A coreless PCB stator winding for an axial flux motor, a stator assembly and an axial flux motor

Abstract

The application belongs to the technical field of axial flux motors, and particularly relates to a coreless PCB stator winding for an axial flux motor, a stator assembly and an axial flux motor, wherein the coreless PCB stator winding comprises at least one winding unit, the winding unit comprises a first annular substrate and a second annular substrate, and the front surface and the back surface of the two annular substrates jointly form four conductor layers, each conductor layer has conductor wires constituting a planar coil in a corresponding sector; the planar coil comprises a conductor action edge and a conductor connection edge, and the planar coils in different conductor layers are staggered and arranged in a mirror image, staggered and filled with a complementary position; the conductor action edge in the third conductor layer is located in a gap region between the front two planar coils; the application can improve the conductor utilization rate in the effective magnetic flux cutting region, and improve the interlayer conduction and current distribution performance of the multi-layer winding.

Description

Technical Field

[0001] This invention belongs to the field of axial flux motor technology, specifically relating to a coreless PCB stator winding, stator assembly, and axial flux motor for an axial flux motor. Background Technology

[0002] Axial flux motors offer advantages such as compact structure, high torque density, and ease of flattening design, making them suitable for applications requiring high power density, miniaturization, and lightweighting. To meet these needs, existing technologies utilize PCBs to form coreless stator windings, replacing traditional wound stators and improving manufacturing consistency while facilitating multi-layer stacking.

[0003] However, existing coreless PCB stator windings still have the following problems: First, existing planar coils are usually only routed as a whole from the perspective of forming a closed loop, without effectively distinguishing between the conductor side that actually participates in magnetic flux cutting and the conductor connection side that only serves to connect. This results in a low proportion of conductor side in a limited space, while the conductor connection side occupies a large amount of routing area, affecting the conductor utilization rate in the effective area of ​​magnetic flux cutting. Second, most existing multilayer PCB windings adopt simple repeated stacking or conventional mirroring methods, and there is a lack of staggered filling design for gap areas between conductors in the layers. Even if the number of layers is increased, it is difficult to significantly increase the number of effective conductor sides in the unit pole pair space. Third, for three-phase windings, existing coreless PCB stators usually lack an equivalent slot organization method for the mechanical space corresponding to a pair of magnetic poles, and fail to cross-interlace and arrange the conductor side of each phase in a regular phase sequence according to a high density. In addition, existing multilayer PCB windings usually rely on a small number of through holes or simple interlayer conduction structures for interlayer connections, which easily leads to problems such as large interlayer connection impedance, uneven current distribution, and local hot spot concentration.

[0004] Therefore, it is necessary to provide a coreless PCB stator winding structure for axial flux motors to improve the arrangement density of conductor action edges in the effective area of ​​flux cutting, optimize the mirror, misalignment and compensation relationships between multilayer planar coils, and improve the interlayer current bus and commutation connection methods, thereby improving the conductor utilization rate, current distribution uniformity and overall performance of the winding. Summary of the Invention

[0005] In view of this, the present invention provides a coreless PCB stator winding, stator assembly, and axial flux motor for an axial flux motor, so as to improve the conductor utilization rate in the effective area of ​​flux cutting, enhance the interlayer conductivity of multilayer planar coils, and balance the current distribution. It solves the problems of low conductor active side ratio, insufficient utilization of interlayer gaps, insufficient compact organization of three-phase conductor active sides in pole pair space, large interlayer connection impedance, and easy concentration of local hot spots in the existing coreless PCB stator windings of axial flux motors.

[0006] To solve the above-mentioned technical problems, in a first aspect, the present invention provides a coreless PCB stator winding for an axial flux motor, wherein the coreless PCB stator winding includes at least one winding unit, the winding unit including a first annular substrate and a second annular substrate stacked along the axial direction, the front and back sides of the first annular substrate are respectively provided with a first conductor layer and a second conductor layer, the front and back sides of the second annular substrate are respectively provided with a third conductor layer and a fourth conductor layer, and the third conductor layer and the second conductor layer are bonded together by an insulating adhesive material;

[0007] The first and second annular substrates are respectively divided into multiple sectors along their respective circumferences. Each conductor layer contains conductor lines that form a planar coil within its corresponding sector, and each conductor layer includes a complete planar coil within its corresponding sector.

