A stator core with fractal multi-stage flow channels on teeth and a permanent magnet motor

Abstract

The present invention discloses a stator core with fractal multi-stage flow channels on its teeth, belonging to the field of motor cooling technology. The stator core comprises: multiple flow channel sections distributed axially in sequence; a flow channel opening is provided at the intersection of the center extension line of each stator tooth and the outer circumference of the median cross-section in each flow channel section, and the flow channel section comprises two sub-flow channel sections that are mirror-symmetrical about the median cross-section; each sub-flow channel section is provided with a primary flow channel extending from the flow channel opening to the tooth yoke junction in the radial direction of each stator tooth, and second to Nth-stage flow channels gradually extending from the tooth yoke junction to the tooth tip; in the second to Nth-stage flow channels, the previous primary flow channel is connected to two subsequent primary flow channels; the final flow channels of two adjacent sub-flow channel sections belonging to the same flow channel section are not directly connected, but are connected by an axial flow channel at the tooth tip in two adjacent sub-flow channel sections belonging to different flow channel sections. The present invention can effectively solve the problem of uneven axial heat dissipation in the motor and fully cool the stator core and windings.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor cooling, and more particularly, relates to a stator core and a permanent magnet motor having fractal multi-stage flow channels on the teeth. Background Art

[0002] Aviation electrification and the development of more-electric aircraft have significantly simplified aircraft system architecture, reduced fuel consumption, and improved engine efficiency. With the widespread installation of large-capacity electrical equipment, the demand for onboard electrical energy in military and civilian more-electric aircraft has increased significantly. Under strict weight constraints and integrated design, generator systems, as core electrical components of aircraft, have assumed an even more crucial role in the electrification revolution. Large-capacity, even megawatt-class, high-power-density aircraft generator systems are key to the development of aviation electrification for large and medium-sized aircraft. In permanent magnet motor topologies, high-speed, high-electromagnetic load designs are often employed to increase motor power density. However, this high-speed, high-electromagnetic load design significantly increases internal heat sources such as copper and iron losses, and their distribution becomes more uneven. Furthermore, the high-temperature and low-pressure operating conditions of more-electric aircraft exacerbate heat dissipation conditions. Large-capacity, ultra-high-power-density aircraft generators face exceptionally severe thermal management challenges. Therefore, new, efficient cooling technologies for high-loss active components, such as motor windings and cores, have become a key technology in the design of megawatt-class, high-power-density aircraft generators.

[0003] At present, the base frequency of large-capacity aircraft generators can reach above 1000Hz, and the current density can reach 20A / mm 2 Above, the average copper loss density can reach 1×10 7 W / m 3 , the average iron loss density can reach 5×10 6 W / m 3 Excessive temperature rise in motors under extremely high loss density will not only cause aging of motor materials and shorten the life of the motor; in severe cases, it may even cause accidents such as short circuit and burning of the motor windings. Therefore, how to improve heat dissipation performance is the key to increasing the power density of large-capacity aircraft generators. Compared with water, oil has good insulation properties. As a cooling medium, it can directly contact the surface of the effective parts of the motor, such as the windings and the iron core, greatly reducing the thermal resistance between the heat source and the cooling medium. Therefore, oil cooling has been widely used in high-power density motors.

[0004] At present, the mainstream cooling technology used in large-capacity aircraft generators is a combination of stator casing oil circulation and winding end oil injection. However, in this cooling technology, the cooling medium generally only contacts the outer surface of the stator core and the surface of the winding end, resulting in a limited heat dissipation area. In addition, the heat dissipation path from the stator core heat source, i.e., the stator teeth, to the cooling medium is long, making it difficult to meet the heat dissipation requirements of higher power density.

[0005] The new stator oil immersion cooling technology completely immerses the heat-generating components of the motor stator core and windings in cooling oil, which can achieve a more efficient cooling effect. In the patent document with application publication number CN115459501A, a semi-sealed hybrid cooling high-speed permanent magnet motor is disclosed, such as Figure 1 As shown, it includes a stator core I1, a slot bottom flow channel I11, an inner slot flow channel I12, a stator winding I2, a support frame I3, a special-shaped stator sheath I4, a casing I5, an oil outlet hole I51, an axial flow channel I52, a heat dissipation fin I53, a driving end cover I6, an oil inlet hole I61, an annular distribution groove I62, an additional supporting cylinder wall I63, a non-driving end cover I7, a sealing ring I8, and an airtight electrical connector I9. This solution constructs a slot bottom flow channel between the bottom arc surface of the stator core and the supporting frame, and constructs an in-slot flow channel between the supporting frame, the stator winding and the stator heterogeneous sheath. Combined with liquid cooling and natural cooling of the casing, the overall cooling structure has the advantages of compact structure and high reliability. However, the slot bottom flow channel and the in-slot flow channel have a good cooling effect on the motor winding, but are far away from the heat source of the motor stator core teeth. The thermal resistance on the heat transfer path is large, and the stator teeth cannot be efficiently cooled. At the same time, the support structure between the stator yoke and the winding occupies additional slot area, which is not conducive to the improvement of power density.

[0006] In the patent document with application publication number CN111555486A, a motor stator cooling structure and a motor are disclosed, such as Figure 2 As shown, it includes a stator core II2, a first cover plate II31; a first plug-in platform II311, a second cover plate II41, a second plug-in platform II411, and a baffle II5. This solution has two covers at both axial ends of the stator core, and multiple slots and baffles arranged circumferentially. The first cover, the second cover, the baffles, and the multiple slots form a cooling channel extending circumferentially along the stator core, isolating the coolant from the motor rotor. This solves the problem of motor energy loss caused by the rotation of the motor rotor stirring the coolant, and improves the power density of the motor. However, the structure is relatively complex, and while the cooling system has a good cooling effect on the winding ends and the stator core yoke, the temperature of the windings in the slots and the core teeth is relatively high.

[0007] In general, existing oil immersion cooling usually sets axial flow channels at the stator slots and yokes. The temperature difference between the oil channel inlet and outlet is large, the axial heat dissipation effect of the motor is uneven, and the distance between the heat source and the cooling medium is still far. The heat dissipation performance still cannot meet the heat dissipation requirements of extremely high loss density. Summary of the Invention

[0008] In response to the defects of the existing technology and the need for improvement, the present invention provides a stator core and a permanent magnet motor with fractal multi-stage flow channels in the teeth, the purpose of which is to effectively solve the problem of uneven axial heat dissipation of the motor and achieve sufficient cooling of the stator core and windings.

