Patent Publication Number: US-2023155434-A1

Title: Stator coil

Description:
This application is based on and claims the benefit of priority from Japanese Patent Application No. 2021-186935, 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 technique in which a continuous coil having three phases, a U-phase, a V-phase and a W-phase, is inserted into slots of a stator core to arrange coils of the respective phases along a circumferential direction of the stator core has been known (see, for example, Patent Document 1). 
     Patent Document 1: Japanese Patent No. 5915151 
     SUMMARY OF THE INVENTION 
     In the conventional coil above, linear portions of a coil of each phase, which are inserted in slots, are arranged side by side in units of two slots adjacent to each other in the circumferential direction of the stator core. Therefore, when this coil is mounted on the stator core by being wound in a plurality of layers, linear portions of a same phase are disposed in such a manner as to be concentrated on the adjacent two slots. In the stator thus obtained, the U-phase, the V-phase and the W-phase shift from one to another in order on a two slot-by-two slot basis along the circumferential direction. 
     However, a rotating electrical machine including such a stator has the problem of large torque variation among the phases during rotor rotation, causing rotating torque unevenness to easily occur. 
     An object of the present invention is to provide a stator coil that can eliminate rotating torque unevenness by curbing torque variation among phases during rotor rotation and thus enables provision of a high-quality rotating electrical machine. 
     (1) A stator coil according to the present invention is a stator coil (for example, a later-described stator coil  3 ,  3 A,  3 B) including a continuous three-phase coil group (for example, a later-described three-phase coil group  310 ) including a linear portion group (for example, a later-described linear portion group  314 ) in which linear portions (for example, later-described linear portions  311 ) are arranged side by side in units of two adjacent slots of slots (for example, later-described slots  22 ) of a stator core (for example, a later-described stator core  2 ) for each of three phases (for example, a U-phase, a V-phase and a W-phase, which will be described later), the linear portions in the linear portion groups of the respective phases being arranged side by side in order in the continuous three-phase coil group, the stator coil being mounted on the stator core by being wound in a plurality of layers along a circumferential direction (for example, a later-described circumferential direction Y) of the stator core, wherein in each of first slots (for example, later-described first slots  22 A) that are every other slots from among the slots of the stator core, the linear portions of a same phase are accommodated in order and stacked in a radial direction (for example, a later-described radial direction Z) of the stator core, and in each of second slots (for example, later-described second slots  22 E) that are every other slots different from the first slots from among the slots of the stator core, the linear portions of two phases that are same as two phases of the linear portions in the first slots on opposite sides of the second slot are accommodated in a number of layers stacked, the number being equal to a number of layers stacked in the first slots, and stacked in the radial direction of the stator core. 
     (2) In the stator coil according to (1) above, in a part corresponding to a boundary portion (for example, a later-described boundary portion  310   c ) between a first half portion (for example, a later-described outer circumferential-side coil group  310   a ) and a second half portion (for example, a later-described inner circumferential-side coil group  310   b ) of a number of turns of the three-phase coil group around the stator core, a pitch of each of the linear portion groups may be one slot longer or shorter than a basic pitch (for example, a later-described six-slot pitch) of each of the linear portion groups in another part. 
     (3) In the stator coil according to (1) above, a long pitch portion (for example, later-described long pitch portions Pa) in which a pitch of each of the linear portion groups is one slot longer than a basic pitch (for example, a later-described six-slot pitch) and a short pitch portion (for example, later-described short pitch portions Pb) in which the pitch of each of the linear portion groups is one slot shorter than the basic pitch may alternately be disposed over an entirety in a longitudinal direction of the three-phase coil group. 
     (4) In the stator coil according to (1) above, in a winding portion (for example, a later-described second turn) at a center in the radial direction of the stator core in a number of turns of the three-phase coil group around the stator core, a long pitch portion (for example, later-described long pitch portions Pa) in which a pitch of each of the linear portion groups is one slot longer than a basic pitch (for example, a later-described six-slot, pitch) and a short pitch portion (for example, later-described short pitch portions Pb) in which the pitch of each of the linear portion groups is one slot shorter than the basic pitch may alternately be disposed in a longitudinal direction of the three-phase coil, group, and in another winding portion (for example, later-described first and third turns), the pitch of each of the linear portion groups may be the basic pitch. 
     According to (1) above, the linear portions of any two phases of the three phases are disposed in mixture in every other slots of the stator core, and thus, torque variation among the phases during rotor rotation is curbed, enabling eliminating rotating torque unevenness. Therefore, use of the stator coil enables provision of a high-quality rotating electrical machine. 
     According to (2) above, in the part corresponding to the boundary portion between the first half portion and the second half portion of the number of turns of the three-phase coil group, merely increasing or decreasing the pitch of each of the linear portion groups by one slot relative to the basic pitch enables easily obtaining a stator coil in which linear portions of any two phases of three phases can be disposed in mixture in every other slots of a stator core. 
