Rotor structure and electric machine

Abstract

The application provides a rotor structure and a motor. The rotor structure comprises a rotor core (1), the rotor core (1) comprises a shaft hole (4), the rotor core (1) is formed by laminating a plurality of rotor laminations (2), a magnetic steel slot (3) extending in a radial direction is arranged on the rotor core (1) under one magnetic pole, a permanent magnet (5) is arranged in the magnetic steel slot (3), the permanent magnet (5) is magnetized in a direction perpendicular to a q-axis, the magnetization directions of two adjacent permanent magnets (5) are opposite, the surfaces of the permanent magnet (5) on both sides of the q-axis are curved surfaces, and in a cross section perpendicular to a central axis of the rotor core (1), the curve of the curved surface changes to meet λsin 2 α, wherein λ is a given parameter, and α is the change amount of the permanent magnet (5) from the shaft hole (4) to the outer circle of the rotor in the direction of the q-axis. According to the rotor structure, the motor harmonics and harmonic loss can be reduced, the torque ripple can be reduced, and the motor efficiency can be improved.

Description

Technical Field

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

[0002] Tangential permanent magnet synchronous motors (PMSMs) offer advantages such as high operating efficiency, large output torque, good reliability, and small size and weight. Based on a motor with an internal rotor structure, the PMSM combines the advantages of simultaneously generating permanent magnet torque and reluctance torque by changing the placement and magnetization direction of the magnets. The magnets are magnetized tangentially along the rotor core, with adjacent magnets magnetized in opposite directions. The magnetic flux of two magnets with a single pole pitch is connected in parallel, increasing the motor's magnetic flux density and thus increasing the output torque.

[0003] In current tangential permanent magnet motors, the magnetic field generated by the magnets interacts with the armature teeth to produce cogging torque, which leads to large torque pulsation and reduces the motor's efficiency. Summary of the Invention

[0004] The main objective of this invention is to provide a rotor structure and motor that can reduce motor harmonics and harmonic losses, reduce torque pulsation, and improve motor efficiency.

[0005] To achieve the above objectives, according to one aspect of the present invention, a rotor structure is provided, including a rotor core. The rotor core includes a shaft hole and is formed by stacking multiple rotor laminations. Under one magnetic pole, a radially extending magnetic slot is formed on the rotor core. A permanent magnet is disposed within the magnetic slot. The permanent magnet is magnetized in a direction perpendicular to the q-axis, and adjacent permanent magnets are magnetized in opposite directions. The surfaces of the permanent magnets on both sides of the q-axis are curved surfaces. In a cross-section perpendicular to the central axis of the rotor core, the curve of the curved surface satisfies λsinθ. 2 α, where λ is a given parameter, and α is the change in the permanent magnet along the q-axis from the shaft hole side to the outer circle of the rotor.

[0006] Furthermore, the radial outer surface and radial inner surface of the permanent magnet are planar.

[0007] Furthermore, the number of permanent magnets n is even, and the rotor core has n / 2 pairs of poles.

[0008] Furthermore, the length of the permanent magnet along the q-axis is L, and the width of the tangential surface of the permanent magnet is b, where b / L = 0.2 to 0.3.

[0009] Furthermore, the length of the permanent magnet along the q-axis is L, the radius of the rotor's outer circle is R, the radius of the shaft hole is r, and L / (Rr)≤0.8.

[0010] Furthermore, within a coordinate system with the center of the rotor core as the origin, a new coordinate system is established with the coordinates (0, R-δ-L / 2) as the new origin and the q-axis as the α-axis direction. Here, R is the radius of the rotor's outer circle, δ is the maximum distance between the side of the permanent magnet closest to the rotor core's outer circle and the outer circle itself, and L is the length of the permanent magnet along the q-axis. The surface within the range (-L / 2, L / 2) follows λsin... 2 The curve changes from (π / (2*L))-b / 2.

[0011] Furthermore, the permanent magnet and the magnetic groove are perfectly aligned in the q-axis direction and are both symmetrical about the q-axis.

[0012] Furthermore, the permanent magnet and the magnetic groove are fitted together on the side away from the shaft hole in the q-axis direction, while there is a gap on the side closer to the shaft hole.

[0013] Furthermore, when the length of the permanent magnet along the q-axis is L, the maximum width of the gap along the q-axis is m, and m / L≤0.2.

