Permanent magnet brushless motor and manufacturing method thereof, multi-axis aircraft and robot

Abstract

Embodiments of the present disclosure provide a permanent magnet brushless motor and a manufacturing method thereof, a multi-axis aircraft and a robot. The permanent magnet brushless motor is a fractional slot outer rotor motor, which comprises a stator and a rotor. The stator comprises a stator core and a stator winding, the stator winding is a non-interleaved concentrated winding with a span of 1. The rotor comprises a permanent magnet and a rotor core. The stator core comprises a stator yoke and a stator tooth portion, the stator tooth portion comprises a plurality of stator teeth arranged on the stator yoke, and each stator tooth is provided with an insulation layer. The stator winding comprises a plurality of winding coils formed by machine winding, and each winding coil is symmetrically arranged on the corresponding stator tooth with the radial center axis of the stator tooth as the axis of symmetry. The motor of the embodiments of the present disclosure can significantly improve the slot fill factor, motor constant and output power density of the motor while ensuring low cogging torque and smooth operation of the motor.

Description

Technical Field

[0001] At least one embodiment of this disclosure relates to a permanent magnet brushless motor and a method for manufacturing the same, a multi-axis aircraft, and a robot. Background Technology

[0002] In recent years, multi-rotor aircraft, represented by multi-rotor drones, have developed rapidly and play an important role in fields such as plant protection, aerial photography, delivery, reconnaissance, rescue, and surveying. Multi-rotor aircraft place high demands on their motors. With the same output power, lighter and more efficient motors mean increased payload or battery capacity, thereby improving the aircraft's endurance and performance.

[0003] The main obstacles to the advancement of small brushless motors are design and manufacturing challenges. Many performance-enhancing techniques used in medium and large motors are not applicable to small motors. Therefore, designing practically manufacturable high-performance small motors remains a significant challenge. Summary of the Invention

[0004] The embodiments of this disclosure provide a permanent magnet brushless motor and its manufacturing method, a multi-axis aircraft, and a robot, which can significantly improve the slot fill factor, motor constant per unit mass, and output power density of the motor, and are suitable for small motors.

[0005] In a first aspect, embodiments of this disclosure provide a permanent magnet brushless motor, which is a fractional-slot external rotor motor. The motor includes a stator and a rotor. The stator includes a stator core and a stator winding, wherein the stator winding is a non-interlaced concentrated winding with a span of 1. The rotor includes a permanent magnet and a rotor core, wherein the permanent magnet is used to generate a rotating magnetic field for excitation. The stator core includes a stator yoke and a stator tooth, wherein the stator tooth includes a plurality of stator teeth disposed on the stator yoke, and each stator tooth has an insulating layer on its surface. The stator winding includes a plurality of winding coils formed by machine winding, wherein each of the plurality of winding coils is symmetrically disposed on the corresponding stator tooth with the radial central axis of the corresponding stator tooth as the axis of symmetry.

[0006] For example, each of the winding coils includes multiple layers of wiring from the inside out, the number of layers being n, where n is an even number; the entry point of the winding coil is located on the side close to the stator yoke.

[0007] For example, the conductor of each winding coil is a circular wire with a circular cross-section or a square wire with an approximately square cross-section, wherein the outer diameter of the circular wire with its sheath is dc, and the side length of the square wire with its sheath is dc.

[0008] when When, the range of values ​​for dc is:

[0009]

[0010] when or When, the range of values ​​for dc is:

[0011]

[0012] in or

[0013] q is half the arc length between the tooth ends of adjacent stator teeth away from the stator yoke in the axial cross section of the stator core, and p is half the arc length between the tooth roots of adjacent stator teeth near the stator yoke in the axial cross section of the stator core.

[0014] For example, the width of the stator teeth is the same from the tooth tip away from the stator yoke to the tooth root near the stator yoke; or the width of the stator teeth gradually increases from the tooth tip away from the stator yoke to the tooth root near the stator yoke.

[0015] For example, the surface insulation layer of each stator tooth is an electrophoretic surface treatment layer or a vapor deposition surface treatment layer.

[0016] For example, the edge of the stator tooth extending from the tooth root to the tooth tip has a chamfered structure.

[0017] For example, the width of the narrowest part of the stator tooth is greater than or equal to 25% of the outer circumference of the outer diameter of the stator / N, and less than or equal to 60% of the outer circumference of the outer diameter of the stator / N, where N is the number of stator teeth.

[0018] For example, the width of the widest part of the stator tooth is less than or equal to 3.2 mm.

[0019] For example, the thickness of the stator yoke is greater than or equal to 60% of the width of the narrowest part of the stator tooth, and less than or equal to 175% of the width of the narrowest part of the stator tooth.

[0020] For example, an air gap is formed between the stator and the rotor, and the average air gap distance of the motor is less than or equal to 0.6% of the outer diameter of the stator.

[0021] For example, the outer diameter of the stator core is less than or equal to 150 mm.

[0022] For example, the axial height of the stator core is less than or equal to 25% of the outer diameter of the stator core.

[0023] For example, the average radial thickness of the permanent magnet is less than or equal to 20 times the average air gap distance, and greater than or equal to 4.5 times the average air gap distance.

[0024] For example, the radial thickness of the rotor core is greater than or equal to 50% of the radial thickness of the permanent magnet, and less than or equal to 175% of the radial thickness of the permanent magnet.

[0025] For example, the motor is a three-phase motor, and the greatest common divisor C of the number of stator teeth / 3 and the number of permanent magnet poles is greater than or equal to 2 and less than or equal to 8.

