Stator assembly and motor

Abstract

The present invention provides a stator assembly and a motor, specifically relating to the field of motor technology. The stator assembly includes a stator core and a stator winding. The stator core is provided with a plurality of slots for winding wiring along the circumferential direction. The stator winding includes L layers of flat wire conductors embedded in the plurality of slots, where L is an even number. The L layers of flat wire conductors include a plurality of stacked coil groups, a plurality of first wave-wound coils, and a plurality of second wave-wound coils. The plurality of stacked coil groups are connected by the first wave-wound coils and the second wave-wound coils and are distributed in a ring-shaped chain in the circumferential direction of the core. The stator assembly of the present invention can effectively avoid stator winding circulating current, reduce losses, increase slot fill rate, and thereby improve motor efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a stator assembly and a motor. Background Art

[0002] With the rapid development of new energy vehicle technology, the performance requirements for automotive drive motors are becoming increasingly higher. The main development trends of new energy vehicle motors are miniaturization and high speed, and miniaturization and high speed will inevitably require a significant improvement in motor efficiency.

[0003] Compared to round wire motors, flat wire motors can improve the slot fill rate of the motor. This increase in slot fill rate means that more copper wire can be packed into the motor while maintaining the same space, generating a stronger magnetic field strength and increasing power density. Therefore, more and more flat wire motors are being used in new energy vehicle drive systems. Existing flat wire motors often use short-torque windings to weaken the magnetic potential harmonics of the windings. For example, CN201520265436.3 - A motor and its stator uses short-pitch windings, and CN202010193400.4 - Flat wire continuous wave windings. Although the flat wire continuous wave windings in the stator and motor use full-pitch windings, the stator and motor use staggered windings, making them equivalent to a set of double-layer short-pitch windings. As a result, the conductors in a slot belong to different phases. To ensure insulation reliability, it is necessary to add interlayer insulating paper, which reduces the slot fill rate of the winding and reduces the efficiency of the motor. Summary of the Invention

[0004] In view of the above shortcomings of the prior art, the present invention provides a stator assembly and a motor to improve the problem of circulating current in the stator winding and the problem of reducing the slot fill rate due to interlayer insulation paper.

[0005] To achieve the above-mentioned and other related objectives, the present invention provides a stator assembly, comprising a stator core and a stator winding, wherein the stator core is provided with a plurality of slots for winding wiring along the circumferential direction; the stator winding comprises L layers of flat wire conductors embedded in the slots, where L is an even number; the L layers of flat wire conductors comprise a plurality of stacked coil groups, a plurality of first wave-wound coils, and a plurality of second wave-wound coils, wherein the plurality of stacked coil groups are connected by the plurality of first wave-wound coils and the plurality of second wave-wound coils and are distributed in a ring-shaped chain in the circumferential direction of the core.

[0006] In one example of the present invention, in each branch of each phase of the stator winding, the stacked coil group is connected end to end through the first wave-wound coil and advances one circle along the circumferential direction of the stator core. Then, it is connected to the next stacked coil group through the second wave-wound coil and continues to advance one circle in the same winding method, thereby forming the branch.

[0007] In an example of the present invention, the flat wire conductors of each branch in the slot are symmetrical, and all the flat wire conductors in the same slot belong to the winding of the same phase.

[0008] In one example of the present invention, the stacked coil group includes a plurality of stacked coils, each stacked coil including a bent section, two straight sections, and two twisted sections. The two straight sections are respectively connected to the two ends of the bent section, and the two twisted sections are respectively connected to the two straight sections. The two twisted sections are respectively deflected and bent along the circumferential direction of the stator core, with the deflection directions being opposite and close to each other.

[0009] In an example of the present invention, the number of pole pairs of the motor is p, the number of slots is Q, and the pole pitch y=Q / (2p). Then, the span of the stacked coil is y, and the two straight segments of the stacked coil are located in adjacent conductor layers.

