Rotor of external rotor motor and motor

Abstract

The invention relates to the field of motors, and provides a rotor of an external rotor motor and a motor, and the rotor comprises a rotor iron core and a plurality of rotor magnetic poles which are arranged at the side close to the axis and are uniformly distributed in the circumferential direction. And each rotor magnetic pole comprises a plurality of magnets with different residual magnetism parameters and / or radial positions to form a mixed magnetic steel structure. The air-gap magnetic field distribution is optimized through differentiated magnet layout, so that the air-gap magnetic field is closer to a sinusoidal waveform, and harmonic distortion is reduced. According to the design, torque pulsation and electromagnetic excitation caused by uneven magnetic fields of a traditional outer rotor motor are effectively suppressed, operation noise and vibration are remarkably reduced, and the NVH performance is improved. The asymmetric magnetic pole configuration is adopted to enhance the magnetic field regulation and control capability, the smooth output of the electromagnetic torque is realized while the high power density is maintained, and the requirements of the modern industry on the high-efficiency low-noise outer rotor motor are met.

Description

Technical Field

[0001] This invention relates to the field of electric motors, and in particular to a rotor and motor of an external rotor motor. Background Technology

[0002] As a special type of motor, external rotor motors have received widespread attention and rapid development in recent years due to their advantages such as low-speed, high-torque output characteristics, good heat dissipation performance, and ease of maintenance. They are used in various application fields such as power tools, electric bicycles, wind power generation, and high-end home appliances.

[0003] However, external rotor motors commonly suffer from torque pulsation during operation. Torque pulsation originates from the non-ideal interaction of the electromagnetic fields within the motor, causing the output torque to fluctuate periodically with rotor position or time. When the frequency of this pulsation is close to the natural frequency of the motor's structure or the natural frequency of its connected load system, resonance can easily occur, leading to severe mechanical vibration and harsh high-frequency electromagnetic noise, seriously affecting the equipment's NVH (noise, vibration, and harshness) performance, operational stability, and service life. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a rotor and motor for an external rotor motor to reduce motor noise.

[0005] To achieve the above and other related objectives, the present invention provides a rotor for an external rotor motor, comprising:

[0006] Rotor core;

[0007] The rotor magnetic poles are disposed on the side of the rotor core near the rotor shaft, and multiple rotor magnetic poles are evenly spaced around the rotor shaft.

[0008] The rotor pole comprises multiple magnets, and at least two magnets in the same rotor pole have different remanent magnetization parameters and / or different distances to the rotor shaft.

[0009] In an optional embodiment of the present invention, an odd number of magnets are provided in the same rotor pole, and the magnets in the same rotor pole are arranged along a first direction.

[0010] In an optional embodiment of the present invention, an even number of magnets are provided in the same rotor pole, and the magnets in the same rotor pole are arranged along a first direction.

[0011] In an optional embodiment of the present invention, the types of magnets in the same rotor pole are arranged symmetrically about an axis of symmetry, which is the radial direction of the rotor.

[0012] In an optional embodiment of the invention, the geometric centers of adjacent magnets in the same rotor pole are staggered in a second direction.

[0013] In an optional embodiment of the present invention, the magnetic poles of the magnets are oriented toward the rotor shaft, and the magnetic poles of the magnets in the same rotor magnetic pole have the same direction.

[0014] In an optional embodiment of the present invention, the remanent magnetization parameter of the magnet closer to the axis of symmetry is greater than that of the magnet farther from the axis of symmetry.

[0015] In an optional embodiment of the present invention, the distance between the magnet closer to the axis of symmetry and the rotor axis is less than the distance between the magnet farther from the axis of symmetry and the rotor axis.

[0016] In an optional embodiment of the present invention, the magnet includes a first dimension and a second dimension, the first dimension being the dimension of the magnet in a first direction, and the second dimension being the dimension of the magnet in a second direction, wherein the second dimension of the magnet near the center in the first direction is greater than the second dimension of the magnet far from the center.

[0017] In an optional embodiment of the present invention, the first dimension of the magnet in the middle of the first direction is 1.3-1.5 times the first dimension of the magnets at both ends of the first direction.

[0018] In an optional embodiment of the present invention, the second dimension of the magnet in the middle of the first direction is 1.2-2 times the second dimension of the magnets at both ends of the first direction.