[0026] For example, the motor is a three-phase motor, and the stator winding coils with the number of stator teeth / C / 3 are connected in series to form the smallest unit. The smallest units are connected in series, in parallel, or in a mixed series-parallel connection to form any one phase of the stator winding.

[0027] For example, the ratio of the number of poles of the permanent magnet to the number of teeth of the stator is greater than or equal to 0.78 and less than or equal to 1.34.

[0028] Secondly, embodiments of this disclosure also provide a method for manufacturing the above-described permanent magnet brushless motor, comprising: preparing a stator core; preparing the winding coil of the stator winding, comprising: using a winding machine to wind enameled wire on a bobbin to obtain a hollow coil; fitting and fixing the hollow coil onto the stator core; and performing electrical connection of the coil, comprising: connecting the winding coil according to the connection method specified for the motor winding.

[0029] Thirdly, embodiments of this disclosure also provide a multi-rotor aircraft, including a permanent magnet brushless motor as described in any of the first aspects.

[0030] Fourthly, embodiments of this disclosure also provide a robot including a permanent magnet brushless motor as described in any of the first aspects.

[0031] This disclosure provides a permanent magnet brushless motor and its manufacturing method, a multi-axis aircraft, and a robot. The permanent magnet brushless motor's winding coil, after being machine-wound, is fitted onto the stator teeth, thereby avoiding interference during coil winding and improving slot fill factor. Further, in this disclosure, based on half the arc length between the tooth ends of adjacent stator teeth away from the stator yoke in the axial cross-section of the stator core and half the arc length between the tooth roots of adjacent stator teeth near the stator yoke in the axial cross-section of the stator core, and considering the number of winding layers, the range of the outer diameter or side length of the conductor of the winding coil is determined. This allows the size of the conductor used for the winding coil to be determined based on the stator core, etc. Motors wound with such conductors can significantly improve slot fill factor, torque density, and motor constant per unit mass. Furthermore, the determination of the outer diameter or side length of the above-mentioned conductors, along with other motor structural parameters such as the width of the narrowest part of the stator teeth, the average air gap distance, the outer diameter and inner diameter of the stator, and the motor manufacturing process, optimizes the size and structure of the motor. This ensures that the wound coils are consistent, compact, and safe, guarantees stable assembly and fit between the coils and the motor, and maximizes the use of motor slot space. While ensuring low cogging torque and smooth motor operation, it also results in high slot fill factor and low DC and AC copper losses in mass-produced motors, thereby improving the torque density and motor constant per unit mass of the motor. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure.

[0033] Figure 1 This is a schematic diagram of the structure of a permanent magnet brushless motor provided in an embodiment of this disclosure;

[0034] Figure 2 This is a schematic diagram of the structure of the permanent magnet brushless motor stator provided in an embodiment of this disclosure;

[0035] Figure 3 This is another structural schematic diagram of the permanent magnet brushless motor stator provided in an embodiment of this disclosure;

[0036] Figure 4A A top view of a winding coil provided in an embodiment of this disclosure;

[0037] Figure 4B A cross-sectional view of the winding coil along the DD line provided in an embodiment of this disclosure;

[0038] Figure 4C An overall view of the winding coil provided in an embodiment of this disclosure;

[0039] Figure 5 This is a simulation diagram showing the relationship between the narrowest stator tooth width / (circumference of the outer circle containing the stator's outer diameter / number of teeth) and the motor constant per unit weight in an embodiment of this disclosure.

[0040] Figure 6 This is a schematic diagram illustrating the simulation effect of the thickness of the stator yoke / width at the narrowest point of the stator teeth and the motor constant per unit weight in an embodiment of the present disclosure.

[0041] Figure 7 This is a schematic diagram illustrating the simulation effect of the ratio of the average air gap distance to the stator outer diameter of the motor in an embodiment of this disclosure, and the motor constant per unit weight.

[0042] Figure 8 This is a schematic diagram illustrating the simulation effect of the ratio of the average radial thickness to the average air gap distance of the permanent magnet of the motor in an embodiment of this disclosure, and the motor constant per unit weight.

[0043] Figure 9 This is a schematic diagram illustrating the simulation effect of the ratio of the radial thickness of the rotor core to the radial thickness of the permanent magnet in an embodiment of the present disclosure, and the motor constant per unit weight.

[0044] Figure 10 This is a schematic diagram illustrating the simulation effect of the ratio of the axial height h of the stator core to the outer diameter of the stator core of the motor according to an embodiment of the present disclosure, and the motor constant per unit weight.

[0045] Figure 11 This is a schematic diagram illustrating the relationship between the slot fill factor and the outer diameter or side length dc of the belt in an embodiment of the present disclosure; and

[0046] Figure 12 This is a flowchart illustrating a method for manufacturing an electric motor according to an embodiment of the present disclosure.

[0047] 100-Motor, 1-Stator, 10-Stator core, 101-Stator yoke, 102-Stator tooth, 1021-Tooth tip, 1022-Tooth root, 1023-Edge of tooth tip extending to tooth root, 103-Radial central shaft, 104-Half of stator slot, 110a-Circumference of winding coil near tooth tip, 110b-Circumference of winding coil near tooth root, 11-Winding coil, 2-Rotor, 20-Rotor core, 21-Permanent magnet. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0049] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0050] For motors used in small torque applications and drones, the performance and efficiency of the motor can be measured by the motor constant, which is defined as follows:

[0051]

[0052] Multi-rotor aircraft, such as multi-rotor drones, use stators with shoe-shaped windings for their motors. The winding coils are wound using a special stator winding machine, which greatly limits the slot fill factor of the motor. Taking common products on the market as an example, the slot fill factor of a typical multi-rotor aircraft motor is only about 30%, resulting in lower power output per unit weight and per unit volume, lower motor constant, and lower motor efficiency.

