Back winding type flat wire hairpin permanent magnet high-speed motor stator

Abstract

The invention discloses a back-wound flat wire hairpin permanent magnet high-speed motor stator, which is suitable for a high-speed magnetic suspension motor and a new energy automobile driving motor, and solves the problems of low assembly efficiency and unreliable connection of a multi-layer winding of an existing back-wound stator. The stator core is provided with a radial inner groove and a radial outer groove, the inner groove is deeper than the outer groove, and the bottom of the inner groove is provided with an axial ventilation channel; the welding ends at the tail ends of the outer leg and the inner leg are coplanar and twisted, and automatic welding is adapted; the confluence assembly comprises no less than four special-shaped copper bars matched with radial differences of welding ends, double neutral conducting rings for collecting neutral points in a layered manner, six short-circuit conducting pieces for unifying potential connection with the outside, and an injection molding insulating layer wrapping an interlayer connection unit. The stator realizes automatic assembly and reliable connection of multiple layers of windings, gives consideration to heat dissipation, compactness and stability, and improves motor energy efficiency and assembly qualified rate.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a back-wound flat wire hairpin permanent magnet high-speed motor stator. Background Technology

[0002] Stator designs are suitable for applications requiring high structural compactness and production automation, such as high-speed magnetic levitation motors and drive motors for new energy vehicles. In these applications, back-wound stators have become the mainstream structural choice for high-speed motors because they can effectively shorten the winding end length and reduce the overall size of the motor.

[0003] However, when adapting existing back-wound stator solutions to multi-layer windings, if a full stator round wire dispersed winding structure is adopted, the windings need to be installed manually by threading the wires. This not only results in low assembly efficiency but also easily damages the winding insulation layer during the threading process, leading to insufficient reliability of subsequent connections. If a modular stator structure is adopted, although independent winding of each module can be achieved, the interlayer welding of the multi-layer windings needs to be completed manually after the modules are spliced. This not only increases the assembly process but also makes it difficult to adapt to the automated production line of the full stator. At the same time, existing interlayer connection components cannot adapt to the positional differences of the welding ends of the multi-layer windings. Either a large amount of clearance is required, which increases the size of the motor, or the interlayer conductivity reliability is affected by connection misalignment. Summary of the Invention

[0004] The main objective of this invention is to provide a back-wound flat wire hairpin permanent magnet high-speed motor stator. The aim is to achieve automated assembly of the multi-layer windings of the stator by designing a structure in which "the welding ends of the multi-layer hairpin windings are coplanar and the inter-layer connection units are adapted to the differences in the welding end positions", while ensuring the reliability of the inter-layer connections and taking into account both the motor production efficiency and operational stability.

[0005] To achieve the above objectives, this invention proposes a back-wound flat wire hairpin permanent magnet high-speed motor stator, comprising: The stator core has slots distributed along the circumference for mounting windings. A multi-layer hairpin winding is embedded in the slot. Each hairpin winding has two conductive segments. The free ends of the conductive segments form welding ends. All welding ends are located in the same axial section, which can be adapted to automated welding. The busbar assembly includes an interlayer connection unit that can adapt to the positional differences of the welding ends of adjacent layers, electrically connecting the welding ends of the hairpin windings of adjacent layers to form a current path that connects the beginning and end, thereby realizing reliable interlayer connection of multi-layer hairpin windings and automated assembly of the stator.

[0006] The stator core slots provide an installation base for the multi-layer hairpin windings. Combined with the design that "the welding ends of the multi-layer hairpin windings are located in the same axial section", it can be directly adapted to automated welding equipment, avoiding the precision deviation of manual welding. At the same time, the inter-layer connection unit in the busbar assembly can adapt to the positional differences of the welding ends of adjacent layers, and can achieve reliable electrical connection without manual adjustment. Ultimately, it not only solves the problem of low automated assembly efficiency of the entire stator multi-layer windings, but also ensures the reliability of inter-layer connections, balancing production efficiency and motor operation stability.

[0007] In one possible implementation, the groove includes an inner groove and an outer groove distributed radially along the stator core, the depth of the inner groove being greater than the depth of the outer groove, and the bottom of the inner groove forming a ventilation channel extending axially.