[0019] In an optional embodiment of the present invention, the magnet is fixed to the surface of the rotor core by filling the gap with adhesive, or is embedded in the groove of the rotor core by a T-shaped tenon structure.

[0020] The present invention also proposes an electric motor, comprising:

[0021] case;

[0022] The stator is disposed within the housing;

[0023] The rotor is disposed within the housing and surrounds the stator circumferentially; the rotor is the rotor of the external rotor motor.

[0024] This invention proposes a rotor and motor for an external rotor motor. By arranging multiple magnets within the same rotor pole and varying the remanent magnet parameters and / or radial positions of these magnets, the distribution of the internal magnetic field of the motor is altered. This hybrid magnet design makes the magnetic field distribution of the motor more closely resemble a sinusoidal waveform, reducing harmonic distortion of the magnetic field. In traditional external rotor motors, the uneven magnetic field distribution often generates strong torque pulsation. This innovative magnet layout effectively smooths the changes in the motor's magnetic field, achieving a significant reduction in torque pulsation, a decrease in electromagnetic excitation, and an improvement in NVH performance. This significantly enhances the overall performance of the external rotor motor, making it more suitable for the demands of modern industry for high-performance motors. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the rotor structure of an external rotor motor in the prior art;

[0027] Figure 2 This is a schematic diagram of the structure of the external rotor motor rotor in a specific embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the magnetic pole structure of the external rotor motor rotor in a specific embodiment of the present invention;

[0029] Figure 4 The diagram shows the torque pulsation waveforms of the prior art and the present invention in a specific embodiment of the present invention (where the dashed line is the torque pulsation waveform of the rotor in the prior art, and the solid line is the torque pulsation waveform of the rotor in the present invention).

[0030] Figure 5 The diagram shows the torque pulsation spectrum of the prior art and the present invention in a specific embodiment of the present invention (where the dark bars are the torque pulsation spectrum of the rotor in the prior art, and the light bars are the torque pulsation spectrum of the rotor in the present invention).

[0031] Explanation of reference numerals in the attached diagram: 10, rotor core; 20, rotor pole; 30, axis of symmetry; 40, stator; 1, first magnet; 2, second magnet; 3, third magnet; 4, fourth magnet; 5, fifth magnet. Detailed Implementation

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0033] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0034] External rotor motors exhibit excellent operational stability and durability under high torque load conditions, and their structural design facilitates heat dissipation and maintenance, leading to their increasingly widespread application in industrial fields. A key characteristic of external rotor motors is that the rotor is located on the outer side of the motor, bringing the heat dissipation path closer to the ambient air, thus improving heat dissipation efficiency. This feature enables them to demonstrate better thermal management capabilities than internal rotor motors in high-load and high-speed operating environments, making them suitable for various fields such as fans, power tools, and electric vehicles, especially excelling in scenarios requiring high power density and long-term stable operation.

[0035] However, a significant technical challenge faced by external rotor motors in application is torque ripple. Torque ripple refers to the periodic fluctuations in output torque over time caused by irregular changes in electromagnetic force during motor operation. Torque ripple not only reduces the smoothness of motor operation but also triggers a series of negative effects related to vibration and noise. When the frequency of torque ripple approaches the natural frequency of the motor or its connected mechanical system, resonance may occur, leading to strong vibrations and the generation of high-frequency noise, affecting the stable operation of the equipment and causing structural fatigue.

[0036] Especially in external rotor motors, due to their simpler structure, the rotor magnets are typically arranged within a narrow annular space, limiting the freedom of optimization design. Compared to internal rotor motors, external rotor motors have less space for rotor magnet installation, which restricts the optimization design space for the rotor magnetic field, making the torque ripple problem more prominent. Therefore, although external rotor motors have many advantages under high torque loads, technological progress in reducing torque ripple and improving NVH (noise, vibration, and harshness) performance has been relatively slow, and has not yet fully met the market demand for high-performance motors.

