Stator

Abstract

To avoid or suppress generation of a surge voltage in a stator of an electric motor.SOLUTION: A stator includes: a cylindrical stator core extending in an axial direction between a first end surface and a second end surface; a plurality of slots provided on an inner peripheral surface of the stator core; and a plurality of coils distributed and wound around the plurality of slots. The number n of slots satisfies a relationship of n=6p when P is the number of magnetic poles of a rotor. In each slot, coil segments are arranged so as to constitute a plurality of layers along a radial direction. In each coil, a start point and an end point are provided on a first end surface side of the stator core. In addition, in the outermost layer and the innermost layer in the slot in the radial direction, two coil segments located in the same layer are connected to each other. A section displaced in the radial direction between the outermost layer and the innermost layer has an oblique wave winding section in which a direction displaced in a circumferential direction and the radial direction on the first end surface side and a direction displaced in the circumferential direction and the radial direction on a second end surface side continuously coincide with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a stator for an electric motor. [Background technology]

[0002] Patent Document 1 describes a stator for an electric motor. This stator includes a stator core, a plurality of slots provided in the stator core, and a plurality of stator coils (also simply referred to as coils) each composed of a plurality of coil segments. The coils are wound in a distributed manner with irregular slot pitches (intervals) relative to the plurality of slots. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-103038 Summary of the Invention [Problem to be solved by the invention]

[0004] In the stator of an electric motor, it is necessary to suppress the occurrence of coil resonance. This is because coil resonance can, for example, generate excessive surge voltage. Coil resonance depends not only on the electrical characteristics (natural frequency) of the coil but also on the electrical characteristics (natural frequency) of the inverter connected to the coil. In other words, even if a stator does not exhibit significant resonance when combined with one inverter, it may still exhibit significant resonance when combined with another inverter. Therefore, for example, if the inverter design is changed and its electrical characteristics change, it is often necessary to change the stator design accordingly (i.e., adjust the coil's electrical characteristics).

[0005] One method for adjusting the electrical characteristics of a coil is to change the way the coil is wound around the stator core. Conventionally, two coil winding methods have been known: "lap winding" and "wave winding." The electrical characteristics of the coil are adjusted by changing from lap winding to wave winding, or vice versa. However, depending on the inverter that is combined, these two winding methods alone may not be able to sufficiently suppress coil resonance, even if they are changed between them.

[0006] In view of the above, the present specification provides a new and useful technique for winding coils in a stator. [Means for solving the problem]

[0007] The technology disclosed in this specification is embodied in a stator of a motor driven by electricity. The stator includes a cylindrical stator core extending axially between a first end face and a second end face, a plurality of slots disposed on the inner peripheral surface of the stator core, each arranged circumferentially and extending axially, and a plurality of coils wound in a distributed manner about the plurality of slots, each consisting of a plurality of coil segments. When the number of the slots is n and the number of magnetic poles of the rotor is P, the relationship n = 6p is satisfied. In each of the plurality of slots, the coil segments are arranged in multiple layers along the radial direction, each of the plurality of coils has a start point and an end point on the first end face side of the stator core. In the radially outermost and innermost layers of the slot, two coil segments located in the same layer are connected to each other. The radially displaced section between the outermost and innermost layers has a diagonal wave winding section in which the circumferential and radial displacement directions on the first end face side and the circumferential and radial displacement directions on the second end face side are continuously aligned.

[0008] In the above configuration, each coil has a diagonal wave winding section. The way the coil is wound in the diagonal wave winding section (hereinafter referred to as diagonal wave winding) differs from both conventional lap winding and wave winding. For example, in conventional lap winding, the coils are displaced in opposite directions in the circumferential direction on the first end face side and the second end face side of the stator core. That is, when the coil is displaced to one side in the circumferential direction on the first end face side, the coil is displaced to the other side in the circumferential direction on the second end face side. Therefore, in lap winding, the direction of circumferential displacement of the coil on the first end face side and the direction of circumferential displacement of the coil on the second end face side do not continuously coincide. In contrast, in the diagonal wave winding according to the present technology, the direction of circumferential displacement on the first end face side and the direction of circumferential displacement on the second end face side continuously coincide, which differs from lap winding in this respect.