[0008] The planar coil includes a conductor action edge and a conductor connection edge. The conductor action edge is located in a radial straight conductor segment within the effective magnetic flux cutting region. The conductor connection edge is located in the inner and outer peripheral edge regions of the first and second annular substrates, and is used to connect adjacent conductor action edges. Planar coils located in different conductor layers and formed in corresponding sectors are arranged alternately. The planar coils in the first conductor layer are mirror images of the planar coils in the second conductor layer to form conductor action edges on both sides of the corresponding sector. The planar coils in the third conductor layer are offset relative to the first and second conductor layers, and their conductor action edges are located in the gap region between the planar coils in the first and second conductor layers to fill the gap between the first and second conductor layers. The planar coils in the fourth conductor layer are mirror images of the planar coils in the third conductor layer.

[0009] On the first annular substrate and the second annular substrate, the conductors forming planar coils in the plurality of sectors form U-phase windings, V-phase windings and W-phase windings in a predetermined phase sequence. Each planar coil forming the U-phase winding, V-phase winding and W-phase winding has at least two conductor action sides. The mechanical space corresponding to a pair of magnetic poles is divided into six virtual slots at equal intervals. The conductor action sides of each phase occupy two virtual slots in a predetermined phase sequence.

[0010] The wide copper busbar region formed by the planar coil ends between adjacent conductor layers and the switching and commutation region between conductor layers are interconnected and connected in parallel through a via array.

[0011] Preferably, the sectors on the first annular substrate and the second annular substrate are arranged corresponding to each other in the axial direction.

[0012] Preferably, the planar coil is a rectangular multi-turn planar coil, and the rectangular multi-turn planar coil is formed by sequentially connecting the two conductor working edges and the two conductor connecting edges end to end to form a closed loop.

[0013] Preferably, the starting point of the wire of the planar coil in the first conductor layer is located on one side of the inner rectangular area of the rectangle and is routed along the first direction;

[0014] The starting point of the wire of the planar coil in the second conductor layer is the same as that of the planar coil in the first conductor layer, and is routed along the second direction opposite to the first direction, so as to form a mirror arrangement of the planar coil in the first conductor layer and the planar coil in the second conductor layer.

[0015] Preferably, the planar coil in the third conductor layer is arranged in a dislocation relative to the first conductor layer and the second conductor layer, and the dislocation amount is one-half of the center distance between adjacent conductor working edges in the first conductor layer and the second conductor layer, so that the conductor working edge in the third conductor layer is inserted between adjacent conductor working edges in the first conductor layer and the second conductor layer; the starting point of the wire of the planar coil in the third conductor layer is located on one side of the inner rectangular area of the rectangle and is also routed along the first direction;

[0016] The starting point of the wire of the planar coil in the fourth conductor layer is the same as that of the planar coil in the third conductor layer, and is also routed along the second direction opposite to the first direction, so as to form a mirror arrangement of the planar coil in the third conductor layer and the planar coil in the fourth conductor layer.

[0017] Preferably, the through-hole array includes a blind-hole array and a via-hole array. Among them, the blind-hole array is located in the wide copper busbar area, and the blind-hole array is a plurality of blind holes distributed in a two-dimensional array. The planar coil in the first conductor layer and the planar coil in the second conductor layer are connected through the blind-hole array provided on the first annular substrate; the planar coil in the third conductor layer and the planar coil in the fourth conductor layer are connected through the blind-hole array provided on the second annular substrate;

[0018] The via-hole array is located in the transfer commutation area, and the via-hole array is a plurality of vias distributed in an arc array. The planar coil in the second conductor layer and the planar coil in the third conductor layer are connected through the via-hole array, so that the wire is transferred from the second conductor layer to the third conductor layer.