[0010] In an example of the present invention, the span of the first wave-wound coil is y, and the first wave-wound coil is a cross-layer coil, which is used to connect the flat wire conductors of the first layer and the Lth layer.

[0011] In an example of the present invention, the span of the second wave wound coil is y+1 or y-1, and the second wave wound coil is a cross-layer coil, used to connect the flat wire conductors of the first layer and the Lth layer.

[0012] In an example of the present invention, the first wave-wound coil and the second wave-wound coil have the same structure, both including a bent section, two straight sections and two twisted sections, the two straight sections are respectively connected to the two ends of the bent section, the two twisted sections are respectively connected to the two straight sections, and the two twisted sections are respectively deflected and bent along the circumferential direction of the stator core, with the deflection directions being opposite and away from each other.

[0013] In an example of the present invention, each phase of the stator winding includes 1 or an even number greater than or equal to 2 branches.

[0014] In an example of the present invention, when each phase of the stator winding includes one branch, the input end and the output end of the branch are located at the innermost layer of the winding layer, and the other is located at the outermost layer; when each phase of the stator winding includes an even number of branches greater than or equal to 2, the input end of half of the branches is located at the innermost layer of the winding layer, and the output end is located at the outermost layer, and the input end of the remaining branches is located at the outermost layer of the winding layer, and the output end is located at the innermost layer.

[0015] Another aspect of the present invention provides a motor including the stator assembly.

[0016] The stator winding of the stator assembly of the present invention connects multiple stacked coil groups end to end through a first wave-wound coil and a second wave-wound coil so that they are distributed in a ring-shaped chain along the circumferential direction of the stator core. This winding method makes the flat wire conductors of each branch in the slot body completely symmetrical, and all the flat wire conductors in the same slot body belong to the winding of the same phase, which can avoid stator winding circulation current, reduce losses, and improve motor efficiency; eliminate interlayer insulation paper, increase the slot fill rate of the flat wire conductor, and thus improve motor efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 Schematic diagram of the structure of the stator assembly of the present invention;

[0019] Figure 2 FIG1 is an expanded view of the winding of phase A in the stator winding of the stator assembly in one embodiment of the present invention;

[0020] Figure 3 A schematic structural diagram of a stacked coil of a stator assembly according to an embodiment of the present invention;

[0021] Figure 4 Schematic diagram of the structure of the first wave wound coil of the stator assembly in one embodiment of the present invention;

[0022] Figure 5 Schematic diagram of the structure of the second wave wound coil of the stator assembly in one embodiment of the present invention;

[0023] Figure 6 Schematic diagram of the structure of the winding lead wire of the stator assembly in one embodiment of the present invention;

[0024] Figure 7 A schematic diagram of the partial distribution of flat wire conductors within a slot of a stator assembly in one embodiment of the present invention;

[0025] Figure 8 Schematic diagram of a stator assembly of the present invention in which two branches of the A-phase winding are connected in series to form a parallel branch in one embodiment;

[0026] Figure 9 FIG. 1 is a schematic diagram of a stator assembly of the present invention in which two branches of the A-phase winding are connected in parallel to form two parallel branches in one embodiment.

[0027] Component number description

[0028] 100. Stator assembly; 110. Stator core; 111. Slot body; 120. Stator winding; 1201. U-Pin insertion end; 1202. Welding end; 121. Stacked coil; 1211. First U-shaped bend section; 1212. First straight section; 1213. First twist section; 122. First wave-wound coil; 1221. Second U-shaped bend section; 1222. Second straight section; 1223. Second twist section; 123. Second wave-wound coil; 1231. Third U-shaped bend section; 1232. Third straight section; 1233. Third twist section; 124. Lead wire; 1241. Fourth bend section; 1242. Fourth straight section; 1243. Fourth twist section. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0030] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0031] See also Figures 1 to 9 The present invention provides a stator assembly and a motor to improve the circulating current problem of the stator winding and the problem of reducing the slot fill rate by the interlayer insulation paper.