[0037] Currently, the industry typically reduces electromagnetic excitation and thus the impact of torque ripple by optimizing the motor's topology. Common optimization measures include improving stator and rotor magnetic circuit design, optimizing magnet layout, and adjusting winding distribution; these methods are more prevalent in internal rotor motors. However, due to the more compact structure of external rotor motors and the fact that the rotor magnets are mounted in a ring-shaped space, the optimization space is very limited. This makes it difficult for existing technologies to significantly reduce torque ripple, and the impact of torque ripple remains significant, especially under high-load, high-speed operating environments, where motor vibration and noise problems cannot be effectively resolved.

[0038] Therefore, considering the structural characteristics of external rotor motors and the limitations of existing technologies, there is an urgent need to propose an innovative topology that can effectively reduce torque ripple, decrease electromagnetic excitation, and improve the motor's NVH performance. This new structure can not only improve the motor's operational stability under high load and high speed conditions, but also reduce vibration and noise caused by torque ripple, significantly improving the motor's overall performance and meeting the industrial sector's demand for high-efficiency, low-noise motors.

[0039] To solve the above problems, such as Figure 2-5 As shown, to achieve the above-mentioned and other related objectives, this invention proposes a rotor for an external rotor motor, comprising a rotor core 10 and rotor magnetic poles 20. This patent uses a 32-pole, 96-slot external rotor motor as an example.

[0040] The rotor magnetic poles 20 are located on the side of the rotor core 10 near the rotor shaft. By shortening the effective interaction distance between the magnetic poles and the stator 40, the closed magnetic circuit path is optimized. Multiple rotor magnetic poles 20 are evenly spaced around the rotor shaft to form a symmetrical magnetic field generating unit.

[0041] The rotor pole 20 comprises multiple magnets, with at least two magnets in the same rotor pole 20 having different remanent magnetization parameters and / or radial positions. The magnets are fixed to the surface of the rotor core 10 by filling gaps with adhesive, or embedded into grooves in the rotor core 10 via a T-slot tenon structure. Adhesive filling fixation involves creating mounting positions on the surface of the rotor core 10, injecting a highly adhesive (such as epoxy resin) to fill all gaps between the magnet and the core, and curing to form an elastic support layer. T-slot tenon fixation involves machining T-shaped grooves in the rotor core 10, forming a mechanical interlock with the tenons on the side of the magnet, and strengthening the connection with lateral locking components.

[0042] By mixing magnets with different remanence parameters and radial positions, the motor's magnetic field distribution becomes more uniform and approaches a sinusoidal waveform. Traditional external rotor motors typically have complex magnetic field distributions with a certain amount of harmonics, leading to torque ripple and electromagnetic excitation. The design of this invention, using a hybrid magnet distribution, effectively reduces these harmonic distortions, decreases the amplitude of torque ripple, and thus reduces vibration and noise caused by electromagnetic excitation. Motor torque ripple is caused by periodic changes in electromagnetic force, which usually leads to irregular vibration and noise. By adjusting the magnetic parameters and positions of different magnets in the rotor poles 20, this invention makes the motor's magnetic field smoother and reduces the intensity of torque ripple. This means that under high torque loads and high-speed operation, the motor can achieve more stable output, reducing vibration and noise caused by torque fluctuations. By reducing torque ripple and electromagnetic excitation, this invention effectively reduces vibration and noise during motor operation. This is particularly important for equipment in industrial applications, as high-frequency noise and vibration not only affect the user's operating environment but can also accelerate the wear and aging of mechanical components. Therefore, this invention reduces torque pulsation by improving the rotor magnetic field of the motor, thereby significantly improving the NVH performance of the motor and making it more reliable and comfortable in industrial applications.

[0043] like Figure 2 , Figure 3 As shown, an odd number of magnets are arranged in the same rotor pole 20. This odd-numbered magnet arrangement makes the magnetic field distribution closer to a sinusoidal waveform, reducing the magnetic field inhomogeneity caused by traditional arrangements, thereby reducing torque ripple. The magnets in the same rotor pole 20 are arranged along a first direction. The first direction is perpendicular to the rotor axis and parallel to the tangent direction at the position of the rotor pole 20. This arrangement helps to optimize the magnetic field distribution of the motor, making it smoother and reducing high-frequency fluctuations in the magnetic field. The smooth change of the magnetic field directly reduces electromagnetic excitation, thereby reducing vibration and noise generated by electromagnetic forces.