[0019] Preferably, among the six virtual slot positions corresponding to a pair of magnetic poles, the conductor working edges of the planar coils in the U-phase winding, V-phase winding, and W-phase winding are arranged in a circumferential cross pattern according to the predetermined phase sequence of U, V, and W and alternately occupy the six virtual slot positions.

[0020] In a second aspect, the present invention provides a stator assembly for an axial flux motor, the stator assembly comprising a thermally conductive insulating layer, a metal heat dissipation frame, and a coreless PCB stator winding for an axial flux motor as described above.

[0021] The coreless PCB stator winding is attached to the metal heat sink frame through the thermally conductive insulating layer.

[0022] Thirdly, the present invention provides an axial flux motor, including a rotor assembly and a stator assembly, wherein the stator assembly is the stator assembly for an axial flux motor described above.

[0023] The rotor assembly includes a rotor disk and a permanent magnet disposed on the rotor disk, and the conductor action side of the coreless PCB stator winding is located within the effective magnetic flux cutting area corresponding to the permanent magnet.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. Improve conductor utilization within the effective area of ​​flux cutting: This invention sets closed planar coils in multiple sectors of a ring substrate and divides the conductors in the planar coils into conductor action edges and conductor connection edges. The radial straight conductor segments located within the effective area of ​​flux cutting are used as the main conductor action edges, while the conductor connection edges used to connect adjacent conductor action edges are arranged in the inner and outer peripheral edge areas. This reduces the occupation of effective wiring space by non-main conductors and increases the number of effective conductor edges per unit area.

[0026] 2. Improve the space filling rate and active edge density of multilayer planar coils: In this invention, the planar coils in the first conductor layer and the second conductor layer are arranged in a mirror image. The planar coils in the third conductor layer are staggered relative to the first two layers and located in the gap area between the planar coils of the first two layers. The planar coils in the fourth conductor layer and the third conductor layer are arranged in a mirror image. This allows the planar coils in different conductor layers to form an interlaced and complementary arrangement in the corresponding sectors, enabling more active conductor edges to be arranged in a limited sector space, thereby improving the space utilization of multilayer coils.

[0027] 3. Achieving an orderly organization of the three-phase conductor action sides within the space corresponding to a pair of magnetic poles: This invention divides the mechanical space corresponding to a pair of magnetic poles into six virtual slots at equal intervals, and makes the conductor action sides of the U-phase winding, V-phase winding and W-phase winding occupy the virtual slots respectively according to a predetermined phase sequence, thereby forming an equivalent slotted three-phase distribution in the coreless PCB stator structure, so that the conductor action sides of each phase can be cross-arranged, alternately occupied and organized in the space corresponding to the same magnetic pole pair, which is beneficial to improving the conductor arrangement efficiency within the pole pair space.

[0028] 4. Applicable to axial flux motors and helps improve overall performance: The coreless PCB stator winding of the present invention is suitable for axial flux motors. While maintaining the advantages of thinness, light weight and ease of PCB processing and manufacturing, it can increase the conductor edge density in the effective area of ​​flux cutting, improve interlayer connection and heat dissipation conditions, thereby helping to improve the output capacity, power density and operating stability of the motor. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a three-dimensional structural diagram of the winding unit of the coreless PCB stator winding in this invention;

[0031] Figure 2 This is a schematic diagram of the sector division of the first annular substrate in this invention;

[0032] Figure 3 This is a schematic diagram of the specific structure of the planar coil in this invention;

[0033] Figure 4 This is a schematic diagram of the wiring structure of the planar coil of the first conductor layer and the second conductor layer in this invention;

[0034] Figure 5 This is a schematic diagram of the wiring structure of the planar coils of the second conductor layer and the third conductor layer in this invention;

[0035] Figure 6 This is a schematic diagram of the wiring structure of the planar coils of the third conductor layer and the fourth conductor layer in this invention;

[0036] Figure 7 This is a schematic diagram showing the specific arrangement of the through-hole array on the first annular substrate in this invention;

[0037] Figure 8 This is a three-dimensional structural diagram of the conductor action side of each phase winding occupying a virtual slot in the three-phase winding of the present invention;

[0038] Figure 9 This is a front view schematic diagram of the conductor action side of each phase winding occupying a virtual slot in the three-phase winding of the present invention.

