Stator

Abstract

To provide a stator having a stator winding in which occurrence of circulating current between conductors of split or dislocated windings can be prevented.SOLUTION: According to an embodiment, a stator 100 includes a stator core 110 and a stator winding 120. The stator winding 120 includes, in each phase: a plurality of coil segments respectively having a linear portion housed in a first stator slot 111a, a linear portion housed in a second stator slot 111b, and a bridge portion connecting these linear portions; and a plurality of connection portions connecting the coil segments in series on an outer side of another end. A parallel portion coil segment 131 on the radially innermost portion has a first split segment 141 and a second split segment 142. The first split segment 141 and the second split segment 142 intersect with each other between the first stator slot 111a and the second stator slot 111b. The first stator slot 111a and the second stator slot 111b are deviated from each other by slots of one magnetic pole in the circumferential direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a stator. [Background technology]

[0002] During operation of a rotating electric machine, magnetic flux is generated that crosses the stator teeth in the circumferential direction, and this magnetic flux generates a circulating current in part of the stator winding, which increases loss.

[0003] A known method for preventing the generation of this circulating current is to divide the radially inner conductor into a parallel circuit and then transpose one of the divided conductors, i.e., cross the conductors. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7186927 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned technology discloses, for example, an example in which, when the number of slots corresponding to one magnetic pole is six, the divided and transposed windings are arranged in slots five slots apart, and an example in which the divided and transposed windings are arranged in slots seven slots apart.

[0006] However, in these cases, the phases of the potential differences generated in the conductors of each split or transposed winding are different from each other, which causes a small amount of circulating current to remain between the split or transposed windings, resulting in losses.

[0007] An object of an embodiment of the present invention is to provide a stator having a stator winding that can prevent the generation of circulating current between conductors of a split or transposed winding. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the stator according to this embodiment includes a cylindrical stator core having a plurality of axially extending stator slots formed on its inner peripheral surface at intervals in the circumferential direction, and a stator winding including, for each phase, a plurality of coil segments each using a flat rectangular conductor and having a straight portion accommodated in a first stator slot and a second stator slot that are different from each other among the plurality of stator slots, and a bridging portion connecting the two straight portions outside a first end of the stator core in the axial direction, and a plurality of connecting portions connecting the plurality of coil segments in series outside a second end of the stator core in the axial direction, wherein the radially innermost coil segment is electrically The parallel portion coil segment has a first split segment and a second split segment that are parallel to each other, and in the first stator slot, the straight portion of the first split segment is arranged in a first layer when viewed from the radial inside of the stator core, and the straight portion of the second split segment is arranged in a second layer adjacent to the radial outside of the first layer, and in the second stator slot, the straight portion of the first split segment is arranged in the second layer, and the straight portion of the second split segment is arranged in the first layer, and the first stator slot and the second stator slot in which the parallel portion coil segment is arranged are offset in the circumferential direction by the number of slots equivalent to one magnetic pole. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of a rotating electric machine having a stator according to an embodiment; [Figure 2] FIG. 2 is a conceptual explanatory diagram showing a part of a stator core and a stator winding of a stator according to an embodiment. [Figure 3] FIG. 10 is a conceptual explanatory diagram showing a part of a stator winding of a comparative example to the stator according to the embodiment. [Figure 4] 10 is a table illustrating differences between the stator windings of the stator according to the embodiment and a comparative example. [Figure 5]10 is a table including comparative examples for explaining the effects of the stator winding of the stator according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a stator according to an embodiment of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by the same reference numerals, and overlapping descriptions will be omitted.

[0011] FIG. 1 is a cross-sectional view showing an example of the configuration of a rotating electrical machine 1 having a stator 100 according to an embodiment.

[0012] The rotating electric machine 1 includes a rotor 10 , a bearing 21 , a bearing bracket 22 , a frame 23 , and a stator 100 .