[0009] On the other hand, in conventional wave winding, the coils are displaced in opposite radial directions on the first end face side and the second end face side of the stator core. That is, when the coils are displaced radially inward on the first end face side, they are displaced radially outward on the second end face side. Therefore, in wave winding, the direction of radial displacement of the coils on the first end face side and the direction of radial displacement of the coils on the second end face side do not continuously coincide. In contrast, in the stator according to the present technology, the direction of radial displacement of the coils on the first end face side of the stator core and the direction of radial displacement of the coils on the second end face side of the stator core continuously coincide, which is different from wave winding.

[0010] As described above, the oblique wave winding according to the present technology is a coil winding method that differs from both conventional lap winding and wave winding. Therefore, when changing the coil winding method for the purpose of suppressing coil resonance, this oblique wave winding can be added as a new option in addition to conventional lap winding and wave winding. This increases the degree of freedom when adjusting the electrical characteristics of the stator, making it possible to more effectively suppress coil resonance.

[0011] In one embodiment of the present technology, in each of the multiple coils, the section that displaces radially between the outermost layer and the innermost layer in the slot may further have a lap winding section in which the direction of circumferential displacement on the first end face side and the direction of circumferential displacement on the second end face side are reversed to each other.

[0012] In the above configuration, in addition to the diagonal wave winding section, each coil further has a lap winding section. With this configuration, it is possible to distribute the frequency band in which the coil resonates. Furthermore, by changing the ratio between the diagonal wave winding section and the lap winding section, it is possible to finely adjust the electrical characteristics of the coil.

[0013] In one embodiment of the present technology, in each of the multiple coils, the section that is displaced radially between the outermost layer and the innermost layer further has a wave winding section in which the direction of circumferential displacement on the first end face side and the direction of circumferential displacement on the second end face side are continuously the same, and the lap winding section may be located radially between the oblique wave winding section and the wave winding section.

[0014] In the above configuration, in addition to the oblique wave winding section and lap winding section, each coil further has a wave winding section. With this configuration, the frequency band in which the coil resonates can be further dispersed. Furthermore, by changing the ratio of the oblique wave winding section, the wave winding section, and the lap winding section, the electrical characteristics of the coil can be finely adjusted.

[0015] In one embodiment of the present technology, the multiple coils are 2Y or 4Y type parallel connected, and the starting points of coils of the same phase among the multiple coils may be located 12q+1 slots apart (q is a natural number).

[0016] According to the above configuration, the potential difference between adjacent coils can be reduced, and the surge voltage can be further reduced.

[0017] In each of the multiple coils according to one embodiment of the present technology, the coil segment located in the radially innermost layer within the slot may be made of Litz wire.

[0018] According to the above configuration, it is possible to reduce energy loss (e.g., copper eddy current loss) in the coil. In particular, in the stator of the present technology, the coil segment located in the innermost layer in the slot is connected to another coil segment located in the same innermost layer. Therefore, by using Litz wire only for the coil segment located in the innermost layer in the slot, it is possible to effectively reduce energy loss in the coil. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a perspective view of a stator 2 according to the first embodiment. [Figure 2] FIG. 2(A) shows the winding method of the first U-phase coil U1 in the first embodiment, and FIG. 2(B) shows the winding direction of the second U-phase coil U2. [Figure 3] FIG. 3A shows the winding method of the first U-phase coil U1 in the second embodiment, and FIG. 2B shows the winding direction of the second U-phase coil U2. [Figure 4] FIG. 4(A) shows the winding method of the first U-phase coil U1 in a modified example of the second embodiment, and FIG. 2(B) shows the winding direction of the second U-phase coil U2. [Figure 5] FIG. 5(A) shows the winding method of the first U-phase coil U1 in the third embodiment, and FIG. 2(B) shows the winding direction of the second U-phase coil U2. [Figure 6] FIG. 10 is a diagram schematically illustrating the joining method described in paragraph 0053. DETAILED DESCRIPTION OF THE INVENTION

[0020] (First embodiment) A stator 2 of a first embodiment will be described with reference to the drawings. The stator 2 of this embodiment is one of the components of an electric motor. The stator 2, together with a rotor (not shown), constitutes a power generating section of the electric motor. The configuration described in this embodiment is not limited to a three-phase AC motor, and can be similarly adopted in other types of electric motors. Furthermore, an electric motor using the stator 2 may be configured with a Y connection, a Delta connection, or an H connection.