[0039] In the figure: First annular substrate 1, first conductor layer 1-1, second conductor layer 1-2; second annular substrate 2, third conductor layer 2-1, fourth conductor layer 2-2; sector 3; planar coil 4, conductor action edge 4-1, conductor connection edge 4-2; blind via 5; via 6; virtual slot 7. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] In this application, axial flux motor refers to a motor in which the direction of the magnetic field is parallel to the motor shaft, and the stator and rotor are arranged axially in a disc shape; coreless PCB stator winding refers to a stator winding structure that uses a printed circuit board, i.e., PCB technology to form stator winding conductors on a substrate, without setting an iron core. The winding is formed directly on the PCB copper foil through an etching process, completely eliminating the iron core structure, avoiding hysteresis loss and eddy current loss caused by the iron core structure, and improving motor efficiency.

[0043] In common coreless PCB stator windings, the three-phase windings usually lack an equivalent slot organization method for the mechanical space corresponding to a pair of magnetic poles. If the conductor action sides in each phase can be interlaced according to a certain rule phase sequence, then a high-density arrangement of the conductor action sides can be achieved, thereby improving the conductor utilization rate in the effective area of ​​magnetic flux cutting.

[0044] Therefore, this invention takes a winding unit as an example. Two annular substrates are arranged in an axial stack in the winding unit. Based on dividing the spatial positions on the two annular substrates into corresponding sectors, planar coils or coil portions within each sector are connected to form a conductor layer. Conductor layers are arranged on two planes of each annular substrate, resulting in a total of four conductor layers. The planar coils in the first and second conductor layers are arranged in a mirror image. The planar coils in the third conductor layer are offset relative to the first two layers and located in the gap region between the planar coils of the first two layers. The fourth conductor layer is arranged in a mirror image with the planar coils in the third conductor layer, thereby enabling the planar coils in different conductor layers to... By forming an interlaced and complementary arrangement within the corresponding sector, more conductor action sides can be arranged within a limited sector space, improving the space utilization of multilayer coils. Correspondingly, for three-phase windings, this invention divides the mechanical space corresponding to a pair of magnetic poles into six virtual slots at equal intervals, and makes the conductor action sides of the U-phase winding, V-phase winding, and W-phase winding occupy the virtual slots respectively according to a predetermined phase sequence. This forms an equivalent slotted three-phase distribution in the coreless PCB stator structure, enabling the conductor action sides of each phase to achieve cross arrangement, alternating occupation, and high-density organization within the corresponding space of the same magnetic pole pair. This is beneficial to improving the conductor arrangement efficiency within the pole pair space and greatly improving the magnetic flux utilization rate.

[0045] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0046] The first aspect of this invention provides a coreless PCB stator winding for an axial flux motor, such as... Figures 1-6 As shown, this application takes the coreless PCB stator winding used in an eight-pole axial flux motor as an example for illustration. Specifically, the coreless PCB stator winding includes at least one winding unit, which includes a first annular substrate 1 and a second annular substrate 2 stacked along the axial direction. The front and back sides of the first annular substrate 1 are respectively provided with a first conductor layer 1-1 and a second conductor layer 1-2. The front and back sides of the second annular substrate 2 are respectively provided with a third conductor layer 2-1 and a fourth conductor layer 2-2, and the third conductor layer 2-1 and the second conductor layer 1-2 are bonded together by an insulating adhesive material.

