Rotor punching sheet, rotor core and motor

Abstract

The invention discloses a rotor punching sheet, a rotor core and a motor, the rotor punching sheet comprises a punching sheet body, the inner side of the punching sheet body is provided with a plurality of linear magnetic steel grooves distributed along the circumferential direction, and the periphery of the punching sheet body is provided with concave edges recessed towards the center of the punching sheet body at positions corresponding to the magnetic steel grooves; wherein the concave edge is formed by connecting a section of semi-elliptic arc edge and two sections of broken line edges, the short axis of the semi-elliptic arc edge coincides with the d axis of the motor, and the two sections of broken line edges are connected to the two ends of the semi-elliptic arc edge respectively and are symmetrical about the d axis of the motor. According to the rotor punching sheet, the peripheral contour is designed to be of a special concave edge structure, the cogging torque and counter electromotive force distortion problem of the permanent magnet synchronous motor can be solved, and therefore the comprehensive performance and applicability of the motor are improved.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a rotor lamination, a rotor core, and a motor. Background Technology

[0002] With increasingly stringent global requirements for energy conservation and emission reduction, high-efficiency motors have become a crucial development direction in both industrial and household appliances. In applications such as refrigeration compressors, motor performance directly impacts the overall energy efficiency, noise level, and operational reliability of the machine. Permanent magnet synchronous motors, with their high efficiency, high power density, and excellent speed control performance, are gradually replacing traditional induction motors and becoming the preferred choice in the refrigeration compressor field.

[0003] However, in practical applications, existing permanent magnet synchronous motors still suffer from some inherent electromagnetic problems, among which cogging torque and back EMF waveform distortion are particularly prominent. Cogging torque originates from the interaction between the stator slots and the permanent magnets, and is a periodic torque pulsation that exists even when the motor is not energized. This torque fluctuation causes speed fluctuations during low-speed operation, resulting in vibration and noise, and severely affecting the smoothness of motor operation. On the other hand, back EMF waveform distortion is usually caused by factors such as imperfect magnetic field distribution of the permanent magnets, stator winding structure, or magnetic circuit saturation. Non-ideal sinusoidal back EMF affects current control accuracy, leading to uneven torque output, which in turn exacerbates motor vibration and noise, and may cause harmonic losses, reducing motor efficiency.

[0004] These issues not only hinder further improvements in the performance of permanent magnet synchronous motors but also affect the overall reliability and user experience. Therefore, optimizing the rotor structure to effectively suppress cogging torque and improve the back EMF waveform has become a key technical challenge in the field of permanent magnet synchronous motors. Summary of the Invention

[0005] This invention provides a rotor lamination, a rotor core, and a motor, which solves the technical problems of high vibration and noise and unstable operation caused by large cogging torque and severe back EMF waveform distortion in existing permanent magnet synchronous motors.

[0006] In a first aspect, embodiments of the present invention provide a rotor lamination, comprising: a lamination body having a plurality of I-shaped magnetic slots distributed along the circumferential direction on its inner side; and a concave edge concave towards the center of the lamination body being formed at a position corresponding to each magnetic slot on the outer periphery of the lamination body; wherein the concave edge is formed by connecting a semi-elliptical arc edge and two broken line edges, the minor axis of the semi-elliptical arc edge coinciding with the d-axis of the motor, and the two broken line edges respectively connecting to the two ends of the semi-elliptical arc edge and being symmetrical about the d-axis of the motor.

[0007] Furthermore, the broken line edge is formed by connecting the first straight line segment and the second straight line segment, and the vertex of the minor axis of the semi-elliptical arc edge is connected to the outer circle of the lamination body in sequence via the first straight line segment and the second straight line segment. The first straight line segment and the second straight line segment are both inclined relative to the d-axis of the motor, and the angle between the first straight line segment and the d-axis of the motor is greater than the angle between the second straight line segment and the d-axis of the motor.

[0008] Furthermore, the angle between the two ends of the concave edge and the center of the lamination body is set as θ, where 10°≤θ≤16°.

[0009] Furthermore, the angle between the two ends of the second straight line segment and the line connecting the center of the lamination body is set as α, where θ / 8≤α≤θ / 6.

[0010] Furthermore, the angle between the two ends of the first straight line and the line connecting the center of the lamination body is set as β, where β = θ / 3 - α.

[0011] Furthermore, the distance from the vertex of the minor axis of the semi-elliptical arc to the outer circle of the lamination body is set as L1, and the distance from the junction of the first straight line segment and the second straight line segment to the outer circle of the lamination body is set as L2, where L2 = 1 / 2 × L1.