[0053] While there is considerable research in academia on improving the torque performance of motors, most studies focus on medium or large motors, primarily used in air compressors, industrial servos, new energy vehicles, and wind turbines. Research on improving the torque performance and lightweighting of small motors and motors specifically designed for drones and high-performance robots is relatively limited. Furthermore, the torque-volume density metric widely used in academia is not entirely suitable for small motors. In addition, motors reported in academia often lack the feasibility for mass production due to factors such as cost, complexity, and consistency. Some seemingly promising and high-performance designs lack practical application conditions, let alone miniaturized motors.

[0054] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of this disclosure provides a permanent magnet brushless motor 100, which is a fractional-slot external rotor motor. The motor includes a stator 1 and a rotor 2. The stator 1 includes a stator core 10 and a stator winding, which is a non-interlaced concentrated winding with a span of 1. The rotor 2 includes a permanent magnet 21 and a rotor core 20, wherein the permanent magnet 21 is used to generate a rotating magnetic field for excitation. The stator core 10 includes a stator yoke 101 and a stator tooth portion. The stator tooth portion includes a plurality of stator teeth 102 disposed on the stator yoke portion, and each stator tooth 102 has a surface insulating layer on its surface. The stator winding includes a plurality of winding coils 11 formed by machine winding. Each of the plurality of winding coils 11 is symmetrically disposed on the corresponding stator tooth 102 with the radial central axis 103 of the corresponding stator tooth 102 as the axis of symmetry.

[0056] For example, the surface insulation layer provided on the surface of each stator tooth 102 can ensure the insulation of the stator winding and stator core, preventing leakage. In an embodiment of this disclosure, the surface insulation layer can be an electrophoretic surface treatment layer, that is, an electrophoretic surface treatment layer is formed on the surface of each stator tooth as a surface insulation layer through electrophoretic treatment. Electrophoretic (electro-coating or E-coating) surface treatment is also known as electrophoretic coating treatment. In another embodiment of this disclosure, the surface insulation layer can be a vapor deposition surface treatment layer. Vapor deposition surface treatment refers to the process of forming a film on the surface of a workpiece using gaseous substances. Vapor deposition can be divided into physical vapor deposition and chemical vapor deposition. This disclosure does not limit the method and type of vapor deposition. Alternatively, the surface insulation layer can have both electrophoretic surface treatment and vapor deposition surface treatment. Vapor deposition or electrophoretic surface treatment is stable, has good consistency and adhesion, good pressure resistance, and a thin cover layer, which can leave more space for copper wires and significantly improve the motor slot fill factor.

[0057] For example, after the winding coil 11 is formed by machine winding, it can be fitted onto the stator teeth 102. The machine-processed winding coil 11 can be isolated, that is, each coil has two broken leads, or it can be several winding coils directly connected by the machine.

[0058] For example, in some embodiments of this disclosure, the connection between winding coils can be accomplished by soldering to a printed circuit board or by soldering wires over the air. The embodiments of this disclosure do not limit the method of connection between winding coils.

[0059] One winding technique involves directly winding the coil onto the stator teeth using a specialized stator winding machine. This process, however, can cause interference between the stator teeth and the winding coils on them, resulting in gaps between adjacent coils often exceeding 2-3 mm. Furthermore, the irregular winding arrangement of commonly used robot motors significantly impacts the motor's slot fill factor. In the embodiments of this disclosure, the winding coils are wound and then fitted onto the stator teeth. This eliminates any interference during the winding process, making it easier to achieve the design requirements and significantly reducing the gaps between adjacent coils, thereby greatly improving the motor's slot fill factor. Moreover, in the embodiments of this disclosure, the machine-wound coils are neatly arranged with a high fill factor, further increasing the motor's torque density, motor constant, and output power density, thus enhancing motor performance. For small-sized inorganic humans and robots, such high-performance motors can further improve device performance.

[0060] For example, in embodiments of this disclosure, such as Figure 2 As shown, the width of the stator teeth 102 is the same from the tooth tip 1021 away from the stator yoke 101 to the tooth root 1022 near the stator yoke 101. This facilitates the manufacturing of the corresponding winding coils 11 and improves space utilization, thereby increasing the motor constant per unit weight. It is understandable that in some examples, the stator tooth width can gradually increase from the tooth tip 1021 away from the stator yoke 101 to the tooth root 1022 near the stator yoke 101. It should be noted that in commonly used UAV motors, the stator teeth are generally T-shaped (i.e., the stator teeth have a boot-like structure). Stator teeth with boot-like structures affect the size of the winding coil cavity, thus reducing the space utilization of the winding coil. In the embodiments of this disclosure, the stator teeth are not formed with boot-like structures. The elimination of the boot-like structures improves the space utilization of the winding coil, which in turn helps to further increase the motor constant per unit weight and improve motor performance.

[0061] For example, in the embodiments of this disclosure, the stator core 10 can be a one-piece core. It should be noted that a one-piece core differs from a core assembled from multiple modules or parts; a core formed by stacking integral laminations also falls under the category of one-piece cores in the embodiments of this disclosure. For example, the stator core 10 can be formed by stacking silicon steel sheets or soft magnetic material sheets. One-piece cores are easy to process, have mature technology, and are low in cost.