[0047] In this embodiment, the first annular substrate 1 and the second annular substrate 2 are respectively divided into multiple sectors 3 along their respective circumferences, and the sectors 3 on the first annular substrate 1 and the second annular substrate 2 are arranged correspondingly to each other in the axial direction. Each conductor layer contains conductor lines forming a planar coil 4 within its corresponding sector 3, and each conductor layer includes a complete planar coil 4 within its corresponding sector 3. Specifically, in this embodiment, as shown... Figure 2As shown, it is described by taking each sector 3 including a complete planar coil 4 as an example; in addition, the planar coil 4 includes a conductor active side 4-1 and a conductor connecting side 4-2. The conductor active side 4-1 is a radial straight conductor segment located within the effective flux cutting region, and the conductor connecting side 4-2 is located in the inner peripheral region and the outer peripheral region of the first annular substrate 1 and the second annular substrate 2, and is used to connect adjacent conductor active sides 4-1.

[0048] Here, it should be noted that the effective flux cutting region refers to the annular space covered by the axial projection of the rotor permanent magnet in a conventional axial flux motor, that is, the air gap range where the magnetic lines of force perpendicularly pass through the PCB stator winding; this region defines the effective action boundary for the axial flux motor to generate electromagnetic torque. In this application, emphasizing that the "conductor active side 4-1" is located within this region aims to ensure that the radial wire segment can efficiently cut the magnetic lines of force to generate an induced electromotive force, thereby avoiding material waste and loss caused by the end copper wire being in a low magnetic field region.

[0049] As the core of this application, as Figures 3-6 shown, the planar coils located in different conductor layers are staggered. Among them, the planar coils in the first conductor layer 1-1 and the planar coils in the second conductor layer 1-2 are arranged in a mirror image to form conductor active sides 4-1 on both sides within the corresponding sector 3; the planar coils in the third conductor layer 2-1 are arranged offset relative to the first conductor layer 1-1 and the second conductor layer 1-2, and their conductor active sides 4-1 are located in the gap region between the planar coils of the first conductor layer 1-1 and the second conductor layer 1-2 to fill the gap between the first conductor layer 1-1 and the second conductor layer 1-2; the planar coils in the fourth conductor layer 2-2 are arranged in a mirror image with the planar coils in the third conductor layer 2-1.

[0050] More specifically, as Figure 3 shown, the planar coil 4 is a square-shaped multi-turn planar coil. This square-shaped multi-turn planar coil is formed by sequentially connecting the two conductor active sides 4-1 and the two conductor connecting sides 4-2 end to end to form a closed loop. Among them, the conductor active side 4-1 and the conductor connecting side 4-2 do not refer to two physically energized wires, but are multi-turn wires formed by combining several energized wires. In this application, this multi-turn wire is called the conductor active side 4-1 and the conductor connecting side 4-2.

[0051] The starting point of the wire of the planar coil 4 in the first conductor layer 1-1 is located on one side of the inner square-shaped region of the square and is wired in the first direction.

[0052] The starting point of the wire of the planar coil 4 in the second conductor layer 1-2 is the same as that of the planar coil 4 in the first conductor layer 1-1 and is wired in the second direction opposite to the first direction to form a mirror image arrangement of the planar coil 4 in the first conductor layer 1-1 and the planar coil 4 in the second conductor layer 1-2, forming as Figure 4The structure shown

[0053] The planar coil 4 in the third conductor layer 2-1 is arranged out of alignment with the first conductor layer 1-1 and the second conductor layer 1-2, and the misalignment amount is one-half of the center distance between adjacent conductor active edges 4-1 in the first conductor layer 1-1 and the second conductor layer 1-2, so that the conductor active edge 4-1 in the third conductor layer 2-1 is inserted between adjacent conductor active edges 4-1 in the first conductor layer 1-1 and the second conductor layer 1-2; the starting point of the wire of the planar coil 4 in the third conductor layer 2-1 is located on one side of the inner square area of the double-square and is also wired along the first direction, forming as Figure 5 The structure shown

[0054] The starting point of the wire of the planar coil 4 in the fourth conductor layer 2-2 is the same as that of the planar coil 4 in the third conductor layer 2-1, and is also wired along the second direction opposite to the first direction, so as to form a mirror arrangement of the planar coil 4 in the third conductor layer 2-1 and the planar coil 4 in the fourth conductor layer 2-2, forming as Figure 6 The structure shown

[0055] Based on the above structure, the planar coils 4 in different conductor layers form an interleaved and complementary arrangement relationship in the corresponding sector 3, which can arrange more conductor active edges in the limited space of the sector 3 and improve the space utilization rate of the multi-layer coil.