[0014] Furthermore, in a cross-section perpendicular to the central axis of the rotor core, the side of the magnet slot near the shaft hole is a straight line, a curve, or a combination of straight lines and curves, and the magnet slot is symmetrical about the q-axis.

[0015] Furthermore, the minimum distance between the side of the magnet slot near the shaft hole and the wall of the shaft hole is d, the radius of the outer circle of the rotor is R, the radius of the shaft hole is r, and d / (Rr) = 0.01~0.1.

[0016] Furthermore, the magnetic steel channel can be an open channel or a closed channel.

[0017] Furthermore, the maximum distance between the curved surfaces on both sides of the permanent magnet and the tangential surface of the permanent magnet is λ / 2, where 0 < λ ≤ b.

[0018] Furthermore, the minimum distance between the side of the magnetic steel groove near the shaft hole and the wall of the shaft hole is d, the radius of the shaft hole is r, and r / d = 9.5~10.

[0019] Furthermore, the permanent magnets are evenly spaced along the circumference with the center of the rotor core as the center. The circumferential distance between the two adjacent permanent magnets at their thickest points in the direction perpendicular to the q-axis is L1, where L1 = 2π(r+R) / (3*n) ~ π(r+R) / n.

[0020] According to another aspect of the present invention, an electric motor is provided, comprising a stator structure and a rotor structure, wherein the rotor structure is the rotor structure described above, and an air gap is formed between the stator structure and the rotor structure.

[0021] The rotor structure using the technical solution of this invention includes a rotor core, which includes a shaft hole. The rotor core is formed by stacking multiple rotor laminations. Under one magnetic pole, a magnetic slot extending radially is formed on the rotor core. A permanent magnet is disposed in the magnetic slot. The permanent magnet is magnetized in a direction perpendicular to the q-axis. The magnetization directions of two adjacent permanent magnets are opposite. The surfaces of the permanent magnets on both sides of the q-axis are curved surfaces. In a cross-section perpendicular to the central axis of the rotor core, the curve of the curved surface satisfies λsin 2 α, where λ is a given parameter, and α is the change in the thickness of the permanent magnet along the q-axis from the shaft hole side to the outer circle of the rotor. This rotor structure causes the thickness of the permanent magnet in the circumferential tangential direction to change with the corresponding position on the q-axis, and the pole arc coefficient of the rotor structure also changes accordingly. This alters the magnetic circuit of the permanent magnet in the d-axis direction, increases the sinusoidal nature of the air gap composite magnetic flux density, improves the harmonics of the motor's magnetic field, reduces harmonic losses, alleviates motor heating, and improves motor efficiency. By changing the permanent magnet structure of the motor, the pole arc coefficient changes, altering the magnetic field output by the permanent magnet, reducing the interaction between the magnetic field and the armature cogging, suppressing cogging torque, and improving the quality of the motor's output torque while ensuring the average output torque of the motor, reducing electromagnetic torque pulsation, and improving motor efficiency. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 A schematic diagram of the rotor structure according to an embodiment of the present invention is shown;

[0024] Figure 2 A schematic diagram of the permanent magnet structure of the rotor structure according to an embodiment of the present invention is shown;

[0025] Figure 3 A perspective view of the rotor structure according to an embodiment of the present invention is shown; and

[0026] Figure 4 A schematic diagram of a rotor structure according to another embodiment of the present invention is shown.

[0027] The above figures include the following reference numerals:

[0028] 1. Rotor core; 2. Rotor laminations; 3. Magnet slots; 4. Shaft holes; 5. Permanent magnets. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] See also Figures 1 to 4 As shown, according to an embodiment of the present invention, the rotor structure includes a rotor core 1, which includes a shaft hole 4. The rotor core 1 is formed by stacking multiple rotor laminations 2. Under one magnetic pole, a magnetic steel groove 3 extending radially is formed on the rotor core 1. A permanent magnet 5 is disposed in the magnetic steel groove 3. The permanent magnet 5 is magnetized in a direction perpendicular to the q-axis. The magnetization directions of two adjacent permanent magnets 5 are opposite. The surfaces of the permanent magnet 5 on both sides of the q-axis are curved surfaces. In a cross-section perpendicular to the central axis of the rotor core 1, the curve change of the curved surface satisfies λsin 2 α, where λ is a given parameter, and α is the amount of change of the permanent magnet 5 along the q-axis from the side of the shaft hole 4 toward the outer circle of the rotor.