[0044] like Figure 2 , Figure 3 As shown, the types of magnets in the same rotor pole 20 are arranged symmetrically about the axis of symmetry 30, which is the radial direction of the rotor. This symmetrical arrangement of magnets within the rotor pole 20, based on the rotor's radial axis of symmetry 30, helps to further balance the magnetic force distribution within the motor, avoiding any skewness or uneven changes in the magnetic field. This symmetrical arrangement makes the motor's operation more stable and further reduces the impact of torque ripple on the mechanical system.

[0045] By precisely positioning the intermediate magnet on the geometric symmetry axis 30 of the rotor magnetic pole 20, a three-level magnetic field control system is constructed, with the central magnet as the core and magnets symmetrically distributed on both sides. The intermediate magnet, as the main magnetic field source, has its magnetic circuit directly penetrating the air gap region radially, forming the basic magnetic flux path. The magnets symmetrically distributed on both sides are configured with gradient remanence parameters, forming a bidirectional compensation effect on the main magnetic field. In particular, during rotor rotation, the phase synchronization characteristics of the symmetrical magnet group can accurately match the periodic magnetic field changes of the stator slots, weakening the slot torque pulsation through the axial symmetrical cancellation effect of magnetic flux density. This layout, while retaining the manufacturing convenience of a symmetrical structure, achieves synergistic optimization of main magnetic field enhancement and harmonic suppression, making it particularly suitable for applications with stringent NVH requirements.

[0046] like Figure 2 , Figure 3 As shown, the geometric centers of adjacent magnets in the same rotor pole 20 are staggered in a second direction. This second direction is perpendicular to the first direction and the rotor axis. By rationally arranging the magnets and adjusting their remanent magnetization parameters and radial positions, the magnetic field distribution of the motor tends towards a sinusoidal waveform, thereby reducing the amplitude of torque ripple. This design avoids the strong harmonics commonly found in traditional motors and improves the output smoothness of the motor. Specifically, the magnets are distributed in a symmetrical gradient.

[0047] The symmetrical gradient distribution proposed in this invention refers to the gradient change of physical or electromagnetic parameters formed by multiple magnets (odd or even number) arranged radially (in the first direction) within a single rotor magnetic pole, centered on a predetermined axis of symmetry 30. It includes two modes:

[0048] Remanence gradient distribution: The remanence parameters (such as magnetic induction intensity) of magnets closer to the axis of symmetry 30 are significantly greater than those of magnets farther away from the axis of symmetry 30 (for example, the remanence of the central magnet is 30-50% higher than that of the edge magnets);

[0049] Radial position gradient distribution: The magnets closer to the axis of symmetry 30 are less distant from the rotor axis than the magnets farther away from the axis of symmetry 30 (for example, the position of the central magnet is 15-25% closer to the axis than that of the edge magnets).

[0050] At the electromagnetic level, the remanent magnetization gradient makes the magnetic field waveform approach an ideal sinusoidal distribution, significantly reducing torque ripple during motor operation. At the manufacturing level, the odd-numbered magnet layout uses the central magnet as the axis of symmetry 30, enhancing assembly stability; the even-numbered magnet layout relies on a virtual symmetry center line, achieving equivalent gradient symmetry through parameter matching of paired magnets, greatly reducing the need for high-precision magnet customization.

[0051] In the symmetrical gradient distribution embodiment of this invention, a mirror-symmetrical magnet parameter gradient system is constructed along the magnetic pole symmetry axis 30, achieving bidirectional optimization of magnetic field strength and waveform curvature. In this layout, the magnet exhibits a gradual change in remanent magnetization parameters or geometric position towards both sides of the symmetry axis 30, forming a bell-shaped magnetic field distribution with the axis as the peak and gradient decay on both sides. This symmetrical gradient structure maintains the dynamic balance advantage brought by the overall geometric symmetry of the magnetic poles and compensates for the magnetic permeability fluctuations at the stator slot edges through axial gradient changes in magnetic field strength. When the rotor rotates, the symmetrical gradient magnetic field and stator tooth harmonics form a dynamic cancellation mechanism with phase interleaving, eliminating even harmonics while suppressing odd harmonic amplitudes using gradient decay characteristics. This design, while ensuring the symmetry of the production process, achieves full-domain smoothing of the air gap magnetic flux density waveform through radial modulation of the magnetic field strength, providing an innovative magnetic circuit topology scheme for high-precision control and low-vibration operation of external rotor motors.

