Modular hairpin winding group and stator core structure

Abstract

A modular hairpin winding group is provided. [Solution] The modular hairpin winding group includes four types of hairpin windings u1 to u3 and two rectangular wires I1 and I2, and forms a phase unit 210 of at least one phase winding group. The phase unit is laid along only a part of the circumference of the stator core. Each phase unit is regarded as a single modular structure, simplifying the wiring design and reducing the difficulty of installation.

Description

[Technical field]

[0001] This invention relates to wiring of hairpin winding groups, and more particularly to electronic wiring. [Background technology]

[0002] The stator of a three-phase induction motor has three coil windings that are symmetrically distributed. After the coil windings are powered by three-phase AC, a rotating magnetic field with the same frequency as the AC current is generated, driving the rotor to rotate. In recent years, flat wire windings made of copper wire, known as hairpin windings, have become common. Compared to conventional windings with a circular cross section, flat wire (also known as rectangular wire) windings can carry higher currents and have better heat dissipation performance when operating electric machines at high power density and high efficiency.

[0003] To assemble the hairpin winding group, first, multiple rectangular copper wires are sequentially bent to form hairpin conductors. Next, multiple hairpin conductors are stacked radially and arranged in a ring shape circumferentially based on the winding wiring diagram. The open ends of these conductors are then inserted axially into slots in the stator core. The open ends of the hairpins are then twisted, cut flat, welded, and other processes to form the rectangular wire winding group. Summary of the Invention [Problem to be solved by the invention]

[0004] Existing hairpin conductor units are divided into hairpin (or U-shaped pin), I-shaped pin, X-shaped pin, and S-shaped winding types based on the structure. In addition, considering the complicated process of assembling the hairpin winding and the high requirements for molding precision, if the winding method can be simplified, the design difficulty can be greatly reduced.

[0005] The present inventor therefore believed that the above-mentioned shortcomings could be improved, and after extensive research, came up with the present invention, which effectively improves the above-mentioned problems through rational design.

[0006] SUMMARY OF THE PRESENT DISCLOSURE The present invention has been made in view of the above circumstances, and has an object to provide a modular hairpin winding group structure. [Means for solving the problem]

[0007] In order to solve the above problems, a modular hairpin winding group according to one aspect of the present invention is attached to a stator core and used to configure a winding group for one of three phases of a three-phase winding group, the winding group for one of the phases having at least one phase unit, and the modular hairpin winding group includes a plurality of rectangular wire conductors that are sequentially connected in series to form each of the phase units.

[0008] The stator core includes a yoke portion and a plurality of teeth arranged along the circumferential direction of the yoke portion to form N slots, and each of the slots is used to accommodate L+2 layers of rectangular wire conductors (N is a multiple of 12, and N and L are positive integers).

[0009] The rectangular wire conductor of each phase unit includes one first hairpin winding, one second hairpin winding, one third hairpin winding, and 2L fourth hairpin windings, and two conductors, and each of the first hairpin winding, the second hairpin winding, the third hairpin winding, and the fourth hairpin winding has a crown portion, two extension portions each having one end extended from both ends spaced apart from the crown portion, and two welded portions each formed by extending from the other ends of the extension portions.

[0010] The crown portion of the first hairpin winding spans across six slot pitches and the two extension portions of the first hairpin winding are disposed in a first layer of the slots.

[0011] The crown portion of the second hairpin winding spans across seven slot pitches, and the two extension portions of the second hairpin winding are disposed in the L+2th layer of the slots.

[0012] The crown portion of the third hairpin winding spans across five slot pitches, and the two extension portions of the third hairpin winding are disposed in the L+2th layer of the slots.

[0013] The crown portion of each of the fourth hairpin windings spans across five slot pitches, the two extensions of the fourth hairpin windings are disposed in layers 2 through L+1 of the slots, and the two extensions of the same fourth hairpin windings span across layers adjacent to the slots.

[0014] The two conductors each have a connection portion disposed in the first layer of the slot, and each connection portion is expanded outward to form a weld portion.

[0015] The two welded portions of the first hairpin winding are respectively connected to the welded portions of one of the two fourth hairpin windings in the second layer of the slot.

[0016] The welded portions of each of the two conductors are respectively connected to the welded portions of one of the two fourth hairpin windings in the second layer of the slot.

[0017] The two welded portions of the second hairpin winding are adjacent to each other and connected to the welded portion of one of the fourth hairpin windings in the L+1th layer of the slot.

