Patent Publication Number: US-2023155440-A1

Title: Stator coil

Description:
This application is based on and claims the benefit of priority from Japanese Patent Application No. 2021-186946, filed on 17 Nov. 2021, the content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a stator coil. 
     Related Art 
     Conventionally, a technology of a stator coil is known, for example, by Patent Document 1, the coil including a coil group of coils of three phases of a U-phase, a V-phase and a W-phase, which is configured by bending one end of each coil, in a state where an input terminal of one end portion of the coil and a midpoint terminal of the other end portion are closely arranged, while forming a straight portion to be inserted into slots of a stator core, and laminating forward portions and backward portions of a plurality of straight portions of the coils.
     Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2021-58076   

     SUMMARY OF THE INVENTION 
     Conventionally, as shown in  FIG.  8   , in a stator coil  200 , three input terminals  202   a ,  203   a  and  204   a  of U, V and W at one end of the coil and three midpoint terminals  202   b ,  203   b  and  204   b  of Nu, Nv and Nw at the other end are arranged in order of U, general, VJ, Nu, W, NV, general and Nw, when viewed in a slot arrangement direction of the stator core (arrangement direction of straight portions  201  of the coil). The midpoint terminals  202   b ,  203   b , and  204   b  are electrically connected to a common connection plate  205 . However, in this case, since the input terminals and the midpoint terminals of the coil end portions of respective phases are not continuously arranged, a process of forming the coil into a sheet shape is complicated, and particularly in a braided strip-shaped coil, the forming becomes difficult. 
     On the other hand, it is considered that this disadvantage of the stator coil  200  can be solved by closely arranging the input terminals  202   a ,  203   a  and  204   a  and the midpoint terminals  202   b ,  203   b  and  204   b , for example, as shown in  FIG.  9   . When the stator coil  200  is viewed in the slot arrangement direction of the stator core (arrangement direction of the straight portions  201  of the coil), the input terminals  202   a ,  203   a  and  204   a  and the midpoint terminals  202   b ,  203   b  and  204   b  are arranged in order of U, V, W, Nu, Nv and Nw. 
     However, the stator coil  200  shown in  FIG.  9    has the following problems.  FIG.  10 A  schematically shows a stator in a case where straight portions of the stator coil shown in  FIG.  9    are inserted into each of three adjacent slots  101  of a stator core  100 . A cross symbol in a circle depicted in each slot  101  indicates that an orientation of each straight portion  201  of the coil in the slot  101  (orientation of the straight portion  201  from the input terminals  202   a ,  203   a  and  204   a  toward the midpoint terminals  202   b ,  203   b  and  204   b ) is from a front side toward a back side in a perpendicular direction to a paper surface. Therefore, in the stator coil  200  of the configuration shown in  FIG.  9   , the orientations of the straight portions  201  of the three-phase coils of the U-phase, V-phase and W-phase arranged in the adjacent slots  101  are the same. In this case, an orientation of current to flow through the straight portion  201  in the slot  101  is also the same as an orientation of the straight portion  201  of the coil of each phase. However, in this case, as shown in  FIG.  10 B , the current flowing through the straight portions  201  in the adjacent slots  101  is only oriented from each input terminal (U, V, W) to the midpoint terminal (N), and hence the current has nowhere to go, so that a rotor disposed in the stator cannot be smoothly rotated. 
     Therefore, an object of the present invention is to provide a stator coil, in which coils of respective phases can be optimally arranged in slots of a stator core, and which has good formability. 
