Rotor structure and electric motor

Abstract

Provided in the present application are a rotor structure and an electric motor. The rotor structure comprises a rotor core (11), first permanent magnets (12) and second permanent magnets (21), wherein the rotor core (11) is provided with mounting recesses, the first permanent magnets (12) are mounted in the mounting recesses, and in the axial direction of the rotor core (11), the axial height of each first permanent magnet (12) is greater than that of the rotor core (11); the second permanent magnets (21) are arranged at axial ends of the rotor core (11), each second permanent magnet (21) is of an integrated structure and is provided with a through groove (22), and at least one end of each first permanent magnet (12) protrudes from the rotor core (11) in the axial direction and is inserted into the through groove (22); and each second permanent magnet (21) further comprises an annular portion (23) and magnetic pole portions (24), and the magnetic pole portions (24) are connected by means of the annular portion (23) to form a whole. According to the rotor structure in the present application, the magnetism gathering effect of the electric motor can be effectively improved, and the comprehensive utilization rate of the permanent magnets can be increased.

Description

Rotor structure and motor

[0001] This application claims priority to the Chinese invention patent with application number "202310894327.7", application date "July 19, 2023", and invention name "Rotor structure and motor". Technical Field

[0002] The present application relates to the field of motor technology, and in particular to a rotor structure and a motor. Background Art

[0003] With the improvement of motor energy efficiency standards, higher requirements are placed on the energy efficiency level of motors. For permanent magnet motors, it is necessary to further improve the efficiency and high torque density of the motors.

[0004] At present, there are two technical means to improve the efficiency and torque density of motors. One is to embed permanent magnets to obtain a larger air gap flux density 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 deficiency 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.

[0005] Therefore, for current motors, how to further achieve higher efficiency and higher torque density is an urgent problem to be solved.

[0006] Summary of the Invention

[0007] The present application discloses a rotor structure and a motor, which can effectively improve the magnetic field concentration effect of the motor and increase the comprehensive utilization rate of permanent magnets.

[0008] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a rotor structure is provided, including a rotor core, a first permanent magnet and a second permanent magnet, the rotor core having a mounting groove, the first permanent magnet being mounted in the mounting groove, and the axial height of the first permanent magnet being greater than the axial height of the rotor core along the axial direction of the rotor core; the second permanent magnet being arranged at the axial end of the rotor core, the second permanent magnet being an integral structure and having a through slot thereon, at least one end of the first permanent magnet extending axially out of the rotor core and inserted into the through slot, the second permanent magnet also including an annular portion and a magnetic pole portion, the magnetic pole portion being formed into a whole by the connection of the annular portion.

[0009] In some embodiments, the annular portion is located radially inward of the second permanent magnet, a through slot is formed between adjacent magnetic pole portions, the magnetic pole portions are radially arranged along the circumference of the annular portion, and are connected to the annular portion through connecting ribs to form a whole with the annular portion.

[0010] In some embodiments, the rotor structure includes a through hole, which is arranged radially inward of the first permanent magnet and passes through the rotor core and the second permanent magnet.

[0011] In some embodiments, the first permanent magnet is magnetized tangentially and the second permanent magnet is magnetized axially.

[0012] In some embodiments, the second permanent magnet is an injection-molded magnetic steel.

[0013] In some embodiments, a second permanent magnet is disposed at least at one axial end portion of the rotor core.

[0014] In some embodiments, a through hole is formed between the through slot and the first permanent magnet located in the through slot.

[0015] In some embodiments, the first permanent magnet and the second permanent magnet are both magnetic flux sources, and no other magnetic conductive components are provided in the rotor structure except the rotor core.

[0016] In some embodiments, the axial height of the rotor core is x, the axial height of the first permanent magnet is y, y>x, and the axial height of the second permanent magnet is z, wherein 0.2*(yx)≤z≤1.2*(yx).

[0017] In some embodiments, z≤0.5*(yx).

[0018] In some embodiments, on a plane perpendicular to the axial direction of the rotor core, the inner diameter of the second permanent magnet is Di2, the inner diameter of the rotor core is Di1, and Di2 ≥ Di1.

