Rotor structure and motor

Abstract

The invention provides a rotor structure and a motor. The rotor structure comprises a first rotor core (1), a second rotor core (2), a first permanent magnet (3) and a second permanent magnet (4), a mounting groove is formed in the second rotor core (2), the second permanent magnet (4) is placed in the mounting groove, and the axial height L5 of the second permanent magnet (4) is larger than the axial height L4 of the second rotor core (2) in the axial direction of the second rotor core (2). The second permanent magnet (4) extends out of the first end face of the second rotor core (2) in the axial direction, the first permanent magnet (3) is arranged at the second end of the second rotor core (2) in the axial direction and makes contact with the second end face of the second rotor core (2), and the first rotor core (1) is arranged at the end, away from the second rotor core (2), of the first permanent magnet (3) in the axial direction. According to the rotor structure, the axial end magnetic leakage condition of the permanent magnets can be improved, and the torque density of the motor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a rotor structure and a motor. Background Art

[0002] With the improvement of motor energy efficiency standards, higher requirements are placed on the energy efficiency level of motors. For permanent magnet motors, the efficiency and high torque density of the motors need to be further improved.

[0003] At present, there are two technical means to improve motor efficiency and torque density. One is to embed permanent magnets to obtain a larger air gap flux and a larger magnetic flux. However, due to the fixed rotor magnetic circuit structure, the energy efficiency improvement is limited. Another means is to use the rotor structure to increase the motor salient pole ratio and increase the motor's reluctance torque to compensate for the lack of permanent magnet torque. Its efficiency can be comparable to that of a permanent magnet motor, but it usually requires a larger rotor volume, which will make the motor torque density inferior to that of a permanent magnet motor.

[0004] Therefore, for current motors, how to further achieve higher efficiency and higher torque density is an urgent problem to be solved. Summary of the invention

[0005] The main purpose of the present invention is to provide a rotor structure and a motor, which can improve the magnetic flux leakage at the axial end of the permanent magnet and increase the torque density of the motor.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, a rotor structure is provided, comprising a first rotor core, a second rotor core, a first permanent magnet and a second permanent magnet, the second rotor core being provided with a mounting groove, the second permanent magnet being placed in the mounting groove, and along the axial direction of the second rotor core, the axial height L5 of the second permanent magnet being greater than the axial height L4 of the second rotor core, and the second permanent magnet axially extends out of the first end face of the second permanent magnet, the first permanent magnet being axially arranged at the second end face of the second rotor core and in contact with the second end face of the second rotor core, and the first rotor core being axially arranged at an end of the first permanent magnet away from the second rotor core.

[0007] Furthermore, 1.1≤L5 / L4≤1.4.

[0008] Furthermore, 1.2≤L5 / L4≤1.3.

[0009] Furthermore, the first rotor core is formed by stamping magnetic steel plates, and the second rotor core is formed by stacking silicon steel sheets.

[0010] Further, a rotor core segment is formed between two adjacent mounting grooves. The first permanent magnet includes a plurality of polar regions along the circumferential direction of the second rotor core. The polarities of the two second permanent magnets adjacent to the rotor core segment facing the rotor core segment are the first polarity, and the polarities of the polar regions of the first permanent magnet facing the rotor core segment are the first polarity.

[0011] Further, the first permanent magnet includes a plurality of polar regions along the circumferential direction. The polarities of adjacent polar regions are opposite at the same end of the first permanent magnet. The second permanent magnet is magnetized radially or tangentially.

[0012] Further, in a cross-section perpendicular to the central axis of the second rotor core, along the circumferential direction of the second rotor core, the distances from the outer edge of the second rotor core to the central axis of the second rotor core are not equal. The maximum distance from the outer edge of the second rotor core to the central axis of the second rotor core is R1, and the minimum distance is m1, where 0.95 ≤ m1 / R1 ≤ 0.99.

[0013] Further, along the axial direction of the second rotor core, one end of the second permanent magnet close to the first permanent magnet is in contact with the first permanent magnet.

[0014] Further, the first permanent magnet includes a plurality of polar regions along the circumferential direction. The area of one polar region is S2, and the magnetized area of one polar region is S1, where S1 / S2 ≥ 0.7.

