Patent Publication Number: US-2023163649-A1

Title: Stator and rotary electric apparatus comprising same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2020/005069, filed on Apr. 16, 2020, the contents of which are all hereby incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a stator capable of allowing a current to flow in a balanced manner in a parallel circuit and a rotary electric apparatus having the same. 
     BACKGROUND ART 
     A drive motor used as a power source for an eco-friendly vehicle includes a stator that generates a magnetic flux, a rotor that is disposed with a predetermined gap inside the stator to perform a rotational movement, and a permanent magnet provided in the rotor. 
     The stator includes a stator coil disposed with a plurality of slots on an inner peripheral side of a stator core, and stator coils wound in the slots. When an alternating current is applied to the stator coil, a rotating magnetic field is generated in the stator, and a rotating torque is generated in the rotor by the rotating magnetic field. 
     A hairpin-type motor winding method may be classified into a lap winding in which a circuit is configured in a parallel structure, a wave winding in which a circuit is configured in a series structure, and a lap-winding and wave-winding mixed winding with parallel and series structures according to a shape in which the coil is wound. 
     Meanwhile, in order to minimize a loss of the motor, the coils of each phase may be configured to be divided into parallel circuits. 
     The coils of the parallel circuits may be configured to be divided into the same number of conductors for each slot or for each layer. 
     However, in the related art, as the number of parallel circuits increases, there is a problem in that connection wiring becomes more complicated. 
     In addition, when a current flowing in each parallel circuit is configured to be unbalanced, the motor winding in the related art has the following problems. 
     First, an amount of interlinkage magnetic flux in a coil of each parallel circuit is varied. 
     Second, there is a problem in that a difference in impedance occurs for each coil of each parallel circuit. This problem becomes more pronounced as the speed increases. 
     Third, there is a problem in that a coil is damaged due to a heat generation phenomenon in the coil due to a current flowing in a biased manner to any one parallel circuit. 
     Fourth, motor control may be controlled only when a current flows equally in a parallel circuit for each phase, but when an unbalanced current flows, a problem occurs in that it is difficult to control. Such a problem occurs conspicuously in a high-speed region. 
     Fifth, the magnitude of a current is related to a torque, and when an unbalanced current flows, the torque is also generated in an unbalanced manner, resulting in electromagnetic noise and vibration. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     An aspect of the present disclosure is to provide a stator for a rotary electric apparatus having a simple wiring structure that allows a current to flow in each parallel circuit in a balanced manner even when the number of parallel circuits increases, thereby solving problems such as a heat generation phenomenon in a specific coil. 
     Solution to Problem 
     In order to achieve the objectives, a stator may include a stator core in which a plurality of slots for each pole and each phase are disposed to pass therethrough in an axial direction; a stator coil wound around the stator core by connecting a plurality of conductors accommodated in the plurality of slots; a first layer to an N-th layer extending from an innermost side to an outermost side of the slot in a radial direction to accommodate the plurality of conductors, respectively, wherein the stator coil is configured with a plurality of parallel circuits for each pole and each phase, and the plurality of parallel circuits are configured to include a plurality of first conductors that constitute one of two parallel circuits, which are paired with each other, both sides of which are alternately accommodated in two slots, respectively, to be spaced apart at different slot pitches along a circumferential direction of the stator core and connected to one another; and a plurality of second conductors that constitute the other one of the two parallel circuits, both sides of which are alternately accommodated in two slots, respectively, at different slot pitch intervals along the circumferential direction and connected to one another. 
     According to an example associated with the present disclosure, the first conductor and the second conductor may be connected in parallel to constitute a pair at a 1-slot pitch interval from each other in a circumferential direction, wherein both sides of the first conductor are connected to be spaced apart by alternating a preset first slot pitch interval and a second slot pitch interval that is a 2-slot pitch shorter than the first slot pitch interval, and both sides of the second conductor are connected to be spaced apart by alternating the second slot pitch interval and the first slot pitch interval. 
     According to an example associated with the present disclosure, the first slot pitch may be a 7-slot pitch, and the second slot pitch may be a 5-slot pitch. 
     According to an example associated with the present disclosure, the first conductor and the second conductor may be respectively provided in plurality and connected in series, and a plurality of the first conductors or a plurality of the second conductors may be spaced apart from each other at a 6-slot pitch interval. 
     According to an example associated with the present disclosure, the first conductor and the second conductor may be wound through two slots for each pole and each phase. 
     According to an example associated with the present disclosure, both sides of each of the plurality of conductors may be accommodated in and connected to different slots and different layers. 
     According to an example associated with the present disclosure, both sides of each of the plurality of conductors may be respectively accommodated in and connected to two different layers having a difference of one layer from each other in different slots. 
     According to an example associated with the present disclosure, the stator core may be configured with 8 poles, 48 slots, and 8 layers. 
     According to an example associated with the present disclosure, an even number of parallel circuits may be provided. 
     According to an example associated with the present disclosure, the parallel circuit may be configured with four parallel circuits, wherein a first and a second parallel circuit, which are paired with each other, among the four parallel circuits, are drawn in from an outermost N-th layer and are drawn out to an innermost first layer, and a third parallel circuit and a fourth parallel circuit, which are paired with each other, among the four parallel circuits, are drawn in from the first layer and are drawn out to the N-th layer. 
     According to an example associated with the present disclosure, two parallel circuits, which are paired with each other, among the plurality of parallel circuits may be respectively wound around the same layer in different slots, wherein the first conductor and the second conductor are respectively spaced apart from each other at a predetermined slot pitch interval along a circumferential direction, and both sides of each of the first conductor and the second conductor are accommodated in two radially adjacent layers of two different slots, respectively, extended in a diagonal direction between the circumferential direction and the radial direction, and connected by moving two layers in the radial direction for every one rotation in the circumferential direction. 
     According to an example associated with the present disclosure, each of the plurality of conductors, both sides of which are disposed to be inserted into the two different slots, may be configured as a hairpin type having the same shape for each layer. 
     According to an example associated with the present disclosure, each of the plurality of conductors may include a plurality of insertion portions respectively inserted into the two slots; a crossover portion connecting one end of each of the plurality of insertion portions; a plurality of bending portions extending to protrude from the other end of each of the plurality of insertion portions to an outside of the slot, and being primarily bent; and a conductive portion that is secondarily bent at each of the plurality of bending portions to electrically connect both end portions of the conductor. 
     According to an example associated with the present disclosure, a crossover portion of each of the first conductor and the second conductor may extend in a diagonal direction between the circumferential direction and the radial direction. 
     According to an example associated with the present disclosure, respective bending portions of the first conductor and the second conductor may be bent in directions crossing each other. 