[0013] The rotor 10 has a rotor shaft 11 extending in a direction (axial direction) parallel to the rotation axis CL, a rotor core 12 attached to the radial outside of the rotor shaft 11, and a permanent magnet 13 arranged in the rotor core 12. Note that although Fig. 1 illustrates a permanent magnet type synchronous machine as an example of the rotor 10, it may be a wound type or an induction type rotor.

[0014] The stator 100 has a stator core 110 provided radially outside the rotor core 12 , and a stator winding 120 wound around the stator core 110 .

[0015] The stator winding 120 is a winding using a rectangular conductor insulated with, for example, enamel. The stator winding 120 forms a multi-phase, for example, three-phase, circuit. Each phase of the stator winding 120 has multiple coil segments 130 and connection portions 125 that connect the coil segments 130 together.

[0016] Each coil segment 130 has two straight portions 130a and a bridge portion 130b connecting the two straight portions 130a. The bridge portion 130b of each coil segment 130 is disposed outside the first axial end 110a of the stator core 110. The ends of the two straight portions 130a that are not connected to the bridge portion 130b protrude outside the second axial end 110b of the stator core 110. The two straight portions 130a are connected to other coil segments 130 outside the second end 110b by a connection portion 125. Here, the connection portion 125 is, for example, a welded portion or a brazed portion. Note that the straight portion 130a outside the second end 110b is partially shaped along the circumferential direction and is not linear; however, in the following description, this is not distinguished and is described as part of the straight portion 130a for convenience.

[0017] FIG. 2 is a conceptual explanatory diagram showing a part of the stator core 110 and the stator winding 120 of the stator 100 according to the embodiment.

[0018] A plurality of stator slots 111 are formed in the stator core 110 at intervals in the circumferential direction. Adjacent stator slots 111 form stator teeth 112. Fig. 2 shows some of the plurality of stator slots 111 and stator teeth 112. The straight portions 130a of the coil segments 130 are housed in each stator slot 111 so as to be stacked in the radial direction.

[0019] The stator slots 111 shown in the figure are numbered 1 to 7 within squares. Each number refers to the first stator slot 111 through the seventh stator slot 111. Here, the first through sixth stator slots 111 correspond to one pole corresponding to three phases. Therefore, the seventh stator slot 111 is the stator slot 111 belonging to the next pole and corresponds to the first stator slot 111 of the adjacent pole. In this way, the stator slots 111 of a given pole and an adjacent pole in the same order are expressed as being offset circumferentially by the number of slots equivalent to one magnetic pole, or as being offset by one pole. Furthermore, if they are offset by one magnetic pole, for example, they are also expressed as being offset by six slots.

[0020] Now, the first stator slot 111 in FIG. 2 will be called the first stator slot 111a, and the seventh stator slot 111 will be called the second stator slot 111b.

[0021] Regarding the stator winding 120, Fig. 2 shows the elements that make up the coil segment 130 and its straight portions 130a and bridge portions 130b shown in Fig. 1. The following will explain the correspondence with Fig. 1.

[0022] The coil segment 130 includes a parallel portion coil segment 131, a coil segment 132, a coil segment 133, and other coil segments not numbered in FIG. 2, and the coil segment 130 is a general term for these.

[0023] Here, the parallel portion coil segment 131 and the other coil segments 132 and 133 use rectangular conductors as described above.

[0024] As shown in FIG. 2, the straight portion 130a of the coil segment 130 includes a straight portion 131a of the parallel portion coil segment 131, a straight portion 132a of the coil segment 132, a straight portion 133a of the coil segment 133, and other straight portions.

[0025] 2, the straight portion 131a of the parallel portion coil segment 131 is housed at the radially innermost portion of the stator slot 111. Radially outside the straight portion of the parallel portion coil segment 131, the straight portion 132a of the coil segment 132, the straight portion 133a of the coil segment 133, and other straight portions are housed in this order.

[0026] Similarly, the bridging portion 130b of the coil segment 130 includes bridging portions of the parallel portion coil segment 131, the coil segment 132, the coil segment 133, and other coil segments not numbered in Fig. 2. Of these, only the bridging portion 131b of the parallel portion coil segment 131 is shown in Fig. 2.

