Stator and motor

Abstract

This stator comprises: an annular stator core in which a plurality of slots are formed side by side in the circumferential direction, and which has a plurality of teeth formed between the adjacent slots and protruding in the radial direction; and a plurality of windings wound around the plurality of teeth. Each of the plurality of windings is a multi-strand wire formed by bundling a plurality of strands, and has a plurality of coil sections provided in parallel to each other and wound around the teeth by concentrated winding. The plurality of coil sections each have a first layer section disposed along the outer periphery of the teeth from one end side to the other end side in the protruding direction of the teeth, and a second layer section disposed on the outer peripheral side of the first layer section.

Description

Stator and Motor

[0001] The present disclosure relates to a stator and a motor. The present disclosure claims priority based on Japanese Patent Application No. 2025-053032 filed in Japan on March 27, 2025, the content of which is incorporated herein by reference.

[0002] Patent Document 1 discloses a stator having a plurality of tooth portions protruding in the radial direction of an annular portion, wherein a plurality of coil winding portions defined side by side in the radial direction and having the same length in the radial direction are provided on each tooth portion, and a coil with the same number of turns is wound around each of the plurality of coil winding portions of each tooth portion. Patent Document 2 discloses a configuration in which in each tooth, a first region where a first winding is concentratedly wound and a second region where a second winding is concentratedly wound are different from each other, and the first winding and the second winding are concentratedly wound on each tooth such that the magnetic path lengths between the first winding and the second winding are equal.

[0003] Japanese Unexamined Patent Publication No. 2017-121158, Japanese Unexamined Patent Publication No. 2014-45540

[0004] In the configuration disclosed in Patent Document 1, coils wound on the radially outer portion and the radially inner portion of the tooth portion partially overlap each other in a direction intersecting the radial direction, which may cause winding collapse or the like. In this case, a large local gap is generated, and there is a concern that the space factor may decrease. In the configuration disclosed in Patent Document 2, the first winding and the second winding are concentratedly wound on each tooth via a protrusion protruding outward along the rotation direction of the motor at the central portion of each tooth in the extension direction. In the configuration disclosed in Patent Document 2, a decrease in space factor caused by the protrusion is a problem.

[0005] An object of an aspect of the present disclosure is to provide a stator and a motor that can suppress a decrease in space factor.

[0006] A stator according to one aspect of the present disclosure comprises an annular stator core having a plurality of slots arranged in the circumferential direction and a plurality of teeth formed between adjacent slots and protruding radially, and a plurality of windings wound around the plurality of teeth, each of which is a multi-strand wire made of a plurality of strands bundled together, and has a plurality of coil portions arranged in parallel with each other and wound around the teeth by concentrated winding, each of which has a first layer portion arranged along the outer circumference of the teeth from one end to the other in the protruding direction of the teeth, and a second layer portion arranged on the outer circumference side of the first layer portion.

[0007] According to aspects of this disclosure, it is possible to provide a stator and a motor that can suppress a decrease in the space factor.

[0008] This is a schematic cross-sectional view showing a motor according to the embodiment. This is a perspective view showing an example of a stator in the motor according to the embodiment when the number of slots is 36. This is a cross-sectional view from the axial direction of an example of a motor in the motor according to the embodiment when the number of rotor poles is 10 and the number of stator slots is 12. This is a cross-sectional view from the axial direction of an example of the laminated structure of the coil section in the stator according to the embodiment. This is a circuit diagram showing an example of a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the embodiment. This is a diagram showing an example of a winding connection diagram in a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the embodiment, divided into U-phase, V-phase, and W-phase. This is a circuit diagram showing an example of a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the embodiment. This is a circuit diagram showing an example of a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the second embodiment. This is a circuit diagram showing an improved example of a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the second embodiment. This figure shows an example of a winding connection diagram for an improved three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the second embodiment, divided into U-phase, V-phase, and W-phase. This is a cross-sectional view of an example of the coil stacking structure in the stator according to the third embodiment, viewed from the axial direction. This is a circuit diagram showing an example of a three-phase AC circuit in the case of three parallel, three-turn windings in the stator according to the third embodiment. This figure shows an example of a winding connection diagram for a three-phase AC circuit in the case of three parallel, three-turn windings in the stator according to the third embodiment, divided into U-phase, V-phase, and W-phase. This is a circuit diagram showing an example of a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the fourth embodiment. This figure shows an example of a winding connection diagram for a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the fourth embodiment, divided into U-phase, V-phase, and W-phase. This is a circuit diagram showing an example of a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the fifth embodiment. This is a circuit diagram showing an example of a three-phase AC circuit in the case of two parallel, two-turn windings in the stator according to the sixth embodiment. This figure shows an example of the relationship between the wire diameter and number of strands of wires constituting the multi-strand wire in each layer of the stator according to the sixth embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In this embodiment, a three-phase AC motor will be described as an example of a motor.

[0010] In the following explanation, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "centered," and "coaxial," mean not only strictly such arrangements or states, but also include arrangements or states that are relatively displaced by angles or distances that allow for tolerances or similar functions. In the drawings used in the following explanation, the scale of each component may be changed as appropriate to make each component recognizable.

[0011] <Motor> Figure 1 is a schematic cross-sectional view showing a motor 1 according to an embodiment. Figure 2 is a perspective view showing an example of a stator 3 in the motor 1 according to an embodiment, where the number of slots is 36. Figure 3 is a cross-sectional view from the axial direction of an example of a motor 1 in the motor 1 according to an embodiment, where the number of poles of the rotor 2 is 10 and the number of slots of the stator 3 is 12. Referring together to Figures 1 to 3, the motor 1 comprises a rotor 2 and a stator 3.

[0012] In the following explanation, the direction parallel to the axis O of the rotor 2 and stator 3 is called the axial direction. The radial direction of axis O (the direction perpendicular to axis O) is called the radial direction. The direction that circles axis O is called the circumferential direction. Furthermore, one side of the axial direction is called the upper side (upward direction), and the other side of the axial direction is called the lower side (downward direction). In the radial direction, the direction approaching axis O is called the radially inward direction, and the direction moving away from axis O is called the radially outward direction. One side of the circumferential direction is called the first circumferential direction RD1, and the other side of the circumferential direction is called the second circumferential direction RD2.

[0013] <Rotor> The rotor 2 comprises a rotor shaft 21, a rotor core 22, and a plurality of magnets 23.

[0014] The rotor shaft 21 is a rod-shaped member that extends axially with respect to the axis O. The rotor shaft 21 is formed in a circular shape with respect to the axis O when viewed from the axial direction. The rotor shaft 21 is rotatably mounted around the axis O.

[0015] The rotor core 22 may be composed of, for example, multiple steel plates stacked in the axial direction. The rotor core 22 is formed in a cylindrical shape centered on axis O. The rotor core 22 is fixed to the outer circumferential surface of the rotor shaft 21. The rotor core 22 may have a shorter axial length than, for example, the rotor shaft 21.

[0016] The magnet 23 is, for example, a permanent magnet. For example, if multiple magnets 23 each constitute one magnetic pole, the multiple magnets 23 may be arranged at equal intervals in the circumferential direction of the rotor 2 on the outer circumference of the rotor 2. Alternatively, for example, multiple magnets 23 may constitute one magnetic pole. Multiple magnets 23 constituting one magnetic pole may be arranged at equal intervals in the circumferential direction of the rotor 2 on the outer circumference of the rotor 2. The magnet 23 is, for example, embedded inside the rotor core 22. The magnet 23 may be, for example, attached to the surface of the rotor core 22.

[0017] <Stator> The stator 3 comprises a stator core 4, an insulator 5, and a plurality of windings 6.

[0018] The stator core 4 is constructed, for example, by laminating multiple electrical steel sheets in the axial direction. The stator core 4 may also be constructed, for example, by powder molding. The stator core 4 is formed in a cylindrical shape with axis O as the center. Inside the stator core 4, the rotor 2 is housed so as to be rotatable around axis O. The stator core 4 comprises a cylindrical yoke 41 and a plurality of teeth 42.

[0019] The stator core 4 has a plurality of slots 43 arranged in the circumferential direction. Multiple teeth 42 are formed between adjacent slots 43 and protrude radially.

[0020] In this embodiment, the multiple teeth 42 protrude radially inward from the inner circumferential surface of the yoke 41 and are arranged at intervals in the circumferential direction of the stator core 4. Slots 43 are formed between adjacent teeth 42 in the circumferential direction. As a result, the multiple teeth 42 and the multiple slots 43 are formed alternately in the circumferential direction of the stator core 4. Specifically, the multiple teeth 42 are formed to be the same shape and size as each other. The multiple teeth 42 are arranged at equal intervals in the circumferential direction. Therefore, the multiple slots 43 are arranged at equal intervals in the circumferential direction of the stator core 4. As a result, the multiple teeth 42 and slots 43 are formed alternately in the circumferential direction at equal intervals.

[0021] <Insulator> The insulator 5 is made of an insulating material, such as a synthetic resin material. The insulator 5 may be molded by, for example, injection molding. The insulator 5 has the function of electrically insulating the winding 6 from the stator core 4. The insulator 5 is attached to the stator core 4 so as to cover at least a part of the surface of the stator core 4. The insulator 5 covers at least the outer circumferential surface of each tooth 42 around which the coil portion 61 of the winding 6 is wound, and the inner circumferential surface of the yoke 41 on which the teeth 42 are installed.

[0022] The insulator 5 has a main body that covers the outer circumferential surfaces of the multiple teeth 42 and the inner circumferential surface of the yoke 41, and a winding holding portion 51. The winding holding portion 51 is located on the upper end side of the stator core 4. The winding holding portion 51 may also be located on the lower end side of the stator core 4, for example. The winding holding portion 51 may be located on either end side in the axial direction of the stator core 4. The winding holding portion 51 is formed in an annular shape with axis O as the center.

[0023] The winding holder 51 has multiple connecting grooves 52 formed therein for accommodating the connecting wires 62 of the windings 6. The multiple connecting grooves 52 are recessed from the outer circumference of the winding holder 51 and extend in the circumferential direction. The multiple connecting grooves 52 are arranged in the axial direction. The multiple connecting grooves 52 accommodate the connecting wires 62 of windings 6 with different phases.

[0024] In this embodiment, there are three crossover grooves 52. Each of the three crossover sections 62 accommodates a crossover section 62 for the windings 6 of the three phases (U phase, V phase, and W phase). Specifically, the three crossover grooves 52 are the U phase crossover groove 52U (first phase crossover groove, first crossover groove), the V phase crossover groove 52V (second phase crossover groove, second crossover groove), and the W phase crossover groove 52W (third phase crossover groove, third crossover groove), which are arranged in order from the stator core 4 side in the axial direction. In the illustrated example, the U phase crossover groove 52U, the V phase crossover groove 52V, and the W phase crossover groove 52W are arranged in order in the upward direction in the axial direction.

[0025] <Windings> Multiple windings 6 are wound around multiple teeth 42. Each of the multiple windings 6 is a multi-strand wire 60M made up of multiple strands 60W bundled together (see Figure 4). The multi-strand wire 60M may be made up of multiple strands 60W bundled together in an unaligned manner, for example. The multiple windings 6 are provided in parallel with each other. In this embodiment, each of the multiple strands 60W is made up of a round wire.

[0026] Referring together to Figures 1, 5, and 6, each of the multiple windings 6 is wound around multiple teeth 42 via an insulator 5. The three windings 6 are assigned to one of the three phases (U-phase, V-phase, and W-phase). The three windings 6 include a U-phase winding 6U (first phase winding), a V-phase winding 6V (second phase winding), and a W-phase winding 6W (third phase winding). In the three phase windings 6U, 6V, and 6W, the number of coil sections 61 is equal to each other.

[0027] Figure 5 shows an example of a three-phase AC circuit with two parallel, double-wound windings. As shown in Figure 5, the three-phase AC circuit employs a star connection in which the three phase windings 6U, 6V, and 6W are connected at neutral points N1 and N2. If the number of parallel connections is three or more, the same number of star connections as shown in Figure 5 should be prepared, and the input points U1, V1, and W1 of the same phase in the multiple star connections should be connected to the same terminal. The input points U1, V1, and W1 are the first ends in the longitudinal direction of the winding 6 and are terminals for inputting drive current to the winding 6.

[0028] In the example shown in Figure 6, an example of a winding diagram for a three-phase AC circuit with two parallel, double-wound windings is shown, divided into U-phase, V-phase, and W-phase. In Figure 6, the stator 3 is unfolded linearly so that its circumferential direction extends in the left-right direction, and the teeth 42 of the stator 3, the three connecting grooves 52 of the insulator 5, etc. are schematically shown. An example of a winding diagram for the winding 6 is also shown, divided into three parts: U-phase, V-phase, and W-phase. Furthermore, because it is two parallel, double-wound, the winding 6 for each phase is divided into two parts in the circumferential direction of the stator 3.

[0029] Each of the multiple windings 6 has multiple coil sections 61, at least one jumper section 62, and two lead-out sections 63. In the same winding 6, each of the multiple coil sections 61 is wound around the teeth 42 by concentrated winding. In Figure 6, the coil sections 61 are shown surrounding the teeth 42 from below, but in reality, they are wound around the teeth 42 by concentrated winding.

[0030] The jumper wires 62 connect adjacent coil sections 61 in multiple coil sections 61 (in the example shown in Figure 6, the coil sections 61 of the U-phase winding 6U (first-phase winding), the coil sections 61 of the V-phase winding 6V (second-phase winding), and the coil sections 6W (second-phase winding)). The number of jumper wires 62 is one less than the number of coil sections 61. The two lead wires 63 form the ends of the same winding 6. The two lead wires 63 extend from the coil section 61.