[0019] In some embodiments, a limiting protrusion is provided on the outer circumferential side of the rotor core. The limiting protrusion extends laterally from both circumferential sides of the rotor core and forms a radial limit for the first permanent magnet.

[0020] In some embodiments, the outer peripheral wall of the rotor core includes a plurality of arc surfaces arranged at intervals, and along the circumferential direction, the distance between the arc surfaces and the central axis of the rotor core decreases from the middle to both ends.

[0021] In some embodiments, on a plane perpendicular to the axial direction of the rotor core, the maximum value of the outer diameter of the second permanent magnet is Do2, the maximum value of the outer diameter of the rotor core is Do1, and Do2≤Do1.

[0022] In some embodiments, Do2=Do1.

[0023] In some embodiments, one polarity region of the magnetic pole portion is arranged to correspond to one polarity region of the rotor core.

[0024] In some embodiments, a polarity region of the magnetic pole portion is adapted to a region shape of a corresponding polarity region of the rotor core, and the polarity region of the magnetic pole portion fills the corresponding polarity region of the rotor core.

[0025] In some embodiments, the second permanent magnet is injection molded ferrite or injection molded neodymium iron boron.

[0026] In some embodiments, the second permanent magnets are magnetized alternately along the axial direction of the rotor core with N and S poles.

[0027] In some embodiments, the polarity of the second permanent magnet on the side close to the rotor core is the first polarity, and the polarities of the two first permanent magnets on both sides adjacent to the second permanent magnet on the side close to the rotor core are also the first polarity.

[0028] In some embodiments, the first permanent magnet is a sintered permanent magnet or an injection molded permanent magnet.

[0029] In some embodiments, the rotor core is formed by laminating silicon steel sheets, or the rotor core is injection-molded magnetic steel, and the rotor core is magnetized alternately with N and S poles in a radial direction on a plane perpendicular to the axial direction of the rotor core.

[0030] In some embodiments, the rotor structure is filled with molding compound at the ends and the inner gap and molded into a whole.

[0031] According to another aspect of the present application, a motor is provided, comprising a stator structure and a rotor structure, wherein the rotor structure is the above-mentioned rotor structure.

[0032] The technical solution of the present application is applied to a rotor structure comprising a rotor core, a first permanent magnet, and a second permanent magnet. The rotor core has a mounting slot, the first permanent magnet being mounted within the mounting slot. Along the axial direction of the rotor core, the axial height of the first permanent magnet is greater than the axial height of the rotor core. The second permanent magnet is disposed at an axial end of the rotor core. The second permanent magnet is a monolithic structure having a through slot. At least one end of the first permanent magnet extends axially out of the rotor core and is inserted into the through slot. The second permanent magnet also includes an annular portion and a magnetic pole portion, the magnetic pole portion being connected by the annular portion to form a single unit.

[0033] The rotor structure is provided with a first permanent magnet and a second permanent magnet at the same time. The first permanent magnet and the second permanent magnet jointly provide magnetic flux for the motor, thereby increasing the torque density of the motor. The design of the relative positions of the first permanent magnet and the second permanent magnet can make the first permanent magnet serve as part of the magnetic circuit in which the magnetic flux of the second permanent magnet flows. The magnetic flux of the first permanent magnet and the second permanent magnet gather on the rotor core and then enter the air gap and the stator, thereby improving the magnetic concentration effect of the motor, effectively improving the efficiency and torque density of the motor, and increasing the output of the motor. The first permanent magnet serves as both a magnetic flux source and can draw the magnetic flux of the second permanent magnet into the rotor core. At the same time, the second permanent magnet serves as both a magnetic flux source and can block the leakage magnetic flux of the first permanent magnet, thereby achieving a higher comprehensive utilization rate of the permanent magnets. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0035] FIG1 shows a three-dimensional structural diagram of a rotor structure according to an embodiment of the present application;

[0036] FIG2 shows an exploded structural diagram of a rotor structure according to an embodiment of the present application;

[0037] FIG3 shows a side view of the rotor structure of an embodiment of the present application;

[0038] FIG4 shows a schematic diagram of the three-dimensional structure of the second permanent magnet according to an embodiment of the present application;