[0031] This rotor structure causes the thickness of the permanent magnet 5 in the circumferential tangential direction to change with its corresponding position on the q-axis. This also alters the pole arc coefficient of the rotor structure, changing the magnetic circuit of the permanent magnet 5 in the d-axis direction, increasing the sinusoidal nature of the air gap's combined magnetic flux density, improving the harmonics of the motor's magnetic field, reducing harmonic losses, and alleviating motor heating. By changing the structure of the permanent magnet 5, the pole arc coefficient of the rotor structure changes, altering the magnetic field output by the permanent magnet 5. This reduces the mutual influence between the magnetic field and the armature's cogging teeth, suppressing cogging torque. While ensuring the average output torque of the motor, this improves the quality of the motor's output torque, reduces electromagnetic torque pulsation, and increases motor efficiency.

[0032] The permanent magnet 5 adopts a tangential magnetization method, which utilizes the magnetic focusing effect of the parallel output magnetic field of adjacent magnets to improve the torque density of the motor.

[0033] In this embodiment, by defining the curved surface shape on both sides of the q-axis of the permanent magnet 5 and ensuring that its thickness meets the definition of the curve formula, the structure of the permanent magnet 5 can be optimized, so that the structure on both sides of the q-axis of the permanent magnet 5 forms a curved surface structure. This allows the magnetic field generated by the permanent magnet 5 to be adjusted, improving the air gap magnetic flux density. The adjusted air gap magnetic flux density is more in line with the sinusoidal requirement, thereby effectively improving the harmonics of the motor magnetic field, suppressing cogging torque, and reducing electromagnetic torque pulsation.

[0034] In this embodiment, λsin 2 α is merely a constraint on the curve shape of the surfaces on both sides of the q-axis forming the permanent magnet 5. Therefore, α is the amount of change of the permanent magnet along the q-axis, and λ is a set parameter used to limit the convex height of the curve. The combined effect of λ and α can accurately define the surface shape of the permanent magnet 5, so that the structure designed for the permanent magnet 5 can accurately meet the design requirements.

[0035] In one embodiment, the radial outer surface and radial inner surface of the permanent magnet 5 are planes. The permanent magnet 5 can be processed and manufactured using the radial outer surface and radial inner surface of the permanent magnet 5 as a reference, thereby reducing the molding difficulty and improving the molding efficiency and manufacturing accuracy.

[0036] In one embodiment, the number n of permanent magnets 5 is even, and the rotor core 1 has n / 2 pairs of poles.

[0037] In one embodiment, the length of the permanent magnet 5 along the q-axis is L, and the tangential width of the permanent magnet 5 is b, where b / L = 0.2 to 0.3. In this embodiment, the tangential width refers to the minimum width of the permanent magnet 5 in the direction perpendicular to the q-axis, which is also the width of the outer and inner radial surfaces of the permanent magnet 5 along the q-axis.

[0038] By limiting the range of the b / L ratio, the length and tangential width ratio of the permanent magnet 5 can be reasonably limited, so that the permanent magnet 5 has a suitable length and width ratio. This ensures that the permanent magnet 5 has sufficient width to provide sufficient structural strength, and also ensures that the permanent magnet 5 has sufficient length to provide sufficient magnetic field to meet the torque requirements of the motor.

[0039] In one embodiment, the length of the permanent magnet 5 along the q-axis is L, the radius of the outer circle of the rotor is R, and the radius of the shaft hole 4 is r. L / (Rr)≤0.8, thereby limiting the proportion of the length of the permanent magnet 5 in the radial width of the rotor core 1, so that the rotor structure can leave sufficient dimensions at both ends of the permanent magnet 5 in the radial direction to ensure the mechanical strength of the rotor structure and prevent deformation of the rotor structure during movement.

[0040] In one embodiment, within a coordinate system with the center of rotor core 1 as the origin, a new coordinate system is established with coordinates 0, R-δ-L / 2 as the new origin and the q-axis direction as the α-axis direction. Here, R is the radius of the rotor's outer circle, δ is the maximum distance between the side of the permanent magnet 5 closest to the outer circle of rotor core 1 and the outer circle of rotor core 1, and L is the length of the permanent magnet 5 along the q-axis direction. The surface follows λsin... within the range of -L / 2, L / 2. 2 The curve changes from (π / (2*L))-b / 2.

