Rotor core and motor having the same

Abstract

The application provides a rotor core and a motor with the same. The rotor core is formed with a plurality of magnetic poles which are arranged at intervals along the circumference of the rotor core. The outer periphery of the cross section of each magnetic pole comprises a plurality of arc lines and a plurality of straight lines, and the plurality of arc lines and the plurality of straight lines are arranged alternately. The air gap magnetic field between the stator core and the rotor core is optimized, the torque ripple is reduced, the motor demagnetization resistance and the motor efficiency are improved. The stator tooth is opposite to the magnetic pole and comprises a tooth body and a tooth shoe. The tooth shoe comprises two tooth shoes which are arranged at the two radial sides of the tooth body respectively. The tooth body corresponds to the first arc line, and the tooth shoe corresponds to the straight line. The magnetic field in the region between the tooth body and the first arc line is the strongest, the magnetic field in the region between the stator slot and the second arc line is the weakest, and the magnetic field in the region between the tooth shoe and the straight line is in the middle. The position and size of the straight line can be adjusted to adjust the magnetic field in the region. The motor iron loss is greatly reduced, the magnetic steel utilization rate is improved, and the motor harmonic loss is reduced.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, and particularly relates to a rotor core and a motor having the same. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in pure electric and hybrid new energy vehicles due to their advantages such as high torque density, high efficiency, good steady-state performance, and high reliability. Existing PMSMs are generally embedded rare-earth permanent magnet motors. Since rare-earth permanent magnet materials are scarce and expensive, effectively utilizing permanent magnet materials to design higher-performance motors is crucial for the development of electric vehicles. Furthermore, unreasonable magnet structure design and magnet slot arrangement lead to large torque ripple and weak anti-demagnetization capabilities. Summary of the Invention

[0003] In view of this, the present invention provides a rotor core and a motor having the same, to solve the problems of large torque pulsation and weak anti-demagnetization ability in the prior art.

[0004] The present invention provides a rotor core having a plurality of magnetic poles, the plurality of magnetic poles being arranged at intervals along the circumference of the rotor core; the outer periphery of the cross-section of each magnetic pole includes a plurality of arcs and a plurality of straight lines, and the plurality of arcs and the plurality of straight lines are arranged alternately.

[0005] Further optionally, the plurality of said arcs include a first arc and a second arc, the second arc comprising two; along the circumference of the rotor core, the first arc is located between the two second arcs;

[0006] The straight line includes two lines: one line connects the two adjacent endpoints of the first arc and the second arc, and the other line connects the two adjacent endpoints of the first arc and the other second arc.

[0007] Further optionally, both the first arc and the second arc are circular arcs, and the first arc and the second arc are concentrically arranged; the radius of the first arc is R1, and the radius of the second arc is R2, satisfying R1 > R2;

[0008] The straight line extends outward along the direction from the corresponding second arc to the first arc and along the radial direction of the rotor core.

[0009] Further optionally, the first arc is symmetrical about the d-axis of the magnetic pole, the two second arcs are symmetrical about the d-axis of the magnetic pole, and the two straight lines are symmetrical about the d-axis of the magnetic pole.

[0010] Further optionally, each of the magnetic poles is formed with a magnetic steel groove, the magnetic steel groove including a first groove segment and a second groove segment; the cross section of the first groove segment includes a first groove edge and a second groove edge, the first groove edge and the second groove edge are both far away from the central axis of the rotor core, and the first groove edge and the second groove edge are arranged in a V-shaped structure.

[0011] The second slot segment comprises two segments, which are located at both ends of the first slot segment and away from the central axis of the rotor core; the cross-section of each second slot segment is a polygonal structure and the polygonal structure includes a third slot side, which is adjacent to the first slot side; satisfying de1≥180°-0.5*de;

[0012] Where de is the angle between the first groove edge and the second groove edge, and de1 is the angle between the first groove edge and the third groove edge.

[0013] Alternatively, the magnet is embedded in the magnet groove, and the magnetization direction length of the magnet is H, where H≤1.5mm.