[0008] By using differentiated slots with an inner slot depth greater than the outer slot, the installation requirements of multi-layer windings distributed radially can be precisely matched, avoiding insulation damage caused by the compression of windings in the slot. The axial ventilation channel at the bottom of the inner slot can directly form a heat dissipation path, accelerating the heat dissipation during winding operation. This not only improves the utilization rate of stator radial space but also solves the problem of insufficient heat dissipation of multi-layer windings, ensuring long-term high-load operation of the motor.

[0009] In one possible implementation, the hairpin winding is a U-shaped structure, with two conductive segments of the U-shaped structure being an outer leg and an inner leg, the outer leg being embedded in the outer groove, the inner leg being embedded in the inner groove, and the welding ends being formed at the ends of the outer leg and the inner leg away from the U-shaped bending segment.

[0010] With the above solution, the outer and inner legs of the U-shaped hairpin winding are respectively embedded in the outer and inner slots. Its U-shaped bending section can naturally achieve winding connection across the slots without the need for additional wire transition, effectively shortening the winding end length. At the same time, the welding ends are formed at the ends of the outer and inner legs respectively, which can accurately dock with the interlayer connection unit. This not only solves the problem of poor compatibility between traditional windings and layered slots, but also further reduces the axial dimension of the motor, meeting the requirements of compact design.

[0011] In one possible implementation, the interlayer connection unit includes at least one irregularly shaped conductive element having a transition section adapted to the radial distance between adjacent layer welding ends, and a connection interface that can match the welding ends.

[0012] Through the above technical solution, the transition section of the irregular conductive component can be flexibly adapted according to the radial distance of the welding ends of adjacent layers, avoiding the problem that existing straight connectors cannot be connected due to positional differences; the connection interface can match the shape of the welding end, realizing a precise connection of "one-time installation", without the need for repeated manual calibration, which simplifies the interlayer connection process and improves the connection reliability, providing key support for automated assembly.

[0013] In one possible implementation, the irregularly shaped conductive component is an irregularly shaped copper busbar, the connection interface is adapted to the welding end, and the number of irregularly shaped copper busbars is not less than four, each corresponding to the welding end of a four-layer hairpin winding.

[0014] Through the above solution, the irregular copper busbar has high conductivity, which can reduce the resistance loss of interlayer connection and improve the energy efficiency of motor; the U-shaped groove interface can wrap the edge of the welding end, ensuring accurate positioning during welding and reducing the risk of poor welding.

[0015] In one possible implementation, the bus assembly further includes a neutral point converging unit, which can collect the three-phase neutral points of the multi-layer hairpin winding and achieve potential unification of each neutral point.

[0016] Through the above scheme, the neutral point gathering unit can centrally collect the three-phase neutral points of the multi-layer hairpin winding, avoiding the problems of wire crossing and insulation failure caused by traditional decentralized connection; at the same time, through the unified potential design, it can eliminate the potential deviation of the neutral points of each phase, prevent the three-phase current imbalance, solve the problem of unstable operation caused by the lack of neutral point treatment in multi-layer winding, and improve the stability of motor output torque.

[0017] In one possible implementation, the neutral point gathering unit includes an inner neutral conductive ring and an outer neutral conductive ring arranged coaxially. The inner neutral conductive ring is used to collect the neutral points of the inner windings near the center of the stator core, and the outer neutral conductive ring is used to collect the neutral points of the outer windings near the outer periphery of the stator core.

[0018] Through the above technical solution, the inner and outer neutral conductive rings correspond to the radial positions of the inner and outer windings, respectively, and can collect neutral points in a targeted manner, avoiding interference caused by the mixing of neutral points at different radial positions; the coaxial structure can ensure the circumferential alignment of the three-phase interface, further improving the neutral point collection accuracy, which not only solves the problem that single-ring convergence cannot adapt to the radial differences of multi-layer windings, but also provides a stable foundation for subsequent potential unification.

[0019] In one possible implementation, the neutral point converging unit further includes six short-circuit conductive elements. Three of the short-circuit conductive elements are connected to the inner neutral conductive ring and the outer neutral conductive ring, respectively. One end of each short-circuit conductive element is fixedly connected to the corresponding neutral conductive ring, and the other end extends to the outside of the stator. This can unify the potential of the inner and outer neutral conductive rings to a common neutral point and achieve direct connection with external circuits.

