Rotor and electric machine

Abstract

This application belongs to the field of motor technology, specifically relating to a rotor and a motor. The rotor includes: a rotor core; a plurality of first permanent magnets, embedded circumferentially within the rotor core, the first permanent magnets extending radially along the rotor core, with adjacent first permanent magnets having opposite magnetization directions; and a plurality of sets of second permanent magnets, embedded within the rotor core, each set of second permanent magnets positioned between adjacent first permanent magnets, with the first permanent magnets and a set of second permanent magnets alternating circumferentially along the rotor core at a ratio of 1:n, where n≥3. The second permanent magnets are positioned close to the central axis of the rotor core, and the magnetization direction of each set of second permanent magnets is either away from or close to the central axis of the rotor core, with adjacent sets of second permanent magnets having opposite magnetization directions. This application can effectively reduce end leakage flux and rotor center hole leakage flux problems, improve the utilization rate of permanent magnets, and achieve a significant increase in average torque.

Description

Technical Field

[0001] This application relates to the field of motor technology, and more specifically, to a rotor and a motor. Background Technology

[0002] Permanent magnet motors, with their superior performance such as high torque density and high efficiency, are widely used in aerospace, electric vehicles, and industrial automation. Among them, the spoke-type built-in permanent magnet motor, with its unique permanent magnet arrangement, can improve the air gap magnetic flux density and exhibits a significant advantage in output torque.

[0003] However, traditional spoke-type rotor structures have inherent defects, mainly manifested in significant magnetic leakage: First, magnetic leakage is prominent at the magnet ends. The asymmetry of the magnetic circuit topology of the permanent magnets, embedded in the rotor in a spoke-like shape, leads to a localized increase in magnetic field strength at the magnet ends, causing severe magnetic leakage. Second, magnetic leakage occurs in the rotor's central hole. Existing structures cannot effectively confine the magnetic field to diffuse towards the rotor's central region, resulting in central hole leakage and further weakening the effective magnetic flux density in the air gap. Furthermore, magnetic leakage not only interferes with the operation of surrounding equipment but also reduces the motor's energy conversion efficiency and increases energy consumption. Simultaneously, magnetic leakage can induce electromagnetic force imbalance within the rotor, accelerating component wear and shortening the motor's lifespan.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a rotor and motor that can effectively reduce end leakage flux and rotor center hole leakage flux problems, improve the utilization rate of permanent magnets, and achieve a significant increase in average torque.

[0006] In a first aspect, this application provides a rotor, comprising: a rotor core having a plurality of first mounting slots and a plurality of sets of second mounting slots, the plurality of first mounting slots being spaced apart circumferentially along the rotor core and extending radially along the rotor core; each set of second mounting slots being disposed between two adjacent first mounting slots and being disposed close to the central axis of the rotor core, the first mounting slots and a set of second mounting slots being alternately placed circumferentially along the rotor core at a ratio of 1:n, where n≥3; a plurality of first permanent magnets embedded in the first mounting slots, the magnetization direction of the first permanent magnets being set at a preset angle to the radial direction of the rotor core, and the magnetization directions of two adjacent first permanent magnets being opposite; and a plurality of sets of second permanent magnets embedded in the second mounting slots, the magnetization direction of each set of second permanent magnets being either away from or close to the central axis of the rotor core, and the magnetization directions of two adjacent sets of second permanent magnets being opposite.

[0007] In one possible implementation, the first permanent magnet is elongated, and a gap is formed between the first mounting groove and the first permanent magnet.

[0008] In one possible implementation, the second permanent magnet is elongated or arc-shaped, and the second mounting groove is matched with the second permanent magnet.

[0009] In one possible implementation, a local coordinate system is established with the center of the width direction along the circumference of any first permanent magnet or second permanent magnet as the origin, the length direction along the radial direction of the rotor core as the Y-axis, and the direction perpendicular to the radial direction as the X-axis. Along the circumference of the rotor core, the angles between the magnetization directions of two adjacent first permanent magnets and two sets of second permanent magnets and the X-axis of their own local coordinate system are 0°, 360°*i / 2(n+1), i=1, 2, ..., n, 180° and 360°*k / 2(n+1), k=2n+1, 2n, ..., n+2, respectively.

[0010] In one possible implementation, when n is an even number, the dimensions of the multiple sets of second permanent magnets are all the same.

[0011] In one possible implementation, when n is an odd number, each group of second permanent magnets includes a first auxiliary permanent magnet and a second auxiliary permanent magnet. The second auxiliary permanent magnets are symmetrically arranged on both sides of the first auxiliary permanent magnets along the circumference of the rotor core, and the size of the first auxiliary permanent magnets is different from that of the second auxiliary permanent magnets.

[0012] In one possible implementation, the first auxiliary permanent magnet has a circumferential width of w1 and a radial thickness of h1 along the rotor core, and the second auxiliary permanent magnet has a circumferential width of w2 and a radial thickness of h2 along the rotor core, satisfying the following conditions: w2=(0.5~0.6)*w1, h2=(0.7~0.85)*h1.

[0013] In one possible implementation, the rotor core includes a plurality of silicon steel sheets stacked along its own axial direction. Each silicon steel sheet is provided with a first mounting hole and a second mounting hole. The first mounting holes of the plurality of silicon steel sheets are stacked to form a first mounting groove, and the second mounting holes of the plurality of silicon steel sheets are stacked to form a second mounting groove.