[0031] In the stator 3, the coil sections 61 of the U-phase winding 6U, the V-phase winding 6V, and the W-phase winding 6W are arranged in a repeating sequence in the circumferential direction. Therefore, the coil sections 61 of windings 6 of the same phase are wound around teeth 42, which are arranged every three teeth. The example in Figure 6 shows the case where there are 12 slots. In the example in Figure 6, in each parallel circuit of each phase, a single turn (first layer) is shown as a solid line winding, and a double turn (second layer) is shown as a dashed line winding.

[0032] In the example shown in Figure 6, in each parallel U-phase circuit, the two coil sections 61 (solid and dashed windings) of the U-phase winding 6U, which is wound around the first division (the first of two divisions), are wound around the first and fourth teeth 42 (42-1, 42-4). In each parallel U-phase circuit, the two coil sections 61 (solid and dashed windings) of the U-phase winding 6U, which is wound around the second division (the second of two divisions), are wound around the seventh and tenth teeth 42 (42-7, 42-10). In each parallel V-phase circuit, the two coil sections 61 (solid and dashed windings) of the V-phase winding 6V, which is wound around the first division, are wound around the second and fifth teeth 42 (42-2, 42-5). In each parallel V-phase circuit, the two coil sections 61 (solid and dashed windings) of the V-phase winding 6V, which is wound in the second division, are wound around the 8th and 11th teeth 42 (42-8, 42-11). In each parallel W-phase circuit, the two coil sections 61 (solid and dashed windings) of the W-phase winding 6W, which is wound in the first division, are wound around the 3rd and 6th teeth 42 (42-3, 42-6). In each parallel W-phase circuit, the two coil sections 61 (solid and dashed windings) of the W-phase winding 6W, which is wound in the second division, are wound around the 9th and 12th teeth 42 (42-9, 42-12). In the example in Figure 6, the U-phase coil section 61U, the V-phase coil section 61V, and the W-phase coil section 61W are arranged in a repeating order to the right (first rotation direction RD1). Therefore, the numbers on teeth 42, as mentioned above, are arranged sequentially from left to right.

[0033] Furthermore, the jumper wire portion 62 of the U-phase winding 6U is housed in the U-phase jumper groove 52U. Similarly, the jumper wire portion 62 of the V-phase winding 6V is housed in the V-phase jumper groove 52V. The jumper wire portion 62 of the W-phase winding 6W is housed in the W-phase jumper groove 52W.

[0034] In the stator 3 illustrated in Figure 6, in each parallel circuit of each phase, the second end of each winding 6 wound in the first division, which is located opposite the first end that forms the input points U1 (U1-(1) shown as a solid line, U1-(2) shown as a dashed line), V1 (V1-(1) shown as a solid line, V1-(2) shown as a dashed line), and W1 (W1-(1) shown as a solid line, W1-(2) shown as a dashed line), is the output point Un1 (Un1-(1) shown as a solid line, Un1-(2) shown as a dashed line), Vn1 (Vn1-(1) shown as a solid line, Vn1-(2) shown as a dashed line), and Wn1 (Wn1-(1) shown as a solid line, Wn1-(2) shown as a dashed line). In each parallel circuit of each phase, the second end of each winding 6 that is wound around the second division, opposite to the first end which forms the input points U2 (U2-(1) shown as a solid line, U2-(2) shown as a dashed line), V2 (V2-(1) shown as a solid line, V2-(2) shown as a dashed line), and W2 (W2-(1) shown as a solid line, W2-(2) shown as a dashed line), is the output point Un2 (Un2-(1) shown as a solid line, Un2-(2) shown as a dashed line), Vn2 (Vn2-(1) shown as a solid line, Vn2-(2) shown as a dashed line), and Wn2 (Wn2-(1) shown as a solid line, Wn2-(2) shown as a dashed line).

[0035] The three-phase output points Un1 (shown as a solid line, Un1-(1)), Vn1 (shown as a solid line, Vn1-(1)), Wn1 (shown as a solid line, Wn1-(1)), and output points Un2 (shown as a solid line, Un2-(1)), Vn2 (shown as a solid line, Vn2-(1)), and Wn2 (shown as a solid line, Wn2-(1)) constitute the neutral point N1 of the connection shown in Figure 5. The three-phase output points Un1 (shown as a dashed line, Un1-(2)), Vn1 (shown as a dashed line, Vn1-(2)), Wn1 (shown as a dashed line, Wn1-(2)), and output points Un2 (shown as a dashed line, Un2-(2)), Vn2 (shown as a dashed line, Vn2-(2)), and Wn2 (shown as a dashed line, Wn2-(2)) constitute the neutral point N2 of the connection shown in Figure 9.

[0036] In the example shown in Figure 6, the first layer (solid line) and the second layer (dashed line), wound around different teeth in the same phase, are connected to each other by a neutral wire (neutral point connection) so that they form independent parallel circuits. The neutral point connections of each of the three phases result in coils of the same layer, and when viewed between the wires, the first layers (solid lines) are paired together.

[0037] Specifically, the output point of the first layer of the first division of the U-phase (shown as a solid line, Un1-(1)), the output point of the first layer of the first division of the V-phase (shown as a solid line, Vn1-(1)), and the output point of the first layer of the first division of the W-phase (shown as a solid line, Wn1-(1)) are connected to each other by a neutral line (solid line). In addition, the output point of the second layer of the first division of the U-phase (shown as a dashed line, Un1-(2)), the output point of the second layer of the first division of the V-phase (shown as a dashed line, Vn1-(2)), and the output point of the second layer of the first division of the W-phase (shown as a dashed line, Wn1-(2)) are connected to each other by a neutral line (dashed line).

[0038] The output point of the first layer of the second division of the U-phase (shown by a solid line as Un2-(1)), the output point of the first layer of the second division of the V-phase (shown by a solid line as Vn2-(1)), and the output point of the first layer of the second division of the W-phase (shown by a solid line as Wn2-(1)) are all connected to each other by a neutral line (solid line). Furthermore, the output point of the second layer of the second division of the U-phase (shown by a dashed line as Un2-(2)), the output point of the second layer of the second division of the V-phase (shown by a dashed line as Vn2-(2)), and the output point of the second layer of the second division of the W-phase (shown by a dashed line as Wn2-(2)) are all connected to each other by a neutral line (dashed line).

[0039] <Laminated structure of the coil section> Figure 4 is a cross-sectional view of an example of the laminated structure of the coil section 61 in the stator 3 according to the embodiment, viewed from the axial direction. Figure 4 corresponds to a view of the stator 3 when the axial central side is cut by a plane perpendicular to the axial direction. Referring together to Figures 2 to 4, each of the plurality of coil sections 61 has a first layer 61L1 and a second layer 61L2.

[0040] The first layer portion 61L1 is arranged along the outer circumference of the teeth 42 from one end side to the other end side in the protruding direction PD of the teeth 42. The protruding direction PD of the teeth 42 corresponds to the radial direction of the stator 3. In the example of Fig. 4, the teeth 42 extend such that the circumferential width gradually decreases from one end side in the protruding direction PD (the radially outer end side) toward the other end side (the radially inner end side), and then protrudes outward in the circumferential direction on the other end side. Further, the insulator main body portion 50 (intermediate insulator 56) extends along the outer circumferential surface of the teeth 42 from the radially outer end side toward the radially inner end side, and then extends while curving outward in the circumferential direction on the inner end side.

[0041] It should be noted that the teeth 42 may extend with a constant width from one end side in the protruding direction PD (the radially outer end side) to the other end side (the radially inner end side). For example, one circumferential end face and the other circumferential end face of the teeth 42 may be configured to be parallel to each other. The configuration of the teeth 42 can be changed according to design specifications.

[0042] In the example of Fig. 4, the first layer portion 61L1 is arranged along the outer circumference of the teeth 42 via the insulator main body portion 50. The first layer portion 61L1 extends with a constant width (in the illustrated example, the circumferential width when three strands 60W are closely arranged in the circumferential direction) from a portion on one end side (the radially outer end side) in the protruding direction PD of the teeth 42 to the other end side (the radially inner end side) in the insulator main body portion 50, and then is shifted outward in the circumferential direction by a predetermined width (one strand 60W in the illustrated example) along the curved portion of the insulator main body portion 50.

[0043] The second layer portion 61L2 is arranged on the outer circumferential side of the first layer portion 61L1. Similar to the first layer portion 61L1, the second layer portion 61L2 is arranged along the outer circumference of the first layer portion 61L1 from one end side to the other end side in the protruding direction PD of the teeth 42.

[0044] In the example of FIG. 4, the second layer portion 61L2 is arranged along the outer periphery of the teeth 42 via the insulator main body portion 50 and the first layer portion 61L1. The second layer portion 61L2 extends from a portion on one end side (radially outer end side) in the protruding direction PD of the teeth 42 in the first layer portion 61L1 to the other end side (radially inner end side) with a constant width (in the illustrated example, the width in the circumferential direction when three strands 60W are closely arranged in the circumferential direction), and then the circumferential width is narrowed by a predetermined width (two strands 60W in the illustrated example) along the shifted portion of the first layer portion 61L1.

[0045] The number of strands 60W constituting the multi-strand wire 60M in the first layer portion 61L1 may be less than the number of strands 60W constituting the multi-strand wire 60M in the second layer portion 61L2. The wire diameter D1 of the strand 60W constituting the multi-strand wire 60M in the first layer portion 61L1 may be smaller than the wire diameter D2 of the strand 60W constituting the multi-strand wire 60M in the second layer portion 61L2.

[0046] In the present embodiment, the number of turns of the winding 6 in the first layer portion 61L1 and the number of turns of the winding 6 in the second layer portion 61L2 are the same as each other. The number of turns of the winding 6 in the first layer portion 61L1 means the number of times the winding 6 is wound along the outer periphery of the teeth 42 in the first layer portion 61L1. The number of turns of the winding 6 in the second layer portion 61L2 means the number of times the winding 6 is wound along the outer periphery of the first layer portion 61L1 in the second layer portion 61L2.

[0047] FIG. 7 is a circuit diagram showing an example of a three-phase AC circuit in the case of two parallel two windings in the stator according to the embodiment. In FIG. 7, (1) and (2) indicate one turn (first layer) and two turns (second layer) of each phase, respectively. In the example shown in FIG. 7, the three phase windings 6U, 6V, 6W constitute a three-phase AC circuit in the case of two parallel two windings. In the example shown in FIG. 7, in the connection between the phase windings 6U, 6V, 6W having different phases from each other, the neutral points of the first layer portion and the second layer portion of each parallel circuit are shared.

[0048] In the example shown in Figure 7, the three phase windings 6U, 6V, and 6W constitute a three-phase AC circuit in the case of two parallel, two-turn windings, but it is sufficient that the number of parallel circuits is even. When the number of parallel windings 6 is p and α is a natural number, it is sufficient that the condition p = 2α is satisfied. Also, when the number of parallel windings 6 is p and N is the number of neutral points, it is sufficient that the condition N = p is satisfied.

[0049] The number of turns in the winding in the first layer and the number of turns in the winding in the second layer may be the same. Also, the wire diameters of the strands that make up the coil portion wound around each tooth may be the same.

[0050] Note that while Figure 7 shows two parallel circuits as an example, this method is also applicable to four, six, or more parallel circuits. The effect of suppressing circulating current increases as the number of parallel circuits increases.

[0051] <Effects and Effects> As described above, the stator 3 of this embodiment comprises an annular stator core 4 having a plurality of slots 43 arranged in the circumferential direction and a plurality of teeth 42 formed between adjacent slots 43 and protruding radially, and a plurality of windings 6 wound around the plurality of teeth 42. Each of the plurality of windings 6 is a multi-strand wire 60M made up of a bundle of a plurality of strands 60W, and is provided in parallel with each other. Each of the plurality of windings 6 has a plurality of coil portions 61 wound around the teeth 42 by concentrated winding. Each of the plurality of coil portions 61 has a first layer portion 61L1 arranged along the outer circumference of the teeth 42 from one end to the other in the protruding direction PD of the teeth 42, and a second layer portion 61L2 arranged on the outer circumference side of the first layer portion 61L1. For example, a comparative example is when the plurality of coil portions 61 are provided arranged in the protruding direction PD of the teeth 42. In the comparative example, the coil portions 61 wound around the outer and inner portions of the teeth 42 in the protruding direction PD partially overlap in a direction intersecting the protruding direction PD, which can cause winding collapse of the winding 6. In this case, large localized gaps may occur, potentially reducing the space factor. In contrast, in this embodiment, each of the multiple coil portions 61 has a first layer portion 61L1 arranged along the outer circumference of the teeth 42 from one end to the other in the protruding direction PD, and a second layer portion 61L2 arranged on the outer circumference side of the first layer portion 61L1. This creates a laminated structure along the outer circumference of the teeth 42, making it less likely for large localized gaps to occur. Therefore, a stator 3 that can suppress a reduction in space factor can be provided.

[0052] In this embodiment, the number of strands 60W constituting the multi-strand wire 60M in the first layer 61L1 may be less than the number of strands 60W constituting the multi-strand wire 60M in the second layer 61L2. With this configuration, the resistance difference between the first layer 61L1 and the second layer 61L2 can be reduced under predetermined conditions, making it difficult for circulating current to flow. Therefore, a decrease in efficiency can be suppressed.

[0053] In this embodiment, the wire diameter D1 of the strands 60W constituting the multi-strand wire 60M in the first layer 61L1 may be smaller than the wire diameter D2 of the strands 60W constituting the multi-strand wire 60M in the second layer 61L2. With this configuration, the resistance difference between the first layer 61L1 and the second layer 61L2 can be reduced under predetermined conditions, making it difficult for circulating current to flow. Therefore, a decrease in efficiency can be suppressed.

[0054] In this embodiment, the number of turns of the winding 6 in the first layer 61L1 and the number of turns of the winding 6 in the second layer 61L2 are the same. With this configuration, it is easier to wind the winding 6 compared to the case where the number of turns of the winding 6 in the first layer 61L1 and the number of turns of the winding 6 in the second layer 61L2 are different, and therefore easier to manufacture the stator 3.

