Permanent magnet array structure and electric machine

Abstract

The application discloses a permanent magnet array structure and a motor, and relates to the technical field of motors. The permanent magnet array structure comprises a plurality of permanent magnets arranged in a ring structure in sequence along a circumferential direction, the magnetization directions of the plurality of permanent magnets change in sequence along the circumferential direction, and the magnetization directions of the permanent magnets are not less than four. The plurality of permanent magnets comprise first magnetic steels and second magnetic steels which are alternately arranged along the circumferential direction, the first magnetic steels correspond to a central angle alpha, and the second magnetic steels correspond to a central angle beta. Wherein, the alpha and the beta satisfy alpha = beta + 180 DEG / p or alpha + beta = 180 DEG / p, and p is the pole pair number of the permanent magnet array structure. The permanent magnet array structure and the motor have the advantages that the anti-demagnetization capability is improved, and the reliability of work is improved.

Description

Technical Field

[0001] This disclosure relates to the field of motor technology, and more specifically, to a permanent magnet array structure and a motor. Background Technology

[0002] A permanent magnet array structure is a magnetic component that arranges multiple permanent magnets in a specific space to form a predetermined magnetic field distribution. It is widely used in permanent magnet motors, generators, magnetic levitation systems, magnetic bearings, and medical equipment. By rationally arranging the magnetization direction and spatial position of the permanent magnets, the desired magnetic field shape can be obtained in the target area, thereby meeting the special requirements of different application scenarios for magnetic field distribution.

[0003] However, during service, permanent magnet array structures are susceptible to demagnetization due to factors such as external reverse magnetic fields, temperature changes, and external impacts. This leads to a decrease in the magnetic field strength of the permanent magnets, resulting in problems such as reduced output performance and efficiency, which affect the normal operation of the equipment. Summary of the Invention

[0004] This disclosure provides a permanent magnet array structure and a motor, which helps to improve its anti-demagnetization ability and improve its operational reliability.

[0005] According to one aspect of this disclosure, a permanent magnet array structure is provided, comprising a plurality of permanent magnets arranged sequentially along the circumference to form a ring structure, wherein the magnetization direction of the plurality of permanent magnets changes sequentially along the circumference, and the magnetization direction of the permanent magnets is not less than four. Multiple permanent magnets include first and second magnets arranged alternately along the circumference, with the central angle corresponding to the first magnet being α and the central angle corresponding to the second magnet being β; Where α and β satisfy α=β+180° / p or α+β=180° / p, and p is the number of pole pairs of the permanent magnet array structure.

[0006] In one exemplary embodiment of this disclosure, α ≥ β, and α / β ≥ 2.

[0007] In one exemplary embodiment of this disclosure, p=3, α=50°, and β=10°.

[0008] In one exemplary embodiment of this disclosure, the outer peripheral surface of the permanent magnet array structure has a material removal modification area, at least a portion of which is located on a first magnet and at least a portion of which is located on a second magnet.

[0009] In one exemplary embodiment of this disclosure, the shape of the shaping area is symmetrical with respect to the radial centerline of the first magnet covered by the shaping area.

[0010] In one exemplary embodiment of this disclosure, the outer peripheral surface of the permanent magnet array structure has multiple shaping regions, each shaping region covering a first magnet and second magnets located on adjacent sides of the first magnet; for any shaping region, the outline of the first magnet is continuous with the outline of the second magnets on adjacent sides.

[0011] In one exemplary embodiment of this disclosure, the outer peripheral surface of the permanent magnet array structure has multiple shaping regions, each shaping region having the same shape; the number of shaping regions is 2p.

[0012] In one exemplary embodiment of this disclosure, the maximum depth of the shaping region along the radial direction of the permanent magnet array structure is no greater than 1 mm.

[0013] In one exemplary embodiment of this disclosure, the inner peripheral surface of the permanent magnet array structure has a plurality of first perforated areas for removing material, wherein at least a portion of any first perforated area is located on a first magnet and at least a portion is located on a second magnet.

[0014] In one exemplary embodiment of this disclosure, a first perforation area is provided between any first magnet and an adjacent second magnet.