[0052] In an optional embodiment of the present invention, the magnetic poles of the magnets face the rotor shaft, and the magnetic poles of the magnets within the same rotor magnetic pole 20 have the same direction. Multiple rotor magnetic poles 20 in the annular rotor are arranged with alternating magnetic pole directions. In the magnetic pole orientation optimization embodiment of the present invention, an alternating magnetic polarity layout technique is employed. By alternately arranging magnets with different magnetic pole directions (N / S poles facing the shaft) within the annular rotor, a unique annular closed magnetic circuit system is constructed. When the N / S poles of the magnets alternately point towards the shaft, magnetic field lines form an axial-radial composite conduction path between adjacent magnets, forcing the magnetic field to form a vortex-like distribution along a predetermined direction. This directional magnetic field topology effectively suppresses the transverse harmonic components in the traditional radial magnetic field distribution, making the air gap magnetic flux density waveform exhibit quasi-sinusoidal symmetry characteristics. This design, while ensuring the compactness of the magnetic pole structure, achieves efficient directional conduction of magnetic field energy, providing a breakthrough solution for high torque density and low electromagnetic noise operation of external rotor motors.

[0053] like Figure 3As shown, the magnet includes a first dimension and a second dimension. The first dimension is the size of the magnet in the first direction, and the second dimension is the size of the magnet in the second direction. The second dimension of the magnet near the center in the first direction is larger than that of the magnet farther from the center. By constructing a symmetrical gradient distribution of the radial dimensions (second direction) of the magnet along the tangent direction of the magnetic poles (first direction), a centrally reinforced composite magnetic circuit structure is formed. The magnet located in the center of the magnetic poles strengthens the main magnetic field strength by increasing its radial dimension, constructing a high magnetomotive force core region; the gradually decreasing radial dimensions of the magnets on both sides form a transition zone of gradually decreasing magnetic reluctance, guiding the natural diffusion of magnetic field lines. This gradient size distribution makes the magnetic field energy present a smooth, bell-shaped curve in the tangential direction, effectively suppressing harmonic distortion caused by sudden changes in the magnetic field. When the rotor rotates, the gradient magnetic reluctance distribution dynamically matches the stator slots, maintaining torque output stability through the strong magnetic field in the center, while using the edge gradient region to buffer torque pulsation caused by magnetic permeability fluctuations. This design achieves precise control of magnetic field strength and distribution within a limited space, providing an innovative magnetic circuit topology solution for the efficient and low-noise operation of external rotor motors.

[0054] The first dimension of the magnet in the middle of the first direction is 1.3-1.5 times the first dimension of the magnets at both ends of the first direction. The second dimension of the magnet in the middle of the first direction is 1.2-2 times the second dimension of the magnets at both ends of the first direction.

[0055] Specifically: such as Figure 3As shown, five magnets are arranged in the same rotor pole 20. The five magnets are arranged in the following order along the first direction: first magnet 1, second magnet 2, third magnet 3, fourth magnet 4, and fifth magnet 5. First magnet 1 and fifth magnet 5 are identical and have a first dimension of 3-4 mm. The second dimension of first magnet 1 and fifth magnet 5 is 1-2 mm. The rotor pole 20 adopts a five-magnet symmetrical gradient layout design, with five magnets arranged sequentially along the tangential direction of the pole (first direction). Among them, first magnet 1 and fifth magnet 5 have the same size, but their tangential dimension (first dimension) is smaller and their radial dimension (second dimension) is even smaller, forming a compact magnet arrangement structure at both ends. This layout constructs a "center-strengthened - edge-weakened" magnetic field distribution pattern inside the pole through the size gradient difference between the middle magnet and the edge magnet. The magnet in the middle region enhances the main magnetic flux density through a larger radial dimension, while the small size design of the magnets at both ends is used to suppress the distortion and diffusion of the edge magnetic field. The symmetrical miniaturized magnets at both ends of the magnetic poles form a magnetic field buffer zone. Through the gradual change in reluctance, the magnetic field lines converge naturally, effectively eliminating lateral leakage flux and local magnetic saturation caused by traditional single large-size magnets. When the rotor rotates, this gradient layout causes the air gap magnetic flux density waveform to exhibit a smooth, convex characteristic in the circumferential direction, significantly reducing higher harmonic components. Simultaneously, the low magnetomotive force of the magnets at both ends absorbs the magnetic permeability fluctuation energy caused by the stator slots, achieving multi-frequency suppression of torque pulsation. This design achieves precise control of magnetic field strength and shape within a limited space, providing an innovative magnetic circuit optimization scheme for the efficient and low-noise operation of external rotor motors.