[0009] To achieve the above object, according to one aspect of the present invention, there is provided a stator core having a tooth portion with a fractal multi-stage flow channel, comprising a plurality of flow channel segments sequentially distributed along the axial direction;

[0010] In the flow channel section, a flow channel opening is provided at the intersection of the center extension line of each stator tooth and the outer circumference of the median section, and the flow channel section includes two sub-flow channel sections that are mirror-symmetrical about the median section; the median section is the section located in the middle of the axial direction;

[0011] In the sub-flow channel section, N levels of flow channels are provided in the radial direction of each stator tooth, distributed sequentially from the yoke to the tooth. One first-level flow channel is provided, one end of which is connected to the corresponding flow channel opening and the other end is located at the intersection of the tooth and yoke. One second-level flow channel is provided, which is connected to the first-level flow channel at the intersection of the tooth and yoke. From the second to the Nth level flow channels, the number of flow channels in each level is twice the number of flow channels in the previous level, and in two adjacent levels of flow channels, the previous level flow channel is connected to two flow channels in the next level.

[0012] The final flow passages in two adjacent sub-flow passage sections belonging to the same flow passage section are not directly connected, and the final flow passages in two adjacent sub-flow passage sections belonging to different flow passage sections are connected via an axial flow passage at the tooth tip;

[0013] Wherein, N is a positive integer greater than or equal to 2.

[0014] Furthermore, among the second-stage flow channels to the Nth-stage flow channels, in two adjacent stages of flow channels, the width of the previous stage of flow channels is twice the width of the next stage of flow channels.

[0015] Furthermore, in each flow channel section, the last-stage flow channel is the longest, and the last-stage flow channels are evenly distributed in the axial direction.

[0016] Furthermore, the first-stage flow channel is a stepped flow channel.

[0017] Furthermore, the first-stage flow channel is a three-stage stepped flow channel.

[0018] Furthermore, the value of N is 2, 3 or 4.

[0019] In some optional embodiments, N=4;

[0020] Moreover, the sub-flow channel segments include, in order along the axial direction: a flow channel mouth iron core segment, a first-level four-level flow channel iron core segment, a first-level three-level flow channel iron core segment, a yoke flow channel mouth three-level flow channel iron core segment, a second-level three-level flow channel iron core segment, a second-level four-level flow channel iron core segment, a second-level three-level flow channel iron core segment, a third-level flow channel iron core segment, a fourth-level flow channel iron core segment, and a tooth tip flow channel mouth iron core segment;

[0021] The runner opening core segment has a runner opening arranged at the intersection of the outer circumference thereof and the extension line of the center of each stator tooth;

[0022] The first-level and fourth-level flow channel core segments have a yoke portion provided with a drainage hole corresponding to each stator tooth, and each tooth portion is provided with a flow channel extending from the second position to the tooth tip; each drainage hole in the first-level and fourth-level flow channel core segments partially overlaps with the corresponding flow channel opening in the flow channel opening core segment;

[0023] The first-stage and third-stage flow channel core segments have drainage holes at the junction of the tooth yokes of each stator tooth, a flow channel extending from a first position to a second position on each stator tooth, and a flow channel opening at the tooth tip of each stator tooth; each drainage hole in the first-stage and third-stage flow channel core segments partially overlaps with the corresponding drainage hole in the first-stage and fourth-stage flow channel core segments;

[0024] The three-stage runner core section of the yoke runner opening has runner openings at the tooth yoke junction and tooth tip of each stator tooth, and a runner extending from a first position to a second position is provided on each stator tooth;

[0025] The secondary and tertiary flow channel core segments are provided with a flow channel extending from the tooth yoke junction to the second position on each stator tooth, and a flow channel opening is provided on the tooth tip of each stator tooth;

[0026] The two-stage four-stage flow channel core segment has a flow channel on each stator tooth extending from the tooth yoke junction to the first position, and a flow channel extending from the second position to the tooth tip;

[0027] A secondary flow channel core segment is provided on each stator tooth thereof with a flow channel extending from the tooth yoke junction to the first position, and a flow channel opening is provided at the tooth tip of each stator tooth;

[0028] A three-stage flow channel core segment, wherein each stator tooth is provided with a flow channel extending from a first position to a second position, and a flow channel opening is provided at the tooth tip of each stator tooth;

[0029] A four-stage flow channel core segment, each stator tooth of which is provided with a flow channel extending from the second position to the tooth tip;

[0030] The tooth tip flow channel iron core section has a flow channel at the tooth tip of each stator tooth;

[0031] Among them, in each stator tooth, the tooth yoke junction, the first position, the second position, and the tooth tip are arranged in sequence.

[0032] In some optional embodiments, N=3;

[0033] Moreover, the sub-flow channel segment includes: a flow channel opening core segment, a first-stage drainage core segment, a second-stage drainage core segment, a yoke flow channel opening core segment, a second-stage flow channel core segment, a connecting core segment, a third-stage flow channel core segment, and a tooth tip flow channel opening core segment, which are sequentially arranged along the axial direction.

[0034] The runner opening core segment has a runner opening arranged at the intersection of the outer circumference thereof and the extension line of the center of each stator tooth;

[0035] The first-stage drainage core segment has a yoke portion provided with drainage holes corresponding to the stator teeth; each drainage hole in the first-stage drainage core segment overlaps with the corresponding flow channel opening portion in the flow channel opening core segment;

[0036] The second-stage drainage core segment has drainage holes at the junction of the tooth yoke of each stator tooth; and the tooth portion is provided with a flow channel extending from the third position to the tooth tip; each drainage hole in the second-stage drainage core segment partially overlaps with the corresponding drainage hole in the first-stage drainage core segment;

[0037] The yoke core section has runner openings, where the tooth-yoke junction and tooth tip of each stator tooth are provided with runner openings, and a connecting hole is provided at the third position of each stator tooth;

[0038] The secondary flow channel iron core segment has a flow channel on each stator tooth extending from the tooth yoke junction to the third position, and a flow channel opening is provided at the tooth tip of each stator tooth;

[0039] The connecting core segment has a connecting hole at a third position on each stator tooth, and a flow channel opening at the tooth tip of each stator tooth;

[0040] A three-stage flow channel core segment, each stator tooth of which is provided with a flow channel extending from a third position to a tooth tip;

[0041] The tooth tip flow channel iron core section has a flow channel at the tooth tip of each stator tooth;

[0042] Among them, in each stator tooth, the third position is located between the tooth yoke junction and the tooth tip.

[0043] In some optional embodiments, N=2;

[0044] Furthermore, the sub-flow channel segment includes: a flow channel opening core segment, a first-stage drainage core segment, a second-stage drainage core segment, a yoke flow channel opening core segment, a second-stage flow channel core segment, and a tooth tip flow channel opening core segment, which are sequentially arranged along the axial direction.