[0027] The parallel section coil segment 131, whose straight section is housed in the innermost part of the stator slot 111, has a first divided segment 141 and a second divided segment 142. Alternatively, it can be said that the parallel section coil segment 131 is divided into the first divided segment 141 and the second divided segment 142.

[0028] The thickness t1 in the radial direction of the flat rectangular conductor of each of the first divided segment 141 and the second divided segment 142 constituting the parallel portion coil segment 131 is substantially the same.

[0029] Furthermore, the radial thickness t1 of the flat rectangular conductor of each of the first divided segment 141 and the second divided segment 142 is substantially half the radial thickness t0 of the flat rectangular conductor of the coil segment 130 other than these.

[0030] Here, "substantially" means that the same dimensions are intended to be obtained in the design, and that they match within the range of manufacturing error. Manufacturing error here includes errors in processing, assembly, measurement, etc.

[0031] The first divided segment 141 has straight portions 141a and 141b and a bridge portion 141c connecting them. The second divided segment 142 has straight portions 142a and 142b and a bridge portion 142c connecting them. The bridge portion 141c and the bridge portion 142c are collectively referred to as the bridge portion 131b.

[0032] The straight portion 141a of the first divided segment 141 and the straight portion 142a of the second divided segment 142 include portions that are housed in the first stator slot 111a. In addition, the straight portion 141b of the second divided segment 141 and the straight portion 142b of the second divided segment 142 include portions that are housed in the second stator slot 111b.

[0033] In the first stator slot 111a, the straight portion 141a of the first split segment 141 is arranged in the innermost layer, and the straight portion 142a of the second split segment 142 is arranged adjacent to it on the radially outer side. Meanwhile, in the second stator slot 111b, the straight portion 142b of the second split segment 142 is arranged in the innermost layer, and the straight portion 141b of the first split segment 141 is arranged adjacent to it on the radially outer side.

[0034] That is, the first split segment 141 and the second split segment 142 of the split parallel portion coil segment 131 are arranged to intersect with each other. More specifically, on the outside of the first end portion 110a of the stator core 110, the bridging portion 141c of the first split segment 141 and the bridging portion 142c of the second split segment 142 are arranged to intersect with each other. The fact that the first split segment 141 and the second split segment 142 intersect with each other can also be said to mean that one of them is transposed.

[0035] Because the first stator slot 111a and the second stator slot 111b are offset by exactly one pole, currents of the same phase flow through the straight portions of the parallel section coil segment 131 housed in the first stator slot 111a and the second stator slot 111b. Note that for the coil segments 130 other than the parallel section coil segment 131, the first stator slot 111a and the second stator slot 111b do not need to be offset by one pole in the circumferential direction. For example, for multiple coil segments 130 other than the parallel section coil segment 131, the first stator slot 111a and the second stator slot 111b may be longer or shorter than one pole in the circumferential direction, or a combination of these may be used.

[0036] Outside the second end 110b of the stator core 110, the straight portion 141a of the first split segment 141 protruding from within the first stator slot 111a and the straight portion 142a of the second split segment 142 are connected to the first coil segment 151 by the first connecting portion 151m.

[0037] In addition, the straight portion 141b of the first split segment 141 and the straight portion 142b of the second split segment 142 protruding from within the second stator slot 111b are connected to the second coil segment 152 by the second connecting portion 152m.

[0038] In this way, the first divided segment 141 and the second divided segment 142 are connected to each other by the first connecting portion 151m and the second connecting portion 152m, and are wired in parallel between the first connecting portion 151m and the second connecting portion 152m. The first connecting portion 151m and the second connecting portion 152m are specific examples of the connecting portion 125 shown in FIG. 1.

[0039] Here, the first coil segment 151 and the second coil segment 152 refer to coil segments other than the parallel portion coil segment 131. What the first coil segment 151 and the second coil segment 152 are depends on the connection method of the stator winding 120. Therefore, the first coil segment 151 and the second coil segment 152 may also be the coil segment 132 or the coil segment 133.

