Outer rotor 3d flux permanent magnet synchronous motor

Abstract

The application provides an outer rotor 3D magnetic flux permanent magnet synchronous motor, which comprises a rotor assembly, a stator assembly and a rotating shaft, the rotor assembly comprises a radial permanent magnet group and an axial permanent magnet group, the stator assembly comprises a stator core and an armature winding, the axial end portions of the two sides of the stator core are connected with magnetic yokes, the end faces of the magnetic yokes are provided with magnetic boots, and the radial winding grooves are formed between the adjacent magnetic boots; the armature winding comprises a plurality of winding units, and the bending portions at the two ends of each winding unit are embedded in the radial winding grooves on the two sides of the magnetic boots. The motor provided in the embodiment creatively uses the magnetic boots at the end portions of the stator core to guide the back winding arrangement of the winding, generates an axial armature magnetic field, combines the radial magnetic circuit and the axial magnetic circuit at the two end portions to form a hybrid excitation 3D magnetic flux structure, and the radial magnetic flux and the axial magnetic flux at the two sides work together in parallel to do work outward, so that the torque density and the load capacity of the motor are significantly improved.

Description

Technical Field

[0001] This utility model relates to the field of permanent magnet synchronous motor technology, specifically to an external rotor 3D flux permanent magnet synchronous motor. Background Technology

[0002] With its core characteristics of high torque density, high efficiency, and low noise, permanent magnet synchronous motor has become a key component of various mechanical transmission equipment and has been widely used in industries, transportation, and high-end manufacturing in recent years.

[0003] Traditional permanent magnet synchronous motors often employ a single magnetic circuit structure, such as radial flux motors or axial flux motors. The magnetic circuit design of a radial flux motor focuses on the radial plane between the rotor and stator, with magnetic flux primarily transmitted along the motor's radial direction. This results in underutilization of the axial end space and axial leakage flux, limiting the improvement of torque density. An axial flux motor (or disc motor) has a thin disc shape, with its magnetic circuit design concentrated in the axial plane, and magnetic flux flowing along the motor's axis. However, this design tends to lead to a larger radial dimension.

[0004] With the increasing demand for lightweight and miniaturized motors, the torque density bottleneck of such single-path magnetic circuit structures is becoming increasingly prominent, making it difficult to meet the "small size, high torque" requirements of high-load scenarios. Some solutions use a single stator dual rotor or single rotor dual stator structure to improve torque, but in essence, they are still a combination of single axial magnetic circuit structures, which will correspondingly increase the axial dimension, making them unsuitable for scenarios with requirements for axial space.

[0005] Therefore, how to overcome the shortcomings of the existing technology mentioned above has become the subject of this utility model. Utility Model Content

[0006] The purpose of this invention is to provide an external rotor 3D flux permanent magnet synchronous motor that can make full use of the axial space at the end to form an axial magnetic field, and use the radial magnetic field and the axial magnetic field to achieve 3D flux coupling to improve torque density.

[0007] To achieve the above objectives, the present invention employs an external rotor 3D flux permanent magnet synchronous motor, comprising: The rotor assembly includes a rotor core, a radial permanent magnet assembly, two rotor end caps, and an axial permanent magnet assembly. The rotor core is cylindrical. The radial permanent magnet assembly is fixedly disposed on the inner wall of the rotor core. The rotor end caps are connected to the axial ends of the rotor core. The axial permanent magnet assembly is fixedly disposed on the surface of the rotor end caps facing the rotor core. A stator assembly is coaxially disposed within the rotor core. The stator assembly includes a stator core and an armature winding. Stator teeth are provided on the outer circumferential surface of the stator core, and axial winding slots are formed between adjacent stator teeth. Magnetic yokes are connected to the axial ends of both sides of the stator core. Magnetic shoes are provided on the end faces of the magnetic yokes, and radial winding slots are formed between adjacent magnetic shoes. The axial winding slots and the radial winding slots are positioned one-to-one. The armature winding includes multiple winding units, each of which is wound in a ring on a stator tooth and its corresponding magnetic boots at both ends. The main body of the winding unit is embedded in the axial winding slots on both sides of the stator tooth, and the bent portions at both ends of the winding unit are embedded in the radial winding slots on both sides of the magnetic boot. A rotating shaft is coaxially disposed within the stator assembly and fixedly connected to the stator core. The rotating shaft is connected to the rotor end cover via a bearing.

