Stator winding, stator and axial flux motor

Abstract

The invention discloses a stator winding, a stator and an axial flux motor, the stator winding comprises a plurality of stacked printed circuit board structures, each printed circuit board structure is formed by laminating a first number of single-layer printed circuit boards, each printed circuit board comprises a substrate and a plurality of coils corresponding to a plurality of stator cores one by one, a through hole for embedding a corresponding stator core is formed in an area surrounded by each coil, the coils of all layers corresponding to the same stator core in the printed circuit board structure are coaxially arranged, the coils of adjacent layers are connected end to end to form coil groups, and the current directions of the coils of all layers in each coil group are the same; the plurality of conductive bonding pads are arranged on the outermost printed circuit board, and each conductive bonding pad corresponds to one coil group and is connected with the coil group; and the adjacent printed circuit board structures are conductively connected through the conductive bonding pads corresponding to the same coil group. The super high-rise PCB winding with higher torque / power density is realized, the super high-rise PCB winding is easy to process, and the cost is reduced.

Description

Technical Field

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

[0002] Axial flux motors, also known as disc motors, have gained increasing attention in the motor industry due to their compact axial dimensions, high electromechanical conversion efficiency, and high power and torque density. Among them, printed circuit board (PCB) windings manufactured based on PCB (Printed Circuit Board) technology are very suitable for use as stator windings in micro axial flux motors that have high requirements for installation space because of their small thickness and small length / diameter ratio.

[0003] However, the PCB winding in the related art is limited by the PCB board manufacturing process and materials, and the number of PCB layers in the PCB winding is limited. Generally, 16 layers is the limit and the cost is very expensive, which limits the improvement of the torque / power density of the PCB winding and cannot meet the requirements of higher torque / power density. Summary of the invention

[0004] In order to solve the problems of the prior art, the embodiments of the present application provide a stator winding, a stator and an axial flux motor. The technical solution is as follows:

[0005] In one aspect, a stator winding is provided, comprising:

[0006] A plurality of printed circuit board structures arranged in layers, each of which is formed by laminating a first number of single-layer printed circuit boards, each layer of the printed circuit board comprising a substrate and a plurality of coils formed on the substrate, the plurality of coils corresponding to a plurality of stator cores one by one, a through hole for embedding the corresponding stator core is formed in the area surrounded by each coil, each layer of coils corresponding to the same stator core in each of the printed circuit board structures is coaxially arranged and the coils of adjacent layers are connected end to end to form a coil group, and the current direction of each layer of coils in each coil group is the same;

[0007] A plurality of conductive pads are arranged on the outermost printed circuit board of each printed circuit board structure, each conductive pad corresponds to one coil group and is connected to the coil of the coil group on the outermost printed circuit board;

[0008] Wherein, the adjacent printed circuit board structures are conductively connected via the conductive pads corresponding to the same coil group on the outermost printed circuit boards of the respective structures.

[0009] In some exemplary embodiments, the printed circuit board structure is formed by stacking a second number of identical printed circuit board units, the printed circuit board unit includes a preset number of stacked printed circuit boards, and the head end and the tail end of each coil in the printed circuit board differ by a first angle in the plane coordinate system of the printed circuit board, and the first angle ranges from 60° to 120°;

[0010] The head ends and tail ends of the coils of adjacent layers corresponding to the same coil group in the printed circuit board unit are aligned and connected in the axial direction, and the product of the preset number and the first angle matches the circumferential angle.

[0011] In some exemplary embodiments, coils in adjacent layers in the same coil group in the printed circuit board structure are connected end to end via a plurality of parallel metallization interlayer vias disposed on the substrate.

[0012] In some exemplary embodiments, the plurality of parallel metallization interlayer vias include a first metallization interlayer via and a second metallization interlayer via, and a spacing between the first metallization interlayer via and the second metallization interlayer via is greater than 0.05 mm;

[0013] One coil in adjacent layers of the same coil group connects the first end of the via between the first metallization layers and the first end of the via between the second metallization layers, and another coil in adjacent layers of the same coil group connects the second end of the via between the first metallization layers and the second end of the via between the second metallization layers, so that the coils of the adjacent layers are connected end to end.

[0014] In some exemplary embodiments, the plurality of coil groups form a multi-phase winding, each phase winding includes a third number of spaced coil groups, the coil groups in each phase winding are interconnected, and two adjacent coil groups in the same phase winding include coil groups corresponding to other phase windings, respectively.