[0012] Furthermore, the distance from the vertex of the minor axis of the semi-elliptical arc to the outer circle of the lamination body is set as L1, and the distance from the vertex of the major axis of the first straight line segment to the outer circle of the lamination body is set as L3, where L3 = 2 / 3 × L1.

[0013] Furthermore, 0.4mm≤L1≤0.6mm.

[0014] Furthermore, both ends of the magnetic steel groove are recessed towards the outer circle of the stamping body to form grooves. The outline of the groove is formed by connecting a semi-elliptical arc edge and two straight edges. The two straight edges are respectively connected to the two ends of the semi-elliptical arc edge and are parallel to the minor axis of the semi-elliptical arc edge. The length of the straight edge is equal to the length of the minor semi-axis of the semi-elliptical arc edge.

[0015] Furthermore, the length of the major axis of the semi-elliptical arc side is set as h1, where 1mm≤h1≤1.5mm.

[0016] Further, the length of the minor semi-axis of the semi-elliptical arc side is set as h2, the length of the magnet body installed to the magnet groove is set as t1, and the distance between the two ends of the magnet groove is set as t2, wherein 0.15mm≤h2≤Min(0.3mm,t2-t1).

[0017] Secondly, embodiments of the present invention provide a rotor core comprising the rotor laminations described in the first aspect.

[0018] Thirdly, embodiments of the present invention provide an electric motor that includes the rotor core described in the second aspect above.

[0019] This invention provides a rotor lamination, a rotor core, and a motor. The rotor lamination includes a lamination body with a plurality of I-shaped magnetic slots distributed circumferentially on its inner side. A concave edge is formed on the outer periphery of the lamination body at a position corresponding to each magnetic slot, concave towards the center of the lamination body. The concave edge is formed by a semi-elliptical arc edge and two symmetrical broken edges connected together. The minor axis of the semi-elliptical arc edge coincides with the d-axis of the motor. The two symmetrical broken edges are respectively connected to the two ends of the semi-elliptical arc edge and are symmetrical about the d-axis of the motor. The rotor lamination of this application, by setting a specific concave edge structure composed of a semi-elliptical arc edge and symmetrical broken edges at the position corresponding to the magnetic slot on the outer periphery of the lamination, can effectively optimize the magnetic field distribution, reduce the back EMF waveform distortion and cogging torque of the permanent magnet synchronous motor, thereby reducing the final torque pulsation and vibration noise, and improving the stability of motor operation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 An axial view of the rotor lamination provided in an embodiment of the present invention; Figure 2 for Figure 1 Enlarged view of part A; Figure 3 for Figure 2 Dimensioning drawing; Figure 4 This is a partially enlarged dimensional annotation diagram of the rotor lamination provided in an embodiment of the present invention; Figure 5 This is a partially enlarged dimensional annotation diagram of the rotor lamination provided in an embodiment of the present invention; Figure 6 for Figure 1 Enlarged view of part B; Figure 7 for Figure 6 Dimensioning drawing; Figure 8 This is a dimensional annotation diagram of the rotor laminations and magnet body in their assembled state according to an embodiment of the present invention; Figure 9 A comparison diagram of the no-load back EMF waveforms between the conventional lamination scheme and the lamination scheme of this application; Figure 10 A bar chart comparing the total harmonic distortion (THD) parameters of the no-load back EMF between the conventional stamping scheme and the stamping scheme of this application; Figure 11 The instantaneous diagram of cogging torque for a conventional lamination design; Figure 12 This is an instantaneous diagram of the cogging torque of the lamination design in this application; Figure 13 An axial view of the rotor core provided in an embodiment of the present invention.

[0022] The labels for the attached figures are as follows: 100. Rotor lamination; 10. Lamination body; 101. Magnet slot; 11. Concave edge; 1. Semi-elliptical arc edge; 2. Broken line edge; 21. First straight segment; 22. Second straight segment; 12. Groove; 121. Straight edge; 13. Outer circle; 30. Magnet body; 200. Rotor core. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The directional terms used in this invention, such as "up," "down," "front," "back," "left," "right," "inner," "outer," and "side," are merely for reference to the accompanying drawings. Therefore, the directional terms used are for illustrating and understanding this invention, and not for limiting it. Furthermore, in the drawings, structures that are similar or identical are indicated by the same reference numerals.