[0055] In this embodiment, the motor 1 comprises a rotor 2 and the stator 3 described above. With this configuration, a more efficient motor 1 can be realized by providing a stator that can suppress the reduction in the packing factor. In addition, it becomes possible to wind multiple strands 60W, resulting in a more efficient motor 1. Furthermore, since the multiple strands 60M are wound in multiple sections, a smaller wire size can be selected, allowing for tighter winding and resulting in a high packing factor winding. Moreover, the generation of potential differences between parallel circuits, which are often conflicting, can be minimized, thereby suppressing circulating current within the parallel circuit. Therefore, a more efficient motor 1 can be realized.

[0056] For example, there are techniques to reduce the resistance difference between parallel circuits, such as dividing the coil area or devising ways to make the circumferences the same length. However, in the case of multi-spindle winding, it is difficult to control the number of strands, and doing so may conversely lead to a decrease in the space factor. In contrast, according to this embodiment, instead of making the circumferences the same to reduce the resistance difference between parallel circuits, it is possible to reduce the resistance difference between parallel circuits while assuming that the circumferences will vary.

[0057] Incidentally, there is a winding method called multi-strand winding that pursues even higher performance. For example, when winding a large motor in a concentrated manner, the key technology that determines the motor performance is how many strands (number of wires) can be wound by selecting an easy-to-handle wire diameter. Multi-strand winding has equipment limitations because it involves holding multiple strands of wire with a nozzle while maintaining a specified tension during winding. In order to wind more strands (number of wires) into a slot, a winding method with two or more turns is required. However, with two or more turns of winding, the average circumference length in the slot differs between the first turn (first layer) and the second turn (second layer), which can cause a potential difference. Therefore, when a parallel circuit is formed with one turn (first layer) and two turn (second layer), a circulating current may be generated in that section, which can reduce motor efficiency. In contrast, according to this embodiment, as described above, even with two or more turns of winding, the resistance difference between parallel circuits can be reduced, thus suppressing the decrease in motor efficiency. For example, first, a combination is selected that is close to the total number of wires in the slot that results in a high packing factor (total number of wires × number of turns). Next, for the single-turn (first layer) and double-turn (second layer) windings, a combination is selected that sets the cross-sectional area, i.e., the number of wires, to cancel out the difference, based on the level (results of prior studies) where the potential difference (or difference in circumference or resistance) is minimized. This makes it possible to realize a more efficient motor by achieving a high packing factor while suppressing circulating current.

[0058] <Second Embodiment> Figure 8 is a circuit diagram showing an example of a three-phase AC circuit in the stator according to the second embodiment, where there are two parallel windings with two turns. Figure 9 is a circuit diagram showing an improved example of a three-phase AC circuit in the stator according to the second embodiment, where there are two parallel windings with two turns. Figure 10 is a diagram showing an example of a winding connection diagram in the improved example of a three-phase AC circuit in the stator according to the second embodiment, where there are two parallel windings with two turns, separated into U-phase, V-phase, and W-phase. In Figures 8 to 9, the one-turn (first layer) and two-turn (second layer) windings of each phase are indicated by (1) and (2), respectively. The stator according to the second embodiment will be described below with reference to Figures 8 to 10. In the configurations shown in Figures 8 to 10, the same reference numerals are used for components similar to those in the embodiments described above, and their detailed descriptions are omitted.

[0059] In the example shown in Figure 8, when connecting phase windings 6U, 6V, and 6W that are in different phases, the same layers within the same phase that constitute the same phase winding are connected in parallel. In the example shown in Figure 8, the same layers wound on different teeth are connected so that the resistance within the same phase is the same. In the example shown in Figure 8, even in relation to other different phases, the same layers are connected via independent neutral points N1 and N2. In the example shown in Figure 8, a difference in resistance between small and large (resistance difference between wires) occurs between different phases, so circulating current can occur between the wires.

[0060] In the example shown in Figure 9, the three phase windings 6U, 6V, and 6W constitute a three-phase AC circuit in the case of two parallel, two-turn windings, and show an improved example that suppresses the generation of circulating current as in the example shown in Figure 8. In the example shown in Figure 9, when connecting phase windings 6U, 6V, and 6W that are in different phases, the same layers that constitute the same phase winding are connected in parallel. In the example shown in Figure 9, the same layers wound on different teeth are connected so that the resistance within the same phase is the same. In the example shown in Figure 9, when connecting phase windings 6U, 6V, and 6W that are in different phases, in relation to other different phases, different layers are connected to each other via independent neutral points N1 and N2.

[0061] In the example shown in Figure 9, the first layer constituting the first phase winding 6U (specifically, the first layer wound around a predetermined tooth from among a plurality of different teeth in the first phase, and the first layer wound around a tooth other than the predetermined tooth in the first phase), the second layer constituting the second phase winding 6V (specifically, the second layer wound around a predetermined tooth from among a plurality of different teeth in the second phase, and the second layer wound around a tooth other than the predetermined tooth in the second phase), and the second layer constituting the third phase winding 6W (specifically, the second layer wound around a predetermined tooth from among a plurality of different teeth in the third phase, and the second layer wound around a tooth other than the predetermined tooth in the third phase) are connected to each other via a first neutral point. The second layer portion constituting the first phase winding 6U (specifically, the second layer portion wound around a predetermined tooth from among a plurality of different teeth in the first phase, and the second layer portion wound around a tooth other than the predetermined tooth in the first phase), the first layer portion constituting the second phase winding 6V (specifically, the first layer portion wound around a predetermined tooth from among a plurality of different teeth in the second phase, and the first layer portion wound around a tooth other than the predetermined tooth in the second phase), and the first layer portion constituting the third phase winding 6W (specifically, the first layer portion wound around a predetermined tooth from among a plurality of different teeth in the third phase, and the first layer portion wound around a tooth other than the predetermined tooth in the third phase) are connected to each other via a second neutral point different from the first neutral point.

[0062] In the example shown in Figures 8 and 9, the three phase windings 6U, 6V, and 6W constitute a three-phase AC circuit in the case of two parallel, two-turn windings, but it is sufficient that the number of parallel circuits is even. When the number of parallel windings 6 is p and α is a natural number, it is sufficient that the condition p = 2α is satisfied. Also, when the number of parallel windings 6 is p and N is the number of neutral points, it is sufficient that the condition N = p is satisfied.

[0063] The number of turns in the winding in the first layer and the number of turns in the winding in the second layer may be the same. Also, the wire diameters of the strands that make up the coil portion wound around each tooth may be the same.

[0064] Note that while the examples shown in Figures 8 and 9 use two parallel circuits as an example, this method is also applicable to four, six, or more parallel circuits. The effect of suppressing circulating current increases as the number of parallel circuits increases.

[0065] Figure 10 shows an example of a winding diagram for an improved three-phase AC circuit with two parallel, double-wound windings, divided into U-phase, V-phase, and W-phase. In Figure 10, the stator 3 is laid out linearly so that its circumferential direction extends in the left-right direction, and the teeth 42 of the stator 3, the three connecting grooves 52 of the insulator 5, etc. are schematically shown. An example of a winding diagram for the winding 6 is also shown, divided into three parts: U-phase, V-phase, and W-phase. Furthermore, because it is two parallel, double-wound, the winding 6 for each phase is divided into two parts in the circumferential direction of the stator 3.

[0066] Each of the multiple windings 6 has multiple coil sections 61, at least one jumper section 62, and two lead sections 63. In the same winding 6, each of the multiple coil sections 61 is wound around the teeth 42 by concentrated winding. In Figure 10, the coil sections 61 are shown surrounding the teeth 42 from below, but in reality, they are wound around the teeth 42 by concentrated winding.

[0067] The jumper wires 62 connect adjacent coil sections 61 in multiple coil sections 61 (in the example shown in Figure 10, the coil sections 61 of the U-phase winding 6U (first-phase winding), the coil sections 61 of the V-phase winding 6V (second-phase winding), and the coil sections 6W (second-phase winding)). The number of jumper wires 62 is one less than the number of coil sections 61. The two lead wires 63 form the ends of the same winding 6. The two lead wires 63 extend from the coil section 61.

[0068] In the stator 3, the coil sections 61 of the U-phase winding 6U, the V-phase winding 6V, and the W-phase winding 6W are arranged in a repeating sequence in the circumferential direction. Therefore, the coil sections 61 of windings 6 of the same phase are wound around teeth 42, which are arranged every three teeth. The example in Figure 10 shows the case where there are 12 slots. In the example in Figure 10, in each parallel circuit of each phase, a single turn (first layer) is shown as a solid line winding, and a double turn (second layer) is shown as a dashed line winding.

[0069] In the example shown in Figure 10, in each parallel U-phase circuit, the two coil sections 61 (solid and dashed windings) of the U-phase winding 6U, which is wound around the first division (the first of two divisions), are wound around the first and fourth teeth 42 (42-1, 42-4). In each parallel U-phase circuit, the two coil sections 61 (solid and dashed windings) of the U-phase winding 6U, which is wound around the second division (the second of two divisions), are wound around the seventh and tenth teeth 42 (42-7, 42-10). In each parallel V-phase circuit, the two coil sections 61 (solid and dashed windings) of the V-phase winding 6V, which is wound around the first division, are wound around the second and fifth teeth 42 (42-2, 42-5). In each parallel V-phase circuit, the two coil sections 61 (solid and dashed windings) of the V-phase winding 6V, which is wound in the second division, are wound around the 8th and 11th teeth 42 (42-8, 42-11). In each parallel W-phase circuit, the two coil sections 61 (solid and dashed windings) of the W-phase winding 6W, which is wound in the first division, are wound around the 3rd and 6th teeth 42 (42-3, 42-6). In each parallel W-phase circuit, the two coil sections 61 (solid and dashed windings) of the W-phase winding 6W, which is wound in the second division, are wound around the 9th and 12th teeth 42 (42-9, 42-12). In the example in Figure 10, the U-phase coil section 61U, the V-phase coil section 61V, and the W-phase coil section 61W are arranged in a repeating order to the right (first rotation direction RD1). Therefore, the numbers on teeth 42, as mentioned above, are arranged sequentially from left to right.

[0070] Furthermore, the jumper wire portion 62 of the U-phase winding 6U is housed in the U-phase jumper groove 52U. Similarly, the jumper wire portion 62 of the V-phase winding 6V is housed in the V-phase jumper groove 52V. The jumper wire portion 62 of the W-phase winding 6W is housed in the W-phase jumper groove 52W.

[0071] In the stator 3 illustrated in Figure 10, in each parallel circuit of each phase, the second end of each winding 6 wound in the first division, which is located opposite the first end that forms the input points U1 (U1-(1) shown as a solid line, U1-(2) shown as a dashed line), V1 (V1-(1) shown as a solid line, V1-(2) shown as a dashed line), and W1 (W1-(1) shown as a solid line, W1-(2) shown as a dashed line), is the output point Un1 (Un1-(1) shown as a solid line, Un1-(2) shown as a dashed line), Vn1 (Vn1-(1) shown as a solid line, Vn1-(2) shown as a dashed line), and Wn1 (Wn1-(1) shown as a solid line, Wn1-(2) shown as a dashed line). In each parallel circuit of each phase, the second end of each winding 6 that is wound around the second division, opposite to the first end which forms the input points U2 (U2-(1) shown as a solid line, U2-(2) shown as a dashed line), V2 (V2-(1) shown as a solid line, V2-(2) shown as a dashed line), and W2 (W2-(1) shown as a solid line, W2-(2) shown as a dashed line), is the output point Un2 (Un2-(1) shown as a solid line, Un2-(2) shown as a dashed line), Vn2 (Vn2-(1) shown as a solid line, Vn2-(2) shown as a dashed line), and Wn2 (Wn2-(1) shown as a solid line, Wn2-(2) shown as a dashed line).

[0072] The three-phase output points Un1 (shown as a solid line, Un1-(1)), Vn1 (shown as a dashed line, Vn1-(2)), Wn1 (shown as a dashed line, Wn1-(2)), and output points Un2 (shown as a solid line, Un2-(1)), Vn2 (shown as a dashed line, Vn2-(2)), and Wn2 (shown as a dashed line, Wn2-(2)) constitute the neutral point N1 of the connection shown in Figure 9. The three-phase output points Un1 (shown as a dashed line, Un1-(2)), Vn1 (shown as a solid line, Vn1-(1)), Wn1 (shown as a solid line, Wn1-(1)), and output points Un2 (shown as a dashed line, Un2-(2)), Vn2 (shown as a solid line, Vn2-(1)), and Wn2 (shown as a solid line, Wn2-(1)) constitute the neutral point N2 of the connection shown in Figure 9.

[0073] In the example shown in Figure 10, the first layer (solid line) and the second layer (dashed line), wound around different teeth in the same phase, are connected to each other by a neutral wire (neutral point connection) so that they form independent parallel circuits. The neutral point connections for each of the three phases result in coils of different layers, and when viewed between the wires, the first layer (solid line) and the second layer (dashed line) form a pair.

[0074] Specifically, the output point of the first layer of the first division of the U-phase (shown by a solid line as Un1-(1)), the output point of the second layer of the first division of the V-phase (shown by a dashed line as Vn1-(2)), and the output point of the first layer of the first division of the W-phase (shown by a solid line as Wn1-(1)) are all connected to each other by a neutral line (solid line). In addition, the output point of the second layer of the first division of the U-phase (shown by a dashed line as Un1-(2)), the output point of the first layer of the first division of the V-phase (shown by a solid line as Vn1-(1)), and the output point of the second layer of the first division of the W-phase (shown by a dashed line as Wn1-(2)) are all connected to each other by a neutral line (dashed line).