[0015] According to another aspect of this disclosure, an electric motor is provided, including a rotor, the rotor comprising: Rotor core; The permanent magnet array structure of any of the preceding items is disposed on the outer peripheral surface of the rotor core.

[0016] In one exemplary embodiment of this disclosure, the rotor core has a plurality of second perforated areas for removing material; at least a portion of the second perforated areas corresponds radially to the first magnet, and at least a portion of the second perforated areas corresponds radially to the second magnet.

[0017] In one exemplary embodiment of this disclosure, the inner peripheral surface of the permanent magnet array structure has a plurality of first hole areas for removing material, each of the first hole areas being at least partially located on a first magnet and at least partially located on a second magnet; the first hole areas are connected to the second hole areas.

[0018] The permanent magnet array structure disclosed herein features adjacent permanent magnets with different magnetization directions. The magnetization directions of each permanent magnet change sequentially along the circumference, thereby creating a superimposed and enhanced magnetic field on one side of the permanent magnet array, while the magnetic fields on the other side cancel each other out, forming a Halbach array. For example, the magnetization directions of each permanent magnet (alternating first and second magnets) rotate sequentially along the circumference. When arranged on the rotor surface, this can create a concentrated and sinusoidally distributed magnetic field on the air gap side, which helps to improve the power density of the motor. The first magnet, as a focusing magnet, can form an enhanced magnetic field on one side of the permanent magnet array structure (e.g., the side facing the air gap); the second magnet, as the main magnetic field magnet, can cooperate with the focusing magnet to maintain the main magnetic flux path. When an external reverse magnetic field acts on the permanent magnet array structure of this disclosure, the magnetic field change at the interface between the first and second magnets is the most drastic, making it the region most prone to demagnetization. The width of the enhanced magnetic field (α angle reflection) and the width of the main magnetic field (β angle reflection) satisfy α=β+180° / p or α+β=180° / p, thus geometrically constraining the magnetic focusing path and the main magnetic path. This facilitates the smooth distribution of magnetic flux during the transition between the two types of magnets, avoids excessively high local magnetic flux density, and thus helps reduce the risk of demagnetization.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0021] Figure 1 This is a schematic diagram of an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0022] Figure 2 This is a schematic diagram showing the central angles of the first magnet and the second magnet in an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0023] Figure 3 This is a schematic diagram of the modification region in an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0024] Figure 4 This is a schematic diagram of the first perforated area in an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0025] Figure 5This is a schematic diagram of the second perforated area in an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0026] Figure 6 This is a schematic diagram of the first and second perforated areas in an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0027] Figure 7 This is a waveform diagram showing the change of back electromotive force over time before and after demagnetization in a permanent magnet array structure without a modification area, according to an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0028] Figure 8 This is a waveform diagram showing the back potential of a permanent magnet array structure with a modification area before and after demagnetization, in an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0029] Figure 9 This is a waveform diagram showing the change of back electromotive force over time of a rotor without a shaping area, a first hole area, and a second hole area in an exemplary embodiment of the permanent magnet array structure disclosed herein, before and after demagnetization.

[0030] Figure 10 This is a waveform diagram showing the change of back electromotive force over time of a rotor with a shaping area, a first hole area, and a second hole area before and after demagnetization, in an exemplary embodiment of the permanent magnet array structure disclosed herein.

[0031] Explanation of reference numerals in the attached figures: 10. First magnet; 20. Second magnet; 30. Shaping area; 41. First excavation area; 42. Second excavation area; 50. Rotor core; 60. Rotor shaft. Detailed Implementation

[0032] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0033] Unless otherwise specified or stated, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “a,” “an,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the terms “comprising” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to those listed; the terms “first” and “second” are used only as illustrative marks and are not intended to limit the number, importance, or order of the objects.

[0034] In the description of this application, it should be understood that "circumferential" refers to the direction around the circumference of the ring structure, and "radial" refers to the direction along the radius of the ring structure. The "magnetization direction" of the permanent magnet refers to the arrangement direction of the magnetic domains inside the permanent magnet, that is, the direction in which the N pole of the permanent magnet points to the S pole.