[0040] 3 is a conceptual explanatory diagram showing a portion of a stator winding that is a comparative example to the stator winding 120 of the stator 100 according to the embodiment. For ease of explanation, the same names and symbols as in FIG. 2 are used in FIG. 3 for parts that are common to the embodiment.

[0041] In the comparative example, as in the embodiment, the first split segment 141 has straight portions 141a, 141b and a bridging portion 141c connecting them, and the second split segment 142 has straight portions 142a, 142b and a bridging portion 142c connecting them.

[0042] As in the embodiment, the straight portion 141a of the first divided segment 141 and the straight portion 142a of the second divided segment 142 are housed in the first stator slot 111a.

[0043] Also, the straight portion 141b of the second divided segment 141 and the straight portion 142b of the second divided segment 142 are housed in the second stator slot 111b, similar to the embodiment.

[0044] Also, the first divided segment 141 and the second divided segment 142 are arranged so as to intersect with each other, similar to the embodiment.

[0045] However, the comparative example differs from the embodiment in the following respects.

[0046] That is, in the embodiment, the first stator slot 111a is the first stator slot 111, and the second stator slot is the seventh stator slot 111. That is, the first stator slot 111a and the second stator slot 111b are shifted by exactly one pole.

[0047] On the other hand, in the comparative example, the first stator slot 111a is the first stator slot 111, and the second stator slot 111b is the sixth stator slot 111. In this case, the first stator slot 111a and the second stator slot 111b are not shifted by one pole, but the shift is small by one slot.

[0048] FIG. 4 is Table 1 explaining the differences between the stator winding of the embodiment and the comparative example.

[0049] Each column in Table 1, that is, the horizontal direction, No. 1 to No. 8, is the number of the stator slot 111 shown in FIGS. 2 and 3.

[0050] The potential difference of the first layer conductor is the potential difference generated in the straight portion 130a accommodated in the first layer of each stator slot 111, that is, the potential difference between both sides of the straight portion 130a of the first layer. Further, the potential difference of the second layer conductor is the potential difference generated in the straight portion 130a accommodated in the second layer of each stator slot 111, that is, the potential difference between both ends of the straight portion 130a of the second layer. Here, the first layer is the order of being sequentially laminated from the radially inner side to the radially outer side of the stator slot 111 when viewed from the inside of the stator core 110. That is, from the radially inner side, they are sequentially the first layer, the second layer, the third layer, and so on.

[0051] These potential differences are generated by the cross-linking magnetic flux that crosses the stator teeth 112 in the circumferential direction in the stator core 110 during the operation of the rotating electrical machine 1.

[0052] <Case of No. 1 and No. 6 (Comparative Example)> As described above, the straight portion 141a of the first split segment 141 is housed in the first layer of the No. 1 stator slot 111, i.e., the first stator slot 111a. In this case, the potential difference V1a generated in the straight portion 141a is defined as V1. Furthermore, the straight portion 142a of the second split segment 142 is housed in the second layer of the first stator slot 111a. In this case, the potential difference generated in the straight portion 142a is a different value from the potential difference generated in the straight portion 141a. If the difference with the potential difference generated in the straight portion 141a is defined as ΔV1, the potential difference V2a generated in the straight portion 142a is (V1 + ΔV1).

[0053] Next, assume that the straight portion 141b of the first divided segment 141 and the straight portion 142b of the second divided segment 142 are respectively housed in the second and first layers of any one of stator slots 111 No. 2 to No. 8. In other words, assume that the second stator slot 111b is any one of stator slots 111 No. 2 to No. 8.

[0054] For example, if the No. 6 stator slot 111 is the second stator slot 111b, the potential difference V2b generated in the straight portion 142b of the second divided segment 142 housed in the first layer is V6. Also, the potential difference V1b generated in the straight portion 141b of the first divided segment 141 housed in the second layer is (V6 + ΔV6). In this way, ΔVj (j = 1 to 6), which is the difference between the potential differences generated in the first and second layers in the j-th stator slot 111, has a different value among the No. 1 to No. 6 stator slots 111.