[0062] For example, in an embodiment of this disclosure, the edge 1023 of the stator tooth 102 extending from the tooth tip to the tooth root has a chamfered structure. Figure 2 As shown, the stator teeth 102 have chamfered edges extending from the tooth root 1022 to the tooth tip 1021. In some embodiments, the tooth tip edges and / or tooth roots of the stator teeth 102 are also chamfered. Due to the limitations of the mechanical properties of the material, the inner wall of the winding coil cannot be made into a perfect right angle, and will form a certain rounded corner. The chamfered stator teeth 102 can adapt to the rounded corners of the inner wall of the coil, reduce unnecessary copper in the motor, and improve the operating efficiency of the motor. It should be noted that in the embodiments of this disclosure, the chamfered structure is a structure formed by processing sharp edges into non-sharp edges. The non-sharp edge after chamfering can be an obtuse angle edge, a rounded edge, or other non-sharp edges, and the embodiments of this disclosure do not limit this.

[0063] For example, in embodiments of this disclosure, to further improve the firmness of the connection between the winding coil 11 and the stator tooth 102, the stator 1 may further include an adhesive layer; the winding coil 11 is fixed to the stator tooth 102 by the adhesive layer. The adhesive layer may be formed by curing glue that is uniformly applied to the surface of the stator tooth 102 or the inner surface of the winding coil 11. Specifically, glue may be uniformly applied to part or all of the surface of the stator tooth 102, and then the winding coil 11 is fitted onto the stator tooth 102. After the glue cures, an adhesive layer is formed, fixing the winding coil 11 to the stator tooth 102 and preventing it from easily loosening. In some embodiments of this disclosure, the adhesive layer may be formed by curing glue applied to and covering the axial surface of the winding coil 11 already mounted on the stator tooth 102, fixing the winding coil 11 to the stator tooth 102 by the relative position of the winding coil 11. This disclosure does not limit the specific implementation form and method of the adhesive layer.

[0064] For example, in the embodiments of this disclosure, the size and structure of the motor are also designed to improve motor performance, enhance manufacturing feasibility, and obtain excellent motor constants. Examples of the motor's size and structure are as follows:

[0065] In the motor of the embodiments of this disclosure, see... Figure 2 The width of the stator tooth 102 is w, the diameter of the circle containing the outer diameter of the stator core 10 is d2, and the circumference of the circle containing the outer diameter of the stator core 10, which is also the circumference of the outer circle containing the outer diameter of the stator 1, d2×π, is denoted as p1. The width of the narrowest part of the stator tooth 102 can be greater than or equal to 25% of the circumference p1 / N of the outer diameter of the stator, and can be less than or equal to 60% of the circumference p1 / N of the outer diameter of the stator, where N is the number of stator teeth 102.

[0066] For motors where the width of the stator tooth 102 is the same from the tooth tip 1021 to the tooth root 1022, the width of the narrowest part of the stator tooth 102 is the width of the stator tooth 102. However, for motors where the width of the stator tooth 102 is not the same everywhere, the width of the narrowest part of the stator tooth 102 is the minimum width of the stator tooth.

[0067] For example, in an embodiment of this disclosure, the number of stator teeth 102 can be 48. Figure 5 The diagram illustrates the simulation results of the ratio of the narrowest point width of the stator teeth to the number of teeth (the outer circumference of the stator's outer diameter) versus the motor constant per unit weight when the number of stator teeth N is 48. Figure 5 As shown, when the width of the narrowest part of the stator tooth 102 is greater than or equal to 25% of the outer circumference p1 / N of the stator's outer diameter and less than or equal to 60% of the outer circumference p1 / N of the stator's outer diameter, the motor constant per unit weight is approximately To date Compared with existing motors, the motor of the present disclosure embodiment with the above structure significantly improves the motor constant per unit weight and enhances the output efficiency of the motor.

[0068] Furthermore, in the motor of the embodiments of this disclosure, see... Figure 2 The thickness of the stator yoke 101 is L, which can be set to be greater than or equal to 60% of the width of the narrowest part of the stator tooth, and less than or equal to 175% of the width w of the narrowest part of the stator tooth. Figure 6 This diagram illustrates the simulation results of the stator yoke thickness / narrowest stator tooth width versus the motor constant per unit weight when the number of stator teeth N is 48. Figure 6 As shown, when the thickness of the stator yoke is greater than or equal to 60% of the narrowest width of the stator teeth and less than or equal to 175% of the narrowest width w of the stator teeth, the motor constant per unit weight is approximately To date Compared with existing motors, the motor of the present disclosure with the above structure significantly improves the motor constant per unit weight and enhances the output efficiency of the motor. It should be noted that in some embodiments, when the thickness of the stator yoke varies with the angle, the thickness of the stator yoke should be understood as the average radial thickness or the equivalent radial thickness of the stator yoke in the magnetic circuit.

[0069] Furthermore, in the motor of the embodiments of this disclosure, see... Figure 1 An air gap is formed between the stator 1 and the rotor 2, and the average air gap distance of the motor is g. The average air gap distance g of the motor can be less than or equal to 0.6% of the outer diameter d2 of the stator. Figure 7A schematic diagram illustrating the simulation effect of the ratio of the average air gap to the stator outer diameter of the motor according to an embodiment of this disclosure, and the motor constant per unit weight. For example... Figure 7 As shown, with the increase of the ratio of the average air gap to the stator outer diameter, the motor constant per unit weight tends to gradually decrease. When the average air gap distance g of the motor is less than or equal to 0.6% of the stator outer diameter d2, the motor constant per unit weight is greater than or equal to... Compared with existing motors, motors with the above structure significantly improve the motor constant per unit weight and enhance the output efficiency of the motor.