[0014] Secondly, this application provides an electric motor, including: the rotor of this application; and a stator, coaxially disposed with the rotor, the stator including a stator core and an armature winding embedded in the stator core, and an air gap being formed between the stator core and the rotor.

[0015] In one possible implementation, the stator is disposed on the outer periphery of the rotor; or, the rotor is disposed on the outer periphery of the stator.

[0016] According to the rotor and motor provided in this application, by adding multiple sets of second permanent magnets with specific magnetization directions inside the multiple radially extending first permanent magnet bodies of a conventional spoke rotor, the magnetization direction of the first permanent magnets is at a preset angle to the radial direction of the rotor core, and its magnetic flux contains a certain axial component. The first permanent magnets, as the main magnetic poles, can effectively suppress end leakage magnetic problems. The second permanent magnets, as auxiliary magnetic field regulators, have opposite magnetization directions between adjacent sets of second permanent magnets, so that at the shaft hole where the central axis of the rotor core is located, the magnetic fields generated by the second permanent magnets cancel each other out or form a local closed loop, forcing the magnetic flux outward to the air gap to participate in electromechanical energy conversion. This effectively suppresses magnetic leakage in the rotor's central shaft hole; the edge gradient of the air gap magnetic field is adjusted by moving the magnetization direction of the second permanent magnet away from / closer to the shaft center, achieving a magnetic focusing / splitting effect; the first and second permanent magnets are arranged alternately in the circumferential direction at a ratio of 1:n (n≥3), providing high freedom for electromagnetic design, increasing the harmonic order of the air gap magnetic flux density, enhancing the fundamental amplitude, and significantly weakening higher harmonics, thereby improving the utilization rate of the permanent magnets and facilitating the balance between high-speed magnetic field weakening and low-speed high torque; thus, multiple technical effects are achieved simultaneously, including suppressing end and center magnetic leakage, and significantly improving the average torque, combining excellent electromagnetic performance with industrial production feasibility. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the motor provided in an embodiment of this application; Figure 2 This is a schematic diagram of the rotor structure provided in an embodiment of this application; Figure 3 for Figure 2 A schematic diagram showing the magnetization direction distribution of each permanent magnet in the rotor; Figure 4 for Figure 3 A magnified view of region A in the image; Figure 5 A comparison chart of motor torque performance for four different permanent magnet configuration schemes provided in the embodiments of this application; Figure 6 for Figure 5 Enlarged view of the dashed box area; Figure 7 Fourier decomposition comparison diagram of the air gap magnetic flux density of motors with two different permanent magnet configuration schemes provided in the embodiments of this application.

[0019] Main reference numerals 100. Electric motor; 1. Rotor; 10. Rotor core; 101. First mounting slot; 102. Second mounting slot; 11. First permanent magnet; 12. Second permanent magnet; 121. First auxiliary permanent magnet; 122. Second auxiliary permanent magnet; 2. Stator; 21. Stator core; 22. Armature winding. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0021] Figure 1 This is a schematic diagram of the structure of the motor provided in an embodiment of this application.

[0022] See Figure 1 This application provides an electric motor 100, which includes a rotor 1 and a stator 2.

[0023] The stator 2 is coaxially arranged with the rotor 1. The stator 2 includes a stator core 21 and an armature winding 22 embedded in the stator core 21. An air gap is formed between the stator core 21 and the rotor 1.

[0024] Motor 100 can be a permanent magnet motor, or more specifically, a permanent magnet synchronous motor. Permanent magnet motors have high power density, high efficiency, high torque, low vibration and noise, and excellent speed regulation performance, and can be widely used in electric vehicles, high-end industrial drives, and other fields.

[0025] In some embodiments, the stator 2 is disposed on the outer periphery of the rotor 1, that is, the motor 100 has an inner rotor and outer stator structure, and an air gap is formed between the inner peripheral surface of the stator core 21 and the outer peripheral surface of the rotor 1. This air gap can be an annular air gap. In some embodiments, the rotor 1 is disposed on the outer periphery of the stator 2, that is, the motor 100 has an inner stator and outer rotor structure, and an air gap is formed between the inner peripheral surface of the rotor 1 and the outer peripheral surface of the stator core 21. This air gap can be an annular air gap. For ease of description, the embodiments of this application are used as... Figure 1 The permanent magnet motor 100 with an inner rotor and outer stator structure shown is used as an example for explanation.

[0026] The most commonly used rotor in permanent magnet motors is the spoked rotor. It utilizes the "magnetic focusing effect" generated by the tangential placement of permanent magnets to produce extremely high air gap magnetic flux density within a small volume, thus achieving excellent torque density. However, the traditional spoked rotor structure has inherent defects, primarily manifested in significant magnetic leakage. Firstly, magnetic leakage is prominent at the magnet ends. The asymmetry of the magnetic circuit topology caused by the spoked embedding of permanent magnets into the rotor leads to localized increases in magnetic field strength at the magnet ends, resulting in severe magnetic leakage. Secondly, magnetic leakage occurs in the rotor's central hole. Existing structures struggle to effectively confine the magnetic field diffusion towards the rotor's central region, causing leakage in the central hole and further weakening the effective air gap magnetic flux density. Furthermore, magnetic leakage not only interferes with the operation of surrounding equipment but also reduces the motor's energy conversion efficiency, increasing energy consumption. Simultaneously, magnetic leakage can induce electromagnetic force imbalance within the rotor, accelerating component wear and shortening the motor's lifespan.