[0008] Furthermore, the radial permanent magnet group comprises multiple radial permanent magnets, which are evenly distributed around the circumference on the inner wall of the rotor core, with adjacent radial permanent magnets having opposite polarity directions; the axial permanent magnet group comprises multiple axial permanent magnets, which are evenly distributed around the circumference on the surface of the rotor end cover facing the rotor core, with adjacent axial permanent magnets having opposite polarity directions.

[0009] Furthermore, the radial permanent magnet group contains the same number of radial permanent magnets as the axial permanent magnet group contains, and the magnetic pole centerline of each radial permanent magnet and the magnetic pole centerline of one axial permanent magnet are in the same radial plane.

[0010] Furthermore, both the radial permanent magnets and the axial permanent magnets in the same radial plane face the stator assembly with the same polarity.

[0011] Furthermore, the end of the magnetic shoe away from the magnetic yoke protrudes outward to form an axial boss. The side of the axial boss forms a limit for the winding unit, and an axial air gap is formed between the end face of the axial boss and the axial permanent magnet assembly.

[0012] Furthermore, the stator tooth extends to both sides from the end away from the axis to form a radial boss. The side of the radial boss forms a limit for the winding unit, and a radial air gap is formed between the end face of the radial boss and the radial permanent magnet assembly.

[0013] Furthermore, the size ratio of the axial air gap to the radial air gap is 1 to 2.

[0014] Furthermore, a mounting groove is provided on the surface of the rotor end cover facing the rotor core, and the axial permanent magnet assembly is embedded in the mounting groove.

[0015] Furthermore, one of the two rotor end caps is integrally formed with the rotor core, while the other is detachably connected to the rotor core.

[0016] Furthermore, a limiting structure is provided at the detachable connection position between the rotor end cover and the rotor core, the limiting structure being used to restrict the position of the rotor end cover in the circumferential direction.

[0017] The technical solution provided in this application has the following technical effects: By setting a magnetic yoke and magnetic shoes at the ends of the stator core, and arranging the winding units around the magnetic shoes in a back-wound configuration, the winding units can simultaneously couple with both radial and axial permanent magnet groups, forming a 3D magnetic flux path. Compared to traditional single-direction magnetic field motors, the 3D magnetic flux path can perform work in parallel in both the axial and radial directions, achieving high torque density output. Furthermore, since the axial and radial magnetic fluxes share the same set of windings, and the magnetic yoke and magnetic shoes are also connected to the ends of the stator core, the axial end space of the motor is fully utilized, resulting in a compact and lightweight motor structure suitable for applications with limited axial space and high torque density requirements. Attached Figure Description

[0018] Appendix Figure 1 An exploded view of the motor as provided in an embodiment of this utility model; Appendix Figure 2 A cross-sectional view of the motor provided for an embodiment of this utility model; Appendix Figure 3 A schematic diagram of the stator assembly (including the rotating shaft) provided in an embodiment of this utility model. Appendix Figure 4 An axial view of a stator assembly provided in an embodiment of this utility model; Appendix Figure 5 A schematic diagram of the stator core provided in an embodiment of this utility model; Appendix Figure 6 A three-dimensional shape schematic diagram of a winding unit provided for an embodiment of this utility model; Appendix Figure 7 A schematic diagram of the rotor assembly provided in an embodiment of this utility model; Appendix Figure 8 This is a schematic diagram showing the magnetic pole directions of the radial permanent magnet and the axial permanent magnet on the same radial plane in an embodiment of this utility model.