[0056] In an optional embodiment of the present invention, the second magnet 2 and the fourth magnet 4 are identical, with a first dimension of 4-6 mm and a second dimension of 2-3 mm. In the symmetrical arrangement of the five magnets, the second and fourth magnets 4 serve as intermediate transition units, with their increased tangential dimension (first dimension) and moderate radial dimension (second dimension) forming a progressive magnetomotive force conduction band. The two magnets are symmetrically distributed on both sides of the central magnet, enhancing the magnetic field coupling strength between adjacent magnets through a moderately expanded tangential coverage area, while the moderate radial dimension design forms a magnetoresistive buffer layer. This structure allows the magnetic field energy to exhibit a smooth secondary decay curve as it transitions from the central high magnetic density region to the edge, maintaining the continuity of the main magnetic flux path and suppressing abrupt changes in the edge magnetic field through the magnetoresistive gradient effect. During rotor rotation, the moderate magnetomotive force characteristics of the second and fourth magnets 4 can dynamically neutralize the magnetic permeability step changes caused by the stator slots, achieving smooth global control of the electromagnetic torque waveform.

[0057] In an optional embodiment of the present invention, the first dimension of the third magnet 3 is 4-6 mm, and the second dimension of the third magnet 3 is 3-4 mm. In the five-magnet symmetrical layout embodiment of the present invention, the third magnet 3, as the core unit of the magnetic pole, has its increased tangential dimension (first dimension) and significantly improved radial dimension (second dimension) jointly constructing a high-intensity magnetic field focusing region. The enlarged design of the middle magnet makes it the core carrier of the main magnetic flux, and the magnetomotive force output capability is enhanced by increasing the magnetomotive force cross-sectional area, forming a Gaussian magnetic field distribution with the center of the magnetic pole as the peak. The larger radial dimension design shortens the effective path of magnetic field lines penetrating the air gap, significantly improving the magnetic field energy transfer efficiency, while the magnetic coupling strength with adjacent magnets is enhanced by expanding the magnet width. During dynamic operation, the strong magnetic field core region formed by the third magnet 3 can stably maintain the main magnetic flux density, while its smoothly transitioning geometric edges effectively suppress harmonic distortion caused by abrupt changes in the magnetic field on both sides. This design achieves full-range smooth control of the air gap magnetic flux density waveform through the synergistic effect of the magnetic field focusing effect of the core magnet and the buffer attenuation characteristics of the edge magnet, providing core support for the high torque output and low noise operation of the external rotor motor.

[0058] Compared to the hybrid magnet structure of a 32-pole, 96-slot external rotor motor (such as...), Figure 2 , Figure 3 (as shown) and the traditional single-line magnet rotor structure (such as) Figure 1 As shown in the figure, simulation verification under the same working conditions confirms the torque ripple suppression effect of the innovative design. Figure 4 As shown, the torque pulsation waveform amplitude of the hybrid magnet rotor is significantly reduced, and the peak-to-valley fluctuation range is reduced by nearly 60% compared to the traditional structure. (Spectrum analysis) Figure 5 The results show that the amplitude of the main harmonic component (corresponding to the fundamental frequency order of the pole-slot combination) decreased by nearly 60%, and the amplitude of the high-frequency harmonic components did not increase. Especially under peak load conditions, the hybrid magnet rotor effectively suppresses the core excitation source of torque pulsation through the gradient magnetic field distribution and harmonic phase cancellation effect. This design achieves synchronous attenuation of the main harmonic and wide-frequency harmonic energy while ensuring torque output capability, verifying the control advantages of the asymmetric magnetic circuit topology on the electromagnetic excitation source, and providing an effective solution for the precision control and low-noise operation of external rotor motors.

[0059] The present invention also proposes an electric motor, including a housing, a stator 40, and a rotor. As the basic support and protection unit of the electric motor, the housing is manufactured using a split casting process to form a composite structure including axial ventilation channels and heat dissipation fins.