[0014] Further optionally, the polygonal structure further includes a fourth groove edge, which is adjacent to the corresponding third groove edge and close to a second arc; the fourth groove edge intersects with the extension line of the first groove edge;

[0015] The fourth slot edge and the corresponding second arc form a magnetic bridge, satisfying W≤ΔR≤0.5*H m ;

[0016] Where W is the width of the magnetic isolation bridge, and H m The width of the first groove segment is ΔR, and the radial distance between the first arc and the second arc is ΔR.

[0017] Alternatively, each of the magnetic poles may also have a noise reduction hole located between the magnetic groove and the outer periphery of the magnetic pole.

[0018] The present invention also provides an electric motor, the electric motor comprising a stator core and a rotor core as described in any of the above claims, the stator core being arranged around the outer periphery of the rotor core; the stator core having a plurality of stator teeth, the plurality of stator teeth being arranged in a one-to-one correspondence with a plurality of magnetic poles; each stator tooth comprising a tooth body and a tooth shoe, the tooth shoe comprising two tooth shoes, the two tooth shoes being respectively arranged on the radial sides of the tooth body;

[0019] The magnetic pole and the corresponding stator tooth satisfy the following: the first arc is located within the radial projection of the tooth body; one straight line is located within the radial projection of one tooth shoe and outside the radial projection of the tooth body, and the other straight line is located within the radial projection of another tooth shoe and outside the radial projection of the tooth body.

[0020] Further optionally, a stator slot is formed between two adjacent stator teeth; satisfying 0.3≤B2 / (B1+B3)≤0.1;

[0021] Wherein, the circumferential width of the tooth body is B1, the circumferential width of one tooth shoe is B2, and half of the circumferential width of the stator slot is B3.

[0022] Further optionally, each of the magnetic poles is also formed with a noise reduction hole, which is located between the magnetic steel slot of the rotor core and the outer peripheral surface of the magnetic pole, and the noise reduction hole is located within the radial projection of the tooth body.

[0023] Compared with the prior art, the main advantages of the present invention are as follows:

[0024] (1) The outer periphery of the cross section of each magnetic pole includes multiple arcs and multiple straight lines, and the multiple arcs and multiple straight lines are arranged alternately, which optimizes the air gap magnetic field between the stator core and the rotor core, improves the flow path of the demagnetizing magnetic field, and reduces torque pulsation; increases the reluctance torque component, and improves the motor's anti-demagnetizing ability and motor efficiency.

[0025] (2) The stator teeth are aligned with the magnetic poles and include a tooth body and a tooth shoe. There are two tooth shoes, which are respectively set on the radial sides of the tooth body. The tooth body corresponds to the first arc and the tooth shoe corresponds to the straight line. The magnetic field is strongest in the area between the tooth body and the first arc, weakest in the area between the stator slot and the second arc, and moderate in the area between the tooth shoe and the straight line. The magnetic field in this area can be adjusted by adjusting the position and size of the straight line. The three areas have good sinusoidal magnetic fields, which greatly reduces the iron loss of the motor, effectively reduces leakage flux, increases the magnetic focusing effect, improves the utilization rate of the magnet, and reduces the harmonic loss of the motor.

[0026] (3) Adjusting the proportion of B2 to the width of the entire magnetic pole can adjust the amplitude of the rising stage of the sinusoidal magnetic field, thereby adjusting the harmonic content of the magnetic field; the extension lines of the fourth slot side and the first slot side intersect to ensure that there is a certain air gap near the easily demagnetized areas at both ends of the magnet, bypassing part of the demagnetized magnetic field and weakening the impact of the demagnetized magnetic field; the noise reduction hole is located within the radial projection of the tooth body to reduce electromagnetic noise. Attached Figure Description

[0027] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0028] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0029] Figure 1 and Figure 2 A schematic diagram of the assembly structure of the rotor core and magnet provided by the present invention;

[0030] Figure 3 and Figure 4 A schematic diagram of the assembly structure of the rotor core, stator core, and magnet provided in this invention;

[0031] Figure 5 This is a schematic diagram of the structure of an embodiment of the motor provided by the present invention;

[0032] In the picture:

[0033] 1-Magnetic pole; 11-First arc; 12-Second arc; 13-Straight line; 14-First slot segment; 141-First slot edge; 142-Second slot edge; 15-Second slot segment; 151-Third slot edge; 152-Fourth slot edge; 16-Noise reduction hole;

[0034] 2-Magnetic steel;

[0035] 3-Stator core; 31-Stator tooth; 311-Tooth body; 312-Tooth shoe; 32-Stator slot. Detailed Implementation

[0036] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. 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.