[0055] The potential difference VV1 generated in the first divided segment 141 is the sum of the potential difference V1a generated in the straight portion 141a in the first stator slot 111a and the potential difference V1b generated in the straight portion 141b in the second stator slot 111b. Therefore, the potential difference VV1 generated in the first divided segment 141 is given by the following equation (1): VV1=V1a+V1b=V1+(V6+ΔV6) …(1)

[0056] The potential difference VV2 generated in the second divided segment 142 is the sum of the potential difference V2a generated in the straight portion 142a in the first stator slot 111a and the potential difference V2b generated in the straight portion 142b in the second stator slot 111b. Therefore, the potential difference VV2 generated in the second divided segment 142 is given by the following equation (1). VV2 = V2a + V2b = (V1 + ΔV1) + V6 …(2)

[0057] Therefore, the potential difference VV1 generated in the first divided segment 141 and the potential difference VV2 generated in the second divided segment 142 are different values. As a result, a circulating current will be generated in the first divided segment 141 and the second divided segment 1 that are connected in parallel and constitute the parallel portion coil segment 131.

[0058] <Case of No.1 and No.7 (this embodiment)> This is the case where the second stator slot 111b is the No.7 stator slot 111. In this case, as described above, the second stator slot 111b is shifted by one pole from the first stator slot 111a. In this case, the straight portion 141b of the first divided segment 141 and the straight portion 142b of the second divided segment 142 are respectively housed in the second layer and the first layer of the No.7 stator slot 111.

[0059] In the case of the No.7 stator slot 111, since it is shifted by one pole from the No.1 stator slot 111, the potential difference V2b generated in the straight portion 142b of the second divided segment 142 in the first layer is V1, and the potential difference V1b generated in the straight portion 141b of the first divided segment 141 in the second layer is (V1 + ΔV1). Therefore, the potential difference VV1 generated in the first divided segment 141 is given by the following equation (3). VV1 = V1a + V1b = V(1) + (V1 + ΔV1) = 2V1 + ΔV1…((3)

[0060] Also, the potential difference VV2 generated in the second divided segment 142 is given by the following equation (4). VV2 = V2a + V2b = (V1 + ΔV1) + V1 = 2V1 + ΔV1…(4)

[0061] As shown in equations (3) and (4), the potential difference VV1 generated in the first divided segment 141 and the potential difference VV2 generated in the second divided segment 142 are equal.

[0062] Therefore, no circulating current flows through the first divided segment 141 and the second divided segment 142 which are connected in parallel and form the parallel portion coil segment 131.

[0063] Even when taking into account manufacturing errors in the coil, almost no circulating current flows. Therefore, it can be said that no circulating current actually flows.

[0064] FIG. 5 is Table 2 including comparative examples that explain the effects of the stator winding 120 of the stator 100 according to the embodiment.

[0065] Each column in Table 2 shown in FIG. 5 indicates the number of the second stator slot 111b, and shows No. 6, No. 7, and No. 8, respectively. Here, the case where the number of the second stator slot 111b is No. 7 corresponds to this embodiment in which the second stator slot 111b is shifted by one pole from the first stator slot 111b. The cases where the numbers of the second stator slot 111b are No. 6 and No. 8 correspond to comparative examples.

[0066] Each numerical value is the ratio Rv obtained by dividing the difference in potential difference between the two parallel conductors, i.e., the first divided segment 141 and the second divided segment 142, by the average value of the respective potential differences. In other words, Rv is the value (%) of (VV2-VV1) / [(VV1+VV2) / 2].