[0015] Further, 0.85 ≤ S1 / S2 ≤ 1.

[0016] Further, in a cross-section perpendicular to the central axis of the second rotor core, the maximum distance from the outer edge of the first permanent magnet to the central axis of the second rotor core is R2, the maximum distance from the outer edge of the second rotor core to the central axis of the second rotor core is R1, the minimum distance from the inner edge of the second rotor core to the central axis of the second rotor core is r1, and the minimum distance from the inner edge of the first permanent magnet to the central axis of the second rotor core is r2, where r2 ≥ r1 and R2 ≤ R1.

[0017] Further, the minimum distance from the inner edge of the second permanent magnet to the central axis of the second rotor core is h1, and r2 / h1 ≤ 1.1.

[0018] Further, 0.5 < R1 / (R2 + r2) ≤ 1.

[0019] Further, 0.64 ≤ R1 / (R2 + r2) ≤ 0.88.

[0020] Further, the inner diameter of the first rotor core is r3, where r1 ≤ r3 ≤ r2.

[0021] Further, the first permanent magnet includes a plurality of polar regions in the circumferential direction. The magnetization area of one polar region is S1, and the thickness of the first permanent magnet in the axial direction of the second rotor core is L1, and S1 is inversely proportional to L1.

[0022] Further, when projected in the axial direction of the second rotor core, the projected area of the first rotor core on the axial end face of the second rotor core is greater than or equal to 90% of the projected area of the first permanent magnet on the axial end face of the second rotor core.

[0023] Further, the thickness of the first rotor core in the axial direction of the second rotor core is L2, and the thickness of the first permanent magnet in the axial direction of the first rotor core is L1, and 0.1 ≤ L2 / L1 ≤ 0.5.

[0024] According to another aspect of the present invention, there is provided a motor including a rotor structure, and the rotor structure is the above-mentioned rotor structure.

[0025] Applying the technical solution of the present invention, the rotor structure includes a first rotor core, a second rotor core, a first permanent magnet and a second permanent magnet. An installation groove is provided on the second rotor core, and the second permanent magnet is placed in the installation groove. Along the axial direction of the second rotor core, the axial height L5 of the second permanent magnet is greater than the axial height L4 of the second rotor core, and the second permanent magnet axially extends beyond the first end face of the second permanent magnet. The first permanent magnet is axially arranged on the second end face of the second rotor core and is in contact with the second end face of the second rotor core. The first rotor core is axially arranged at one end of the first permanent magnet away from the second rotor core. The assembly composed of the first permanent magnet and the first rotor core is arranged on one axial end face of the second rotor core, and the second permanent magnet is arranged to protrude above the second rotor core on the other axial end face of the second rotor core. The combined use of the magnetic circuit structures on the two axial end faces of the second rotor core improves the utilization rate of the second rotor core and increases the permanent magnetic flux without increasing the amount of silicon steel sheets. The magnetic field line direction of the first permanent magnet and the flow direction of the end leakage flux of the second permanent magnet repel each other, which can reduce the leakage flux at the axial end of the second permanent magnet close to the first permanent magnet. In addition, since there is no magnetic conduction magnetic circuit for the part of the second permanent magnet extending beyond the second rotor core to cooperate with its leakage flux, the end leakage flux of the second permanent magnet can also be greatly weakened. The magnetic circuit cooperation design of the first permanent magnet and the second permanent magnet reduces the leakage magnetic flux at both ends of the rotor, improves the torque density of the motor, and increases the output torque of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0027] Figure 1Shows a three-dimensional structure diagram of the rotor structure of an embodiment of the present invention;

[0028] Figure 2 Shows an exploded structure schematic diagram of the rotor structure of an embodiment of the present invention;

[0029] Figure 3 Shows an axial structure diagram of the rotor structure of an embodiment of the present invention;

[0030] Figure 4 Shows a dimensional structure diagram of the rotor structure of an embodiment of the present invention;

[0031] Figure 5 Shows an axial structure diagram of the first permanent magnet of the rotor structure of an embodiment of the present invention;

[0032] Figure 6 Shows an axial structure diagram of the first rotor core of the rotor structure of an embodiment of the present invention;

[0033] Figure 7 Shows a schematic diagram of the magnetization direction of the rotor structure of an embodiment of the present invention;

[0034] Figure 8 Shows a comparison diagram of the permanent magnet flux linkage between the motor of the embodiment of the present invention and the motor of the prior art; and

[0035] Figure 9 Shows a comparison diagram of the leakage magnetic coefficient between the motor of the embodiment of the present invention and the motor of the prior art.