[0070] Furthermore, in the motor of the embodiments of this disclosure, see... Figure 1 The average radial thickness of the permanent magnet 21 is t. The average radial thickness t of the permanent magnet 21 can be less than or equal to 20 times the average air gap distance g, and can be greater than or equal to 4.5 times the average air gap distance g. Figure 8 A simulation diagram illustrating the ratio of the average radial thickness of the permanent magnet to the average air gap distance and the motor constant per unit weight is shown. Figure 8 As shown, when the ratio of the average radial thickness of the permanent magnet to the average air gap distance is between 4.5 and 20, the motor constant per unit weight can be... arrive Compared with existing motors, motors with the above structure significantly improve the motor constant per unit weight and enhance the output efficiency of the motor.

[0071] Furthermore, in the motor of the embodiment of this disclosure, the radial thickness of the rotor core 20 is dr, which can be greater than or equal to 50% of the radial thickness t of the permanent magnet 21 and can be less than or equal to 175% of the radial thickness t of the permanent magnet. Figure 9 A simulation diagram illustrating the ratio of the radial thickness of the rotor core to the radial thickness of the permanent magnet in relation to the motor constant per unit weight is shown. Figure 9 As shown, when the ratio of the radial thickness of the rotor core to the radial thickness of the permanent magnet varies between 0.50 and 1.73, the motor constant per unit weight can be... arrive Compared with existing motors, motors with the above structure significantly improve the motor constant per unit weight and enhance the output efficiency. It should be noted that in some embodiments, when the radial thickness of the rotor core or the radial thickness of the permanent magnet varies with the angle, the radial thickness of the rotor core or the radial thickness of the permanent magnet should be understood as the average radial thickness or the equivalent radial thickness in the magnetic circuit.

[0072] In the motor of the embodiments of this disclosure, the outer diameter d2 of the stator core 10 can be less than or equal to 150 mm.

[0073] In the motor of the embodiments of this disclosure, the axial height h of the stator core 10 can be less than or equal to 25% of the outer diameter d2 of the stator core. Figure 1 , Figure 2 and Figure 3 In the figure, the axial height h is the height of the stator core 10 perpendicular to the plane of the paper. Figure 10 A simulation diagram illustrating the ratio of the axial height h of the stator core to the outer diameter of the stator core and the motor constant per unit weight is shown. For example... Figure 10 As shown, as the ratio of the axial height h of the stator core to the outer diameter of the stator core gradually increases, the motor constant per unit weight gradually decreases. When the ratio of the axial height h of the stator core to the outer diameter of the stator core is less than 0.25, the motor constant per unit weight can be greater than... Compared with existing motors, motors with the above structure significantly improve the motor constant per unit weight and enhance the output efficiency of the motor.

[0074] It should be noted that the structural dimensions and other settings in the embodiments disclosed herein were proposed by the inventors after comprehensive consideration of factors such as ease of manufacturing, electromagnetic performance of the motor, actual operating conditions, and application scenarios. Motors with the aforementioned dimensions and structure can reduce the difficulty of motor manufacturing, processing, and assembly, and are beneficial for improving slot fill factor and increasing air gap area, thereby increasing the torque density of the permanent magnet brushless motor and improving motor performance.

[0075] In embodiments of this disclosure, the width of the widest part of the stator teeth can be less than or equal to 3.2 mm. This reduces the amount of ineffective end windings, improving the motor's operating efficiency and torque performance.

[0076] In embodiments of this disclosure, each stator tooth is fitted with a winding coil, such as... Figure 4A , 4B As shown in 4C, Figure 4A A top view of the winding coil 11 is shown. Figure 4B A cross-sectional view of the winding coil taken along the DD line is shown. Figure 4C A general view of the winding coil 11 is shown. For each stator tooth, the winding coil 11 forms several layers of wire from the inside out, wherein the number of winding coil layers n is an even number, and the entry point of the winding coil is on the side near the stator yoke. It should be noted that the number of wire layers refers to the maximum number; in some areas, the number of wire layers can be less than n, for example, n-1 layers. "From the inside out" means from the center of the stator tooth outwards. Figure 4BAs shown, the number of winding coil layers from the inside out can be, for example, four layers. It should be noted that the number of winding layers refers to the maximum number of layers; in some areas, the number of winding layers can be less than four. Even-numbered winding layers keep the more fragile and easily detached input and output wires of the wound coil away from the rotor, thus preventing the rotor from contacting the wires and causing damage during operation.

[0077] In embodiments of this disclosure, such as Figure 4A , Figure 4B , Figure 2 As shown, the conductor of each winding coil is a circular wire with a circular cross-section or a square wire with an approximately square cross-section. The outer diameter of the circular wire with its sheath is dc, and the side length of the square wire with its sheath is dc.

[0078] when When, the range of values ​​for dc is:

[0079]

[0080] when or When, the range of values ​​for dc is:

[0081]

[0082] in or

[0083] Where q is half the arc length between the tooth ends 1021 of adjacent stator teeth away from the stator yoke in the axial cross section of the stator core, and p is half the arc length between the tooth roots 1022 of adjacent stator teeth near the stator yoke in the axial cross section of the stator core.

[0084] It should be noted that, due to limitations in the manufacturing process, the endpoints of p and q may have rounded corners or chamfers, resulting in a larger arc length at the opening of the actual stator core or a smaller arc length at the connection of adjacent stator teeth. In this case, the values ​​of p and q are hypothetical arc lengths assuming no rounded corners or chamfers. Due to limitations in the manufacturing process, the actual cross-sectional shape of the square line may be a rounded rectangle with similar length and width.

[0085] In embodiments of this disclosure, such as Figure 2 As shown, half of the stator slot 104 that can accommodate the conductor can be approximated as a right trapezoid. The cross-section of the coil can be roughly divided into a wide portion and a narrow portion; maximizing the slot fill factor means maximizing the sum of the areas of the wide and narrow portions. Based on this, a mathematical model can be established, revealing that to achieve the highest slot fill factor, the conductor dimensions need to satisfy certain relationships. Considering factors such as manufacturing errors, the discontinuity of the slot fill factor as a function, and errors introduced by model approximation, the above range is obtained as the range of values ​​for dc.