[0020] With the above scheme, three of the six short-circuiting conductive parts are connected to the inner and three to the outer neutral conductive rings, which makes the current distribution between the two rings more uniform and avoids current concentration and local heating caused by single-point connection. The other end of the short-circuiting conductive parts extends to the outside and can be directly connected to the external circuit without the need for additional adapter structure, simplifying the neutral point connection process between the stator and the external system. At the same time, the three symmetrically distributed connection points of each of the two rings can further ensure the stability of the potential uniformity, minimize the potential difference between the inner and outer neutral conductive rings, reduce circulating current loss, and improve the convenience and reliability of the motor connection to the external circuit.

[0021] In one possible implementation, the multi-layer hairpin winding has at least two layers, which are radially distributed along the stator core, and the welded ends of adjacent winding layers do not interfere radially.

[0022] Through the above technical solutions, the design of at least two winding layers can meet the current carrying requirements of motors with different power levels and adapt to diverse application scenarios; the layout requirement of "no radial interference at the welding ends of adjacent layers" can avoid structural damage caused by collisions between interlayer components during assembly, ensure smooth winding embedding and connection process, improve the qualification rate of stator assembly, and reduce production losses.

[0023] In one possible implementation, the welding end of the hairpin winding is twisted, and the twisting direction is adapted to the connection interface position of the interlayer connection unit; the bus assembly further includes an injection-molded insulating layer that wraps around the interlayer connection unit.

[0024] Through the above technical solutions, the twisting treatment at the welding end can accurately adapt to the interface position of the interlayer connection unit, reducing welding deviation; the injection-molded insulation layer outside the busbar assembly can fully wrap the interlayer connection unit, isolating external interference such as moisture and dust, which not only improves welding reliability, but also enhances the insulation performance of the busbar assembly and reduces the risk of motor short circuit failure. Attached Figure Description

[0025] 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 the structures shown in these drawings without creative effort.

[0026] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is an exploded structural diagram of the present invention; Figure 3 This is a structural diagram of the hairpin winding of the present invention; Figure 4This is an exploded view of the hairpin winding of the present invention; Figure 5 This is a structural diagram of the busbar assembly and winding of the present invention; Figure 6 This is a diagram showing the connection between the irregularly shaped copper busbar and the hairpin winding of the present invention; Figure 7 This is a perspective view of the busbar assembly of the present invention; Figure 8 This is an exploded view of the busbar assembly of the present invention; Explanation of icon numbers: 1. Stator core; 10. Outer slot; 11. Inner slot; 2. Ventilation channel; 3. Hairpin winding; 31. Welding end; 32. Inner leg; 33. Outer leg; 34. First layer hairpin; 35. Second layer hairpin; 36. Third layer hairpin; 37. Fourth layer hairpin; 4. Busbar assembly; 41. Irregularly shaped conductive component; 43. Inner neutral conductive ring; 44. Outer neutral conductive ring; 45. Short-circuit conductive component.

[0027] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0029] like Figure 1-8 As shown, the present invention proposes a back-wound flat wire hairpin permanent magnet high-speed motor stator. The stator core 1 has several sets of slots evenly distributed along the circumferential direction. Each set of slots includes an inner slot 11 and an outer slot 10 distributed radially. The depth of the inner slot 11 is greater than the depth of the outer slot 10, and the bottom of the inner slot 11 is provided with a ventilation channel 2 extending axially.

[0030] like Figure 2 As shown, this structural design provides space for the layered installation of the multi-layer hairpin winding 3, allowing windings of different layers to be respectively installed in the inner slot 11 and the outer slot 10, avoiding damage to the insulation layer caused by the windings squeezing each other in the slots. On the other hand, the ventilation channel 2 at the bottom of the inner slot 11 can form a dedicated heat dissipation path, accelerating the heat dissipation generated during winding operation. This not only improves the radial space utilization of the stator but also solves the problem of insufficient heat dissipation of multi-layer windings, ensuring that the motor can operate under high load for a long time.