     According to (3) above, the long pitch portion in which the pitch of each of the linear portion groups is one slot longer than the basic pitch and the short pitch portion in which the pitch of each of the linear portion groups is one slot shorter than the basic pitch are alternately disposed over the entirety in the longitudinal direction of the three-phase coil group, enabling easily obtaining a stator coil in which linear portions of any two phases of three phases can be disposed in well-balanced mixture in every other slots of a stator core irrespective of the number of layers stacked in a radial direction of the stator core. 
     According to (4) above, in the winding portion at the center in the radial direction of the stator core, the long pitch portion in which the pitch of each of the linear portion groups is one slot longer than the basic pitch and the short pitch portion in which the pitch of each of the linear portion groups is one slot shorter than the basic pitch are alternately disposed in the longitudinal direction of the three-phase coil group, and in another winding portion, the pitch of each of the linear portion groups is the basic pitch, enabling easily obtaining a stator coil in which linear portions of any two phases of three phases can be disposed in well-balanced mixture in every other slots of a stator core irrespective of the number of layers stacked in a radial direction of the stator core. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view illustrating a stator; 
         FIG.  2    is a front view illustrating a stator coil according to a first embodiment; 
         FIG.  3    is a front view illustrating a part of a coil of one phase of the stator coil; 
         FIG.  4    is a plan view schematically illustrating the stator coil according to the first embodiment that is wound in four turns on a stator core; 
         FIG.  5    is a diagram illustrating a basic pitch of the stator coil; 
         FIG.  6    is a diagram illustrating a relationship between linear portions and slots where a pitch of the stator coil is one slot longer than the basic pitch; 
         FIG.  7    is a diagram illustrating the linear portions of the stator coil according to the first embodiment that are inserted in the slots; 
         FIG.  8    is a diagram illustrating a relationship between the linear portions and the slots where the pitch of the stator coil is one slot shorter than the basic pitch; 
         FIG.  9    is a front view illustrating a stator coil according to a second embodiment; 
         FIG.  10    is a plan view schematically illustrating the stator coil according to the second embodiment that is wound in three turns around a stator core; 
         FIG.  11    is a diagram illustrating linear portions of the stator coil according to the second embodiment that are inserted in slots; 
         FIG.  12    is a front view illustrating a stator coil according to a third embodiment; and 
         FIG.  13    is a diagram illustrating linear portions of the stator coil according to the third embodiment that are inserted in slots. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention will be described in detail below with reference to the drawings.  FIG.  1    is a perspective view of a stator  1 . The stator  1  includes a stator core  2  and a stator coil  3 . 
     The stator core  2  is formed in an annular shape including an axial hole  21  at a center, the axial hole  21  extending through the stator core  2  in an axial direction X, by a plurality of magnetic steel sheets stacked in the axial direction. On the inner circumferential side of the stator core  2 , a plurality of slots  22  are arranged radially in a circumferential direction Y of the stator core  2 . Each slot  22  is what is called an open slot and extends through the stator core  2  in the axial direction X of the stator core  2  and opens in a radial direction Z of the stator core  2  toward the axial hole  21 . Although the stator core  2  indicated in the present embodiment includes  72  slots  22 , the number of slots  22  is not limited. A rotating electrical, machine is configured by a non-illustrated rotor being rotatably disposed in the axial hole  21  of the stator core  2 . 
     The stator coil  3  is inserted into the slots  22  from the axial hole  21  side of the stator core  2  and is wound in a plurality of turns in the circumferential direction Y of the stator core  2 . consequently, the stator coil  3  is stacked in a plurality of layers in the radial direction Z of the stator core  2  and mounted. 
       FIG.  2    is a plan view illustrating the stator coil  3  according to the first embodiment. The stator coil  3  is configured by wave-winding coils each formed by a linear conductor formed of, e.g., copper being consecutively bent along the circumferential direction Y of the stator core  2  and thus shaped into a wavelike form. When the continuous wave-winding coils  31  are set in the slots  22  of the stator core  2 , the continuous wave-winding coils  31  have no need for a technique for forming each coil in such a manner that the coil is divided in a plurality of segments and welding ends of the coil segments after the coil is inserted in slots, which is a main stream method on the general public, and thus, have no needs for, for example, using high-purity copper for the coils so that the coils can endure thermal processing of welding parts. Therefore, use of recycled copper material containing impurities becomes possible, which enables contribution to achievement of cyclic use of resources. In addition, the wave-winding coils  31  require no welding, enabling reduction in weight of the coils and thus enabling reduction in weight of a rotating electrical machine using the coils. Where the rotating electrical machine is mounted in a hybrid vehicle, weight of the vehicle is reduced, enabling carbon dioxide reduction and thus enabling reduction of an adverse effect on the global environment. 