[0018] The two welded portions of the third hairpin winding are adjacent to each other and connected to the welded portion of one of the fourth hairpin windings in the L+1th layer of the slot.

[0019] The welded portion and the extended portion of one of the remaining fourth hairpin windings are connected to the welded portion of another of the adjacent fourth hairpin windings having the same number of slot layers.

[0020] By wiring the conductors as described above, the hairpin windings of each phase unit are arranged along only a portion of the circumference of the stator core, and each phase unit is considered to be a single modular structure, simplifying the wiring design and reducing the difficulty of installation.

[0021] Furthermore, the connection portions of the two conductors are disposed in the n1th slot and the n1+6th slot, respectively (n1 is a positive integer); The two extensions of the first hairpin winding are disposed in the n1+1 slot and the n1+7 slot, respectively; The two extensions of the second hairpin winding are disposed in the n1+5th slot and the n1+12th slot, respectively; The two extensions of the third hairpin winding are disposed in the n1+6th slot and the n1+11th slot, respectively; The extension portion of one of the fourth hairpin windings is located in the n1th slot, the n1+1th slot, the n1+6th slot, or the n1+7th slot.

[0022] Further, two of the weld portions of the fourth hairpin winding are both curved toward the crown portion, one of the weld portions of the first hairpin winding is curved toward the crown portion and the other of the weld portions is curved away from the crown portion, one of the weld portions of the second hairpin winding is curved toward the crown portion and the other of the weld portions is curved away from the crown portion, one of the weld portions of the third hairpin winding is curved toward the crown portion and the other of the weld portions is curved away from the crown portion, and each of the weld portions spans 2.5 slot pitches at a distance from the crown portion.

[0023] Also, a stator core structure according to another aspect of the present invention includes the above-mentioned modular hairpin winding group structure for configuring at least one phase unit of a winding group of any one of three-phase winding groups.

[0024] At least the following points will become apparent from the following specification and drawings. [Brief description of the drawings]

[0025] [Figure 1] 1 is a partial external perspective view showing a stator structure of a three-phase motor according to an embodiment of the present invention; [Diagram 2] 1 is a partial external perspective view showing a stator structure of a three-phase motor according to an embodiment of the present invention; [Diagram 3] 1 is a partial external perspective view showing a stator structure of a three-phase motor according to an embodiment of the present invention; [Figure 4A] 1 is a schematic diagram of a hairpin winding unit according to an embodiment of the present invention; [Figure 4B] 1 is a schematic diagram of a hairpin winding unit according to an embodiment of the present invention; [Figure 4C] 1 is a schematic diagram of a hairpin winding unit according to an embodiment of the present invention; [Diagram 5] 1 is a schematic diagram of a hairpin winding unit according to an embodiment of the present invention; [Figure 6A] 1 is a schematic diagram showing a conductive wire according to an embodiment of the present invention; [Figure 6B] 1 is a schematic diagram showing a conductive wire according to an embodiment of the present invention; [Figure 7A] FIG. 2 is a schematic diagram showing the connection of each conductor of one phase unit of a winding group according to an embodiment of the present invention. [Figure 7B] FIG. 2 is a schematic diagram showing the connection of each conductor of one phase unit of a winding group according to an embodiment of the present invention. [Figure 7C] FIG. 2 is a schematic diagram showing the connection of each conductor of one phase unit of a winding group according to an embodiment of the present invention. [Figure 7D]FIG. 2 is a schematic diagram showing the connection of each conductor of one phase unit of a winding group according to an embodiment of the present invention. [Figure 8A] 2 is a wiring diagram showing a U-phase winding in accordance with one embodiment of the present invention. [Figure 8B] 2 is a wiring diagram showing a V-phase winding according to one embodiment of the present invention. FIG. [Figure 8C] 2 is a wiring diagram showing a W-phase winding in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiment, and various forms may be adopted as long as they fall within the technical scope of the present invention.

[0027] The motor structure according to the present invention includes an inner rotor and an outer stator, and the complete stator core structure is an annular structure, but in order to clearly distinguish the concept of the present invention, only a part of the stator core structure is shown in this embodiment. Figures 1 to 3 show a part of the stator core structure, which includes a stator core 100 and a hairpin winding group 200.