[0056] In addition, the "same wire starting point" described in the above structure description does not mean the same starting point in the strict three-dimensional space position, but the same in the axial projection direction, and the "starting point" does not strictly refer to the line routing in the stator winding application of the actual motor, but is used to characterize that there is a mirror wiring relationship between the planar coils of the conductor layers arranged on the front and back of the first annular substrate 1 or the second annular substrate 2, that is, there is a clockwise and counterclockwise mirror relationship; on this basis, the wide copper busbar area formed by leading out from the end of the planar coil 4 between adjacent conductor layers and the transfer commutation area between the conductor layers are interconnected and shunted in parallel through the via array.

[0057] Specifically, as Figure 7 shown, the via array includes a blind via array and a through via array. Among them, the blind via array is located in the wide copper busbar area, and the blind via array is multiple blind vias 5 distributed in a two-dimensional array. The planar coil 4 in the first conductor layer 1-1 is connected to the planar coil 4 in the second conductor layer 1-2 through the blind via array arranged on the first annular substrate 1; the planar coil 4 in the third conductor layer 2-1 is connected to the planar coil 4 in the fourth conductor layer 2-2 through the blind via array arranged on the second annular substrate 2.

[0058] The via array is located in the transition and reversal area, and the via array consists of multiple vias 6 arranged in an arc shape. The planar coil 4 in the second conductor layer 1-2 and the planar coil 4 in the third conductor layer 2-1 are connected through the via array so that the wire can be transferred from the second conductor layer 1-2 to the third conductor layer 2-1.

[0059] Based on this, the above-mentioned structural arrangement is the core arrangement between the four conductor layers in a winding unit, thereby increasing the proportion of the conductor active side 4-1 in the winding unit and solving the problem of insufficient utilization of the gaps between conductor layers. In practical applications, if the coreless PCB stator winding has only one winding unit, the remaining wire connection and component installation methods for the coreless PCB stator winding to function are all common methods in the prior art, based on the wiring concept of this technical solution for each conductor layer. Under the premise of ensuring that the coreless PCB stator winding can be used in practice, no limitation is made on these methods. In addition, if the coreless PCB stator winding includes multiple winding units, after the planar coil 4 in the fourth conductor layer 2-2 is arranged, the wires can be introduced into the next winding unit through insulating adhesive materials, and the wiring can continue in the above manner.

[0060] As another core aspect of this application, this technical solution, based on the specific wiring methods in the above four conductor layers, clarifies the arrangement of the conductor active side 4-1 of the three-phase winding in the pole pair space from the perspective of the three-phase winding, in order to solve the problems of insufficient compactness of the conductor active side 4-1 of the three-phase winding in the pole pair space, large interlayer connection impedance, and easy concentration of local hot spots.

[0061] like Figures 8-9 As shown, on the first annular substrate 1 and the second annular substrate 2, the conductors forming the planar coils 4 in multiple sectors 3 are arranged in a predetermined phase sequence to form U-phase windings, V-phase windings and W-phase windings. Each planar coil 4 that forms the U-phase winding, V-phase winding and W-phase winding has at least two conductor action sides 4-1. The mechanical space corresponding to a pair of magnetic poles is divided into six virtual slots 7 at equal intervals. The conductor action sides 4-1 of each phase occupy two virtual slots 7 respectively in a predetermined phase sequence.

[0062] Specifically, in the six virtual slots 7 corresponding to a pair of magnetic poles, the conductor action side 4-1 of the planar coil 4 in the U-phase winding, V-phase winding and W-phase winding is arranged circumferentially in a predetermined phase sequence of U, V and W and alternately occupies the six virtual slots 7. It should be noted that this embodiment is arranged in a predetermined phase sequence of U, V and W. In fact, those skilled in the art can arrange any phase sequence based on existing motor theory. Therefore, the phase sequence arrangement method of this embodiment is not shown in the figure.