     The stator coil  3  includes a plurality of wave-winding coils  31  of three phases, a U-phase, a V-phase and a W-phase. A pair of wave-winding coils  31  (U1, U2, V1, V2, W1, W2) is provided for each of the respective phases. Therefore, the stator coil  3  is formed of a total of six continuous wave-winding coils  31  of the three phases, the U-phase, the V-phase and the W-phase. In  FIG.  2   , only two wave-winding coils  31 ,  31  of a same phase from among the six wave-winding coils  31  are indicated in bold. 
       FIG.  3    is a front view illustrating parts of two wave-winding coils  31  forming one phase of the stator coil  3 . Each of the wave-winding coils  31  includes a plurality of linear portions  311  extending in the axial direction X, which are inserted into slots  22  of the stator core  2 , coil end portions  312 ,  312  that alternately join one end portions of two adjacent linear portions  311 ,  311  to each other and other end portions of two adjacent linear portions  311 ,  311  to each other in a mountain-like shape, and terminals  313 ,  313  at opposite edge portions, which serve as an input terminal and an output terminal. In the wave-winding coils  31 ,  31  illustrated in  FIG.  3   , only the terminals  313  on the one edge portion side of the terminals  313 ,  313  of the opposite edge portions are illustrated. 
     The plurality of linear portions  311  of each of the wave-winding coils  31  extend linearly along the axial direction X of the stator core  2  and are arranged in parallel along the circumferential direction Y of the stator core  2  with a predetermined distance from one another. The respective linear portions  311 ,  311  of the two wave-winding coils  31 ,  31  forming one phase are arranged side by side with respective positions shifted from each other in the circumferential direction Y by a distance corresponding to a distance between two slots  22 ,  22  that are adjacent to each other in the circumferential direction Y of the stator core  2 . The plurality of linear portions  311  in the two wave-winding coils  31 ,  31  of one phase form a linear portion group  314  of the phase. 
     The wave-winding coils  31  of three phases, the U-phase, the V-phase and the W-phase, have a same configuration except where respective linear portion groups  314  have different pitches as described later. The stator coil  3  is formed by arranging side by side two wave-winding coils  31  (U1, U2, V1, V2, W1, W2) for each phase in parallel to each other with respective positions shifted from each other in the circumferential direction Y. The stator coil  3  is configured by a continuous three-phase coil group  310  in which the linear portions  311  in the respective linear portion groups  314  of the total of six wave-winding coils  31  of the three phases are arranged, side by side in order in the circumferential direction Y. 
     The three-phase coil group  310  is folded back at a center portion in a longitudinal direction along the circumferential direction Y of the stator core  2  in such a manner that the terminals  313 ,  313  at the opposite edge portions become close to each other. As a result, of the three-phase coil group  310  being folded back, the linear portions  311 ,  311  are stacked in two layers in the radial direction Z of the stator core  2 . As illustrated in  FIG.  2   , the twelve terminals  313  of the six wave-winding coils  31  are arranged at one edge portion in the longitudinal direction of the three-phase coil group  310  with a constant distance from one another. 
     A length in the longitudinal direction of the folded-back three-phase coil group  310  is a length enough for the three-phase coil group  310  to be mounted in four turns in the slots  22  of the stator core  2 . Therefore, as illustrated in  FIG.  4   , the stator coil  3  is wound in four turns with the linear portions  311  inserted in the respective slots  22 , along the circumferential direction Y of the stator core  2 . Consequently/ as illustrated in  FIG.  7    referred to later, in each slot  22  of the stator core  2 , linear portions  311  of eight layers (two layers×four turns) are stacked along the radial direction Z. 
     Here, as illustrated in  FIG.  2   , in the three-phase coil group  310 , in a part corresponding to a boundary portion  310   c  between an outer circumferential-side coil group  310   a  corresponding to two turns forming a first half portion of the number of turns around the stator core  2  and an inner circumferential-side coil group  310   b  corresponding to two turns forming a second half portion of the number of turns, a pitch of linear portions  311  in the linear portion group  314  is set to be one slot longer than a basic pitch of linear portions  311  in other parts of the linear portion group  314 . In more detail, while the pitch of linear portions  311  in the linear portion group  314  of each phase of the outer circumferential-side coil group  310   a  and the inner circumferential-side coil group  310   b  is set to be the basic pitch, the pitch of linear portions  311  in the linear portion group  314  of each phase at the part corresponding to the boundary portion  310   c  is set to be the basic pitch plus one slot. 
     Note that the three-phase coil group  310  of the stator coil  3  according to the first embodiment is wound in four turns around the slots  22  of the stator core  2 , and four layers of linear portions  311  are stacked on each of the outer circumferential side and the inner circumferential side in the radial direction Z of the slots  22 . Therefore, the boundary portion  310   c  is a part in which a total of twelve linear portions  311  of the respective linear portion groups  314  of the wave-winding coils  31  of the three phases and coil end portions  312  at one part (one set) corresponding to a point of transition of the turn between two turns of the outer circumferential-side coil group  310   a  and two turns of the inner circumferential-side coil group  310   b  are arranged side by side. 