[0025] See Figures 1 to 8 This invention provides a rotor lamination 100, which can be referred to in detail. Figure 1 and Figure 2 The rotor lamination 100 includes: a lamination body 10, on which a plurality of I-shaped magnetic slots 101 are formed on the inner side and distributed along the circumferential direction; a concave edge 11 is formed on the outer periphery of the lamination body 10 at a position corresponding to each of the magnetic slots 101, which is recessed toward the center of the lamination body 10; wherein, the concave edge 11 is formed by connecting a semi-elliptical arc edge 1 and two broken line edges 2, the minor axis of the semi-elliptical arc edge 1 coincides with the d-axis of the motor, and the two broken line edges 2 are respectively connected to the two ends of the semi-elliptical arc edge 1 and are symmetrical about the d-axis of the motor.

[0026] In practical implementation, regarding the back electromotive force (EMF), when the permanent magnet synchronous motor rotates under no-load, the relative motion between the magnets and the stator windings causes the magnetic flux linkage of the stator windings to continuously change, thus generating the no-load back EMF. The calculation is as follows: ,in, It is the back electromotive force. It is through the magnetic flux of this phase winding. It's angular velocity. This is the rotor position angle. Therefore, when the rotational speed... At a given time, the waveform of the back electromotive force is proportional to the derivative of the flux linkage with respect to the rotor position angle, while the flux linkage... It is the air gap magnetic flux density The integral over the winding distribution space means that the waveform of the air gap magnetic flux density determines the waveform of the back EMF to a certain extent.

[0027] Ideally, the air gap magnetic flux density waveform is an almost perfect sine and cosine waveform. However, in reality, various factors lead to distortion of the air gap magnetic flux density. Due to the symmetry of the rotor assembly and the air gap magnetic flux density... It also exhibits periodicity, so its Fourier series decomposition yields: Where p is the number of pole pairs of the motor. It is the amplitude of the nth air gap magnetic flux density harmonic. Due to the combined effect of the air gap magnetic flux density harmonic and the winding distribution effect, the main components in the back EMF harmonic are odd-order harmonics. For a three-phase symmetrical winding motor, the 3rd and multiples of the 3rd harmonics in the back EMF will cancel each other out. Therefore, the larger harmonic components in the back EMF are often the 5th, 7th and 11th.

[0028] For cogging rotors, the cogging torque originates from the change in magnetic field energy caused by the interaction between the permanent magnet and the stator slot. It is equal to the negative derivative of the magnetic field energy W with respect to the rotor position angle θ, that is: Where W is the air gap magnetic field energy in the entire motor system. Assuming that the permeability of the iron core is much larger than that of the air gap, then almost all the energy of the magnetic field is stored in the air gap. Therefore, the amplitude of the cogging torque will be related to the amplitude of a specific subharmonic component in the air gap magnetic flux density of the permanent magnet as follows: ,in, The number of stator slots It is the permeability harmonic coefficient related to the stator slot opening. In the Fourier series of the permanent magnet air gap magnetic flux density, the order is... The amplitudes of those specific harmonic components.

[0029] Therefore, it can be seen that by reasonably reducing the amplitude of harmonic components in the air gap magnetic flux density, the distortion of the no-load back EMF waveform and the magnitude of the cogging torque can be reduced simultaneously, thereby reducing the vibration and noise of the motor operation and improving stability.

[0030] To achieve the above objectives, the rotor lamination design in this embodiment is as follows: like Figure 1 As shown, the rotor lamination 100 includes a lamination body 10, which is the main part of the rotor lamination 100. It is usually designed with silicon steel sheets. Several magnetic steel slots 101 arranged in a straight line and distributed along the circumferential direction are provided on the inner side of the lamination body 10. The magnetic steel slots 101 are slot structures for mounting the magnets 30. All the magnetic steel slots 101 are evenly distributed in the circumferential direction and the distance between them is the same.

[0031] like Figure 2 As shown, a concave edge 11 is provided on the outer periphery of the lamination body 10 at a position corresponding to each magnet slot 101. The concave edge 11 is recessed towards the center of the lamination body 10, and the concave edge 11 is part of the outer contour of the lamination body 10, that is, each magnetic pole corresponds to one concave edge 11. The concave edge 11 is formed by connecting a semi-elliptical arc edge 1 and two broken line edges 2. Specifically, the semi-elliptical arc edge 1 is shaped as a semi-ellipse bisected by the major axis of an ellipse. Figure 2 As shown, the dashed line d represents the d-axis of the motor. In the field of motors, the d-axis is also called the direct axis, which refers to the direction of the center line of the rotor magnetic poles. In this embodiment, the d-axis of the motor specifically refers to the bisector of the magnetic slot 101. The minor axis of the semi-elliptical arc side 1 coincides with the d-axis of the motor, and the d-axis of the motor divides the semi-elliptical arc side 1 into two symmetrical halves. The broken edge 2 is in the shape of a broken line, and each segment of the broken edge 2 can be formed by connecting at least two straight lines. The two segments of the broken edge 2 are respectively connected to the two ends of the semi-elliptical arc side 1 and are symmetrical about the d-axis of the motor. The two ends of the semi-elliptical arc side 1 are also the two vertices of the major axis of the semi-elliptical arc side 1. Overall, the vertex of the minor axis of the semi-elliptical arc is the closest point of the concave edge 11 to the center of the lamination body 10, while the end of the broken edge 2 away from the semi-elliptical arc side 1 is the farthest point of the concave edge 11 from the center of the lamination body 10. By combining the semi-elliptical arc edge 1 and the broken line edge 2 as part of the outer contour of the center of the lamination body 10, corresponding to the magnetic pole, this design can change the distribution of the magnetic field in actual motor applications, thereby effectively improving the cogging torque and back EMF distortion problems of permanent magnet synchronous motors.