[0039] FIG5 shows a schematic top view of the structure of the second permanent magnet according to an embodiment of the present application;

[0040] FIG6 shows a cross-sectional view taken along the line AA in FIG5 ;

[0041] FIG7 shows a cross-sectional view taken along line BB in FIG5 ;

[0042] FIG8 shows a top view of a rotor assembly according to an embodiment of the present application;

[0043] FIG9 shows a top view of a rotor assembly according to an embodiment of the present application;

[0044] FIG10 shows a top view of the rotor structure of an embodiment of the present application;

[0045] FIG11 shows a magnetic circuit principle diagram of a rotor structure according to an embodiment of the present application;

[0046] FIG12 is a diagram showing a comparison of magnetic concentration coefficients of a motor according to an embodiment of the present application and a motor according to related art;

[0047] FIG13 is a diagram showing a comparison of the comprehensive utilization rate of permanent magnets of the motor according to the embodiment of the present application and the motor according to the related art;

[0048] FIG14 shows a comparison diagram of no-load flux linkage between the motor of the embodiment of the present application and the motor of the related art;

[0049] FIG15 shows a comparison diagram of the air gap flux density of the motor according to the embodiment of the present application and the motor according to the related art; and

[0050] FIG16 shows a comparison diagram of torque-current characteristics of the motor according to the embodiment of the present application and the motor according to the related art.

[0051] The above drawings include the following reference numerals:

[0052] 11. Rotor core; 111. Limiting protrusion; 12. First permanent magnet; 21. Second permanent magnet; 22. Through slot; 23. Annular portion; 24. Magnetic pole portion; 31. Through hole. DETAILED DESCRIPTION

[0053] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] With reference to Figures 1 to 10 , according to an embodiment of the present application, the rotor structure includes a rotor core 11, a first permanent magnet 12, and a second permanent magnet 21. The rotor core 11 has a mounting slot, and the first permanent magnet 12 is mounted in the mounting slot. Along the axial direction of the rotor core 11, the axial height of the first permanent magnet 12 is greater than the axial height of the rotor core 11. The second permanent magnet 21 is disposed at an axial end of the rotor core 11. The second permanent magnet 21 is a monolithic structure, and a through slot 22 is provided on the second permanent magnet 21. At least one end of the first permanent magnet 12 extends axially out of the rotor core 11 and is inserted into the through slot 22. The second permanent magnet 21 also includes an annular portion 23 and a magnetic pole portion 24. The magnetic pole portion 24 is formed into a single unit by connection with the annular portion 23.

[0055] A first permanent magnet 12 and a second permanent magnet 21 are simultaneously arranged in the rotor structure. The first permanent magnet 12 and the second permanent magnet 21 jointly provide magnetic flux for the motor, thereby increasing the torque density of the motor. The design of the relative positions of the first permanent magnet 12 and the second permanent magnet 21 allows the first permanent magnet 12 to serve as part of the magnetic circuit in which the magnetic flux of the second permanent magnet 21 flows. The magnetic flux of the first permanent magnet 12 and the second permanent magnet 21 gather on the rotor core 11 and then enter the air gap and the stator, thereby improving the magnetic concentration effect of the motor, effectively improving the motor efficiency and torque density, and increasing the motor output. The first permanent magnet 12 serves as a magnetic flux source and can also draw the magnetic flux of the second permanent magnet 21 into the rotor core 11. At the same time, the second permanent magnet 21 serves as a magnetic flux source and can block the leakage magnetic flux of the first permanent magnet 12, thereby achieving a higher comprehensive utilization rate of the permanent magnets.

[0056] In one embodiment, the first permanent magnet 12 is magnetized tangentially, and the second permanent magnet 21 is magnetized axially. In this embodiment, the first permanent magnet 12, which has a greater axial height, is magnetized tangentially, while the second permanent magnet 21, which is located at the axial end of the rotor core 11, is magnetized axially. This ensures that the flux linkage of the first permanent magnet 12 and the second permanent magnet 21 is continuous, allowing them to more effectively provide flux linkage for the motor, effectively increasing the motor output.