[0041] In this embodiment, by transforming the coordinate system of the rotor core 1, a new coordinate system is formed with the center of the permanent magnet 5 as the origin and the q-axis direction as the α-axis direction. This allows for a more accurate determination of the surface curvature change trend on both sides of the permanent magnet 5 along the q-axis, which better conforms to the constraints of the rotor structure. In this embodiment, the shape of the magnetic poles of the permanent magnet 5 does not change in the axial direction, ensuring the stability of the magnetic pole structure.

[0042] The above formula allows for a more precise determination of the surface shape on both sides of the q-axis of the permanent magnet 5, using its own structure as a coordinate. This ensures that the thickness variation of the permanent magnet 5 meets the constraints of the above curve formula, thereby optimizing the structure of the permanent magnet 5. This results in a curved surface structure on both sides of the q-axis, which in turn allows for adjustment of the magnetic field generated by the permanent magnet 5, improving the air gap magnetic flux density. The adjusted air gap magnetic flux density better meets the sinusoidal requirements, effectively improving the harmonics of the motor magnetic field, suppressing cogging torque, and reducing electromagnetic torque pulsation.

[0043] In one embodiment, the permanent magnet 5 and the magnetic groove 3 are fully fitted in the q-axis direction and are both symmetrical about the q-axis.

[0044] In this embodiment, the shape of the permanent magnet 5 is adapted to the shape of the magnetic steel groove 3, so that the permanent magnet 5 can fall into the magnetic steel groove 3 just right. The structure of the magnetic steel groove 3 can be used to limit the installation structure of the permanent magnet 5. Since the permanent magnet 5 and the magnetic steel groove 3 are completely attached to the walls on both sides of the circumference, and the permanent magnet 5 is tangentially magnetized, the problem of the impact on the efficiency of magnetic lines of force caused by the gap between the permanent magnet 5 and the inner wall of the magnetic steel groove 3 can be effectively avoided. This ensures that the magnetic lines of force can travel more fully through both sides of the permanent magnet 5 and the rotor core 1 towards the outer circle of the rotor, ensuring the utilization efficiency of the permanent magnet 5 and improving the output torque of the motor.

[0045] In one embodiment, the permanent magnet 5 and the magnetic groove 3 are fitted together on the side away from the shaft hole 4 in the q-axis direction, while there is a gap on the side closer to the shaft hole 4.

[0046] In this embodiment, since the permanent magnet 5 is tangentially magnetized, a gap is formed between the permanent magnet 5 and the magnetic steel groove 3 on the side near the shaft hole 4. This does not affect the smooth arrival of the magnetic lines of force of the permanent magnet 5 onto the rotor core 1, effectively ensuring the magnetic field of the permanent magnet 5. Since there is a gap between the permanent magnet 5 and the inner wall of the magnetic steel groove 3 near the shaft hole 4, the mass of the rotor structure can be reduced.

[0047] In one embodiment, the gap is filled with a non-magnetic material. The non-magnetic material is lightweight and has non-magnetic properties, which can effectively increase magnetic resistance. Therefore, it will not affect the magnetic field lines of the permanent magnet 5, and can reduce the mass of the rotor structure. At the same time, it can also improve the stability of the installation structure of the permanent magnet 5 in the magnetic steel groove 3 and improve the mechanical strength of the rotor structure.

[0048] In one embodiment, when the length of the permanent magnet 5 along the q-axis is L, the maximum width of the gap along the q-axis is m, and m / L≤0.2.

[0049] By limiting the ratio between the length L of the permanent magnet 5 along the q-axis and the maximum width m of the gap along the q-axis, the air gap between the permanent magnet 5 and the magnetic groove 3 can be appropriately reduced. By utilizing the magnetic saturation effect, it is ensured that no magnetic leakage occurs near the rotating shaft. Furthermore, the use of non-magnetic materials for filling increases magnetic resistance, reduces magnetic leakage, and ensures that the position of the permanent magnet 5 is fixed.

[0050] In one embodiment, in a cross section perpendicular to the central axis of the rotor core 1, the side of the magnet slot 3 near the shaft hole 4 is a straight line, a curve, or a combination of a straight line and a curve, and the magnet slot 3 is symmetrical about the q-axis.