[0032] In one embodiment, reference is made to Figure 2 The broken line edge 2 is formed by connecting the first straight line segment 21 and the second straight line segment 22. The vertex of the minor axis of the semi-elliptical arc edge 1 is connected to the outer circle 13 of the lamination body 10 via the first straight line segment 21 and the second straight line segment 22 in sequence. The first straight line segment 21 and the second straight line segment 22 are both inclined relative to the motor d-axis, and the angle between the first straight line segment 21 and the motor d-axis is greater than the angle between the second straight line segment 22 and the motor d-axis.

[0033] In specific implementation, the broken edge 2 is designed as a combination of two straight lines. The broken edge 2 is formed by connecting the first straight line segment 21 and the second straight line segment 22. The connection point between the first straight line segment 21 and the second straight line segment 22 is the inflection point. The first straight line segment 21 serves as the part connecting to the semi-elliptical arc edge 1 and the part connecting to the outer circle 13 of the lamination body 10. The vertex of the minor axis of the semi-elliptical arc edge 1 is connected to the outer circle 13 of the lamination body 10 via the first straight line segment 21 and the second straight line segment 22 in sequence. Both the first straight line segment 21 and the second straight line segment 22 are inclined at a certain angle relative to the d-axis of the motor. In the design, the angle between the first straight line segment 21 and the d-axis of the motor is greater than the angle between the second straight line segment 22 and the d-axis of the motor. Thus, in the radial direction of the lamination body 10, the concave edge 11 forms a broken line with a steep first and then gentler shape from the second straight line segment 22 to the first straight line segment 21. In actual motor applications, this design can effectively improve the magnetic field distribution and reduce the amplitude of the back EMF harmonic component.

[0034] Furthermore, referring to Figure 3 The angle between the two ends of the concave edge 11 and the center of the stamping body 10 is set as θ, where 10°≤θ≤16°.

[0035] In practical implementation, the span between the two ends of the concave edge 11 can affect the magnetic field distribution, therefore it needs to be designed reasonably. In this embodiment, θ represents the angle between the two ends of the concave edge 11 and the center of the lamination body 10, such as... Figure 3 As shown, the dashed lines m and n represent the lines connecting the two ends of the concave edge 11 to the center of the lamination body 10, and the angle between the dashed lines m and n is θ. In the design, 10° ≤ θ ≤ 16°, meaning the angle between the two ends of the concave edge 11 and the center of the lamination body 10 is designed to be within the range of 10° to 16°, with a minimum of 10° and a maximum of 16°. Verification has shown that this design can ensure a reduction in the amplitude of harmonic components without easily introducing new harmonic components, effectively improving the sinusoidal nature of the back EMF waveform.

[0036] Furthermore, referring to Figure 4 The angle between the two ends of the second straight segment 22 and the center of the lamination body 10 is set as α, where θ / 8≤α≤θ / 6.

[0037] In specific implementation, the angle between the two ends of the second straight segment 22 and the center of the lamination body 10 determines its span in the circumferential direction of the lamination body 10. The larger the angle between the two ends of the second straight segment 22 and the center of the lamination body 10, the larger the span of the second straight segment 22 in the circumferential direction of the lamination body 10. The angle between the two ends of the second straight segment 22 and the center of the lamination body 10 also affects the distribution of the magnetic field; therefore, the span of the second straight segment 22 needs to be reasonably designed. In this embodiment, α represents the angle between the two ends of the second straight segment 22 and the center of the lamination body 10. Figure 4 As shown, dashed lines m and a represent the lines connecting the two ends of the second straight segment 22 to the center of the lamination body 10, and the angle between dashed lines m and a is α. θ represents the angle between the two ends of the concave edge 11 and the center of the lamination body 10. In the design, θ / 8 ≤ α ≤ θ / 6, that is, the angle between the two ends of the second straight segment 22 and the center of the lamination body 10 is designed to be 1 / 8 to 1 / 6 of the angle between the two ends of the concave edge 11 and the center of the lamination body 10. In this way, the span of the two ends of the second straight segment 22 accounts for 1 / 8 to 1 / 6 of the span of the entire concave edge 11, which enables a smooth transition between the outer circle 13 of the annular lamination body 10 and the semi-elliptical arc edge 1, making the magnetic field distribution more uniform and the changes more gradual, thereby effectively reducing the back EMF harmonic amplitude.