     The basic pitch will be described with reference to  FIG.  5   .  FIG.  5    illustrates two adjacent linear portions  311 ,  311  and coil end portions  312 ,  312  of two wave-winding coils  31 ,  31  of one phase. In the stator coil  3 , the basic pitch is set to a six-slot (6-SLOT) pitch. In other words, adjacent linear portions  311 ,  311  of a same wave-winding coil  31  is inserted into every sixth slots  22 . Five slots  22  are disposed between linear portions  311 ,  311  adjacent to each other in the circumferential direction Y of the stator core  2  in a same wave-winding coil  31 . Linear portions  311 ,  311  arranged side by side in two wave-winding coils  31 ,  31  forming one phase are inserted into adjacent slots  22 ,  22 , respectively. 
       FIG.  6    illustrate a case where the pitch is one slot longer than the basic pitch. In other words, in the wave-winding coil  1 , each of pitches of linear portions  311 ,  311  in the part corresponding to the boundary portion  310   c  is set to a seven-slot (7-SLOT) pitch. In other words, adjacent, linear portions  311 ,  311  of a same wave-winding coil  31  are inserted into every seventh slots  22 . Six slots  22  are disposed between linear portions  311 ,  311  adjacent to each other in the circumferential direction Y of the stator core  2  in a same wave-winding coil  31 . Linear portions  311 ,  311  arranged side by side in two wave-winding coils  31 ,  31  of one phase are inserted into adjacent slots  22 ,  22 , respectively. The coil end portions  312  are stretched to a length corresponding to seven slots in the circumferential direction Y of the stator core  2  relative to the coil end portions  312  of the basic pitch illustrated in  FIG.  5   . 
       FIG.  7    illustrates the linear portions  311  in the slots  22  when the stator coil  3  according to the first embodiment, which is illustrated in  FIG.  2   , is wound in four turns around the stator core  2 . In the stator coil  3 , in each of the outer circumferential-side coil group  310   a  of two turns forming the first half portion and the inner circumferential-side coil group  310   b  of two turns forming the second half portion, linear portions  311  of a same phase are stacked in order on a four layer-by-four layer basis in each slot  22 . However, because the pitch of linear portions  311  in the parts of the linear portion groups  314 , the parts corresponding to the boundary portion  310   c  between the outer circumferential-side coil group  310   a  and the inner circumferential-side coil group  310   b  is a seven-slot pitch that is one slot longer than the basic pitch, the phases of the linear portions  311  of the four-layers in the outer circumferential-side coil group  310   a  and the phases of the linear portions  311  of the four layers of the inner circumferential-side coil group  310   b are shifted from each other by one slot in the circumferential direction Y of the stator core  2 . 
     More specifically, on the inner circumferential side of a slot  22  in which four layers of linear portions  311  of a U1-phase in the outer circumferential-side coil group  310   a  are stacked, four layers of linear portions  311  of a W2-phase in the inner circumferential-side coil group  310   b are stacked. On the inner circumferential side of a slot  22  in which four layers of linear portions  311  of a U2-phase in the outer circumferential-side coil group  310   a  are stacked, four layers of linear portions  311  of the U1-phase in the inner circumferential-side coil group  310   b  are stacked. On the inner circumferential side of a slot  22  in which four layers of linear portions  311  of a V1-phase in the outer circumferential-side coil group  310   a  are stacked, four layers of linear portions  311  of the U2-phase in the inner circumferential-side coil group  310   b  are stacked. On the inner circumferential side of a slot  22  in which four layers of linear portions  311  of a V2-phase in the outer circumferential-side coil group  310   a  are stacked, four layers of linear portions  311  of the V1-phase in the inner circumferential-side coil group  310   b  are stacked. On the inner circumferential side of a slot  22  in which four layers of linear portions  311  of a W1-phase in the outer circumferential-side coil group  310   a  are stacked, four layers of linear portions  311  of the V2-phase in the inner circumferential-side coil group  310   b  are stacked. On the inner circumferential side of a slot  22  in which four layers of linear portions  311  of the W2-phase in the outer circumferential-side coil group  310   a  are stacked, four layers of linear portions  311  of the W1-phase in the inner circumferential-side coil group  310   b  are stacked. Subsequently the above arrangements of the linear portions  311  are repeated along the circumferential direction Y of the stator core  2 . 
     Consequently, linear portions  311  of same phases (U1 and U2, V1 and V2, and W1 and W2) are accommodated in every other slots  22  (hereinafter referred to as “first slots  22 A”) from among the slots  22  of the stator core  2  in the order of U, V, W along the circumferential direction Y, and stacked in order in the radial direction Z of the stator core  2 , respectively. On the other hand, in each of every other slots  22  (hereinafter referred to as “second slots  22 B”) that are different from the first slots  22 A from among the slots  22  of the stator core  2 , linear portions  311  of two phases that are the same as two phases of linear portions  311  in first slots  22 A,  22 A disposed on opposite sides of the second slot  22 B are accommodated and stacked in order in the radial direction Z of the stator core  2 . The number of linear portions  311  stacked in each slot  22  is the same between the first slots  22 A and the second slots  22 B. The number of linear portions  311  in each second slot  22 B is the same among the phases. 