[0019] In the above figures: 1. Rotor assembly; 11. Rotor core; 12. Radial permanent magnet assembly; 12a. Radial permanent magnet; 13. Rotor end cover; 13a. Mounting slot; 14. Axial permanent magnet assembly; 14a. Axial permanent magnet; 2. Stator assembly; 21. Stator core; 22. Armature winding; 23. Stator tooth; 23a. Radial boss; 24. Axial winding slot; 25. Magnetic yoke; 26. Magnetic shoe; 26a. Axial boss; 27. Radial winding slot; 31. Winding unit; 31a. Main body; 31b. Bending part; 4. Shaft; 41. Bearing; 51. Radial air gap; 52. Axial air gap. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0022] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0023] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0024] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0025] join Figure 1 , 3 7. This embodiment provides an external rotor 3D flux permanent magnet synchronous motor, such as... Figure 1 As shown, the motor mainly consists of three parts: rotor assembly 1, stator assembly 2, and shaft 4, all arranged coaxially. The stator assembly 2 is nested inside the rotor assembly 1, and the shaft 4 is fixedly connected to the stator assembly 2, forming a typical motor structure with an inner stator and an outer rotor.

[0026] like Figure 7 As shown, the rotor assembly 1 includes a rotor core 11, a radial permanent magnet assembly 12, a rotor end cap 13, and an axial permanent magnet assembly 14. The rotor core 11 is cylindrical in shape. The radial permanent magnet assembly 12 is fixedly disposed on the inner wall of the rotor core 11 to generate a radial permanent magnet field. The rotor end cap 13 is connected to both axial ends of the rotor core 11 to form a closed rotor cavity. The axial permanent magnet assembly 14 is mounted on the surface of the rotor end cap 13 facing the rotor core 11 to generate an axial permanent magnet field.

[0027] In this embodiment, the rotor core 11 is integrally formed with a rotor end cover 13, and the other rotor end cover 13 is detachably connected to the rotor core 11 by bolts or other means. This design simplifies the rotor assembly process and facilitates maintenance.

[0028] like Figure 3 As shown, the stator assembly 2 includes a stator core 21 and an armature winding 22. In this embodiment, the armature winding 22 adopts a concentrated winding, divided into 24 winding units 31. Each winding unit is connected to the others via end leads (simplified structure shown in the figure, not shown) according to a preset phase sequence and connection method to form a complete armature winding, which is then connected to an external three-phase power supply through terminals. Specifically, the upper edges of windings 1, 4, 7, 10, 13, 16, 19, and 22 are connected to phase U; the upper edges of windings 2, 5, 8, 11, 14, 17, 20, and 23 are connected to phase V; and the upper edges of windings 3, 6, 9, 12, 15, 18, 21, and 24 are connected to phase W. The three-phase windings can be connected in a star or delta configuration. In a star connection, the tail ends of the three phase windings are connected to a neutral point, and the three start ends are respectively used as the terminals of phase U, phase V, and phase W. In a delta connection, the start end of one phase winding is connected to the tail end of the adjacent phase winding in sequence to form a closed triangle, and the three connection points are respectively used as the terminals of phase U, phase V, and phase W.

[0029] The external three-phase power is connected to the corresponding U-phase, V-phase, and W-phase terminals of the armature winding, respectively. After being input into each phase winding, a rotating magnetic field is formed on the stator side. Since the phase windings are spatially 120° electrical degrees apart, the rotating magnetic field generated after the three-phase alternating current is applied rotates synchronously with the permanent magnet magnetic field of the rotor and always maintains a certain phase difference, thereby continuously generating electromagnetic torque to drive the rotor to rotate.

[0030] Figure 6 A simplified structure of a winding unit 31 is shown. To clearly illustrate the bending trajectory and overall shape of the winding, the pins used for connection of the winding unit 31 are omitted from the figure. Although Figure 6The winding unit 31 is simplified into a single unit, but in reality, each winding unit 31 consists of multiple coils. These coils are wound along the same trajectory and closely arranged to form an integral structure with a certain cross-sectional size to fit the spatial contour of the winding slot. The coils can be selected from round or flat wires depending on the motor's power requirements, space constraints, and heat dissipation requirements: When using round wires, multiple round wires are arranged in parallel, which can flexibly adapt to the complex shape of the slot, and the winding process is relatively simple; when using flat wires, a single flat wire has a larger conductor cross-sectional area, and multiple flat wires stacked or arranged in parallel can effectively fill the slot space, improving the slot fill factor. At the same time, the regular structure of the flat wire helps reduce the AC resistance and copper loss of the winding, enhances heat dissipation efficiency, and is more suitable for high power density scenarios. It is used to couple with a bidirectional magnetic field to generate electromagnetic torque.