[0045] The runner opening core segment has a runner opening arranged at the intersection of the outer circumference thereof and the extension line of the center of each stator tooth;

[0046] The first-stage drainage core segment has a yoke portion provided with drainage holes corresponding to the stator teeth; each drainage hole in the first-stage drainage core segment overlaps with the corresponding flow channel opening portion in the flow channel opening core segment;

[0047] The second-stage drainage core segment has drainage holes at the junction of the tooth yokes of each stator tooth; each drainage hole in the second-stage drainage core segment partially overlaps with the corresponding drainage hole in the first-stage drainage core segment;

[0048] The yoke runner core section has a runner opening at the junction of each stator tooth and the yoke; each runner opening in the yoke runner core section partially overlaps with the corresponding drainage hole in the second-stage drainage core section;

[0049] The secondary flow channel core segment has a flow channel on each stator tooth extending from the tooth yoke junction to the tooth portion;

[0050] The tooth tip flow channel opening iron core section has a flow channel opening at the tooth tip of each stator tooth.

[0051] According to another aspect of the present invention, a permanent magnet motor is provided, comprising the stator core having the fractal multi-stage flow passages on the teeth as described above.

[0052] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0053] (1) The stator core provided by the present invention has a fractal multi-stage flow channel in the tooth portion, which is divided into multiple flow channel segments along the axial direction. A flow channel opening corresponding to each stator tooth is provided on the outer circumference of the middle part of each flow channel segment. In addition, a symmetrical flow channel structure is designed at the position corresponding to each stator tooth, in which the flow from the flow channel opening to the tooth tip is divided step by step. Under this flow channel structure, the flow channels of each level are distributed axially in the corresponding flow channel segment. In addition, in the same flow channel segment, the last-stage flow channels in the two symmetrical sub-flow channel segments are not directly connected, but belong to different flow channel segments. The last-stage flow channels in adjacent sub-flow channels converge at the tooth tip. Based on this structural design, the inlet core segment and the outlet core segment are alternately arranged along the axial direction, and the cooling medium is injected into the flow channel opening in the inlet core segment. The cooling medium will flow inward step by step along the fractal flow channel structure in the inlet core segment. After flowing to the tooth tip, it will converge in the axial direction and gradually converge and flow outward through the fractal flow channel structure in the adjacent outlet core segment, and finally flow out through the flow channel opening of the outlet core segment, thus forming a multi-stage, multi-inlet, and multi-outlet cooling flow channel structure. Based on this cooling channel structure, on the one hand, the axial flow path of the cooling medium is shortened, so that the stator can be evenly cooled in the axial direction, effectively solving the problem of uneven axial heat dissipation; on the other hand, the cold medium flow channel is mainly integrated into the stator teeth, which increases the contact area between the cooling medium and the heat source of the stator internal core, and also reduces the distance between the winding heat source and the cooling medium. In addition, the turbulence of the cooling medium flow is enhanced, the thermal boundary layer of the microchannel wall is effectively destroyed, and the convective heat transfer coefficient is significantly increased, thereby achieving sufficient cooling of the stator core and winding.

[0054] (2) The stator core provided by the present invention has a fractal multi-stage flow channel in the tooth portion. Among the second to Nth stage flow channels, the width of the previous stage flow channel in two adjacent stages is twice the width of the next stage flow channel, which facilitates the cooling medium to be dispersed from the previous stage to the next stage, and to be gathered from the next stage to the previous stage.

[0055] (3) The stator core provided by the present invention has a fractal multi-stage flow channel in the tooth portion, and the number of the final-stage flow channels is the largest. In its preferred embodiment, the final-stage flow channel is the longest among the flow channel sections, and the final-stage flow channels are evenly distributed in the axial direction, thereby further improving the uniformity of axial heat dissipation.

[0056] (4) The present invention provides a stator core having a fractal multi-stage flow channel in the tooth portion. In a preferred embodiment, the first-stage flow channel from the sub-flow channel opening to the tooth yoke junction is designed as a stepped flow channel. This can reduce the impact of the first-stage flow channel on the magnetic circuit of the stator core yoke, thereby avoiding the impact on electromagnetic performance caused by the interruption of the yoke magnetic circuit by the first-stage flow channel. In a further preferred embodiment, the first-stage flow channel is designed as a three-stage stepped flow channel. This can simplify the structural complexity of the core segment covered by the first-stage flow channel while avoiding the impact on electromagnetic performance.

[0057] (5) The stator core provided by the present invention has a fractal multi-stage flow channel in its tooth portion. In its preferred embodiment, in the fractal flow channel structure, the number of flow channel stages is specifically designed to be 2, 3 or 4, thereby being able to balance the heat dissipation effect and structural complexity to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a schematic diagram of an existing semi-sealed hybrid cooling high-speed permanent magnet motor;

[0059] Figure 2 The figure is a schematic diagram of an existing motor stator cooling structure and a motor;

[0060] Figure 3 A schematic diagram of the structure of a stator core with fractal multi-stage flow channels on the teeth provided by the present invention;

[0061] Figure 4 A schematic diagram of the cooling medium flow path in a stator core having fractal multi-stage flow channels on the teeth provided in Example 1 of the present invention;

[0062] Figure 5 A schematic diagram of the structure of a sub-flow channel section provided in Example 1 of the present invention;

[0063] Figure 6 A schematic diagram of the structure of the runner mouth core segment provided in Example 1 of the present invention;

[0064] Figure 7 A schematic diagram of the structure of the first-stage and fourth-stage runner core segments provided in Example 1 of the present invention;

[0065] Figure 8 A schematic diagram of the structure of the first and third level runner core segments provided in Example 1 of the present invention;

[0066] Figure 9 A schematic diagram of the structure of the three-stage runner core section of the yoke runner outlet provided in Example 1 of the present invention;

[0067] Figure 10 A schematic diagram of the structure of the secondary and tertiary runner core segments provided in Example 1 of the present invention;

[0068] Figure 11 A schematic diagram of the structure of the secondary and fourth-stage runner core segments provided in Example 1 of the present invention;

[0069] Figure 12 A schematic diagram of the structure of the secondary runner core segment provided in Example 1 of the present invention;

[0070] Figure 13 A schematic diagram of the structure of the three-stage runner core segment provided in Example 1 of the present invention;

[0071] Figure 14 A schematic diagram of the structure of a four-stage runner core segment provided in Example 1 of the present invention;

[0072] Figure 15 A schematic diagram of the structure of the core section of the tooth tip runner opening provided in Example 1 of the present invention;

[0073] Figure 16 A schematic diagram of the structure of a sub-flow channel section provided in Example 1 of the present invention;

[0074] Figure 17 A schematic diagram of the cooling medium flow path in a stator core having fractal multi-stage flow channels on the teeth provided in Example 2 of the present invention;