[0021] As shown in FIG. 1 , the stator 2 of the first embodiment includes a stator core 10, a plurality of slots 12 provided in the stator core 10, and a plurality of coils 20. The stator core 10 is made of a soft magnetic material, such as electromagnetic steel. The stator core 10 has a cylindrical shape and extends axially between a first end face 10a and a second end face 10b. A plurality of slots 12 are formed on the inner peripheral surface of the stator core 10. The plurality of slots 12 are arranged circumferentially. Each of the plurality of slots 12 extends axially. The specific configuration of the stator core 10 is not particularly limited.

[0022] The multiple coils 20 include two U-phase coils, two V-phase coils, and two W-phase coils. The U-phase coils, V-phase coils, and W-phase coils are located at different circumferential positions on the stator core 10, but share other configurations. Each coil 20 is wound in a so-called distributed manner around the multiple slots 12. Each coil 20 is made up of multiple coil segments 22. A lead wire 26 is provided at the starting end of each coil 20, on the side of the first end surface 10a of the stator core 10. Note that when the multiple coils 20 are configured in a Y-connection, the ending ends of each coil 20 may be connected to each other, also on the side of the first end surface 10a of the stator core 10.

[0023] Each coil 20 is composed of a plurality of coil segments 22. Each coil segment 22 has a U-shape and is inserted into two slots 12 spaced a predetermined distance apart from the second end face 10b of the stator core 10. Each protrusion 24 of each coil segment 22 protrudes from the first end face 10a of the stator core 10. Each protrusion 24 of the coil segment 22 protruding from the first end face 10a is bent and joined to the corresponding protrusion 24 of another coil segment 22. In this way, each coil 20 is configured by connecting the plurality of coil segments 22 in series. Note that, in another embodiment, the plurality of coil segments 22 may be configured to fit together inside the slots 12. In this case, each coil segment 22 may have an I-shape (i.e., a linear shape) and may be bent at both end faces 10a, 10b of the stator core 10.

[0024] Referring to FIG. 2, the winding method of the multiple coils 20 in the stator 2 of the first embodiment will be described. FIG. 2(A) shows the winding method of the first U-phase coil of the multiple coils 20, and FIG. 2(B) shows the winding method of the second U-phase coil. In FIG. 2, the vertical columns indicate the positions of the slots 12 in the stator core 10. The horizontal columns indicate the circumferential positions of the coil segments 22 in each slot 12. Note that the higher the horizontal column, the more radially outward the coil segments 22 are located. As shown in FIG. 2, 48 slots 12 are provided on the inner peripheral surface of the stator core 10, and each slot 12 houses six layers of coil segments 22.

[0025] In FIG. 2A, symbol U1 indicates the start point of the first U-phase coil, and symbol N indicates the end point of the first U-phase coil. The solid arrows in FIG. 2A indicate the displacement of the first U-phase coil on the first end face 10a side of stator core 10, and the dashed arrows in FIG. 2A indicate the displacement of the first U-phase coil on the second end face 10b side of stator core 10. As shown in FIG. 2A, the first U-phase coil starts from the first layer (outermost layer) of the sixth slot and extends within the sixth slot from first end face 10a to second end face 10b of stator core 10. The first U-phase coil then displaces to the first layer of the first slot on the second end face 10b side of stator core 10, and extends within the first slot from second end face 10b to first end face 10a of stator core 10. Next, the first U-phase coil is displaced to the second layer of the 43rd slot on the side of the first end face 10a of the stator core 10, and extends within the 43rd slot from the first end face 10a of the stator core 10 toward the second end face 10b.

[0026] The first U-phase coil then displaces, in order, to the third layer of slot 37, the fourth layer of slot 31, the fifth layer of slot 25, and the sixth layer (innermost layer) of slot 19. The first U-phase coil then displaces to slot 12 in the sixth layer, then reverses its position and displaces to the fifth layer of slot 18. The first U-phase coil then displaces, in order, to the fourth layer of slot 24, the third layer of slot 30, the second layer of slot 36, and the first layer (outermost layer) of slot 42. The first U-phase coil then reverses its position and displaces to slot 37 in the first layer, then displaces to the second layer of slot 31. The first U-phase coil then repeats this same displacement until it reaches its end point, which is the second phase of slot 48.