[0027] Therefore, this application provides a rotor 1 that can effectively reduce end leakage flux and rotor center hole leakage flux problems, improve the utilization rate of permanent magnets, and achieve a significant increase in average torque.

[0028] Figure 2 This is a schematic diagram of the rotor provided in one embodiment of this application.

[0029] See Figure 2 This application provides a rotor 1, including: a rotor core 10, a plurality of first permanent magnets 11 and a plurality of sets of second permanent magnets 12.

[0030] The rotor core 10 is provided with a plurality of first mounting slots 101 and a plurality of sets of second mounting slots 102. The plurality of first mounting slots 101 are arranged at intervals along the circumference of the rotor core 10 and extend radially along the rotor core 10. Each set of second mounting slots 102 is arranged between two adjacent first mounting slots 101 and is located close to the central axis of the rotor core 10. The first mounting slots 101 and a set of second mounting slots 102 are alternately placed along the circumference of the rotor core 10 in a ratio of 1:n, where n≥3.

[0031] The first permanent magnet 11 is embedded in the first mounting groove 101. The magnetization direction of the first permanent magnet 11 is set at a preset angle with the radial direction of the rotor core 10. The magnetization directions of two adjacent first permanent magnets 11 are opposite.

[0032] The second permanent magnet 12 is embedded in the second mounting groove 102. The magnetization direction of each group of second permanent magnets 12 is away from or close to the central axis of the rotor core 10, and the magnetization directions of two adjacent groups of second permanent magnets 12 are opposite.

[0033] like Figure 2As shown, rotor 1 is a spoked rotor. The iron core portion connecting the tops of two adjacent first mounting slots 101 to the outer circumferential surface of rotor 1 is called a magnetic bridge. The magnetic bridge should be designed to be as narrow as possible, provided that mechanical strength allows. Figure 2 As indicated by the arrows, the magnetization direction of the first permanent magnet 11 is set at a preset angle to the radial direction of the rotor core 10. The magnetization directions of two adjacent first permanent magnets 11 are opposite, so that the N poles and S poles of multiple first permanent magnets 11 are alternately arranged along the circumferential direction of the outer peripheral surface of the rotor core 10 (NSNS...), forming a multi-pole pair rotor magnetic field. The first permanent magnet 11 serves as the main magnetic pole of the rotor 1, generating the basic air gap magnetic field required for the operation of the motor 100.

[0034] Each group of second permanent magnets 12 is disposed between two adjacent first permanent magnets 11, and each group of second permanent magnets 12 includes at least three second permanent magnets 12. The magnetization directions of two adjacent groups of second permanent magnets 12 are opposite. For example, if the magnetization direction of a certain group of second permanent magnets 12 is far away from the central axis of the rotor core 10, then the magnetization direction of the other group of second permanent magnets 12 adjacent to it is close to the central axis of the rotor core 10. Multiple groups of second permanent magnets 12 are arranged in a specific spatial arrangement as "magnetic field modulators": one first permanent magnet 11 corresponds to n second permanent magnets 12 to generate a set of spatial harmonic magnetic fields.

[0035] End leakage flux refers to the path by which magnetic flux bypasses the air gap and directly "short-circuits" from the axial end face of the rotor core 10 or flows back through the air. The first permanent magnet 11 is embedded in the first mounting groove 101, such that both axial ends of the first permanent magnet 11 are directly aligned with the axial end face of the rotor core 10. The first permanent magnet 11 occupies the main radial space around the rotor 1, and adjacent first permanent magnets 11 are separated by the rotor core 10 or the area of ​​the second permanent magnet 12 to be installed. Because the magnetization direction of the first permanent magnet 11 is at a predetermined angle to the radial direction of the rotor core 10, its magnetic flux contains a certain axial component. However, the axial magnetic reluctance of the rotor core 10 is much higher than its radial magnetic reluctance, making it difficult for the magnetic flux to propagate along the axial direction of the rotor core 10. Under these conditions, for magnetic flux to form end leakage, it must pass through the air gap via the end face of the first permanent magnet 11 into the stator end cavity or housing, and then return to the rotor 1. This path contains a large amount of air / non-magnetic medium, and the magnetic resistance is significantly higher than that of the main magnetic circuit that passes radially through the air gap into the stator via the rotor core 10. Therefore, driven by the principle of "minimum magnetic resistance" in the magnetic circuit, most of the magnetic flux chooses to pass radially through the air gap into the stator core, rather than through end leakage, thus effectively suppressing end leakage.

[0036] Rotor center hole leakage refers to the ineffective magnetic flux generated by the permanent magnets flowing back through the shaft hole where the rotor's central axis is located, instead of entering the stator outwards. The second permanent magnet 12 is positioned close to the central axis of the rotor core 10, and its magnetization direction is towards or away from the central axis. Assuming that the magnetization direction of one group of second permanent magnets 12 is towards the center (S pole facing inwards), while the magnetization direction of the adjacent group of second permanent magnets 12 is away from the center (N pole facing inwards), these two groups of second permanent magnets 12 form a locally closed magnetic circuit in the central region of the rotor core 10 (near the shaft hole). The magnetic flux attempting to leak into the central shaft hole from the first permanent magnet 11 encounters the opposite magnetic field generated by the second permanent magnet 12. Ideally, the magnetic flux generated by the second permanent magnet 12 precisely cancels out the leakage flux tendency of the first permanent magnet 11 in the central region, resulting in a significant reduction in the net magnetic flux through the central shaft hole. Most of the magnetic flux is forced outwards into the air gap to participate in energy conversion, thus suppressing the rotor center hole leakage problem.