[0075] Figure 18 A schematic diagram of the structure of a sub-flow channel section provided in Example 2 of the present invention;

[0076] Figure 19 A schematic diagram of the structure of a sub-flow channel section provided in Example 2 of the present invention;

[0077] Figure 20 A schematic diagram of the cooling medium flow path in a stator core having fractal multi-stage flow channels on the teeth provided in Example 3 of the present invention;

[0078] Figure 21 A schematic diagram of the structure of a sub-flow channel section provided in Example 3 of the present invention;

[0079] Figure 22 A schematic diagram of the structure of a sub-flow channel section provided in Example 3 of the present invention;

[0080] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0081] I1 - stator core; I11 - slot bottom flow channel, I12 - slot inner flow channel; I2 - stator winding; I3 - support frame; I4 - special-shaped stator jacket; I5 - housing; I51 - oil outlet, I52 - axial flow channel, I53 - cooling fins; I6 - drive end cover; I61 - oil inlet, I62 - annular distribution groove, I63 - additional support cylinder wall; I7 - non-drive end cover; I8 - sealing ring; I9 - airtight electrical connector;

[0082] II2-stator core; II31-first cover plate; II311-first plug-in platform, II41-second cover plate; II411-second plug-in platform; II5-blocking piece;

[0083] 101- runner mouth core segment, 102- first-level four-stage runner core segment, 103- first-level three-stage runner core segment, 104- yoke runner mouth three-stage runner core segment, 105- second-level three-stage runner core segment, 106- second-level four-stage runner core segment, 107- second-level runner core segment, 108- three-stage runner core segment, 109- four-stage runner core segment, 110- tooth tip runner mouth core segment;

[0084] 201- runner core segment, 202- first-stage drainage core segment, 203- second-stage drainage core segment, 204- yoke runner core segment, 205- second-stage runner core segment, 206- connecting core segment, 207- tertiary runner core segment, 208- tooth tip runner core segment;

[0085] 301- runner mouth core segment, 302- first stage drainage core segment, 303- second stage drainage core segment, 304- yoke runner mouth core segment, 305- second stage runner core segment, 306- tooth tip runner mouth core segment. DETAILED DESCRIPTION

[0086] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0087] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0088] In order to solve the technical problems of uneven axial heat dissipation and inability to fully cool the stator core and windings in the existing motor stator cooling structure, the present invention provides a stator core and a permanent magnet motor with fractal multi-stage flow channels on the teeth. The overall concept is to divide the stator core into multiple sections along the axial direction, design multi-stage fractal flow channels on the teeth of each section, and through a connected design, the stator as a whole has multiple cooling medium inlets and multiple cooling medium outlets along the axial direction, thereby improving the axial heat dissipation uniformity. The fractal flow channel design on the teeth can fully cool the stator core, shorten the distance between the winding and the cooling medium, and fully cool the winding.

[0089] Based on the above concept, the present invention provides a stator core having a fractal multi-stage flow channel on the teeth, such as Figure 3 As shown, it includes a plurality of flow channel segments distributed in sequence along the axial direction;

[0090] In the flow channel section, a flow channel opening is provided at the intersection of the center extension line of each stator tooth and the outer circumference of the median section, and the flow channel section includes two sub-flow channel sections that are mirror-symmetrical about the median section; the median section is the section located in the middle of the axial direction;

[0091] In the sub-flow channel section, N levels of flow channels are provided in the radial direction of each stator tooth, distributed sequentially from the yoke to the tooth. One first-level flow channel is provided, one end of which is connected to the corresponding flow channel opening and the other end is located at the intersection of the tooth and yoke. One second-level flow channel is provided, which is connected to the first-level flow channel at the intersection of the tooth and yoke. From the second to the Nth level flow channels, the number of flow channels in each level is twice the number of flow channels in the previous level, and in two adjacent levels of flow channels, the previous level flow channel is connected to two flow channels in the next level.

[0092] The final flow passages in two adjacent sub-flow passage sections belonging to the same flow passage section are not directly connected, and the final flow passages in two adjacent sub-flow passage sections belonging to different flow passage sections are connected via an axial flow passage at the tooth tip;

[0093] Wherein, N is a positive integer greater than or equal to 2.

[0094] Based on the above structural design, the inlet core segments and the outlet core segments are alternately arranged along the axial direction, and the cooling medium is injected into the flow channel openings in the inlet core segments. The cooling medium will flow inward step by step along the fractal flow channel structure in the inlet core segments. After flowing to the tooth tip, it will be gathered in the axial direction and gradually gathered through the fractal flow channel structure in the adjacent outlet core segments and flow outward, finally flowing out through the flow channel openings of the outlet core segments. This forms a multi-stage, multi-inlet, and multi-outlet cooling flow channel structure. On the one hand, the axial flow path of the cooling medium is shortened, so that the stator can be evenly cooled in the axial direction, effectively solving the problem of uneven axial heat dissipation. On the other hand, the cooling medium flow channel is mainly integrated into the stator teeth, which increases the contact area between the cooling medium and the stator internal core heat source, and also reduces the distance between the winding heat source and the cooling medium. In addition, the turbulence of the cooling medium flow is enhanced, the thermal boundary layer on the microchannel wall is effectively destroyed, and the convective heat transfer coefficient is significantly increased, thereby achieving sufficient cooling of the stator core and winding. On this basis, the present invention can further make the following improvements.

[0095] In order to facilitate the cooling medium to be dispersed from the previous stage to the next stage when flowing from the outside to the inside, and to be gathered from the next stage to the previous stage when flowing out from the inside to the outside, in this embodiment, among the second-stage flow channels to the N-stage flow channels, the width of the previous stage flow channel in two adjacent stages is twice the width of the next stage flow channel, so as to facilitate the cooling medium to be dispersed from the previous stage to the next stage, and to be gathered from the next stage to the previous stage.

[0096] Considering that the number of the final flow channels is the largest in each flow channel section, in order to further improve the axial heat dissipation uniformity of the motor, the present invention preferably sets the final flow channel to be the longest in each flow channel section and the final flow channels to be evenly distributed in the axial direction.

[0097] To minimize impact on the motor's electromagnetic performance, in this embodiment, the first-stage flow channel from the sub-flow channel opening to the tooth-yoke junction is designed as a stepped flow channel. This minimizes the first-stage flow channel's impact on the stator core yoke's magnetic circuit, ensuring that the magnetic circuit is not interrupted by the first-stage flow channel at the yoke. In practice, the number of steps in the first-stage flow channel can be adjusted based on the yoke thickness of the motor's stator core. Taking into account both the manufacturing difficulty and the impact on electromagnetic performance, the present invention preferably employs a three-step structure for the first-stage flow channel.