[0015] In some exemplary embodiments, the plurality of coil groups form a multi-phase winding, each phase winding includes a third number of adjacent coil groups, the coil groups in each phase winding are interconnected, and the current directions in two adjacent coil groups in the same phase winding are opposite.

[0016] In some exemplary embodiments, the conductive pads corresponding to the same coil group of each printed circuit board structure are aligned in the axial direction;

[0017] The conductive pad comprises a pad body and a blind hole located in the middle of the pad body, and the two conductive pads for the conductive connection are connected by conductive glue injected into the blind hole.

[0018] In some exemplary embodiments, the conductive pads corresponding to the same coil group of each printed circuit board structure are aligned in the axial direction; and the two conductive pads for conductive connection are conductively connected by soldering.

[0019] On the other hand, a stator is also provided, which includes the stator winding described in the embodiment of the present application and a stator core embedded in each through hole of the stator winding.

[0020] On the other hand, an axial flux motor is also provided, which includes the aforementioned stator of the embodiment of the present application.

[0021] The stator winding of the embodiment of the present application includes a plurality of stacked printed circuit board structures, each printed circuit board structure is formed by stacking a first number of single-layer printed circuit boards, each layer of the printed circuit board includes a substrate and a plurality of coils formed on the substrate, the plurality of coils correspond one-to-one to a plurality of stator cores, and the area surrounded by each coil is formed with a through hole for embedding the corresponding stator core, the coils of each layer corresponding to the same stator core in each printed circuit board structure are coaxially arranged and the coils of adjacent layers are connected end to end to form a coil group, and the current direction of each layer of the coils in each coil group is the same; the stator winding also includes an outermost printed circuit board arranged in each printed circuit board structure. Multiple conductive pads on the board, each conductive pad corresponds to a coil group, and is connected to the coil of the coil group on the outermost printed circuit board, wherein adjacent printed circuit board structures are conductively connected through the conductive pads corresponding to the same coil group on their respective outermost printed circuit boards, thereby realizing the stacking arrangement of multiple printed circuit board structures by connecting the conductive pads with exposed end faces, thereby breaking the limitations of PCB board manufacturing process and materials, and realizing ultra-high-layer (such as 48-layer PCB or higher 200-layer PCB) PCB windings with higher torque / power density, and easy to process, which is beneficial to reducing the cost of stator windings and improving the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a schematic diagram of the structural decomposition of a stator winding provided in an embodiment of the present application;

[0024] Figure 2 is a schematic structural diagram of a top printed circuit board of a printed circuit board structure provided in an embodiment of the present application;

[0025] Figure 3 It is an exploded schematic diagram of coils of each layer corresponding to the same coil group in the printed circuit board unit provided in an embodiment of the present application;

[0026] Figure 4 is a schematic diagram of parallel metallization interlayer vias provided in an embodiment of the present application;

[0027] Figure 5 It is a schematic diagram of a plurality of coil groups provided in an embodiment of the present application forming a multi-phase winding;

[0028] Figure 6 is another schematic diagram of a plurality of coil groups forming a multi-phase winding provided in an embodiment of the present application;

[0029] The following is a supplementary description of the attached drawings:

[0030] 100-stator winding; 110-printed circuit board structure; 120-conductive pad; 111-printed circuit board; 111a-substrate; 111b-coil; 111c-through hole; 401-via between the first metallization layer; 402-via between the second metallization layer; 301, 302, 303, 304, 305, 403, 404-coil; 301a, 302a, 303a, 304a-coil head end; 301b, 302b, 303b, 304b-coil tail end. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may include one or more of the features explicitly or implicitly. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here.

[0033] When a numerical range is disclosed herein, the above range is deemed to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges included therein. For example, a specified range from "1 to 10" should be deemed to include any and all sub-ranges between a minimum of 1 and a maximum of 10. Exemplary sub-ranges of ranges 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0034] The PCB winding in the related art is limited by the PCB board manufacturing process and materials. The number of PCB layers in the PCB winding is limited. Generally, 16 layers is the limit and the cost is very expensive. If more PCB layers are stacked, the PCB winding will be damaged due to excessive pressure on the PCB board, thereby limiting the improvement of the torque / power density of the PCB winding and failing to meet the requirements of higher torque / power density.