[0035] According to one aspect of this disclosure, a permanent magnet array structure is provided, comprising a plurality of permanent magnets arranged sequentially in a ring shape along the circumference. The magnetization directions of the plurality of permanent magnets change sequentially along the circumference, and the magnetization directions of the permanent magnets are not less than four. The plurality of permanent magnets include first magnets 10 and second magnets 20 arranged alternately along the circumference, with the central angle corresponding to the first magnet 10 being α and the central angle corresponding to the second magnet 20 being β. Wherein, α and β satisfy α = β + 180° / p or α + β = 180° / p, and p is the number of pole pairs of the permanent magnet array structure.

[0036] The permanent magnet array structure disclosed herein can be disposed on the outer peripheral surface of the rotor core 50 or on the surface of the rotor shaft. The first magnet 10 and the second magnet 20 can be neodymium iron boron permanent magnets or samarium cobalt permanent magnets. For example, refer to... Figure 1 This diagram illustrates a schematic of a permanent magnet array structure installed outside the rotor shaft 60 and rotor core 50 in an exemplary embodiment. It should be noted that the first magnet 10 and the second magnet 20 are arranged alternately on the circumference, i.e., first magnet 10, second magnet 20, first magnet 10, second magnet 20… and so on. The “central angle corresponding to the permanent magnet / magnet” mentioned in this disclosure can refer to the included angle between the two straight sides of the permanent magnet, i.e., the mechanical angle occupied by the permanent magnet in the annular structure. Specifically, the midlines of angles α and β both pass through the center of the outer circumferential arc of the magnet, while the two sides of angle β (i.e., the two sides adjacent to the first magnet 10) may not pass through the center of the outer circumferential arc of the magnet. The “number of pole pairs” p of the permanent magnet array structure described in this disclosure, as understood by those skilled in the art, refers to the number of magnetic pole pairs (N pole and S pole form a pair) formed by the annular array in the circumferential direction. When the permanent magnet array structure is installed in a motor, the number of pole pairs p is consistent with the number of pole pairs of the motor.

[0037] The permanent magnet array structure disclosed herein has adjacent permanent magnets with different magnetization directions. The magnetization directions of each permanent magnet change sequentially along the circumference, thereby forming a superimposed and enhanced magnetic field on one side of the permanent magnet array, while the magnetic fields on the other side cancel each other out, forming a Halbach array. For example, the magnetization directions of each permanent magnet (alternating first magnet 10 and second magnet 20) rotate sequentially along the circumference. When arranged on the rotor surface, a concentrated and sinusoidally distributed magnetic field can be formed on the air gap side, which helps to improve the power density of the motor. The first magnet 10, as a focusing magnet, can form an enhanced magnetic field on one side of the permanent magnet array structure (e.g., the side facing the air gap); the second magnet 20, as the main magnetic field magnet, can cooperate with the focusing magnet to maintain the main magnetic flux path.

[0038] However, permanent magnets in Halbach arrays are susceptible to demagnetization during operation due to external reverse magnetic fields. In permanent magnet motors, factors such as armature reaction magnetic fields, temperature changes, and external shocks can all exert a reverse demagnetizing magnetic field on the permanent magnets; in other applications such as magnetic levitation systems, external magnetic field disturbances can also lead to a decline in permanent magnet performance. Demagnetization results in a decrease in magnetic field strength, a degradation in output performance, and in severe cases, can render the equipment malfunctioning.

[0039] In the permanent magnet array structure disclosed herein, when an external reverse magnetic field acts on the permanent magnet array structure, the magnetic field change at the interface between the first magnet 10 and the second magnet 20 is the most drastic, and this is the region most prone to demagnetization. The width of the reinforcing magnetic field (α angle reflection) and the width of the main magnetic field (β angle reflection) satisfy α=β+180° / p or α+β=180° / p, thereby geometrically constraining the magnetic focusing path and the main magnetic path. This facilitates a smooth distribution of magnetic flux during the transition between the two types of magnets, avoids excessively high local magnetic flux density, and thus helps reduce the risk of demagnetization.