[0098] In actual applications, the number of flow channel stages in each flow channel section, the length and width of each flow channel, etc. can be set accordingly according to the actual size of the motor stator core, heat dissipation requirements, structural design difficulty, etc. The present invention has found through experiments and practical applications that it is more reasonable to design the number of flow channel stages in the fractal flow channel structure of each flow channel section to 2, 3 or 4, which can balance the heat dissipation effect and structural complexity to the greatest extent.

[0099] After determining the number of flow channel stages, the present invention designs different types of silicon steel sheets based on the specific structure of the fractal flow channels. These different types of silicon steel sheets are stacked according to a specific pattern to form flow channel segments that integrate the specific flow channel structure. The present invention's design of flow channel segments for a specific number of flow channel stages is based on the following principles: microchannels are designed to minimize interruption of the motor's magnetic circuit, and microchannels are positioned close to heat sources to maximize heat dissipation area.

[0100] The following describes the specific structures of the stator cores of the two-stage flow channel, the three-stage flow channel and the four-stage flow channel in combination with specific embodiments when the two-stage stepped first-stage flow channel is adopted.

[0101] Example 1:

[0102] A stator core with a fractal multi-stage flow channel on the teeth. In this embodiment, a total of four levels of flow channels are provided, and the cooling medium flow path inside the stator core is as follows: Figure 4 As shown, the cooling medium flows in from multiple inlets, flows along the inlets to the first-level stepped flow channel, the second, third, and fourth-level micro-flow channels, and flows radially inward at the stator core tooth yoke, while flowing axially toward the nearest outlets on both sides. If the nearest outlet is located in the middle of the motor, the cooling medium flows through the outlet to the fourth, third, and second-level micro-flow channels and the first-level stepped flow channel and flows radially outward from the outer surface of the stator core; if the nearest outlet is located at both ends of the motor, the cooling medium flows out through the tooth tip flow channel outlet.

[0103] In each flow channel segment, the sub-flow channel segment structure on one side is as follows Figure 5 As shown. Since the embedded integrated design of micro-channels will make the structure of the core more complicated, this embodiment takes into account the actual industrial processing, in order to minimize the process cost and improve the industrialization potential, based on the limitations of silicon steel sheet processing technology and the characteristics of core processing, and in accordance with the principle that the micro-channel design does not block the motor magnetic circuit as much as possible, the micro-channel is located close to the heat source, and the heat dissipation area is increased, ten different stator tooth yoke silicon steel sheets are designed for the stator core shaft radial fractal micro-channel heat sink according to its axial space layout, and ten stator core segments are formed accordingly after stacking, as shown. Figures 6 to 15 As shown. Ten types of stator core segments are arranged and laminated in a specific combination to form a single-sided sub-flow channel segment, and two sub-flow channel segments are arranged in a mirror-symmetrical manner to form a complete flow channel segment; multiple flow channel segments are arranged in sequence along the axial direction to form the entire stator core. Specifically, the sub-flow channel segments include in sequence along the axial direction: a flow channel mouth core segment 101, a first-level four-level flow channel core segment 102, a first-level three-level flow channel core segment 103, a yoke flow channel mouth three-level flow channel core segment 104, a second-level three-level flow channel core segment 105, a second-level four-level flow channel core segment 106, a second-level flow channel core segment 107, a second-level four-level flow channel core segment 106, a second-level three-level flow channel core segment 105, a third-level flow channel core segment 108, a fourth-level flow channel core segment 109, and a tooth tip flow channel mouth core segment 110;

[0104] The structure of the runner core segment 101 is as follows: Figure 6 As shown, a flow channel opening is provided at the intersection of the outer circumference and the extension line of the center of each stator tooth;

[0105] The structure of the first-level and fourth-level runner core segments 102 is as follows: Figure 7 As shown, the yoke is provided with drainage holes corresponding to the stator teeth, and each tooth is provided with a flow channel extending from the second position to the tooth tip; each drainage hole in the first and fourth level flow channel core segments 102 partially overlaps with the corresponding flow channel opening in the flow channel opening core segment 101;

[0106] The structure of the first and third level runner core segments 103 is as follows: Figure 8 As shown, a drainage hole is provided at the junction of the tooth yoke of each stator tooth, a flow channel extending from a first position to a second position is provided on each stator tooth, and a flow channel opening is provided at the tooth tip of each stator tooth; each drainage hole in the first and third level flow channel core segments 103 partially overlaps with the corresponding drainage hole in the first and fourth level flow channel core segments 102;

[0107] The structure of the three-stage runner core section 104 at the yoke runner opening is as follows: Figure 9 As shown, the tooth yoke junction and tooth tip of each stator tooth are provided with a flow channel opening, and each stator tooth is provided with a flow channel extending from a first position to a second position;

[0108] The structure of the secondary and tertiary runner core segments 105 is as follows: Figure 10 As shown, each stator tooth is provided with a flow channel extending from the tooth yoke junction to the second position, and the tooth tip of each stator tooth is provided with a flow channel opening;

[0109] The structure of the secondary and quaternary runner core segments 106 is as follows: Figure 11 As shown, each stator tooth is provided with a flow channel extending from the tooth yoke junction to the first position, and a flow channel extending from the second position to the tooth tip;

[0110] The structure of the secondary runner core segment 107 is as follows Figure 12 As shown, each stator tooth is provided with a flow channel extending from the tooth yoke junction to the first position, and the tooth tip of each stator tooth is provided with a flow channel opening;

[0111] The structure of the three-stage runner core segment 108 is as follows Figure 13 As shown, each stator tooth is provided with a flow channel extending from a first position to a second position, and a flow channel opening is provided at the tooth tip of each stator tooth;

[0112] The structure of the four-stage runner core segment 109 is as follows Figure 14 As shown, each stator tooth is provided with a flow channel extending from the second position to the tooth tip;

[0113] The structure of the tooth tip runner core segment 110 is as follows: Figure 15 As shown, the tip of each stator tooth is provided with a flow channel opening;

[0114] Among them, in each stator tooth, the tooth yoke junction, the first position, the second position, and the tooth tip are arranged in sequence.

[0115] The sub-flow channel segment structure assembled based on the above ten core segments is as follows: Figure 16 As shown. Ten types of stator core segments are arranged and stacked in a designed combination to form a single set of axial-radial fractal microchannel heat sinks for the stator core tooth yoke. A multi-inlet and multi-outlet fractal microchannel combination is designed in combination with the axial length of the motor and the heat dissipation requirements. Multiple sets of axial-radial fractal microchannel core segments of the stator core tooth yoke are arranged and stacked to form an integral stator core. The fractal multi-stage microchannel solution designed for the stator core tooth yoke along the axial radial direction in this embodiment helps to further destroy the thermal boundary layer of the microchannel wall and improve the cooling effect, and the multi-inlet and multi-outlet design helps to improve the problem of uneven axial heat dissipation of the motor. The inlet flow direction fractal microchannel and the outlet flow direction fractal microchannel have exactly the same structure, except that the cooling medium flows in opposite directions. This design method is conducive to the modular design of the motor.