[0057] In one embodiment, the second permanent magnet 21 is an injection-molded magnet. Using injection-molded magnets can reduce rotor saturation and iron loss. In addition, injection-molded magnets have greater shape freedom, which can reduce the difficulty of manufacturing the second permanent magnet 21.

[0058] In one embodiment, the second permanent magnet 21 is injection-molded ferrite or injection-molded neodymium iron boron. The second permanent magnet 21 may also be injection-molded magnetic steel of other material types.

[0059] In one embodiment, at least one axial end of the rotor core 11 is provided with a second permanent magnet 21, so as to organize the magnetic circuit at the motor end, thereby increasing the torque density and the motor efficiency, thereby ensuring the high performance of the motor.

[0060] In one embodiment, second permanent magnets 21 are respectively provided at two axial ends of the rotor core 11 .

[0061] In one embodiment, the annular portion 23 is located radially inward of the second permanent magnet 21, and a through slot 22 is formed between each adjacent magnetic pole portion 24. The magnetic pole portion 24 is radially arranged along the circumference of the annular portion 23 and is connected to the annular portion 23 by connecting ribs, forming a whole with the annular portion 23. In order to ensure the strength of the rotor, a magnetic bridge is provided on the inner side of the rotor core 11. The annular portion 23 provided radially inward of the second permanent magnet 21 helps to saturate the magnetic bridge and reduce the leakage of the first permanent magnet 12 at the inner magnetic bridge. In this embodiment, the second permanent magnet 21 is connected to form an integral structure through the annular portion 23. That is, the second permanent magnet 21 is a whole, rather than being divided into blocks.

[0062] In one embodiment, the rotor structure is provided with a through hole 31, located radially inward of the first permanent magnet 12 and extending through the rotor core 11 and the second permanent magnet 21. The through hole 31 is formed between the through slot 22 and the first permanent magnet 12 located within the through slot 22. The through hole 31, which extends through the rotor core 11 and the second permanent magnet 21, serves as a positioning hole during rotor manufacturing. If the rotor is entirely plastic-coated, the through hole 31 can also serve as a flow channel for the plastic encapsulation compound.

[0063] In one embodiment, a support protrusion protruding radially outward is provided on the radially inner side wall of the mounting groove of the rotor core 11, and the top shape of the support protrusion matches the radially inner side wall of the first permanent magnet 12 to form surface contact.

[0064] In this embodiment, through holes 31 are formed between the sides of the support protrusion and the sidewalls of the mounting groove. The top shape of the support protrusion is adapted to the surface of the first permanent magnet 12 facing the support protrusion, enabling surface contact between the two, thereby utilizing the support protrusion to install and position the first permanent magnet 12. In this embodiment, no support protrusion is provided within the through groove 22. Instead, a U-shaped structure is formed radially inwardly of the through groove 22. The first permanent magnet 12 is restrained by the U-shaped structure, and the U-shaped structure forms the through hole 31.

[0065] In one embodiment, the first permanent magnet 12 and the second permanent magnet 21 are both magnetic flux sources, and except for the rotor core 11 , no other magnetic conductive components are provided in the rotor structure.

[0066] In one embodiment, the axial height of the rotor core 11 is x, the axial height of the first permanent magnet 12 is y, where y>x, and the axial height of the second permanent magnet 21 is z, where 0.2*(yx)≤z≤1.2*(yx). By defining the relationship between the axial heights of the rotor core 11, the first permanent magnet 12, and the second permanent magnet 21, high utilization of the rotor core 11 and permanent magnet materials can be ensured, while also minimizing magnetic flux leakage at the rotor end when the dimensions fall within this range.

[0067] In some embodiments, z ≤ 0.5*(yx) is a more optimal dimension. In this case, the magnetic flux of the second permanent magnet 21 can be completely drawn into the rotor core 11 by the first permanent magnet 12. At the same time, the second permanent magnet 21 blocks the self-leakage magnetic flux path of the first permanent magnet 12, thereby improving the overall utilization rate of the permanent magnets. Optimally, z = 0.5*(yx).