[0040] For example, in one exemplary embodiment of this disclosure, reference is made to Figure 2 As shown, α ≥ β, and α / β ≥ 2. When the angle α increases, the width of the magnetic focusing path increases. With a constant magnetic flux, the increased cross-sectional area of ​​the magnetic path leads to a decrease in magnetic flux density, which helps reduce the sensitivity of the magnetic focusing path to an external reverse magnetic field, thus improving demagnetization resistance. At the same time, the ratio of α to β should not be too large, for example, α / β ≤ 10, to avoid affecting the overall magnetic focusing effect due to an excessively narrow main magnetic field.

[0041] For example, in one exemplary embodiment, with p=3, the ratio of α to β was adjusted for testing, and the measured demagnetization rate is shown in Table 1 below.

[0042] Table 1:

[0043] Under the same conditions, the permanent magnet array structure with α=50° and β=10° in Table 1 has a demagnetization rate that is 3.13% lower than that with α=20° and β=40° in Table 1. It can be seen that, within a certain range, increasing the central angle α corresponding to the first magnet 10 has a positive effect on the overall demagnetization rate of the permanent magnet array structure.

[0044] In one exemplary embodiment of this disclosure, the number of pole pairs in the permanent magnet array structure can be 3, the central angle α corresponding to the first magnet 10 is 50°, and the central angle β corresponding to the second magnet 20 is 10°. Referring to Table 1 above, the overall demagnetization rate of the permanent magnet array structure can be improved. It should be noted that this exemplary embodiment is only one example of this application, and those skilled in the art can select different values ​​of α and β according to the actual number of pole pairs p and the requirements for magnetic focusing performance, based on the guidance of the foregoing exemplary embodiments of this disclosure.

[0045] In one exemplary embodiment of this disclosure, the outer peripheral surface of the permanent magnet array structure has a material removal trimming region 30, at least a portion of which is located on the first magnet 10 and at least a portion of which is located on the second magnet 20. (See reference...) Figure 3 As shown, the shaping region 30 can be formed by removing part of the material from the outer peripheral surface of the magnet. Its shape can be chamfered, arc-shaped, or other smooth non-sharp-cornered shapes. The shaping region 30 spans both the first magnet 10 and the second magnet 20. Specifically, the sharp corners of the magnet edges are prone to magnetic field convergence, forming local magnetic field distortion. When an external reverse magnetic field acts on this part, the local magnetic field distortion part is prone to become the starting point of demagnetization. In this exemplary embodiment, by providing the shaping region 30 on the outer peripheral surface of the permanent magnet array structure, the path of the magnetic field lines can be smoothed, making the direction of the magnetic field lines close to the shape of the shaping region 30, which helps to avoid excessive concentration of the magnetic field at the sharp corners. At the same time, the shaping region 30 can also increase the magnetic resistance on the path of the external reverse demagnetizing magnetic field, making it more difficult for the reverse magnetic field to penetrate the interior of the magnet, thereby improving the demagnetization resistance of the permanent magnet array structure.

[0046] In one exemplary embodiment of this disclosure, the shape of the shaping region 30 is symmetrical with respect to the radial centerline of the first magnet 10 covered by the shaping region 30. Specifically, referring to... Figure 3 As shown, the shape of the shaping region 30 can be symmetrical, and the center line of symmetry of the shaping region 30 coincides with the radial center line of the first magnet 10. Since the first magnet 10 is a concentrated magnet, it is a region where the magnetic field is concentrated. In this exemplary embodiment, the shaping region 30 is symmetrical about the radial center line of the first magnet 10, which is beneficial to make the magnetic field distribution on both sides of the shaping region 30 uniform and avoid causing new magnetic field distortion.

[0047] In one exemplary embodiment of this disclosure, the outer peripheral surface of the permanent magnet array structure has multiple shaping regions 30. Each shaping region 30 covers a first magnet 10 and two second magnets 20 located on either side of the first magnet 10. For any shaping region 30, the outline of the first magnet 10 is continuous with the outline of the second magnets 20 on both sides. Specifically, each shaping region 30 covers one first magnet 10 and two second magnets 20 adjacent to it on the left and right. The shaped magnet surface can smoothly transition at the junction of adjacent magnets, so that the magnetic field lines can smoothly transition when crossing the magnet junction, avoiding magnetic field distortion at the junction.