[0116] In order to make the inner wall of the flow channel in each core segment in the first-level flow channel fit tightly, in this embodiment, the radially outermost end is the head end, the radially innermost end is the tail end, the flow channel mouth end of the structure of the flow channel mouth core segment is an arc, the head and tail ends of the drainage holes set on the yoke in the first-level and fourth-level flow channel core segments are both arcs, and the head and tail ends of the drainage holes at the junction of the teeth and yoke in the first-level and third-level flow channel core segments are both arcs; the center of the tail end arc of the drainage hole in the flow channel mouth core segment coincides with the center of the head end arc of the drainage hole in the first-level and fourth-level flow channel core segments, and the apertures are equal; the center of the tail end arc of the drainage hole in the first-level and fourth-level flow channel core segments coincides with the center of the head end arc of the drainage hole in the first-level and third-level flow channel core segments, and the apertures are equal.

[0117] In summary, this embodiment provides a high-capacity, ultra-high power density, aviation-grade motor stator core tooth yoke axial-radial fractal multi-stage, multi-inlet and outlet microchannel internal cooling structure. This design can be constructed based on traditional silicon steel sheet processing methods or 3D printing technology to construct a new internal cooling structure for the stator core tooth yoke axial-radial fractal multi-stage microchannel. The heat sink is integrated with the motor stator core to achieve sufficient cooling of the stator core and windings. This stator core microchannel internal cooling structure is suitable for both fuel injection cooling and oil immersion cooling of aviation fuel and aviation lubricating oil, as well as internal cooling of other insulating cooling media such as air, helium, and hydrogen. This embodiment designs multiple inlets and outlets based on the fractal multi-stage microchannel internal cooling structure. After the cooling medium enters the stator core through one of the inlets, it flows axially toward the nearest outlet at both ends of the core, while flowing radially inward or radially outward along the multi-stage fractal flow channels of the core teeth, thereby forming a micro heat sink for the core tooth yoke. This cooling architecture significantly reduces the heat source's heat dissipation path, significantly increases the heat dissipation area and heat transfer coefficient, and provides a very strong cooling effect for microchannel internal cooling. This embodiment effectively solves the problems of heat dissipation difficulties and uneven axial heat dissipation in the extremely high loss density of the core and windings of large-capacity, ultra-high power density aviation motors.

[0118] Example 2:

[0119] A stator core with a fractal multi-stage flow channel on the teeth. In this embodiment, a total of three levels of flow channels are provided, and the cooling medium flow path inside the stator core is as follows: Figure 17 As shown, the cooling medium flows in from multiple inlets, flows along the inlets to the first-level stepped flow channel, the second-level and third-level micro-flow channels, and flows radially inward at the stator core tooth yoke, while flowing axially toward the nearest outlets on both sides. If the nearest outlet is located in the middle of the motor, the cooling medium flows through the outlet to the third-level and second-level micro-flow channels and the first-level stepped flow channel and flows radially outward from the outer surface of the stator core; if the nearest outlet is located at both ends of the motor, the cooling medium flows out through the tooth tip flow channel outlet.

[0120] In each flow channel segment, the sub-flow channel segment structure on one side is as follows Figure 18 As shown. Based on the same considerations as in Example 1, this embodiment follows the principle of minimizing the blocking of the motor magnetic circuit by designing the microchannel, positioning the microchannel close to the heat source, and increasing the heat dissipation area. A total of eight different stator tooth yoke silicon steel sheets are designed for the stator core shaft radial fractal microchannel heat sink according to its axial spatial layout. After stacking, eight stator core segments are correspondingly formed. The eight stator core segments are arranged and stacked in a specific combination to form a single-sided sub-channel segment. Two sub-channel segments are arranged in a mirror-symmetrical manner to form a complete channel segment. Multiple channel segments are arranged in sequence along the axial direction to form the entire stator core.

[0121] Specifically, the sub-flow channel segment includes: a flow channel opening core segment 201, a first-stage drainage core segment 202, a second-stage drainage core segment 203, a yoke flow channel opening core segment 204, a second-stage flow channel core segment 205, a connecting core segment 206, a third-stage flow channel core segment 207, and a tooth tip flow channel opening core segment 208.

[0122] The runner opening core segment 201 has a runner opening provided at the intersection of its outer circumference and the extension line of the center of each stator tooth;

[0123] The first-stage drainage core segment 202 has a yoke portion provided with drainage holes corresponding to the stator teeth; each drainage hole in the first-stage drainage core segment 202 partially overlaps with the corresponding flow channel opening in the flow channel opening core segment 201;

[0124] The second-stage drainage core segment 203 has drainage holes at the junction of the tooth yoke of each stator tooth; and the tooth portion is provided with a flow channel extending from the third position to the tooth tip; each drainage hole in the second-stage drainage core segment 203 partially overlaps with the corresponding drainage hole in the first-stage drainage core segment 202;

[0125] The yoke core segment 204 has a runner opening at the tooth-yoke junction and the tooth tip of each stator tooth, and a connecting hole at the third position of each stator tooth;

[0126] The secondary flow channel core segment 205 has a flow channel extending from the tooth-yoke junction to the third position on each stator tooth, and a flow channel opening is provided at the tooth tip of each stator tooth;

[0127] The connecting core segment 206 has a connecting hole at a third position on each stator tooth, and a flow channel opening at the tip of each stator tooth;

[0128] The three-stage flow channel core segment 207 has a flow channel extending from the third position to the tooth tip on each stator tooth;

[0129] The tooth tip flow channel iron section 208 has a flow channel at the tooth tip of each stator tooth;

[0130] Among them, in each stator tooth, the third position is located between the tooth yoke junction and the tooth tip.

[0131] The sub-flow channel segment structure assembled based on the above eight core segments is as follows: Figure 19 shown.

[0132] Similarly, in order to make the inner walls of the flow channels in each core segment in the first-level flow channel fit tightly, in this embodiment, the radially outermost end is the head end, and the radially innermost end is the tail end. The tail end of the flow channel mouth core segment is a circular arc, the head and tail ends of the drainage hole set on the yoke in the first-level drainage core segment are both circular arcs, and the head and tail ends of the drainage hole at the junction of the tooth yoke in the second-level drainage core segment are both circular arcs; the tail end arc of the drainage hole in the flow channel mouth core segment coincides with the center of the head end arc of the drainage hole in the first-level drainage core segment and the apertures are equal; the tail end arc of the drainage hole in the first-level drainage core segment coincides with the center of the head end arc of the drainage hole in the second-level drainage core segment and the apertures are equal.

