Rotor structure and motor

Abstract

The invention provides a rotor structure and a motor. The rotor structure comprises a rotor core, a first permanent magnet and a second permanent magnet, the rotor core is provided with a mounting groove, and the first permanent magnet is mounted in the mounting groove; the second permanent magnet is arranged at the axial end part of the rotor core, a groove is formed in the second permanent magnet, the first permanent magnet is partially inserted into the groove, the first permanent magnet is magnetized along the radial direction and / or tangential direction of the rotor core, the second permanent magnet is magnetized along the axial direction, and on a plane vertical to the axial direction of the rotor core, the second permanent magnet is magnetized along the radial direction and / or tangential direction of the rotor core. The length of a connecting line between the central axis of the rotor and the end edge, close to the rotating shaft side, of the second permanent magnet is Di2, the length of a connecting line between the central axis of the rotor and the center of the end edge, close to the rotating shaft side, of one pole of the first permanent magnet is Di3, and max (Di2) is larger than or equal to 0.75 * Di3. According to the rotor structure, the magnetic gathering effect of the motor can be improved, the axial end magnetic leakage of the first permanent magnet is reduced, the number of parts is small, the number of assembling steps is small, assembling is easy, and the production cost is low.

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, it is necessary to further improve the efficiency and high torque density of the motors.

[0003] 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.

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

[0005] The comparative document 201880064666.X discloses a permanent magnet rotor assembly, in which two permanent magnet sets (one set is magnetized along the circumferential direction of the rotor, and the second set provides magnetic flux along the axial direction of the rotor) generate magnetic flux gathered by the pole pieces, and there are end plates made of magnetic material. The circumferentially magnetized magnets are placed in the circumferential gap between the pole pieces, and the magnets providing axial magnetic flux are placed in the gap between the pole piece array and the end plates. The magnetic end plates in the comparative document are used to provide a return path for the magnetic flux from the magnets providing axial magnetic flux. However, in the field of home appliances, the rotor structure including multiple pole pieces, multiple scattered magnets and magnetic end plates has many parts, the magnetic end plates are difficult to fix, and the rotor assembly is difficult to assemble, resulting in high production and assembly costs, making it difficult to implement applications. Summary of the Invention

[0006] The main purpose of the present invention is to provide a rotor structure and a motor that can improve the magnetic field concentration effect of the motor and reduce the axial end magnetic leakage of the first permanent magnet, and has fewer parts, fewer assembly steps, simple assembly, and low production cost.

[0007] To achieve the above objectives, according to one aspect of the present invention, a rotor structure is provided, comprising 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 an axial end of the rotor core, the second permanent magnet being provided with a groove, the portion of the first permanent magnet extending axially out of the rotor core being inserted into the groove, the first permanent magnet being magnetized along the radial direction and / or tangential direction of the rotor core, and the second permanent magnet being magnetized along the axial direction of the rotor core, and the length of a line connecting the central axis of the rotor and any point on the inner side of the second permanent magnet close to the rotating shaft on a plane perpendicular to the axial direction of the rotor core is Di2, the length of a line connecting the central axis of the rotor and the center of the end side of one pole of the first permanent magnet close to the rotating shaft is Di3, and max(Di2)≥0.75*Di3.

[0008] Furthermore, max(Di2)≥Di3.

[0009] Furthermore, min(Di2)≥Di3.

[0010] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the length of a line connecting the central axis of the rotor and any point on the end edge of the second permanent magnet close to the rotating shaft is Di2, the inner diameter of the rotor core is Di1, and min(Di2)≥1.2*Di1.

[0011] Furthermore, a hole structure is provided on the second permanent magnet.

[0012] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the hole structure on the second permanent magnet is located close to the radial inner side of the second permanent magnet.

[0013] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the length of a line connecting the center of the hole structure and any point on the end edge of the second permanent magnet close to the rotating shaft is Di4, and the length of a line connecting the center of the hole structure and any point on the end edge of the second permanent magnet close to the air gap is Di5, min(Di4)≤min(Di5).

[0014] Furthermore, a countersunk portion is provided on the second permanent magnet, and the countersunk portion is provided on an end surface of the second permanent magnet on a side away from the rotor core.

[0015] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the countersunk portion is located radially outside the hole structure.

[0016] Furthermore, a recessed groove is provided on the second permanent magnet, and the recessed groove is provided on the end surface of the second permanent magnet on the side close to the rotor core.

[0017] Furthermore, the recessed portion is provided on the groove of the second permanent magnet.

[0018] Furthermore, the second permanent magnet is an injection-molded magnetic steel.

[0019] Furthermore, the grooves provided on the second permanent magnet do not pass through the second permanent magnet, and the number of the grooves is the same as the number of the rotor poles.