[0075] The output point of the first layer of the second division of the U-phase (shown by a solid line as Un2-(1)), the output point of the second layer of the second division of the V-phase (shown by a dashed line as Vn2-(2)), and the output point of the first layer of the second division of the W-phase (shown by a solid line as Wn2-(1)) are all connected to each other by a neutral line (solid line). Additionally, the output point of the second layer of the second division of the U-phase (shown by a dashed line as Un2-(2)), the output point of the first layer of the second division of the V-phase (shown by a solid line as Vn2-(1)), and the output point of the second layer of the second division of the W-phase (shown by a dashed line as Wn2-(2)) are all connected to each other by a neutral line (dashed line).

[0076] <Explanation of Circulating Current> In a two-parallel circuit with a double-turn winding, circulating current may occur between phases or between wires. Let Ra1 and Ra2 be the phase resistances of the first turn (first layer) and the second turn (second layer) of the first phase (e.g., U phase), respectively. Let Rb1 and Rb2 be the phase resistances of the first turn (first layer) and the second turn (second layer) of the second phase (e.g., V phase), respectively. Since the average circumference of the multi-strand wires wound around the teeth 42 differs between the first turn (first layer) and the second turn (second layer), this is shown by the following equations (2-1) and (2-2). (Equation (2-1)) Ra1 ≠ Ra2 (Equation (2-2)) Rb1 ≠ Rb2

[0077] On the other hand, when the phases are different, the phase resistances may be approximately the same, as shown in the following equations (2-3) and (2-4). (Equation (2-3)) Ra1 ≈ Rb1 (Equation (2-4)) Ra2 ≈ Rb2

[0078] Since the inter-line resistance Rab (for example, the resistance of the UV phase) exists for each parallel circuit, when the inter-line resistance of one parallel circuit is Rab1 and the inter-line resistance of the other is Rab2, it is given by the following equations (2-5) and (2-6): (Equation (2-5)) Rab1 = Ra1 + Rb1 (Equation (2-6)) Rab2 = Ra2 + Rb2

[0079] By connecting identical layers wound on different teeth so that the resistance within the same phase is the same, the generation of interphase circulating current can be suppressed.

[0080] If equations (2-1) and (2-2) above are satisfied, then equations (2-5) and (2-6) above lead to the following equation (2-7). (Equation (2-7)) Rab1 ≠ Rab2

[0081] When equation (2-7) above is satisfied, a difference in resistance between different phases (a resistance difference between wires) occurs between the small and large resistances, which can cause circulating current to be generated between the wires.

[0082] On the other hand, if equations (2-3) and (2-4) above are satisfied, then equations (2-5) and (2-6) above lead to the following equation (2-8). (Equation (2-8)) Rab1 ≈ Rab2

[0083] When equation (2-8) above is satisfied, the difference between combinations of small and large resistances between different phases becomes the result, and the resistance between the wires becomes approximately the same, thus suppressing the generation of circulating current between the wires.

[0084] As described above, in this embodiment, the multiple windings 6 include multiple phase windings 6U, 6V, and 6W that are in different phases from each other. Either one of the first layer 61L1 and the second layer 61L2 that constitute one of the multiple phase windings 6U, 6V, and 6W is connected in parallel to the same layer of the first layer 61L1 and second layer 61L2 that constitute the same phase winding as the aforementioned one. For example, when multiple phase windings that are in different phases are connected, if the neutral point of the first layer and the second layer of each parallel circuit is made common, a circulating current may occur between the phases because the resistance values ​​of the first layer and the second layer are different. In contrast, with this configuration, when multiple phase windings 6U, 6V, and 6W that are in different phases are connected, the same layers that constitute the same phase winding are connected in parallel to each other within the same phase. This makes it possible to reduce the resistance difference (potential difference) within the same phase, thus making it difficult for a circulating current to flow. Therefore, the decrease in efficiency can be suppressed.

[0085] In this embodiment, the multiple phase windings 6U, 6V, and 6W include a first phase winding 6U, a second phase winding 6V, and a third phase winding 6W, which are in different phases from each other. The first layer 61L1 constituting the first phase winding 6U, the second layer 61L2 constituting the second phase winding 6V, and the second layer 61L2 constituting the third phase winding 6W are connected to each other via a first neutral point. The second layer 61L2 constituting the first phase winding 6U, the first layer 61L1 constituting the second phase winding 6V, and the first layer 61L1 constituting the third phase winding 6W are connected to each other via a second neutral point different from the first neutral point. For example, in the connection of multiple phase windings that are in different phases from each other, if the same layers are connected in parallel within the same phase that constitutes the same phase winding, a resistance difference will occur between the wires, which may cause a circulating current to occur between the wires. In contrast, with this configuration, in the connection of the three phase windings 6U, 6V, and 6W, different layers 61L1 and 61L2 are connected to each other via independent neutral points. This minimizes the resistance difference (potential difference) between the lines, thus making it difficult for circulating current to flow. Therefore, with this configuration, it is possible to suppress the generation of circulating current between lines while suppressing the generation of circulating current between the same phases. Consequently, efficiency degradation can be suppressed more effectively.

[0086] <Third Embodiment> Figure 11 is a cross-sectional view from the axial direction of an example of the coil stacking structure in the stator according to the third embodiment. Figure 12 is a circuit diagram showing an improved example 2 of a three-phase AC circuit in the case of three parallel windings in the stator according to the third embodiment. Figure 13 is a diagram showing an example of a winding connection diagram in a three-phase AC circuit in the case of three parallel windings in the stator according to the third embodiment, divided into U-phase, V-phase, and W-phase. In Figure 12, the one-turn (first layer), two-turn (second layer), and three-turn (third layer) windings of each phase are indicated by (1), (2), and (3), respectively. The stator according to the third embodiment will be described below with reference to Figures 11 to 13. In the configurations shown in Figures 11 to 13, the same reference numerals are used for components similar to those in the embodiments described above, and their detailed explanations are omitted.

[0087] Figure 11 corresponds to a view of the stator 3 when the axial central side is cut by a plane perpendicular to the axial direction. In the example of Figure 11, a cross-sectional view of the intermediate insulator 56 (axial central side of the insulator body 50) is shown. Referring to Figure 11, each of the plurality of coil portions 61 has a first layer portion 61L1, a second layer portion 61L2, and a third layer portion 61L3. In this embodiment, each of the plurality of coil portions 61 further has a third layer portion 61L3 arranged on the outer circumference side of the second layer portion 61L2.

[0088] In the example shown in Figure 11, the first layer 61L1 is arranged along the outer circumference of the teeth 42 via the insulator body 50. The first layer 61L1 extends from one end (the inner radial end) to the other end (the outer radial end) of the teeth 42 in the protruding direction PD of the insulator body 50 with a constant width (in the illustrated example, the width in the circumferential direction when two strands 60W are arranged in close contact in the circumferential direction), and then shifts outward in the circumferential direction by a predetermined width (in the illustrated example, one strand 60W) to follow the curved portion of the insulator body 50.

[0089] The second layer 61L2 is positioned along the outer circumference of the teeth 42 via the insulator body 50 and the first layer 61L1. The second layer 61L2 extends from one end (the inner radial end) to the other end (the outer radial end) of the teeth 42 in the protruding direction PD of the first layer 61L1 with a constant width (in the illustrated example, the width in the circumferential direction when two strands 60W are arranged in close contact in the circumferential direction), and then shifts outward in the circumferential direction by a predetermined width (in the illustrated example, one strand 60W) along the shifted portion of the first layer 61L1.

[0090] The third layer 61L3 is arranged along the outer circumference of the teeth 42 via the insulator body 50, the first layer 61L1, and the second layer 61L2. The third layer 61L3 extends from one end (the inner radial end) to the other end (the outer radial end) of the teeth 42 in the protruding direction PD of the second layer 61L2 with a constant width (in the illustrated example, the width in the circumferential direction when two strands 60W are arranged in close contact in the circumferential direction), and then its circumferential width is narrowed by a predetermined width (in the illustrated example, one strand 60W) to follow the offset portion of the second layer 61L2.

[0091] In the example shown in Figure 12, when connecting phase windings 6U, 6V, and 6W that are in different phases, the same layers within the same phase that constitute the same phase winding are connected in parallel. In the example shown in Figure 12, the same layers wound on different teeth are connected so that the resistance within the same phase is the same. In the example shown in Figure 12, when connecting phase windings 6U, 6V, and 6W that are in different phases, the connection between the first layer and the third layer, and the connection between the second layers, are made via independent neutral points in relation to other different phases.

[0092] In the example shown in Figure 12, the first layer portion constituting the first phase winding 6U (specifically, each first layer portion wound around multiple different teeth in the first phase), the second layer portion constituting the second phase winding 6V (specifically, each third layer portion wound around multiple different teeth in the second phase), and the third layer portion constituting the third phase winding 6W (specifically, each third layer portion wound around multiple different teeth in the third phase) are connected to each other via a first neutral point. The second layers constituting the first phase winding 6U (specifically, each second layer wound around multiple different teeth in the first phase), the second layers constituting the second phase winding 6V (specifically, each second layer wound around multiple different teeth in the second phase), and the second layers constituting the third phase winding 6W (specifically, each second layer wound around multiple different teeth in the third phase) are connected to each other via a second neutral point different from the first neutral point. The third layer portion constituting the first phase winding 6U (specifically, each third layer portion wound around multiple different teeth in the first phase), the first layer portion constituting the second phase winding 6V (specifically, each first layer portion wound around multiple different teeth in the second phase), and the first layer portion constituting the third phase winding 6W (specifically, each first layer portion wound around multiple different teeth in the third phase) are connected to each other via a third neutral point different from the first and second neutral points. Thus, in the example shown in Figure 12, in the connection of the three phase windings 6U, 6V, and 6W to each other, the connections to other different phases are the connections between the first and third layers, and the connections between the second layers, and are connected to each other via independent neutral points.

[0093] In the example shown in Figure 12, the three phase windings 6U, 6V, and 6W constitute a three-phase AC circuit with three parallel turns, but it is sufficient that the number of parallel circuits be a multiple of three. When the number of parallel windings 6 is p and α is a natural number, the condition p = 3α is satisfied. Also, when the number of parallel windings 6 is p and N is the number of neutral points, the condition N = p is satisfied.

[0094] The number of turns in the first layer, the second layer, and the third layer may all be the same. Furthermore, the wire diameters of the strands constituting the coil section wound around each tooth may all be the same.

[0095] Note that while Figure 12 shows an example with three parallel circuits, this method is also applicable to six, nine, or more parallel circuits. The effect of suppressing circulating current increases with the number of parallel circuits.

[0096] In the example shown in Figure 13, an example of the winding connection diagram for the U-phase, V-phase, and W-phase is shown separately for the U-phase and V-phase in the case of three parallel, three-turn windings in Improvement Example 2 of a three-phase AC circuit. In Figure 13, the stator 3 is unfolded linearly so that the circumferential direction of the stator 3 extends in the left-right direction, and the teeth 42 of the stator 3, the three connecting grooves 52 of the insulator 5, etc. are schematically shown. An example of the winding connection diagram for the winding 6 is also shown separately for the U-phase, V-phase, and W-phase. Furthermore, because it is three parallel, three-turn windings, the winding 6 for each phase is divided into three parts in the circumferential direction of the stator 3.

[0097] Each of the multiple windings 6 has multiple coil sections 61, at least one jumper section 62, and two lead-out sections 63. In the same winding 6, each of the multiple coil sections 61 is wound around the teeth 42 by concentrated winding. In Figure 13, the coil sections 61 are shown surrounding the teeth 42 from below, but in reality, they are wound around the teeth 42 by concentrated winding.

[0098] The jumper wires 62 connect adjacent coil sections 61 in multiple coil sections 61 (in the example shown in Figure 13, the coil sections 61 of the U-phase winding 6U (first-phase winding), the coil sections 61 of the V-phase winding 6V (second-phase winding), and the coil sections 6W (third-phase winding)). The number of jumper wires 62 is one less than the number of coil sections 61. The two lead wires 63 form the ends of the same winding 6. The two lead wires 63 extend from the coil section 61.

[0099] In the stator 3, the coil sections 61 of the U-phase winding 6U, the V-phase winding 6V, and the W-phase winding 6W are arranged in a repeating sequence in the circumferential direction. Therefore, the coil sections 61 of windings 6 of the same phase are wound around teeth 42, which are arranged every three teeth. The example in Figure 13 shows the case where there are 18 slots. In the example in Figure 13, in each parallel circuit of each phase, one turn (first layer) is shown as a solid line winding, two turns (second layer) as a dashed line winding, and three turns (third layer) as a dotted-dotted line winding.

[0100] In the example shown in Figure 13, in each parallel U-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the U-phase winding 6U that are wound around the first division (the first of three divisions) are wound around the first and fourth teeth 42 (42-1, 42-4). In each parallel U-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the U-phase winding 6U that are wound around the second division (the second of three divisions) are wound around the seventh and tenth teeth 42 (42-7, 42-10). In each parallel circuit of the U-phase, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the U-phase winding 6U, which is wound around the third division (the third of the three divisions), are wound around the 13th and 16th teeth 42 (42-13, 42-16).

[0101] In each parallel V-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the V-phase winding 6V wound in the first division are wound around the second and fifth teeth 42 (42-2, 42-5). In each parallel V-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the V-phase winding 6V wound in the second division are wound around the eighth and eleventh teeth 42 (42-8, 42-11). In each parallel V-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the V-phase winding 6V wound in the third division are wound around the fourteenth and seventeenth teeth 42 (42-14, 42-17).

[0102] In each parallel W-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the W-phase winding 6W wound in the first division are wound around the third and sixth teeth 42 (42-3, 42-6). In each parallel W-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the W-phase winding 6W wound in the second division are wound around the ninth and twelfth teeth 42 (42-9, 42-12). In each parallel W-phase circuit, the two coil sections 61 (solid line winding, dashed line winding, and dotted line winding) of the W-phase winding 6W wound in the third division are wound around the fifteenth and eighteenth teeth 42 (42-15, 42-18). In the example shown in Figure 13, the U-phase coil section 61U, the V-phase coil section 61V, and the W-phase coil section 61W are arranged in a repeating sequence to the right (first circumferential direction RD1). Therefore, the numbers of the teeth 42 mentioned above are arranged sequentially from the left end to the right.