     In the stator  1  with the stator coil  3  mounted by being wound in the slots  22  as described, linear portions  311  of each two phases (U1, U2, V1, V2, W1, W2) are divided in halves in the radial direction Z of respective slots  22  and inserted in the slots in such a manner as to be shifted from each other by one slot in the circumferential direction Y. Therefore, it is possible to avoid an arrangement in which linear portions  311  of a same phase are concentrated in two adjacent slots  22 ,  22 . Since linear portions  311  of any two phases of the three phases are disposed in mixture in two adjacent slots  22 ,  22 , torque variation among the phases during rotor rotation is curbed and rotating torque unevenness is thus eliminated. Therefore, use of the stator  1  with the stator coil  3  mounted enables configuring a high-quality rotating electrical machine. 
     The present invention is not limited to the case where the pitch of linear portions  311  in the part of the linear portion group  314 , the part corresponding to the boundary portion  310   c,  is set to a seven-slot pitch that is one slot longer than the basic pitch that is a six-slot pitch. As illustrated in  FIG.  8   , even if the pitch of linear portions  311  in the parts of the linear portion groups  314 , the parts corresponding to the boundary portion  310   c,  is set to a five-slot pitch that is one slot shorter than the basic pitch, effects that are similar to the above can be obtained. In the case of the five-slot pitch, four slots  22  are disposed between linear portions  311 ,  311  that are adjacent to each other in the circumferential direction Y of the stator core  2  in a same wave-winding coil  31 . Coil end portions  312  are shrunk to a length corresponding to five slots along the circumferential direction Y of the stator core  2  relative to the coil end portions  312  of the basic pitch. In this case, the linear portions  311  of each two phases (U1, U2, V1, V2, W1, W2) in the inner circumferential-side coil group  310   b  are disposed in such a manner as to be shifted by one slot to the side opposite to that of  FIG.  7    in the circumferential direction Y of the stator core  2 , from the linear portions  311  of each two phases (U1, U2, V1, V2, W1, W2) in the outer circumferential-side coil group  310   a.    
     Although the stator coil  3  according to the first embodiment is configured in such a manner as to be wound in four turns around the stator core  2 , the number of turns around the stator core  2  is not limited to four. However, in the stator coil  3  according to the first embodiment, the pitch of linear portions  311  is different only in the part corresponding to the boundary portion  310   c  between the outer circumferential-side coil group  310   a  in the first half portion of the number of turns in the three-phase coil group  310  and the inner circumferential-side coil group  310   b  in the second half portion of the number of turns, and thus, if the number of turns is an odd number, the number of linear portions  311  of two different phases that are disposed in a same slot  22  is not the same between the two phases. Therefore, it is preferable that the stator coil  3  according to the first embodiment be wound in an even number of turns around the stator core  2 . 
       FIG.  9    is a plan view illustrating a stator coil  3 A according to a second embodiment. Parts provided with reference numerals that are the same as those of the stator coil  3  according to the first embodiment indicate parts that are the same as those of the first embodiment, and thus, description of such parts will be omitted below by incorporation of the above description by reference. In  FIG.  9   , also, only two wave-winding coils  31 ,  31  of a same phase from among six wave-winding coils  31  are indicated in bold. 
     As illustrated in  FIG.  9   , in a three-phase coil group  310  of the stator coil  3 A, long pitch portions Pa having a seven-slot pitch (see  FIG.  6   ) obtained by increasing a pitch of linear portions  311  in each linear portion group  314  by one slot relative to a basic pitch (see  FIG.  5   ) that is a six-slot pitch and short pitch portions Pb having a five-slot pitch (see  FIG.  8   ) obtained by decreasing the pitch of linear portions  311  by one slot relative to the basic pitch are alternately disposed over an entirety in a longitudinal direction of the three-phase coil group  310 . All of coil end portions  312  disposed on the terminal  313  side (the upper side in  FIG.  9   ) of the three-phase coil group  310  are stretched to a length corresponding to seven slots along the circumferential direction Y of the stator core  2  relative to the coil end portions  312  in the case of the basic pitch and all of coil end portions  312  disposed on the non-terminal side (the lower side in  FIG.  9   ) of the three-phase coil group  310  are shrunk to a length corresponding to five slots along the circumferential direction Y of the stator core  2  relative to the coil end portions  312  in the case of the basic pitch. 