[0028] The stator core 100 is formed by stacking a plurality of core units along the axial direction, and each core unit includes an annular yoke portion 101 and a plurality of teeth 102 arranged along the circumferential direction of the yoke portion 101. Slots (6 to 18) expanding along the radial direction are formed between adjacent pairs of teeth 102. The hairpin winding group 200 includes a plurality of rectangular wire conductors arranged along the axial direction and inserted into the slots of the stator core 100.

[0029] In this embodiment, the stator core 100 is configured with N slots, and each slot is used to accommodate L+2 layers of rectangular wire conductors (N is a multiple of 12, and N and L are positive integers).

[0030] In this embodiment, the hairpin winding group 200 constitutes a first phase winding group, a second phase winding group, and a third phase winding group of a three-phase winding group, and each of the winding groups of any one phase has at least one phase unit 210 (see FIG. 7D). The phase units 210 of the first phase winding group, the second phase winding group, and the third phase winding group are installed so as to be sequentially and periodically arranged along the circumferential direction of the stator core 100.

[0031] In this embodiment, each of the phase winding groups has a plurality of phase units 210, which are equiangularly arranged around the stator core 100. In one embodiment, the phase units 210 are parallel branches, and in another embodiment, the phase units 210 of the same phase winding group are connected in series using a conductor. The welded portions B4 of the phase units 210 of the first phase winding group, the second phase winding group, and the third phase winding group may be connected using a neutral wiring 300. In another embodiment, each phase winding group may have only one phase unit 210, and three phase units 210 may be equiangularly arranged around the stator core 100.

[0032] All of the phase winding groups according to this embodiment are composed of one or more identical phase units 210, and the hairpin winding group 200 of each phase unit 210 is configured to be arranged along only a portion of the circumference of the stator core 100, and each phase unit is considered to be a single modular structure. This simplifies the wiring design and reduces the difficulty of installation.

[0033] In the following, the span (or slot pitch) refers to the distance that two extensions of the same conductor in the winding group of an electric machine span in the stator core, and is usually expressed by the number of slots in the stator core. For example, if two extensions are located in the n0+1th slot and the n0+6th slot, respectively (n0 is a positive integer), the distance between the extensions is defined as five slot pitches.

[0034] The crown portion in the following description is used to define the curved portion between two extensions of the same hairpin winding, and does not refer to the curved wire portion being crown shaped. The slot pitch described above is used to define the distance between both ends of the crown portion.

[0035] 4A, 4B, 4C, 5, 6A and 6B show the types of conductors used in each phase unit 210. FIG.

[0036] 4A, 4B and 4C respectively show a first hairpin winding U1, a second hairpin winding U2 and a third hairpin winding U3. All the hairpin windings have a crown portion C1, C2, C3 and two extension portions A1, A2, respectively, and one end is respectively extended from both ends of the crown portion, and two welding portions B1, B2 are respectively extended from the other ends of the extension portions A1, A2. The extension portions A1, A2 are assembled into a slot, and the welding portions B1, B2 are used to connect the welding portions B1, B2 of adjacent conductors to form a complete circuit. Considering the assembly between the corresponding conductors, the welding portions B1, B2 of each conductor may be curved with respect to the extension portions A1, A2.

[0037] The crown portions C1, C2, and C3 of the first hairpin winding U1, the second hairpin winding U2, and the third hairpin winding U3 straddle the slot pitches X, Y, and Z, respectively, where X=7, Y=5, and Z=6.

[0038] One of the welds B1, B2 of the first hairpin winding U1, the second hairpin winding U2, and the third hairpin winding U3 is curved toward the crown portions C1, C2, C3, and the other is curved away from the crown portions C1, C2, C3, in this embodiment, each of the welds spans a slot pitch of T at a distance from the crown portions, where T=2.5.

[0039] 5 shows a fourth hairpin winding U4, which also has a crown C4, two extensions A1, A2, and two welds B1, B2. The crown C4 spans across a slot pitch of Y, where Y=5, and the two welds B1, B2 are both curved toward the crown C4, and the two extensions A1, A2 of the same fourth hairpin winding U4 span across adjacent layers of the slot, which is different from the hairpin windings U1, U2, U3 described above. When multiple fourth hairpin windings U4 are all assembled into slots with the same serial number, the welds B1, B2 of all the fourth hairpin windings U4 are aligned in the same straight line.