[0063] In this embodiment, practically speaking, in a conventional three-phase axial flux motor, the mechanical space corresponding to a pair of magnetic poles must be filled with three-phase windings. That is, in the conventional three-phase winding arrangement, the three-phase windings are arranged in a space along the axial direction in an aligned and superimposed manner. This method has the problems of insufficient compactness of the conductor action side 4-1 of the three-phase winding in the pole pair space, large interlayer connection impedance, and easy concentration of local hot spots. If the wiring is done in the aforementioned manner of "mirroring, misalignment, and filling gaps", the following can be obtained: Figures 8-9 The three-phase winding wiring method shown is that in the six virtual slots 7 corresponding to a pair of magnetic poles, the three planar coils 4 of the three-phase windings, a total of six conductor action sides 4-1, are arranged circumferentially in a predetermined phase sequence of U, V, W and alternately occupy the six virtual slots 7.

[0064] A second aspect of the present invention provides a stator assembly for an axial flux motor, the stator assembly including a thermally conductive insulating layer, a metal heat sink frame, and a coreless PCB stator winding for an axial flux motor as described above.

[0065] The coreless PCB stator winding is attached to the metal heat sink frame through a thermally conductive insulating layer.

[0066] A third aspect of the present invention provides an axial flux motor, the axial flux motor including a rotor assembly and a stator assembly, the stator assembly being the stator assembly for an axial flux motor described above, and the stator assembly including a coreless PCB stator winding for an axial flux motor as described above.

[0067] The rotor assembly includes a rotor disk and a permanent magnet disposed on the rotor disk. The conductor action side 4-1 of the coreless PCB stator winding is located within the effective area of ​​magnetic flux cutting corresponding to the permanent magnet.

[0068] In this embodiment, the axial flux motor with the aforementioned coreless PCB stator winding can improve the conductor edge density within the effective area of ​​flux cutting while maintaining the advantages of thinness, light weight and ease of PCB processing and manufacturing. This improves interlayer connection and heat dissipation conditions, thereby helping to enhance the motor's output capacity, power density and operating stability.

[0069] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coreless PCB stator winding for an axial flux motor, characterized in that: The ironless PCB stator winding comprises at least one winding unit. The winding unit includes a first annular substrate and a second annular substrate which are stacked axially. A first conductor layer and a second conductor layer are provided on the front and back surfaces of the first annular substrate respectively. A third conductor layer and a fourth conductor layer are provided on the front and back surfaces of the second annular substrate respectively. And the third conductor layer is bonded to the second conductor layer through an insulating bonding material. The first annular substrate and the second annular substrate are respectively divided into a plurality of sectors along their respective circumferences. The conductor lines forming a planar coil exist in the corresponding sectors of each conductor layer. And each conductor layer includes a complete planar coil in the corresponding sector. The planar coil includes a conductor active side and a conductor connecting side. The conductor active side is a radial straight conductor segment located in the effective flux cutting area. The conductor connecting side is located in the inner peripheral area and the outer peripheral area of the first annular substrate and the second annular substrate and is used to connect adjacent conductor active sides. The planar coils formed in the corresponding sectors and located in different conductor layers are arranged staggeredly. Among them, the planar coils in the first conductor layer and the planar coils in the second conductor layer are arranged in a mirror image manner to form conductor active sides on both sides in the corresponding sector. The planar coils in the third conductor layer are arranged in a dislocation manner relative to the first conductor layer and the second conductor layer. And their conductor active sides are located in the gap area between the planar coils of the first conductor layer and the second conductor layer to fill the gap between the first conductor layer and the second conductor layer. The planar coils in the fourth conductor layer and the planar coils in the third conductor layer are arranged in a mirror image manner. On the first annular substrate and the second annular substrate, the conductor lines forming planar coils in a plurality of the sectors form a U-phase winding, a V-phase winding and a W-phase winding according to a predetermined phase sequence. Each planar coil constituting the U-phase winding, the V-phase winding and the W-phase winding has at least two conductor active sides. The mechanical space corresponding to a pair of magnetic poles is equally divided into six virtual slot positions at equal intervals. The conductor active sides of each phase respectively occupy two virtual slot positions according to a predetermined phase sequence. The wide copper busbar area formed by leading out from the end of the planar coil between adjacent conductor layers and the transfer commutation area between the conductor layers are interconnected in layers and shunted in parallel through a via hole array.