     The stator coil  3 A according to the second embodiment is also folded back at a center portion in the longitudinal direction of the three-phase coil group  310  and a length in the longitudinal direction of the folded-back three-phase coil group  310  is a length enough for the three-phase coil group  310  to be mounted in three turns in slots  22  of the stator core  2 . Therefore, as illustrated in  FIG.  10   , the stator coil  3 A is wound in three turns along the circumferential direction Y while the linear portions  311  being inserted in the respective slots  22  of the stator core  2 . Consequently, as illustrated in  FIG.  11   , six layers (two layers×three turns) of the linear portions  311  are stacked in a radial direction Z in each slot  22  of the stator core  2 . 
     Since in the stator coil  3 A, the long pitch portions Pa having a seven-slot pitch and the short pitch portions Pb having a five-slot pitch are alternately disposed along the longitudinal direction of the three-phase coil group  310 , as illustrated in  FIG.  11   , six layers of linear portions  311  of phases that are the same (U1, U2, V1, V2, W1, W2) are accommodated and stacked in the radial direction Z in each first slot  22 A. The linear portions  311  of phases that are the same (U1 and U2, V1 and V2, W1 and W2), the linear portions corresponding to six layers, are alternately disposed in the radial direction Z. More specifically, in each first slot  22 A, three linear portions  311  of U1 and three linear portions  311  of U2 in a U-phase are alternately stacked in the radial direction Z, three linear portions  311  of V1 and three linear portions  311  of V2 in a V-phase are alternately stacked in the radial direction Z, or three linear portions  311  of W1 and three linear portions  311  of W2 in a W-phase are alternately stacked in the radial direction Z. 
     On the other hand, in each second slots  22 B, linear portions  311  of two phases that are the same as two phases of linear portions  311  in first slots  22 A on opposite sides of the second slot  223  are accommodated and stacked in the radial direction Z of the stator core  2 . The linear portions  311  of two phases, the linear portions corresponding to six layers, in each second slot  22 B are alternately disposed in the radial direction Z. More specifically, where the U-phase and the V-phase are provided in first slots  22 A,  22 A disposed on opposite sides of a second slot  22 B, three linear portions  311  of V1 in the V-phase and three linear portions  311  of U2 in the U-phase are alternately stacked in the radial direction Z in the second slot  22   b.  Where the V-phase and the W-phase are provided in first slots  22 A,  22 A disposed on opposite sides of a second slot  22 B, three linear portions  311  of W1 in the W-phase and three linear portions  311  of V2 in the V-phase are alternately stacked in the radial direction Z in the second slot  22 B. Where the W-phase and the U-phase are provided in first slots  22 A,  22 A disposed on opposite sides of a second slot  22 B, three linear portions  311  of U1 in the U-phase and three linear portions  311  of W2 in the W-phase are alternately stacked in the radial direction Z in the second slot  22 B. Note that the number of linear portions  311  stacked in each slot  22  is the same between the first slots  22 A and the second slots  22 B. The number of linear portions  311  in each second slot  22 B is the same among the phases. 
     In a stator  1  with the stator coil  3 A mounted by being wound in the slots  22  as described above, as illustrated in  FIG.  11   , the linear portions  311  of each two phases (U1, U2, V1, V2, W1, W2) are inserted in the radial direction Z of respective slots in such a manner as to be shifted in the circumferential direction Y in a well-balanced manner. Therefore, it is possible to avoid an arrangement in which linear portions  311  of a same phase are concentrated in two adjacent slots  22 ,  22 . Since linear portions  311  of any two phases of the three phases are disposed in mixture in two adjacent slots  22 ,  22 , torque variation among the phases during rotor rotation is curbed and rotating torque unevenness is thus eliminated. Therefore, use of the stator  1  with the stator coil  3 A mounted enables configurating a high-quality rotating electrical machine. 
     Although the stator coil  3 A according to the second embodiment is configured in such a manner as to be wound in three turns around the stator core  2 , the number of turns around the stator core  2  is not limited to three. In addition, the number of turns around the stator core  2  of the stator coil  3 A according to the second embodiment enables linear portions  311  of two phases to be disposed in a well-balanced manner in each second slot  22 B irrespective of whether the number of turns is an even number or an odd number. 
       FIG.  12    is a plan view illustrating a stator coil  3 B according to a third embodiment. Farts provided with reference numerals that are the same as those of the stator coil  3  according to the first embodiment indicate parts that are the same as those of the first embodiment, and thus, description of such parts will be omitted below by incorporation of the above description by reference. In  FIG.  12   , also, only two wave-winding coils  31 ,  31  of a same phase from among six wave-winding coils  31  are indicated in bold. As with the stator coil  3 A, this stator coil  3 B is also mounted on a stator core  2  by being wound in three turns around the stator core  2 . 
     As illustrated in  FIG.  12   , in a three-phase coil group  310  Of the stator coil  38 , in a winding portion of a second turn corresponding to a center in a radial direction Z of the stator core  2  in the number of turns, three turns, of the three-phase coil group  310  around the stator core  2 , a pitch of linear portions  311  in each of linear portion groups  314  is different from a pitch of linear portions  311  in each of the linear portion groups  314  in winding portions of the other winding portions of a first turn and a third turn. 