[0036] Among them, the above-mentioned drawings include the following reference numerals:

[0037] 1. First rotor core; 2. Second rotor core; 3. First permanent magnet; 4. Second permanent magnet; 5. Installation groove. Detailed implementation manners

[0038] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0039] Combined with reference to Figures 1 to 9As shown, according to an embodiment of the present invention, the rotor structure includes a first rotor core 1, a second rotor core 2, a first permanent magnet 3 and a second permanent magnet 4. The second rotor core 2 is provided with a mounting groove 5, and the second permanent magnet 4 is placed in the mounting groove 5. Along the axial direction of the second rotor core 2, the axial height L5 of the second permanent magnet 4 is greater than the axial height L4 of the second rotor core 2, and the second permanent magnet 4 extends axially out of the first end face A of the second rotor core 2. The first permanent magnet 3 is axially arranged on the second end face B of the second rotor core 2 and contacts the second end face B of the second rotor core 2. The first rotor core 1 is axially arranged at an end of the first permanent magnet 3 away from the second rotor core 2.

[0040] The assembly composed of the first permanent magnet 3 and the first rotor core 1 is arranged on one axial end face of the second rotor core 2, and the second permanent magnet 4 is arranged on the other axial end face of the second rotor core 2 to be higher than the second rotor core 2. The coordinated use of the magnetic circuit structures of the two axial end faces of the second rotor core 2 improves the utilization rate of the second rotor core 2, and improves the permanent magnetic flux without increasing the amount of silicon steel sheets. The magnetic force lines of the first permanent magnet 3 and the flow direction of the leakage flux at the end of the second permanent magnet 4 repel each other, which can reduce the leakage flux at the axial end of the second permanent magnet 4 close to the first permanent magnet 3. In addition, the part of the second permanent magnet 4 extending out of the second rotor core 2 has no magnetic conductive magnetic circuit to cooperate with its leakage flux, which can also greatly weaken the end leakage flux of the second permanent magnet 4. The magnetic circuit coordination design of the first permanent magnet 3 and the second permanent magnet 4 reduces the leakage flux at the two end faces of the rotor, improves the torque density of the motor, and improves the output torque of the motor.

[0041] In this embodiment, a first permanent magnet 3 is arranged at one end of the second rotor core 2, and a second permanent magnet 4 arranged in a mounting groove 5 of the second rotor core 2 extends axially out of the second rotor core 2 at an end away from the first permanent magnet 3. This can reduce the difficulty of assembly and reduce costs on the basis of improving the utilization rate of the permanent magnets, while ensuring the utilization efficiency of the second rotor core 2 and effectively reducing the magnetic leakage at both ends of the second permanent magnet 4.

[0042] In one embodiment, 1.1≤L5 / L4≤1.4. When defining the relationship between the axial height of the second permanent magnet 4 and the axial height of the second rotor core 2, it is necessary to consider the influence of the axial heights of the two on the end surface magnetic leakage of the second permanent magnet 4 and the utilization efficiency of the second permanent magnet 4. When the axial height of the second permanent magnet 4 is too small, a large amount of magnetic flux will still pass through the second end magnetic leakage of the second rotor core 2 at the second end of the second permanent magnet 4, and the purpose of weakening the end magnetic leakage will not be achieved; when the axial height of the second permanent magnet 4 is too high, the distance between the second permanent magnet 4 and the second rotor core 2 will be too large, or the magnetic circuit in the second rotor core 2 will be easily oversaturated, resulting in a reduction in the utilization rate of the second permanent magnet 4.