[0103] Furthermore, the jumper wire portion 62 of the U-phase winding 6U is housed in the U-phase jumper groove 52U. Similarly, the jumper wire portion 62 of the V-phase winding 6V is housed in the V-phase jumper groove 52V. The jumper wire portion 62 of the W-phase winding 6W is housed in the W-phase jumper groove 52W.

[0104] In the stator 3 illustrated in Figure 13, in each parallel circuit of each phase, among the windings 6 wound in the first division, the input points U1 (U1-(1) shown as a solid line, U1-(2) shown as a dashed line, U1-(3) shown as a dotted line), V1 (V1-(1) shown as a solid line, V1-(2) shown as a dashed line, V1-(3) shown as a dotted line), W1 (W1-(1) shown as a solid line, W1-(2) shown as a dashed line, W1 The second end, located on the opposite side of the first end which forms (3), is the output point Un1 (Un1-(1) shown by a solid line, Un1-(2) shown by a dashed line, Un1-(3) shown by a dotted line), Vn1 (Vn1-(1) shown by a solid line, Vn1-(2) shown by a dashed line, Vn1-(3) shown by a dotted line), and Wn1 (Wn1-(1) shown by a solid line, Wn1-(2) shown by a dashed line, Wn1-(3) shown by a dotted line). In each parallel circuit of each phase, among the windings 6 that are wound around the second division, the input points U2 (U2-(1) shown as a solid line, U2-(2) shown as a dashed line, U2-(3) shown as a dotted line), V2 (V2-(1) shown as a solid line, V2-(2) shown as a dashed line, V2-(3) shown as a dotted line), and W2 (W2-(1) shown as a solid line, W2-(2) shown as a dashed line, W2-(3) shown as a dotted line) The second end, located on the opposite side of the first end, has output points Un2 (Un2-(1) shown as a solid line, Un2-(2) shown as a dashed line, and Un2-(3) shown as a dotted line), Vn2 (Vn2-(1) shown as a solid line, Vn2-(2) shown as a dashed line, and Vn2-(3) shown as a dotted line), and Wn2 (Wn2-(1) shown as a solid line, Wn2-(2) shown as a dashed line, and Wn2-(3) shown as a dotted line).In each parallel circuit of each phase, the windings 6 that are wound around the third division form the input points U3 (U3-(1) shown as a solid line, U3-(2) shown as a dashed line, U3-(3) shown as a dotted line), V3 (V3-(1) shown as a solid line, V3-(2) shown as a dashed line, V3-(3) shown as a dotted line), and W3 (W3-(1) shown as a solid line, W3-(2) shown as a dashed line, W3-(3) shown as a dotted line). The second end, located on the opposite side of the first end, consists of output points Un3 (Un3-(1) shown as a solid line, Un3-(2) shown as a dashed line, and Un3-(3) shown as a dotted line), Vn3 (Vn3-(1) shown as a solid line, Vn3-(2) shown as a dashed line, and Vn3-(3) shown as a dotted line), and Wn3 (Wn3-(1) shown as a solid line, Wn3-(2) shown as a dashed line, and Wn3-(3) shown as a dotted line).

[0105] The three-phase output points Un1 (shown as a solid line, Un1-(1)), Vn1 (shown as a dashed-dotted line, Vn1-(3)), Wn1 (shown as a dashed-dotted line, Wn1-(3)), output point Un2 (shown as a solid line, Un2-(1)), Vn2 (shown as a dashed-dotted line, Vn2-(3)), Wn2 (shown as a dashed-dotted line, Wn2-(3)), and output point Un3 (shown as a solid line, Un3-(1)), Vn3 (shown as a dashed-dotted line, Vn3-(3)), and Wn3 (shown as a dashed-dotted line, Wn3-(3)) constitute the neutral point N1 of the connection shown in Figure 12. The three-phase output points Un1 (shown as a dashed line, Un1-(2)), Vn1 (shown as a dashed line, Vn1-(2)), Wn1 (shown as a dashed line, Wn1-(2)), output point Un2 (shown as a dashed line, Un2-(2)), Vn2 (shown as a dashed line, Vn2-(2)), Wn2 (shown as a dashed line, Wn2-(2)), and output point Un3 (shown as a dashed line, Un3-(2)), Vn3 (shown as a dashed line, Vn3-(2)), and Wn3 (shown as a dashed line, Wn3-(2)) constitute the neutral point N2 of the connection shown in Figure 12. The three-phase output points Un1 (shown as Un1-(3) with a dashed-dotted line), Vn1 (shown as Vn1-(1) with a solid line), Wn1 (shown as Wn1-(1) with a solid line), Un2 (shown as Un2-(3) with a dashed-dotted line), Vn2 (shown as Vn2-(1) with a solid line), Wn2 (shown as Wn2-(1) with a solid line), and Un3 (shown as Un3-(3) with a dashed-dotted line), Vn3 (shown as Vn3-(1) with a solid line), and Wn3 (shown as Wn3-(1) with a solid line) constitute the neutral point N3 of the connection shown in Figure 12.

[0106] In the example shown in Figure 13, the first layer (solid line), second layer (dashed line), and third layer (dotted line), which are wound around different teeth in the same phase, are connected by a neutral wire (neutral point connection) to form independent parallel circuits. The neutral point connections for each of the three phases are the connection between the first layer and the third layer, and the connection between the second layers. When viewed between the lines, the first layer (solid line) and the third layer (dotted line) form pairs, and the second layers (dashed lines) form pairs.

[0107] Specifically, the output point of the first layer of the first division of the U-phase (shown by a solid line, Un1-(1)), the output point of the third layer of the first division of the V-phase (shown by a dashed-dotted line, Vn1-(3)), and the output point of the third layer of the first division of the W-phase (shown by a dashed-dotted line, Wn1-(3)) are connected to each other by neutral lines (solid and dashed lines). In addition, the output point of the second layer of the first division of the U-phase (shown by a dashed line, Un1-(2)), the output point of the second layer of the first division of the V-phase (shown by a dashed line, Vn1-(2)), and the output point of the second layer of the first division of the W-phase (shown by a dashed line, Wn1-(2)) are connected to each other by neutral lines (dashed lines). Furthermore, the output point of the third layer of the first division of the U phase (shown as Un1-(3) by a dashed line), the output point of the first layer of the first division of the V phase (shown as a solid line, Vn1-(1)), and the output point of the first layer of the first division of the W phase (shown as a solid line, Wn1-(1)) are all connected to each other by neutral lines (dashed and solid lines).

[0108] The output point of the first layer of the second division of the U-phase (shown by a solid line, Un2-(1)), the output point of the third layer of the second division of the V-phase (shown by a dashed line, Vn2-(3)), and the output point of the third layer of the second division of the W-phase (shown by a dashed line, Wn2-(3)) are all connected to each other by neutral lines (solid and dashed lines). Additionally, the output point of the second layer of the second division of the U-phase (shown by a dashed line, Un2-(2)), the output point of the second layer of the second division of the V-phase (shown by a dashed line, Vn2-(2)), and the output point of the second layer of the second division of the W-phase (shown by a dashed line, Wn2-(2)) are all connected to each other by neutral lines (dashed lines). Furthermore, the output point of the third layer of the second division of the U phase (indicated by a dashed line, Un2-(3)), the output point of the first layer of the second division of the V phase (indicated by a solid line, Vn2-(1)), and the output point of the first layer of the second division of the W phase (indicated by a solid line, Wn2-(1)) are all connected to each other by neutral lines (dashed and solid lines).

[0109] The output point of the first layer of the third division of the U-phase (shown by a solid line, Un3-(1)), the output point of the third layer of the third division of the V-phase (shown by a dashed-dotted line, Vn3-(3)), and the output point of the third layer of the third division of the W-phase (shown by a dashed-dotted line, Wn3-(3)) are all connected to each other by neutral lines (solid and dashed lines). Additionally, the output point of the second layer of the third division of the U-phase (shown by a dashed line, Un3-(2)), the output point of the second layer of the third division of the V-phase (shown by a dashed line, Vn3-(2)), and the output point of the second layer of the third division of the W-phase (shown by a dashed line, Wn3-(2)) are all connected to each other by neutral lines (dashed lines). Furthermore, the output point of the third layer of the third division of the U-phase (indicated by a dashed line, Un3-(3)), the output point of the first layer of the third division of the V-phase (indicated by a solid line, Vn3-(1)), and the output point of the first layer of the third division of the W-phase (indicated by a solid line, Wn3-(1)) are all connected to each other by neutral lines (dashed and solid lines).

[0110] <Explanation of circulating current> In a three-turn winding of a three-parallel circuit, circulating current may occur between phases or between wires. Let the phase resistances of the first turn (first layer), the second turn (second layer), and the third turn (third layer) of the first phase (e.g., U phase) be Ra1, Ra2, and Ra3, respectively. Let the phase resistances of the first turn (first layer), the second turn (second layer), and the third turn (third layer) of the second phase (e.g., V phase) be Rb1, Rb2, and Rb3, respectively. Since the average circumference of the multi-wires wound around the teeth 42 differs between the first turn (first layer), the second turn (second layer), and the third turn (third layer), this is shown by the following equations (3-1) and (3-2). (Formula (3-1)) Ra1≠Ra2≠Ra3 (Formula (3-2)) Rb1≠Rb2≠Rb3

[0111] On the other hand, when the phases are different, the phase resistances may be approximately the same, as shown in the following equations (3-3), (3-4), and (3-5). (Equation (3-3)) Ra1 ≈ Rb1 (Equation (3-4)) Ra2 ≈ Rb2 (Equation (3-5)) Ra3 ≈ Rb3

[0112] Since there are as many line resistances Rab (for example, the resistance of the UV phase) as there are parallel circuits, in a 3-parallel circuit, when the line resistance of the first line is Rab1, the line resistance of the second line is Rab2, and the line resistance of the third line is Rab3, the following equations (3-6), (3-7), and (3-8) are given: (Equation (3-6)) Rab1 = Ra1 + Rb3 (Equation (3-7)) Rab2 = Ra2 + Rb2 (Equation (3-8)) Rab3 = Ra3 + Rb1

[0113] By connecting identical layers wound on different teeth so that the resistance within the same phase is the same, the generation of interphase circulating current can be suppressed.

[0114] If equations (3-1) and (3-2) above are satisfied, then equations (3-6), (3-7), and (3-8) above lead to the following equation (3-9): (Equation (3-9)) Rab1 ≠ Rab2 ≠ Rab3

[0115] When equation (3-9) above is satisfied, a difference in resistance between different phases (a resistance difference between wires) occurs between the small and large resistances, which can cause circulating current to be generated between the wires.

[0116] On the other hand, if equations (3-3), (3-4), and (3-5) above are satisfied, then equations (3-6), (3-7), and (3-8) above lead to the following equation (3-10). (Equation (3-10)) Rab1 ≈ Rab2 ≈ Rab3

[0117] When the above equation (3-10) is satisfied, the difference between combinations of small and large resistances between different phases, or the difference between combinations of approximately equal resistances, results in approximately the same resistance between the wires, thus suppressing the generation of circulating current between the wires.

[0118] As described above, in this embodiment, each of the multiple coil sections 61 further has a third layer section 61L3 arranged on the outer circumference of the second layer section 61L2. With this configuration, compared to the case where each of the multiple coil sections 61 has a laminated structure (two-layer structure) having only a first layer section 61L1 and a second layer section 61L2, it is possible to achieve an even higher space factor while suppressing circulating current, thereby realizing a more efficient motor.

[0119] In this embodiment, the multiple windings 6 include multiple phase windings 6U, 6V, and 6W that are in different phases from each other. At least one of the first layer 61L1, second layer 61L2, and third layer 61L3 that constitute one of the multiple phase windings 6U, 6V, and 6W is connected in parallel with at least one of the first layer 61L1, second layer 61L2, and third layer 61L3 that constitute the same phase winding as the aforementioned one. For example, when multiple phase windings that are in different phases are connected, if the neutral point of the first layer, second layer, and third layer of each parallel circuit is made common, a circulating current may occur between phases because the resistance values ​​of each layer are different. In contrast, with this configuration, when multiple phase windings 6U, 6V, and 6W that are in different phases are connected, the same layers that constitute the same phase winding are connected in parallel with each other within the same phase. This reduces the resistance difference (potential difference) within the same phase, making it more difficult for circulating current to flow. Therefore, efficiency degradation can be suppressed.

[0120] In this embodiment, the multiple phase windings 6U, 6V, and 6W include a first phase winding 6U, a second phase winding 6V, and a third phase winding 6W, which are in different phases from each other. The first layer 61L1 constituting the first phase winding 6U, the third layer 61L3 constituting the second phase winding 6V, and the third layer 61L3 constituting the third phase winding 6W are connected to each other via a first neutral point. The second layer 61L2 constituting the first phase winding 6U, the second layer 61L2 constituting the second phase winding 6V, and the second layer 61L2 constituting the third phase winding 6W are connected to each other via a second neutral point different from the first neutral point. The third layer 61L3 constituting the first phase winding 6U, the first layer 61L1 constituting the second phase winding 6V, and the first layer 61L1 constituting the third phase winding 6W are connected to each other via a third neutral point different from the first and second neutral points. For example, when connecting multiple phase windings of different phases, if the same layers within the same phase constituting the same phase winding are connected in parallel, a resistance difference occurs between the lines when other different phases are also connected to the same layers, which can cause circulating current to occur between the lines. In contrast, with this configuration, when connecting the three phase windings 6U, 6V, and 6W, connections to other different phases are made between the first layer 61L1 and the third layer 61L3, and between the second layer 61L2s, and are connected to each other via independent neutral points. This makes it possible to minimize the resistance difference (potential difference) between the lines, thus making it difficult for circulating current to flow. Therefore, this configuration makes it possible to suppress the generation of circulating current between lines while simultaneously suppressing the generation of circulating current between lines. Consequently, efficiency degradation can be suppressed more effectively.