[0027] As described above, the first U-phase coil has a start point (U1) and an end point (N) on the first end face 10a side of the stator core 10. In the first layer (outermost layer) and the sixth layer (innermost layer) in the radial direction within the slot 12, two coil segments 22 located in the same layer are connected to each other. Furthermore, the section that moves radially between the first layer and the sixth layer is an oblique wave winding section. In the oblique wave winding section, the direction of circumferential and radial displacement on the first end face 10a side and the direction of circumferential and radial displacement on the second end face 10b side are continuously aligned. Note that the relationship between the start point (U1) and the end point (N) in the first U-phase coil may be reversed.

[0028] As shown in FIG. 2B, the second U-phase coil is wound around slots 12 of stator core 10 in the same manner as the first U-phase coil. In FIG. 2B, symbol U2 indicates the starting point of the second U-phase coil, and symbol N indicates the ending point of the second U-phase coil. The solid arrows in FIG. 2B indicate the displacement of the second U-phase coil on the first end surface 10a side of stator core 10, and the dashed arrows in FIG. 2B indicate the displacement of the second U-phase coil on the second end surface 10b side of stator core 10. The relationship between the starting point (U2) and the ending point (N) of the second U-phase coil may also be reversed. Alternatively, the ending point (N) of the first coil and the starting point (U2) of the second coil may be connected to each other to form a 1Y connection. Alternatively, the end point (N) of the second coil and the start point (U1) of the first coil may be connected to each other to form a 1Y connection.

[0029] The two V-phase coils and the two W-phase coils are wound around the slots 12 of the stator core 10, similar to the two U-phase coils described above. That is, in the stator 2 of this embodiment, each coil 20 has a diagonal wave winding section. The winding method of the coil 20 in the diagonal wave winding section (i.e., diagonal wave winding) differs from both conventional lap winding and wave winding as winding methods of the coil 20. Therefore, when changing the winding method of the coil 20 for the purpose of suppressing resonance of the coil 20, this diagonal wave winding can be added as a new option in addition to conventional lap winding and wave winding. This increases the degree of freedom in adjusting the electrical characteristics of the stator 2, making it possible to more effectively suppress coil resonance.

[0030] In the stator 2 described above, the starting points (U1, U2) of the U-phase coils are located on the outermost layer, but the arrangement of the U-phase coils shown in Figures 2 and 3 may be reversed in the radial direction. That is, the starting points (U1, U2) of the U-phase coils may be located on the innermost layer. This also applies to the other embodiments described below.

[0031] Second Embodiment A stator of a second embodiment will be described with reference to Fig. 3. The stator of this embodiment has the same general structure as the stator 2 of the first embodiment as shown in Fig. 1. However, the stator of the second embodiment has a different winding method for the multiple coils 20 compared to the stator 2 of the first embodiment. As the other configurations are the same as the stator 2 of the first embodiment, a duplicated description will be omitted.

[0032] Fig. 3(A) shows the winding method for the first U-phase coil of the multiple coils 20, and Fig. 3(B) shows the winding method for the second U-phase coil. In Fig. 3, the vertical columns indicate the positions of the slots 12 in the stator core 10. The horizontal columns indicate the circumferential positions of the coil segments 22 in each slot 12. Note that the higher the horizontal column, the more radially outward the coil segments 22 are located. As shown in Fig. 3, 48 slots 12 are provided on the inner peripheral surface of the stator core 10, and each slot 12 houses six layers of coil segments 22.

[0033] In FIG. 3A, symbol U1 indicates the start point of the first U-phase coil, and symbol N indicates the end point of the first U-phase coil. The solid arrows in FIG. 3A indicate the displacement of the first U-phase coil on the first end face 10a side of stator core 10, and the dashed arrows in FIG. 3A indicate the displacement of the first U-phase coil on the second end face 10b side of stator core 10. As shown in FIG. 3A, the first U-phase coil starts from the first layer (outermost layer) of the fourth slot and extends within the fourth slot from first end face 10a to second end face 10b of stator core 10. The first U-phase coil then displaces to the first layer of the 47th slot on the second end face 10b side of stator core 10, and extends within the 47th slot from second end face 10b to first end face 10a of stator core 10. Next, the first U-phase coil is displaced to the second layer of the 41st slot on the side of the first end face 10a of the stator core 10, and extends within the 41st slot from the first end face 10a of the stator core 10 toward the second end face 10b.