[0038] Furthermore, referring to Figure 4 The angle between the two ends of the first straight line and the center of the lamination body 10 is set as β, where β = θ / 3 - α.

[0039] In specific implementation, the angle between the two ends of the first straight segment 21 and the center of the lamination body 10 determines its span in the circumferential direction of the lamination body 10. Besides the reasonable design of the span of the second straight edge 121, the span of the first straight segment 21 also needs to be reasonably designed. In this embodiment, the span design of the first straight segment 21 is related to the span design of the second straight segment 22. β represents the angle between the two ends of the first straight segment 21 and the center of the lamination body 10. Figure 4 As shown, dashed lines a and b represent the lines connecting the two ends of the first straight segment 21 to the center of the lamination body 10, and the included angle between dashed lines a and b is β. α represents the angle connecting the two ends of the second straight segment 22 to the center of the lamination body 10, and θ represents the angle connecting the two ends of the concave edge 11 to the center of the lamination body 10. In the design, β = θ / 3 - α, that is, the angle between the two ends of the first straight segment 21 and the center of the lamination body 10 is designed to be one-third of the angle between the two ends of the concave edge 11 and the center of the lamination body 10 minus the angle between the two ends of the second straight segment 22 and the center of the lamination body 10. This makes the transition between the outer circle 13 of the annular lamination body 10 and the semi-elliptical arc edge 1 smooth, making the magnetic field distribution more uniform and the changes gentler, and reducing the back EMF harmonic amplitude.

[0040] In one embodiment, reference is made to Figure 5 The distance from the vertex of the minor axis of the semi-elliptical arc side 1 to the outer circle 13 of the stamping body 10 is set as L1, and the distance from the junction of the first straight line segment 21 and the second straight line segment 22 to the outer circle 13 of the stamping body 10 is set as L2, where L2 = 1 / 2 × L1.

[0041] In practice, the distance from the vertex of the minor axis of the semi-elliptical arc edge 1 to the outer circle 13 of the stamping body 10 determines the degree of concavity of the entire concave edge 11. The junction of the first straight line segment 21 and the second straight line segment 22 is the inflection point between them. The distance from the junction of the first straight line segment 21 and the second straight line segment 22 to the outer circle 13 of the stamping body 10 determines the smoothness of the broken line edge 2. In this embodiment, L1 represents the distance from the vertex of the minor axis of the semi-elliptical arc 1 to the outer circle 13 of the lamination body 10, and L2 represents the distance from the junction of the first straight line segment 21 and the second straight line segment 22 to the outer circle 13 of the lamination body 10. In the design, L2 = 1 / 2 × L1, that is, the distance from the junction of the first straight line segment 21 and the second straight line segment 22 to the outer circle 13 of the lamination body 10 is equal to half the distance from the vertex of the minor axis of the semi-elliptical arc 1 to the outer circle 13 of the lamination body 10. This design relationship can make the transition between the outer circle 13 of the annular lamination body 10 and the semi-elliptical arc 1 smoother, make the magnetic field distribution more uniform and the change more gradual, and reduce the back EMF harmonic amplitude.

[0042] In one embodiment, reference is made to Figure 5 The distance from the vertex of the minor axis of the semi-elliptical arc 1 to the outer circle 13 of the lamination body 10 is set as L1, and the distance from the point where the first straight line segment 21 connects to the vertex of the major axis of the semi-elliptical arc segment to the outer circle 13 of the lamination body 10 is set as L3, where L3 = 2 / 3 × L1.

