the first side  29  occupies a smaller cross-sectional area of the grooves  22  that on the second side  30 . 
     It can furthermore be seen in  FIG.  3    that the stator winding  26  has N=3 strands U, V, W for a respective phase of the electric machine  7  (see  FIG.  1   ). Each winding zone  27  contains only proportions of the stator winding  26  of the same strand U, V, W. A hole count q of the stator winding  26  in the present exemplary embodiment is two. Each winding zone  27  presently extends across a number of grooves  22 , said number being q+1. Moreover, each winding zone  27  is sub-divided into first to qth sub-winding zones  31   a ,  31   b , specifically into a first sub-winding zone  31   a  and into a second sub-winding zone  31   b.    
       FIG.  4    shows a schematic diagram of a winding zone  27  in the grooves  22 . 
     Each winding zone  27 , which in  FIG.  3    is identified by a hatched area, is radially sub-divided into first to sixth (L th ) layers  32   a - f , the latter being designated according to their sequence in the radial direction from radially outside to radially inside. The layers  32   a - f  form first to third [(L/2) th ] double layers  33   a - d , wherein the i th  double layer comprises the (2i−1) th  and the (2i) th  layer for all 1≤i≤(L/2). Accordingly, the first double layer  33   a  comprises the first layer  32   a  and the second layer  32   b , the second double layer  33   b  comprises the third layer  32   c  and the fourth layer  32   d , and the third double layer  33   c  comprises the fifth layer  32   e  and the sixth layer  32   f . A double layer  33   a , presently the radially outermost double layer  33   a , is displaced by a groove  22  counter to the preferred rotation direction  10  in relation to the other double layers  33   b ,  33   c  counter to the preferred rotation direction. 
       FIG.  5    shows a block circuit diagram of the stator winding  26  according to the first exemplary embodiment. 
     The stator winding  23  for each strand U, V, W has a phase winding  34   u ,  34   v ,  34   w . Each phase winding  34   u ,  34   v ,  34   w  comprises a first sub-winding  35   a  and a second sub-winding  35   b , which in each case configure a current path. Each sub-winding  35   a ,  35   b  comprises a number, corresponding to the number of layers L, of conductor sequences  36   a - f  which are connected in series. 
     Each phase winding  34   u ,  34   v ,  34   w  is connected to a phase connector  37 . The phase windings  34   u ,  34   v ,  34   w  are furthermore wired so as to form two neutral points  38   a ,  38   b , wherein the first sub-windings  35   a  are wired so as to form the first neutral point  38 , and the second sub-windings  35   b  are wired so as to form the second neutral point  38   b . The phase connectors  37  and the neutral points  38   a ,  38   b  are also illustrated in  FIG.  2   . 
       FIG.  6    shows a winding diagram of a phase U of the stator winding  26  according to the first exemplary embodiment. 
     The stator winding  26  has 2·P=10 poles, N=3 phases and a hole count q=2. The number of grooves  22  is 2·P·N·q=60. A groove numbering from 1 to 60 is indicated in  FIG.  6   . Each sub-winding  35   a ,  35   b  comprises the internal portions  39  that are disposed within the grooves  22 , and connection portions  40 ,  41  that are disposed on the end sides  24 ,  25  of the stator core  20  (cf.  FIG.  2   ), and connect in each case in an electrically conductive manner two directly successive internal portions  39  in terms of the current path. The connection portions  40  here are situated on the second end side  25 , and the connection portions  41  are situated on the first end side  24 . The connection portions  40  are illustrated by solid lines, and the connection portions  41  are illustrated by dashed lines, in  FIG.  6   . 