[0037] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in the embodiments of this invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. “Multiple” generally includes at least two, but does not exclude the inclusion of at least one.

[0038] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0039] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0040] Existing permanent magnet synchronous motors (PMSMs) are widely used in pure electric and hybrid new energy vehicles due to their advantages such as high torque density, high efficiency, good steady-state performance, and high reliability. Most existing PMSMs are embedded rare-earth permanent magnet motors. Since rare-earth permanent magnet materials are scarce and expensive, effectively utilizing permanent magnet materials to design higher-performance motors is crucial for the development of electric vehicles. However, unreasonable magnet structure design and slot arrangement lead to large torque ripple and weak demagnetization resistance. Furthermore, the more magnetic poles the rotor core has, the higher the operating frequency of the motor, resulting in generally higher iron losses and severely limiting efficiency improvements. In motor technology, the air gap magnetic field is mainly concentrated within the stator region, with the magnetic field under one pole exhibiting a flat-top wave. The ideal magnetic field is a sine wave, with the strongest magnetic field directly opposite the stator teeth, decreasing along the circumference of the stator core. Therefore, it is necessary to rationally design the structure and air gap between the stator and rotor cores to reduce harmonics in the flat-top wave and achieve a sinusoidal wave-like effect.

[0041] This invention creatively provides a rotor core with multiple magnetic poles spaced circumferentially around its core. Each magnetic pole's cross-section includes multiple arcs and straight lines on its outer periphery, arranged alternately. The invention optimizes the air gap magnetic field between the stator and rotor cores, creating a unique air gap size fit, improving the flow path of the demagnetizing magnetic field, and reducing torque pulsation. It also increases the reluctance torque component, reduces higher harmonics of the magnetic field, improves the sinusoidal nature of the magnetic field, reduces iron losses, and enhances the motor's demagnetizing resistance and efficiency.

[0042] Rotor core

[0043] like Figures 1 to 4 As shown, this embodiment provides a rotor core with multiple magnetic poles 1 arranged at intervals along the circumference of the rotor core. The outer periphery of the cross-section of each magnetic pole 1 includes multiple arcs and multiple straight lines 13, which are arranged alternately. The distribution of the air gap magnetic field between the stator core and the rotor core is adjusted, the flow path of the demagnetizing magnetic field is changed, the torque pulsation is reduced, and the reluctance torque component is increased.

[0044] Furthermore, the multiple arcs include a first arc 11 and a second arc 12, with two second arcs 12; along the circumference of the rotor core, the first arc 11 is located between the two second arcs 12;

[0045] There are two straight lines 13. One straight line 13 connects the two adjacent endpoints of the first arc 11 and the second arc 12, and the other straight line 13 connects the two adjacent endpoints of the first arc 11 and the other second arc 12. Thus, along the circumference of the rotor core, the outer periphery of the cross-section of each magnetic pole 1 is sequentially provided with a second arc 12, a straight line 13, a first arc 11, another straight line 13, and another second arc 12.

[0046] Preferably, the first arc 11 and the second arc 12 are both circular arcs, and the first arc 11 and the second arc 12 are concentrically arranged; the radius of the first arc 11 is R1, and the radius of the second arc 12 is R2, satisfying R1 > R2;

[0047] The straight line 13 extends outward along the direction from the corresponding second arc 12 to the first arc 11 and along the radial direction of the rotor core.

[0048] The first arc 11 is symmetrical about the d-axis of magnetic pole 1, the two second arcs 12 are symmetrical about the d-axis of magnetic pole 1, and the two straight lines 13 are symmetrical about the d-axis of magnetic pole 1.

[0049] In addition, each magnetic pole 1 is formed with a magnetic steel groove, which includes a first groove segment 14 and a second groove segment 15. The cross-section of the first groove segment 14 includes a first groove edge 141 and a second groove edge 142. The first groove edge 141 and the second groove edge 142 are both far away from the central axis of the rotor core, and the first groove edge 141 and the second groove edge 142 are arranged in a V-shaped structure.