[0031] like Figure 5 As shown, the stator core 21 has multiple stator teeth 23 arranged on its outer circumferential surface. These stator teeth 23 are evenly distributed around the circumference, and axial winding slots 24 are formed between adjacent stator teeth 23. Magnetic yokes 25 are also connected to the axial ends of both sides of the stator core 21. The magnetic yokes 25 have an annular structure, and multiple magnetic shoes 26 are arranged on the end face of the magnetic yokes 25. These magnetic shoes 26 are evenly distributed around the circumference on the end face of the magnetic yoke facing the rotor end cover.

[0032] The magnetic yoke 25 is mainly used to conduct the axial magnetic flux generated by the axial permanent magnet. The magnetic yoke 25 provides a low magnetic resistance path for the axial magnetic flux, preventing the axial magnetic flux from being directly lost. At the same time, the magnetic yoke 25 also serves as a structural support, connecting the multiple magnetic shoes 26 at the ends into a whole.

[0033] The magnetic boots 26 are mainly used for the ends of the winding unit 31 to be wound around, forming a back-wound structure. Radial winding grooves 27 are formed between adjacent magnetic boots 26 for the bent portion 31b of the winding unit 31 to be embedded. In addition, the magnetic boots 26 can concentrate axial magnetic flux, increasing the magnetic flux density at the axial air gap 52.

[0034] It should be noted that the axial winding slots 24 and the radial winding slots 27 are in a one-to-one correspondence, that is, each axial winding slot 24 is opposite to the slot opening of a radial winding slot 27, so that the winding unit 31 can pass smoothly between the axial winding slots 24 and the radial winding slots 27.

[0035] Correspondingly, the number of magnetic shoes 26 and stator teeth 23 are the same, and their positions correspond one-to-one. In this embodiment, there are 24 stator teeth 23 and 24 magnetic shoes 26. In the circumferential direction, the stator teeth 23 and magnetic shoes 26 are arranged at 15° intervals.

[0036] See also Figure 4 and Figure 6Each winding unit 31 is wound in a ring shape on a stator tooth 23 and its corresponding magnetic boots 26 at both ends. The main body 31a of the winding unit 31 is embedded in the axial winding grooves 24 on both sides of the stator tooth 23, and the bent portions 31b at both ends of the winding unit 31 are embedded in the radial winding grooves 27 on both sides of the magnetic boots 26. Specifically, the main body 31a of the winding unit 31 is distributed in a straight line along the extension direction of the stator tooth 23. When it reaches the axial end of the stator core 21, the winding unit first bends at nearly 90° towards the axis of rotation, forming a radial transition section perpendicular to the axis. This transition section fits against the side of the magnetic boot 26, passes around the magnetic boot 26, and then bends in the opposite direction at nearly 180°, so that the winding direction forms a U-shaped fold. Then it bends at nearly 90° in the direction parallel to the axis, returning to the main body 31a, and finally passes around the magnetic boot 26 and stator tooth 23 at the other end, forming a complete ring structure.

[0037] This design allows the same armature winding to participate in both radial and axial magnetic circuit coupling simultaneously, eliminating the need for separate windings for each magnetic circuit. When the armature winding is energized, the main body 31a of the winding unit 31, being axially arranged, generates an armature magnetic field primarily distributed radially (according to Ampere's law), forming radial magnetic circuit coupling with the radial permanent magnet group 12 on the inner wall of the rotor core 11. The bent portions 31b at both ends of the winding unit 31, being radially arranged, generate an armature magnetic field primarily distributed axially, forming axial magnetic circuit coupling with the axial permanent magnet group 14 of the rotor end cover 13. Thus, the entire armature winding forms a 3D magnetic flux structure with radial and axial interweaving, allowing the two magnetic circuits to output torque in parallel.