     The stator winding  26  is configured as a wave winding. The conductor sequences  36   a - f  are in each case configured by a plurality of successive internal portions  39  that are connected in series by the connection portions  40 ,  41 . In the first exemplary embodiment, each conductor sequence  36   a - f  configures a complete encirclement about the stator core  20  in the circumferential direction. The first to third (L/2 th ) conductor sequences  36   a - c  here run in each case along the preferred rotation direction  10 , and the fourth to sixth conductor sequences  36   c - f  run in each case counter to the first to third conductor sequences  36   a - c , thus counter to the preferred rotation direction  10 . Each conductor sequence  36   a - f  is disposed in one of the double layers  33   a - c . Each conductor sequence  36   b - f  which directly succeeds another conductor sequence  36   a - e  in terms of the current path, is disposed in a different sub-winding zone  31   a ,  31   b  than the other conductor sequence  36   a - e . The conductor sequences  36   a - f  as a result are disposed in an alternating manner in different sub-winding zones  31   a ,  31   b.    
     The second sub-winding  35   b  to this extent corresponds to the first sub-winding  35   a . In the second sub-winding  35   b , a respective internal portion  39  which lies in the same layer  32   a - f  of the same winding zone  27  as an internal portion  39  of the first sub-winding  35   a , is disposed in a different sub-winding zone  31   a ,  31   b  than the sub-winding zone  31   a ,  31   b  in which the internal portion  39  of the first sub-winding  35   a  lies. 
     In both sub-windings  35   a ,  35   b , the internal portions  39 , which are connected directly by a connection portion  40 ,  41  and are associated with the same conductor sequence  36   a - f , are mutually spaced apart by q·N=6 grooves. 
     In the first sub-winding  35   a , the internal portion  39  of the first conductor sequence  36   a  and the internal portion  39  of the second conductor sequence  36   b , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N=6 grooves. The internal portion  39  of the second conductor sequence  36   b  and the internal portion  39  of the third conductor sequence  36   c , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N+1=7 grooves. The internal portion  39  of the third conductor sequence  36   c  and the internal portion  39  of the fourth conductor sequence  36   d , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N−1=5 grooves. The internal portion  39  of the fourth conductor sequence  36   d  and the internal portion  39  of the fifth conductor sequence  36   e , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N−1=5 grooves. The internal portion  39  of the fifth conductor sequence  36   e  and the internal portion  39  of the sixth conductor sequence  36   f , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N+2=8 grooves. 
     In the second sub-winding  35   b , the internal portion  39  of the first conductor sequence  36   a  and the internal portion  39  of the second conductor sequence  36   b , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N+2=8 grooves. The internal portion  39  of the second conductor sequence  36   b  and the internal portion  39  of the third conductor sequence  36   c , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N−1=5 grooves. The internal portion  39  of the third conductor sequence  36   c  and the internal portion  39  of the fourth conductor sequence  36   d , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N+1=7 grooves. The internal portion  39  of the fourth conductor sequence  36   d  and the internal portion  39  of the fifth conductor sequence  36   e , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N+1=7 grooves. The internal portion  39  of the fifth conductor sequence  36   e  and the internal portion  39  of the sixth conductor sequence  36   f , which is connected directly to the former by a connection portion  41 , are mutually spaced apart by q·N=6 grooves. 
     As can furthermore be derived from  FIG.  6   , the first conductor sequences  36   a  of the sub-windings  35   a ,  35   b  are connected to the phase connector  37 . The sixth conductor sequences  36   f  of the sub-windings  35   a ,  35   b  are connected to the neutral points  38   a ,  38   b , wherein the sixth conductor sequence  36   f  of the first sub-winding  35   a  here is connected to the first neutral point  38   a , and the sixth conductor sequence  36   f  of the second sub-winding  35   b  is connected to the second neutral point  38   b.    
     The phase windings  34   v ,  34   w  of the strands V, W correspond to the previously described phase winding  34   u  of the strand U, and are disposed in relation to the strand U so as to be displaced by q·N=6 grooves in the circumferential direction. 