[0035] In view of this, the present application embodiment provides a stator winding, see Figure 1 , which shows a structural decomposition schematic diagram of a stator winding provided in an embodiment of the present application. It should be noted that the stator winding in the embodiment of the present application is formed based on a printed circuit board (PCB), so the stator winding can also be called a PCB winding.

[0036] Specifically, Figure 1 As shown, the stator winding 100 includes a plurality of stacked printed circuit board structures 110 , and the printed circuit board structure 110 is formed by stacking a first number of single-layer printed circuit boards 111 .

[0037] The first number can be determined based on the upper limit of the number of times the PCB board can withstand pressure in actual applications, so as to ensure that the stacking of the first number of single-layer printed circuit boards will not cause damage to the PCB board. Exemplarily, the first number can be 12, that is, a single printed circuit board structure 110 is formed by stacking 12 single-layer printed circuit boards PCB. In order to simplify the description, the single-layer printed circuit board is referred to as a printed circuit board below.

[0038] The printed circuit board 111 includes a substrate 111a and a plurality of coils 111b formed on the substrate 111a. Figure 2 The schematic diagram of the structure of the top printed circuit board of the printed circuit board structure is shown, and the multiple coils 111b correspond to multiple stator cores (not shown in the figure) one by one, and the area surrounded by each coil 111b is formed with a through hole 111c for embedding the corresponding stator core. Specifically, the multiple coils 111b can be evenly spaced and distributed along the circumference of the substrate 111a.

[0039] The coils 111b of each layer corresponding to the same stator core in the printed circuit board structure 110 are coaxially arranged and the coils of adjacent layers are connected end to end to form a coil group corresponding to the stator core, and the current direction of each layer of coils in each coil group is the same. It can be understood that there is a one-to-one correspondence between the coils, coil groups, and stator cores. Among them, the end-to-end connection between the coils of adjacent layers in each coil group refers to the connection between the head end (i.e., the current inlet end) of the coil of one layer in the adjacent layers and the tail end (i.e., the current outflow end) of the coil of another layer. Specifically, the end-to-end connection can be a head-to-tail series connection or a head-to-tail parallel connection.

[0040] Continue to see Figure 1 and Figure 2 The stator winding 110 further includes a plurality of conductive pads 120 disposed on the outermost printed circuit board of the printed circuit board structure 110 , each conductive pad 120 corresponds to a coil group and is connected to the coil of the corresponding coil group on the outermost printed circuit board.

[0041] Specifically, for the printed circuit board structure 110, the outermost printed circuit board includes a top printed circuit board and a bottom printed circuit board, and the plurality of conductive pads 120 are arranged on the top printed circuit board, and the plurality of conductive pads 120 are also arranged on the bottom printed circuit board. Since each conductive pad 120 needs to be connected to its corresponding coil group, each conductive pad 120 can be arranged on the outermost printed circuit board close to the coil group connected to it. Figure 2As shown, there are 9 coil groups, and 9 conductive pads 120 are arranged on the top printed circuit board, and each conductive pad 120 is connected to the coil of the corresponding coil group on the top printed circuit board.

[0042] In the embodiment of the present application, adjacent printed circuit board structures 110 are electrically connected through conductive pads 120 corresponding to the same coil group on the outermost printed circuit boards, thereby achieving reliable electrical and mechanical connection between the printed circuit board structures 110. The conductive pads 120 may be made of copper.

[0043] For example, assuming that the total design height of the stator winding 100 is 48 PCB layers (hereinafter referred to as 48 layers), and the printed circuit board structure 110 is formed by stacking 12 single-layer printed circuit boards 111, then 4 printed circuit board structures 110 can be selected to be stacked, and adjacent printed circuit board structures 110 are conductively connected through conductive pads corresponding to the same coil group on their outermost printed circuit boards.

[0044] In some specific embodiments, the conductive pads 120 corresponding to the same coil group of each printed circuit board structure 110 are aligned in the axial direction, and the conductive pads 120 include a pad body and a blind hole located in the middle of the pad body, and the two conductive pads for conductive connection are connected by the conductive glue injected into the blind hole. The blind hole in the middle of the conductive pad can provide a space for the conductive glue to overflow, and combined with the axial alignment setting, the flatness performance of the bonding can be improved, and the conductive ability and bonding force can also be enhanced.