[0043] The relationship between the axial height of the second permanent magnet 4 and the axial height of the second rotor core 2 is defined as 1.1 ≤ L5 / L4 ≤ 1.4, which can keep the relationship between their axial heights within a suitable range, ensuring both a relatively high utilization rate of the second permanent magnet 4 and effectively reducing the end leakage magnetic flux of the second permanent magnet 4 at the second end of the second rotor core 2 far from the first permanent magnet 3, thereby improving the power density and output torque of the motor.

[0044] In one embodiment, 1.2 ≤ L5 / L4 ≤ 1.3.

[0045] Combined with reference to Figure 9 As shown, it is a comparison chart of the leakage magnetic coefficient between the motor of the embodiment of the present invention and the motor of the prior art. It can be seen from the figure that when 1.1 ≤ L5 / L4 ≤ 1.4, the leakage magnetic coefficient is significantly reduced. After L5 / L4 > 1.4, the leakage magnetic coefficient basically remains stable. Therefore, continuously increasing the axial height of the second permanent magnet 4 cannot bring about an improvement in the leakage magnetic coefficient, but will cause waste of the second permanent magnet 4. When 1.2 ≤ L5 / L4 ≤ 1.3, the improvement of the leakage magnetic coefficient of the second permanent magnet 4 compared to the prior art is the most obvious, and the utilization rate of the second permanent magnet is the highest.

[0046] In one embodiment, the first rotor core 1 is formed by stamping a magnetic conductive steel plate, and the second rotor core 2 is formed by laminating silicon steel sheets.

[0047] Using a magnetic conductive material for the first rotor core 1 can provide a magnetic path for the magnetic force lines of the first permanent magnet 3, increasing the permanent magnetic flux linkage. The thickness of the first rotor core 1 is relatively thin compared to that of the second rotor core 2, and a magnetic conductive steel plate can be directly used without using silicon steel sheets for lamination to reduce eddy current loss. This not only reduces the process flow but also saves costs.

[0048] In one embodiment, rotor core segments are formed between two adjacent mounting grooves 5. The first permanent magnet 3 includes a plurality of polarity regions along the circumferential direction of the second rotor core 2. The polarities of the two second permanent magnets 4 adjacent to the rotor core segment facing the rotor core segment are the first polarity, and the polarity of the polarity region of the first permanent magnet 3 facing the rotor core segment is the first polarity.

[0049] In this embodiment, since the polarities of the two first permanent magnets 3 and the second permanent magnets 4 facing the same rotor core segment are the same, the magnetic fluxes of the first permanent magnets 3 and the two second permanent magnets 4 can be made to squeeze towards the rotor core segment together and travel from the rotor core segment towards the stator core side, improving the magnetic flux concentration effect of the rotor structure. The polarities of the two second permanent magnets 4 are the same as those of the first permanent magnets 3, which can inhibit the magnetic force lines of the two second permanent magnets 4 traveling towards the first permanent magnets 3, effectively avoiding magnetic flux leakage at the end faces of the two second permanent magnets 4 and improving the utilization rate of the first permanent magnets 3.

[0050] By restricting the polarity relationship between the first permanent magnets 3 and the second permanent magnets 4, magnetic flux parallel connection can be formed, increasing the magnetic flux density of the main magnetic circuit and reducing the magnetic flux leakage on the side of the second permanent magnets 4 close to the first permanent magnets 3.

[0051] In one embodiment, the first permanent magnets 3 include a plurality of polar regions in the circumferential direction, and the polarities of adjacent polar regions are opposite at the same end of the first permanent magnets 3, and the second permanent magnets 4 are magnetized radially or tangentially.

[0052] In this embodiment, the first permanent magnets 3 are magnetized with alternating NS poles along the axial direction of the second rotor core 2, which means that among the polar regions arranged in sequence along the circumferential direction of the first permanent magnets 3, for two adjacent polar regions, the polarity of one polar region facing one end of the second rotor core 2 is N pole, and the polarity facing away from the second rotor core is S pole, and the polarity of the other polar region facing one end of the second rotor core 2 is S pole, and the polarity facing away from the second rotor core is N pole. Thus, magnetizing with alternating polar regions makes the magnetizing directions of adjacent polar regions opposite.