[0020] Furthermore, a protrusion is formed between adjacent grooves, and a polarity region of the protrusion corresponds to a position of a polarity region of the rotor core.

[0021] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the radial width of the second permanent magnet is c1, the radial width of the groove is c2, and the radial width of the protrusion is c3, then 0.3≤c2 / c1≤1, 0≤c3 / c1≤1.

[0022] Furthermore, the first permanent magnet and the second permanent magnet are divided into multiple polarity regions after magnetization. The first permanent magnet is magnetized with N-pole alternation along the radial direction and / or tangential direction of the rotor core; the second permanent magnet is magnetized with N-pole alternation along the axial direction of the rotor core.

[0023] Furthermore, 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.

[0024] Furthermore, the axial height of the rotor core is x, the axial height of the first permanent magnet is y, y>x, the axial height of the second permanent magnet is z1, and the axial height of the protrusion is z2, wherein 0.2*(yx)≤z1≤1.6*(yx).

[0025] Further, 0.03≤(z1-z2) / z1≤0.7.

[0026] Furthermore, the outer peripheral wall of the rotor core includes a plurality of arc surfaces arranged at intervals, and along the circumferential direction of the rotor core, the distance between a single arc surface and the central axis of the rotor core decreases from the middle to both ends.

[0027] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the length of a line connecting the center axis of the rotor and any point on the end edge of the second permanent magnet close to the air gap is Do2, and the length of a line connecting the center axis of the rotor and the center of the end edge of one pole of the first permanent magnet close to the air gap is Do3, and max(Do2)≤1.2*Do3.

[0028] Furthermore, |max(Do2)-Do3|≤1.5mm.

[0029] Furthermore, the ratio of the remanence of the second permanent magnet to the remanence of the first permanent magnet is in the range of 0.3 to 1.5.

[0030] Furthermore, the ratio of the remanence of the second permanent magnet to the remanence of the first permanent magnet is in the range of 0.5 to 0.8.

[0031] According to another aspect of the present invention, a motor is provided, comprising a stator structure and a rotor structure. The rotor structure is the above-mentioned rotor structure, and the stator structure is sleeved on the outer circumference of the rotor structure.

[0032] Furthermore, the axial height of the rotor core is x; the stator structure includes the stator core, and the axial height of the stator core is w, where x≥w.

[0033] According to the technical solution of the present invention, the rotor structure includes a rotor core, a first permanent magnet, and a second permanent magnet. The rotor core has a mounting groove, the first permanent magnet is mounted in the mounting groove, and 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 arranged at the axial end of the rotor core, and the second permanent magnet is provided with a groove, and the portion of the first permanent magnet extending axially out of the rotor core is inserted into the groove, the first permanent magnet is magnetized along the radial direction and / or tangential direction of the rotor core, and the second permanent magnet is magnetized along the axial direction of the rotor core. On a plane perpendicular to the axial direction of the rotor core, the length of a line connecting the central axis of the rotor and any point on the inner side of the second permanent magnet close to the rotating shaft is Di2, and the length of a line connecting the central axis of the rotor and the center of the end side of one pole of the first permanent magnet close to the rotating shaft is Di3, and max(Di2)≥0.75*Di3.

[0034] A first permanent magnet and a second permanent magnet are simultaneously arranged in the rotor, and the first permanent magnet and the second permanent magnet jointly provide magnetic flux for the motor, which can increase the output of the motor; the relative positions of the first permanent magnet and the second permanent magnet are designed, and the first permanent magnet is arranged to be inserted into the groove of the second permanent magnet. The first permanent magnet serves as part of the magnetic circuit for the flow of magnetic flux of the second permanent magnet, pulling the magnetic flux of the second permanent magnet into the rotor core; after the magnetic flux of the first permanent magnet and the second permanent magnet are concentrated on the rotor core, they enter the air gap and the stator, which can greatly improve the magnetic concentration effect of the rotor; in addition, except for the rotor core, no other magnetic conductive components are arranged in the rotor structure, with fewer parts, fewer assembly steps, simple assembly, and low production cost. At the same time, the axial end leakage magnetic flux of the first permanent magnet needs to pass through the second permanent magnet to form a closed loop. The second permanent magnet, which is a non-magnetic conductive component, weakens the end leakage of the first permanent magnet, and the flow direction of the magnetic flux of the second permanent magnet is opposite to the flow direction of the end leakage magnetic flux of the first permanent magnet, resulting in a mutual repulsion effect, which will further reduce the axial end leakage of the first permanent magnet and improve the magnetic field strength of the rotor. Limiting the positional relationship between the second permanent magnet and the first permanent magnet near the rotating shaft can limit the effective area of ​​the second permanent magnet's magnetic flux and the effective area of ​​the first permanent magnet's magnetic flux, weaken the repulsive force between the second permanent magnet and the first permanent magnet, and reduce the difficulty of assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0036] Figure 1 A three-dimensional structural diagram showing a rotor structure according to an embodiment of the present invention;