[0121] <Fourth Embodiment> Figure 14 is a circuit diagram showing an example of a three-phase AC circuit in the stator according to the fourth embodiment, where there are two parallel windings with two turns. Figure 15 is a diagram showing an example of a winding connection diagram in the three-phase AC circuit in the stator according to the fourth embodiment, where there are two parallel windings with two turns, separated into U-phase, V-phase, and W-phase. In Figure 14, the one-turn (first layer) and two-turn (second layer) windings of each phase are indicated by (1) and (2), respectively. The stator according to the fourth embodiment will be described below with reference to Figures 14 and 15. In the configurations shown in Figures 14 and 15, the same reference numerals are used for components similar to those in the embodiments described above, and their detailed descriptions are omitted.

[0122] In the example shown in Figure 14, when connecting phase windings 6U, 6V, and 6W that are in different phases, different layers that are wound around different teeth within the same phase, which constitute the same phase winding, are alternately connected in series between the input point and the neutral point of the same phase. In the example shown in Figure 14, different layers wound around different teeth are connected so that the resistance within the same phase is the same. In the example shown in Figure 14, even in relation to other different phases, different layers are alternately connected in series via independent neutral points N1 and N2.

[0123] In the example shown in Figure 14, the first layer constituting the first phase winding 6U (specifically, the first layer wound around a predetermined tooth from among a plurality of teeth that are different from each other in the first phase) and the second layer constituting the first phase winding 6U (specifically, the second layer wound around a tooth other than the predetermined tooth in the first phase) are alternately connected in series between the input point and the neutral point of the same phase. The first layer constituting the second phase winding 6V (specifically, the first layer wound around a predetermined tooth from among a plurality of teeth that are different from each other in the second phase) and the second layer constituting the second phase winding 6V (specifically, the second layer wound around a tooth other than the predetermined tooth in the second phase) are alternately connected in series between the input point and the neutral point of the same phase. The first layer of the third-phase winding 6W (specifically, the first layer wound around a predetermined tooth from among several teeth that are different from each other in the third phase) and the second layer of the third-phase winding 6W (specifically, the second layer wound around a tooth different from the predetermined tooth in the third phase) are alternately connected in series between the input point and the neutral point of the same phase. In the relationship between different phase windings, different layers are alternately connected in series via independent neutral points (specifically, in the order of first layer, second layer, first layer, second layer).

[0124] In the example shown in Figure 14, the three phase windings 6U, 6V, and 6W constitute a three-phase AC circuit in the case of two parallel, two-turn windings, but other numbers of parallel circuits may be used. It is sufficient that the first and second layers wound on different teeth within the same phase are connected in series to form a parallel circuit. The number of parallel circuits connected in series as described above may be an integer multiple of the number of divisions in the coil section (for example, 2n or 3n).

[0125] The number of turns in the winding in the first layer and the number of turns in the winding in the second layer may be the same. Also, the wire diameters of the strands that make up the coil portion wound around each tooth may be the same.

[0126] Note that while Figure 14 shows two parallel circuits as an example, this method is applicable to three or more parallel circuits. The effect of suppressing circulating current increases as the number of parallel circuits increases.

[0127] In the example shown in Figure 15, an example of a winding diagram for a three-phase AC circuit with two parallel, double-wound windings is shown, divided into U-phase, V-phase, and W-phase. In Figure 15, the stator 3 is unfolded linearly so that its circumferential direction extends in the left-right direction, and the teeth 42 of the stator 3, the three connecting grooves 52 of the insulator 5, etc. are schematically shown. An example of a winding diagram for the winding 6 is also shown, divided into three parts: U-phase, V-phase, and W-phase. Furthermore, because it is two parallel, double-wound, the winding 6 for each phase is divided into two parts in the circumferential direction of the stator 3.

[0128] Each of the multiple windings 6 has multiple coil sections 61, at least one jumper section 62, and two lead-out sections 63. In the same winding 6, each of the multiple coil sections 61 is wound around the teeth 42 by concentrated winding. In Figure 15, the coil sections 61 are shown surrounding the teeth 42 from below, but in reality, they are wound around the teeth 42 by concentrated winding.

[0129] The jumper wires 62 connect adjacent coil sections 61 in multiple coil sections 61 (in the example shown in Figure 15, the coil sections 61 of the U-phase winding 6U (first-phase winding), the coil sections 61 of the V-phase winding 6V (second-phase winding), and the coil sections 6W (third-phase winding)). The number of jumper wires 62 is one less than the number of coil sections 61. The two lead wires 63 form the ends of the same winding 6. The two lead wires 63 extend from the coil section 61.

[0130] In the stator 3, the coil sections 61 of the U-phase winding 6U, the V-phase winding 6V, and the W-phase winding 6W are arranged in a repeating sequence in the circumferential direction. Therefore, the coil sections 61 of windings 6 of the same phase are wound around teeth 42, which are arranged every three teeth. The example in Figure 15 shows the case where there are 12 slots. In the example in Figure 15, in each parallel circuit of each phase, a single turn (first layer) is shown as a solid line winding, and a double turn (second layer) is shown as a dashed line winding.

[0131] In the example shown in Figure 15, in each parallel U-phase circuit, the two coil sections 61 (solid and dashed windings) of the U-phase winding 6U, which is wound around the first division (the first of two divisions), are wound around the first and fourth teeth 42 (42-1, 42-4). In each parallel U-phase circuit, the two coil sections 61 (solid and dashed windings) of the U-phase winding 6U, which is wound around the second division (the second of two divisions), are wound around the seventh and tenth teeth 42 (42-7, 42-10). In each parallel V-phase circuit, the two coil sections 61 (solid and dashed windings) of the V-phase winding 6V, which is wound around the first division, are wound around the second and fifth teeth 42 (42-2, 42-5). In each parallel V-phase circuit, the two coil sections 61 (solid and dashed windings) of the V-phase winding 6V, which is wound in the second division, are wound around the 8th and 11th teeth 42 (42-8, 42-11). In each parallel W-phase circuit, the two coil sections 61 (solid and dashed windings) of the W-phase winding 6W, which is wound in the first division, are wound around the 3rd and 6th teeth 42 (42-3, 42-6). In each parallel W-phase circuit, the two coil sections 61 (solid and dashed windings) of the W-phase winding 6W, which is wound in the second division, are wound around the 9th and 12th teeth 42 (42-9, 42-12). In the example in Figure 15, the U-phase coil section 61U, the V-phase coil section 61V, and the W-phase coil section 61W are arranged in a repeating order to the right (first rotation direction RD1). Therefore, the numbers on teeth 42, as mentioned above, are arranged sequentially from left to right.

[0132] Furthermore, the jumper wire portion 62 of the U-phase winding 6U is housed in the U-phase jumper groove 52U. Similarly, the jumper wire portion 62 of the V-phase winding 6V is housed in the V-phase jumper groove 52V. The jumper wire portion 62 of the W-phase winding 6W is housed in the W-phase jumper groove 52W.

[0133] In the stator 3 illustrated in Figure 15, in each parallel circuit of each phase, the second end of each winding 6 wound in the first division, which is located opposite the first end that forms the input points U1 (U1-(1) shown as a solid line, U1-(2) shown as a dashed line), V1 (V1-(1) shown as a solid line, V1-(2) shown as a dashed line), and W1 (W1-(1) shown as a solid line, W1-(2) shown as a dashed line), is the output point Un1 (Un1-(1) shown as a solid line, Un1-(2) shown as a dashed line), Vn1 (Vn1-(1) shown as a solid line, Vn1-(2) shown as a dashed line), and Wn1 (Wn1-(1) shown as a solid line, Wn1-(2) shown as a dashed line). In each parallel circuit of each phase, the second end of each winding 6 that is wound around the second division, opposite to the first end which forms the input points U2 (U2-(1) shown as a solid line, U2-(2) shown as a dashed line), V2 (V2-(1) shown as a solid line, V2-(2) shown as a dashed line), and W2 (W2-(1) shown as a solid line, W2-(2) shown as a dashed line), is the output point Un2 (Un2-(1) shown as a solid line, Un2-(2) shown as a dashed line), Vn2 (Vn2-(1) shown as a solid line, Vn2-(2) shown as a dashed line), and Wn2 (Wn2-(1) shown as a solid line, Wn2-(2) shown as a dashed line).

[0134] The three-phase output points Un2 (shown as a dashed line, Un2-(2)), Vn1 (shown as a solid line, Vn1-(1)), and Wn1 (shown as a solid line, Wn1-(1)) constitute the neutral point N1 of the connection shown in Figure 14. The three-phase output points Un1 (shown as a dashed line, Un1-(2)), Vn2 (shown as a solid line, Vn2-(1)), and Wn1 (shown as a solid line, Wn2-(1)) constitute the neutral point N2 of the connection shown in Figure 14.

[0135] In the example shown in Figure 15, in the winding that wraps the coil around multiple teeth of each phase, a parallel circuit is formed by alternately connecting a first layer and a second layer, which are divided into two parts, in series within the same phase.

[0136] Specifically, the output point of the first layer of the first division of the U-phase (shown by a solid line, Un1-(1)) is connected to the input point of the second layer of the second division of the U-phase (shown by a dashed line, U2-(2)). Also, the output point of the second layer of the first division of the U-phase (shown by a dashed line, Un1-(2)) is connected to the input point of the first layer of the second division of the U-phase (shown by a solid line, U2-(1)). The output point of the first layer of the first division of the V-phase (shown by a solid line, Vn1-(1)) is connected to the input point of the second layer of the second division of the V-phase (shown by a dashed line, V2-(2)). Also, the output point of the second layer of the first division of the V-phase (shown by a dashed line, Vn1-(2)) is connected to the input point of the first layer of the second division of the V-phase (shown by a solid line, V2-(1)). The output point of the first layer of the first division of the W phase (shown by a solid line, Wn1-(1)) is connected to the input point of the second layer of the second division of the W phase (shown by a dashed line, W2-(2)). Similarly, the output point of the second layer of the first division of the W phase (shown by a dashed line, Wn1-(2)) is connected to the input point of the first layer of the second division of the W phase (shown by a solid line, W2-(1)). With these connections within the same phase, even in the relationship between different phase windings, different layers are alternately connected in series via independent neutral points.

[0137] In the example shown in Figure 15, the winding, which wraps the coil section around multiple teeth, is configured such that the output point of the first layer, which is divided into two sections, is connected to the input point of the second layer. With this configuration, since the coil extends around the entire circumference, the generation of a potential difference due to rotor eccentricity, for example, is less likely to occur.

[0138] Furthermore, the number of turns of one layer wrapped around a predetermined tooth and the number of turns of a layer wrapped around another tooth and different from the first layer may be the same. Also, the one layer wrapped around a predetermined tooth may be divided at the point where it is half-wound around the predetermined tooth, and the layer wrapped around another tooth and different from the first layer may be divided at the point where it is half-wound around the other tooth.

[0139] <Explanation of Circulating Current> In a two-parallel circuit with a double-wound wire, circulating current may occur between phases. Let Ra1 and Ra2 be the phase resistances of the first phase (e.g., U phase) with one turn (first layer) and the second phase (second layer), respectively. Let Rb1 and Rb2 be the phase resistances of the second phase (e.g., V phase) with one turn (first layer) and the second phase (second layer), respectively. Since the average circumference of the multi-strand wires wound around the teeth 42 differs between the one-turn (first layer) and the double-turn (second layer), this is shown by the following equations (4-1) and (4-2). (Equation (4-1)) Ra1 ≠ Ra2 (Equation (4-2)) Rb1 ≠ Rb2

[0140] On the other hand, when the phases are different, the phase resistances may be approximately the same, as shown in the following equations (4-3) and (4-4). (Equation (4-3)) Ra1 ≈ Rb1 (Equation (4-4)) Ra2 ≈ Rb2

[0141] Since the inter-line resistance Rab (for example, the resistance of the UV phase) is equal to the number of parallel circuits, when the inter-line resistance of one parallel circuit is Rab1 and the inter-line resistance of the other is Rab2, it is given by the following equations (4-5) and (4-6): (Equation (4-5)) Rab1 = Ra1 + Ra2 + Rb1 + Rb2 (Equation (4-6)) Rab2 = Ra1 + Ra2 + Rb1 + Rb2

[0142] By connecting different layers wound on different teeth alternately in series between the input point and neutral point of the same phase, so that the resistance within the same phase is the same, the generation of interphase circulating current can be suppressed.

[0143] From equations (4-5) and (4-6) above, we obtain the following equation (4-7): (Equation (4-7)) Rab1 = Rab2

[0144] When equation (4-7) above is satisfied, the resistance between the two lines becomes the same, and thus the generation of circulating current between the lines can be suppressed.

[0145] As described above, in this embodiment, the multiple windings 6 include multiple phase windings 6U, 6V, and 6W that are in different phases from each other. Of the multiple phase windings 6U, 6V, and 6W, one of the first layer 61L1 and second layer 61L2 that constitute one of the phase windings is wound around a predetermined tooth, and the other layer of the first layer 61L1 and second layer 61L2 that constitute the same phase winding as the aforementioned one is wound around a tooth other than the predetermined tooth and is different from the other layer, and these are alternately connected in series between the input point and the neutral point of the same phase. For example, when multiple phase windings that are in different phases are connected, if the neutral point of the first layer and the second layer of each parallel circuit is made common, a circulating current may be generated between the phases because the resistance values ​​of the first layer and the second layer are different. In contrast, with this configuration, when connecting multiple phase windings 6U, 6V, and 6W that are in different phases, the layers that are wound on different teeth within the same phase, constituting the same phase winding, are alternately connected in series between the input point and the neutral point of the same phase. This reduces the resistance difference (potential difference) within the same phase, making it difficult for circulating current to flow. Furthermore, because the layers wound on different teeth within the same phase are alternately connected in series and in a parallel circuit, the resistance difference between lines passing through the same phase or the neutral point is reduced. Therefore, the generation of circulating current not only between phases but also between lines can be suppressed. Consequently, efficiency degradation can be suppressed more effectively.