[0086] For example, for further clarification, in one example of this disclosure, q is 1.57, p is 1.02, and the conductor cross-section is circular. And when n=2, The conductor dimensions are: 0.4876 ≤ dc ≤ 0.5406, corresponding to a slot fill factor of 0.61; when And when n=4, The conductor dimensions are: 0.3128 ≤ dc ≤ 0.3468, corresponding to a slot fill factor of 0.67. When... When n=2, The wire diameter range is: 0.5436 ≤ dc ≤ 0.6027, corresponding to a slot fill factor of 0.64; when And when n=4, The wire diameter range is: 0.3435≤dc≤0.3808, corresponding to a slot fill factor of 0.74.

[0087] Therefore, the ranges of dc obtained from 0.4876≤dc≤0.5406, 0.3128≤dc≤0.3468, 0.5436≤dc≤0.6027, 0.3435≤dc≤0.3808, and n taking even numbers such as 6, 8, and 10, are all possible values ​​for the conductor dimension dc. It should be noted that, for ease of comparison, this embodiment calculates the slot fill factor as the ratio of the sheathed conductor cross-sectional area to the slot area.

[0088] In embodiments of this disclosure, Figure 11 The relationship between slot fill factor and belt outer diameter or belt side length dc is shown, with the shaded area representing the range proposed in this embodiment. Following the selection method provided in this embodiment, the slot fill factor can be significantly improved, reaching a maximum of 0.75, which is a significant improvement compared to existing technologies. This is of great importance for reducing motor copper losses and improving operating efficiency and torque performance.

[0089] In this embodiment, as Figure 4C As shown, from near the stator yoke 101 to far away from the stator yoke 101, the circumference of the winding coil on the stator tooth 102 tends to increase or remain unchanged. That is, the circumference 110b of the winding coil near the tooth root 1022 can be less than or equal to the circumference 110a of the winding coil near the tooth end 1021.

[0090] It should be noted that the structural dimensions and other settings in this embodiment were proposed by the inventors after comprehensive consideration of factors such as ease of manufacturing, electromagnetic performance of the motor, actual operating conditions, and application scenarios. This embodiment optimizes the relevant dimensions of the motor to ensure the consistency, compactness, and safety of the wound coils, guaranteeing stable assembly and fit between the coils and the motor, and maximizing the use of motor slot space. While ensuring low cogging torque and smooth motor operation, it also results in high slot fill factor and low DC and AC copper losses in mass-produced motors, thereby improving the motor's torque density and motor constant per unit mass.

[0091] like Figure 1 As shown in the embodiments of this disclosure, a permanent magnet 21 is disposed on the inner surface of the rotor core 20. The permanent magnet 21 may be made of neodymium iron boron magnet.

[0092] In one implementation, the permanent magnet 21 in this embodiment includes a plurality of permanent magnet blocks, each of which is attached to the inner surface of the rotor core 20, i.e., the permanent magnet blocks are surface-mounted permanent magnet blocks.

[0093] As another implementation, the permanent magnet 21 can be an integral ring structure, fitted and fixed to the inner surface of the rotor core 20. The permanent magnet 21 can be fixed to the inner surface of the rotor core with glue.

[0094] like Figure 1 As shown, in the embodiments of this disclosure, the polar arc coefficient of the permanent magnet 21 is 1.

[0095] In the embodiments of this disclosure, the motor 100 is a three-phase motor, with the stator teeth number / 3, i.e., N / 3, having a greatest common divisor C with the number of permanent magnet poles P that can be greater than or equal to 2 and less than or equal to 8, i.e., C = GCD(N / 3, P), and 2 ≤ C ≤ 8, where GCD represents the greatest common divisor operation; the winding coils with stator teeth number / C / 3 are connected in series to form the smallest unit, and the smallest units are connected in series, parallel, or a combination of series and parallel to form any one phase of the stator winding.

[0096] For example, the ratio of the number of poles P of the permanent magnet to the number of teeth N of the stator, i.e., P / N, can be greater than or equal to 0.78 and less than or equal to 1.34.

[0097] It should be noted that the electromagnetic configuration described above in this embodiment was proposed by the inventors after considering factors such as the difficulty of process implementation and the overall electromagnetic performance of the motor. This embodiment optimizes the motor configuration, making the motor manufacturing and assembly less difficult, reducing ineffective wiring, simplifying processing, facilitating automation, reducing specific processes, reducing management costs, and enabling the motor to have a wider speed range and more universal operating conditions, without sacrificing the motor's torque density and motor constant.

[0098] In the embodiments of this disclosure, the number of stator teeth can be 48, i.e., N = 48, and the number of poles is 52, i.e., P = 52, i.e., C = GCD(16, 52) = 4, N / C / 3 = 4, P / N = 1.083. This number of tooth poles has good overall performance: low cogging torque, low operating noise, and good torque performance. In this embodiment, the resistance of the stator winding can be adjusted by changing the series and parallel connection of the winding coils in the stator winding, so as to achieve the purpose of setting different operating voltages and rated speeds, eliminating the trouble of changing the wire diameter of the motor winding coils and simplifying the manufacturing process.

[0099] For example, within a weight range of 10g to 1.5kg and a stator core diameter range of 10mm to 150mm, the motor constant per unit mass of the motor provided in this embodiment can reach [value missing]. Furthermore, it possesses realistic manufacturing and mass production feasibility, representing a significant improvement over existing technologies. Under conditions of equal or similar motor weight, the same operating voltage, and good heat dissipation, the output power of the permanent magnet brushless motor in this embodiment can be increased by more than 30%, or the weight can be reduced by more than 25% for the same power output, efficiency, or force efficiency.