[0038] Because the radial and axial magnetic circuits share the same set of windings, their armature magnetic fields are generated by the same current excitation, naturally possessing the same phase characteristics and exhibiting no phase difference. This phase consistency allows the radial and axial magnetic fluxes to synergistically superimpose in the stator core, yoke, and other magnetically conductive components, rather than canceling each other out. This strengthens the coupling effect of 3D magnetic flux, improves the utilization efficiency of magnetic field energy, and ensures maximum output torque of the motor. Simultaneously, the shared winding design simplifies the overall structure of the motor, reduces the use of winding materials, and balances performance improvement with motor compactness and economy.

[0039] like Figure 5 As shown, the end of the magnetic shoe 26 away from the magnetic yoke 25 protrudes outwards to form an axial boss 26a. The side of the axial boss 26a forms a limiting feature for the winding unit 31, so that the bent portion 31b of the winding unit 31 will not come out of the axial winding slot 24. The outer ends of the stator teeth 23 also protrude to both sides to form radial bosses 23a, which limit the main body portion 31a of the winding unit 31 and prevent the main body portion 31a from coming out.

[0040] like Figure 2 As shown, an axial air gap 52 is formed between the end face of the magnetic shoe 26 and the axial permanent magnet assembly 14. A radial air gap 51 is formed between the outer end face of the stator tooth 23 and the radial permanent magnet assembly 12. The radial magnetic flux path starts from one of the radial permanent magnets in the radial permanent magnet assembly 12, passes through the radial air gap 51 into the stator tooth 23, is transmitted to the adjacent stator tooth via the stator core yoke, then passes through the radial air gap 51, passes through adjacent radial permanent magnets with opposite polarity, and returns to the initial radial permanent magnet via the rotor core, forming a radial closed magnetic flux. The axial magnetic flux path starts from one of the axial permanent magnets in the axial permanent magnet assembly 14, passes through the axial air gap 52 into the magnetic shoe 26, flows through the magnetic yoke 25, then flows through the magnetic yoke 25 to the adjacent magnetic shoe 26, passes through the axial air gap 52, passes through adjacent axial permanent magnets with opposite polarity, and returns to the initial axial permanent magnet via the rotor end cover 13, forming an axial closed magnetic flux.

[0041] Preferably, the size ratio of the axial air gap 52 to the radial air gap 51 is 1 to 2. For example, the axial air gap 52 and the radial air gap 51 can both be 1 mm. The uniform air gap ensures the uniformity of magnetic flux transmission, effectively reduces the magnetic field distortion caused by uneven air gap, reduces torque pulsation, and makes the motor run more smoothly.

[0042] The working principle of this motor is as follows: When three-phase alternating current is applied to the armature winding, each winding unit will generate a periodically changing armature magnetic field. Since the main body of the winding unit is embedded in the axial winding slot and the bent part is embedded in the radial winding slot, the generated armature magnetic field will cover both the radial and axial directions simultaneously, and will couple with the radial excitation magnetic field of the radial permanent magnet group and the axial excitation magnetic field of the axial permanent magnet group.

[0043] Because there is a fixed phase difference between the armature magnetic field and the excitation magnetic field generated by the permanent magnet, the two magnetic fields are always in a dynamic equilibrium of attraction and repulsion. In the radial dimension, the armature magnetic field interacts with the excitation magnetic field of the radial permanent magnet, generating a radial magnetic pull component; in the axial dimension, the armature magnetic field interacts with the excitation magnetic field of the axial permanent magnet, generating an axial magnetic pull component. The combination of these two components drives the rotor assembly to rotate continuously around the stator and shaft, forming a driving torque.

[0044] Compared to traditional external rotor permanent magnet synchronous motors with a single radial magnetic field, the motor in this embodiment constructs a 3D magnetic flux path, enabling the radial and axial magnetic fields to work together. This fully utilizes the effective length of the windings and the internal space of the motor, allowing it to output greater electromagnetic torque within the same volume and significantly improving the power density of the motor.