[0048] For example, the outer peripheral surface of the permanent magnet array structure has multiple modified regions 30. Each modified region 30 has the same shape, which helps improve the consistency of the circumferential magnetic properties of the permanent magnet array structure. The number of modified regions 30 is 2p, where p is the number of pole pairs. Specifically, each pole pair corresponds to two modified regions 30. For example, when p=3, the number of modified regions 30 is 6.

[0049] In one exemplary embodiment of this disclosure, the maximum radial depth of the shaping region 30 along the permanent magnet array structure is no greater than 1 mm. Specifically, the radial depth of the shaping region 30 described in this disclosure can refer to the maximum radial distance of material removed inward from the original outer circumferential surface of the magnet. In some embodiments, reference is made to... Figure 3 As shown, the shape of the shaping area 30 is symmetrical with respect to the radial centerline of the first magnet 10 covered by the shaping area 30, and the maximum value of the radial depth of the shaping area 30 along the permanent magnet array structure is located at the radial centerline of the first magnet 10. In this exemplary embodiment, the maximum depth of the shaping area 30 is no more than 1 mm, which can ensure the anti-demagnetization effect while avoiding excessive loss of effective magnet volume due to excessive shaping, thus affecting the output performance.

[0050] In one embodiment, under the same conditions, a demagnetization simulation experiment was conducted on a permanent magnet array structure with a modified region 30 (the maximum radial depth of the modified region 30 is 1 mm, and the width is 29.54 mm) and a permanent magnet array structure without the modified region 30. See the results. Figure 7 as well as Figure 8 As shown, Figure 7 , Figure 8 The waveforms of the back electromotive force (EMF) of the permanent magnet array structure before and after demagnetization are shown in the comparison. Specifically, Figure 7 , Figure 8 The horizontal axis represents time (in seconds), and the vertical axis represents the instantaneous value of the back electromotive force (EMF) (in V). The solid curve in the figure represents the back EMF waveform before demagnetization, and the dashed curve represents the back EMF waveform after demagnetization. Figure 7It is evident that in the unoptimized structure, the dashed waveform after demagnetization exhibits a more significant amplitude deviation compared to the solid waveform before demagnetization. This indicates that the demagnetization effect has a substantial impact on the magnetic properties of the permanent magnet array structure. In contrast, [the following text appears to be a continuation of the previous sentence and is likely a separate, unrelated statement:] ...by Figure 8 As can be seen, in the permanent magnet array structure optimized using this exemplary embodiment, despite undergoing demagnetization under the same conditions, the dashed waveform after demagnetization basically overlaps with the solid waveform before demagnetization, and the amplitude difference is relatively small. Calculations show that the optimized permanent magnet array structure reduces the demagnetization rate by approximately 1.52% compared to the permanent magnet array structure without the modification region 30. Experimental data demonstrates that appropriately setting the modification region 30 is beneficial for reducing the demagnetization rate of the permanent magnet array structure.

[0051] In one exemplary embodiment of this disclosure, the inner peripheral surface of the permanent magnet array structure has a plurality of first perforated areas 41 for material removal, wherein at least a portion of any first perforated area 41 is located on a first magnet 10 and at least a portion is located on a second magnet 20. Figure 4 , Figure 6 As shown, the first perforated area 41 can be a hole or cavity opened on the radial inner surface of the magnet. Since the magnetic permeability of air is lower than that of permanent magnet materials, in this exemplary embodiment, the first perforated area 41 can introduce a localized high magnetic reluctance region into the magnetic circuit, thereby blocking or altering the direction of magnetic field lines that originally passed through easily demagnetized areas (e.g., the area near the interface between magnets with different magnetization directions). This forces the magnetic field lines to bypass the first perforated area 41 and pass through other areas, thus changing the distribution of the magnetic circuit. This helps to disperse the magnetic flux density concentrated at the interface between the first magnet 10 and the second magnet 20, reducing the magnetic field strength in the interface area and protecting the demagnetization-sensitive area.