     (1) A stator coil according to the present invention is a stator coil (for example, a stator coil  1  described later) including a coil group (for example, a coil group  10  described later) of coils of three phases of a U-phase, a V-phase and a W-phase (for example, a U-phase coil  11 , a V-phase coil  12  and a W-phase coil  13  described later), each including a plurality of straight portions (for example, a plurality of straight portions,  111 ,  121  and  131  described later) inserted into slots (for example, slots  22  described later) of a stator core (for example, a stator core  20  described later), the coil group being folded back in a state where input terminals and midpoint terminals are closely arranged, so that forward portions and backward portions of the plurality of straight portions are laminated, wherein the Input terminals and the midpoint terminals of the respective three-phase coils are alternately arranged in a length direction (for example, an X-direction described later) of the stator coil. 
     According to the above (1), since the input terminal and the midpoint terminal of each of the three-phase coils are alternately arranged in the length direction of the stator coil, and hence the respective phase coils can be optimally arranged into the slots of the stator core. Since the input terminal and the midpoint terminal of the coil are continuously arranged in the length direction of the stator coil, all the coils can be simultaneously braided, and formability into a sheet shape is satisfactory. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a front view of a stator coil according to an embodiment of present invention; 
         FIG.  2    is a plan view showing a behavior in mounting the stator coil according to the embodiment of present invention in a stator core; 
         FIG.  3 A  is a plan view schematically showing a part of the stator to which a part of the stator coil according to the embodiment of present invention is mounted; 
         FIG.  3 B  is an explanatory view of an orientation of current in the stator shown in  FIG.  3 A ; 
         FIG.  4    is a plan view schematically showing a part of the stator to which the stator coil according to the embodiment of present invention is mounted; 
         FIG.  5    is a graph showing a current waveform in a case where current is supplied to each phase coil in the stator shown in  FIG.  4   ; 
         FIG.  6 A  is a view showing a phase of an S-pole and an N-pole with respect to an electrical angle of 0 degrees of the stator shown in  FIG.  4   ; 
         FIG.  6 B  is a view showing a phase of the S-pole and the N-pole with respect to an electrical angle of 30 degrees of the stator shown in  FIG.  4   ; 
         FIG.  6 C  is a view showing a phase of the S-pole and the N-pole with respect to an electrical angle of 60 degrees of the stator shown in  FIG.  4   ; 
         FIG.  6 D  is a view showing a phase of the S-pole and the N-pole with respect to an electrical angle of 90 degrees of the stator shown in  FIG.  4   ; 
         FIG.  6 E  is a view showing a phase of the S-pole and the N-pole with respect to an electrical angle of 120 degrees of the stator shown in  FIG.  4   ; 
         FIG.  6 F  is a view showing a phase of the S-pole and the N-pole with respect to an electrical angle of 150 degrees of the stator shown in  FIG.  4   ; 
         FIG.  7    is a front view showing an end portion of a stator coil according to another embodiment of present invention; 
         FIG.  8    is a front view showing an example of arrangement of input terminals and midpoint terminals of a conventional stator coil; 
         FIG.  9    is a front view showing another example of the arrangement of the input terminals and midpoint terminals of the conventional stator coil; 
         FIG.  10 A  is a plan view schematically showing a part of a stator to which the conventional stator coil shown in  FIG.  9    is mounted; and 
         FIG.  10 B  is an explanatory view of an orientation of current in a stator shown in  FIG.  10 A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, description will be made as to embodiments of the present invention with reference to the drawings.  FIG.  1    is a front view showing a stator coil  1  according to one embodiment of present invention. The stator coil  1  includes a coil group  10  including three-phase coils of a U-phase coil  11 , a V-phase coil  12  and a W-phase coil  13  and includes a sheet-like coil formed in a strip shape long in one direction (left-right direction in  FIG.  1   ). 
     In addition, an X-direction shown in  FIG.  1    indicates a length direction of the stator coil  1 . This X-direction is a direction along a circumferential direction of a stator core  20  when the stator coil  1  is mounted to the stator core  20  (see  FIG.  2   ). An X 1  direction in the X-direction indicates one side of the length direction of the stator coil  1 , and an X 2  direction indicates the other side of the length direction of the stator coil  1 .  FIG.  1    shows a Y-direction indicating a width direction of the stator coil  1 . This Y-direction corresponds to a direction along an axial direction (perpendicular direction to a paper surface of  FIG.  2   ) of the stator core  20  when the stator coil  1  is mounted to the stator core  20 . A Y 1  direction in the Y-direction indicates one side in the width direction of the stator coil  1 , and a Y 2  direction indicates the other side in the width direction of the stator coil  1 . 