[0043] In practice, the distance from the vertex of the minor axis of the semi-elliptical arc 1 to the outer circle 13 of the stamping body 10 determines the degree of concavity of the entire concave edge 11, and the connection between the first straight line segment 21 and the vertex of the major axis of the semi-elliptical arc segment determines the smoothness of the transition from the first straight line segment 21 to the semi-elliptical arc 1. In this embodiment, L1 represents the distance from the vertex of the minor axis of the semi-elliptical arc 1 to the outer circle 13 of the lamination body 10, and L3 represents the distance from the point where the first straight line segment 21 connects to the vertex of the major axis of the semi-elliptical arc segment to the outer circle 13 of the lamination body 10. In the design, L3 = 2 / 3 × L1, that is, the distance from the point where the first straight line segment 21 connects to the vertex of the major axis of the semi-elliptical arc segment to the outer circle 13 of the lamination body 10 is equal to two-thirds of the distance from the vertex of the minor axis of the semi-elliptical arc 1 to the outer circle 13 of the lamination body 10. This design relationship can make the transition from the broken line edge 2 part to the semi-elliptical arc edge 1 part smoother, thereby making the transition between the outer circle 13 of the annular lamination body 10 and the semi-elliptical arc edge 1 smoother, making the magnetic field distribution more uniform and the change gentler, and reducing the back EMF harmonic amplitude.

[0044] Preferably, 0.4mm ≤ L1 ≤ 0.6mm. In specific implementations, the distance from the vertex of the minor axis of the semi-elliptical arc edge 1 to the outer circle 13 of the lamination body 10 determines the degree of concavity of the entire concave edge 11. If the distance is too large, it will reduce the mechanical strength of the rotor core and significantly reduce the effective value of the back electromotive force (EMF). If the distance is too small, it cannot effectively modulate the magnetic field and improve the magnetic field distribution. Therefore, a reasonable design is required. In this embodiment, L1 represents the distance from the vertex of the minor axis of the semi-elliptical arc edge 1 to the outer circle 13 of the lamination body 10. In the design, 0.4mm ≤ L1 ≤ 0.6mm, that is, the distance from the vertex of the minor axis of the semi-elliptical arc edge 1 to the outer circle 13 of the lamination body 10 is designed within the range of 0.4mm to 0.6mm. This design ensures the mechanical strength of the rotor core, does not reduce the effective value of the back EMF, and can effectively improve the magnetic field distribution and reduce the harmonic amplitude of the back EMF.

[0045] In one embodiment, reference is made to Figure 1 , Figure 6 as well as Figure 7 Both ends of the magnetic steel groove 101 are recessed towards the outer circle 13 of the stamping body 10 to form grooves 12. The outline of the groove 12 is formed by connecting a semi-elliptical arc edge 1 and two straight edges 121. The two straight edges 121 are respectively connected to the two ends of the semi-elliptical arc edge 1 and are parallel to the minor axis of the semi-elliptical arc edge 1. The length of the straight edge 121 is equal to the length of the minor semi-axis of the semi-elliptical arc edge 1.

[0046] In practical implementation, the slot of a traditional lamination is usually designed with a right-angle structure. This design has mechanical reliability issues, such as stress concentration at the right-angled edges and insufficient resistance to centrifugal force loads on the magnetic bridge during high-speed rotation. Electromagnetically, the right-angled edges cause a sharp change in magnetic flux, easily leading to localized magnetic saturation and flux congestion. To improve these problems, in this embodiment, a groove 12 is provided at each end of the magnetic slot 101. The groove 12 is recessed towards the outer circle 13 of the lamination body 10. The contour of the groove 12 is formed by a semi-elliptical arc edge 1 and two straight edges 121 connected together. The two straight edges 121 are respectively connected to the two ends of the semi-elliptical arc edge 1, and both straight edges 121 are parallel to the minor axis of the semi-elliptical arc edge 1. Furthermore, the length of the straight edges 121 is designed to be equal to the length of the minor semi-axis of the semi-elliptical arc edge 1. The semi-elliptical arc edge 1 of the groove 12 can be designed to be the same as or different from the semi-elliptical arc edge 1 of the outer periphery of the lamination body 10. By designing grooves 12 with semi-elliptical arc edges 1 at both ends of the magnet groove 101, the abruptness of magnetic flux change is reduced, effectively improving the distortion of the air gap magnetic field and back electromotive force. In addition, the semi-elliptical arc edge 1 provides a curve with continuously changing curvature. The curvature changes smoothly from the center to the edge without any abrupt change points. By reasonably controlling the size of the major and minor axes of the semi-elliptical arc edge 1, the expected eccentricity and rich contour shape can be controlled.

[0047] Furthermore, referring to Figure 7 The length of the major axis of the semi-elliptical arc side 1 is set as h1, where 1mm≤h1≤1.5mm.