     With reference to  FIG.  2   , the stator winding  26  by way of a multiplicity of shaped conductors  42  is configured as a hairpin winding. The shaped conductors  42  are configured from a metal rod and have a rectangular or radiused rectangular cross section. One part of the shaped conductors  42  has two straight portions  43 ,  44  which extend in the axial direction within a respective groove  22  and configure the internal portions  39 . The straight portions  43 ,  44  on a first end side  24  of the stator core  20  are connected to one another by way of an end coil portion  45 , the latter configuring the connection portion  40   b . The end coil portion  45  is configured so as to be integral to the straight portions  43 ,  44 . On a second end side  25  of the stator core  20 , each straight portion  43 ,  44  is adjoined by an end portion  46 . The end portions  46  of two respective shaped conductors  42  are mechanically connected to one another in electrically conductive and materially integral manner, in particular by welding. Two end portions  46  that are connected to one another configure a connection portion  40   a  on the second end side  25 . The shaped conductors, which are not illustrated in detail and are connected to one of the phase connectors  37 , or one of the neutral points  38   a ,  38   b , respectively, have only one straight portion and one end portion, the latter conjointly with the end portion  46  of a shaped conductor that has two straight portions  43 ,  44  configuring a connection portion  40   a  on the second end side  25 . 
       FIG.  7    shows a block circuit diagram of the stator winding  26  according to a second exemplary embodiment of a stator  3 . With the exception of the variances described hereunder, all embodiments pertaining to the further exemplary embodiment can be applied to the second exemplary embodiment. Identical or functionally equivalent components are provided with identical reference signs. 
     In the second exemplary embodiment, the stator winding  26  is a combined wave/loop winding. The stator winding  26  comprises the first sub-winding  35   a  of a respective phase winding  34   u ,  34   v ,  34   w  a first set  50   a  of first to fourth (P th ) conductor sequences of the first type  51   a - d  that are successive in the sequence of their designation in terms of the current path. Moreover, the first sub-winding  35   a  comprises a second set  50   b  of first to fourth (P th ) conductor sequences of the first type  51   a - d.    
     The second sub-winding  35   b  of the respective phase winding  34   u ,  34   v ,  34   w  comprises a first set  52   a  of first to fourth (P th ) conductor sequences of the second type  53   a - d  that are successive in the sequence of their designation in terms of the current path. Moreover, the second sub-winding  35   b  comprises a second set  52   b  of first to fourth (P th ) conductor sequences of the second type  53   a - d.    
     The number of sets  50   a ,  50   b ,  52   a ,  52   b  of a respective sub-winding  35   a ,  35   b  here corresponds to the hole count q. 
       FIG.  8    shows a winding diagram of a phase U of the stator winding  26  according to the second exemplary embodiment. 
     The stator winding  26  according to the second exemplary embodiment has 2·P=8 poles, and accordingly has 48 grooves  22 . 
     Each conductor sequence of the first type  51   a - d  is disposed in first to fourth directly adjacent winding zones  27   a - d  for the same strand U, and comprises first to third [(L/2) th ] pairs  54   a - c  of one first internal portion  39   a  and one second internal portion  39   b . The pairs  54   a - c  are designated according to their sequence along the current path. 
     The first internal portions  39   a  and the second internal portions  39   b  are disposed in different layers  32   a - f  of the same double layer  33   a - c . The first pair  54   a  is disposed in the first double layer  33   a , the second pair  54   b  is disposed in the third [(L/2) th ] double layer  33   c , and the third pair  54   c  is disposed in the second double layer  33   b . In general terms, the third to (L/2) th  pairs are disposed in the second to [(L/2)−1] th  double layer. 
     The third winding zone  27   c , in which the internal portions  39   a ,  39   b  of the first to third conductor sequences of the first type  51   a - c  [(P−1) th ] are disposed, is the first winding zone  27   a  in which the conductor sequence  51   b - d  which succeeds the conductor sequence of the first type  51   a - c  in terms of the current path is disposed. Accordingly, the fourth winding zone  27   d , in which the internal portions  39   a ,  39   b  of the first to third [(P−1) th ] conductor sequences of the first type  51   a - c  are disposed, is the second winding zone  27   b  in which the conductor sequence of the first type  51   b - d , which succeeds the conductor sequence of the first type  51   a - c  in terms of the current path, is disposed. 
     Each conductor sequence of the second type  53   a - d  is disposed in two directly adjacent winding zones  27   e ,  27   f  for the same strand U, and comprises first to third [(L/2) th ] pairs  54   d - f  of one first internal portion  39   c  and one second internal portion  39   d . The pairs  54   d - f  are designated according to their sequence along the current path. 