[0067] <Comparative Example> When the second stator slot 111b is No. 6, the values ​​are given by the following formulas (1) and (2) as described above. VV1=V1+(V6+ΔV6) …(1) VV2=(V1+ΔV1)+V6 …(2)

[0068] Therefore, Rv6 when the second stator slot 111b is No. 6 is given by the following equation (5). Rv6 =(ΔV6-ΔV1) / [V1+V6+(ΔV1+ΔV6) / 2]...(5)

[0069] This value is 0.7% as shown in Table 2 of Fig. 5. When the second stator slot 111b is No. 8, Rv8 is also 0.7%.

[0070] <Present Embodiment> When the second stator slot 111b is No. 7, the values ​​are given by the following equations (3) and (4) as described above. VV1=V1+(V1+ΔV1) …(3) VV2=(V1+ΔV1)+V1 …(4)

[0071] Therefore, when the second stator slot 111b is No. 7, the numerator value of Rv7 is zero because VV1 and VV2 are equal, and the value is 0%, as shown in Table 2.

[0072] As described above, in the comparative example, the potential difference between the first divided segment 141 and the second divided segment 142 is approximately 0.7%, which generates a circulating current. On the other hand, in this embodiment, there is no potential difference between the first divided segment 141 and the second divided segment 142, and therefore no circulating current is generated.

[0073] According to the embodiment described above, it is possible to provide a stator having a stator winding that can prevent the generation of circulating current between the conductors of the divided and transposed winding.

[0074] [Other embodiments] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. Furthermore, the embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0075] 1... rotating electric machine, 10... rotor, 11... rotor shaft, 12... rotor core, 13... permanent magnet, 21... bearing, 22... bearing bracket, 23... frame, 100... stator, 110... stator core, 110a... first end, 110b... second end, 111... stator slot, 111a... first stator slot, 111b... second stator slot, 112... stator teeth, 120... stator winding, 125... connection portion, 130... coil segment, 130a... straight portion , 130b...bridge portion, 131...parallel portion coil segment, 132...coil segment, 132a...straight portion, 133...coil segment, 133a...straight portion, 141...first divided segment, 141a, 141b...straight portion, 141c...bridge portion, 142...second divided segment, 142a, 142b...straight portion, 142c...bridge portion, 151...first coil segment, 151m...first connecting portion, 152...second coil segment, 152m...second connecting portion

Claims

1. a cylindrical stator core having a plurality of axially extending stator slots formed on its inner circumferential surface at intervals in the circumferential direction; a stator winding for each phase, the stator winding using a rectangular conductor and including a plurality of coil segments each having a straight portion accommodated in a first stator slot and a second stator slot that are different from each other among the plurality of stator slots and a bridging portion connecting the two straight portions outside a first end of the stator core in the axial direction, and a plurality of connecting portions connecting the plurality of coil segments in series outside a second end of the stator core in the axial direction; A stator comprising: the radially innermost coil segment is a parallel portion coil segment having a first divided segment and a second divided segment electrically parallel to each other, In the first stator slot, the straight portion of the first divided segment is arranged in a first layer when viewed from the inside in the radial direction of the stator core, and the straight portion of the second divided segment is arranged in a second layer adjacent to the outside in the radial direction of the first layer, In the second stator slot, the straight portion of the first divided segment is arranged in the second layer, and the straight portion of the second divided segment is arranged in the first layer, the first stator slot and the second stator slot in which the parallel portion coil segment is arranged are offset in the circumferential direction by the number of slots equivalent to one magnetic pole; A stator characterized by:

2. the straight portion of the first divided segment and the straight portion of the second divided segment protruding from the first stator slot to the outside of the second end of the stator core are connected to a first coil segment of the coil segments by a first connection portion of the connection portions, the straight portion of the first divided segment and the straight portion of the second divided segment protruding from the second stator slot to the outside of the second end of the stator core are connected to a second coil segment of the coil segments by a second connection portion of the connection portions; 2. The stator according to claim 1 .

3. 2. The stator of claim 1, wherein the radial thickness of the flat rectangular conductor of the first divided segment and the second divided segment of the parallel portion coil segment is substantially half the radial thickness of the flat rectangular conductor of the coil segment arranged radially outward from the parallel portion coil segment.

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