[0051] In one embodiment, the minimum distance between the side of the magnet slot 3 near the shaft hole 4 and the hole wall of the shaft hole 4 is d, the radius of the outer circle of the rotor is R, the radius of the shaft hole 4 is r, and d / (Rr) = 0.01~0.1.

[0052] By defining the relationship between d and R and r, the proportion of the distance between the inner wall of the magnet slot 3 near the shaft hole 4 and the shaft hole 4 in the radial width of the rotor core 1 can be defined. This ensures that the distance between the magnet slot 3 and the hole wall of the shaft hole 4 does not exceed 10% of the radial width of the rotor core 1, thus avoiding a decrease in the mechanical strength of the motor under the condition of reducing leakage flux.

[0053] In one embodiment, the magnet slot 3 is an open slot, which can more effectively avoid magnetic leakage, improve the magnetic field utilization rate of the permanent magnet 5, and increase the output torque of the motor.

[0054] In one embodiment, in order to improve the structural strength of the rotor core 1, a plastic insulating non-magnetic material can be used to wrap the outer periphery of the rotor core 1. This can more effectively fix the magnets and effectively improve the mechanical strength of the rotor structure.

[0055] In one embodiment, the minimum distance between the tangential surface of the permanent magnet 5 near the outer circle of the rotor and the outer circle of the rotor is the distance between the tangential surface and the outer circle of the rotor on the q-axis. The two tangential surfaces of the magnet slot 3 must be perpendicular to the q-axis, and the machining of the two curved surfaces of the permanent magnet 5 on both sides of the q-axis must maintain sufficient precision, ensuring that the axial structure of the permanent magnet 5 remains unchanged. For the location where the magnet slot 3 connects to the inner diameter of the rotor core 1, the dimensional design must ensure that magnetic circuit saturation prevents magnetic leakage within the motor's inner diameter, and also ensures that the motor has sufficient mechanical strength during operation to prevent deformation of the rotor core 1.

[0056] In one embodiment, the magnetic slot 3 is a closed slot, and a magnetic isolation bridge is formed between the outer circle of the rotor core 1 and the permanent magnet 5. The magnetic isolation bridge is not broken, so that the circumference of the rotor core 1 is complete and the outer circle of the rotor can remain continuous. While maintaining the performance of the motor, the processing difficulty is reduced, the mechanical strength of the rotor core 1 is enhanced, and the rotor core 1 is prevented from deforming during the movement.

[0057] In one embodiment, the maximum distance between the curved surfaces of the permanent magnet 5 on both sides of the q-axis and the tangential surface of the permanent magnet 5 is λ / 2, where 0 < λ ≤ b.

[0058] Limiting the distance between the curved surfaces on both sides of the q-axis and the tangent of the permanent magnet ensures the structural strength of the magnet slot and prevents deformation during motor operation.

[0059] In one embodiment, the minimum distance between the side of the magnetic groove 3 near the shaft hole 4 and the wall of the shaft hole 4 is d, the radius of the shaft hole 4 is r, and r / d = 9.5~10.

[0060] The distance between the magnet groove and the shaft hole is limited here to ensure that the value of d is small enough. This allows the magnetic saturation principle to be used to limit the direction of the magnetic lines of force, reduce magnetic leakage on the shaft, improve the utilization rate of the magnetic field, and protect the service life of the shaft.

[0061] In one embodiment, the permanent magnets 5 are evenly spaced along the circumference with the center of the rotor core 1 as the center. The circumferential distance between the highest point of the thickness of two adjacent permanent magnets 5 in the direction perpendicular to the q axis is L1, where L1 = 2π(r+R) / (3*n) ~ π(r+R) / n.

[0062] In this embodiment, the above-mentioned limitations can ensure that the distance between adjacent permanent magnets 5 and the distance between adjacent magnetic slots 3 are appropriate, thereby reducing the magnetic circuit saturation of the motor and weakening the output torque pulsation of the motor.

[0063] According to an embodiment of the present invention, the motor includes a stator structure and a rotor structure, the rotor structure being the rotor structure described above, and an air gap is formed between the stator structure and the rotor structure.