     According to an example associated with the present disclosure, the plurality of parallel circuits may be configured to include a first parallel circuit and a second parallel circuit drawn in to an outermost N-th layer of the slot, and drawn out from an innermost first layer of the slot, and wound in a first circumferential direction while constituting a pair; and a third parallel circuit and a fourth parallel circuit drawn in to the innermost first layer of the slot, and drawn out from the outermost N-th layer of the slot, and wound in a second circumferential direction opposite to the first circumferential direction while constituting another pair. 
     A rotary electric apparatus according to the present disclosure may include a housing; a stator accommodated into the housing; and a rotor mounted at inside of the stator to be rotatable with respect to the stator, wherein the stator includes a stator core in which a plurality of slots for each pole and each phase are disposed to pass therethrough in an axial direction; a stator coil wound around the stator core by connecting a plurality of conductors accommodated in the plurality of slots; and a first layer to an N-th layer extending from an innermost side to an outermost side of the slot in a radial direction to accommodate the plurality of conductors, respectively, wherein the stator coil is configured with a plurality of parallel circuits for each pole and each phase, and the plurality of parallel circuits are configured to include a plurality of first conductors that constitute one of two parallel circuits, which are paired with each other, both sides of which are alternately accommodated in two slots, respectively, to be spaced apart at different slot pitches along a circumferential direction of the stator core and connected to one another; and a plurality of second conductors that constitute the other one of the two parallel circuits, both sides of which are alternately accommodated in two slots, respectively, at different slot pitch intervals along the circumferential direction and connected to one another. 
     Advantageous Effects of Invention 
     The effects of a stator and a rotary electric apparatus having the same according to the present disclosure will be described as follows. 
     First, a plurality of conductors constituting each of a plurality of parallel circuits may be configured with two types of hairpin-type conductors having different slot pitches, that is, a long slot pitch and a short slot pitch, and the two types of hairpin-type conductors may be alternately arranged along a circumferential direction in all layers, and wired in directions crossing each other, thereby allowing the plurality of conductors constituting each parallel circuit to be evenly distributed in all slots and layers to constitute a balanced parallel circuit. 
     Therefore, according to the present disclosure, in a balanced parallel circuit, an amount of interlinkage magnetic flux of each parallel circuit may be the same, and a current may flow in a balanced manner along a plurality of parallel circuits. 
     Second, an impedance of each parallel circuit may be defined uniformly. 
     Third, a current may flow evenly to each parallel circuit, thereby solving a problem in that a heat generation phenomenon of a specific coil occurs due to the bias of the current. 
     Fourth, a current may flow evenly in each parallel circuit, thereby facilitating control during a high-speed operation. 
     Fifth, a current may flow in a balanced manner in each parallel circuit to evenly generate a torque in each parallel circuit, thereby minimizing electromagnetic noise and vibration. 
     Sixth, two types of hairpin-type coils having a long slot pitch and a short slot pitch may be applicable to all layers to reduce the number of types of hairpins, thereby improving productivity and reducing manufacturing cost. 
     Seventh, the two types of hairpin-type conductors having a long slot pitch and a short slot pitch may be identically used for each layer, thereby simplifying the structure of a coil. 
     Eighth, a lead wire (lead line) into which a current is drawn, a neutral wire (neutral line) from which the current is drawn, and a jumper wire connecting two conductors located in different layers may be arranged in any one of four quarters of the stator divided along a circumferential direction of the stator. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a conceptual view showing a rotary electric apparatus of an 8-pole, 48-slot, 8-layer model according to the present disclosure. 
         FIG.  2    is a plan view showing the rotary electric apparatus of  FIG.  1    as viewed from above. 
         FIG.  3    is a bottom view showing the rotary electric apparatus of  FIG.  1    as viewed from below. 
         FIG.  4    is a conceptual view showing the shape of hairpin type conductors that are identically configured for each layer of the stator coil of  FIG.  1   . 
         FIG.  5    is a cross-sectional view showing a shape in which a plurality of conductors  124  are accommodated in two slots  113  for each pole and each phase. 
         FIG.  6    is a conceptual view showing a wiring structure of four parallel circuits for a U-phase according to the present disclosure. 
         FIG.  7    is a conceptual view showing a wiring structure of a plurality of parallel circuits for each layer for a U-phase according to the present disclosure. 
         FIG.  8    is a conceptual view showing a wiring diagram of first and second parallel circuits for a U-phase according to the present disclosure. 
         FIG.  9    is a conceptual view showing a wiring diagram of third and fourth parallel circuits for a U-phase according to the present disclosure. 
         FIG.  10    is a graph of a waveform showing an amount of interlinkage magnetic flux of an unbalanced parallel circuit in the related art. 
         FIG.  11    is a graph of a waveform showing an amount of interlinkage magnetic flux of a balanced parallel circuit in the present disclosure. 
     
    
    
     MODE FOR THE INVENTION 
     Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings, and the same or similar elements are designated with the same numeral references regardless of the numerals in the drawings and a redundant description thereof will be omitted. A suffix “module” and “unit” used for constituent elements disclosed in the following description is merely intended for easy description of the specification, and the suffix itself does not give any special meaning or function. In describing an embodiment disclosed herein, moreover, the detailed description will be omitted when specific description for publicly known technologies to which the invention pertains is judged to obscure the gist of the present disclosure. Also, it should be understood that the accompanying drawings are merely illustrated to easily explain the concept of the invention, and therefore, they should not be construed to limit the technological concept disclosed herein by the accompanying drawings, and the concept of the present disclosure should be construed as being extended to all modifications, equivalents, and substitutes included in the concept and technological scope of the invention. 
     The terms including an ordinal number such as first, second, etc. can be used to describe various elements, but the elements should not be limited by those terms. The terms are used merely for the purpose to distinguish one element from another element. 
     In a case where an element is “connected” or “linked” to the other element, it may be directly connected or linked to the other element, but another element may exist therebetween. On the contrary, in a case where an element is “directly connected” or “directly linked” to another element, it should be understood that any other element does not exist therebetween. 
     A singular representation may include a plural representation as far as it represents a definitely different meaning from the context. 
     Terms “include” or “has” used herein should be understood that they are intended to indicate the existence of a feature, a number, a step, a constituent element, a component or a combination thereof disclosed in the specification, and it may also be understood that the existence or additional possibility of one or more other features, numbers, steps, constituent elements, components or combinations thereof are not excluded in advance. 
       FIG.  1    is a conceptual view showing a rotary electric apparatus of an 8-pole, 48-slot, 8-layer model according to the present disclosure. 
       FIG.  2    is a plan view showing the rotary electric apparatus of  FIG.  1    as viewed from above. 
       FIG.  3    is a bottom view showing the rotary electric apparatus of  FIG.  1    as viewed from below. 
       FIG.  4    is a conceptual view showing the shape of hairpin type conductors  124   a,    124   b  that are identically configured for each layer of the stator coil  120  of  FIG.  1   . 