     In other words, in the three-phase coil group  310  of the stator coil  3 B, the pitch of linear portions  311  in each of the linear portion groups  314  in the winding portion of the first turn on the most outer circumferential side and the winding portion of the third turn on the most inner circumferential side is set to a basic pitch (see  FIG.  5   ) that is a six-slot pitch. On the other hand, in the pitch of linear portions  311  in each of the linear portion groups  314  in the winding portion of the second turn, long pitch portions Pa having a seven-slot pitch (see  FIG.  6   ) that is one slot longer than the basic pitch and short pitch portions Pb having a five-slot pitch (see  FIG.  8   ) that is one slot shorter than the basic pitch are alternately disposed in a longitudinal direction of the three-phase coil group  310 . All of coil end portions  312  disposed on the terminal  313  side (the upper side in  FIG.  12   ) in the three-phase coil group  310  of the second turn are stretched to a length corresponding to seven slots along a circumferential direction Y of the stator core  2  relative to coil end portions  312  in the case of the basic pitch, and all of coil end portions  312  disposed on the non-terminal  313  side (the lower side in  FIG.  12   ) are shrunk to a length corresponding to five slots along the circumferential direction Y of the stator core  2  relative to the coil end portions  312  in the case of the basic pitch. 
     As with the stator coil  3 A, as illustrated in  FIG.  10   , the stator coil  3 B according to the third embodiment is wound in three turns along the circumferential direction Y while the linear portions  311  being inserted in the respective slots  22  of the stator core  2 . Consequently, as illustrated in  FIG.  13   , six layers (two layers×three turns) of the linear portions  311  are stacked along the radial direction Z in each of the slots  22  of the stator core  2 . 
     In the stator coil  3 B, the long pitch portions Pa having a seven-slot pitch and the short pitch portions Pb having a five-slot pitch are alternately disposed along the longitudinal direction of the three-phase coil group  310  of the second turn disposed at the center in the radial direction Z of the stator core  2 , and thus, as illustrated in  FIG.  13   , in each first slot  22 A, six layers of linear portions  311  of phases that are the same (U1, U2, V1, V2, W2, W2) are accommodated and stacked in order on a three layer-by-three layer basis in the radial direction Z. More specifically, in each first slot  22 A, three linear portions  311  of U2 and three linear portions  311  of U1 in a U-phase are stacked in order, in the radial direction Z, three linear portions  311  of V2 and three linear portions  311  of V1 in a V-phase are stacked in order in the radial direction Z, or three linear portions  311  of W2 and three linear portions  311  of W1 in a W-phase are stacked in order in the radial direction Z. 
     On the other hand, in each second slot  223 , linear portions  311  of two phases that are the same as two phases of linear portions  311  in first slots  22 A on opposite sides of the second slot  223  are accommodated and stacked in order on a three layer-by-three layer basis in the radial direction  2  of the stator core  2 . More specifically, where the U-phase and the V-phase are provided in first slots  22 A,  22 A disposed on the opposite sides of a second slot  223 , three linear portions  311  of V1 in the V-phase and three linear portion  311  of U2 in the U-phase are stacked in order in the radial direction Z in the second slot  22 B. Where the V-phase and the W-phase are provided in first slots  22 A,  22 A disposed on opposite sides of a second slot  223 , three linear portions  311  of W1 in the W-phase and three linear portions  311  of V2 in the V-phase are stacked in order in the radial direction Z in the second slot  22 B. Where the W-phase and the U-phase are provided in first slots  22 A,  22 A on opposite sides of a second slot  22 B, three linear portions  311  of U1 in the U-phase and three linear, portions  311  of W2 in the W-phase are stacked in order in the radial direction  7 , in the second slot  22 B. Note that, the number of linear portions  311  stacked in each slot  22  is the same between the first slots  22 A and the second slots  223 . The number of linear portions  311  in each second slot  22 B is the same among the phases. 
     In a stator  1  in which the stator coil  3 B is mounted by being wound in the slots  22  as described above, as illustrated in  FIG.  13   , linear portions  311  of each two phases (U1, U2, V1, V2, W1, W2) are inserted in such a manner that linear portions  311  on the outer circumferential side and linear portions  311  on the inner circumferential side are shifted from each other by one slot in the circumferential direction Y with center portions in the radial direction Z of the slots  22  as boundaries. Therefore, it is possible to avoid an arrangement in which linear portions  311  of a same phase are concentrated in two adjacent slots  22 ,  22 . Since linear portions  311  of any two phases of the three phases are disposed in mixture in two adjacent slots  22 ,  22 , torque variation among the phases during rotor rotation is curbed and rotating torque unevenness is thus eliminated. Therefore, use of the stator  1  with the stator coil  3 B mounted enables configuring a high-quality rotating electrical machine. 