[0031] like Figure 2-4As shown, the multi-layer hairpin winding 3 is embedded in the slot of the stator core 1, adopting a U-shaped structure. The two conductive sections of each hairpin winding 3 are the outer leg 33 and the inner leg 32. The outer leg 33 is embedded in the outer slot 10 of the stator core 1, and the inner leg 32 is embedded in the inner slot 11 of the stator core 1. The welding ends 31 are formed at the ends of the outer leg 33 and the inner leg 32 away from the U-shaped bending section. All welding ends 31 are located in the same axial section of the stator core 1, and the welding ends 31 are twisted, with the twisting direction matching the connection interface position of the interlayer connection unit in the subsequent busbar assembly 4.

[0032] The U-shaped structure design allows for cross-slot connections of the windings without the need for additional wires, effectively shortening the winding end length and reducing the axial dimension of the motor, meeting the requirements of compact design. The coplanar and twisted welding ends 31 can be directly adapted to automated welding equipment, avoiding the precision deviations of manual welding, and ensuring precise docking with interlayer connection units, providing a foundation for automated assembly. Meanwhile, the multi-layer hairpin winding 3 has at least two layers, radially distributed along the stator core 1, with no radial interference at the welding ends 31 of adjacent winding layers. This layout not only meets the current carrying requirements of motors with different power ratings and adapts to diverse application scenarios, but also avoids structural damage caused by collisions between interlayer components during assembly, ensuring smooth winding insertion and connection, improving the stator assembly qualification rate, and reducing production losses.

[0033] like Figure 7-8 As shown, the busbar assembly 4 includes an interlayer connection unit, a neutral point converging unit, and an injection-molded insulating layer. The interlayer connection unit is the core for achieving reliable connection of the multi-layer hairpin windings 3, and includes at least one irregularly shaped conductive element 41. In this embodiment, the number is no less than four, each corresponding to the welding ends 31 of the four layers of hairpin windings 3. Each irregularly shaped conductive element 41 has a transition section and a connection interface. The transition section can adapt to the radial distance of the welding ends 31 of adjacent layers, and the connection interface is used to adapt to the welding ends 31. The high conductivity of the irregularly shaped copper busbar can reduce the resistance loss of the interlayer connection and improve the energy efficiency of the motor; the connection interface can wrap the edge of the welding end 31 to ensure accurate positioning during welding and reduce the risk of poor soldering; the transition section can flexibly adapt to the radial differences of the welding ends 31 of adjacent layers, avoiding the problem of existing straight connectors being unable to connect due to positional differences, simplifying the interlayer connection process and improving connection reliability.

[0034] Meanwhile, the neutral point gathering unit in the bus assembly 4 includes an inner neutral conductive ring 43, an outer neutral conductive ring 44, and six short-circuiting conductive elements 45 arranged coaxially. The inner neutral conductive ring 43 is close to the center side of the stator core 1 and is used to collect the neutral point of the inner winding near the center of the stator core 1. The outer neutral conductive ring 44 is close to the outer periphery side of the stator core 1 and is used to collect the neutral point of the outer winding near the outer periphery of the stator core 1.

[0035] Three shorting conductive elements 45 are respectively connected to the inner neutral conductive ring 43 and the outer neutral conductive ring 44. One end of the shorting conductive element 45 is fixedly connected to the corresponding neutral conductive ring, and the other end extends to the outside of the stator.

[0036] The coaxial arrangement of the dual neutral conductive rings ensures circumferential alignment of the three-phase interfaces, with neutral points collected specifically at the radial positions of the inner and outer windings respectively. This avoids interference caused by mixing neutral points at different radial positions and solves the problem that single-ring convergence cannot adapt to the radial differences of multi-layer windings. The design of six short-circuit conductive elements 45 allows the inner and outer neutral conductive rings 44 to be connected by three short-circuit conductive elements 45, resulting in a more uniform current distribution between the two rings. This avoids current concentration and localized heating caused by single-point connections. At the same time, the short-circuit conductive elements 45 extend to the outside of the stator, allowing direct connection to external circuits without additional adapter structures. This simplifies the neutral point connection process between the stator and external systems and unifies the potential of the inner neutral conductive ring 43 and the outer neutral conductive ring 44 to a common neutral point, minimizing the potential difference between the two rings, reducing circulating current losses, and improving the convenience and reliability of connecting the motor to external circuits.