[0048] In specific implementation, the major axis length of the semi-elliptical arc edge 1 determines the span of the groove 12. By reasonably constraining the size of the major axis of the semi-elliptical arc edge 1, it can have advantages in mechanical reliability and electromagnetic performance compared to a right-angled edge. In this embodiment, h1 represents the major axis length of the semi-elliptical arc edge 1. In the design, 1mm≤h1≤1.5mm, that is, the major axis length of the semi-elliptical arc edge 1 is designed within the range of 1mm~1.5mm. This design can effectively ensure the mechanical reliability and electromagnetic performance of the stamping.

[0049] Furthermore, referring to Figure 7 and Figure 8 The length of the minor semi-axis of the semi-elliptical arc side 1 is set as h2, the length of the magnet body 30 installed to the magnet groove 101 is set as t1, and the distance between the two ends of the magnet groove 101 is set as t2, wherein 0.15mm≤h2≤Min(0.3mm,t2-t1).

[0050] In specific implementation, the length of the minor semi-axis of the semi-elliptical arc 1 determines the degree of concavity of the groove 12. By reasonably constraining the size of the minor semi-axis of the semi-elliptical arc 1, it can have advantages in mechanical reliability and electromagnetic performance compared to a right-angled edge. In this embodiment, h2 represents the length of the minor semi-axis of the semi-elliptical arc 1, t1 represents the length of the magnet body 30 installed to the magnet groove 101, and t2 represents the distance between the two ends of the magnet groove 101, that is, the length of the magnet groove 101. In the design, 0.15mm≤h2≤Min(0.3mm,t2-t1), where Min(0.3mm,t2-t1) means taking the minimum value between 0.3mm and t2-t1. Designing the semi-elliptical arc through the above relationship can effectively optimize the edge of the original right-angled groove, and can effectively reduce the edge effect of the magnet, reduce harmonics and cogging torque.

[0051] Figure 9 The figure shows a comparison of the no-load back EMF waveforms of the conventional stamping scheme and the stamping scheme of this application. As can be seen from the figure, the back EMF waveform of the conventional stamping scheme has a large degree of distortion at the peaks and troughs. This waveform distortion is often caused by the large amplitude of the 5th and 7th harmonics. In contrast, the no-load back EMF waveform of the stamping scheme of this application has greatly improved the distortion at the peaks and troughs, making the overall waveform closer to a sine wave.

[0052] Figure 10 This is a bar chart comparing the total harmonic distortion (THD) parameters of the conventional back EMF and the present application's stamping scheme. THD is a quantitative indicator measuring the degree to which a signal waveform deviates from a sine wave; it represents the ratio of the total effective value of all harmonic components to the effective value of the fundamental component. Its calculation formula is as follows: , in, and These represent the fundamental frequency amplitude and the amplitude of the nth harmonic, respectively. A smaller THD value indicates that the waveform of the no-load back EMF is closer to a sine wave, and the overall harmonic component amplitude is smaller. When THD is 0, it indicates an ideal sine wave. From... Figure 10 It can be seen that the THD index of the conventional lamination scheme is 4.95%, while the THD index of the lamination scheme of this application is 2.99%, which is 39.6% lower than that of the conventional lamination scheme. This shows that the lamination scheme of this application can effectively reduce the harmonic component amplitude of the no-load back EMF and improve the stability of operation.

[0053] Figure 11 This is the instantaneous diagram of the cogging torque for a conventional lamination design. Figure 12 The instantaneous diagram of the cogging torque of the lamination design in this application is shown below. Figure 11 and Figure 12It can be seen that the peak-to-peak value of the cogging torque of the lamination scheme of this application is 725.4mN, while the peak-to-peak value of the cogging torque of the conventional lamination scheme is 1094.4mN, a decrease of nearly 33.72%. This indicates that the lamination scheme of this application can improve the magnetic field distribution, reduce the harmonic amplitude in the air gap magnetic flux density, thereby effectively reducing the cogging torque, reducing the vibration noise during motor operation, and improving the operational stability.

[0054] In summary, the rotor laminations provided in this embodiment of the invention, by setting a specific concave edge structure composed of a semi-elliptical arc edge and a symmetrical broken line edge at the corresponding position of the magnet slot on the outer periphery of the lamination, can effectively optimize the magnetic field distribution, reduce the back EMF waveform distortion and cogging torque of the permanent magnet synchronous motor, thereby reducing the final torque pulsation and vibration noise, and improving the stability of motor operation.

[0055] Reference Figure 13 The present invention also provides a rotor core 200, which includes the rotor laminations 100 described in the above embodiments. This rotor core 200 can be designed as the rotor of a permanent magnet synchronous motor. The rotor core 200 is formed by stacking a certain number of rotor laminations 100. The magnetic slots 101 on the stacked rotor laminations 100 are aligned to form a slot structure with a certain axial depth, used to install magnets 30. The magnets 30 are installed in the slots, typically with opposite polarities in adjacent slots, and each slot contains a set of magnetic poles. Since the specific structure and principle of the rotor laminations 100 have been described in detail in the above embodiments, they will not be repeated here for the sake of brevity.