       FIG.  5    is a cross-sectional view showing a shape in which a plurality of conductors  124  are accommodated in two slots  113  for each pole and each phase. 
       FIG.  6    is a conceptual view showing a wiring structure of four parallel circuits for a U-phase according to the present disclosure. 
     The rotary electric apparatus according to the present disclosure includes a stator  100  and a rotor  10 . 
     The stator  100  includes a stator core  110  and a stator coil  120 . 
     The stator core  110  may be defined in a cylindrical shape by stacking a plurality of thinly formed electrical steel sheets in a circular shape and combining them in an axial direction (thickness direction). 
     The stator core  110  includes a base  111 , a rotor accommodating hole, a plurality of teeth  112 , and a plurality of slots  113 . 
     The base  111  defines an exterior of the stator core  110 . The rotor accommodating hole may be disposed inside the base  111 . 
     The plurality of teeth  112  are disposed to protrude in a radial direction from an inside of the base  111  toward the center of the rotor accommodating hole. 
     The plurality of slots  113  are disposed between the plurality of teeth  112 , and disposed to pass therethrough along an axial direction of the base  111 . The plurality of teeth  112  are alternately arranged along a circumferential direction. 
     The plurality of slots  113  may be respectively disposed to extend in a radial direction from an inside of the base  111  toward the rotor accommodating hole. 
     Each of the plurality of slots  113  is configured to accommodate a conductor  124  having a rectangular cross-sectional shape. 
     Each of the plurality of slots  113  may be defined in a rectangular shape. The plurality of conductors  124  may be disposed to be stacked in a radial direction in a single slot  113 . 
     A width of the slot  113  may be the same as or similar to a width of a single conductor  124 , and a radial depth of the slot  113  may be equal to or similar to a sum of the thicknesses of the plurality of conductors  124 . 
     Accordingly, the plurality of conductors  124  may be disposed to be stacked in a column in the single slot  113 . 
     A pole shoe may be disposed to protrude in a circumferential direction at an inner end of the tooth  112 . The pole shoe may prevent the conductor  124  from being released to an inside of the rotor accommodating hole. 
     The plurality of slots  113  may be respectively disposed to extend in a radially outward direction from an inside of the stator core  110 , and configured to have a first layer to an N-th layer. N is a natural number greater than or equal to 2. In the present embodiment, the plurality of layers are configured with first to eighth layers. 
     A single conductor  124  may be accommodated per layer of a particular slot  113 . 
     The plurality of slots  113  may be disposed to be spaced apart from one another in a circumferential direction of the stator core  110 , and may be configured with a first slot  113  to an M-th slot  113 . In the present embodiment, it is shown that the plurality of slots  113  are configured with 1st to 48th slots  113 . 
     The rotor accommodating hole is disposed to pass through the rotor  10  along an axial direction to accommodate the rotor  10  at an inner center of the stator  100 , and the rotor  10  is disposed to rotate about a rotation shaft with a predetermined air gap with respect to the stator core  110 . 
     The rotor  10  may include a rotor core  11  and a plurality of permanent magnets  12 . A plurality of permanent magnet accommodating holes  13  may be disposed in the rotor core  11 . The plurality of permanent magnets  12  are accommodated in the plurality of permanent magnet accommodating holes  13 . 
     The plurality of permanent magnets  12  may be defined in a flat plate shape. The plurality of permanent magnets  12  may be symmetrically disposed on both left and right sides with respect to a radial center line passing in a radial direction through the center of the rotor core  11 . 
     The plurality of permanent magnets  12  may be disposed to be inclined at different angles with respect to the radial center line. The plurality of permanent magnets  12  may be disposed to be spaced apart from one another in a radial direction. 
     The plurality of permanent magnets  12  may have a plurality of polarities in a circumferential direction. For example, the plurality of polarities may include N-poles and S-poles, and the N-poles and the S-poles may be alternately arranged in a circumferential direction. 
     The plurality of permanent magnets  12  may be configured to have a single polarity. 
     In the present embodiment, the rotor  10  may be configured to have 8 poles. 
     The stator coil  120  may be wound around the stator core  110  by electrically connecting the plurality of conductors  124  to one another. The plurality of conductors  124  may be respectively wrapped with an insulating paper or an insulating coating agent to be insulated from one another. 
     The stator coil  120  may be configured by connecting a plurality of hairpin-type conductors  124 . 
     The hairpin-type conductors  124  may have a rectangular cross-sectional shape and may be defined to have a larger length compared to the width and thickness of the cross-section. 
     Both sides of the hairpin-type conductor  124  are configured to be inserted into different slots  113 . 
     The hairpin-type conductor  124  may be formed by bending an elongated bar (or rod) having a rectangular cross-sectional shape into an approximate “U” shape. 
     The hairpin-type conductor  124  may include an insertion portion  1241 , a crossover portion  1242 , a bending portion  1243 , and a conductive portion  1244 . 
     The insertion portion  1241  of the conductor  124  is configured to extend in a straight line along the slot  113  so as to be inserted into the slot  113 . The conductor  124  may include a plurality of insertion portions  1241 , such as two insertions portions  1241 . 
     The two insertion portions  1241  may be accommodated in two different slots  113  at a preset slot pitch interval. 
     The slot pitch refers to an interval (distance) between the plurality of slots  113 . For example, 1-slot pitch refers to an interval between two slots  113  that is 1. More specifically, 1-slot pitch denotes an interval between two slots  113  that is equal to a width of a single tooth  112 . 
     Furthermore, m-slot pitch, which is a distance between a first slot  113  and a (m+1)-th slot  113 , denotes that m teeth  112  and (m−1) slots  113  are alternately arranged in a repeated manner along a circumferential direction. 
     A length of the insertion portion  1241  is the same as or similar to a stacked length or an axial length of the stator core  110 . 
     The crossover portion  1242  is configured to connect together one end of each of the plurality of insertion portions  1241 . 
     A length of the crossover portion  1242  is configured to correspond to an interval between the plurality of insertion portions  1241  respectively inserted into different slots  113 , that is, a slot pitch of the two insertion portions  1241 . 
     One end portion of the crossover portion  1242  is connected to one end of one insertion portion  1241  of the two insertion portions  1241 , and the other end portion of the crossover portion  1242  is connected to one end of the other insertion portion  1241  of the two insertion portions  1241 . 
     Both end portions of the crossover portion  1242  may be disposed adjacent to one end portion of the slot  113 , and a central portion of the crossover portion  1242  may be disposed in an axial direction spaced apart from the one end portion of the slot  113 . 
     Both sides of the crossover portion  1242  may be disposed to be inclined toward one end portion of the slot  113  from the central portion of the crossover portion  1242 . Both sides of the crossover portion  1242  may be disposed symmetrically left and right with respect to an axial center line passing the central portion of the crossover portion  1242  in an axial direction. 