[0052] In one exemplary embodiment of this disclosure, a first perforated area 41 is provided between each first magnet 10 and an adjacent second magnet 20. In this exemplary embodiment, a first perforated area 41 is provided at the interface of each magnet. Since the interfaces between magnets with different magnetization directions (the interfaces between each first magnet 10 and the second magnet 20) are high-risk demagnetization areas, providing a first perforated area 41 at each interface can comprehensively cover demagnetization-sensitive locations. For example, the number of first perforated areas 41 can be 4p, where p is the number of pole pairs.

[0053] According to another aspect of this disclosure, an electric motor is provided, including a rotor, the rotor comprising: The rotor core 50, and the permanent magnet array structure of any of the foregoing exemplary embodiments and possible combinations thereof, wherein the permanent magnet array structure is disposed outside the outer peripheral surface of the rotor core 50, as referenced. Figure 1 , Figures 4 to 6As shown. The motor disclosed herein can be a permanent magnet synchronous motor, a brushless DC motor, or other types of permanent magnet motors. The motor of this disclosure adopts the aforementioned permanent magnet array structure, thus having stronger anti-demagnetization capability during operation, thereby improving the motor's operational reliability and service life.

[0054] In one exemplary embodiment of this disclosure, the rotor core 50 has a plurality of second perforated areas 42 for material removal; at least a portion of the second perforated areas 42 corresponds radially to the first magnet 10, and at least a portion of the second perforated areas 42 corresponds radially to the second magnet 20. (See reference...) Figure 5 As shown, the second perforated area 42 can be a hole or cavity opened on the rotor core 50 and located radially inside the permanent magnet array structure. The second perforated area 42 simultaneously covers the projected areas of the first magnet 10 and the second magnet 20 in the radial direction. The magnetic permeability of air is lower than that of permanent magnet materials. In this exemplary embodiment, the second perforated area 42 can introduce a local high magnetic resistance region on the rotor core 50, thereby blocking or changing the direction of magnetic field lines that originally passed through easily demagnetized areas (e.g., the area near the interface between the permanent magnet array structure and the rotor core 50, or the interface between the first magnet 10 and the second magnet 20 with different magnetization directions on the permanent magnet array structure). This forces the magnetic field lines to bypass the second perforated area 42 and pass through other areas, thereby changing the distribution of the magnetic circuit. This helps to reduce the magnetic field strength in the interface area and protect the demagnetization sensitive area.

[0055] For example, the first cutout area 41 can be provided simultaneously with the second cutout area 42. For instance, refer to... Figure 6 As shown, the inner circumferential surface of the permanent magnet array structure has multiple first perforated areas 41 for material removal. At least a portion of any first perforated area 41 is located on the first magnet 10 and at least a portion is located on the second magnet 20. The first perforated area 41 and the second perforated area 42 are connected. In some embodiments, a shaping area 30 is provided on the outer circumferential surface of the permanent magnet array structure, which can reduce the demagnetization rate by approximately 1.52%. Based on this, a demagnetization simulation experiment was conducted on a rotor with the first perforated area 41 and the second perforated area 42, and the results were compared with those of a rotor composed of a permanent magnet array structure without the shaping area 30 and without the first and second perforated areas 41 and 42. See the results below. Figure 9 as well as Figure 10 As shown, Figure 9 , Figure 10 The waveforms of the back EMF of the rotor before and after demagnetization are shown in the comparison.