[0032] See also Figure 1 The stator assembly 100 of the present invention includes a stator core 110 and a stator winding 120. The stator core 110 is provided with a plurality of slots 111 for winding wiring. The stator winding 120 includes L layers of flat wire conductors embedded in the slots 111. The L layers of flat wire conductors include a plurality of stacked coil groups, a plurality of first wave-wound coils 122, and a plurality of second wave-wound coils 123. The plurality of stacked coil groups are connected by the plurality of first wave-wound coils 122 and the plurality of second wave-wound coils 123 and are distributed in a ring-shaped chain in the circumferential direction of the stator core.

[0033] See also Figure 1 Specifically, the stator core 110 includes a main body that is generally cylindrical, and a plurality of slots 111 are arranged along the inner circumference of the cylindrical main body. The slots 111 are radially open inward. The stator winding 120 adopts a flat wire hairpin winding, which includes a U-Pin insertion end 1201 and a welding end 1202. In this embodiment, the upward end is the U-Pin insertion end 1201, and the downward end is the welding end 1202.

[0034] See also Figure 1 and Figure 2 The stator winding 120 is a three-phase winding. Specifically, in each branch of each phase of the stator winding 120, multiple stacked coil groups are connected end-to-end via a first wave-wound coil 122, then advance one circle along the circumference of the stator core 110. Then, they are connected to the next stacked coil group via a second wave-wound coil 123, and continue one circle in the same manner, thus forming a complete branch. Each branch of each phase of the stator winding 120 employs the aforementioned winding method, differing in that the slot numbers of the slots 111 where the inlet and outlet terminals of each phase are located are different. For example, if the stator winding 120 is a three-phase winding, the three phases of the three-phase winding are defined as phase A, phase B, and phase C, respectively. The inlet terminal of the phase A winding is slot number 27, the inlet terminal of the phase B winding can be slot number 31, and the inlet terminal of the phase C winding can be slot number 35. This winding method makes the flat wire conductors of each branch in the slot body 111 completely symmetrical, and all flat wire conductors in the same slot body 111 belong to the same phase winding. No insulating paper is required between layers, which improves the slot fill rate of the flat copper wire and thus improves the efficiency of the motor.

[0035] In the present invention, each phase of the stator winding 120 includes 1 or an even number of branches greater than or equal to 2. When each phase of the stator winding 120 includes 1 branch, the input end and the output end of the branch are located at the innermost layer (first layer) of the winding layer, and the other is located at the outermost layer (Lth layer); when each phase of the stator winding 120 includes an even number of branches greater than or equal to 2, the input ends of half of the branches are located at the innermost layer of the winding layer, and the output ends are located at the outermost layer, and the input ends of the remaining branches are located at the outermost layer of the winding layer, and the output ends are located at the innermost layer.

[0036] See also Figure 1 and Figure 2The stacked coil group includes a plurality of stacked coils 121 arranged in layers. In one embodiment, the number of pole pairs of the motor is p, the number of slots is Q, and the pole pitch y=Q / (2p). Then, the span of the stacked coil 121 is y, and both sides of the stacked coil 121 are located in adjacent conductor layers. The span of the first wave-wound coil 122 is y, and is used to connect the first layer and the Lth layer coils. The span of the second wave-wound coil 123 is y+1 or y-1, and is used to connect the first layer and the Lth layer coils. Those skilled in the art can understand that one side of the stacked coil 121 is located in the slot body 111 with slot number x, and the other side is located in the slot body 111 with slot number (x±y); the first wave-wound coil 122 is used to connect adjacent stacked coil groups, one end of which is located in the slot body 111 with slot number (x±y), and the other end is located in the slot body 111 with slot number (x±y±y); the second wave-wound coil 123 is used to connect the stacked coil group at the end of the first circumferential layer and the stacked coil group at the starting end of the second circumferential layer.