     The bending portion  1243  may extend from the other end of the insertion portion  1241  and may be primarily bent to be inclined at a predetermined angle. 
     The bending portion  1243  may be configured in plurality, such as two, to extend from the two insertion portions  1241  of a single conductor  124 , respectively. 
     The plurality of bending portions  1243  may respectively extend to have the same length as one another. 
     The plurality of bending portions  1243  may be respectively bent to be inclined in opposite directions to each other. 
     The bending portion  1243  is configured to connect two different conductors  124  to each other. The bending portion  1243  may extend to a half distance (½) of an interval between the two different conductors  124 . 
     The conductive portion  1244  is secondarily bent to extend in a stacking direction or an axial direction of the stator core  110  from the bending portion  1243 . The conductive portion  1244 , which is a portion from which the insulating coating of the conductor  124  is removed, is configured to electrically connect the plurality of conductors  124 . 
     The conductive portions  1244  are configured in plurality, such as two, to extend from the two bending portions  1243  of the single conductor  124 , respectively. 
     One of the plurality of conductive portions  1244  of a one conductor  124  may be connected to be in contact with a conductive portion  1244  of another conductor  124 , and the other of the plurality of conductive portions  1244  of the one conductor  124  may be connected to be in contact with a conductive portion  1244  of yet another conductor  124 , thereby allowing the three conductors  124  to be conductively connected. 
     For example, the two conductors  124  may be spaced apart from each other at a predetermined interval in a circumferential direction of the stator core  110 , and the conductive portion  1244  of one conductor  124  and the conductive portion  1244  of the other conductor  124  for the two conductors  124  may be disposed and welded to overlap each other in a radial direction of the stator core  110  so as to be electrically connected to each other. 
     The plurality of conductors  124  may be divided into a long slot pitch conductor  124   a  having a long slot pitch interval (e.g., a 7-slot pitch) and a short slot pitch conductor  124   b  having a short slot pitch interval (e.g., a 5-slot pitch). 
     The stator coil  120  may include a plurality of phase coils respectively connected to the phases of the power source. 
     The plurality of phase coils may respectively have a first phase coil, a second phase coil, and a third phase coil. The first-phase coil may be a U-phase coil  121 , the second-phase coil may be a V-phase coil  122 , and the third-phase coil may be a W-phase coil  123 . 
     However, the U-phase coil  121 , the V-phase coil  122 , and the W-phase coil  123  are respectively wired with the same winding pattern, and therefore, only the U-phase coil  121  will be described as an example. 
     The stator coil  120  may be configured to have a plurality of parallel circuits in two slots  113  or more slots  113  for each pole and each phase. In the present embodiment, the stator coil  120  is configured with a plurality of parallel circuits in two slots  113  for each pole and each phase. 
     In the present embodiment, the rotary electric apparatus is a 3-phase, 8-pole, 48-slot, 8-layer model. 
     Since the rotary electric apparatus has eight poles, the number of slots  113  for each pole (a single pole) is six (48 slots/8 poles=6 slots/one pole). 
     Since the rotary electric apparatus has three phases, the number of slots  113  for each pole and each phase (one phase) is two (6 slots/3 phases=2 slots/one phase). 
     Two or more parallel circuits may be configured in two slots  113  for each pole and each phase. 
     The plurality of parallel circuits may be configured as an even number. 
     Two parallel circuits may be configured as a pair. 
     In the present embodiment, the stator coil  120  may be configured with four parallel circuits for each phase. 
     For example, each of the U-phase coil  121 , V-phase coil  122 , and W-phase coil  123  may be configured with first to fourth parallel circuits a1, a2, a3, a4. 
     A plurality of conductors  124  constituting each parallel circuit may be connected to one another in series. 
     A plurality of parallel circuits may be wound in pairs by two. 
     The first parallel circuit a1 and the second parallel circuit a2 may be wound to cross each other while constituting a pair. 
     The third parallel circuit a3 and the fourth parallel circuit a4 may be wound to cross each other while constituting a pair. 
     A pair of first and second parallel circuits a1, a2 and the other pair of third and fourth parallel circuits a3, a4 may be wound to cross each other. 
     Here, being wound to cross each other may be understood to denote that the plurality of conductors  124  constituting each parallel circuit are connected to each other while changing the slots  113  and layers to cross each other. 
     The plurality of conductors  124  constituting each parallel circuit may include a lead wire  125 , a neutral wire  126 , a standard wire, and a jumper wire  127 . 
     The lead wire  125  is a conductor  124  into which a current is drawn. The neutral wire  126  is the conductor  124  from which a current is drawn. The standard wire is a conductor  124  provided between the lead wire  125  and the neutral wire  126  to connect them. 
     The jumper wire  127  is a conductor  124  connecting the plurality of conductors  124  located in different layers. 
     Hereinafter, a wiring structure of the stator coil  120  provided with the first to fourth parallel circuits a1, a2, a3, a4 for each phase according to the present disclosure will be described. 
       FIG.  7    is a conceptual view showing a wiring structure of a plurality of parallel circuits for each layer according to the present disclosure. 
       FIG.  8    is a conceptual view showing a wiring diagram of first and second parallel circuits a1, a2 for a U-phase according to the present disclosure. 
     Each of the first parallel circuit a1 and the second parallel circuit a2 may include a first conductor  124  to a K-th conductor  124 . K is a natural number greater than or equal to 2. 
     A current is drawn into the first conductor  124  based on a direction in which the current flows, and a current is drawn from the K-th conductor. The current moves in order from the first conductor  124  to the K-th conductor  124 . 
     The first parallel circuit a1 and the second parallel circuit a2 may be respectively wound in a wave winding shape while constituting a pair. 
     Being wound in a wave winding shape denotes that winding is carried out in one direction (circumferential, clockwise, or counterclockwise) in a wave shape. 
     The first parallel circuit a1 and the second parallel circuit a2 may be disposed at a 1-slot pitch interval from each other. 
     In each of the first parallel circuit a1 and the second parallel circuit a2, a current may be drawn into the eighth layer, which is an outermost layer, and may be drawn from the first layer, which is an innermost layer. 
     The first conductor  124  to the K-th conductor  124  constituting the first parallel circuit a1 may be spaced apart from one another at a preset slot pitch interval in a circumferential direction and may be connected in series. The preset slot pitch may be a 6-slot pitch. 
     The preset slot pitch may be a total number of slots/a number of poles=48 slots/8 poles=6 slots/pole. The preset slot pitch may also be referred to as a regular pitch. 
     For example, the first conductor  124  and the second conductor  124  may be spaced apart from each other at a 6-slot pitch interval. 
     The first conductors  124  to K-th conductor  124  constituting the first parallel circuit a1 may be respectively connected in series by alternating the first insertion portion  1241  and the second insertion portion  1241  on both sides with different slot pitches in circumferential direction. 