[0037] In other words, the rotor 1 in this embodiment uses the first permanent magnet 11 to dominate the magnetic circuit, making the magnetic reluctance of the axial end face relatively high and suppressing end leakage magnetic flux; and uses the array of second permanent magnets 12 near the shaft center as a magnetic field modulator to confine the internal magnetic flux in a local small loop and prevent it from flowing to the rotor center hole, thereby significantly reducing the leakage magnetic flux of the rotor center hole and improving the utilization rate of permanent magnets and motor efficiency.

[0038] Furthermore, the fundamental magnetic field (useful torque component) generated by the first permanent magnet 11 radiates outwards, passing through the air gap and entering the stator. The specific subharmonic magnetic field (usually higher harmonics) generated by the second permanent magnet 12 encounters the fundamental magnetic field inside the rotor 1. Through a carefully designed 1:n (n≥3) ratio and alternating opposite magnetization directions, these two magnetic fields are vector-superimposed in space. This allows the harmonic magnetic field generated by the second permanent magnet 12 to precisely cancel or weaken the higher harmonics in the magnetic field of the first permanent magnet 11, while simultaneously enhancing the fundamental magnetic field. The second permanent magnet 12 and the rotor core 10 work together to encourage magnetic lines of force to pass more readily from the first permanent magnet 11 (main magnetic pole) and be "squeezed" towards the air gap, generating a magnetic focusing effect and increasing the air gap magnetic flux density. Simultaneously, this magnetic circuit design significantly increases the reluctance difference (salientity) between the rotor's direct axis (d-axis extending along the center line of the magnetic poles) and the quadrature axis (q-axis extending along the center line between the magnetic poles), allowing the motor to utilize a large amount of reluctance torque in addition to the permanent magnet torque during operation.

[0039] According to the rotor 1 and motor provided in this application, by adding multiple sets of second permanent magnets 12 with specific magnetization directions inside the multiple radially extending first permanent magnets 11 of the conventional spoke rotor 1, the magnetization direction of the first permanent magnets 11 is at a preset angle to the radial direction of the rotor core 10, and its magnetic flux contains a certain axial component. The first permanent magnets 11, as the main magnetic poles, can effectively suppress the problem of end magnetic leakage. The second permanent magnets 12, as auxiliary magnetic field regulators, have opposite magnetization directions between adjacent sets of second permanent magnets 12, so that at the shaft hole where the central axis of the rotor core 10 is located, the magnetic fields generated by the second permanent magnets 12 cancel each other out or form a local closed loop, forcing the magnetic flux outward to participate in the air gap mechanism. The electrical energy conversion effectively suppresses the leakage magnetic field problem in the rotor's central shaft hole. The edge gradient of the air gap magnetic field is adjusted by moving the magnetization direction of the second permanent magnet 12 away from / closer to the shaft center, which plays a role in magnetic concentration / splitting. The first permanent magnet 11 and the second permanent magnet 12 are arranged alternately in the circumferential direction with a ratio of 1:n (n≥3), which provides a high degree of freedom for electromagnetic design. This increases the harmonic order of the air gap magnetic flux density, enhances the fundamental amplitude, and significantly weakens the higher harmonics, thereby improving the utilization rate of the permanent magnets and facilitating the balance between high-speed magnetic field weakening and low-speed high torque. Thus, multiple technical effects are achieved simultaneously, such as suppressing the leakage magnetic field at the ends and center, and significantly improving the average torque. It has both excellent electromagnetic performance and industrial production feasibility.

[0040] In some embodiments, the first permanent magnet 11 is elongated, and a gap is formed between the first mounting groove 101 and the first permanent magnet 11.

[0041] The first permanent magnet 11 is elongated in shape, which simplifies the manufacturing process, makes it easy to produce and magnetize, and reduces manufacturing costs. Correspondingly, the first mounting groove 101 is a straight groove, which facilitates stamping die processing and can accommodate the relatively large volume of the first permanent magnet 11. As the main magnetic pole, the first permanent magnet 11 is the core component that generates the main magnetic field and the main permanent magnet torque. Its radial placement and alternating magnetic pole directions establish the basic number of pole pairs and the magnetic field framework of the motor 100.

[0042] A gap is provided between the first permanent magnet 11 and the first mounting groove 101. This gap can increase the magnetic resistance between the end of the first permanent magnet 11 and the rotor core 10, block the path of the first permanent magnet 11 directly short-circuiting to the end face of the rotor core 10, and weaken the magnetic flux leakage at the end. This gap can also provide tolerance space for the insertion of the first permanent magnet 11 and reserve a margin for thermal conductive adhesive filling or thermal expansion.

[0043] In some embodiments, the second permanent magnet 12 is elongated or arc-shaped, and the second mounting groove 102 is matched with the second permanent magnet 12.