2. The coreless PCB stator winding for an axial flux motor according to claim 1, characterized in that: The sectors on the first annular substrate and the second annular substrate are arranged corresponding to each other in the axial direction.

3. A coreless PCB stator winding for an axial flux motor according to claim 2, characterized in that: The planar coil is a square multi-turn planar coil. The square multi-turn planar coil is formed by sequentially connecting the two conductor active sides and the two conductor connecting sides end to end to form a closed loop.

4. A coreless PCB stator winding for an axial flux motor according to claim 3, characterized in that: The starting point of the wire of the planar coil in the first conductor layer is located on one side of the inner square area of the square and is wired along the first direction. The starting point of the wire of the planar coil in the second conductor layer is the same as that of the planar coil in the first conductor layer and is wired along the second direction opposite to the first direction to form a mirror image arrangement of the planar coil in the first conductor layer and the planar coil in the second conductor layer.

5. A coreless PCB stator winding for an axial flux motor according to claim 4, characterized in that: The planar coil in the third conductor layer is arranged offset relative to the first conductor layer and the second conductor layer, and the offset amount is one-half of the center distance between adjacent conductor active edges in the first conductor layer and the second conductor layer, so that the conductor active edges in the third conductor layer are inserted between adjacent conductor active edges in the first conductor layer and the second conductor layer; the starting point of the wire of the planar coil in the third conductor layer is located on one side of the inner square-shaped area of the square within a square and is also wired along the first direction; The starting point of the wire of the planar coil in the fourth conductor layer is the same as that of the planar coil in the third conductor layer and is also wired along the second direction opposite to the first direction to form a mirror arrangement of the planar coil in the third conductor layer and the planar coil in the fourth conductor layer.

6. A coreless PCB stator winding for an axial flux motor according to claim 5, characterized in that: The via array includes a blind via array and a through via array. Among them, the blind via array is located in the wide copper busbar area, and the blind via array is a plurality of blind vias distributed in a two-dimensional array. The planar coil in the first conductor layer and the planar coil in the second conductor layer are connected through the blind via array provided on the first annular substrate; the planar coil in the third conductor layer and the planar coil in the fourth conductor layer are connected through the blind via array provided on the second annular substrate; The through via array is located in the transfer commutation area, and the through via array is a plurality of through vias distributed in an arc array. The planar coil in the second conductor layer and the planar coil in the third conductor layer are connected through the through via array to transfer the wire from the second conductor layer to the third conductor layer.

7. A coreless PCB stator winding for an axial flux motor according to claim 6, characterized in that: Among the six virtual slot positions corresponding to a pair of magnetic poles, the conductor active edges of the planar coils in the U-phase winding, V-phase winding, and W-phase winding are arranged circumferentially in a predetermined phase sequence of U, V, W and alternately occupy the six virtual slot positions.

8. A stator assembly for an axial flux motor, characterized in that: The stator assembly includes a thermal insulation layer, a metal heat dissipation frame, and a coreless PCB stator winding for an axial flux motor according to any one of claims 1-7; The coreless PCB stator winding is bonded to the metal heat dissipation frame through the thermal insulation layer.

9. An axial flux motor, characterized in that: It includes a rotor assembly and a stator assembly, and the stator assembly is a stator assembly for an axial flux motor according to claim 8; The rotor assembly includes a rotor disk and permanent magnets provided on the rotor disk, and the conductor active edges of the coreless PCB stator winding are located in the effective flux cutting area corresponding to the permanent magnets.

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