[0037] See also Figure 1 and Figure 3 In one embodiment, the lapped coil 121 includes a bent section at the head, a straight section connected to the bent section, and a twist section connected to the straight section, which are respectively denoted as a first bent section 1211, a first straight section 1212, and a first twist section 1213. The two ends of the first bent section 1211 are each connected to a first straight section 1212, and the two first straight sections 1212 are parallel to each other. The other ends of the two first straight sections 1212 are each connected to a first twist section 1213. The two first twist sections 1213 are respectively deflected and bent along the circumferential direction of the iron core, and the deflection directions are opposite and close to each other, that is, the two first twist sections 1213 are relatively deflected and bent toward the middle of the coil. The first bent section 1211 of the lap coil 121 is formed using a mold and inserted from the insertion end 1201 into the slot 111 of the stator core 110. The first straight section 1212 is located within the slot 111. The two first twisted sections 1213 extend from the slot 111 and deflect in opposite directions around the core circumference before being welded together at the welding ends. The multiple lap coils 121 within the lap coil assembly are welded together at the welding ends.

[0038] See also Figure 4The first wave-wound coil 122 is a U-shaped coil, comprising a bend, a straight segment connected to the bend, and a twist segment connected to the straight segment, denoted as a second bend segment 1221, a second straight segment 1222, and a second twist segment 1223, respectively. The second bend segment 1221 is connected to a second straight segment 1222 at each end, and the two second straight segments 1222 are parallel to each other. The other ends of the two second straight segments 1222 are connected to a second twist segment 1223, and the two second twist segments 1223 deflect along the circumference of the core in opposite directions and away from each other. One twist segment of the first wave-wound coil 122 is located in the first layer of the winding, and the other twist segment is located in the Lth layer of the winding. Therefore, the first wave-wound coil 122 is a cross-layer coil.

[0039] See also Figure 5 The second wave-wound coil 123 has the same structure as the first wave-wound coil 122, with a span of y+1 or y-1. It also includes a bend, a straight segment, and a twist segment, denoted as a third bend segment 1231, a third straight segment 1232, and a third twist segment 1233, respectively. The ends of the third bend segment 1231 are each connected to a third straight segment 1232, and the two third straight segments 1232 are parallel to each other. The other ends of the two third straight segments 1232 are each connected to a third twist segment 1233. The two third twist segments 1233 deflect along the circumference of the core, deflecting in opposite directions and moving away from each other. One third twist segment 1233 of the second wave-wound coil 123 is located in the first layer of the winding, and the other third twist segment 1233 is located in the Lth layer of the winding. Therefore, the second wave-wound coil 123 is a cross-layer coil.

[0040] See also Figure 6 Lead wire 124 is a semi-U-shaped coil, comprising a bend, a straight segment, and a twist segment, designated as fourth bend segment 1241, fourth straight segment 1242, and fourth twist segment 1243, respectively. Fourth bend segment 1241, fourth straight segment 1242, and fourth twist segment 1243 are sequentially connected. Preferably, lead wire 124 for each phase of stator winding 120 is located at insertion end 1201 to facilitate welding and coating at welding end 1202, thereby improving production efficiency.

[0041] The following takes a three-phase winding as an example to specifically describe the winding method of the present invention. In this embodiment, the three phases are defined as phase A, phase B, and phase C, respectively. An example is given with 8 poles, 48 slots, 6 layers of flat wire conductors in each slot, and 2 branches per pole and per phase. The number of slots Q = 48, the number of conductor layers L = 6, the number of pole pairs P = 4, the pole pitch y = Q / (2p) = 6, the span of the stacked coil 121 is 6, the span of the first wave-wound coil 122 is 6, and the span of the second wave-wound coil is 7 or 5.