[0146] In this embodiment, the number of turns of one layer wound around a predetermined tooth and the number of turns of a layer wound around another tooth that is different from the first layer may be the same. With this configuration, compared to the case where the number of turns of one layer wound around a predetermined tooth and the number of turns of a layer wound around another tooth that is different from the first layer are different, it is easier to make the resistance within the same phase uniform, and thus it is possible to make it difficult for circulating current to flow. Therefore, a decrease in efficiency can be suppressed.

[0147] In this embodiment, one layer wound around a predetermined tooth may be divided at a point where it is half wound around the predetermined tooth, and another layer wound around a different tooth and different from the first layer may also be divided at a point where it is half wound around the other tooth. This configuration makes it easier to make the resistance within the same phase as uniform as possible, thus making it difficult for circulating current to flow. Therefore, efficiency degradation can be suppressed.

[0148] In this embodiment, an example was given in which each of the multiple coil sections has a laminated structure having a first layer and a second layer, but the invention is not limited to this. For example, each coil section may have a laminated structure further having a third layer arranged on the outer circumference of the second layer. For example, one of the first, second, and third layers that constitute one of the multiple phase windings and are wound around a predetermined tooth, and one of the first, second, and third layers that constitute the same phase winding as the one mentioned above and are wound around a tooth other than the predetermined tooth and are different from the one mentioned above, may be alternately connected in series between the input point and the neutral point of the same phase. With this configuration, even in the case of a laminated structure having a first layer, a second layer, and a third layer, when connecting multiple phase windings that are in different phases, different layers that are wound around different teeth within the same phase and that constitute the same phase winding are alternately connected in series between the input point and the neutral point of the same phase. This reduces the resistance difference (potential difference) within the same phase, making it difficult for circulating current to flow. Furthermore, because layers wound on different teeth within the same phase are alternately connected in series and in a parallel circuit, the connection is made such that the resistance difference between lines passing through the same phase or neutral point is reduced. Therefore, the generation of circulating current can be suppressed not only between phases but also between lines. Consequently, efficiency degradation can be suppressed more effectively.

[0149] <Fifth Embodiment> Figure 16 is a circuit diagram showing an example of a three-phase AC circuit in the stator according to the fifth embodiment, where there are two parallel, two-turn windings. In Figure 16, the one-turn (first layer) and two-turn (second layer) windings of each phase are indicated by (1) and (2), respectively. The stator according to the fifth embodiment will be described below with reference to Figure 16. In the configuration shown in Figure 16, the same reference numerals are used for components as in the embodiments described above, and their detailed descriptions are omitted.

[0150] The three-phase AC circuit shown in Figure 16 is composed of four star connections. In the example shown in Figure 16, when connecting phase windings 6U, 6V, and 6W that are in different phases, one of the first layer 61L1 and the second layer 61L2 (either the first layer (1) or the second layer (2)) that constitutes one of the phase windings 6U, 6V, and 6W is connected to the other of the first layer 61L1 and the second layer 61L2 that constitute a phase winding different from the aforementioned phase winding, via neutral points N1, N2, N3, and N4. In the example shown in Figure 16, when the number of parallel windings 6 is p and the number of neutral points is N, the condition N = 2p is satisfied.

[0151] In this embodiment, the first layer 61L1 constituting the first phase winding 6U, the second layer 61L2 constituting the second phase winding 6V, and the second layer 61L2 constituting the third phase winding 6W are connected to each other via a first neutral point. The second layer 61L2 constituting the first phase winding 6U, the first layer 61L1 constituting the second phase winding 6V, and the first layer 61L1 constituting the third phase winding 6W are connected to each other via a second neutral point different from the first neutral point.

[0152] In the example shown in Figure 16, the first of the six star connections is formed by connecting the first layer (1) that constitutes the first phase winding 6U, the second layer (2) that constitutes the second phase winding 6V, and the second layer (2) that constitutes the third phase winding 6W at a neutral point N1 (first neutral point). The second of the six star connections is formed by connecting the second layer (2) that constitutes the first phase winding 6U, the first layer (1) that constitutes the second phase winding 6V, and the first layer (1) that constitutes the third phase winding 6W at a neutral point N2 (second neutral point). The third of the six star connections is formed by connecting the first layer (1) that constitutes the first phase winding 6U, the second layer (2) that constitutes the second phase winding 6V, and the second layer (2) that constitutes the third phase winding 6W at a neutral point N3. The fourth of the six, the star connection, is constructed by connecting the second layer (2) that constitutes the first phase winding 6U, the first layer (1) that constitutes the second phase winding 6V, and the first layer (1) that constitutes the third phase winding 6W at the neutral point N4.

[0153] Note that while Figure 16 shows two parallel circuits as an example, this method is applicable to three or more parallel circuits. The effect of suppressing circulating current increases as the number of parallel circuits increases.

[0154] <Explanation of Inter-Line Resistance> The resistance between windings of two phases that are in different phases is called "inter-line resistance," and the resistance between windings within the same phase is called "phase resistance." Let Rab1 be the inter-line resistance of a single turn (first layer), and Rab2 be the inter-line resistance of a double turn (second layer). Let Ra1 and Ra2 be the phase resistances of the first phase (e.g., U phase) for a single turn (first layer) and the double turn (second layer), respectively. Let Rb1 and Rb2 be the phase resistances of the second phase (e.g., V phase) for a single turn (first layer) and the double turn (second layer), respectively. Then, the following equations (5-1) and (5-2) are given. (Equation (5-1)) Rab1 = Ra1 + Rb1 (Equation (5-2)) Rab2 = Ra2 + Rb2

[0155] Since the average circumference of the 60M multi-strand wire wound around the teeth 42 differs between a single winding (first layer) and a double winding (second layer), the following equations (5-3) and (5-4) are obtained. (Equation (5-3)) Ra1 ≠ Ra2 (Equation (5-4)) Rb1 ≠ Rb2

[0156] From equations (5-1) to (5-4) above, we obtain the following equation (5-5): Rab1 ≠ Rab2

[0157] On the other hand, when the phases are different, the phase resistances may be approximately the same, as shown in the following equations (5-6) and (5-7). (Equation (5-6)) Ra1 ≈ Ra2 (Equation (5-7)) Rb1 ≈ Rb2

[0158] If equations (5-6) and (5-7) above are satisfied, connect them so that equations (5-8) and (5-9) below are also satisfied. (Equation (5-8)) Rab1 = Ra1 + Rb2 (Equation (5-9)) Rab2 = Ra2 + Rb1

[0159] By satisfying equations (5-8) and (5-9) above, we obtain the following equation (5-10): (Equation (5-10)) Rab1 ≈ Rab2

[0160] As described above, in this embodiment, the multiple windings 6 include multiple phase windings 6U, 6V, and 6W that are in different phases from each other. Either one of the first layer portion 61L1 and the second layer portion 61L2 that constitute one of the multiple phase windings 6U, 6V, and 6W is connected to the other of the first layer portion 61L1 and the second layer portion 61L2 that constitute a phase winding different from the aforementioned phase winding, via a neutral point. With this configuration, when connecting multiple phase windings 6U, 6V, and 6W that are in different phases from each other, either one of the first layer portion 61L1 and the second layer portion 61L2 that constitute the different phase windings 6U, 6V, and 6W is connected to the other via a neutral point where the potential is approximately constant. Furthermore, since the first layer portion 61L1 and the second layer portion 61L2 are alternately connected via different phases, the difference due to the winding method is canceled out, and the resistance difference (potential difference) can be suppressed as much as possible. Therefore, the decrease in efficiency can be suppressed.

[0161] In this embodiment, the multiple phase windings 6U, 6V, and 6W include a first phase winding 6U, a second phase winding 6V, and a third phase winding 6W, which are in different phases from each other. The first layer 61L1 constituting the first phase winding 6U, the second layer 61L2 constituting the second phase winding 6V, and the second layer 61L2 constituting the third phase winding 6W are connected to each other via a first neutral point. The second layer 61L2 constituting the first phase winding 6U, the first layer 61L1 constituting the second phase winding 6V, and the first layer 61L1 constituting the third phase winding 6W are connected to each other via a second neutral point different from the first neutral point. With this configuration, in the connection of the three phase windings 6U, 6V, and 6W, the different layers 61L1 and 61L2 are connected to each other via independent neutral points, so that the resistance difference (potential difference) can be suppressed as much as possible. Therefore, the decrease in efficiency can be suppressed.

[0162] In this embodiment, when the number of parallel windings 6 is p and the number of neutral points is N, the condition N = 2p is satisfied. With this configuration, independent neutral points can be set while taking into account the number of parallel windings 6, so the resistance difference (potential difference) can be kept to a minimum. Therefore, the decrease in efficiency can be suppressed.

[0163] As described above, there is a difference in resistance between single-turn (first layer) and double-turn (second layer) windings because the average circumference within the slot is different. According to this embodiment, by connecting single-turn (first layer) and double-turn (second layer) windings alternately via a neutral point in different phases, the inter-wire resistance becomes approximately the same, and the potential difference is minimized (when there is almost no difference in circumference or resistance). In this way, it can be applied whether the number of strands in the single-turn (first layer) and double-turn (second layer) windings is the same or different. Therefore, whether the total number of strands is even or odd, a more efficient motor can be realized by suppressing circulating current while achieving a high packing factor.

[0164] <Sixth Embodiment> Figure 17 is a circuit diagram showing an example of a three-phase AC circuit in the stator 3 according to the sixth embodiment, where there are two parallel, two-turn windings. In Figure 17, the one-turn (first layer) and two-turn (second layer) windings of each phase are indicated by (1) and (2), respectively. Figure 18 is a diagram showing an example of the relationship between the wire diameter and number of strands of wires constituting the multi-strand wire in each layer of the stator according to the sixth embodiment. The stator according to the sixth embodiment will be described below with reference to Figures 17 and 18. In the configuration shown in Figure 17, the same reference numerals are used for components similar to those in the embodiments described above, and their detailed descriptions are omitted.

[0165] In the example shown in Figure 17, the three phase windings 6U, 6V, and 6W constitute a three-phase AC circuit in the case of three parallel, two-turn windings. The three-phase AC circuit shown in Figure 17 is composed of four star connections. In the example shown in Figure 17, when connecting phase windings 6U, 6V, and 6W that are of different phases, the same layers that make up each phase winding 6U, 6V, and 6W (either the first layer (1) or the second layer (2)) are connected to each other via different neutral points N1, N2, N3, and N4. In the example shown in Figure 17, when the number of parallel windings 6 is p and the number of neutral points is N, the condition N = 2p is satisfied.

[0166] The first of the six star connections is constructed by connecting the first layers (1) of the three phase windings 6U, 6V, and 6W at the neutral point N1. The second of the six star connections is constructed by connecting the second layers (2) of the three phase windings 6U, 6V, and 6W at the neutral point N2. The third of the six star connections is constructed by connecting the first layers (1) of the three phase windings 6U, 6V, and 6W at the neutral point N3. The fourth of the six star connections is constructed by connecting the second layers (2) of the three phase windings 6U, 6V, and 6W at the neutral point N4.

[0167] In the example shown in Figure 17, two parallel circuits are used as an example, but this method can also be applied to three or more parallel circuits. The effect of suppressing circulating current increases as the number of parallel circuits increases.

[0168] <Explanation of the Conditional Formula> In the stator 3 of this embodiment, when the average circumference and total cross-sectional area of ​​the multi-strand wires 60M in the first layer 61L1 are L1 and S1, respectively, and the average circumference and total cross-sectional area of ​​the multi-strand wires 60M in the second layer 61L2 are L2 and S2, respectively, the following conditional formula (6-1) is satisfied. (Conditional Formula (6-1)) L1 / L2 = S1 / S2

[0169] The factors that cause a potential difference (resistance difference) include (1) the difference in the average circumference of the wire wound within the slot, and (2) the difference in the average circumference of the connecting wire section. Since factor (1) is dominant, the average circumference of the connecting wire section has been omitted.

[0170] For example, in the case of 36 slots, n is 4, which corresponds to 4 series slots. Note that the number of series connections in L1 and L2 is the same, so when considering the ratio of L1 to L2, the number of series connections n cancels out. When the resistance values ​​for n series slots in the first layer 61L1 and the resistance values ​​for n series slots in the second layer 61L2 are Rn1 and Rn2, respectively, and the resistivity is ρ, the following equations (6-2) and (6-3) hold. (Equation (6-2)) Rn1 = ρL1 / S1 (Equation (6-3)) Rn2 = ρL2 / S2

[0171] In order for Rn1 ≈ Rn2, it is necessary to satisfy L1 / S1 = L2 / S2, which leads to the above condition (6-1).