[0100] Embodiments of this disclosure also provide a method for manufacturing a permanent magnet brushless motor, which is as described above, such as... Figure 12 As shown, the manufacturing method includes:

[0101] Preparation of stator core;

[0102] Prepare the stator winding coil to obtain an air coil;

[0103] The hollow coil is sleeved and fixed onto the stator core;

[0104] Make electrical connections to the winding coils.

[0105] For example, preparing the winding coil of the stator winding to obtain a hollow coil may include: using a winding machine to wind enameled wire onto a bobbin to obtain a hollow coil.

[0106] For example, making electrical connections to the winding coils may include connecting the winding coils according to the connection method specified for the motor windings.

[0107] The stator includes the stator core and the stator windings.

[0108] For example, in this manufacturing method, for each stator tooth, the winding coil 11 forms several layers of wire from the inside out, wherein the number of winding coil wire layers n is an even number. It should be noted that the number of wire layers refers to the maximum number of layers; in some areas, the number of wire layers can be less than n, for example, n-1 layers of wire. From the inside out means from the center of the stator tooth outwards. The conductor of each winding coil is a circular wire with a circular cross-section or a square wire with an approximately square cross-section. The outer diameter of the circular wire with its sheath is dc, the side length of the square wire with its sheath is dc, q is half the arc length between the tooth ends 1021 of adjacent stator teeth away from the stator yoke in the axial cross-section of the stator core, and p is half the arc length between the tooth roots 1022 of adjacent stator teeth near the stator yoke in the axial cross-section of the stator core of the stator winding.

[0109] Preparing the stator winding coil to obtain a hollow coil may further include: determining the range of the outer diameter dc of the circular wire or the range of the side length dc of the square wire, in order to select the conductor to prepare the winding coil.

[0110] For example, determining the range of the outer diameter dc of the circular wire or the range of the side length dc of the square wire to select the conductor for preparing the winding coil may include:

[0111] when When this is the case, the range of values ​​for dc is determined as follows:

[0112]

[0113] when or When this is the case, the range of values ​​for dc is determined as follows:

[0114]

[0115] in or

[0116] For example, the preparation of a stator core may include: forming the stator core, chamfering the edges of the stator core teeth, and surface treatment of the stator core.

[0117] For example, in the embodiments of this disclosure, there is no specific order in which the stator core is prepared and the winding coil of the stator winding is prepared. The winding coil can be prepared first and then the stator core, or the stator core can be prepared first and then the winding coil, or the two can be performed simultaneously. The embodiments of this disclosure do not limit this.

[0118] For example, the preparation of the stator core may include: the stator core may be formed by stamping and stacking silicon steel sheets; the chamfering of the stator core tooth edge refers to the process of processing the sharp edge of the stator core tooth into a non-sharp edge, and the non-sharp edge after chamfering may be an obtuse edge, a rounded edge, or other non-sharp edge, which is not limited in this invention; the surface treatment of the stator core refers to the process of attaching electrophoretic paint to the stator core through electrochemical means or attaching a paint film to the stator core through vapor deposition.

[0119] For example, preparing the stator winding coil to obtain an air-core coil may include: using a winding machine to wind enameled wire onto a bobbin to obtain an air-core coil. A winding machine is any device capable of converting wire into a coil.

[0120] For example, fixing the coil and the stator core may include: fitting the hollow coil onto the completed stator core; if necessary, applying adhesive to the stator core teeth or the cavity of the hollow coil before fitting, and curing the adhesive after fitting; or, in other embodiments, applying adhesive to the axial surface of the winding coil after fitting, and fixing the winding coil to the stator teeth by fixing the relative position of the winding coil to prevent it from coming loose.

[0121] For example, the electrical connection of the coil may include connecting the coil according to the connection method specified for motor windings. In one embodiment, the electrical connection of the coil is partly achieved by directly winding the coil during the coil fabrication process, and partly by soldering it to a printed circuit board; in other embodiments, the electrical connection between coils may also be achieved through methods such as overhead wiring, terminal wiring, or overhead soldering. It should be noted that the electrical connection of the coil may occur after the coil and core are fixed in sequence; it may also occur during coil fabrication; or it may occur before the coil and stator core are fixed; or it may be an organic combination of some occurring before the coil and core are fixed, some occurring during coil fabrication, and some occurring after the coil and core are fixed.

[0122] Embodiments of this disclosure also provide a multi-rotor aircraft, including a permanent magnet brushless motor as described above.

[0123] Embodiments of this disclosure also provide a robot including a permanent magnet brushless motor as described above.

[0124] This disclosure provides a permanent magnet brushless motor and its manufacturing method, a multi-axis aircraft, and a robot. The winding coil of the permanent magnet brushless motor is machine-wound and then fitted onto the stator teeth, thereby avoiding interference during coil winding and improving slot fill factor. Further, in this disclosure, based on half the arc length between the tooth ends of adjacent stator teeth away from the stator yoke in the axial cross-section of the stator core and half the arc length between the tooth roots of adjacent stator teeth near the stator yoke in the axial cross-section of the stator core, and taking into account the number of winding layers, the range of the outer diameter or side length of the conductor of the winding coil is determined, thereby significantly improving the slot fill factor and increasing the motor's torque density and motor constant per unit mass. Furthermore, the determination of the outer diameter or side length of the wire with sheath, along with the setting of other motor structural parameters and motor manufacturing process, optimizes the size and structure of the motor. While ensuring low cogging torque and smooth motor operation, it also ensures that the wound coils are consistent, compact, and safe, guaranteeing stable assembly and fit between the coils and the motor, and maximizing the use of motor slot space. This results in high slot fill factor and low DC and AC copper losses in mass-produced motors, thereby improving the torque density and motor constant per unit mass of the motor.