     Each of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  of the present embodiment includes two coils. Specifically, the U-phase coil  11  is configured by coils  11   a  and  11   b  adjacent to each other in the X-direction. The V-phase coil  12  includes coils  12   a  and  12   b  adjacent to each other in the X-direction. The W-phase coil.  13  includes coils  13   a  and  13   b  adjacent to each other in the X-direction. 
     The U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  include straight portions  111 ,  121  and  131 , and coil end portions  112 ,  122  and  132 , respectively. 
     The straight portions  111 ,  121  and  131  are portions inserted into slots  22  of the stator core  20 . Each of the straight portions  111 ,  121  and  131  includes two portions parallel to each other for each phase. All the straight portions  111 ,  121  and  131  extend along the Y-direction and are arranged in parallel at a predetermined pitch along the X-direction. 
     The coil end portions  112 ,  122  and  132  are portions alternately connecting, in a mountain shape in the length direction, the straight portions of each phase that are parallel in the X-direction to each other, that is, end portions of the straight portions  111  and  111  of the U-phase coil  11  to each other, end portions of the straight portions  121  and  121  of the V-phase coil  12  to each other, and end portions of the straight portions  131  and  131  of the W-phase coil  13  to each other. The coil end portions  112 ,  122  and  132  protrude in a mountain shape on one side (Y 1  side) and the other side (Y 2  side) in the width direction of the stator coil  1 . 
     The coil end portions  112 ,  122  and  132  protrude from both end faces of the stator core  20  in the axial direction when the stator coil  1  is mounted in the slots  22  of the stator core  20 . The U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  have the straight portions  111 ,  121  and  131  and the mountain-shaped coil end portions  112 ,  122  and  132 , respectively, forming a continuous wave winding coil folded into a waveform. When the continuous wave winding coil is set in the slots of the stator core, the coil does not require a common mainstream technology of dividing and molding the coil into a plurality of segments and welding coil ends after inserted into slots, and hence, to cope with thermal processing of a welding portion, for example, there is no need to use a high-purity copper material for the coil. Therefore, it is also possible to use a recycled copper material containing impurities, and it is possible to contribute to achieving of recycling of resources. In addition, the wave winding coil does not have to be welded, so that a weight of the coil can be reduced, and a weight of a rotating electric machine using this coil can be reduced. When the rotating electric machine is mounted in a hybrid car, carbon dioxide emissions can be reduced by reducing a vehicle weight, and adverse effects on global environment can be reduced. 
     The U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  at one end are provided with input terminals  113   a ,  123   a  and  133   a , respectively. The input terminals  113   a ,  123   a  and  133   a  are electrically connected to two coils of each phase, that is, the coils  11   a  and  11   b ,  12   a  and  12   b , and  13   a  and  13   b , respectively. 
     The input terminals  113   a ,  123   a  and  133   a  are portions that supply power to the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13 . The input terminals  113   a ,  123   a  and  133   a  are connected to protrude from the end portions of the straight portions  111 ,  121  and  131  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  in the width direction of the stator coil  1 . Specifically, the input terminals  113   a ,  123   a  and  133   a  are diagonally inclined from the end potions of the straight portions  111 ,  121  and  131  arranged in endmost portions of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  on one end portion side, toward one side (X 1  side) of the stator coil  1  in the length direction, at the same inclination angle as in the coil end portions  112 ,  122  and  132  and are bent toward one side (Y 1  side) of the stator coil  1  in the width direction, to extend parallel to the straight portions  111 ,  121  and  131 . 