[0034] Thereafter, the first U-phase coil is displaced to the third layer of the 35th slot on the side of second end face 10b of stator core 10, and extends within the 35th slot from second end face 10b toward first end face 10a of stator core 10. Next, the first U-phase coil reverses its direction and is displaced toward the fourth layer of the 41st slot on the side of first end face 10a of stator core 10, and extends within the 41st slot from first end face 10a toward second end face 10b of stator core 10. Then, the first U-phase coil reverses its direction again and is displaced toward the fifth layer of the 35th slot on the side of second end face 10b of stator core 10, and extends within the 35th slot from second end face 10b toward first end face 10a of stator core 10. Next, the first U-phase coil is displaced to the sixth layer (innermost layer) of the 29th slot on the first end face 10a side of the stator core 10, and extends within the 29th slot from the first end face 10a toward the second end face 10b of the stator core 10.

[0035] The first U-phase coil, wound using the above winding method from the first layer (outermost layer) of the fourth slot to the sixth layer (innermost layer) of the 29th slot, is displaced to the 22nd slot in the same sixth layer, then reverses its direction and displaces to the fifth layer of the 28th slot. The first U-phase coil then displaces, reversing its direction, to the fourth layer of the 34th slot, the third layer of the 28th slot, and the second layer of the 34th slot. The first U-phase coil then displaces to the first layer of the 40th slot, then reverses its direction and displaces to the 35th slot in the same first layer. The first U-phase coil then displaces to the second layer of the 29th slot. The first U-phase coil continues this same winding method, reversing its direction midway, until it reaches its end point, which is the second layer of the 46th slot.

[0036] As described above, the first U-phase coil has a starting point (U1) and an end point (N) on the first end face 10a side of the stator core 10. In the first layer (outermost layer) and the sixth layer (innermost layer) in the radial direction within the slot 12, two coil segments 22 located in the same layer are connected to each other. Furthermore, the sections of radial displacement between the first layer to the third layer and the fourth layer to the sixth layer are oblique wave winding sections, and the section of radial displacement between the third layer and the fourth layer is a lap winding section. In the oblique wave winding section, the circumferential and radial displacement directions on the first end face 10a side and the circumferential and radial displacement directions on the second end face 10b side are continuously aligned. However, in the lap winding section, the circumferential and radial displacement directions on the first end face 10a side and the circumferential and radial displacement directions on the second end face 10b side are opposite to each other and do not continuously line up.

[0037] As shown in Fig. 3(B), the second U-phase coil is also wound around slots 12 of stator core 10 in the same manner as the first U-phase coil. Note that in Fig. 3(B), symbol U2 indicates the start point of the second U-phase coil, and symbol N indicates the end point of the second U-phase coil. The solid arrows in Fig. 3(B) indicate the displacement of the second U-phase coil on the first end surface 10a side of stator core 10, and the dashed arrows in Fig. 3(B) indicate the displacement of the second U-phase coil on the second end surface 10b side of stator core 10.

[0038] The two V-phase coils and the two W-phase coils are wound around the slots 12 of the stator core 10, similar to the two U-phase coils described above. That is, in the stator 4 of this embodiment, each coil 20 has a diagonal wave winding section and a lap winding section. The winding style of the coil 20, which combines diagonal wave winding and lap winding, differs from the conventional lap winding, wave winding, and diagonal wave winding. Therefore, when changing the winding style of the coil 20 to suppress resonance of the coil 20, this winding style combining diagonal wave winding and lap winding can be added as a new option in addition to the conventional lap winding, wave winding, and diagonal wave winding. This further increases the degree of freedom in adjusting the electrical characteristics of the stator 4, making it possible to more effectively suppress coil resonance.