[0053] In one embodiment, in the cross-section perpendicular to the central axis of the second rotor core 2, along the circumferential direction of the second rotor core 2, the distances from the outer edge of the second rotor core 2 to the central axis of the second rotor core 2 are not equal. The maximum distance from the outer edge of the second rotor core 2 to the central axis of the second rotor core 2 is R1, and the minimum distance is m1, and 0.95 ≤ m1 / R1 ≤ 0.99.

[0054] An uneven air gap is formed between the second rotor core 2 and the stator inner diameter, which can weaken the harmonics of the air gap magnetic flux density and make the sinusoidality of the air gap magnetic flux density higher. Restricting the ratio range of the minimum value to the maximum value of the outer diameter of the second rotor core 2 can achieve the optimal effect of reducing the harmonic content and the cogging torque.

[0055] In this embodiment, the outer edge of the second rotor core 2 includes a plurality of arc edges arranged at intervals in the circumferential direction, where the centers of the arc edges are offset from the central axis of the second rotor core 2, and the radius of the arc edges is smaller than the maximum distance R1 from the outer edge of the second rotor core 2 to the central axis of the second rotor core 2.

[0056] In one embodiment, along the axial direction of the second rotor core 2, one end of the second permanent magnet 4 close to the first permanent magnet 3 is in contact with the first permanent magnet 3.

[0057] Restricting the axial contact between the second permanent magnet 4 and the first permanent magnet 3 can weaken the end leakage magnetic flux of the second permanent magnet 4 and improve the utilization rate of the first permanent magnet 3 and the second permanent magnet 4.

[0058] In one embodiment, the first permanent magnet 3 includes a plurality of polar regions in the circumferential direction. The area of one polar region is S2, and the magnetized area of one polar region is S1, where S1 / S2≥0.7.

[0059] In one embodiment, 0.85≤S1 / S2≤1.

[0060] By restricting the magnetized area of the first permanent magnet 3, the magnetic flux of one polar region of the first permanent magnet 3 can be reduced, thereby preventing the oversaturation of the motor.

[0061] In one embodiment, in a cross-section perpendicular to the central axis of the second rotor core 2, the maximum distance between the outer edge of the first permanent magnet 3 and the central axis of the second rotor core 2 is R2, the maximum distance between the outer edge of the second rotor core 2 and the central axis of the second rotor core 2 is R1, the minimum distance between the inner edge of the second rotor core 2 and the central axis of the second rotor core 2 is r1, and the minimum distance between the inner edge of the first permanent magnet 3 and the central axis of the second rotor core 2 is r2, where r2≥r1 and R2≤R1.

[0062] When the first permanent magnet 3 is annular, R2 is the outer diameter of the first permanent magnet 3, and r2 is the inner diameter of the first permanent magnet 3.

[0063] Restricting the maximum distance between the outer edge of the first permanent magnet 3 and the central axis of the second rotor core 2 to not exceed the maximum distance between the outer edge of the second rotor core 2 and the central axis of the second rotor core 2 can avoid the friction between the first permanent magnet 3 and the stator due to too small an air gap during operation and avoid unnecessary mechanical losses.

[0064] In one embodiment, the minimum distance between the inner edge of the second permanent magnet 4 and the central axis of the second rotor core 2 is h1, and r2 / h1≤1.1.

[0065] Restricting the minimum distance r1 between the inner edge of the first permanent magnet 3 and the central axis of the second rotor core 2 to radially exceed the range of the second permanent magnet 4 can avoid the waste caused by the lack of sufficient magnetic circuit in the part of the first permanent magnet 3 close to the rotating shaft side, improve the utilization rate of the first permanent magnet 3, and further improve the torque density of the motor.

[0066] In one embodiment, 0.5 < R1 / (R2 + r2) ≤ 1. The purpose of such a setting is to limit the radial position of the first permanent magnet 3 on the axial end face of the second rotor core 2, so as to ensure that the radial center of the first permanent magnet 3 is in a suitable position, which can increase its contribution to the no-load magnetic flux linkage.