[0050] The second slot segment 15 includes two segments, which are located at the two ends of the first slot segment 14 and away from the central axis of the rotor core. The cross-section of each second slot segment 15 is a polygonal structure, and the polygonal structure includes a third slot side 151, which is adjacent to the first slot side 141. The condition de1≥180°-0.5*de is satisfied.

[0051] Where de is the angle between the first groove edge 141 and the second groove edge 142, and de1 is the angle between the first groove edge 141 and the third groove edge 151.

[0052] Multi-stage permanent magnet motors have a large number of magnets, which inevitably reduces the amount of magnets used in each pole and increases the leakage flux of each stage. Under such circumstances, the motor's anti-demagnetization ability and efficiency will be greatly affected. To address this, this embodiment proposes that a magnet 2 is embedded in the magnet slot, and the magnetization direction length of the magnet 2 is H, where H≤1.5mm.

[0053] Furthermore, the polygonal structure also includes a fourth groove edge 152, which is adjacent to the corresponding third groove edge 151 and close to a second arc 12; the fourth groove edge 152 intersects with the extension line of the first groove edge 141; so that there is a certain air gap near the easily demagnetized areas at both ends of the magnet, bypassing part of the demagnetizing magnetic field and weakening the impact of the demagnetizing magnetic field.

[0054] The fourth slot edge 152 and the corresponding second arc 12 form a magnetic bridge, satisfying W≤ΔR≤0.5*H. m ;

[0055] Where W is the width of the magnetic bridge, H m ΔR is the width of the first groove segment 14, and ΔR is the radial distance between the first arc 11 and the second arc 12.

[0056] <Electric motor>

[0057] like Figure 5 As shown, this embodiment also provides a motor, including a stator core 3 and a rotor core of any of the above. The stator core 3 is sleeved on the outer periphery of the rotor core. The stator core 3 is formed with a plurality of stator teeth 31, and the plurality of stator teeth 31 are arranged in a one-to-one correspondence with a plurality of magnetic poles 1. Each stator tooth 31 includes a tooth body 311 and a tooth shoe 312. There are two tooth shoes 312, and the two tooth shoes 312 are respectively arranged on the radial sides of the tooth body 311.

[0058] The magnetic pole 1 and the corresponding stator tooth 31 satisfy the following: the first arc 11 is located within the radial projection of the tooth body 311; a straight line 13 is located within the radial projection of a tooth shoe 312 and outside the radial projection of the tooth body 311; another straight line 13 is located within the radial projection of another tooth shoe 312 and outside the radial projection of the tooth body 311.

[0059] The stator teeth are aligned with the magnetic poles and include a tooth body and tooth shoes. There are two tooth shoes, which are respectively located on both radial sides of the tooth body. The tooth body corresponds to the first arc, and the tooth shoes correspond to the straight line. The magnetic field is strongest in the region between the tooth body and the first arc, weakest in the region between the stator slot and the second arc, and moderate in the region between the tooth shoes and the straight line. The magnetic field in this region can be adjusted by adjusting the position and size of the straight line. The three regions have good sinusoidal magnetic fields, which greatly reduces the iron loss of the motor, effectively reduces leakage flux, increases the magnetic focusing effect, improves the utilization rate of the magnet, and reduces the harmonic loss of the motor.

[0060] Furthermore, a stator slot 32 is formed between two adjacent stator teeth 31; satisfying 0.3≤B2 / (B1+B3)≤0.1;

[0061] The circumferential width of the tooth body 311 is B1, the circumferential width of one tooth shoe 312 is B2, and half of the circumferential width of the stator slot 32 is B3. Adjusting the proportion of B2 to the width of the entire magnetic pole can adjust the amplitude of the rising stage of the sinusoidal magnetic field, thereby adjusting the harmonic content of the magnetic field.

[0062] Along the circumference of the rotor core, from the tooth shoe to the tooth body, the radial gap between the outer periphery of the cross-section of each magnetic pole and the corresponding stator tooth gradually decreases.