[0045] In some specific implementations, the conductive pads 120 corresponding to the same coil group of each printed circuit board structure 110 are aligned in the axial direction, and the two conductive pads for conductive connection are conductively connected by soldering. Since the soldering method does not have specific requirements for the structure of the conductive pad, the production efficiency of the stator winding can be improved while saving the cost of the stator winding.

[0046] In the above technical solution of the present application, the printed circuit board structure 110 can be a prefabricated universal module. In practical applications, multiple printed circuit board structures 110 can be selected according to the total number of layers of the required stator winding, and then the multiple printed circuit board structures 110 are conductively connected in combination with the multiple conductive pads 120 on the outermost printed circuit board of the printed circuit board structure 110 to obtain the stator winding of the required number of layers, thereby realizing an ultra-high-layer (such as 48 layers, 200 layers or more) stator winding, and the stator winding has a higher torque / power density and is easy to process, which is beneficial to reducing the cost of the stator winding and improving the yield.

[0047] In some exemplary embodiments, the printed circuit board structure 110 is formed by stacking a second number of printed circuit board units, the printed circuit board unit includes a preset number of stacked printed circuit boards, the head end (current inlet end) of each coil in the printed circuit board and the tail end (current outflow end) of the coil differ by a first angle in the plane coordinate system of the printed circuit board, the first angle ranges from 60° to 120°, and the head ends and tail ends of the coils of adjacent layers corresponding to the same coil group in the printed circuit board unit are aligned and connected in the axial direction, wherein the product of the preset number and the first angle matches the circumferential angle, that is, the product of the preset number and the first angle should be equal to 360°. Exemplarily, the printed circuit board unit may include four layers of stacked printed circuit boards, and the head end of each coil in the printed circuit board and the tail end of the coil may differ by 90° in the plane coordinate system of the printed circuit board.

[0048] It can be understood that the second number is smaller than the first number, and the second number can be calculated based on the first number and the number of layers of the printed circuit board in the printed circuit board unit.

[0049] Still using the above example for explanation, assuming that the printed circuit board structure 110 includes 12 layers of printed circuit boards 111, the printed circuit board unit is composed of four stacked printed circuit boards, and the head end of each coil in the printed circuit board and the tail end of the coil can differ by 90° in the plane coordinate system of the printed circuit board, then the 12-layer printed circuit board 111 can be obtained by stacking three of the above printed circuit board units. Figure 3 The figure shows an exploded schematic diagram of coils of each layer corresponding to the same coil group in a printed circuit board unit, such as Figure 3 As shown, coils 301-304 are coils of each layer corresponding to the same coil group in the printed circuit board unit, wherein the current input end in each layer of the coil is the head end of the coil, and the current output end is the tail end of the coil. Taking coil 302 as an example, its head end 302a and its tail end 302b differ by 90° in the plane coordinate system of the printed circuit board.

[0050] Specifically, the tail end 301b of coil 301 is aligned with and connected to the head end 302a of coil 302 in the axial direction, the tail end 302b of coil 302 is aligned with and connected to the head end 303a of coil 303 in the axial direction, and the tail end 303b of coil 303 is aligned with and connected to the head end 304a of coil 304 in the axial direction. In this way, the wiring of different layers can not only make the current directions in coils 301-304 the same, but also make the tail end 304b of coil 304 and the head end 301a of coil 301 in the axial direction. If it is necessary to stack coils with the same current direction, such as Figure 3For the coil 305 in the circuit board, the wiring method of the coil 305 is the same as that of the coil 301, that is, the coils 301-304 can be regarded as a coil unit, so the four-layer printed circuit board corresponding to the coils 301-304 can be regarded as a printed circuit board unit, and the printed circuit board structure 110 including 12 layers of printed circuit boards can be realized by stacking multiple printed circuit board units, so that the ultra-high-layer stator winding has a higher torque / power density, and the more sophisticated modular wiring is conducive to further reducing the cost of the stator winding and improving the yield of the stator winding.

[0051] In some exemplary embodiments, coils in adjacent layers in the same coil group in the printed circuit board structure 110 are connected end to end through a plurality of parallel metallization interlayer vias disposed on the substrate 111a, for example, in series connection or in parallel connection.

[0052] Specifically, the multiple parallel metallization interlayer vias are spaced apart from each other. A multiple spaced through holes can be firstly drilled on the substrate 111a by laser, and then copper is coated on the through holes to form a multiple spaced metallization interlayer vias. One end of the multiple spaced metallization interlayer vias is respectively connected to a coil in the adjacent layer coil, and the other end of the multiple spaced metallization interlayer vias is respectively connected to another coil in the adjacent layer coil, so that the multiple spaced metallization interlayer vias connect the ends of the adjacent layer coils in parallel.