[0067] In one embodiment, 0.65 ≤ R1 / (R2 + r2) ≤ 0.88, which can ensure that the outer diameter and inner diameter dimensions of the first permanent magnet 3 are appropriate, and the radial width dimension is appropriate, neither too large nor too small, which can not only achieve an effective magnetic leakage prevention effect on the second permanent magnet 4, but also provide sufficient magnetic flux to increase the contribution of the first permanent magnet 3 to the no-load magnetic flux linkage.

[0068] In one embodiment, the inner diameter of the first rotor core 1 is r3, and r1 ≤ r3 ≤ r2.

[0069] In one embodiment, r3 = r1, where r2 is the inner diameter of the first permanent magnet 3 and r1 is the inner diameter of the second rotor core 2. Limiting the inner diameter of the first rotor core 1 between the second rotor core 2 and the first permanent magnet 3 can ensure the continuity of the magnetic circuit. Under the optimal conditions, it can reduce the assembly difficulty, improve the mechanical strength of the rotor, and increase the permanent magnet magnetic flux linkage.

[0070] In one embodiment, the first permanent magnet 3 includes a plurality of polar regions in the circumferential direction. The magnetized area of one polar region is S1, and the thickness of the first permanent magnet 3 in the axial direction of the second rotor core 2 is L1. S1 is inversely proportional to L1.

[0071] Limiting the magnetized area of the first permanent magnet 3 to be inversely proportional to the axial thickness can prevent the motor from being oversaturated and causing a decrease in the motor efficiency.

[0072] In one embodiment, when projected in the axial direction of the second rotor core 2, the projected area of the first rotor core 1 on the axial end face of the second rotor core 2 is greater than or equal to 90% of the projected area of the first permanent magnet 3 on the axial end face of the second rotor core 2. Limiting the areas of the first permanent magnet 3 and the first rotor core 1 can ensure the utilization rate of the first permanent magnet 3, provide an effective magnetic circuit for the magnetic lines of force generated by the first permanent magnet 3, and increase the permanent magnet magnetic flux linkage.

[0073] In one embodiment, the thickness of the first rotor core 1 in the axial direction of the second rotor core 2 is L2, and the thickness of the first permanent magnet 3 in the axial direction of the first rotor core 1 is L1, and 0.1 ≤ L2 / L1 ≤ 0.5.

[0074] Limiting the ratio of the axial thickness of the first rotor core 1 to the axial thickness of the first permanent magnet 3 can increase the utilization rate of the first permanent magnet 3 and improve the motor torque density.

[0075] Refer to in combinationFigure 8 As shown, for the motor adopting the rotor structure of the embodiment of the present invention, the no-load magnetic flux is increased by more than 20% compared with the maximum value of the no-load magnetic flux of the motor in the prior art. Therefore, the no-load magnetic flux of the motor can be greatly improved, and the output torque of the motor can be increased.

[0076] According to the embodiment of the present invention, the motor includes a rotor structure, and this rotor structure is the above-mentioned rotor structure.

[0077] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0078] It should be noted that the terms "first", "second", etc. in the description, claims and drawings of the present 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 under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0079] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A rotor structure, characterized in that, it includes a first rotor core (1), a second rotor core (2), a first permanent magnet (3) and a second permanent magnet (4). An installation groove (5) is provided on the second rotor core (2), and the second permanent magnet (4) is placed in the installation groove (5). Along the axial direction of the second rotor core (2), the axial height L5 of the second permanent magnet (4) is greater than the axial height L4 of the second rotor core (2), and the second permanent magnet (4) axially extends out of the first end face of the second rotor core (2). The first permanent magnet (3) is axially arranged on the second end face of the second rotor core (2) and contacts the second end face of the second rotor core (2). The first rotor core (1) is axially arranged at one end of the first permanent magnet (3) away from the second rotor core (2).

2. The rotor structure according to claim 1, characterized in that, 1.1 ≤ L5 / L4 ≤ 1.

4.

3. The rotor structure according to claim 2, characterized in that, 1.2 ≤ L5 / L4 ≤ 1.

3.