[0040] 6A and 6B show conductors I1 and I2 having connection portions A3 and A4 assembled in slots, respectively, and both ends of each connection portion A3 and A4 are expanded outward to form welded portions B3 and B4. The welded portion B3 is adjacent to the welded portion B1 of the hairpin winding and is used to connect adjacent conductors of the phase unit 210. The other welded portion B4 is adjacent to the crown portions C1, C2, and C3 of the hairpin winding and is connected to another phase unit 210 of the same phase winding group via an external conductor or to a phase unit 210 of a different phase winding group via a neutral wiring 300.

[0041] 7A to 7D, each phase unit 210 according to this embodiment includes one first hairpin winding U1, one second hairpin winding U2, one third hairpin winding U3, 2L fourth hairpin windings U4, a conductor I1, and a conductor I2.

[0042] In the example of FIG. 7A, the two extensions A1, A2 of the first hairpin winding U1 are respectively arranged in the first layer of the slot.

[0043] In the example of FIG. 7D, the two extensions A1, A2 of the second hairpin winding U2 are respectively arranged in the L+2th layer of the slot.

[0044] In the example of FIG. 7D, the two extensions A1, A2 of the third hairpin winding U3 are respectively arranged in the L+2th layer of the slot.

[0045] In the example of Figs. 7B and 7C, the two extensions A1, A2 of the fourth hairpin winding U4 are arranged in the 2nd to L+1th layers of the slots.

[0046] In the example of FIG. 7A, the connection portions A3 and A4 of the conductor I1 and conductor I2 are disposed in the first layer of the slot.

[0047] When the connection portion A3 of the conductor I1 is arranged in the n1-th slot and the connection portion A4 of the conductor I2 is arranged in the n1+6-th slot (n1 is a positive integer), the connection method of the above-mentioned conductors is as follows: An extension portion A1 of the fourth hairpin winding U4 is located in the second layer, the n1 slot, and a welding portion B1 corresponding to the extension portion A1 (of the fourth hairpin winding U4) is interconnected with a welding portion B3 of the conductor I1; An extension portion A1 of the fourth hairpin winding U4 is located in the second layer, the n1+6th slot, and a welding portion B1 corresponding to the extension portion A1 (of the fourth hairpin winding U4) is interconnected with a welding portion B3 of the conductor I2.

[0048] The two extensions A1, A2 of the first hairpin winding U1 are located in the n1+1th slot and the n1+7th slot, respectively.

[0049] An extension portion A1 of the fourth hairpin winding U4 is located in the second layer, the n1+1th slot, and a welding portion B1 corresponding to the extension portion A1 (of the fourth hairpin winding U4) is interconnected with the welding portion B1 of the first hairpin winding U1.

[0050] An extension portion A1 of the fourth hairpin winding U4 is located in the second layer, the n1+7th slot, and a welding portion B1 corresponding to the extension portion A1 (of the fourth hairpin winding U4) is interconnected with a welding portion B2 of the first hairpin winding U1.

[0051] The two extensions A1, A2 of the second hairpin winding U2 are located in the n1+5th slot and the n1+12th slot, respectively.

[0052] One extension portion A2 of the fourth hairpin winding U4 is located in the L+1th layer, the n1+5th slot, and the weld portion B2 corresponding to the extension portion A1 (of the fourth hairpin winding U4) is interconnected with the weld portion B1 of the second hairpin winding U2.

[0053] One extension portion A2 of the fourth hairpin winding U4 is located in the L+1th layer, the n1+12th slot, and the welding portion B2 corresponding to the extension portion A1 (of the fourth hairpin winding U4) is interconnected with the welding portion B2 of the second hairpin winding U2.

[0054] The two extension parts A1, A2 of the third hairpin winding U3 are located in the n1+6th slot and the n1+11th slot, respectively.

[0055] An extension portion A2 of one of the fourth hairpin windings U4 is located in the L+1th layer, the n1+6th slot, and a welding portion B2 corresponding to the extension portion A2 (of the fourth hairpin winding U4) is interconnected with the welding portion B1 of the third hairpin winding U3.

[0056] An extension portion A2 of one of the fourth hairpin windings U4 is located in the L+1th layer, the n1+11th slot, and a welding portion B2 corresponding to the extension portion A2 (of the fourth hairpin winding U4) is interconnected with the welding portion B2 of the third hairpin winding U3.

[0057] The remaining fourth hairpin windings U4 are connected in such a way that the extension portion A1 of one of the fourth hairpin windings U4 is connected to the other welding portion B1 of another fourth hairpin winding U4 located in an adjacent layer of the same slot, thereby forming one phase unit 210 by sequentially connecting all the conductors in series.