[0133] Example 3:

[0134] A stator core with a fractal multi-stage flow channel on the teeth. In this embodiment, a total of two levels of flow channels are provided, and the cooling medium flow path inside the stator core is as follows: Figure 20 As shown, the cooling medium flows in from multiple inlets, flows along the inlets to the primary stepped flow channel and the secondary micro-flow channel, flows radially inward at the stator core tooth yoke, and flows axially to the nearest outlets on both sides. If the nearest outlet is located in the middle of the motor, the cooling medium flows through the outlet to the secondary micro-flow channel and the primary stepped flow channel, and flows radially outward from the outer surface of the stator core; if the nearest outlet is located at both ends of the motor, the cooling medium flows out through the tooth tip flow channel outlet.

[0135] In each flow channel segment, the sub-flow channel segment structure on one side is as follows Figure 21 As shown. Based on the same considerations as in Examples 1 and 2, this embodiment follows the principle of minimizing the blocking of the motor magnetic circuit by designing the microchannel, positioning the microchannel close to the heat source, and increasing the heat dissipation area. Six different stator tooth yoke silicon steel sheets are designed for the stator core axial radial fractal microchannel heat sink according to its axial spatial layout. After stacking, six stator core segments are correspondingly formed. The six stator core segments are arranged and stacked in a specific combination to form a single-sided sub-channel segment. Two sub-channel segments are arranged in a mirror-symmetrical manner to form a complete channel segment. Multiple channel segments are arranged in sequence along the axial direction to form the entire stator core.

[0136] Specifically, the sub-flow channel segment includes: a flow channel opening core segment 301, a first-stage diversion core segment 302, a second-stage diversion core segment 303, a yoke flow channel opening core segment 304, a second-stage flow channel core segment 305, and a tooth tip flow channel opening core segment 306.

[0137] The runner opening core segment 301 has a runner opening provided at the intersection of its outer circumference and the extension line of the center of each stator tooth;

[0138] The first-stage drainage core segment 302 has a yoke portion provided with drainage holes corresponding to the stator teeth; each drainage hole in the first-stage drainage core segment 302 partially overlaps with the corresponding flow channel opening in the flow channel opening core segment 301;

[0139] The second-stage drainage core segment 303 has drainage holes at the junction of the tooth yokes of each stator tooth; each drainage hole in the second-stage drainage core segment 303 partially overlaps with the corresponding drainage hole in the first-stage drainage core segment 302;

[0140] The yoke core segment 304 has a flow opening at the junction of each stator tooth and the yoke. Each flow opening in the yoke core segment 304 partially overlaps with the corresponding drainage hole in the second-stage drainage core segment 303.

[0141] The secondary flow channel core segment 305 has a flow channel extending from the tooth-yoke junction to the tooth portion on each stator tooth;

[0142] The tooth tip flow channel opening core segment 306 has a flow channel opening at the tooth tip of each stator tooth.

[0143] The sub-flow channel segment structure assembled based on the above six core segments is as follows: Figure 22 shown.

[0144] Similarly, in order to make the inner walls of the flow channels in each core segment in the first-level flow channel fit tightly, in this embodiment, the radially outermost end is the head end, and the radially innermost end is the tail end. The tail end of the flow channel mouth core segment is a circular arc, the head and tail ends of the drainage hole set on the yoke in the first-level drainage core segment are both circular arcs, and the head and tail ends of the drainage hole at the junction of the tooth yoke in the second-level drainage core segment are both circular arcs; the tail end arc of the drainage hole in the flow channel mouth core segment coincides with the center of the head end arc of the drainage hole in the first-level drainage core segment and the apertures are equal; the tail end arc of the drainage hole in the first-level drainage core segment coincides with the center of the head end arc of the drainage hole in the second-level drainage core segment and the apertures are equal.

[0145] Example 4:

[0146] A permanent magnet motor comprises a stator core provided by any one of embodiments 1 to 3, the stator core having a fractal multi-stage flow channel on its teeth.

[0147] The active components of a high-power-density permanent magnet aircraft generator primarily consist of a stator core, windings, a rotor core, and magnets. Because high-speed rotor rotation causes significant frictional losses, this embodiment utilizes a novel cooling design exclusively for the stator assembly. In this embodiment's stator assembly design, the motor housing fits tightly against the outer surface of the stator core. An oil separator is positioned in the air gap, closely contacting the stator teeth. Seals are formed between the ends of the stator separator and the front and rear end covers of the motor to prevent cooling medium from leaking into the rotor assembly. In other words, the stator side of the aircraft generator designed using this embodiment forms a closed structure, completely enclosing the stator core and windings through the housing, front and rear end covers, and stator separator. In this embodiment, an oil inlet is provided in the axial middle portion of the casing, and a groove on the outer edge of the stator inlet core segment forms an annular cooling medium inlet channel between the casing and the stator core. After the cooling medium enters the motor casing through the oil inlet, it flows circumferentially along the groove on the outer edge of the stator inlet core segment and evenly enters the drainage holes corresponding to each stator tooth. The cooling medium flows radially along the axis of the microchannel structure inside the stator core toward the two ends of the core, cooling the stator core and the windings in the slots, and flows out through the tooth tip flow channel outlets at both ends of the stator core to cool the winding ends.

[0148] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A stator core having a fractal multi-stage flow channel on its teeth, characterized in that: It includes a plurality of flow channel sections distributed in sequence along the axial direction; In the flow channel section, a flow channel opening is provided at the intersection of the center extension line of each stator tooth and the outer circumference of the median section, and the flow channel section includes two sub-flow channel sections that are mirror-symmetrical about the median section; the median section is the section located in the middle of the axial direction; In the sub-flow channel section, N levels of flow channels are provided in the radial direction of each stator tooth, distributed sequentially from the yoke to the tooth. One first-level flow channel is provided, one end of which is connected to the corresponding flow channel opening and the other end is located at the intersection of the tooth and yoke. One second-level flow channel is provided, which is connected to the first-level flow channel at the intersection of the tooth and yoke. From the second to the Nth level flow channels, the number of flow channels in each level is twice the number of flow channels in the previous level, and in two adjacent levels of flow channels, the previous level flow channel is connected to two of the next level flow channels. The final flow passages in two adjacent sub-flow passage sections belonging to the same flow passage section are not directly connected, and the final flow passages in two adjacent sub-flow passage sections belonging to different flow passage sections are connected via an axial flow passage at the tooth tip; Wherein, N is a positive integer greater than or equal to 2.