[0044] The second permanent magnet 12 is elongated, and correspondingly, the second mounting groove 102 is elongated, making it easy to process, low in cost, and suitable for general-purpose motors. Alternatively, the second permanent magnet 12 can be arc-shaped, and correspondingly, the second mounting groove 102 can be arc-shaped. The arc shape better conforms to the natural direction of the magnetic lines of force inside the rotor, making the magnetic field of the second permanent magnet 12 more concentrated and more effectively coupled with the main magnetic field of the first permanent magnet 11, optimizing the magnetization effect, improving magnetic field regulation efficiency, and making it suitable for high torque density designs. It also reduces the problem of uneven magnetic reluctance in the magnetic circuit of the second permanent magnet 12, further improving the sinusoidal nature of the magnetic field and optimizing the magnetic flux distribution of the second permanent magnet 12. Compared to a straight strip shape, the arc-shaped structure of the second permanent magnet 12 can reduce magnetic reluctance at the corners of the magnetic circuit, making the flow of magnetic lines of force smoother, reducing unnecessary magnetic leakage, and lowering the possibility of magnetic flux leakage. In addition, the arc-shaped profile of the second permanent magnet 12 can eliminate sharp corners, which helps to disperse and reduce the mechanical stress borne by the second permanent magnet 12 and the rotor core 10 during high-speed rotation, especially the stress concentration caused by centrifugal force, thereby improving mechanical reliability.

[0045] Figure 3 for Figure 2 The diagram shows the magnetization direction distribution of each permanent magnet in the rotor. Figure 4 for Figure 3 An enlarged view of region A in the image.

[0046] In some embodiments, a local coordinate system is established with the center of the width direction along the circumference of any first permanent magnet 11 or second permanent magnet 12 as the origin, the length direction along the radial direction of the rotor core 10 as the Y-axis, and the direction perpendicular to the radial direction as the X-axis. Along the circumference of the rotor core 10, the angles between the magnetization directions of two adjacent first permanent magnets 11 and two sets of second permanent magnets 12 and the X-axis of their own local coordinate system are 0°, 360°*i / 2(n+1), i=1, 2, ..., n, 180° and 360°*k / 2(n+1), k=2n+1, 2n, ..., n+1, respectively.

[0047] like Figure 3 and Figure 4As shown, taking an example with 10 first permanent magnets 11, 10 groups of second permanent magnets 12, and n=3, a local coordinate system is established for each first permanent magnet 11 or second permanent magnet 12 with the center of the width along the circumference of the rotor core 10 as the origin, the length along the radial direction of the rotor core 10 as the Y-axis, and the direction perpendicular to the radial direction as the X-axis. Taking the vertical first permanent magnet 11 as the reference, the angles between the magnetization directions of two adjacent first permanent magnets 11 and two groups of second permanent magnets 12 and their respective local coordinate system's X-axis along the circumference of the rotor core 10 are 0°, 45°, 90°, 135°, 180°, 315°, 270°, and 225°. The magnetization direction of the second permanent magnet 12 matches the magnetization direction of the first permanent magnet 11, forming a periodically arranged Halbach array.

[0048] In other words, the angles between the magnetization directions of the multiple first permanent magnets 11 and the multiple sets of second permanent magnets 12 of the entire rotor 1 and the X-axis of its local coordinate system are uniformly sampled within the range of 0° to 360°, with a step size of Δθ = 360° / (2n+2). This means that the magnetization directions of the multiple first permanent magnets 11 and the multiple sets of second permanent magnets 12 along the circumference of the entire rotor 1 approximately constitute a continuously rotating vector field. All the first permanent magnets 11 and the second permanent magnets 12 participate in phase modulation, the magnetization angles are uniformly distributed, and the spatial distribution of the air gap magnetic flux density is closer to a sine wave.

[0049] In some embodiments, when n is an even number, the dimensions of the multiple sets of second permanent magnets 12 are all the same.

[0050] When n is an even number, such as n=4, 6, etc., rotor 1 has natural electromagnetic and geometric symmetry along the circumferential direction, ensuring magnetic field symmetry under an even number of poles, achieving perfect magnetic circuit mirror symmetry, and avoiding the introduction of even-order harmonics due to dimensional errors. This simplifies the structure while maintaining excellent torque performance. All the dimensions of the multiple second permanent magnets 12 are identical; for example, the width, thickness, and length dimensions of the multiple second permanent magnets 12 are all the same. The width dimension refers to the circumferential dimension of the second permanent magnet 12, the thickness dimension refers to the axial dimension of the second permanent magnet 12, and the length dimension refers to the radial dimension of the second permanent magnet 12. Since only one type of mold and tooling for the second permanent magnet 12 is needed, the design of automated magnetization and filling fixtures is simpler, reducing manufacturing and assembly complexity, and decreasing material management and incoming material inspection costs.

[0051] In some embodiments, when n is an odd number, each group of second permanent magnets 12 includes a first auxiliary permanent magnet 121 and a second auxiliary permanent magnet 122. The second auxiliary permanent magnet 122 is symmetrically arranged on both sides of the first auxiliary permanent magnet 121 along the circumference of the rotor core 10, and the size of the first auxiliary permanent magnet 121 is different from the size of the second auxiliary permanent magnet 122.

[0052] like Figure 3 As shown, when n is an odd number, for example, n=3, each group of second permanent magnets 12 is divided into a first auxiliary permanent magnet 121 and second auxiliary permanent magnets 122 symmetrically arranged on both sides of it. The dimensions of the first auxiliary permanent magnet 121 and the second auxiliary permanent magnets 122 are different. For example, at least one of the width, thickness and length dimensions of the multiple second permanent magnets 12 is different. This allows for the active construction of a "magnetic circuit compensation field" that is opposite to the distortion of an odd number of poles, effectively offsetting the inherent magnetic field distortion under an odd number of slots configuration. The first auxiliary permanent magnet 121 is responsible for main magnetic flux adjustment, while the second auxiliary permanent magnets 122 on both sides are used to handle edge magnetic flux and waveform flattening, achieving physical separation and synergy of functions, and significantly improving the sinusoidality of the air gap magnetic field.