[0039] (Modification of Second Embodiment) A stator according to a modification of the second embodiment will be described with reference to Fig. 4. The stator according to this embodiment has the same general structure as the stator 4 according to the second embodiment as shown in Fig. 1. However, in the stator according to the modification of the second embodiment, the proportion of the section in which the multiple coils 20 are wound in lap winding is changed compared to the stator 4 according to the second embodiment. As the other configurations are the same as those of the stator 4 according to the second embodiment, a duplicated description will be omitted.

[0040] Fig. 4(A) shows the winding method for the first U-phase coil of the multiple coils 20, and Fig. 4(B) shows the winding method for the second U-phase coil. In Fig. 4, the vertical columns indicate the positions of the slots 12 in the stator core 10. The horizontal columns indicate the circumferential positions of the coil segments 22 in each slot 12. Note that the higher the horizontal column, the more radially outward the coil segments 22 are located. As shown in Fig. 4, 48 slots 12 are provided on the inner peripheral surface of the stator core 10, and each slot 12 houses six layers of coil segments 22.

[0041] In FIG. 4A, symbol U1 indicates the start point of the first U-phase coil, and symbol N indicates the end point of the first U-phase coil. The solid arrows in FIG. 4A indicate the displacement of the first U-phase coil on the first end face 10a side of stator core 10, and the dashed arrows in FIG. 4A indicate the displacement of the first U-phase coil on the second end face 10b side of stator core 10. As shown in FIG. 4A, the first U-phase coil starts from the first layer (outermost layer) of the fourth slot and extends within the fourth slot from first end face 10a to second end face 10b of stator core 10. The first U-phase coil then displaces to the first layer of the 47th slot on the second end face 10b side of stator core 10, and extends within the 47th slot from second end face 10b to first end face 10a of stator core 10. Next, the first U-phase coil is displaced to the second layer of the 41st slot on the side of the first end face 10a of the stator core 10, and extends within the 41st slot from the first end face 10a of the stator core 10 toward the second end face 10b.

[0042] Thereafter, the first U-phase coil is displaced to the third layer of the 35th slot on the side of second end face 10b of stator core 10, and extends within the 35th slot from second end face 10b toward first end face 10a of stator core 10. Next, the first U-phase coil reverses its direction and is displaced toward the fourth layer of the 41st slot on the side of first end face 10a of stator core 10, and extends within the 41st slot from first end face 10a toward second end face 10b of stator core 10. Then, the first U-phase coil reverses its direction again and is displaced toward the fifth layer of the 35th slot on the side of second end face 10b of stator core 10, and extends within the 35th slot from second end face 10b toward first end face 10a of stator core 10. Next, the first U-phase coil reverses direction and displaces to the sixth layer (innermost layer) of the 41st slot on the first end face 10a side of the stator core 10 in the same procedure as above, and extends within the 41st slot from the first end face 10a to the second end face 10b of the stator core 10.

[0043] The first U-phase coil, wound using the above winding method from the first layer (outermost layer) of slot 4 to the sixth layer (innermost layer) of slot 41, displaces to slot 34 in the same sixth layer, and then displaces to slot 28's fifth layer. The first U-phase coil then displaces while reversing its direction, moving to slot 34's fourth layer, slot 28's third layer, and slot 2's second layer. The first U-phase coil then displaces to slot 40's first layer, then displaces to slot 35 in the same first layer, with the direction reversed. The first U-phase coil then displaces to slot 29's second layer. The first U-phase coil continues this same winding method, reversing its direction midway, until it reaches its end point, located in slot 46's second layer.

[0044] As described above, the first U-phase coil has a starting point (U1) and an end point (N) on the first end face 10a side of the stator core 10. In the first layer (outermost layer) and the sixth layer (innermost layer) in the radial direction within the slot 12, two coil segments 22 located in the same layer are connected to each other. Furthermore, the section between the first layer and the third layer where the coils are displaced radially is an oblique wave winding section, and the section between the third layer and the sixth layer where the coils are displaced radially is a lap winding section. In the oblique wave winding section, the circumferential and radial displacement directions on the first end face 10a side and the circumferential and radial displacement directions on the second end face 10b side are continuously aligned. However, in the lap winding section, the circumferential and radial displacement directions on the first end face 10a side and the circumferential and radial displacement directions on the second end face 10b side are opposite to each other and do not continuously line up.