[0056] Figure 10 This shows the setting of the trimming area 30 ( Figure 8Based on the corresponding embodiment, a circular hole with a diameter of 2mm is set to cover the projection area of ​​the first magnet 10 and the second magnet 20 as well as the rotor core 50, so as to form a waveform comparison of the back electromotive force of the permanent magnet array structure of the first hole area 41 and the second hole area 42 before and after demagnetization. Figure 9 , Figure 10 The horizontal axis represents time (in seconds), and the vertical axis represents the instantaneous value of the back electromotive force (EMF) (in V). The solid curve in the figure represents the back EMF waveform before demagnetization, and the dashed curve represents the back EMF waveform after demagnetization. Figure 9 and Figure 10 As can be seen from the comparison, in Figure 9 In the unoptimized structure shown, the dashed waveform after demagnetization exhibits a more significant amplitude deviation compared to the solid waveform before demagnetization, indicating that the demagnetization effect has a greater impact on the rotor's magnetic properties. In contrast, the structure before optimization... Figure 9 As can be seen, in the rotor optimized using this exemplary embodiment, despite undergoing the same demagnetization conditions, the dashed waveform after demagnetization essentially overlaps with the solid waveform before demagnetization, with relatively small amplitude differences. Calculations show that the optimized rotor, compared to the unoptimized rotor, further reduces the demagnetization rate to 1.65%, improving the motor's safety under extreme operating conditions.

[0057] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A permanent magnet array structure, characterized in that, It includes multiple permanent magnets arranged in a ring shape along the circumference, the magnetization directions of the multiple permanent magnets changing sequentially along the circumference, and the magnetization directions of the permanent magnets being no less than 4; The plurality of permanent magnets include a first magnet (10) and a second magnet (20) arranged alternately along the circumference, wherein the central angle corresponding to the first magnet (10) is α and the central angle corresponding to the second magnet (20) is β; Wherein, α and β satisfy α=β+180° / p or α+β=180° / p, and p is the number of pole pairs of the permanent magnet array structure.

2. The permanent magnet array structure according to claim 1, characterized in that, α≥β, and α / β≥2.

3. The permanent magnet array structure according to claim 2, characterized in that, p=3，α=50°，β=10°。 4. The permanent magnet array structure according to claim 1, characterized in that, The outer peripheral surface of the permanent magnet array structure has a material removal modification area (30), at least a portion of which is located on the first magnet (10) and at least a portion of which is located on the second magnet (20).

5. The permanent magnet array structure according to claim 4, characterized in that, The shape of the shaping area (30) is symmetrical with respect to the radial center line of the first magnet (10) covered by the shaping area (30).

6. The permanent magnet array structure according to claim 4, characterized in that, The outer peripheral surface of the permanent magnet array structure has a plurality of the shaping regions (30), each of the shaping regions (30) covering a first magnet (10) and a second magnet (20) located on the adjacent sides of the first magnet (10); for any of the shaping regions (30), the outline of the first magnet (10) is continuous with the outline of the second magnet (20) on the adjacent sides.

7. The permanent magnet array structure according to claim 4, characterized in that, The outer peripheral surface of the permanent magnet array structure has a plurality of the modified regions (30), each of the modified regions (30) having the same shape; the number of the modified regions (30) is 2p.

8. The permanent magnet array structure according to claim 4, characterized in that, The maximum depth of the modified area (30) along the radial direction of the permanent magnet array structure is no more than 1 mm.

9. The permanent magnet array structure according to claim 1, characterized in that, The inner circumferential surface of the permanent magnet array structure has a plurality of first hole areas (41) for removing material, at least a portion of any of the first hole areas (41) being located on the first magnet (10) and at least a portion being located on the second magnet (20).

10. The permanent magnet array structure according to claim 9, characterized in that, Each of the first magnets (10) and the adjacent second magnets (20) is provided with a first hole area (41).

11. An electric motor, characterized in that, The motor includes a rotor, and the rotor includes: Rotor core (50); The permanent magnet array structure according to any one of claims 1 to 10 is disposed on the outer peripheral surface of the rotor core (50).

12. The motor according to claim 11, characterized in that, The rotor core (50) has a plurality of second hollow areas (42) for removing material; at least a portion of the second hollow areas (42) corresponds radially to the first magnet (10), and at least a portion of the second hollow areas (42) corresponds radially to the second magnet (20).

13. The motor according to claim 12, characterized in that, The inner circumferential surface of the permanent magnet array structure has a plurality of first hole areas (41) for removing material, at least a portion of any first hole area (41) is located on the first magnet (10) and at least a portion is located on the second magnet (20); the first hole area (41) is connected to the second hole area (42).

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