[0068] In one embodiment, in a plane perpendicular to the axial direction of the rotor core 11, the inner diameter of the second permanent magnet 21 is Di2, and the inner diameter of the rotor core 11 is Di1, where Di2 ≥ Di1. The inner hole of the rotor core 11 is required to fit a rotating shaft. This dimensional relationship allows for proper assembly of the rotating shaft. Furthermore, without compromising shaft assembly, the inner hole of the second permanent magnet 21 can be filled with plastic compound or other materials to enhance rotor strength.

[0069] In one embodiment, a limiting protrusion 111 is provided on the outer circumference of the rotor core 11 . The limiting protrusion 111 extends laterally from both circumferential sides of the rotor core 11 and forms a radial limit for the first permanent magnet 12 .

[0070] In this embodiment, the limiting protrusion 111 is located at the outermost periphery of the rotor core 11 and extends circumferentially from the two side surfaces of the rotor core 11 in the circumferential direction, and the two limiting protrusions 111 extending in opposite directions are arranged at intervals, thereby forming an open slot structure while radially limiting the first permanent magnet 12, thereby reducing the leakage magnetic field of the first permanent magnet 12 at the outer periphery of the rotor core 11.

[0071] In one embodiment, the outer peripheral wall of the rotor core 11 includes a plurality of arc surfaces arranged at intervals, and along the circumferential direction, the distance between the arc surfaces and the central axis of the rotor core 11 decreases from the middle to both ends.

[0072] In this embodiment, since the rotor core 11 forms an open slot structure, the outer peripheral structure of the rotor core 11 is not a full circle, but a plurality of arc segments arranged at intervals. The middle of each arc segment protrudes radially outward to form an arc structure that is misaligned with the center of the rotor outer circle. This can improve the air gap magnetic density between the stator and rotor, is more conducive to forming a sine curve, and improves the working performance of the motor.

[0073] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11 , the maximum value of the outer diameter of the second permanent magnet 21 is Do2 , the maximum value of the outer diameter of the rotor core 11 is Do1 , and Do2 ≤ Do1 .

[0074] In one embodiment, Do2=Do1.

[0075] For the motor, on the one hand, the stator structure is sheathed on the outside of the rotor structure, and an air gap is set between the rotor structure and the stator structure. This setting makes way for the assembly of the stator structure. On the other hand, to ensure that the first permanent magnet 12 does not fall off after being assembled into the rotor core 11, the outer circle of the rotor core 11 may be provided with a card point. The card point has a small magnetic circuit area and is easily saturated. The card point is located close to the air gap, which is the location where the magnetic flux gathers. Here, the iron loss is large. Do2≤Do1 can make the magnetic flux of the second permanent magnet 21 avoid the card point position, reducing the iron loss of the motor. In motors with a small iron loss ratio, Do2=Do1 is a better choice.

[0076] In one embodiment, one polarity region of the magnetic pole portion 24 is arranged to correspond to one polarity region of the rotor core 11 .

[0077] In one embodiment, a polar region of the magnetic pole portion 24 matches the shape of a corresponding polar region of the rotor core 11, and the polar region of the magnetic pole portion 24 completely fills the corresponding polar region of the rotor core 11. "Completely fill" here means that there is no gap between the rotor core 11 and the second permanent magnet 21 in a plane perpendicular to the axial direction of the rotor core 11.

[0078] In this embodiment, a polar region of the magnetic pole portion 24 generates magnetic flux, and a polar region of the rotor core 11 at a corresponding position is the magnetic path of the magnetic flux. The corresponding arrangement of the two can shorten the magnetic path as much as possible and reduce magnetic loss.

[0079] In one embodiment, the second permanent magnets 21 are magnetized alternately along the axial direction of the rotor core 11 with N and S poles.

[0080] In one embodiment, the polarity of the second permanent magnet 21 close to the rotor core 11 is the first polarity, and the polarities of the two first permanent magnets 12 adjacent to the second permanent magnet 21 close to the rotor core 11 are the first polarity.