     The U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  at the other end are provided with midpoint terminals  113   b ,  123   b  and  133   b , respectively. The midpoint terminals  113   b ,  123   b  and  133   b  are portions connecting the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13 , to form respective midpoints (Nu, Nv, Nw) of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13 . The midpoint terminals  113   b ,  123   b  and  133   b  are electrically connected to two coils of each phase, that is, the coils  11   a  and  11   b ,  12   a  and  12   b , and  13   a  and  13   b , respectively. The three midpoint terminals  113   b ,  123   b  and  133   b  are electrically connected to a common connection plate  140  and are put together. 
     The midpoint terminals  113   b ,  123   b  and  133   b  are connected to protrude from the end portions of the straight portions  111 ,  121  and  131  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  in the width direction of the stator coil  1 . Specifically, the midpoint terminals  113   b ,  123   b  and  133   b  are diagonally inclined from the end potions of the straight portions  111 ,  121  and  131  arranged in endmost portions of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  on the other end portion side, toward the other side (X 2  side) of the stator coil  1  in the length direction, at the same inclination angle as in the coil end portions  112 ,  122  and  132  and are bent toward one side (Y 1  side) of the stator coil  1  in the width direction, to extend parallel to the straight portions  111 ,  121  and  131 . As will be described later, the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are folded back from the other side (X 2  side) toward one side (X 1  side), in a middle of the stator coil  1  in the length direction, and hence the midpoint terminals  113   b ,  123   b  and  133   b  after folded as shown in  FIG.  1    protrude toward one side (Y 1  side) in the width direction of the stator coil  1 , in the same arrangement form as in the input terminals  113   a ,  123   a  and  133   a.    
     In the stator coil  1 , the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  of both the end portions of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are arranged together on one side (X 1  side) of the stator coil  1  in the length direction shown in  FIG.  1   . Specifically, the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are continuously formed into the waveform along the length direction of the stator coil  1 , folded back from the other side (X 2  side) to one side (X 1  side) in the middle, and braided. When the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are folded back, the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  of the respective phases are closely arranged and arranged at the same pitch as a pitch of the straight portions  111 ,  121  and  131  of the respective phases. The U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are folded back in the middle of the length direction, so that forward portions (straight portions  111 ,  121  and  131  before folded back) and backward portions (straight portions  111 ,  121  and  131  after folded back) of the straight portions  111 ,  121  and  131  are laminated every phase. 
     Thereby, the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  are all orderly arranged to protrude in the same direction on one side (Y 1  side) of the width direction and on one side (X 1  side) of the length direction of the stator coil  1  as shown in  FIG.  1   . The laminated straight portions  111 ,  121  and  131  are oriented in the same direction as each other. The orientation of the straight portions  111 ,  121  and  131  is a direction from the input terminals  113   a ,  123   a  and  133   a  toward the midpoint terminals  113   b ,  123   b  and  133   b . Specifically, the straight portions  111 ,  121  and  131  of the same phase laminated on each other have the same orientation from one side (Y 1  side) to the other side (Y 2  side) or from the other side (Y 2  side) to one side (Y 1  side) in the width direction of the stator coil  1 . 
     Here, as shown in  FIG.  1   , the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13 , respectively, are alternately arranged at a constant pitch along the length direction of the stator coil  1 . In the present embodiment, from one side (X 1  side) toward the other side (X 2  side) in the length direction of stator coil  1 , the input terminal  113   a  of the U-phase coil  11 , the midpoint terminal  123   b  of the V-phase coil  12 , the input terminal  133   a  of the W-phase coil  13 , the midpoint terminal  113   b  of the U-phase coil  11 , the input terminal  123   a  of the V-phase coil  12  and the midpoint terminal  133   b  of the W-phase coil  13  are arranged in order (U, Nv, W, Nu, V and Nw). Therefore, also in the straight portions  111 ,  121  and  131  and the coil end portions  112 ,  122  and  132  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13 , respectively, from one side (X 1  side) toward the other side (X 2  side), the forward portion of the U-phase coil  11 , the backward portion of the V-phase coil  12 , the forward portion of the W-phase coil  13 , the backward portion of the U-phase coil  11 , the forward portion of the V-phase coil  12  and the backward portion of the W-phase coil  13  are arranged in order. 