[0045] As shown in FIG. 4B, the second U-phase coil is wound around slots 12 of stator core 10 in the same manner as the first U-phase coil. In FIG. 4B, reference symbol U2 indicates the start point of the second U-phase coil, and reference symbol N indicates the end point of the second U-phase coil. The solid arrows in FIG. 4B indicate the displacement of the second U-phase coil on the first end surface 10a side of stator core 10, and the dashed arrows in FIG. 4B indicate the displacement of the second U-phase coil on the second end surface 10b side of stator core 10.

[0046] The two V-phase coils and the two W-phase coils are wound around the slots 12 of the stator core 10, similar to the two U-phase coils described above. The stator 6 of this embodiment also illustrates an example in which the proportions of the diagonal wave winding section and the lap winding section in each of the coils 20 of the stator 4 of the second embodiment are changed. The winding method of the coil 20 of the stator 6 differs from the conventional lap winding, wave winding, diagonal wave winding, and stator 4, and the electrical characteristics are also different. Therefore, when changing the winding method of the coil 20 to suppress resonance of the coil 20, options can be increased by changing the proportions of the diagonal wave winding and lap winding according to specifications. This further increases the degree of freedom in adjusting the electrical characteristics of the stator 6, enabling more effective suppression of coil resonance.

[0047] (Third embodiment) A stator of a third embodiment will be described with reference to Fig. 5. The stator of this embodiment generally has the structure shown in Fig. 1, similar to the stator 2 of the first embodiment. However, in the stator of the third embodiment, the spacing between the circumferential positions of the slots 12 at the starting points U1 and U2 of the coils 20 of each phase is changed compared to the stator 2 of the first embodiment. The other configurations are the same as those of the stator 2 of the first embodiment, so duplicated descriptions will be omitted.

[0048] FIG. 5(A) shows the winding method for the first U-phase coil of the multiple coils 20, and FIG. 3(B) shows the winding method for the second U-phase coil. In FIG. 5, the vertical columns indicate the positions of the slots 12 in the stator core 10. The horizontal columns indicate the circumferential positions of the coil segments 22 in each slot 12. Note that the higher the horizontal column, the more radially outward the coil segments 22 are located. As shown in FIG. 5, 48 slots 12 are provided on the inner peripheral surface of the stator core 10, and each slot 12 houses six layers of coil segments 22.

[0049] 5A, symbol U1 indicates the start point of the first U-phase coil, and symbol N indicates the end point of the first U-phase coil. The solid arrows in the figure indicate the displacement of the first U-phase coil on the side of first end face 10a of stator core 10, and the dashed arrows in the figure indicate the displacement of the first U-phase coil on the side of second end face 10b of stator core 10. As shown in FIG. 5A, the first U-phase coil is wound in a diagonal wave manner between the first layer (outermost layer) of slot 4 and the sixth layer (innermost layer) of slot 12 of stator core 10, following the same procedure as stator 2 of the first embodiment, with the first layer (outermost layer) of slot 4 and the second layer of slot 46 as the end point.

[0050] As shown in FIG. 5(B), the second U-phase coil is also wound around slots 12 of stator core 10 in the same manner as the first U-phase coil. In FIG. 5(B), symbol U2 indicates the starting point of the second U-phase coil, and symbol N indicates the ending point of the second U-phase coil. The solid arrows in FIG. 5(B) indicate the displacement of the second U-phase coil on the first end surface 10a side of stator core 10, and the dashed arrows in FIG. 5(B) indicate the displacement of the second U-phase coil on the second end surface 10b side of stator core 10. As shown in FIGS. 5(A) and 5(B), starting point U1 of the first U-phase coil and starting point U2 of the second U-phase coil are wound around slots 12 of stator core 10 with a gap of 25 slots between them.

[0051] Similarly to the two U-phase coils described above, the two V-phase coils and the two W-phase coils are wound around the slots 12 of the stator core 10, with the starting points of the first V-phase and W-phase coils and the starting points of the second V-phase and W-phase coils spaced 25 slots apart. In the configuration of this embodiment, the starting points of two coils of the same phase are spaced 12q+1 slots apart (q is a natural number, q=2 in this embodiment). This configuration reduces the potential difference between adjacent coils, further reducing surge voltages. Therefore, when changing the winding method of the coil 20 to suppress resonance of the coil 20, a new option is available: a winding method in which the starting points of each coil of the same phase are spaced 12q+1 slots apart (q is a natural number), in addition to the conventional lap winding, wave winding, and diagonal wave winding. This further increases the degree of freedom in adjusting the electrical characteristics of the stator 8, enabling more effective suppression of coil resonance.