[0058] 8A to 8C, the wiring diagrams of the U-phase winding group, the V-phase winding group, and the W-phase winding group of the three-phase motor stator are shown based on the above-mentioned embodiment. The wiring diagrams between the U-phase winding group, the V-phase winding group, and the W-phase winding group are basically the same, but are installed to be offset and arranged along the circumferential direction of the stator core 100. Each of the phase units 210 is connected in series in sequence to form a complete circuit surrounding the stator core.

[0059] In this embodiment, each phase winding group has four phase units 210, and each slot is provided with eight layers of extensions, ie, N=48, L=6.

[0060] 7A to 7D, the tangency method of phase unit 210 installed in slots 6 to 18 of the U-phase winding group will be described as an example. In the figures, solid lines indicate the actual conductors, and dashed lines indicate the tangency method of the welded parts. Connection portion A3 of conductor I1 is located in the 18th slot of the first layer and serves as a current input end. Connection portion A4 of conductor I1 is located in the 12th slot of the first layer and serves as a current output end. Below, the tangency method of each conductor will be described based on the actual situation. The extension portion A1 of the No. 1 hairpin winding is located in the 13th slot of the second layer, and the extension portion A2 is located in the 18th slot of the third layer. The extension portion A1 of the No. 2 hairpin winding is located in the 13th slot of the fourth layer, and the extension portion A2 is located in the 18th slot of the fifth layer. The extension portion A1 of the No. 3 hairpin winding is located in the 13th slot of the 6th layer, and the extension portion A2 is located in the 18th slot of the 7th layer. The extension portion A1 of the No. 4 hairpin winding is located in the 13th slot of the 8th layer, and the extension portion A2 is located in the 6th slot of the 8th layer. The extension portion A2 of the No. 5 hairpin winding is located in the 11th slot of the 7th layer, and the extension portion A1 is located in the 6th slot of the 6th layer. The extension portion A2 of the No. 6 hairpin winding is located in the 11th slot of the 5th layer, and the extension portion A1 is located in the 6th slot of the 4th layer. The extension portion A2 of the No. 7 hairpin winding is located in the 11th slot of the third layer, and the extension portion A1 is located in the 6th slot of the second layer. The extension portion A2 of the No. 8 hairpin winding is located in the 11th slot of the first layer, and the extension portion A1 is located in the 7th slot of the first layer. The extension portion A1 of the No. 9 hairpin winding is located in the 17th slot of the second layer, and the extension portion A2 is located in the 12th slot of the third layer. The extension portion A1 of the No. 10 hairpin winding is located in the 17th slot of the fourth layer, and the extension portion A2 is located in the 12th slot of the fifth layer. The extension portion A1 of the No. 11 hairpin winding is located in the 17th slot of the 6th layer, and the extension portion A2 is located in the 12th slot of the 7th layer. The extension portion A1 of the No. 12 hairpin winding is located in the 12th slot of the 8th layer, and the extension portion A2 is located in the 7th slot of the 8th layer. The extension portion A2 of the No. 13 hairpin winding is located in the 12th slot of the 7th layer, and the extension portion A1 is located in the 7th slot of the 6th layer. The extension portion A2 of the No. 14 hairpin winding is located in the 12th slot of the fifth layer, and the extension portion A1 is located in the 7th slot of the fourth layer. The extension portion A2 of the No. 15 hairpin winding is located in the 12th slot of the third layer, and the extension portion A1 is located in the 7th slot of the second layer.

[0061] The connection portion A4 of the conductor I2 is located in the 12th slot of the first layer and serves as a current output end.

[0062] The No. 4 hairpin winding is the second hairpin winding U2, the No. 8 hairpin winding is the first hairpin winding U1, the No. 12 hairpin winding is the third hairpin winding U3, and the remaining hairpin winding is the fourth hairpin winding U4.

[0063] In this embodiment, the first layer is adjacent to the inner surface of the stator core, and the eighth layer is adjacent to the outer surface of the stator core, but the first layer and the eighth layer may also be defined as the inner surface and the outer surface of the stator core, respectively.

[0064] In other embodiments, the current inputs and outputs may be swapped. The wiring may be changed from counterclockwise to clockwise.