[0053] In some embodiments, the width of the first auxiliary permanent magnet 121 along the circumferential direction of the rotor core is w1, and the thickness along the radial direction of the rotor core is h1. The width of the second auxiliary permanent magnet 122 along the circumferential direction of the rotor core is w2, and the thickness along the radial direction of the rotor core is h2, and the following conditions are satisfied: w2=(0.5~0.6)*w1, h2=(0.7~0.85)*h1.

[0054] When n is odd, the dimensions of the first auxiliary permanent magnet 121 and the second auxiliary permanent magnet 122 are different. For example, the radial length of the first auxiliary permanent magnet 121 is greater than that of the second auxiliary permanent magnet 122, and their width and thickness dimensions satisfy a preset proportional relationship. If the width and thickness of the second auxiliary permanent magnet 122 are too large, it will cause local saturation of the magnetic circuit inside the rotor, which will not only waste the magnet material, but may also cause serious magnetic leakage and heat generation problems; if the width and thickness of the second auxiliary permanent magnet 122 are too small, the compensation effect will be insufficient and it will be unable to effectively suppress odd-order harmonics. Therefore, this application has determined the dimensional ratio of the first auxiliary permanent magnet 121 and the second auxiliary permanent magnet 122 through a large number of simulations and experimental verifications, as shown below: w2=(0.5~0.6)*w1, h2=(0.7~0.85)*h1 By controlling the volume of the second auxiliary permanent magnet 122 within 35% to 50% of the volume of the first auxiliary permanent magnet 121, this specific ratio range ensures that the second auxiliary permanent magnet 122 can provide sufficient compensation magnetic flux without causing oversaturation of the inner magnetic circuit. This optimizes the magnetic flux contribution rate of each second permanent magnet 12 in each group, effectively reducing material costs and significantly improving the consistency and yield of mass production. Thus, it balances low torque pulsation with mass production capability and cost control.

[0055] In some embodiments, the rotor core 10 includes a plurality of silicon steel sheets stacked along its own axial direction. Each silicon steel sheet is provided with a first mounting hole and a second mounting hole. The first mounting holes of the plurality of silicon steel sheets are stacked to form a first mounting groove 101, and the second mounting holes of the plurality of silicon steel sheets are stacked to form a second mounting groove 102.

[0056] The rotor core 10 is formed by stacking multiple silicon steel sheets. Each silicon steel sheet is stamped with a first mounting hole and a second mounting hole. After the multiple silicon steel sheets are stacked, the multiple first mounting holes are stacked to form a first mounting groove 101, and the multiple second mounting holes are stacked to form a second mounting groove 102. The manufacturing process is mature.

[0057] Because silicon steel sheets have high resistivity and excellent magnetic permeability, they can greatly reduce eddy current losses and hysteresis losses generated by rotor 1 in high-speed alternating magnetic fields, thereby improving efficiency. Optionally, the surface of the silicon steel sheets is provided with an insulating coating, such as an oxide layer or a phosphate coating. The insulating coating has extremely high axial magnetic reluctance, making it difficult for magnetic flux to jump from one silicon steel sheet to another to form an axial loop, thus fundamentally cutting off the large-area leakage magnetic path along the axial end face of the rotor core 10.

[0058] In some embodiments, a boss is provided on one side of the central axis of the rotor core 10, which is used to mate with the rotating shaft. The boss is usually a keyway or interference fit structure, which is the standard mechanical connection method for transmitting drive torque between the rotor core 10 and the rotating shaft, ensuring reliable power output. For the motor 100 with an outer stator and an inner rotor, a shaft hole is provided at the center of the rotor core 10, and the boss is fixedly connected to the rotating shaft by interference fit, key connection, or heat sleeve to transmit torque, which helps to ensure the alignment of the rotor and the rotating shaft and reduce vibration during high-speed rotation. For the motor 100 with an outer rotor and an inner stator, a shaft hole is provided at the center of the stator, and the boss is fixedly connected to the rotating shaft by interference fit, key connection, or heat sleeve to transmit torque, which helps to ensure the alignment of the stator and the rotating shaft and reduce vibration during high-speed rotation.

[0059] Figure 5 A comparison chart of motor torque performance for four different permanent magnet configurations provided in the embodiments of this application. Figure 6 for Figure 5Enlarged view of the area within the dashed box.