[0060] The stator 40 is housed within the housing. The stator 40 adopts a multi-slot distributed winding layout, and its tooth end face is optimized by curved surface to form a harmonic suppression slot, which forms complementary magnetic permeability characteristics with the rotor magnetic pole 20.

[0061] The rotor is housed within the casing and surrounds the stator 40 circumferentially. This rotor is the same as the aforementioned external rotor motor. The core innovation of the rotor lies in its modular magnetic pole design. Each magnetic pole incorporates a gradient arrangement of magnets to form a main magnetic field enhancement zone and an edge harmonic attenuation zone. The magnet dimensions are symmetrically and gradually distributed along the tangential direction. The central magnet enhances magnetic flux density, while the magnets on both sides guide a smooth transition of the magnetic field through size contraction. The asymmetrical pole-slot matching between the rotor and stator 40, along with the magnetic field phase compensation mechanism, enables full-domain sinusoidal control of the air gap magnetic flux density waveform. This structural system, while ensuring power density, achieves multiple technical effects—electromagnetic excitation source suppression, thermal distribution equalization, and vibration and noise control—through magnetic circuit topology optimization and mechanical dynamic balance design.

[0062] In summary, this invention achieves a synergistic enhancement of multiple technical effects through the gradient magnet layout and topology optimization design of the rotor poles 20. By constructing an asymmetric magnetic circuit system using magnets with different remanence parameters and radial positions, the air gap magnetic field distribution approaches an ideal sinusoidal waveform, effectively suppressing low-order spatial harmonics and reducing magnetic field distortion rate. The innovative combination of odd-numbered magnet arrangement, symmetrical gradient size distribution, and alternating polarity orientation eliminates the inherent even-order harmonic superposition effect of traditional symmetrical structures. The cogging torque pulsation is weakened through magnetic field phase compensation and magnetic reluctance gradient mechanisms. The gradient magnetic field distribution mode, with center reinforcement and edge attenuation within the poles, absorbs the magnetic permeability fluctuation energy caused by stator slots while maintaining the main magnetic flux density, significantly reducing vibration and noise caused by electromagnetic excitation. Combined with pole-slot matching optimization and dynamic magnetic field modulation technology, smooth control of the entire electromagnetic torque output is achieved. This design system, while increasing power density, achieves a comprehensive improvement in high-precision magnetic field control, wide-frequency noise suppression, and operational stability through the synergistic effect of magnetic circuit reconstruction and mechanical dynamic balance, providing core assurance for the efficient and low-noise operation of external rotor motors under complex working conditions.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention. This invention efficiently achieves high-voltage connection between the motor and the controller, is compact, features an oil-resistant sealing design to ensure reliable sealing between the controller cavity and the motor cavity, and incorporates an oil-cooling design for the external rotor motor's rotor and motor, effectively reducing temperature, achieving greater current flow, and extending product lifespan.

[0064] Throughout this description, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of embodiments of the invention. However, those skilled in the art will recognize that embodiments of the invention may be practiced without one or more of these specific details or by other devices, systems, components, methods, parts, materials, components, etc. In other instances, well-known structures, materials, or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention.

[0065] Throughout this specification, the terms "an embodiment," "embodiment," or "specific embodiment" refer to a particular feature, structure, or characteristic described in connection with an embodiment that is included in at least one embodiment of the invention, but not necessarily in all embodiments. Therefore, the various representations of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout the specification do not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic of any specific embodiment of the invention can be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein may be based on the teachings herein and will be considered part of the spirit and scope of the invention.

[0066] It should also be understood that one or more of the elements shown in the figures may be implemented in a more separate or more integrated manner, or may even be removed because they are inoperable in certain circumstances or provided because they may be useful for a particular application.

[0067] Furthermore, unless otherwise expressly stated, any arrows in the accompanying drawings should be considered illustrative only and not limiting. Additionally, unless otherwise stated, the term "or" as used herein is generally intended to mean "and / or". Where a term is anticipated to provide a separation or combination capability that is unclear, a combination of components or steps will also be considered as indicated.