[0053] In a specific embodiment, Figure 4 As shown, the plurality of parallel metallization interlayer vias may include a first metallization interlayer via 401 and a second metallization interlayer via 402, and the spacing between the first metallization interlayer via 401 and the second metallization interlayer via 402 may be set to be greater than 0.05 mm; the end of a coil in an adjacent layer coil in the same coil group, such as Figure 4 The tail end of the coil 403 in the embodiment is connected to the first end of the first metallization layer via 401 and the second metallization layer via 402. Figure 4 The first end is the lower end of the metallization interlayer via 401, 402, and the end of another coil in the adjacent layer coil in the same coil group, such as Figure 4 The first end of the coil 404 in the embodiment is connected to the second end of the first metallization layer via 401 and the second metallization layer via 402, wherein the first end is arranged opposite to the second end. Figure 4 The second end is the upper end of the metallization interlayer vias 401 and 402, so that the coils 403 and 404 of the adjacent layers are connected in series end to end.

[0054] In practical applications, the shape of the vias between metallization layers can be circular or square, and this application does not make specific restrictions on this. The number of vias between metallization layers can also be set to more according to actual needs. Among them, due to process limitations, the aperture of a single hole formed by laser cannot be less than 0.1mm, and the aperture of a single hole formed by mechanical drilling cannot be less than 0.15mm.

[0055] The above implementation method connects coils of adjacent layers in the same coil group end to end by connecting multiple vias between metallization layers in parallel, thereby meeting the current carrying requirements while avoiding the problem of a single hole size not being too large due to process limitations, thereby improving the current carrying adaptation flexibility of the stator winding.

[0056] In some exemplary embodiments, multiple coil groups form a multi-phase winding, each phase winding includes a third number of spaced coil groups, the coil groups in each phase winding are interconnected, and two adjacent coil groups in the same phase winding include coil groups corresponding to other phase windings.

[0057] The third number is smaller than the total number of coil groups and can be calculated based on the total number of coil groups and the number of phases. The coil groups in each phase winding can be connected in series or in parallel.

[0058] Take 9 coil groups forming a 3-phase winding (hereinafter referred to as A-phase winding, B-phase winding, and C-phase winding) as an example. Figure 5 As shown, each phase winding includes three spaced coil groups. Taking the A-phase winding as an example, the A-phase winding includes coil group A1, coil group A2 and coil group A3. The coil group A1, coil group A2 and coil group A3 are connected in series with each other, and the coil group A1 includes a coil group B1 corresponding to the B-phase winding and a coil group C1 corresponding to the C-phase winding, the coil group A2 includes a coil group B2 corresponding to the B-phase winding and a coil group C2 corresponding to the C-phase winding, and the coil group A3 includes a coil group B3 corresponding to the B-phase winding and a coil group C3 corresponding to the C-phase winding between the coil group A1 and the coil group A3.

[0059] In the above embodiment, each phase winding includes a third number of coil groups arranged at intervals and connected to each other, and two adjacent coil groups in the same phase winding include coil groups corresponding to other phase windings, so that the current directions between adjacent coil groups in the same layer can be the same. Figure 5 As shown, the current direction in all coil groups can be clockwise, so that force balance can be achieved, which is beneficial to improving the control stability of the motor based on the stator winding.

[0060] In some exemplary embodiments, a plurality of coil groups form a multi-phase winding, each phase winding includes a third number of adjacent coil groups, the coil groups in each phase winding are interconnected, and the current directions in two adjacent coil groups in the same phase winding are opposite. The coil groups in each phase winding may be connected in series or in parallel.

[0061] Still taking 9 coil groups forming a 3-phase winding as an example, Figure 6 As shown, each phase winding includes three adjacent coil groups, such as coil groups a1, a2, and a3, which are adjacent and connected in series to form a phase winding. In this phase winding, the current directions in coil group a1 and coil group a2 are opposite, and the current directions in coil group a2 and coil group a3 are opposite, and the other phase windings are similar.

[0062] In the above-mentioned embodiment, each phase winding includes a third number of coil groups that are adjacently arranged and interconnected, and the current directions in two adjacent coil groups in the same phase winding are opposite, thereby achieving the same coil winding direction between the coil groups in the same phase winding, which is beneficial to simplify the wiring of the stator winding and improve the production efficiency of the stator winding.