[0045] See also Figure 2The rotating shaft 4 serves as a fixed support component for the stator assembly 2. It is coaxially inserted into the central hole of the stator core 21 and rigidly fixed to the stator core 21 via a key connection or interference fit, ensuring that the rotating shaft 4 and the stator assembly 2 do not rotate relative to each other. At the same time, the two axial ends of the rotating shaft 4 are rotatably connected to the central holes of the two rotor end covers 13 via bearings 41, enabling the rotor assembly 1 to rotate stably around the rotating shaft 4 and the stator assembly 2.

[0046] In this embodiment, the radial permanent magnet group 12 includes a plurality of radial permanent magnets. These radial permanent magnets are uniformly distributed on the inner wall of the rotor core in a circumferential direction. The polarity directions of adjacent radial permanent magnets are opposite, that is, they are arranged alternately with the N pole facing outward and the S pole facing outward along the circumferential direction, so as to form a uniform and alternating radial magnetic field between the inner side of the rotor and the stator teeth.

[0047] Similarly, the axial permanent magnet assembly 14 includes multiple axial permanent magnets. The axial permanent magnets are evenly distributed around the circumference on the surface of the rotor end cover 13 facing the rotor core 11. The polarity directions of adjacent axial permanent magnets are opposite, that is, they are arranged alternately with the N pole facing the stator side and the S pole facing the stator side along the circumference, so as to form an alternating axial magnetic field between the rotor end cover 13 and the magnetic shoe 26.

[0048] This symmetrical arrangement ensures that the air gap magnetic flux density varies uniformly along the circumference, avoiding torque pulsation caused by uneven magnetic field distribution. At the same time, it provides a stable excitation magnetic field for the armature winding, reduces local magnetic flux saturation in the iron core, lowers hysteresis loss and eddy current loss, and improves the smoothness of motor operation.

[0049] To achieve spatial in-phase superposition of the radial and axial magnetic fields, the radial permanent magnet group 12 and the axial permanent magnet group 14 can be designed to contain an equal number of permanent magnets. In this embodiment, the radial permanent magnet group 12 contains 16 radial permanent magnets 12a, and the axial permanent magnet group 14 also contains 16 axial permanent magnets 14a. Every two adjacent opposite-pole permanent magnets form a pair of poles, so both the radial permanent magnet group 12 and the axial permanent magnet group 14 include 8 pairs of poles, which corresponds exactly to the number of winding units 31 contained in each phase of the armature winding 22.

[0050] Furthermore, the radial permanent magnets 12a and axial permanent magnets 14a can be aligned, meaning the center line of the magnetic poles of each radial permanent magnet 12a and the center line of the magnetic poles of one axial permanent magnet 14a lie in the same radial plane. This ensures that the spatial positions of the radial and axial magnetic fields correspond precisely, guaranteeing that the two magnetic fields are superimposed in phase in key magnetically conductive components such as the stator teeth 23 and the magnetic yoke 25. This avoids the cancellation of magnetic fields caused by spatial misalignment, strengthens the coupling effect of 3D magnetic flux, and improves the output efficiency of electromagnetic torque.

[0051] like Figure 8As shown, within the same radial plane, the polarity of the radial permanent magnet 12a facing the stator assembly is consistent with the polarity of the corresponding axial permanent magnet 14a facing the stator assembly. That is, when the radial permanent magnet 12a is N-pole facing the stator, the corresponding axial permanent magnet 14a is also N-pole facing the stator, and vice versa. This design conforms to the direction of the magnetic field generated by a single winding unit 31 (according to the right-hand rule, the magnetic field generated by a single winding unit is either outward or inward, whether in the middle section or the end bending section), thereby synergistically enhancing the magnetic field superposition effect and improving coupling efficiency.

[0052] Furthermore, since the two ends of the winding unit 31 are symmetrically bent into bending portions 31b, armature magnetic fields with opposite directions and the same density are generated at both ends. The axial permanent magnets 14a are also symmetrically arranged at both ends of the axial direction. Therefore, the two ends of the winding unit 31 of the axial direction will be subjected to attractive or repulsive forces of the same magnitude but opposite directions. The attractive or repulsive forces at both ends will cancel each other out, thereby solving the offset problem caused by axial instability of the pure axial flux motor.