[0037] In addition, the busbar assembly 4 also includes an injection-molded insulation layer, which wraps the interlayer connection unit and can isolate external interference such as moisture and dust, thereby improving welding reliability and enhancing the insulation performance of the busbar assembly 4, reducing the risk of motor short-circuit faults.

[0038] like Figure 6 As shown, specifically in this embodiment, the hairpin winding 3 consists of a first layer of hairpins 34, a second layer of hairpins 35, a third layer of hairpins 36, and a fourth layer of hairpins 37, arranged sequentially from the bottom of the slot to the outside. The specific connection relationship is as follows: the outer leg 33 of the first layer of hairpins 34 is connected to the inner leg 32 of the fourth layer of hairpins 37 of the adjacent hairpin winding 3 via a shaped copper busbar; the outer leg 33 of the second layer of hairpins 35 is connected to the inner leg 32 of the first layer of hairpins 34 via a shaped copper busbar; the outer slot 10 of the third layer of hairpins 36 is connected to the inner leg 32 of the first layer of hairpins 34 via a shaped copper busbar; and the outer leg 33 of the fourth layer of hairpins 37 is connected to the inner leg 32 of the third layer of hairpins 36 via a shaped copper busbar.

[0039] Through the above connections, the four hairpin windings 3 form an interconnected current network: the inner leg 32 of the fourth hairpin 37 receives current from the outer leg 33 of the first layer, conducts it through its own winding to the outer leg 33, and then transmits it to the third layer through the copper busbar connecting the outer leg 33 of the fourth layer and the inner leg 32 of the third layer; the current of the third hairpin 36 flows into the first layer through the outer leg 33 and the copper busbar connecting the outer leg 33 of the third layer and the inner leg 32 of the first layer; at the same time, the current of the second hairpin 35 flows into the inner leg 32 of the first layer through the outer leg 33 and the corresponding copper busbar, making the first layer a current convergence node; the current converged in the first layer then flows back to the fourth layer through the outer leg 33 and the copper busbar connecting the outer leg 33 of the first layer and the inner leg 32 of the fourth layer, forming a complete current cycle, ensuring that the current distribution of each layer winding is balanced and there is no local overload.

[0040] The neutral point converging unit is configured in coordination with the aforementioned connection structure. The inner neutral conductive ring 43 is located near the stator center and collects the neutral point current of the inner windings, namely the first and second hairpins. Its three protruding connecting parts are welded to the irregularly shaped copper busbar connecting the second outer leg 33 and the first inner leg 32 through branch interfaces. This copper busbar can conduct the neutral point current of the second and first hairpins to the inner neutral conductive ring 43. The outer neutral conductive ring 44 is located near the stator periphery and collects the neutral point current of the outer windings, namely the third and fourth hairpins. Its three protruding connecting parts are welded to the irregularly shaped copper busbar connecting the fourth outer leg 33 and the third inner leg 32 through branch interfaces. This copper busbar can conduct the neutral point current of the fourth and third hairpins to the outer neutral conductive ring 44. Of the six short-circuit conductive parts 45, three are welded at one end to the protruding connection of the inner neutral conductive ring 43, and the other three are welded at one end to the protruding connection of the outer neutral conductive ring 44. The other ends extend axially to the outside of the stator, which not only unifies the potential of the inner and outer neutral conductive rings 44 to a common neutral point, but also directly connects to the neutral line of the external circuit, avoiding poor contact caused by additional transfer.

[0041] The injection-molded insulation layer of the busbar assembly 4 is made of heat-resistant insulating material, completely encasing all non-connected parts of the irregularly shaped copper busbars, the inner neutral conductive ring 43 and the outer neutral conductive ring 44, as well as the non-extension section of the short-circuit conductive component 45, with only the external mating end of the short-circuit conductive component 45 exposed. This design achieves insulation isolation of each connection part, preventing interlayer short circuits, and also fixes the position of the copper busbars and conductive rings, preventing the connection from loosening due to vibration during motor operation. At the same time, it isolates moisture and dust, improving connection reliability.