[0052] Furthermore, in the stators 2, 4, 6, and 8 of the first to third embodiments, the coil segments 22 wound in the sixth layer (innermost layer) of the slots 12 of the stator core 10 may be made of Litz wire. This configuration can reduce copper eddy loss in the coils 20 of each phase. Note that Litz wire may be used not only in the sixth layer of each slot 12, but also in layers outside the sixth layer.

[0053] A method for joining the protruding portions 24 of the coil segments 22 in the stators 2, 4, 6, and 8 of the first to third embodiments will be described with reference to FIG. 6 . As shown in FIG. 6 , the protruding portions 24 of the coil segments 22 in the stators 2, 4, 6, and 8 of the first to third embodiments are joined using TIG welding. When TIG welding a U-shaped coil segment 22, the protruding portions 24 to be joined are generally clamped by a relatively large electrode that also functions as a shielding plate. In contrast, as shown in FIG. 6 , in a coil segment 22 in a diagonal wave winding section, two joints 28 located at both ends of the coil segment 22 are positioned at different positions in the circumferential direction. Therefore, in the joining method shown in FIG. 6 , a clamp 32 that shields and fixes the joint 28 located at one end and an electrode 30 that clamps the joint 28 located at the other end are prepared independently of each other. This configuration allows the clamp 32 and the electrode 30 to be miniaturized, and also reduces the length of the joint 28 of the coil segment 22 to which they are attached. This allows the stators 2, 4, 6, and 8 to be made smaller.

[0054] Although the embodiments of the present technology have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0055] 2, 4, 6, 8: Stator, 10: Stator core, 12: Slot, 20: Coil, 22: Coil segment, 24: Protrusion, 26: Lead wire, 28: Joint, 30: Electrode, 32: Clamp,

Claims

1. A stator of an electric motor, a cylindrical stator core extending in the axial direction between a first end surface and a second end surface; a plurality of slots provided on an inner peripheral surface of the stator core, arranged along a circumferential direction, and each extending along the axial direction; a plurality of coils wound in a distributed manner around the plurality of slots, each of the coils being composed of a plurality of coil segments; Equipped with When the number of the plurality of slots is n and the number of magnetic poles of the rotor is P, the relationship n = 6p is satisfied, In each of the plurality of slots, the coil segments are arranged in a radial direction to form a plurality of layers, In each of the plurality of coils, a start point and an end point are provided on the first end face side of the stator core, In the radially outermost layer and the radially innermost layer in the slot, two coil segments located in the same layer are connected to each other, The section displaced in the radial direction between the outermost layer and the innermost layer includes an oblique wave winding section in which the direction of displacement in the circumferential direction and the radial direction on the first end surface side and the direction of displacement in the circumferential direction and the radial direction on the second end surface side are continuously coincident with each other. Stator.

2. In each of the plurality of coils, the section displaced in the radial direction between the outermost layer and the innermost layer in the slot further includes a lap winding section in which the direction of displacement in the circumferential direction on the first end face side and the direction of displacement in the circumferential direction on the second end face side are reversed to each other. The stator according to claim 1 .

3. In each of the plurality of coils, the section displaced in the radial direction between the outermost layer and the innermost layer further includes a wave winding section in which a direction of displacement in the circumferential direction on the first end surface side and a direction of displacement in the circumferential direction on the second end surface side are continuously aligned, The lap winding section is located between the oblique wave winding section and the wave winding section in the radial direction. The stator according to claim 2 .

4. the plurality of coils are connected in parallel in a 2Y or 4Y configuration; Among the plurality of coils, the starting points of coils of the same phase are positioned apart by 12q+1 slots (q is a natural number). The stator according to claim 1 .

5. In each of the plurality of coils, a coil segment located in the radially innermost layer within the slot is made of a Litz wire. The stator according to claim 1 .

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