[0063] An embodiment of the present application further provides a stator, comprising any one of the aforementioned stator windings of the embodiments of the present application and a stator core embedded in each through hole of the stator winding.

[0064] The embodiment of the present application also provides an axial flux motor, which includes the aforementioned stator of the embodiment of the present application.

[0065] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A stator winding, characterized in that: include: A plurality of printed circuit board structures (110) arranged in layers, the printed circuit board structure (110) being formed by laminating a first number of single-layer printed circuit boards (111), the printed circuit board (111) comprising a substrate (111a) and a plurality of coils (111b) formed on the substrate (111a), the plurality of coils (111b) corresponding one to one to a plurality of stator cores, a through hole (111c) for embedding a corresponding stator core is formed in an area surrounded by each coil (111b), the coils (111b) of each layer corresponding to the same stator core in the printed circuit board structure (110) are coaxially arranged and the coils (111b) of adjacent layers are connected end to end to form a coil group, and the current directions of the coils (111b) of each layer in each coil group are the same; A plurality of conductive pads (120) are arranged on the outermost printed circuit board of the printed circuit board structure (110), each conductive pad (120) corresponds to one of the coil groups and is connected to the coil (111b) of the coil group on the outermost printed circuit board; Wherein, adjacent printed circuit board structures (110) are electrically connected via the conductive pads (120) corresponding to the same coil group on their respective outermost printed circuit boards.

2. The stator winding according to claim 1, characterized in that: The printed circuit board structure (110) is formed by stacking a second number of printed circuit board units, the printed circuit board unit comprising a preset number of stacked printed circuit boards (111), the head end and the tail end of each coil (111b) in the printed circuit board (111) differing by a first angle in a plane coordinate system of the printed circuit board (111), the first angle being in a range of 60° to 120°; The head ends and tail ends of adjacent layer coils (111b) corresponding to the same coil group in the printed circuit board unit are aligned in the axial direction and connected, and the product of the preset number and the first angle matches the circumferential angle.

3. The stator winding according to claim 2, characterized in that: The coils of adjacent layers in the same coil group in the printed circuit board structure (110) are connected end to end via a plurality of parallel metallized interlayer vias arranged on the substrate (111a).

4. The stator winding according to claim 3, characterized in that: The plurality of parallel metallization interlayer vias include a first metallization interlayer via (401) and a second metallization interlayer via (402), and a spacing between the first metallization interlayer via (401) and the second metallization interlayer via (402) is greater than 0.05 mm; One coil in adjacent layers of the same coil group is connected to a first end of the first metallization layer via (401) and a first end of the second metallization layer via (402), and another coil in adjacent layers of the same coil group is connected to a second end of the first metallization layer via (401) and a second end of the second metallization layer via (402), so that the coils of the adjacent layers are connected end to end, wherein the first end is arranged opposite to the second end.

5. The stator winding according to claim 1, characterized in that: The plurality of coil groups form a multi-phase winding, each phase winding includes a third number of spaced coil groups, the coil groups in each phase winding are interconnected, and two adjacent coil groups in the same phase winding include coil groups corresponding to other phase windings.

6. The stator winding according to claim 1, characterized in that: The plurality of coil groups form a multi-phase winding, each phase winding includes a third number of adjacent coil groups, the coil groups in each phase winding are connected to each other, and the current directions of two adjacent coil groups in the same phase winding are opposite.

7. The stator winding according to any one of claims 1 to 6, characterized in that: The conductive pads (120) corresponding to the same coil group of each printed circuit board structure (110) are arranged in alignment in the axial direction; The conductive pad (120) comprises a pad body and a blind hole located in the middle of the pad body, and the two conductive pads (120) for the conductive connection are connected by means of conductive glue injected into the blind hole.

8. The stator winding according to any one of claims 1 to 6, characterized in that: The conductive pads (120) corresponding to the same coil group of each printed circuit board structure (110) are arranged in alignment in the axial direction; and the two conductive pads (120) for the conductive connection are conductively connected by soldering.

9. A stator, characterized in that: The invention comprises a stator winding according to any one of claims 1 to 8 and a stator core embedded in each through hole of the stator winding.

10. An axial flux motor, characterized in that: Comprising the stator as claimed in claim 9.

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