2. The stator core having a fractal multi-stage flow channel on the teeth according to claim 1, wherein: Among the second to Nth level flow channels, the width of the previous level flow channel in two adjacent levels of flow channels is twice the width of the next level flow channel.

3. The stator core having a fractal multi-stage flow channel on the teeth according to claim 2, wherein: Among the flow channel sections, the last-stage flow channel is the longest and is evenly distributed in the axial direction.

4. The stator core having a fractal multi-stage flow channel on a tooth portion according to any one of claims 1 to 3, wherein: The first-stage flow channel is a stepped flow channel.

5. The stator core having a fractal multi-stage flow channel on the teeth according to claim 4, wherein: The first-stage flow channel is a three-stage stepped flow channel.

6. The stator core having a fractal multi-stage flow channel on the teeth according to claim 4, wherein: The value of N is 2, 3 or 4.

7. The stator core having a fractal multi-stage flow channel on the teeth according to claim 6, wherein: N＝4； Furthermore, the sub-flow channel segments include, in order along the axial direction: a flow channel mouth iron core segment, a first-level four-level flow channel iron core segment, a first-level three-level flow channel iron core segment, a yoke flow channel mouth three-level flow channel iron core segment, a second-level three-level flow channel iron core segment, a second-level four-level flow channel iron core segment, a second-level three-level flow channel iron core segment, a third-level flow channel iron core segment, a fourth-level flow channel iron core segment, and a tooth tip flow channel mouth iron core segment; The runner opening core segment is provided with a runner opening at the intersection of the outer circumference thereof and the extension line of the center of each stator tooth; The first-level and fourth-level flow channel core segments have a yoke portion provided with a drainage hole corresponding to each stator tooth, and each tooth portion is provided with a flow channel extending from the second position to the tooth tip; each drainage hole in the first-level and fourth-level flow channel core segments partially overlaps with the corresponding flow channel opening in the flow channel opening core segment; The first-level and third-level flow channel core segments are provided with drainage holes at the junction of the tooth yokes of each stator tooth, each stator tooth is provided with a flow channel extending from the first position to the second position, and the tooth tip of each stator tooth is provided with a flow channel opening; each drainage hole in the first-level and third-level flow channel core segments partially overlaps with the corresponding drainage hole in the first-level and fourth-level flow channel core segments; The three-stage runner core section of the yoke runner opening has runner openings at the tooth yoke junction and tooth tip of each stator tooth, and a runner extending from a first position to a second position is provided on each stator tooth; The secondary and tertiary flow channel core segments are provided with a flow channel extending from the tooth yoke junction to the second position on each stator tooth, and a flow channel opening is provided on the tooth tip of each stator tooth; The two-stage four-stage flow channel core segment has a flow channel on each stator tooth extending from the tooth yoke junction to the first position, and a flow channel extending from the second position to the tooth tip; The secondary flow channel core segment has a flow channel extending from the tooth yoke junction to the first position on each stator tooth, and a flow channel opening is provided at the tooth tip of each stator tooth; The three-stage flow channel core segment has a flow channel extending from a first position to a second position on each stator tooth, and a flow channel opening is provided at the tooth tip of each stator tooth; The four-stage flow channel core segment has a flow channel extending from the second position to the tooth tip on each stator tooth; The tooth tip flow channel opening core section has a flow channel opening at the tooth tip of each stator tooth; Among them, in each stator tooth, the tooth yoke junction, the first position, the second position, and the tooth tip are arranged in sequence.

8. The stator core having a fractal multi-stage flow channel on the teeth according to claim 6, wherein: N＝3； Furthermore, the sub-flow channel segment includes: a flow channel opening core segment, a first-stage drainage core segment, a second-stage drainage core segment, a yoke flow channel opening core segment, a second-stage flow channel core segment, a connecting core segment, a third-stage flow channel core segment, and a tooth tip flow channel opening core segment, which are sequentially arranged along the axial direction. The runner opening core segment is provided with a runner opening at the intersection of the outer circumference thereof and the extension line of the center of each stator tooth; The first-stage diversion core segment has a yoke portion provided with diversion holes corresponding to the stator teeth; each diversion hole in the first-stage diversion core segment overlaps with the corresponding flow channel opening portion in the flow channel opening core segment; The second-stage drainage core segment has drainage holes at the junction of the tooth yoke of each stator tooth; and the tooth portion is provided with a flow channel extending from the third position to the tooth tip; each drainage hole in the second-stage drainage core segment partially overlaps with the corresponding drainage hole in the first-stage drainage core segment; The yoke core section has runner openings, where the tooth-yoke junction and tooth tip of each stator tooth are provided with runner openings, and a connecting hole is provided at the third position of each stator tooth; The secondary flow channel core segment has a flow channel extending from the tooth yoke junction to the third position on each stator tooth, and a flow channel opening is provided at the tooth tip of each stator tooth; The connecting core segment has a connecting hole at a third position on each stator tooth, and a flow channel opening at the tooth tip of each stator tooth; The three-stage flow channel core segment has a flow channel extending from the third position to the tooth tip on each stator tooth; The tooth tip flow channel opening core section has a flow channel opening at the tooth tip of each stator tooth; Among them, in each stator tooth, the third position is located between the tooth yoke junction and the tooth tip.

9. The stator core having a fractal multi-stage flow channel on the teeth according to claim 6, wherein: N＝2； Furthermore, the sub-flow channel segment includes: a flow channel opening core segment, a first-stage drainage core segment, a second-stage drainage core segment, a yoke flow channel opening core segment, a second-stage flow channel core segment, and a tooth tip flow channel opening core segment, which are sequentially arranged along the axial direction. The runner opening core segment is provided with a runner opening at the intersection of the outer circumference thereof and the extension line of the center of each stator tooth; The first-stage diversion core segment has a yoke portion provided with diversion holes corresponding to the stator teeth; each diversion hole in the first-stage diversion core segment overlaps with the corresponding flow channel opening portion in the flow channel opening core segment; The second-stage drainage core segment has drainage holes at the junction of the tooth yokes of each stator tooth; each drainage hole in the second-stage drainage core segment partially overlaps with the corresponding drainage hole in the first-stage drainage core segment; The yoke runner core section has a runner opening at the junction of each stator tooth and the yoke; each runner opening in the yoke runner core section partially overlaps with the corresponding drainage hole in the second-stage drainage core section; The secondary flow channel core segment has a flow channel on each stator tooth extending from the tooth yoke junction to the tooth portion; The tooth tip flow channel opening iron core section has a flow channel opening at the tooth tip of each stator tooth.

10. A permanent magnet motor, characterized in that: A stator core comprising the stator core having a fractal multi-stage flow channel on the teeth as claimed in any one of claims 1 to 9.

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