[0060] like Figure 5 and Figure 6 As shown, the horizontal axis represents time (unit: ms), ranging from 0.0 to 2.0 ms, displaying a periodic segment in the motor's rotation process; the vertical axis represents instantaneous torque (unit: Nm), ranging from 2.0 Nm to 2.5 Nm, reflecting the magnitude of the motor's output torque; the graph includes four curves of different line types, corresponding to the average torque (Tavg) and torque ripple (Tripple) of four different permanent magnet configuration schemes. Details are as follows: No auxiliary permanent magnets: Using only the basic configuration, rotor 1 is equipped with only a few first permanent magnets 11, such as Figure 5 As shown by the dashed line, the corresponding average torque Tavg = 2.0424 Nm, and torque ripple Tripple = 4.56%; Non-uniform auxiliary permanent magnets: The rotor 1 is equipped with multiple first permanent magnets 11 and multiple sets of second permanent magnets 12, and the ratio of the number of first permanent magnets 11 to the number of second permanent magnets 12 is 1:3. Each set of second permanent magnets 12 includes one first auxiliary permanent magnet 121 and second auxiliary permanent magnets 122 symmetrically arranged on both sides thereof, and the width and thickness of the first auxiliary permanent magnets 121 and the second auxiliary permanent magnets 122 are different. Figure 6 As shown by the solid line, the corresponding average torque Tavg = 2.4015 Nm and torque ripple Tripple = 4.94%.

[0061] Non-uniform width, uniform thickness auxiliary permanent magnet: Similar in structure to the non-uniform auxiliary permanent magnet, but the first auxiliary permanent magnet 121 and the second auxiliary permanent magnet 122 have the same thickness, only the width is different, such as... Figure 6 As shown by the dashed line with arrows, the corresponding average torque Tavg = 2.3996 Nm and torque ripple Tripple = 4.94%.

[0062] Equal width and thickness auxiliary permanent magnets: Simultaneously optimize the first auxiliary permanent magnet 121 and the second auxiliary permanent magnet 122 to ensure that their width and thickness dimensions are the same, differing only in length. Figure 6 As shown by the dashed line, the corresponding average torque Tavg = 2.3861 Nm and torque ripple Tripple = 4.94%.

[0063] from Figure 5 and Figure 6It can be seen that the scheme without auxiliary permanent magnets, equipped only with the first permanent magnet 11, has the lowest average torque, at only 2.04224 Nm. Introducing the second permanent magnet 12 as an auxiliary permanent magnet significantly improves the average torque in all cases. Among them, the non-uniform auxiliary permanent magnet scheme shows the best improvement, reaching 2.4015 Nm, an increase of approximately 17.5% compared to the scheme without auxiliary magnets. The non-uniform width and equal thickness auxiliary permanent magnet scheme follows closely behind, with a torque of 2.3996 Nm. The equal width and equal thickness auxiliary permanent magnet scheme has a slightly lower torque of 2.3861 Nm. In other words, the introduction of the second permanent magnet 12 can significantly improve the average torque of the motor. The non-uniform auxiliary permanent magnet scheme has the most prominent effect on improving the average torque.

[0064] Furthermore, the scheme without auxiliary permanent magnets exhibited the lowest torque ripple at 4.56%. The torque ripple of all three schemes incorporating a second permanent magnet 12 as an auxiliary permanent magnet remained stable at around 4.94%, showing no significant difference, and was slightly higher than the scheme without auxiliary permanent magnets (from 4.56% to 4.94%). This indicates that the main limiting factor for torque ripple in this design is not the distribution of the second permanent magnet 12 (non-uniform width and thickness / equal width and thickness / non-uniform width and thickness). Although the torque ripple increased slightly, the significant increase in average torque (from 2.0424 Nm to 2.4015 Nm) far outweighed the slight increase in torque ripple, resulting in a significant improvement in overall performance.

[0065] In other words, by introducing multiple sets of second permanent magnets 12 as auxiliary permanent magnets on the basis of multiple first permanent magnets 11, the average torque of the motor can be significantly improved. Although the torque ripple increases slightly, the torque improvement is greater than the increase in ripple, resulting in overall performance optimization. The non-uniform auxiliary permanent magnet scheme has the best average motor torque, indicating that the non-uniform distribution of the magnets (or the refined design of their shape / position) can more efficiently enhance the main magnetic field and increase torque density. The torque ripple of the three schemes that introduce second permanent magnets 12 as auxiliary permanent magnets is similar, indicating that under this design framework, the "distribution form" of the second permanent magnets 12 has a limited effect on improving torque ripple. In the future, the magnet shape, magnetic barrier structure, or control strategy can be further optimized to reduce ripple.

[0066] Figure 7 Fourier decomposition comparison diagram of the air gap magnetic flux density of motors with two different permanent magnet configuration schemes provided in the embodiments of this application.

[0067] like Figure 7As shown, the amplitude distribution of air gap magnetic flux density at different harmonic orders in the motor without auxiliary permanent magnets is represented by a slanted bar, while the amplitude distribution of air gap magnetic flux density at different harmonic orders in the motor with non-uniform auxiliary permanent magnets is represented by a black bar. The horizontal axis represents the harmonic order (0-33), indicating the harmonic order of the air gap magnetic flux density; the vertical axis represents the amplitude of the air gap magnetic flux density (unit: T), reflecting the intensity of the harmonic.

[0068] Both schemes exhibit high fundamental (1st) amplitudes. The fundamental amplitude of the scheme without auxiliary permanent magnets is approximately 0.79T, while that of the scheme with non-uniform auxiliary permanent magnets is approximately 0.97T. The stronger fundamental amplitude of the scheme with non-uniform auxiliary permanent magnets helps to improve the fundamental magnetic flux and torque density of the motor. In the scheme without auxiliary permanent magnets, the amplitudes of higher harmonics such as the 3rd, 11th, and 13th are relatively high, for example, the 3rd is approximately 0.11T, the 11th is approximately 0.32T, and the 13th is approximately 0.24T. However, the scheme with non-uniform auxiliary permanent magnets significantly suppresses these higher harmonics, for example, the 3rd is approximately 0.08T, the 11th is approximately 0.3T, and the 13th is approximately 0.2T, resulting in a significant reduction in the overall amplitude of higher harmonics.