[0172] In the stator 3 of this embodiment, when the wire diameter and number of strands of the individual wires 60W constituting the multi-strand wire 60M in the first layer 61L1 are set to D1 and x1, respectively, and the wire diameter and number of strands of the individual wires 60W constituting the multi-strand wire 60M in the second layer 61L2 are set to D2 and x2, respectively, the following conditional equation (6-4) is satisfied. (Conditional equation (6-4)) S1 / S2∝D1 ２ ×x1 / (D2 ２ ×x2)

[0173] From the above condition (6-4), the following two conditions (6-5) and (6-6) are obtained. (Condition (6-5)) When D1 ≥ D2, if L1 < L2, then x1 < x2 (Condition (6-6)) When D1 < D2, if L1 < L2, then x1 > x2

[0174] The relationship between D1 and D2 is expressed by the following equation (6-7): (Equation (6-7)) D2 = D1 × √(x1 × L2 / (x2 × L1))

[0175] <Relationship between wire diameter and number of strands of wires constituting the multi-strand wire 60 in each layer> Figure 18 is a diagram showing an example of the relationship between wire diameter and number of strands of wires 60W constituting the multi-strand wire 60M in each layer 61L1, 61L2 of the stator 3 according to the embodiment. In Figure 18, <Normative 1> shows an example <Example 1> of the difference in the number of strands (x2-x1), the number of strands (x1, x2), and wire diameter (D1, D2) when the above condition (6-5) is satisfied. On the other hand, <Normative 2> shows an example <Example 2> of the difference in the number of strands (x2-x1), the number of strands (x1, x2), and wire diameter (D1, D2) when the above condition (6-6) is satisfied.

[0176] <Effects> As described above, in this embodiment, when the average circumference and total cross-sectional area of ​​the multi-strand wire 60M in the first layer 61L1 are L1 and S1, respectively, and the average circumference and total cross-sectional area of ​​the multi-strand wire 60M in the second layer 61L2 are L2 and S2, respectively, the condition L1 / L2 = S1 / S2 is satisfied. With this configuration, the resistance difference between the first layer 61L1 and the second layer 61L2 can be reduced, making it difficult for circulating current to flow. Therefore, a decrease in efficiency can be suppressed.

[0177] In this embodiment, each of the multiple strands 60W is made of a round wire. When the wire diameter and number of strands of the strands 60W constituting the multi-strand wire 60M in the first layer 61L1 are D1 and x1, respectively, and the wire diameter and number of strands of the strands 60W constituting the multi-strand wire 60M in the second layer 61L2 are D2 and x2, respectively, then S1 / S2∝D1 ２ ×x1 / (D2 ２ The condition of ×x² is satisfied. With this configuration, considering the wire diameter and number of strands of the 60W wires constituting the multi-strand wire 60M, the resistance difference between the first layer 61L1 and the second layer 61L2 can be reduced, making it difficult for circulating current to flow. Therefore, efficiency degradation can be suppressed.

[0178] In this embodiment, when D1 ≥ D2, the condition x1 < x2 is satisfied if L1 < L2. With this configuration, in a multi-strand winding, if the wire diameter of the strands 60W in the first layer 61L1 is made larger than or equal to the wire diameter of the strands 60W in the second layer 61L2, and the average circumference of the multi-strand wires 60M in the first layer 61L1 is made shorter than the average circumference of the multi-strand wires 60M in the second layer 61L2, the resistance difference between the first layer 61L1 and the second layer 61L2 can be reduced, making it difficult for circulating current to flow. Therefore, a decrease in efficiency can be suppressed.

[0179] In this embodiment, when D1 < D2, the condition x1 > x2 is satisfied if L1 < L2. With this configuration, in a multi-winding system, if the wire diameter of the strands 60W in the first layer 61L1 is made smaller than the wire diameter of the strands 60W in the second layer 61L2, and the average circumference of the multi-winding wires 60M in the first layer 61L1 is made shorter than the average circumference of the multi-winding wires 60M in the second layer 61L2, the resistance difference between the first layer 61L1 and the second layer 61L2 can be reduced, making it difficult for circulating current to flow. Therefore, efficiency degradation can be suppressed.

[0180] <Modified Examples> In the above embodiment, the average circumference and total cross-sectional area of ​​the multi-wires in the first layer were set to L1 and S1, respectively, and the average circumference and total cross-sectional area of ​​the multi-wires in the second layer were set to L2 and S2, respectively. An example was given where the condition L1 / L2 = S1 / S2 was satisfied, but the embodiment is not limited to this. For example, the condition L1 / L2 = S1 / S2 does not need to be satisfied. The relationship between the average circumference and total cross-sectional area of ​​the multi-wires in each layer can be changed according to the design specifications.

[0181] In the above embodiment, each of the multiple strands is made of a round wire, and when the wire diameter and number of strands of the strands constituting the multi-strand wire in the first layer are D1 and x1, respectively, and the wire diameter and number of strands of the strands constituting the multi-strand wire in the second layer are D2 and x2, respectively, then S1 / S2∝D1 ２ ×x1 / (D2 ２ The explanation provided an example that satisfies the condition ×x², but it is not limited to this. For example, each of the multiple strands may be composed of a square wire. For example, S1 / S2∝D1 ２ ×x1 / (D2２ The condition of ×x² does not need to be met. The configuration of each strand, and the relationship between the wire diameter and number of strands constituting the multi-strand wire in each layer, can be changed according to the design specifications.

[0182] In the above embodiment, an example was given in which the condition x1 < x2 is satisfied when D1 ≥ D2 and L1 < L2, but it is not limited to this. For example, the condition x1 < x2 does not need to be satisfied. In a multi-strand winding, if the wire diameter of the strands in the first layer is made larger than or equal to the wire diameter of the strands in the second layer, and the average circumference of the multi-strand winding in the first layer is made shorter than the average circumference of the multi-strand winding in the second layer, the relationship between the number of strands constituting the multi-strand winding in each layer can be changed according to the design specifications.

[0183] In the above embodiment, an example was given in which the condition x1 > x2 is satisfied when D1 < D2 and L1 < L2, but it is not limited to this. For example, the condition x1 > x2 does not need to be satisfied. In a multi-strand winding, if the wire diameter of the strands in the first layer is made smaller than the wire diameter of the strands in the second layer, and the average circumference of the multi-strand winding in the first layer is made shorter than the average circumference of the multi-strand winding in the second layer, the relationship between the number of strands constituting the multi-strand winding in each layer can be changed according to the design specifications.

[0184] In the above embodiment, an example was given in which the number of turns of the winding in the first layer and the number of turns of the winding in the second layer are the same, but this is not limited to this. For example, the number of turns of the winding in the first layer and the number of turns of the winding in the second layer may be different. The number of turns of the winding in each layer can be changed according to the design specifications.

[0185] In the above embodiment, the multiple windings include multiple phase windings with different phases, and the example described shows that one of the first and second layers constituting one of the multiple phase windings is connected to the other of the first and second layers constituting a phase winding different from the aforementioned phase winding via a neutral point, but the invention is not limited to this. For example, in the connection of multiple phase windings that are different from each other, the same layers constituting each phase winding (first layers to each other or second layers to each other) may be connected to each other via a neutral point. The connection method between the first phase winding and the second phase winding can be changed according to the design specifications.

[0186] In the above embodiment, the multiple phase windings include a first phase winding, a second phase winding, and a third phase winding, each in a different phase. The first layer constituting the first phase winding, the second layer constituting the second phase winding, and the second layer constituting the third phase winding are connected to each other via a first neutral point, and the second layer constituting the first phase winding, the first layer constituting the second phase winding, and the first layer constituting the third phase winding are connected to each other via a second neutral point different from the first neutral point. However, the embodiment is not limited to this example. For example, in the connection of three phase windings, different layers may be connected to each other via the same neutral point. The connection configuration of the three phase windings can be changed according to the design specifications.

[0187] In the above embodiment, an example was given where the condition N = 2p is satisfied, where p is the number of windings in parallel and N is the number of neutral points, but the invention is not limited to this example. For example, the condition N = 2p does not need to be satisfied. The relationship between the number of windings in parallel and the number of neutral points can be changed according to the design specifications.

[0188] In the above embodiment, an example was given in which each of the multiple coil sections has a laminated structure having a first layer and a second layer, but the invention is not limited to this. For example, each coil section may have a laminated structure further having a third layer arranged on the outer circumference of the second layer. For example, each coil section may be composed of one turn (first layer), two turns (second layer), and three turns (third layer). That is, each coil section may have three or more turns of winding. The laminated structure of each coil section can be changed according to the design specifications.

[0189] Although one embodiment has been described above with reference to the drawings, the specific configuration is not limited to that described above. Additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the spirit of this disclosure, and the above-described embodiments can be combined as appropriate.

[0190] 1...Motor, 2...Rotor, 3...Stator, 4...Stator core, 6...Winding, 6U...U-phase winding (first phase winding), 6V...V-phase winding (second phase winding), 6W...W-phase winding (third phase winding), 42...Teeth, 43...Slot, 60W...Straight wire, 60M...Multi-strand wire, 61...Coil section, 61L1...First layer section, 61L2...Second layer section, 61L3...Third layer section, 62...Jumper wire section, 63...Leader wire section, PD...Protruding direction, N1...First neutral point (neutral point), N2...Second neutral point (neutral point), N3...Third neutral point (neutral point)

Claims

1. A stator comprising: an annular stator core having a plurality of slots arranged in the circumferential direction and a plurality of teeth formed between adjacent slots and protruding radially; and a plurality of windings wound around the plurality of teeth, each of which is a multi-strand wire made of a bundle of a plurality of strands, arranged in parallel to each other, and having a plurality of coil portions wound around the teeth by concentrated winding, each of which has a first layer portion arranged along the outer circumference of the teeth from one end to the other in the protruding direction of the teeth, and a second layer portion arranged on the outer circumference side of the first layer portion.

2. The stator according to claim 1, wherein each of the plurality of coil portions further has a third layer portion disposed on the outer periphery of the second layer portion.

3. The stator according to claim 1, wherein the number of strands constituting the multi-strand wire in the first layer is less than the number of strands constituting the multi-strand wire in the second layer.

4. The stator according to claim 1, wherein each of the plurality of strands is made of a round wire, and the wire diameter of the strands constituting the multi-strand wire in the first layer is smaller than the wire diameter of the strands constituting the multi-strand wire in the second layer.

5. The stator according to claim 1, wherein when the average circumference and total cross-sectional area of ​​the multi-stripe wires in the first layer are L1 and S1, respectively, and the average circumference and total cross-sectional area of ​​the multi-stripe wires in the second layer are L2 and S2, respectively, the condition L1 / L2 = S1 / S2 is satisfied.

6. Each of the multiple strands is made of a round wire, and when the wire diameter and number of strands of the strands constituting the multi-strand wire in the first layer are D1 and x1, respectively, and the wire diameter and number of strands of the strands constituting the multi-strand wire in the second layer are D2 and x2, respectively, then S1 / S2∝D1 ２ ×x1 / (D2 ２ The stator according to claim 5, satisfying the condition of ×x².

7. The stator according to claim 1, wherein the number of turns of the winding in the first layer and the number of turns of the winding in the second layer are the same.

8. The stator according to claim 1, wherein the plurality of windings include a plurality of phase windings with different phases from each other, and one of the first layer and the second layer constituting one of the plurality of phase windings is connected to the other of the first layer and the second layer constituting a phase winding different from the one phase winding via a neutral point.

9. The stator according to claim 8, wherein the plurality of windings include a first phase winding, a second phase winding, and a third phase winding having different phases from each other, the first layer constituting the first phase winding, the second layer constituting the second phase winding, and the second layer constituting the third phase winding are connected to each other via a first neutral point, and the second layer constituting the first phase winding, the first layer constituting the second phase winding, and the first layer constituting the third phase winding are connected to each other via a second neutral point different from the first neutral point.

10. The stator according to claim 8, wherein the condition N = 2p is satisfied when the number of parallel windings is p and the number of neutral points is N.

11. The stator according to claim 1, wherein the plurality of windings include a plurality of phase windings with different phases from each other, and either one of the first layer and the second layer constituting one of the plurality of phase windings is connected in parallel to the first layer and the second layer constituting the same phase winding as the one of the phase windings.

12. The stator according to claim 2, wherein the plurality of windings include a plurality of phase windings with different phases, and at least one of the first layer, second layer, and third layer that constitute one of the plurality of phase windings is connected in parallel to the layer that constitutes the same phase winding as the one phase winding as the first layer, second layer, and third layer that constitutes the same phase winding as the one phase winding.

13. The stator according to claim 12, wherein the plurality of phase windings include a first phase winding, a second phase winding, and a third phase winding, each having different phases from the others, the first layer constituting the first phase winding, the third layer constituting the second phase winding, and the third layer constituting the third phase winding are connected to each other via a first neutral point, the second layer constituting the first phase winding, the second layer constituting the second phase winding, and the second layer constituting the third phase winding are connected to each other via a second neutral point different from the first neutral point, and the third layer constituting the first phase winding, the first layer constituting the second phase winding, and the first layer constituting the third phase winding are connected to each other via a third neutral point different from the first and second neutral points.

14. The stator according to claim 1, wherein the plurality of windings include a plurality of phase windings that are in different phases from each other, and one of the first and second layers constituting one of the plurality of phase windings is wound around a predetermined tooth, and the first and second layers constituting the same phase winding as the one phase winding is wound around a tooth other than the predetermined tooth and is different from the one layer, and these layers are alternately connected in series between the input point and the neutral point of the same phase.

15. The stator according to claim 14, wherein the number of turns of one layer wound around the predetermined teeth and the number of turns of a layer wound around the other teeth and different from the one layer are the same.

16. The stator according to claim 14, wherein one layer wrapped around a predetermined tooth is divided at a point where it is half-wound around the predetermined tooth, and another layer wrapped around a different tooth and different from the first layer is divided at a point where it is half-wound around the other tooth.

17. The stator according to claim 2, wherein the plurality of windings include a plurality of phase windings that are in different phases from each other, and one of the first, second, and third layers that constitute one of the plurality of phase windings is wound around a predetermined tooth, and one of the first, second, and third layers that constitute the same phase winding as the one phase winding is wound around a tooth other than the predetermined tooth and is different from the one layer, and these layers are alternately connected in series between the input point and the neutral point of the same phase.

18. A motor comprising a rotor and a stator according to any one of claims 1 to 17.

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