[0053] Preferably, the magnetic shoe 26 can be designed with a wider outer side and a narrower inner side, meaning that the width on the side closer to the shaft 4 is smaller than the width on the side farther from the shaft 4. This design can maintain the width of the radial winding groove 27 and adapt to the natural curvature of the winding bend 31b. Especially for flat wire windings, the flat wire needs to maintain a smooth transition at the bend to avoid insulation damage. The wider outer side and narrower inner side structure of the magnetic shoe 26 can reserve enough space to accommodate the bending curvature of the flat wire, ensuring the fit between the winding and the magnetic shoe 26, and reducing stress concentration during winding formation.

[0054] In a possible embodiment, the magnetic shoe 26 and the stator tooth 23 can be directly connected to form a whole, and a smooth transition design, such as an arc transition or a slope transition, can be adopted at the corner position (i.e., the junction of the magnetic shoe 26 and the stator tooth 23). This structural design can guide the magnetic lines of force to flow smoothly and reduce the concentration of the magnetic field at the corner. On the other hand, it can provide a regular contact surface for the bending section of the armature winding, reduce the difficulty of the winding process, and ensure the compactness and stability of the winding arrangement.

[0055] Since the rotor assembly 1 rotates at high speed during operation, the axial permanent magnet group 14 will be subjected to a large centrifugal force. In order to prevent it from falling off the surface of the rotor end cover 13 due to the centrifugal force, a suitable mounting groove 13a is processed on the surface of the rotor end cover 13 facing the rotor core 11, corresponding to the distribution position of the axial permanent magnet group 14 in the circumferential direction. Each axial permanent magnet 14a is embedded in the mounting groove 13a and can be bonded and fixed by high-strength epoxy resin.

[0056] To ensure the alignment of the radial permanent magnet 12a and the axial permanent magnet 14a, a limiting structure can be provided at the mating surface of the rotor end cover 13 and the rotor core 11. For example, a positioning boss can be machined on the axial end face of the rotor core 11, and a corresponding positioning groove can be machined on the mating surface of the rotor end cover 13, or a mutually meshing stop structure can be provided along the circumference. This limiting structure can strictly restrict the relative rotation of the rotor end cover 13 in the circumferential direction, ensure the alignment of the axial permanent magnet groups on both ends of the rotor end cover, avoid phase deviation of the magnetic field due to misalignment of the end cover assembly, and ensure efficient coupling of the axial magnetic flux and the armature magnetic field.

[0057] In summary, the motor winding provided in this embodiment creatively uses magnetic boots to guide the winding to back-wound arrangement at the end of the stator core, generating an axial armature magnetic field. At the same time, the leakage magnetic field at the end of the winding in the radial magnetic circuit that was originally not utilized is effectively recovered. The axial armature magnetic field interacts with the axial permanent magnet magnetic field and does work through the axial air gap, providing additional auxiliary energy output for the motor.

[0058] Meanwhile, since the axial armature magnetic field and the radial armature magnetic field share the same armature winding, there is no need to add additional windings or complex phase calibration structures, which can naturally achieve phase synchronization between the two and avoid the magnetic field cancellation problem caused by phase misalignment of multiple windings.

[0059] In addition, this design can also form a hybrid excitation 3D magnetic flux structure that combines radial magnetic circuit and axial magnetic circuit at both ends. The radial magnetic flux and the axial magnetic flux at both ends work together in parallel, which can fully release magnetic field energy in a limited motor space, significantly improve the motor torque density and load capacity, and effectively reduce the size and weight of the motor, with outstanding lightweight effect. It is suitable for scenarios with limited axial space and high torque density requirements.