4. The rotor structure according to claim 1, characterized in that, the first rotor core (1) is formed by stamping a magnetic conductive steel plate, and the second rotor core (2) is formed by laminating silicon steel sheets.

5. The rotor structure according to claim 1, characterized in that, a rotor core lobe is formed between two adjacent installation grooves (5). The first permanent magnet (3) includes a plurality of polar regions along the circumferential direction of the second rotor core (2). The polarities of the two second permanent magnets (4) adjacent to the rotor core lobe facing the rotor core lobe are the first polarity, and the polarity of the polar region of the first permanent magnet (3) facing the rotor core lobe is the first polarity.

6. The rotor structure according to claim 1, characterized in that, the first permanent magnet (3) includes a plurality of polar regions in the circumferential direction. The polarities of adjacent polar regions are opposite at the same end of the first permanent magnet (3). The second permanent magnet (4) is magnetized radially or tangentially.

7. The rotor structure according to claim 1, characterized in that, in a cross-section perpendicular to the central axis of the second rotor core (2), along the circumferential direction of the second rotor core (2), the distances from the outer edge of the second rotor core (2) to the central axis of the second rotor core (2) are not equal. The maximum distance from the outer edge of the second rotor core (2) to the central axis of the second rotor core (2) is R1, and the minimum distance is m1, 0.95 ≤ m1 / R1 ≤ 0.

99.

8. The rotor structure according to claim 1, characterized in that, along the axial direction of the second rotor core (2), one end of the second permanent magnet (4) close to the first permanent magnet (3) contacts the first permanent magnet (3).

9. The rotor structure according to claim 1, characterized in that, the first permanent magnet (3) includes a plurality of polar regions in the circumferential direction. The area of one polar region is S2, and the magnetized area of one polar region is S1, S1 / S2 ≥ 0.

7.

10. The rotor structure according to claim 9, characterized in that, 0.85 ≤ S1 / S2 ≤ 1.

11. The rotor structure according to claim 1, characterized in that, In a cross-section perpendicular to the central axis of the second rotor core (2), the maximum distance between the outer edge of the first permanent magnet (3) and the central axis of the second rotor core (2) is R2, the maximum distance between the outer edge of the second rotor core (2) and the central axis of the second rotor core (2) is R1, the minimum distance between the inner edge of the second rotor core (2) and the central axis of the second rotor core (2) is r1, the minimum distance between the inner edge of the first permanent magnet (3) and the central axis of the second rotor core (2) is r2, r2 ≥ r1, R2 ≤ R1.

12. The rotor structure according to claim 11, characterized in that, The minimum distance between the inner edge of the second permanent magnet (4) and the central axis of the second rotor core (2) is h1, and r2 / h1 ≤ 1.

1.

13. The rotor structure according to claim 11, characterized in that, 0.5 < R1 / (R2 + r2) ≤ 1.

14. The rotor structure according to claim 13, characterized in that, 0.64 ≤ R1 / (R2 + r2) ≤ 0.

88.

15. The rotor structure according to claim 1, characterized in that, The inner diameter of the first rotor core (1) is r3, and r1 ≤ r3 ≤ r2.

16. The rotor structure according to claim 1, characterized in that, The first permanent magnet (3) includes a plurality of polar regions in the circumferential direction. The magnetized area of one polar region is S1, and the thickness of the first permanent magnet (3) in the axial direction of the second rotor core (2) is L1. S1 is inversely proportional to L1.

17. The rotor structure according to claim 1, characterized in that, When projected in the axial direction of the second rotor core (2), the projected area of the first rotor core (1) on the axial end face of the second rotor core (2) is greater than or equal to 90% of the projected area of the first permanent magnet (3) on the axial end face of the second rotor core (2).

18. The rotor structure according to claim 1, characterized in that, The thickness of the first rotor core (1) in the axial direction of the second rotor core (2) is L2, and the thickness of the first permanent magnet (3) in the axial direction of the first rotor core (1) is L1. 0.1 ≤ L2 / L1 ≤ 0.

5.

19. A motor, comprising a rotor structure, characterized in that, The rotor structure is the rotor structure according to any one of claims 1 to 18.

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