     Although the stator coil  3 B according to the third embodiment is configured to be wound in three turns around the stator core  2 , as with the stator coil  3 A according to the second embodiment, the number of turns around the stator core  2  is not limited to three. However, in the stator coil  3 B according to the third embodiment, in order for the pitch of linear portions  311  in the winding portion corresponding to the center in the radial direction Z of the stator core  2  to be different from the others, the number of turns is limited to odd numbers of turns that provide a winding portion corresponding to the center in the radial direction Z of the stator core  2 . 
     As above, the present invention provides the following effects. In other words, a stator coil  3 ,  3 A,  3 B includes a continuous three-phase coil group  310  including a linear portion group  314  in which linear portions  311  are arranged side by side in units of two adjacent slots  22 ,  22  of slots of a stator core  2  for each of three phases, a U-phase, a V-phase and a W-phase, the linear portions in the linear portion groups  314  of the respective phases being arranged side by side in order in the three-phase coil group  310 , the stator coil  3 ,  3 A,  3 B being mounted on the stator core  2  by being wound in a plurality of layers along a circumferential direction Y of the stator core  2 , and in each of first slots  22 A that are every other slots from among the slots  22  of the stator core  2 , the linear portions  311  of a same phase are accommodated in order and stacked in a radial direction Z of the stator core  2 , and in each of second slots  22 B that are every other slots different from the first slots  22 A from among the slots  22  of the stator core  2 , the linear portions  311  of two phases that are the same as two phases of linear, portions  331  in the first slots  22 K,  22 A on opposite sides of the second slot  22 B are accommodated in a number of layers stacked, the number being equal to a number of layers stacked in the first slots  22 A, and stacked in the radial direction Z of the stator core  2 . Accordingly, the linear portions  311  of any two phases of the three phases are disposed in mixture in every other slots of the stator core  2 , and thus, torque variation among the phases during rotor rotation is curbed and rotating torque unevenness is thus eliminated. Therefore, use of the stator coil  3 ,  3 A,  3 B enables configurating a high-quality rotating electrical machine. 
     In the stator coil  3  according to the first embodiment, in the part corresponding to the boundary portion  310   c  between the outer circumferential-side coil group  310   a  in the first half portion of the number of turns of the three-phase coil group  310  around the stator core  2  and the inner circumferential-side coil group  310   b  in the second half portion of the number of turns, the pitch of each of the linear portion groups  314  is one slot longer or shorter than the basic pitch of each of the linear portion groups  314  in another part. Accordingly, in the part corresponding to the boundary portion  310   c  between the first, half portion and the second half portion of the number of turns of the three-phase coil group  310 , merely increasing or decreasing the pitch of each of the linear portion groups  314  by one slot relative to the basic pitch enables easily obtaining a stator coil  3  in which linear portions  311  of any two phases of the three phases can be disposed in mixture in every other slots  22  of the stator core  2 . 
     In the stator coil  3 A according to the second embodiment, the long pitch portions Pa in which the pitch of each of the linear portion groups  314  is one slot longer than the basic pitch and the short pitch portions Pb in which the pitch of each of the linear portion groups  314  is one slot shorter than the basic pitch are alternately disposed over an entirety in the longitudinal direction of the three-phase coil group  310 . Accordingly, it is possible to easily obtain a stator coil  3 A in which linear portions  311  of any two phases of three phases can be disposed in well-balanced mixture in every other slots  22  of a stator core  2  irrespective of the number of layers stacked in a radial direction Z of the stator core  2 . 
     In the stator coil  3 B according to the third embodiment, in the second turn that is the winding portion at the center in the radial direction Z of the stator core  2  in the number of turns of the three-phase coil group  310  around the stator core  2 , the long pitch portions Pa having a seven-slot pitch in which the pitch of each of the linear portion groups  314  is one slot longer than the basic pitch that is a six-slot pitch, and the short pitch portions Pb having a five-slot pitch in which the pitch of each of the linear portion groups  314  is one slot: shorter than the basic pitch are alternately disposed in the longitudinal direction of the three-phase coil group  310 , and in each of the first and third turns that are the other winding portions, the pitch of each of the linear portion groups  314  is the basic pitch. Accordingly, it is possible to easily obtain a stator coil  3 B in which linear portions  311  of any two phases of three phases can be disposed in a well-balanced mixture in every other slots  22  of a stator core  2  irrespective of the number of layers stacked in a radial direction Z of the stator core  2 . 
     EXPLANATION OF REFERENCE NUMERALS 
       2  stator core 
       22  slot 
       22 A first slot 
       22 B second slot 
       3 ,  3 A,  3 B stator coil 
       310  three-phase coil group 
       310   a  outer circumferential-side coil group (first half portion) 
       310   b  inner circumferential-side coil group (second half portion) 
       310   c  boundary portion 
       311  linear portion 
       314  linear portion group 
     Pa long pitch portion 
     Pb short pitch portion 
     y circumferential direction of stator core 
     Z radius direction of stator core