     The different slot pitches may be a first slot pitch and a second slot pitch. The first slot pitch may be a long pitch that is 1-slot pitch larger than a regular pitch of 6-slot pitch. The first slot pitch may be a 7-slot pitch. 
     The second slot pitch may be a short pitch that is 1-slot pitch smaller than the regular pitch of 6-slot pitch. The second slot pitch may be a 5-slot pitch. 
     For example, the first parallel circuit a1 may have the following wiring structure. 
     The first conductor  124  may be connected to the lead wire  125  to allow a current to be drawn into the first conductor  124 . 
     The first insertion portion  1241  of the first conductor  124  is inserted into the eighth layer of the first slot  113 , and the second insertion portion  1241  of the first conductor  124  is inserted into the seventh layer of the 44th slot  113  in a first circumferential direction. The first insertion portion  1241  and the second insertion portion  1241  of the first conductor  124   b  are spaced apart from each other at a 5-slot pitch interval, which is a short pitch. The first circumferential direction is a direction in which a slot  113  number decreases. 
     The slot number is assigned to each slot  113  for convenience of description. 
     The first insertion portion  1241  and the second insertion portion  1241  of the first conductor  124   b  are accommodated in the eighth layer and the seventh layer, respectively, at a 5-slot pitch (short pitch) interval. The crossover portion  1242  of the first conductor  124  may extend by a distance of 5-slot pitch. 
     The second conductor  124   a  is connected in series with the first conductor  124   b  at a 6-slot pitch (regular pitch) interval. The bending portion  1243  of the first conductor  124   b  and the bending portion  1243  of the second conductor  124   a  extend in opposite directions toward each other by a distance of 3-slot pitch, respectively, and the conductive portion  1244  of the first conductor  124   b  and the conductive portion  1244  of the second conductor  124   a  may be connected to each other by welding. 
     The first insertion portion  1241  of the second conductor  124   a  is inserted into the eighth layer of the 38th slot  113 , and the second insertion portion  1241  of the second conductor  124   a  is inserted into the seventh layer of the 31st slot  113 . The first insertion portion  1241  and the second insertion portion  1241  of the second conductor  124   a  are spaced apart from each other at a 7-slot pitch interval, which is a long pitch. 
     The first insertion portion  1241  and the second insertion portion  1241  of the second conductor  124   a  are accommodated in the eighth layer and the seventh layer, respectively, at a 7-slot pitch (long pitch) interval. The crossover portion  1242  of the second conductor  124   a  may extend by a distance of 7-slot pitch. 
     The third conductor  124   b  is connected in series with the second conductor  124   a  at a 6-slot pitch (regular pitch) interval. The bending portion  1243  of the second conductor  124   a  and the bending portion  1243  of the third conductor  124   b  extend in opposite directions toward each other by a distance of 3-slot pitch, respectively, and the conductive portion  1244  of the second conductor  124   a  and the conductive portion  1244  of the third conductor  124   b  may be connected to each other by welding. 
     The first insertion portion  1241  of the third conductor  124   b  is inserted into the eighth layer of the 25th slot  113 , and the second insertion portion  1241  of the third conductor  124   b  is inserted into the seventh layer of the 20th slot  113 . The first insertion portion  1241  and the second insertion portion  1241  of the third conductor  124   b  are spaced apart from each other at a 5-slot pitch interval, which is a short pitch. 
     The first insertion portion  1241  and the second insertion portion  1241  of the third conductor  124   b  are accommodated in the eighth layer and the seventh layer, respectively, at a 5-slot pitch (short pitch) interval. The crossover portion  1242  of the third conductor  124   b  may extend by a distance of 5-slot pitch. 
     The fourth conductor  124   a  is connected in series with the third conductor  124   b  at a 6-slot pitch (regular pitch) interval. The bending portion  1243  of the third conductor  124   b  and the bending portion  1243  of the fourth conductor  124   a  extend in opposite directions toward each other by a distance of 3-slot pitch, respectively, and the conductive portion  1244  of the third conductor  124   b  and the conductive portion  1244  of the fourth conductor  124   a  may be connected to each other by welding. 
     The first insertion portion  1241  of the fourth conductor  124   a  is inserted into the eighth layer of the  14 th slot  113 , and the second insertion portion  1241  of the fourth conductor  124   a  is inserted into the seventh layer of the seventh slot  113 . The first insertion portion  1241  and the second insertion portion  1241  of the fourth conductor  124   a  are spaced apart from each other at a 7-slot pitch interval, which is a long pitch. 
     The first insertion portion  1241  and the second insertion portion  1241  of the fourth conductor  124   a  are accommodated in the eighth layer and the seventh layer, respectively, at a 7-slot pitch (long pitch) interval. The crossover portion  1242  of the fourth conductor  124   a  may extend by a distance of 7-slot pitch. 
     The fifth conductor  124   b  is connected in series with the fourth conductor  124   a  at a 6-slot pitch (regular pitch) interval. The bending portion  1243  of the fourth conductor  124   a  and the bending portion  1243  of the fifth conductor  124   b  extend in opposite directions toward each other by a distance of 5-slot pitch, respectively, and the conductive portion  1244  of the fourth conductor  124   a  and the conductive portion  1244  of the fifth conductor  124   b  may be connected to each other by welding. 
     The first insertion portion  1241  of the fifth conductor  124   b  is inserted into the sixth layer of the first slot  113 , and the second insertion portion  1241  of the fifth conductor  124   b  is inserted into the fifth layer of the 44th slot  113 . The first insertion portion  1241  and the second insertion portion  1241  of the fifth conductor  124   b  are spaced apart from each other at a 5-slot pitch interval, which is a short pitch. 
     The first insertion portion  1241  and the second insertion portion  1241  of the fifth conductor  124   b  are accommodated in the sixth layer and the fifth layer, respectively, at a 5-slot pitch (short pitch) interval. The crossover portion  1242  of the fifth conductor  124   b  may extend by a distance of 5-slot pitch. 
     The sixth conductor  124   a  to the eighth conductor  124   a  are respectively different from the second conductor  124   a  to the fourth conductor  124   a  in that the first and second insertion portions  1241  are inserted into the sixth and fifth layers, respectively, rather than the eighth and seventh layers. 
     However, the sixth conductor  124   a  to the eighth conductor  124   a  are the same as the second conductor  124   a  to the fourth conductor  124   a  in that the first and second insertion portions  1241  are disposed to be spaced apart by alternating long pitch and short pitch intervals, and are connected in series with each other, and thus a detailed description thereof will be omitted. 
     The ninth conductor  124   b  to the 12th conductor  124   a  are respectively different from the first conductor  124   b  to the fourth conductor  124   a  in that the first and second insertion portions  1241  are inserted into the fourth and third layers, respectively, rather than the eighth and seventh layers. 