     In the stator coil  1  formed in a form of a strip-shaped sheet in this way, as shown with arrows in  FIG.  1   , the straight portions  111 ,  121  and  131  are oriented and alternately arranged for each phase in the orientation from one side (Y 1  side) to the other side (Y 2  side) in the width direction of the stator coil  1  and the orientation from the other side (Y 2  side) to one side (Y 1  side), in order from the one side (X 1  side) toward the other side (X 2  side) in the length direction of the stator coil  1 . 
     As shown in  FIG.  2   , the stator coil  1  is mounted in the stator core  20  by inserting the straight portions  111 ,  121  and  131  into the slots  22 , respectively, from a central shaft hole  21  side of the stator core  20 . Thereby, a stator  2  is configured. The length direction of the stator coil  1  of the present embodiment has a length of four circumferences in a circumferential direction of the stator core  20 . Therefore, the stator coil  1  is wound around four circumferences and mounted in the stator core  20 . In one circumference of the stator coil  1 , since the straight portions  111 ,  121  and  131  of the forward portions and the backward portions are laminated on each other for each phase, and the stator coil  1  is wound around four circumferences of the stator core  20 , so that in each slot  22 , eight layers of the straight portions  111 ,  121  and  131  are laminated and arranged in a radial direction. 
       FIG.  3 A  schematically shows the stator  2  in a case where the straight portions  111 ,  121  and  131  of the stator coil  1  shown in  FIG.  1    are inserted into three adjacent slots  22  of the stator core  20 .  FIG.  3 A  schematically shows four layers among the eight layers of the straight portions  111 ,  121  and  131  inserted into the slots  22  with a cross symbol in a circle and a dot symbol in a circle. The cross symbol in the circle depicted in the slot  22  indicates that the straight portions  111 ,  121  and  131  of the coils in the slot  22  are oriented from a front side toward a back side in the perpendicular direction to the paper surface. The dot symbol in the circle depicted in the slot  22  indicates that the straight portions  111 ,  121  and  131  of the coils in the slot.  22  are oriented from the back side toward the front side in the perpendicular direction to the paper surface. 
     Thus, when the stator coil  1  including the configuration shown in  FIG.  1    is mounted in the stator core  20 , the orientations of the straight portions  111 ,  121  and  131  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  arranged in the adjacent slots  22  turn to an opposite orientation in any one of the three phases. In  FIG.  3 A , the orientation of the straight portion  121  of the V-phase coil  12  only turns to the opposite orientation, and the orientations of the straight portions  111 ,  121  and  131  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are arranged so that the orientations sequentially turn to the opposite orientation in the circumferential direction of the stator core  20 . Thus, when the stator coil  1  is mounted in the slots  22  of the stator core  20 , the orientation of the straight portion  121  of the V-phase coil  12  only differs with respect to an orientation of current to flow through the straight portions  111 ,  121  and  131  in the slots  22 , and hence, as shown in  FIG.  3 B , current flows toward the input terminal  123   a  of the V-phase coil  12 , so that a rotor (not shown) disposed in the shaft hole  21  of the stator core  20  can be smoothly rotated. 
       FIG.  4    schematically shows a part of the stator  2  with the stator coil  1  mounted in the stator core  20 . Cross symbols in circles and dot symbols in circles are arranged in the circumferential direction of the stator core  20 , to schematically show four layers of the straight portions  111 ,  121  and  131 . In each slot  22 , two symbols are arranged, to indicate that eight layers of the straight portions  111 ,  1 . 21  and  131  are inserted in a radial direction of the stator core  20 . In addition, four layers of the straight portions  111 ,  121  and  131  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  outside in the radial direction shift by one slot in the circumferential direction from four layers inside in the radial direction. 