[0060] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. An external rotor 3D flux permanent magnet synchronous motor, characterized in that, include: The rotor assembly includes a rotor core, a radial permanent magnet assembly, two rotor end caps, and an axial permanent magnet assembly. The rotor core is cylindrical. The radial permanent magnet assembly is fixedly disposed on the inner wall of the rotor core. The rotor end caps are connected to the axial ends of the rotor core. The axial permanent magnet assembly is fixedly disposed on the surface of the rotor end caps facing the rotor core. A stator assembly is coaxially disposed within the rotor core. The stator assembly includes a stator core and an armature winding. Multiple stator teeth are provided on the outer circumferential surface of the stator core, with axial winding slots formed between adjacent stator teeth. Magnetic yokes are connected to the axial ends of both sides of the stator core. Multiple magnetic shoes are provided on the end faces of the magnetic yokes, with radial winding slots formed between adjacent magnetic shoes. The positions of the stator teeth and the magnetic shoes correspond one-to-one. The armature winding includes multiple winding units, each of which is wound in a ring shape on a stator tooth and its corresponding magnetic guide shoes at both ends. The main body of the winding unit is embedded in the axial winding slots on both sides of the stator tooth, and the bent portions at both ends of the winding unit are embedded in the radial winding slots on both sides of the magnetic guide shoes. The winding unit is coupled with the radial permanent magnet group and the axial permanent magnet group to form a 3D magnetic flux path. A rotating shaft is coaxially disposed within the stator assembly and fixedly connected to the stator core. The rotating shaft is connected to the rotor end cover via a bearing.

2. The external rotor 3D flux permanent magnet synchronous motor according to claim 1, characterized in that: The radial permanent magnet group comprises multiple radial permanent magnets, which are evenly distributed around the circumference on the inner wall of the rotor core, with adjacent radial permanent magnets having opposite polarity directions; the axial permanent magnet group comprises multiple axial permanent magnets, which are evenly distributed around the circumference on the surface of the rotor end cover facing the rotor core, with adjacent axial permanent magnets having opposite polarity directions.

3. The external rotor 3D flux permanent magnet synchronous motor according to claim 2, characterized in that: The radial permanent magnet group contains the same number of radial permanent magnets as the axial permanent magnet group contains, and the magnetic pole centerline of each radial permanent magnet is in the same radial plane as the magnetic pole centerline of one axial permanent magnet.

4. The external rotor 3D flux permanent magnet synchronous motor according to claim 3, characterized in that: Both radial permanent magnets and axial permanent magnets in the same radial plane face the stator assembly with the same polarity.

5. The external rotor 3D flux permanent magnet synchronous motor according to claim 1, characterized in that: The end of the magnetic shoe away from the magnetic yoke protrudes outward to form an axial boss. The side of the axial boss forms a limit for the winding unit, and an axial air gap is formed between the end face of the axial boss and the axial permanent magnet assembly.

6. The external rotor 3D flux permanent magnet synchronous motor according to claim 5, characterized in that: The stator tooth extends to both sides away from the axis to form a radial boss. The side of the radial boss forms a limit for the winding unit. A radial air gap is formed between the end face of the radial boss and the radial permanent magnet assembly.

7. The external rotor 3D flux permanent magnet synchronous motor according to claim 6, characterized in that: The radial flux path starts from one of the radial permanent magnets in the radial permanent magnet group, passes through the radial air gap into the stator teeth, is transmitted through the stator core to the adjacent stator teeth, then passes through the radial air gap and the adjacent radial permanent magnets with opposite polarity, and returns to the initial radial permanent magnet through the rotor core, forming a radial closed flux. The axial magnetic flux path starts from one of the axial permanent magnets in the axial permanent magnet group, passes through the axial air gap into the magnetic shoe, is transmitted to the magnetic yoke, then flows through the magnetic yoke through the adjacent magnetic shoe, passes through the axial air gap and adjacent axial permanent magnets with opposite polarity, and returns to the initial axial permanent magnet through the rotor end cover, forming an axial closed magnetic flux. The size ratio of the axial air gap to the radial air gap is 1 to 2.

8. The external rotor 3D flux permanent magnet synchronous motor according to claim 1, characterized in that: The rotor end cover has a mounting groove on the surface facing the rotor core, and the axial permanent magnet assembly is embedded in the mounting groove.

9. The external rotor 3D flux permanent magnet synchronous motor according to claim 1, characterized in that: One of the two rotor end caps is integrally formed with the rotor core, and the other is detachably connected to the rotor core.

10. The external rotor 3D flux permanent magnet synchronous motor according to claim 9, characterized in that: A limiting structure is provided at the detachable connection position between the rotor end cover and the rotor core, the limiting structure being used to restrict the position of the rotor end cover in the circumferential direction.

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