     However, the ninth conductor  124   b  to the 12th conductor  124   a  are the same as the first conductor  124   b  to the fourth conductor  124   a  in that the first and second insertion portions  1241  are disposed to be spaced apart by alternating short pitch and long pitch intervals, and are connected in series with each other, and thus a detailed description thereof will be omitted. 
     The 13th conductor  124   b  to the 16th conductor  124   a  are different from the first conductor  124   b  to the fourth conductor  124   a  in that the first and second insertion portions  1241  are inserted into the second and first layers, respectively, rather than the eighth and seventh layers. 
     However, the 13th conductor  124   b  to the 16th conductor  124   a  are the same as the first conductor  124   b  to the fourth conductor  124   a  in that the first and second insertion portions  1241  are disposed to be spaced apart by alternating short pitch and long pitch intervals, and are connected in series with each other, and thus a detailed description thereof will be omitted. 
     The 16th conductor  124   a  may be connected to the neutral wire  126  to allow a current to be drawn from the 16th conductor 124 a.    
     The fourth conductor  124   a  and the fifth conductor  124   b,  the eighth conductor  124   a  and the ninth conductor  124   b,  and the 12th conductor  124   a  and the 13th conductor  124   b  are respectively connected to each other by the jumper wire  127 . 
     A group of the first conductor  124   b  to the fourth conductor  124   a,  a group of the fifth conductor  124   b  to the eighth conductor  124   a,  a group of the ninth conductor  124   b  to the 12th conductor  124   a,  and a group of the 13th conductor  124   b  to the 16th conductors  124   a  are respectively wired in series in the same pattern for each layer, that is, in the seventh-eighth layers, the fifth-sixth layers, the third-fourth layers, and the first-second layers, respectively. 
     The second parallel circuit a2 is different from the first parallel circuit a1 in that it is disposed to be spaced apart from the first parallel circuit a1 at a 1-slot pitch interval in a circumferential direction in the same layer. 
     However, the second parallel circuit a2 is the same as the first parallel circuit a1 in that the first conductor  124  to L-th conductor  124  constituting the second parallel circuit a2 are respectively connected in series by alternating the first insertion portion  1241  and the second insertion portion  1241  on both sides with different slot pitches in a circumferential direction, a redundant description of other configurations will be omitted. 
     In the case of a 3-phase 8-pole 48-slot model, a total of 16 standard-type conductors  124  may constitute the first parallel circuit a1, and a total of 16 standard-type conductors  124  may constitute the second parallel circuit a2. The number of conductors  124  of the first and second parallel circuits a1, a2 is 32 in total. 
     The standard-type conductors  124  constituting the first parallel circuit a1 and the second parallel circuit a2, respectively, may be connected in series by four in the same layer, that is, one of the eighth-seventh, the sixth-fifth, the fourth-third, and the second-first layers, and may be connected in series in a first circumferential direction while changing by two layers from an outermost layer to an innermost layer for each rotation. 
       FIG.  9    is a conceptual view showing a wiring diagram of third and fourth parallel circuits a3, a4 for a U-phase according to the present disclosure. 
     In the present embodiment, the third parallel circuit a3 and the fourth parallel circuit a4, which constitute a pair, are different from the circuit a1 and the second parallel circuit a2 in that a direction of current flow is opposite to that of the first and second parallel circuits a1 and a2. 
     The third parallel circuit a3 and the fourth parallel circuit a4 are configured such that a current flows in a second circumferential direction (a direction in which the slot number increases, counterclockwise) and from an innermost side to an outermost side in a radial direction. 
     In the case of the third parallel circuit a3, the first insertion portion  1241  and the second insertion portion  1241  of the first conductor  124   a  are respectively inserted into the first layer of the first slot  113  and the second layer of the eighth slot  113 . 
     A current flows in a second circumferential direction (from first slot  113  to eighth slot  113 ) and radial outward direction (from first layer to second layer) along the first conductor  124   a.    
     The first conductor  124   a  to the fourth conductor  124   b  are respectively spaced apart from one another at a regular pitch in a second circumferential direction in the same layers, that is, the first-second layers, and are connected in series. 
     The first and second insertion portions  1241  of each of the first conductor  124   a  to the fourth conductor  124   b  are spaced apart by alternating a first slot pitch (long pitch) and a second slot pitch (short pitch), which are different from each other, toward a second circumferential direction in the first-second layers. 
     The fifth conductor  124   a  to the eighth conductor  124   b  are respectively spaced apart from one another at a regular pitch in a second circumferential direction in the third-fourth layers, and are connected in series. 
     The first and second insertion portions  1241  of each of the fifth conductor  124   a  to the eighth conductor  124   b  are spaced apart by alternating a first slot pitch (long pitch) and a second slot pitch (short pitch), which are different from each other, toward a second circumferential direction in the third-fourth layers. 
     The ninth conductor  124   a  to the 12th conductor  124   b  are respectively spaced apart from one another at a regular pitch in a second circumferential direction in the fifth-sixth layers, and are connected in series. 
     The first and second insertion portions  1241  of each of the ninth conductor  124   a  to the 12th conductor  124   b  are spaced apart by alternating a first slot pitch (long pitch) and a second slot pitch (short pitch), which are different from each other, toward a second circumferential direction in the fifth-sixth layers. 
     The 13th conductor  124   a  to the 16th conductor  124   b  are respectively spaced apart from one another at a regular pitch in a second circumferential direction in the seventh-eighth layers, and are connected in series. 
     The first and second insertion portions  1241  of each of the 13th conductor  124   a  to the 16th conductor  124   b  are spaced apart by alternating a first slot pitch (long pitch) and a second slot pitch (short pitch), which are different from each other, toward a second circumferential direction in the seventh-eighth layers. 
     The fourth parallel circuit a4 is different from the third parallel circuit a3 in that it is disposed to be spaced apart from the third parallel circuit a3 at a 1-slot pitch interval. 
     However, the third parallel circuit a3 and the fourth parallel circuit a4 are wired in the same pattern while constituting a pair. 
     In the case of the fourth parallel circuit a4, the first insertion portion  1241  of the first conductor  124  is inserted into the first layer of the second slot  113 , and a current is drawn into the first conductor  124 . 
     The third parallel circuit a3 draws a current from the eighth layer of the 43rd slot  113 , and the fourth parallel circuit a4 draws a current from the eighth layer of the 44th slot  113 . 
     The neutral wire  126  drawn from each of the first and second parallel circuits a1 and a2 may be connected in parallel with the neutral wire  126  drawn from the third and fourth parallel circuits a3, a4. 
     Hereinafter, the operation and effect of a wiring structure of a plurality of parallel circuits in each phase coil according to the present disclosure will be described. 