[0063] In addition, each magnetic pole 1 is also formed with a noise reduction hole 16, which is located between the magnetic steel slot of the rotor core and the outer peripheral surface of the magnetic pole 1, and the noise reduction hole 16 is located within the radial projection of the tooth body 311 to reduce electromagnetic noise.

[0064] Exemplary embodiments of this disclosure have been specifically shown and described above. It should be understood that this disclosure is not limited to the detailed structures, arrangements, or implementations described herein; rather, this disclosure is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. A rotor core, characterized in that, The rotor core has multiple magnetic poles, which are spaced apart along the circumference of the rotor core. The outer periphery of the cross-section of each magnetic pole includes multiple arcs and multiple straight lines, which are arranged alternately. The multiple arcs include a first arc and a second arc, and there are two second arcs. Along the circumference of the rotor core, the first arc is located between the two second arcs. Each of the magnetic poles is formed with a magnetic steel groove, the magnetic steel groove including a first groove segment and a second groove segment; the cross-section of the first groove segment includes a first groove side and a second groove side, both of which are far from the central axis of the rotor core, and the first groove side and the second groove side are arranged in a V-shape; the second groove segment includes two segments, which are located at the two ends of the first groove segment and far from the central axis of the rotor core; the cross-section of each second groove segment is a polygonal structure, and the polygonal structure includes a third groove side and a fourth groove side; The third groove edge is arranged adjacent to the first groove edge, and satisfies de1≥180°-0.5*de; where de is the included angle between the first groove edge and the second groove edge, and de1 is the included angle between the first groove edge and the third groove edge; The fourth slot edge is adjacent to the corresponding third slot edge and close to a second arc line, and the fourth slot edge intersects with the extension line of the first slot edge; the fourth slot edge and the corresponding second arc line form a magnetic isolation bridge, and satisfy W≤ΔR≤0.5*H m Where W is the width of the magnetic bridge, and H m The width of the first groove segment is ΔR, and the radial distance between the first arc and the second arc is ΔR.

2. The rotor core according to claim 1, characterized in that, The straight line includes two lines: one line connects the two adjacent endpoints of the first arc and the second arc, and the other line connects the two adjacent endpoints of the first arc and the other second arc.

3. The rotor core according to claim 2, characterized in that, Both the first and second arcs are circular arcs, and the first and second arcs are concentric; the radius of the first arc is R1, and the radius of the second arc is R2, satisfying R1 > R2; The straight line extends outward along the direction from the corresponding second arc to the first arc and along the radial direction of the rotor core.

4. The rotor core according to claim 3, characterized in that, The first arc is symmetrical about the d-axis of the magnetic pole, the two second arcs are symmetrical about the d-axis of the magnetic pole, and the two straight lines are symmetrical about the d-axis of the magnetic pole.

5. The rotor core according to claim 1, characterized in that, The magnet is embedded in the magnet groove, and the magnetization direction length of the magnet is H, where H≤1.5mm.

6. An electric motor, characterized in that, The motor includes a stator core and a rotor core as described in any one of claims 2-5, wherein the stator core is arranged in a ring around the outer periphery of the rotor core; the stator core is formed with a plurality of stator teeth, and the plurality of stator teeth are arranged in a one-to-one correspondence with a plurality of magnetic poles; each stator tooth includes a tooth body and a tooth shoe, and the tooth shoe includes two, the two tooth shoes being respectively arranged on the radial sides of the tooth body; The first arc is located within the radial projection of the tooth body; one straight line is located within the radial projection of one tooth shoe and outside the radial projection of the tooth body, and the other straight line is located within the radial projection of the other tooth shoe and outside the radial projection of the tooth body.

7. The motor according to claim 6, characterized in that, A stator slot is formed between two adjacent stator teeth; satisfying 0.3≤B2 / (B1+B3)≤0.1; Wherein, the circumferential width of the tooth body is B1, the circumferential width of one tooth shoe is B2, and half of the circumferential width of the stator slot is B3.

8. The motor according to claim 6, characterized in that, Each of the magnetic poles is also formed with a noise reduction hole, which is located between the magnetic steel slot of the rotor core and the outer peripheral surface of the magnetic pole, and the noise reduction hole is located within the radial projection of the tooth body.

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