       FIG.  5    shows a current waveform in a case where current is supplied to the input terminals  113   a ,  123   a  and  133   a  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  in the stator  2  shown in  FIG.  4   . A vertical axis indicates a magnitude of current and a horizontal axis shows an electrical angle. As shown in  FIG.  5   , it is seen that in the stator  2  with the stator coil  1  mounted in the stator core  20 , current of each of the phases of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  maintains each phase at an electrical angle of 120 degrees and smoothly changes in time series. 
       FIGS.  6 A to  6 F  show phases of an S-pole and an N-pole with respect to the electrical angle of the stator  2  shown in  FIG.  4   . In the drawings, cross symbols in circles and dot symbols in circles depicted in the slots  22  indicate orientations of current in a U-phase (solid circle), a V-phase (dashed circle) and a W-phase (dashed chain line circle). The cross symbols in the circles indicate that current flowing through each of the straight portions  111 ,  121  and  131  of the coils in the slots  22  is oriented from a front side toward a back side in a perpendicular direction to a paper surface. The dot symbols in the circles indicate that current flowing through each of the straight portions  111 ,  121  and  131  of the coils in the slots  22  is oriented from the back side toward the front side in the perpendicular direction to the paper surface. Also, the drawings depict a position of a magnetic pole S/N generated when current is supplied to the input terminals  113   a ,  123   a  and  133   a  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  in the stator  2  shown in  FIG.  4   . In each of  FIGS.  6 A to  6 F , a numeral outside the radial direction of the stator  2  indicates the electrical angle, and a numeral inside the radial direction indicates a phase (mechanical angle) of the S-pole. As shown in  FIGS.  6 A to  6 F , it is seen that when current is supplied to the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  of the stator coil  1 , the phase of the S-pole also smoothly moves as the electrical angle of the stator  2  progresses. 
     As described above, the stator coil  1  includes the coil group  10  including the U-phase coil  11 , the V-phase coil  12  and the W-phase coil.  13 , each including the plurality of straight portions  111 ,  121  and  131  inserted into the slots  22  of the stator core  20 , the coil group being folded back in the state where the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  are closely arranged, so that the forward portions and backward portions of the plurality of straight portions  111 ,  121  and  131  are laminated, wherein the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are alternately arranged in the length direction of the stator coil  1 , so that the coils of the respective phases can be optimally arranged into the slots  22  of the stator core  20 . Additionally, since the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  are continuously arranged in the length direction of the stator coil  1 , all the coils of the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  can be simultaneously braided, and formability into a sheet shape is satisfactory. 
     In addition, the stator coil is not limited to the coil formed by braiding the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  as shown in  FIG.  1   . For example, as in a stator coil  1 A shown in  FIG.  7   , an input terminal  123   a  and a midpoint terminal  123   b  only of a V-phase coil  12  may be arranged on an opposite end portion side to input terminals  113   a  and  133   a  and midpoint terminals  113   b  and  133   b  of a U-phase coil  11  and a W-phase coil  13 , and the U-phase coil  11 , the V-phase coil  12  and the W-phase coil  13  may be simply folded back in a middle and laminated in a state where the input terminals  113   a ,  123   a  and  133   a  and the midpoint terminals  113   b ,  123   b  and  133   b  are closely arranged. 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
           1  stator coil 
         coil group 
           11  U-phase coil 
           12  V-phase coil 
           13  W-phase coil 
         stator core 
           22  slot 
           111 ,  121  and  131  straight portion 
           113   a ,  123   a  and  133   a  input terminal 
           113   b ,  123   b  and  133   b  midpoint terminal 
         X length direction of the stator coil