[0125] The following points should be noted regarding this disclosure:

[0126] (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure. Other structures can be referred to the general design.

[0127] (2) For clarity, the thickness of layers or regions in the drawings used to describe embodiments of the present disclosure is enlarged or reduced, i.e., these drawings are not drawn to actual scale.

[0128] (3) Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0129] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. The scope of protection of this disclosure shall be determined by the scope of the claims.

Claims

1. A permanent magnet brushless motor, wherein the motor is a fractional-slot external rotor motor, and the motor includes a stator and a rotor; The stator includes a stator core and a stator winding, wherein the stator winding is a non-interlaced concentrated winding with a span of 1. The rotor includes a permanent magnet and a rotor core. The permanent magnet is used to generate a rotating magnetic field. The stator core includes a stator yoke and a stator tooth section. The stator tooth section includes a plurality of stator teeth disposed on the stator yoke, and each stator tooth has an insulating layer on its surface. The stator winding includes multiple winding coils formed by machine winding, each of the multiple winding coils being symmetrically arranged on the corresponding stator tooth about the radial center axis of the corresponding stator tooth. The conductor of each winding coil is a circular wire with a circular cross-section or a rounded rectangular wire with a cross-section of approximately equal length and width, wherein the outer diameter of the circular wire with its sheath is d. c The wire with a cross-section that is a rounded rectangle with approximately equal length and width has a sheathed side length of d. c Each of the winding coils comprises multiple layers of ribbon cable from the inside out, and the number of layers of the ribbon cable is n, where n is an even number. when At that time, d c The range of values ​​for is: ； when or At that time, d c The range of values ​​for is: ； in or , q is half the arc length between the tooth ends of adjacent stator teeth away from the stator yoke in the axial cross section of the stator core, and p is half the arc length between the tooth roots of adjacent stator teeth near the stator yoke in the axial cross section of the stator core.

2. The permanent magnet brushless motor according to claim 1, wherein the input of the winding coil is located on the side near the stator yoke.

3. The permanent magnet brushless motor according to any one of claims 1-2, wherein the width of the stator teeth is the same from the tooth tip away from the stator yoke to the tooth root near the stator yoke; or The width of the stator teeth gradually increases from the tooth tip away from the stator yoke to the tooth root near the stator yoke.

4. The permanent magnet brushless motor according to claim 1, wherein the surface insulation layer of each stator tooth is an electrophoretic surface treatment layer or a vapor deposition surface treatment layer.

5. The permanent magnet brushless motor according to claim 3, wherein the edge of the stator tooth extending from the tooth root to the tooth tip has a chamfered structure.

6. The permanent magnet brushless motor according to claim 1, wherein the width of the narrowest part of the stator tooth is greater than or equal to 25% of the outer circumference of the stator's outer diameter / N, and less than or equal to 60% of the outer circumference of the stator's outer diameter / N, wherein, N is the number of stator teeth.

7. The permanent magnet brushless motor according to claim 6, wherein the width of the widest part of the stator tooth is less than or equal to 3.2 mm.

8. The permanent magnet brushless motor according to claim 6, wherein the thickness of the stator yoke is greater than or equal to 60% of the width of the narrowest part of the stator tooth, and less than or equal to 175% of the width of the narrowest part of the stator tooth.

9. The permanent magnet brushless motor according to claim 1, wherein an air gap is formed between the stator and the rotor, and the average air gap distance of the motor is less than or equal to 0.6% of the outer diameter of the stator.

10. The permanent magnet brushless motor according to claim 1, wherein the outer diameter of the stator core is less than or equal to 150 mm.

11. The permanent magnet brushless motor according to claim 10, wherein the axial height of the stator core is less than or equal to 25% of the outer diameter of the stator core.

12. The permanent magnet brushless motor according to any one of claims 1-2, wherein the average radial thickness of the permanent magnet is less than or equal to 20 times the average air gap distance and greater than or equal to 4.5 times the average air gap distance.

13. The permanent magnet brushless motor according to any one of claims 1-2, wherein the radial thickness of the rotor core is greater than or equal to 50% of the radial thickness of the permanent magnet and less than or equal to 175% of the radial thickness of the permanent magnet.

14. The permanent magnet brushless motor according to claim 1, wherein the motor is a three-phase motor, and the greatest common divisor C of the number of stator teeth / 3 and the number of permanent magnet poles is greater than or equal to 2 and less than or equal to 8.

15. The permanent magnet brushless motor according to claim 14, wherein (the number of stator teeth / C) / 3 of the winding coils are connected in series to form a minimum unit, and the minimum units are connected in series, in parallel, or in series and parallel to form any one phase of the stator winding.

16. The permanent magnet brushless motor according to claim 1, wherein the ratio of the number of poles of the permanent magnet to the number of teeth of the stator is greater than or equal to 0.78 and less than or equal to 1.

34.

17. A method for manufacturing a permanent magnet brushless motor as described in claim 1, comprising: Preparation of stator core; The preparation of the stator winding coil includes: A hollow coil is obtained by winding enameled wire onto a bobbin using a winding machine; The hollow coil is sleeved and fixed onto the stator core; Making electrical connections to the coil includes: Connect the winding coils according to the specified connection method for the motor windings.

18. A multi-rotor aircraft comprising a permanent magnet brushless motor as claimed in any one of claims 1-16.

19. A robot comprising a permanent magnet brushless motor as claimed in any one of claims 1-16.

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