     The first and second internal portions  39   c ,  39   d  are disposed in different layers  32   a - f  of the double layer  33   a - c , the latter corresponding to the designation of the pair  54   d - f . The first to third [(P−1) th ] conductor sequences of the second type  53   a - c  by way of one of the connection portions  40   b  are connected to the conductor sequence of the second type  53   b - d  which succeeds along the current path. The succeeding conductor sequence of the second type  53   b - d  is disposed in two directly adjacent winding zones  27  for the same strand U. 
     The first and second sub-windings  35   a ,  35   b  run about the stator core  20  in opposite circumferential directions, wherein the second sub-winding  35   b  runs along the preferred rotation direction  10 . 
     In the second exemplary embodiment, the first internal portion  39   a ,  39   c  of the pairs  54   a - f  is disposed in one of the layers  32   a - f  of the double layer  33   a - c , and the second internal portion  39   b ,  39   d  of the pairs  54   a - f  is disposed in the other layer  32   a - f  of the double layer. 
       FIG.  9    shows a block circuit diagram of the stator winding  26  according to a third exemplary embodiment of a stator  3 . With the exception of the variances described hereunder, all embodiments pertaining to the second exemplary embodiment can be applied to the third exemplary embodiment. Identical or functionally equivalent components are provided with identical reference signs. 
     In the third exemplary embodiment, the first sub-winding  35   a  additionally has a third set  50   c  of conductor sequences of the first type  51   a - d , and the second sub-winding  35   b  additionally has a third set  52   c  of conductor sequences of the second type  53   a - d , wherein the conductor sequences  51   a - d ,  53   a - d  are not illustrated for the sake of clarity in  FIG.  9   . 
       FIG.  10    shows a winding diagram of a phase U of the stator winding  26  according to the third exemplary embodiment. 
     The stator winding  26  according to the third exemplary embodiment, like the second exemplary embodiment, has 2·P=8 poles, but a hole count q=3. Accordingly, the number of grooves  22  is 72. It can be derived from the increase in the hole count q that each of the third sets  50   c ,  52   c  are provided. 
     In the third exemplary embodiment, the first internal portion  39   a ,  39   c  of the pairs  54   a ,  54   c ,  54   d ,  54   f  with an odd-numbered designation of the conductor sequences  51   a - d ,  53   a - d  of a respective sub-winding  35   a ,  35   b  is disposed in one of the layers  32   a - f  of the double layer  33   a - c , and the second internal portion  39   b ,  39   d  of the pairs  54   a ,  54   c ,  54   d ,  54   f  with an odd-numbered designation of the conductor sequences  51   a - d ,  53   a - d  of the respective sub-winding  35   a ,  35   b  is disposed in the other layer of the double layer  33   a - c . The first internal portion  39   a ,  39   c  of the pairs  54   b ,  54   e  with an even-numbered designation of the conductor sequences  51   a - d ,  54   a - d  of the respective sub-winding  35   a ,  35   b  is disposed in the other layer  39   b ,  39   d  of the double layer  33   a - c , and the second internal portion  39   b ,  39   d  of the pairs  54 ,  54   e  with an even-numbered designation of the conductor sequences  51   a - d ,  53   a - d  of the respective sub-winding  35   a ,  35   b  is disposed in the one layer  32   a - f  of the double layer  33   a - c.    
     In the third exemplary embodiment, the second double layer  33   b  in relation to the first double layer  33   a  and the third double layer  33   c  is moreover displaced counter to the preferred rotation direction  10 . 
     According to further embodiments, which correspond in each case to one of the embodiments described above, the stator winding  26  is not configured as a hairpin winding but as a round-wire winding. 
     According to further embodiments, which correspond in each case to one of the embodiments described above, the number of poles is greater or less, wherein the number of the conductor sequences increases or reduces correspondingly. 
     According to further embodiments, which correspond in each case to one of the embodiments described above, the stator winding  26  has only one neutral point for all of the sub-windings  35   a ,  35   b.