[0069] Therefore, the "non-uniform auxiliary permanent magnet" scheme can significantly enhance the fundamental magnetic flux density while greatly suppressing higher harmonics, especially the 3rd, 11th, and 13th harmonics, making the air gap magnetic flux density waveform closer to a sinusoidal distribution, thereby improving torque output. Compared to schemes such as "equal width and thickness auxiliary permanent magnets" or "non-uniform width and thickness auxiliary permanent magnets," the "non-uniform auxiliary permanent magnet" scheme has a clear advantage in suppressing torque ripple. In actual motor operation, low torque ripple means smoother output, lower noise, and lower vibration, which is crucial for applications such as high-performance servo motors and electric vehicle drive motors.

[0070] Therefore, the multi-permanent magnet collaborative design of this application embodiment, by reasonably matching the structure or magnetization direction of the first permanent magnet 11 and the second permanent magnet 12, can simultaneously achieve the dual goals of high torque and reduced leakage flux. In engineering practice, rotor structures with different magnetic circuit designs can be selected according to different application scenarios and usage requirements, effectively improving the overall performance of the motor, such as torque density, efficiency, and operational stability.

[0071] It should be understood that, in the embodiments of this application, unless otherwise expressly specified and limited, the terms "connection," "fixed connection," "contact," etc., should be interpreted broadly. Those skilled in the art can understand the specific meanings of the various terms in the embodiments of this application according to the specific circumstances.

[0072] It should also be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0073] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature and the second feature are in direct contact, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0074] It should also be understood that the terms “length,” “width,” “up,” “down,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship (if any) based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims. In conclusion, the above description is merely a preferred embodiment of the technical solution of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A rotor, characterized in that, include: The rotor core is provided with multiple first mounting slots and multiple sets of second mounting slots. The multiple first mounting slots are spaced apart along the circumference of the rotor core and extend radially along the rotor core. Each set of second mounting slots is disposed between two adjacent first mounting slots and is located close to the central axis of the rotor core. The first mounting slots and the set of second mounting slots are alternately placed along the circumference of the rotor core in a ratio of 1:n, where n≥3. A plurality of first permanent magnets are embedded in the first mounting slot. The magnetization direction of the first permanent magnets is set at a preset angle to the radial direction of the rotor core, and the magnetization directions of two adjacent first permanent magnets are opposite. Multiple sets of second permanent magnets are embedded in the second mounting slot. The magnetization direction of each set of second permanent magnets is away from or close to the central axis of the rotor core, and the magnetization directions of adjacent sets of second permanent magnets are opposite.

2. The rotor according to claim 1, characterized in that, The first permanent magnet is elongated, and a gap is formed between the first mounting groove and the first permanent magnet.

3. The rotor according to claim 1, characterized in that, The second permanent magnet is elongated or arc-shaped, and the second mounting groove is matched with the second permanent magnet.

4. The rotor according to claim 1, characterized in that, A local coordinate system is established with the center of the width direction along the circumference of the rotor core of any of the first permanent magnets or the second permanent magnets as the origin, the length direction along the radial direction of the rotor core as the Y-axis, and the direction perpendicular to the radial direction as the X-axis. Along the circumference of the rotor core, the angles between the magnetization directions of two adjacent first permanent magnets and two sets of second permanent magnets and the X-axis of their own local coordinate system are 0°, 360°*i / 2(n+1), i=1, 2, ..., n, 180° and 360°*k / 2(n+1), k=2n+1, 2n, ..., n+2, respectively.

5. The rotor according to claim 1, characterized in that, When n is an even number, the dimensions of multiple sets of the second permanent magnet are all the same.

6. The rotor according to claim 1, characterized in that, When n is an odd number, each group of the second permanent magnets includes a first auxiliary permanent magnet and a second auxiliary permanent magnet. The second auxiliary permanent magnets are symmetrically arranged on both sides of the first auxiliary permanent magnets along the circumference of the rotor core, and the size of the first auxiliary permanent magnet is different from that of the second auxiliary permanent magnet.

7. The rotor according to claim 6, characterized in that, The first auxiliary permanent magnet has a width of w1 along the circumference of the rotor core and a thickness of h1 along the radial direction of the rotor core. The second auxiliary permanent magnet has a width of w2 along the circumference of the rotor core and a thickness of h2 along the radial direction of the rotor core, and satisfies the following conditions: W2=(0.5~0.6)*w1, h2=(0.7~0.85)*h1.

8. The rotor according to any one of claims 2 to 7, characterized in that, The rotor core includes a plurality of silicon steel sheets stacked along its own axial direction. Each silicon steel sheet is provided with a first mounting hole and a second mounting hole. The first mounting holes of the plurality of silicon steel sheets are stacked to form a first mounting groove, and the second mounting holes of the plurality of silicon steel sheets are stacked to form a second mounting groove.

9. An electric motor, characterized in that, include: The rotor as described in any one of claims 1 to 8; and The stator is coaxially arranged with the rotor. The stator includes a stator core and an armature winding embedded in the stator core. An air gap is formed between the stator core and the rotor.

10. The motor according to claim 9, characterized in that, The stator is disposed on the outer periphery of the rotor; or, the rotor is disposed on the outer periphery of the stator.

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