[0064] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0065] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rotor structure, characterized in that, The rotor core (1) includes a shaft hole (4) and is formed by stacking multiple rotor laminations (2). Under one magnetic pole, a radially extending magnetic groove (3) is formed on the rotor core (1). A permanent magnet (5) is placed within the magnetic groove (3). The permanent magnet (5) is magnetized in a direction perpendicular to the q-axis. The magnetization directions of two adjacent permanent magnets (5) are opposite. The surfaces of the permanent magnets (5) on both sides of the q-axis are curved. Within a cross-section perpendicular to the central axis of the rotor core (1), the curve of the curved surface satisfies λsinθ. 2 α, where λ is a given parameter, and α is the amount of change of the permanent magnet (5) along the q-axis from the shaft hole (4) to the outer circle of the rotor; In a coordinate system with the center of the rotor core (1) as the origin, a new coordinate system is established with coordinates (0, R-δ-L / 2) as the new origin and the q-axis direction as the α-axis direction. Here, R is the radius of the outer circle of the rotor, δ is the maximum distance between the side of the permanent magnet (5) closest to the outer circle of the rotor core (1) and the outer circle of the rotor core (1), L is the length of the permanent magnet (5) along the q-axis direction, and the tangential width of the permanent magnet (5) is b. The curved surface follows λsin... 2 The curve changes from (π / (2*L))-b / 2.

2. The rotor structure according to claim 1, characterized in that, The outer radial side and inner radial side of the permanent magnet (5) are planar.

3. The rotor structure according to claim 1, characterized in that, The number n of the permanent magnets (5) is even, and the rotor core (1) has n / 2 pairs of poles.

4. The rotor structure according to claim 1, characterized in that, The permanent magnet (5) has a length of L along the q-axis, and b / L = 0.2~0.

3.

5. The rotor structure according to claim 1, characterized in that, The permanent magnet (5) has a length of L along the q-axis, the outer circle of the rotor has a radius of R, the shaft hole (4) has a radius of r, and L / (Rr)≤0.

8.

6. The rotor structure according to any one of claims 1 to 5, characterized in that, The permanent magnet (5) and the magnetic groove (3) are completely fitted together in the q-axis direction and are both symmetrical about the q-axis.

7. The rotor structure according to any one of claims 1 to 5, characterized in that, The permanent magnet (5) and the magnetic groove (3) are attached to each other on the side away from the shaft hole (4) in the q-axis direction, and there is a gap on the side close to the shaft hole (4).

8. The rotor structure according to claim 7, characterized in that, When the length of the permanent magnet (5) along the q-axis is L, the maximum width of the gap along the q-axis is m, and m / L≤0.

2.

9. The rotor structure according to any one of claims 1 to 5, characterized in that, In a cross section perpendicular to the central axis of the rotor core (1), the side of the magnet slot (3) near the shaft hole (4) is a straight line, a curve, or a combination of a straight line and a curve, and the magnet slot (3) is symmetrical about the q axis.

10. The rotor structure according to any one of claims 1 to 5, characterized in that, The minimum distance between the side of the magnet slot (3) near the shaft hole (4) and the hole wall of the shaft hole (4) is d, the radius of the outer circle of the rotor is R, the radius of the shaft hole (4) is r, and d / (Rr) = 0.01~0.

1.

11. The rotor structure according to any one of claims 1 to 5, characterized in that, The magnet groove (3) is an open groove, or the magnet groove (3) is a closed groove.

12. The rotor structure according to claim 1, characterized in that, The maximum distance between the curved surface of the permanent magnet (5) on both sides of the q-axis and the tangential surface of the permanent magnet (5) is λ / 2, where 0 < λ ≤ b.

13. The rotor structure according to any one of claims 1 to 4, characterized in that, The minimum distance between the magnetic groove (3) near the shaft hole (4) and the hole wall of the shaft hole (4) is d, and the radius of the shaft hole (4) is r, r / d=9.5~10.

14. The rotor structure according to claim 1, characterized in that, The permanent magnets (5) are evenly spaced along the circumference with the center of the rotor core (1) as the center. The circumferential distance between the two adjacent permanent magnets (5) at the highest point of thickness in the direction perpendicular to the q axis is L1. The radius of the shaft hole (4) is r. The number of permanent magnets (5) n is an even number. L1 = 2π(r+R) / (3*n) ~ π(r+R) / n.

15. An electric motor comprising a stator structure and a rotor structure, wherein the rotor structure is the rotor structure according to any one of claims 1 to 14, and an air gap is formed between the stator structure and the rotor structure.

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