[0065] The present invention may be embodied in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as being limited. The scope of the present invention is defined by the scope of the utility model registration claims and is not limited by the text of the specification. Furthermore, all modifications and changes within the scope of the utility model registration claims are within the scope of the present invention. [Explanation of symbols]

[0066] 6 to 18 slots 100 stator core 101 York 102 Teeth 200 Hairpin Winding Group 210 Phase Unit 300 Neutral wire wiring U1 Hairpin winding U2 Hairpin winding U3 Hairpin Winding U4 Hairpin Winding I1, I2 conductors A1 Extension A2 Extension A3 Connection part A4 Connection part B1 Welded part B2 Welded part B3 Welded part B4 Welded part C1 Crown part C2 Crown part C3 Crown part C4 Crown part X Slot Pitch Y Slot Pitch Z Slot Pitch T-slot pitch

Claims

1. A modular hairpin winding group is attached to a stator core to form a winding group of any one of three-phase winding groups, the winding group of any one of the three-phase winding groups having at least one phase unit, the modular hairpin winding group including a plurality of rectangular wire conductors connected in series to form each of the phase units; The stator core includes a yoke portion and a plurality of teeth arranged along the circumferential direction of the yoke portion to form N slots, each of the slots being used to accommodate L+2 layers of rectangular wire conductors (N is a multiple of 12, and N and L are positive integers); The rectangular wire conductor of each of the phase units includes one first hairpin winding, one second hairpin winding, one third hairpin winding, and 2L fourth hairpin windings, and two conductors, and each of the first hairpin winding, the second hairpin winding, the third hairpin winding, and the fourth hairpin winding has a crown portion, two extension portions each having one end extended from both ends spaced apart from the crown portion, and two welded portions each formed by extending from the other ends of the extension portions, The crown portion of the first hairpin winding spans across six slot pitches, and the two extension portions of the first hairpin winding are disposed in a first layer of the slots; The crown portion of the second hairpin winding spans across seven slot pitches, and the two extension portions of the second hairpin winding are disposed in the L+2 layer of the slot; The crown portion of the third hairpin winding spans across five slot pitches, and the two extension portions of the third hairpin winding are disposed in an L+2 layer of the slots; The crown portion of each of the fourth hairpin windings spans across five slot pitches, the two extensions of the fourth hairpin windings are disposed in layers 2 to L+1 of the slots, and the two extensions of the same fourth hairpin winding span across layers adjacent to the slots; The two conductive wires each have a connection portion disposed in the first layer of the slot, and each of the connection portions is expanded outward to form a weld portion; The two welded portions of the first hairpin winding are respectively connected to one welded portion of the two fourth hairpin windings of the second layer of the slot; the welded portions of each of the two conductors are respectively connected to the welded portions of one of the two fourth hairpin windings of the second layer of the slot; two welded portions of the second hairpin winding are respectively adjacent to each other and connected to one welded portion of the fourth hairpin winding in the L+1th layer of the slot; two welded portions of the third hairpin winding are respectively adjacent to each other and connected to one welded portion of the fourth hairpin winding in the L+1th layer of the slot; the welded portion and the extended portion of one of the remaining fourth hairpin windings are connected to the other welded portion of the adjacent fourth hairpin winding having the same number of slot layers.

2. The connection portions of the two conductors are respectively arranged in the n1th slot and the n1+6th slot (n1 is a positive integer); The two extensions of the first hairpin winding are disposed in the n1+1 slot and the n1+7 slot, respectively; The two extensions of the second hairpin winding are disposed in the n1+5 slot and the n1+12 slot, respectively; The two extensions of the third hairpin winding are disposed in the n1+6 slot and the n1+11 slot, respectively; 2. The modular hairpin winding group of claim 1, wherein the extension portion of one of the fourth hairpin windings is located in the n1 slot, the n1+1 slot, the n1+6 slot, or the n1+7 slot.

3. The two welded portions of the fourth hairpin winding are both curved toward the crown portion, the welded portion of one of the first hairpin windings is curved toward the crown portion and the welded portion of the other of the first hairpin windings is curved away from the crown portion; the welded portion of one of the second hairpin windings is curved toward the crown portion and the welded portion of the other of the second hairpin windings is curved away from the crown portion; the welded portion of one of the third hairpin windings is curved toward the crown portion and the welded portion of the other of the third hairpin windings is curved away from the crown portion; 2. The modular hairpin winding group of claim 1, wherein each said weld is spaced from said crown portion across 2.5 slot pitches.

4. A stator core structure comprising the modular hairpin winding group according to any one of claims 1 to 3 for constituting at least one phase unit of a winding group of any one phase of a three-phase winding group.

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