     The first parallel circuit a1 and the second parallel circuit a2 are connected in parallel while constituting a pair. 
     The first parallel circuit a1 and the second parallel circuit a2 are spaced apart from each other at a 1-slot pitch interval. 
     The first conductor  124  to K-th conductor  124  constituting the first parallel circuit a1 are spaced apart from one another at a regular slot pitch (6-slot pitch) interval and are connected in series. 
     The first, third, . . . , and (2k−1)-th conductors  124   b,  which are odd-numbered conductors  124   b,  and the second, fourth, . . . , and 2k-th conductors  124   a,  which are even-numbered conductors  124   a,  have different slot pitch intervals. 
     Both sides of the odd-numbered conductor  124   b  are accommodated in different layers with a short slot pitch (5-slot pitch) interval in a first circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the odd-numbered conductor  124   b  are accommodated in the N-th layer of the M-th slot  113  and the (N−1)-th layer of the (M−5)-th slot  113 , respectively, and are spaced apart at a 5-slot pitch interval. 
     Both sides of the even-numbered conductor  124   a  are accommodated in different layers with a long slot pitch (7-slot pitch) interval in a first circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the even-numbered conductor  124   a  are accommodated in the N-th layer of the (M−11)-th slot  113  and the (N−1)-th layer of the (M−18)-th slot  113 , respectively, and are spaced apart at a 7-slot pitch interval. 
     The second insertion portion  1241  of the odd-numbered conductor  124   b  accommodated in the (N−1)-th layer of the (M−5)-th slot  113  is connected to the first insertion portion  1241  of the even-numbered conductor  124   a  accommodated in the N-th layer of the (M−11)-th slot  113 . 
     The second bending portion  1243  of the odd-numbered conductor  124   b  is primarily bent to extend in a first circumferential direction and a radially outward direction from the second insertion portion  1241  of the odd-numbered conductor  124   b  toward the first insertion portion  1241  of the even-numbered conductor  124   a.    
     The first bending portion  1243  of the even-numbered conductor  124   a  is primarily bent to extend in a second circumferential direction and a radially inward direction from the first insertion portion  1241  of the even-numbered conductor  124   a  toward the second insertion portion  1241  of the odd-numbered conductor  124   b.    
     The second conductive portion  1244  that is secondarily bent at the second bending portion  1243  of the odd-numbered conductor  124   b  is electrically connected to the first conductive portion  1243  that is secondarily bent at the first bending portion  1243  of the even-numbered conductor  124   a.    
     The first conductor  124   a  to L-th conductor  124  constituting the second parallel circuit a2 are spaced apart from one another at a regular slot pitch (6-slot pitch) interval and are connected in series. 
     The first, third, . . . , and (2I−1)-th conductors  124   a,  which are odd-numbered conductors  124   a,  and the second, fourth, . . . , and 2I-th conductors  124   b,  which are even-numbered conductors  124   b,  have different slot pitch intervals. 
     Both sides of the odd-numbered conductor  124   a  are accommodated in different layers with a long slot pitch (7-slot pitch) interval in a first circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the odd-numbered conductor  124   a  are accommodated in the N-th layer of the (M+1)-th slot  113  and the (N−1)-th layer of the (M−6)-th slot  113 , respectively, and are spaced apart at a 7-slot pitch interval. 
     Both sides of the even-numbered conductor  124   b  are accommodated in different layers with a short slot pitch (5-slot pitch) interval in a first circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the even-numbered conductor  124   b  are accommodated in the N-th layer of the (M−12)-th slot  113  and the (N−1)-th layer of the (M−17)-th slot  113 , respectively, and are spaced apart at a 5-slot pitch interval. 
     The second insertion portion  1241  of the odd-numbered conductor  124   a  accommodated in the (N−1)-th layer of the (M−6)-th slot  113  is connected to the first insertion portion  1241  of the even-numbered conductor  124   b  accommodated in the N-th layer of the (M−12)-th slot  113 . 
     The second bending portion  1243  of the odd-numbered conductor  124   a  is primarily bent to extend in a first circumferential direction and a radially outward direction from the second insertion portion  1241  of the odd-numbered conductor  124   a  toward the first insertion portion  1241  of the even-numbered conductor  124   b.    
     The first bending portion  1243  of the even-numbered conductor  124   b  is primarily bent to extend in a second circumferential direction and a radially inward direction from the first insertion portion  1241  of the even-numbered conductor  124   b  toward the second insertion portion  1241  of the odd-numbered conductor  124   a.    
     The second conductive portion  1244  that is secondarily bent at the second bending portion  1243  of the odd-numbered conductor  124   a  is electrically connected to the first conductive portion  1243  that is secondarily bent at the first bending portion  1243  of the even-numbered conductor  124   b.    
     Here, an extension direction of the bending portion  1243  connecting the second insertion portion  1241  of the odd-numbered conductor  124  and the first insertion portion  1241  of the even-numbered conductor  124  of the first parallel circuit a1 and the conductive portion  1244  intersects with an extension direction of the bending portion  1243  connecting the second insertion portion  1241  of the odd-numbered conductor  124  and first insertion portion  1241  of the even-numbered conductor  124  of the second parallel circuit a2 and the conductive portion  1244 . 
     The third parallel circuit a3 and the fourth parallel circuit a4 are connected in parallel while constituting a pair. 
     The first parallel circuit a3 and the second parallel circuit a4 are spaced apart from each other at a 1-slot pitch interval. 
     The first conductor  124  to the P-th conductor  124  constituting the third parallel circuit a3 are spaced apart from one another at a regular slot pitch (6-slot pitch) interval and are connected in series. 
     The first, third, . . . , and (2p−1)-th conductors  124   a,  which are odd-numbered conductors  124   a,  and the second, fourth, . . . , and 2p-th conductors  124   b,  which are even-numbered conductors  124   b,  have different slot pitch intervals. 
     Both sides of the odd-numbered conductor  124   a  are accommodated in different layers with a long slot pitch (7-slot pitch) interval in a second circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the odd-numbered conductor  124   a  are accommodated in the N-th layer of the M-th slot  113  and the (N+1)-th layer of the (M+7)-th slot  113 , respectively, and are spaced apart at a 7-slot pitch interval. Each of M and N is a natural number greater than or equal to 1. 
     Both sides of the even-numbered conductor  124   b  are accommodated in different layers with a short slot pitch (5-slot pitch) interval in a second circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the even-numbered conductor  124   b  are accommodated in the N-th layer of the (M+13)-th slot  113  and the (N+1)-th layer of the (M+18)-th slot  113 , respectively, and are spaced apart at a 5-slot pitch interval. 
     The second insertion portion  1241  of the odd-numbered conductor  124   a  accommodated in the (N+1)-th layer of the (M+7)-th slot  113  is connected to the first insertion portion  1241  of the even-numbered conductor  124   b  accommodated in the N-th layer of the (M+13)-th slot  113 . 