[0081] In the embodiment shown in Figure 11, the second permanent magnet 21 is magnetized axially and the first permanent magnet 12 is magnetized tangentially. The magnetic lines of force of the second permanent magnet 21 enter the rotor core 11 with the part of the first permanent magnet 12 extending out of the rotor core 11 as the magnetic path, and the magnetic lines of force generated by the part of the first permanent magnet 12 inserted into the rotor core 11, after magnetization, enter the air gap and stator through the rotor core 11, which can greatly improve the magnetic concentration effect of the motor and improve the torque density and efficiency of the motor.

[0082] In one embodiment, the first permanent magnet 12 is a sintered permanent magnet or an injection-molded permanent magnet, which can be determined according to the application and operating temperature of the motor.

[0083] In one embodiment, the rotor core 11 is formed by laminating silicon steel sheets, or the rotor core 11 is injection-molded magnetic steel. In a plane perpendicular to the axial direction of the rotor core 11 , the rotor core 11 is alternately magnetized along the N and S poles in the radial direction.

[0084] The rotor core 11 is a path carrier for the flux of the first permanent magnet 12 and the second permanent magnet 21 to flow, and has the function of clearing and guiding the flux.

[0085] In one embodiment, the rotor core 11 is formed by laminating silicon steel sheets, which has better magnetic conductivity.

[0086] In one embodiment, the rotor core 11 is an injection-molded magnetic steel, which has a pulling effect on the magnetic lines of force of the first permanent magnet 12 and the second permanent magnet 21 after magnetization, and can also guide the magnetic flux to enter the air gap and the stator after concentration.

[0087] In one embodiment, the rotor structure is filled with molding compound at the ends and the internal gap and is molded into a whole, thereby ensuring the overall structural strength of the rotor assembly.

[0088] With reference to FIG12 , compared with the motor of the related art, the magnetic concentration coefficient of the motor using the rotor structure of the embodiment of the present application is increased by more than 60%, and the magnetic concentration performance is significantly improved.

[0089] 13 , compared with motors in related technologies, the motor using the rotor structure of the embodiment of the present application has a higher comprehensive utilization rate of permanent magnets, especially under heavy loads, the utilization rate of permanent magnets is increased by more than 35%.

[0090] 14 , compared with the motor in the related art, the no-load flux of the motor using the rotor structure of the embodiment of the present application is increased by more than 50%, which effectively increases the no-load flux and improves the motor performance.

[0091] 15 , compared with the motor of the related art, the air gap magnetic flux density of the motor using the rotor structure of the embodiment of the present application is increased by more than 60%, which effectively increases the air gap magnetic flux density, improves the motor torque density, and increases the motor output.

[0092] Referring to FIG16 , compared with the motors of related technologies, the torque multiple of the motor using the rotor structure of the embodiment of the present application becomes increasingly more advantageous as the current increases, thereby achieving a greater torque multiple, improving the motor torque density, and increasing the motor output.

[0093] According to an embodiment of the present application, the motor includes a stator structure and a rotor structure, and the rotor structure is the above-mentioned rotor structure.

[0094] 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 "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0095] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0096] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A rotor structure, characterized in that: The invention comprises a rotor core (11), a first permanent magnet (12) and a second permanent magnet (21); the rotor core (11) has a mounting groove, the first permanent magnet (12) is mounted in the mounting groove, and along the axial direction of the rotor core (11), the axial height of the first permanent magnet (12) is greater than the axial height of the rotor core (11); the second permanent magnet (21) is arranged at the axial end of the rotor core (11), the second permanent magnet (21) is an integral structure, and a through groove (22) is arranged thereon, at least one end of the first permanent magnet (12) extends out of the rotor core (11) along the axial direction and is inserted into the through groove (22); the second permanent magnet (21) further comprises an annular portion (23) and a magnetic pole portion (24), and the magnetic pole portion (24) is connected to form a whole by the annular portion (23).

2. The rotor structure according to claim 1, characterized in that: The annular portion (23) is located radially inward of the second permanent magnet (21), and the through groove (22) is formed between each adjacent magnetic pole portion (24). The magnetic pole portion (24) is radially arranged along the circumference of the annular portion (23) and is connected to the annular portion (23) via connecting ribs, thereby forming a whole with the annular portion (23).