[0068] As used herein and throughout the claims below, unless otherwise specified, “a” and “the” include the plural references. Similarly, as used herein and throughout the claims below, unless otherwise specified, “in” means “in” and “on”.

[0069] The above description of the embodiments shown in this invention (including the content set forth in the abstract of the specification) is not intended to be an exhaustive enumeration or to limit the invention to the precise forms disclosed herein. Although specific embodiments and examples of the invention have been described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the invention, as will be recognized and understood by those skilled in the art. As indicated, these modifications can be made to the invention in accordance with the above description of the embodiments described herein, and such modifications will be within the spirit and scope of the invention.

[0070] This document has generally described the systems and methods in detail to aid in understanding the invention. Furthermore, various specific details have been set forth to provide a general understanding of embodiments of the invention. However, those skilled in the art will recognize that embodiments of the invention can be practiced without one or more specific details, or using other means, systems, accessories, methods, components, materials, parts, etc. In other instances, well-known structures, materials, and / or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention.

[0071] Therefore, although the invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are also within the scope of the foregoing disclosure, and it should be understood that in some cases, certain features of the invention may be adopted without departing from the scope and spirit of the invention and without corresponding use of other features. Thus, many modifications can be made to adapt a particular environment or material to the essential scope and spirit of the invention. The invention is not intended to be limited to the specific terminology used in the following claims and / or the specific embodiments disclosed as the best mode for carrying out the invention, but the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Therefore, the scope of the invention will be defined only by the appended claims.

Claims

1. A rotor for an external rotor motor, characterized in that, include: Rotor core; The rotor magnetic poles are disposed on the side of the rotor core near the rotor shaft, and multiple rotor magnetic poles are evenly spaced around the rotor shaft. The rotor pole comprises multiple magnets, and at least two magnets in the same rotor pole have different remanent magnetization parameters and / or different distances to the rotor shaft.

2. The rotor of the external rotor motor according to claim 1, characterized in that, An odd number of magnets are provided in the same rotor pole, and the magnets in the same rotor pole are arranged along a first direction.

3. The rotor of the external rotor motor according to claim 2, characterized in that, An even number of magnets are provided in the same rotor pole, and the magnets in the same rotor pole are arranged along a first direction.

4. The rotor of the external rotor motor according to claim 2 or 3, characterized in that, The types of magnets in the same rotor pole are arranged symmetrically about an axis of symmetry, which is the radial direction of the rotor.

5. The rotor of the external rotor motor according to claim 1, characterized in that, The geometric centers of adjacent magnets in the same rotor pole are staggered in the second direction.

6. The rotor of the external rotor motor according to claim 1, characterized in that, The magnetic poles of the magnets are oriented toward the rotor shaft, and the magnetic poles of the magnets in the same rotor magnetic pole have the same direction.

7. The rotor of the external rotor motor according to claim 4, characterized in that, The remanent magnetism of the magnet closer to the axis of symmetry is greater than that of the magnet farther from the axis of symmetry.

8. The rotor of the external rotor motor according to claim 4, characterized in that, The distance between the magnet closer to the axis of symmetry and the rotor axis is less than the distance between the magnet farther from the axis of symmetry and the rotor axis.

9. The rotor of the external rotor motor according to claim 1, characterized in that, The magnet includes a first dimension and a second dimension, the first dimension being the dimension of the magnet in a first direction, and the second dimension being the dimension of the magnet in a second direction, wherein the second dimension of the magnet near the center in the first direction is larger than the second dimension of the magnet far from the center.

10. The rotor of the external rotor motor according to claim 9, characterized in that, The first dimension of the magnet in the middle of the first direction is 1.3-1.5 times the first dimension of the magnets at both ends of the first direction.

11. The rotor of the external rotor motor according to claim 9, characterized in that, The second dimension of the magnet in the middle of the first direction is 1.2 to 2 times the second dimension of the magnets at both ends of the first direction.

12. The rotor of the external rotor motor according to claim 1, characterized in that, The magnet is fixed to the surface of the rotor core by filling the gaps with adhesive, or it is embedded in the groove of the rotor core by a T-shaped tenon structure.

13. An electric motor, characterized in that, include: case; The stator is disposed within the housing; The rotor is disposed within the housing and surrounds the stator circumferentially, and the rotor is the rotor of an external rotor motor as described in any one of claims 1-12.

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