[0042] In order to express the wiring of the present invention more clearly, Figure 2The winding expansion diagram only shows the winding of the A-phase coil group and does not include the B-phase and C-phase coil groups. The B-phase and C-phase coil groups are wound in the same manner as the A-phase coil group, differing only in the slot numbers where the incoming and outgoing wires are located. For example, the incoming wire of the A-phase winding is slot 27, while the incoming wire of the B-phase winding can be slot 31, and the incoming wire of the C-phase winding can be slot 35. Phase A consists of a first branch A1X1 and a second branch A2X2, where A1 and A2 are the incoming wires of the winding, and X1 and X2 are the outgoing wires. Figure 2 Each slot body has 6 layers, 5 layers, 4 layers, 3 layers, 2 layers, and 1 layer from left to right. The stacked coil group includes a first stacked coil, a second stacked coil, and a third stacked coil.

[0043] The specific winding method of the A-phase winding is as follows: the first branch of the A-phase winding enters from slot body No. 27, the first stacked coil of the first stacked coil group enters from the 6th layer of slot body No. 27, and comes out from the 5th layer of slot body No. 33; the second stacked coil enters from the 4th layer of slot body No. 27, and comes out from the 3rd layer of slot body No. 33; the third stacked coil enters from the 2nd layer of slot body No. 27, and comes out from the 1st layer of slot body No. 33, the first stacked coil, the second stacked coil and the third stacked coil are connected by welding at the welding end 1202; then the first wave-wound coil is connected to the flat wire conductor in slot body No. 33, a twist section of the first wave-wound coil is connected to the first layer of flat wire conductor in slot body No. 33, and the other end crosses 6 slots forward along the circumferential direction of the stator core to enter slot body No. 39, and the second stacked coil group is wound in slot body No. 39 and slot body No. 45. The winding rule is the same as that of the first stacked coil group, and the other twist section of the first wave-wound coil is connected to the flat wire conductor in slot body No. 33. The sixth layer of flat wire conductor in slot body 39 is connected; and the third stacked coil group is placed in slot body 3 and slot body 9, and the fourth stacked coil group is wound in slot body 15 and slot body 21, and wound one circle; then it is connected to the second circle through the second wave wound coil, and one twist section of the second wave wound coil is connected to the first layer of flat wire conductor in slot body 21, and the other end spans 7 slots along the circumferential direction of the stator core to slot body 28, and in slot body 28 Continue to wind the fifth stacked coil group in slot body No. 34, the other twist section of the second wave wound coil and the sixth layer of flat wire conductor in slot body No. 28, and then repeat the winding method of the first circle to wind the sixth stacked coil group in slot body No. 40 and slot body No. 46, the seventh stacked coil group in slot body No. 4 and slot body No. 10, and the eighth stacked coil group in slot body No. 16 and slot body No. 22. The second circle winding is completed to form the first branch A1X1.

[0044] The second branch enters from the first layer of slot body No. 27 and is wound in sequence along the opposite direction of the first branch, that is, the first stacked coil of the first stacked coil group enters from the first layer of slot body No. 27 and comes out from the second layer of slot body No. 21; the second stacked coil enters from the third layer of slot body No. 27 and comes out from the fourth layer of slot body No. 21; the third stacked coil enters from the fifth layer of slot body No. 27 and comes out from the sixth layer of slot body No. 21. The first stacked coil, the second stacked coil and the third stacked coil are connected by welding at the welding end 1202; then the second stacked coil group is wound on slot body No. 15 and slot body No. 9, the third stacked coil group is wound on slot body No. 3 and slot body No. 45, and the fourth stacked coil group is wound on slot body No. 39 and slot body No. 33. The winding method is the same as that of the first stacked coil group. The first stacked coil group, the second stacked coil group and the second stacked coil group are connected by welding at the welding end 1202. The winding coil group, the third stacked coil group and the fourth stacked coil group are connected end to end through the first wave-wound coil 122 to complete the winding of the first circle; then they are connected to the second circle through the second wave-wound coil 123. A twist section of the second wave-wound coil 123 is connected to the sixth layer of flat wire conductor in the 33rd slot, and the other end spans 5 slots along the circumferential direction of the stator core to the 28th slot to start the winding of the second circle. The winding method of the second circle is the same as the winding method of the first circle, that is, the fifth stacked coil group is wound in the 28th slot and the 22nd slot, the sixth stacked coil group is wound in the 16th slot and the 10th slot, the seventh stacked coil group is wound in the 4th slot and the 46th slot, and the eighth stacked coil group is wound in the 40th slot and the 34th slot. The winding ends at the 6th layer of the 34th slot, and the second circle is wound to form the second branch A2X2.