     The second bending portion  1243  of the odd-numbered conductor  124   a  is primarily bent to extend in a second circumferential direction and a radially inward direction from the second insertion portion  1241  of the odd-numbered conductor  124   a  toward the first insertion portion  1241  of the even-numbered conductor  124   b.    
     The first bending portion  1243  of the even-numbered conductor  124   b  is primarily bent to extend in a second circumferential direction and a radially outward direction from the first insertion portion  1241  of the even-numbered conductor  124   b  toward the second insertion portion  1241  of the odd-numbered conductor  124   a.    
     The second conductive portion  1244  that is secondarily bent at the second bending portion  1243  of the odd-numbered conductor  124   a  is electrically connected to the first conductive portion  1243  that is secondarily bent at the first bending portion  1243  of the even-numbered conductor  124 . 
     The first conductor  124  to Q-th conductor  124  constituting the fourth parallel circuit a4 are spaced apart from one another at a regular slot pitch (6-slot pitch) interval and are connected in series. 
     The first, third, . . . , and (2q−1)-th conductors  124   b,  which are odd-numbered conductors  124   b,  and the second, fourth, . . . , and 2q-th conductors  124   a,  which are even-numbered conductors  124   a,  have different slot pitch intervals. 
     Both sides of the odd-numbered conductor  124   b  are accommodated in different layers with a short slot pitch (5-slot pitch) interval in a second circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the odd-numbered conductor  124   b  are accommodated in the N-th layer of the (M+1)-th slot  113  and the (N+1)-th layer of the (M+6)-th slot  113 , respectively, and are spaced apart at a 5-slot pitch interval. 
     Both sides of the even-numbered conductor  124   a  are accommodated in different layers with a long slot pitch (7-slot pitch) interval in a second circumferential direction. 
     The first insertion portion  1241  and the second insertion portion  1241  of the even-numbered conductor  124   a  are accommodated in the N-th layer of the (M+12)-th slot  113  and the (N+1)-th layer of the (M+19)-th slot  113 , respectively, and are spaced apart at a 7-slot pitch interval. 
     The second insertion portion  1241  of the odd-numbered conductor  124   b  accommodated in the (N+1)-th layer of the (M+6)-th slot  113  is connected to the first insertion portion  1241  of the even-numbered conductor  124   a  accommodated in the N-th layer of the (M+12)-th slot  113 . 
     The second bending portion  1243  of the odd-numbered conductor  124   b  is primarily bent to extend in a second circumferential direction and a radially inward direction from the second insertion portion  1241  of the odd-numbered conductor  124   b  toward the first insertion portion  1241  of the even-numbered conductor  124   a.    
     The first bending portion  1243  of the even-numbered conductor  124   a  is primarily bent to extend in a first circumferential direction and a radially outward direction from the first insertion portion  1241  of the even-numbered conductor  124   a  toward the second insertion portion  1241  of the odd-numbered conductor  124   b.    
     The second conductive portion  1244  that is secondarily bent at the second bending portion  1243  of the odd-numbered conductor  124   b  is electrically connected to the first conductive portion  1243  that is secondarily bent at the first bending portion  1243  of the even-numbered conductor  124   a.    
     Here, an extension direction of the bending portion  1243  connecting the second insertion portion  1241  of the odd-numbered conductor  124   a  and the first insertion portion  1241  of the even-numbered conductor  124   b  of the third parallel circuit a3 and a welding portion intersects with an extension direction of the bending portion  1243  connecting the second insertion portion  1241  of the odd-numbered conductor  124   b  and the first insertion portion of the even-numbered conductor  124   a  of the fourth parallel circuit a4 and a welding portion. 
     In addition, each of the first and second parallel circuits a1, a2 is wound from an outermost layer toward an innermost layer of the first slot  113  and the second slot  113  in a direction (first circumferential direction) in which the slot number decreases, and each of the third and fourth parallel circuits a3, a4 is wound from an innermost layer toward an outermost layer of the first slot  113  and the second slot  113  in a direction (second circumferential direction) in which the slot number increases. 
     According to this configuration, a plurality of conductors  124  constituting each of a plurality of parallel circuits may be configured with two types of hairpin-type conductors  124  having different slot pitches, that is, a long slot pitch and a short slot pitch, and the two types of hairpin-type conductors  124  may be alternately arranged along a circumferential direction in all layers, and wired in directions crossing each other, thereby allowing the plurality of conductors  124  constituting each parallel circuit to be evenly distributed in all slots  113  and layers to constitute a balanced parallel circuit. 
     Therefore, according to the present disclosure, in a balanced parallel circuit, an amount of interlinkage magnetic flux of each parallel circuit may be the same, and a current may flow in a balanced manner along a plurality of parallel circuits. 
     Furthermore, an impedance of each parallel circuit may be uniformly defined. 
     Moreover, a current may flow evenly to each parallel circuit, thereby solving a problem in that a heat generation phenomenon of a specific coil occurs due to the bias of the current. 
     In addition, a current may flow evenly in each parallel circuit, thereby facilitating control during a high-speed operation. 
     Additionally, a current may flow in a balanced manner in each parallel circuit to evenly generate a torque in each parallel circuit, thereby minimizing electromagnetic noise and vibration. 
     Moreover, two types of hairpin-type coils provided with a conductor  124   a  having a long slot pitch and a conductor  124   b  having a short slot pitch may be applicable to all layers to reduce the number of types of hairpins, thereby improving productivity and reducing manufacturing cost. 
     In addition, the two types of hairpin-type conductors  124   a,    124   b  having a long slot pitch and a short slot pitch may be identically used for each layer, thereby simplifying the structure of a coil. 
     In addition, a lead wire  125  (lead line) into which a current is drawn, a neutral wire  126  (neutral line) from which the current is drawn, and a jumper wire  127  connecting two conductors located in different layers may be compactly arranged in any one of four sections of the stator  100  being divided into four quarters of a circumference along a circumferential direction of the stator  100 . 
       FIG.  10    is a graph of a waveform showing an amount of interlinkage magnetic flux of an unbalanced parallel circuit in the related art. 
       FIG.  11    is a graph of a waveform showing an amount of interlinkage magnetic flux of a balanced parallel circuit in the present disclosure. 
     In  FIGS.  10  and  11   , the X-axis is an angle (degree), and the Y-axis is relative back-EMF (relative back electromotive force; %). 
     Referring to  FIG.  10    (the related art), amounts of interlinkage magnetic flux (a1=a3≠a2=a4) of an unbalanced parallel circuit are different from one another. 
     Referring to  FIG.  11    (the present disclosure), amounts of interlinkage magnetic flux (a1=a3=a2=a4) of a balanced parallel circuit are the same. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.