[0042] When the motor is working, the external power supply current is connected to the welding end 31 of a certain hairpin and then circulates along the connection path described above: for example, the current flows in from the outer leg 33 of the third hairpin 36, enters the first layer through the copper busbar connecting the outer leg 33 of the third layer and the inner leg 32 of the first layer, then passes through the outer leg 33 of the first layer and is transmitted to the inner leg 32 of the fourth layer through the corresponding copper busbar, and then flows back to the third layer through the fourth layer and the copper busbar connecting the fourth layer and the third layer, forming a complete circuit; at the same time, the inner and outer neutral conductive rings 44 collect the neutral point current of each layer through the corresponding copper busbar branches, and after being converged by the short-circuiting conductive part 45, they are connected to the external circuit to complete the neutral point circuit. The ventilation channel 2 at the bottom of the inner slot 11 continuously dissipates the heat generated by the winding operation, and with the protective effect of the injection-molded insulation layer, the motor can finally achieve efficient and stable operation.

[0043] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application and 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, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0044] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A back-wound flat wire hairpin permanent magnet high-speed motor stator, characterized in that, include: Stator core (1), wherein the stator core (1) is provided with slots distributed along the circumference, the slots being used to mount windings; Multi-layer hairpin winding (3), the multi-layer hairpin winding (3) is embedded in the slot, each hairpin winding (3) has two conductive segments, the free end of the conductive segment forms a welding end (31), all the welding ends (31) are located in the same axial section, which can be adapted to automated welding; The busbar assembly (4) includes an interlayer connection unit that can adapt to the positional differences of the welding ends (31) of adjacent layers, electrically connect the welding ends (31) of the hairpin windings (3) of adjacent layers, form a current path with the beginning and end connected, and realize reliable interlayer connection of the multi-layer hairpin windings (3) and automated assembly of the stator.

2. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 1, characterized in that, The groove includes an inner groove (11) and an outer groove (10) radially distributed along the stator core (1). The depth of the inner groove (11) is greater than the depth of the outer groove (10). The bottom of the inner groove (11) forms a ventilation channel (2) extending axially.

3. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 2, characterized in that, The hairpin winding (3) has a U-shaped structure. The two conductive segments of the U-shaped structure are the outer leg (33) and the inner leg (32). The outer leg (33) is embedded in the outer groove (10), and the inner leg (32) is embedded in the inner groove (11). The welding end (31) is formed at the end of the outer leg (33) and the inner leg (32) away from the U-shaped bending segment.

4. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 1, characterized in that, The interlayer connection unit includes at least one irregularly shaped conductive element (41), which has a transition section adapted to the radial distance of the adjacent layer welding end (31) and a connection interface that can match the welding end (31).

5. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 4, characterized in that, The irregular conductive component (41) is an irregular copper busbar, the connection interface is adapted to the welding end (31), and the number of irregular copper busbars is not less than four, which respectively correspond to the welding ends (31) of the four layers of hairpin windings (3).

6. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 1, characterized in that, The busbar assembly (4) also includes a neutral point converging unit, which can collect the three-phase neutral points of the multi-layer hairpin winding (3) and achieve the potential unification of each neutral point.

7. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 6, characterized in that, The neutral point gathering unit includes an inner neutral conductive ring (43) and an outer neutral conductive ring (44) arranged coaxially. The inner neutral conductive ring (43) is used to collect the neutral points of the inner windings near the center of the stator core (1), and the outer neutral conductive ring (44) is used to collect the neutral points of the outer windings near the outer periphery of the stator core (1).

8. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 7, characterized in that, The neutral point convergence unit also includes six short-circuit conductive elements (45). Three of the short-circuit conductive elements (45) are connected to the inner neutral conductive ring (43) and the outer neutral conductive ring (44), respectively. One end of the short-circuit conductive element (45) is fixedly connected to the corresponding neutral conductive ring, and the other end extends to the outside of the stator. This can unify the potential of the inner neutral conductive ring (43) and the outer neutral conductive ring (44) to a common neutral point and realize direct connection with the external circuit.

9. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 1, characterized in that, The multi-layer hairpin winding (3) has at least two layers, which are radially distributed along the stator core (1), and the welding ends (31) of adjacent winding layers do not interfere radially.

10. The stator of a back-wound flat wire hairpin permanent magnet high-speed motor according to claim 1, characterized in that, The welding end (31) of the hairpin winding (3) is twisted, and the twisting direction is adapted to the connection interface position of the interlayer connection unit; the bus assembly (4) also includes an injection-molded insulating layer, which wraps the interlayer connection unit.

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