[0045] The winding path of the first branch A1X1 of the A-phase winding is as follows:

[0046] A1->27(6)->33(5)->27(4)->33(3)->27(2)->33(1)->39(6)->45(5)->39(4)

[0047] ->45(3)->39(2)->45(1)->3(6)->9(5)->3(4)->9(3)->3(2)->9(1)->15(6)->2 1(5)->15(4)->21(3)->15(2)->21(1)->28(6)->34(5)->28(4)->34(3)->28(2) ->34(1)->40(6)->46(5)->40(4)->46(3)->40(2)->46(1)->4(6)->10(5)->4(4 )->10(3)->4(2)->10(1)->16(6)->22(5)->16(4)->22(3)->16(2)->22(1)->X1

[0048] The winding path of the second branch A2X2 of the A-phase winding is as follows:

[0049] A2->27(1)->21(2)->27(3)->21(4)->27(5)->21(6)->15(1)->9(2)->15(3)

[0050] ->9(4)->15(5)->9(6)->3(1)->45(2)->3(3)->45(4)->3(5)->45(6)->39(1)-> 33(2)->39(3)->33(4)->39(5)->33(6)->28(1)->22(2)->28(3)->22(4)->28(5 )->22(6)->16(1)->10(2)->16(3)->10(4)->16(5)->10(6)->4(1)->46(2)->4( 3)->46(4)->4(5)->46(6)->40(1)->34(2)->40(3)->34(4)->40(5)->34(6)->X2

[0051] The numbers outside the brackets represent the slot numbers, and the numbers inside the brackets represent the layer numbers.

[0052] After winding of phase A is completed, phase B and phase C are wound in the same way. The incoming line end of phase B is slot body 31, and the incoming line end of phase C is slot body 35. After winding is completed, the distribution of windings in the slot body under one pole is as follows Figure 7 As shown, the conductors in each slot belong to the same phase, the interlayer insulation paper is eliminated, the slot fill rate of the winding is improved, the resistance of the winding is reduced, the copper loss of the motor is reduced, and the efficiency of the motor is improved.

[0053] The present invention improves the manufacturing efficiency of the stator winding by forming, inserting and welding a stacked coil, a cross-layer coil (a first wave-wound coil and a second wave-wound coil) and a semi-U-shaped coil (a lead wire) to form a complete branch.

[0054] See also Figure 8 and Figure 9 , the two branches A1X1 and A2X2 of phase A can be connected in series to form a parallel branch, that is, the outlet end of the first branch is connected to the incoming end of the second branch; or they can be connected in parallel to form two parallel branches, such as Figure 9 A star connection is shown, but a delta connection may also be used in other embodiments.

[0055] On the other hand, the present invention also provides a motor, which includes the stator assembly of the present invention. The stator assembly of the present invention is used to avoid circulating current, reduce losses, and improve motor efficiency through reasonable winding wiring; the lead wires of each phase of the stator winding are set at the plug-in end, which facilitates unified twisting, welding and coating of the welding end, thereby improving production efficiency.

[0056] It should be noted that the structures of the stator and the motor are not described in detail in the present invention and can be achieved through conventional technical means, which will not be described in detail here.