[0056] The rotor core provided in this embodiment of the invention, when used in specific applications, can reduce the distortion of the back EMF waveform and the cogging torque of the permanent magnet synchronous motor, thereby reducing the final torque pulsation and vibration noise, and improving the stability of motor operation.

[0057] Furthermore, the present invention also provides an electric motor, which includes the rotor core described in the above embodiments. The motor can be composed of components such as a housing, a stator, and a rotor. The rotor is composed of the rotor core 200, a rotating shaft, and other components. Specifically, the rotor core 200 is rotatably connected to the housing via the rotating shaft. After all components are installed, the rotor core 200 is located inside the stator and coaxial with the stator. The motor generates a rotating magnetic field through the stator, causing the rotor to rotate and thus generating torque to achieve operation.

[0058] The motor provided in this embodiment of the invention uses the rotor core provided by this invention, which has lower cogging torque, a back EMF waveform that is closer to a standard sine waveform, lower vibration and noise during motor operation, and better overall performance.

[0059] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rotor lamination, characterized in that, include: The inner side of the stamp body has a number of magnetic grooves arranged in a straight line and distributed along the circumference. The outer periphery of the stamp body and the position corresponding to each magnetic groove have concave edges that are recessed toward the center of the stamp body. The concave edge is formed by connecting a semi-elliptical arc edge and two broken line edges. The minor axis of the semi-elliptical arc edge coincides with the d-axis of the motor. The two broken line edges are respectively connected to the two ends of the semi-elliptical arc edge and are symmetrical about the d-axis of the motor.

2. The rotor lamination according to claim 1, characterized in that, The broken line edge is formed by connecting the first straight line segment and the second straight line segment. The vertex of the minor axis of the semi-elliptical arc edge is connected to the outer circle of the lamination body through the first straight line segment and the second straight line segment in sequence. The first straight line segment and the second straight line segment are both inclined relative to the d-axis of the motor, and the angle between the first straight line segment and the d-axis of the motor is greater than the angle between the second straight line segment and the d-axis of the motor.

3. The rotor lamination according to claim 2, characterized in that, The angle between the two ends of the concave edge and the center of the lamination body is set as θ, where 10°≤θ≤16°.

4. The rotor lamination according to claim 3, characterized in that, The angle between the two ends of the second straight line segment and the center of the lamination body is set as α, where θ / 8≤α≤θ / 6.

5. The rotor lamination according to claim 4, characterized in that, The angle between the two ends of the first straight line and the center of the lamination body is set as β, where β = θ / 3 - α.

6. The rotor lamination according to claim 2, characterized in that, The distance from the vertex of the minor axis of the semi-elliptical arc to the outer circle of the lamination body is set as L1, and the distance from the junction of the first straight line segment and the second straight line segment to the outer circle of the lamination body is set as L2, where L2 = 1 / 2 × L1.

7. The rotor lamination according to claim 2, characterized in that, The distance from the vertex of the minor axis of the semi-elliptical arc to the outer circle of the lamination body is set as L1, and the distance from the vertex of the major axis of the first straight line segment to the outer circle of the lamination body is set as L3, where L3 = 2 / 3 × L1.

8. The rotor lamination according to any one of claims 6-7, characterized in that, 0.4mm≤L1≤0.6mm.

9. The rotor lamination according to any one of claims 1-7, characterized in that, Both ends of the magnetic steel groove are recessed towards the outer circle of the stamping body to form grooves. The outline of the groove is formed by connecting a semi-elliptical arc edge and two straight edges. The two straight edges are respectively connected to the two ends of the semi-elliptical arc edge and are parallel to the minor axis of the semi-elliptical arc edge. The length of the straight edges is equal to the length of the minor semi-axis of the semi-elliptical arc edge.

10. The rotor lamination according to claim 9, characterized in that, The length of the major axis of the semi-elliptical arc side is set as h1, where 1mm≤h1≤1.5mm.

11. The rotor lamination according to claim 9, characterized in that, The length of the minor semi-axis of the semi-elliptical arc side is set as h2, the length of the magnet body installed in the magnet groove is set as t1, and the distance between the two ends of the magnet groove is set as t2, wherein 0.15mm≤h2≤Min(0.3mm,t2-t1).

12. A rotor core, characterized in that, Includes the rotor laminations as described in any one of claims 1-11.

13. An electric motor, characterized in that, Includes the rotor core as described in claim 12.

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