3. The rotor structure according to claim 1, characterized in that: The rotor structure comprises a through hole (31), wherein the through hole (31) is arranged on the radial inner side of the first permanent magnet (12) and passes through the rotor core (11) and the second permanent magnet (21).

4. The rotor structure according to claim 1, characterized in that: The first permanent magnet (12) is magnetized tangentially, and the second permanent magnet (21) is magnetized axially.

5. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) is an injection-molded magnetic steel.

6. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) is disposed at at least one end of the axial end portion of the rotor core (11).

7. The rotor structure according to claim 1, characterized in that: A through hole (31) is formed between the through slot (22) and the first permanent magnet (12) located in the through slot (22).

8. The rotor structure according to claim 1, characterized in that: The first permanent magnet (12) and the second permanent magnet (21) are both magnetic flux sources, and except for the rotor core (11), no other magnetic conductive components are provided in the rotor structure.

9. The rotor structure according to any one of claims 1 to 8, characterized in that: The axial height of the rotor core (11) is x, the axial height of the first permanent magnet (12) is y, y>x, and the axial height of the second permanent magnet (21) is z, wherein 0.2*(yx)≤z≤1.2*(yx).

10. The rotor structure according to claim 9, characterized in that: z≤0.5*(yx).

11. The rotor structure according to any one of claims 1 to 8, characterized in that: On a plane perpendicular to the axial direction of the rotor core (11), the inner diameter of the second permanent magnet (21) is Di2, the inner diameter of the rotor core (11) is Di1, and Di2≥Di1.

12. The rotor structure according to claim 11, characterized in that: A limiting protrusion (111) is provided on the outer circumferential side of the rotor core (11), and the limiting protrusion (111) extends laterally from both circumferential sides of the rotor core (11) and forms a radial limit for the first permanent magnet (12).

13. The rotor structure according to any one of claims 1 to 8, characterized in that: The outer peripheral wall of the rotor core (11) comprises a plurality of arc surfaces arranged at intervals, and along the circumferential direction, the distance between the arc surfaces and the central axis of the rotor core (11) decreases from the middle to both ends.

14. The rotor structure according to any one of claims 1 to 8, characterized in that: On a plane perpendicular to the axial direction of the rotor core (11), the maximum value of the outer diameter of the second permanent magnet (21) is Do2, the maximum value of the outer diameter of the rotor core (11) is Do1, and Do2≤Do1.

15. The rotor structure according to claim 14, characterized in that: Do2=Do1.

16. The rotor structure according to any one of claims 1 to 8, characterized in that: A polarity region of the magnetic pole portion (24) is arranged corresponding to a polarity region of the rotor core (11).

17. The rotor structure according to claim 16, characterized in that: A polarity region of the magnetic pole portion (24) is adapted to the region shape of a corresponding polarity region of the rotor core (11), and a polarity region of the magnetic pole portion (24) fills the corresponding polarity region of the rotor core (11).

18. The rotor structure according to claim 5, characterized in that: The second permanent magnet (21) is injection-molded ferrite or injection-molded neodymium iron boron.

19. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) is magnetized alternately along the axial direction of the rotor core (11) with N and S poles.

20. The rotor structure according to claim 1 or 19, characterized in that: The polarity of the second permanent magnet (21) on the side close to the rotor core (11) is the first polarity, and the polarity of the two first permanent magnets (12) on both sides adjacent to the second permanent magnet (21) on the side close to the rotor core (11) is the first polarity.

21. The rotor structure according to claim 1, characterized in that: The first permanent magnet (12) is a sintered permanent magnet or an injection-molded permanent magnet.

22. The rotor structure according to claim 1, characterized in that: The rotor core (11) is formed by stacking silicon steel sheets, or the rotor core (11) is injection-molded magnetic steel. In a plane perpendicular to the axial direction of the rotor core (11), along the radial direction, the rotor core (11) is magnetized alternately with N and S poles.

23. The rotor structure according to claim 1, characterized in that The rotor structure is filled with molding compound at the end and the inner gap and is molded into a whole.

24. A motor, comprising a stator structure and a rotor structure, characterized in that: The rotor structure is the rotor structure according to any one of claims 1 to 23.

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