[0057] The stator assembly of the present invention utilizes rational winding routing to ensure complete symmetry of the conductors within each slot, with conductors within the same slot belonging to the same phase winding. This prevents circulating currents, reduces losses, and improves the motor's power density and efficiency. Furthermore, the interlayer insulation paper can be eliminated, increasing the slot fill rate and thus improving motor efficiency. Therefore, the present invention effectively overcomes several practical problems of the prior art and offers significant practical value and practical implications.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A stator assembly, characterized in that: include: A stator core having a plurality of slots for winding wiring arranged along the circumferential direction; The stator winding includes L layers of flat wire conductors embedded in the plurality of slots, where L is an even number; The L-layer flat wire conductor includes a plurality of stacked coil groups, a plurality of first wave coils, and a plurality of second wave coils, wherein the plurality of stacked coil groups are connected by the plurality of first wave coils and the plurality of second wave coils and are distributed in a ring-shaped chain in the circumferential direction of the stator core; The first wave-wound coil is used to connect adjacent stacked coil groups, and the span of the first wave-wound coil is y. The second wave-wound coil is used to connect the stacked coil group at the end of the first circumferential layer and the stacked coil group at the starting end of the second circumferential layer. The span of the second wave-wound coil is y+1 or y-1, where y represents the pole pitch of the motor. In each branch of each phase of the stator winding, the stacked coil group is connected end to end through the first wave-wound coil and advances one circle along the circumferential direction of the stator core. Then, it is connected to the next stacked coil group through the second wave-wound coil and continues to advance one circle in the same winding method, thereby forming the branch.

2. The stator assembly according to claim 1, characterized in that The flat wire conductors of each branch in the slot are symmetrical, and all the flat wire conductors in the same slot belong to the winding of the same phase.

3. The stator assembly according to claim 1, characterized in that The stacked coil group includes a plurality of stacked coils, each stacked coil including a bent section, two straight sections, and two twisted sections. The two straight sections are respectively connected to the two ends of the bent section, and the two twisted sections are respectively connected to the two straight sections. The two twisted sections are respectively deflected and bent along the circumferential direction of the stator core, with the deflection directions being opposite and close to each other.

4. The stator assembly according to claim 3, characterized in that The number of pole pairs of the motor is p, the number of slots is Q, and the pole pitch y=Q / (2p). Then, the span of the stacked coil is y, and the two straight segments of the stacked coil are located in adjacent flat wire conductor layers.

5. The stator assembly according to claim 4, characterized in that The first wave-wound coil is a cross-layer coil, which is used to connect the flat wire conductors of the first layer and the Lth layer.

6. The stator assembly according to claim 5, characterized in that The second wave wound coil is a cross-layer coil, and is used to connect the flat wire conductors of the first layer and the Lth layer.

7. The stator assembly according to claim 1, characterized in that The first wave-wound coil and the second wave-wound coil have the same structure, both including a bent section, two straight sections and two twisted sections. The two straight sections are respectively connected to the two ends of the bent section, and the two twisted sections are respectively connected to the two straight sections. The two twisted sections are respectively deflected and bent along the circumferential direction of the stator core, with the deflection directions being opposite and away from each other.

8. The stator assembly according to claim 1, wherein: Each phase of the stator winding includes 1 or an even number greater than or equal to 2 branches.

9. The stator assembly according to claim 8, characterized in that When each phase of the stator winding includes one branch, the input end and the output end of the branch are located at the innermost layer of the winding layer, and the other is located at the outermost layer; when each phase of the stator winding includes an even number of branches greater than or equal to 2, the input ends of half of the branches are located at the innermost layer of the winding layer, and the output ends are located at the outermost layer, and the input ends of the remaining branches are located at the outermost layer of the winding layer, and the output ends are located at the innermost layer.

10. A motor characterized by The stator assembly comprises any one of claims 1 to 9.

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