[0037] Figure 2 A partially exploded structural diagram showing a rotor structure according to an embodiment of the present invention;

[0038] Figure 3 An exploded structural diagram showing a rotor structure according to an embodiment of the present invention;

[0039] Figure 4 A top view of a rotor structure according to an embodiment of the present invention is shown;

[0040] Figure 5 Shown Figure 4 AA sectional view;

[0041] Figure 6 A schematic top view of a partial structure of a rotor structure according to another embodiment of the present invention is shown;

[0042] Figure 7 A schematic side view of a rotor structure according to an embodiment of the present invention is shown;

[0043] Figure 8 Shown Figure 7 BB cross-sectional view;

[0044] Figure 9 A schematic side view of the structure of a motor according to an embodiment of the present invention is shown;

[0045] Figure 10 A three-dimensional structural diagram showing a rotor structure according to another embodiment of the present invention;

[0046] Figure 11 A top view of a rotor structure according to another embodiment of the present invention is shown;

[0047] Figure 12 Shown Figure 11 CC sectional view;

[0048] Figure 13 A schematic diagram showing the three-dimensional structure of the second permanent magnet of the rotor structure according to an embodiment of the present invention is shown;

[0049] Figure 14 A top structural diagram showing a second permanent magnet of a rotor structure according to an embodiment of the present invention is shown;

[0050] Figure 15 A bottom structural diagram showing a second permanent magnet of a rotor structure according to an embodiment of the present invention is shown;

[0051] Figure 16 A schematic diagram showing the polar direction of the rotor structure of the present invention is shown;

[0052] Figure 17 A magnetic circuit principle diagram of the rotor structure of the present invention is shown;

[0053] Figure 18 A three-dimensional structural diagram showing a rotor structure according to another embodiment of the present invention;

[0054] Figure 19 It shows a three-dimensional structural diagram of the rotor structure of the present invention after being filled with plastic packaging material and plastic-sealed into a whole;

[0055] Figure 20 A comparison diagram of the magnetic concentration coefficients of the motor according to the embodiment of the present invention and the motor according to the related art is shown;

[0056] Figure 21 A comparison diagram of the magnetic flux leakage coefficients of a motor according to an embodiment of the present invention and a motor according to related art is shown;

[0057] Figure 22 A comparison diagram of no-load flux linkage between a motor according to an embodiment of the present invention and a motor in the related art is shown;

[0058] Figure 23 A comparison diagram of the air gap flux density between the motor according to the embodiment of the present invention and the motor according to the related art is shown;

[0059] Figure 24 A comparison diagram of torque-current characteristics of a motor according to an embodiment of the present invention and a motor according to related art is shown;

[0060] Figure 25 A diagram showing a comparison of torque ripple between a motor according to an embodiment of the present invention and a motor according to related art; and

[0061] Figure 26 A diagram showing the relationship between max(Di2) / Di3 and the utilization rate of the second permanent magnet, the saturation coefficient of the rotor core, and the repulsive force between the first permanent magnet and the second permanent magnet in the rotor structure of an embodiment of the present invention is shown.

[0062] The above drawings include the following reference numerals:

[0063] 11. Rotor core; 111. Limiting protrusion; 12. First permanent magnet; 21. Second permanent magnet; 211. Hole structure; 212. Identification portion; 213. Groove; 214. Protrusion; 215. Countersunk portion; 216. Sink portion; 31. Stator core. DETAILED DESCRIPTION

[0064] 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 invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0065] See also Figures 1 to 19 As shown, according to an embodiment of the present invention, 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 groove, and the first permanent magnet 12 is installed in the mounting groove. 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, and a groove 213 is provided on the second permanent magnet 21. The part of the first permanent magnet 12 that extends axially out of the rotor core 11 is inserted into the groove 213. The first permanent magnet 12 is magnetized along the radial direction and / or tangential direction of the rotor core 11, and the second permanent magnet 21 is magnetized along the axial direction of the rotor core 11.

[0066] like Figure 17As shown, a first permanent magnet 12 and a second permanent magnet 21 are simultaneously arranged in the rotor. The first permanent magnet 12 and the second permanent magnet 21 jointly provide magnetic flux for the motor, which can increase the output of the motor. The relative positions of the first permanent magnet 12 and the second permanent magnet 21 are designed and arranged so that the first permanent magnet 12 is inserted into the groove 213 of the second permanent magnet 21. The first permanent magnet 12 serves as a part of the magnetic circuit for the magnetic flux of the second permanent magnet 21, and pulls the magnetic flux of the second permanent magnet 21 into the rotor core 11. The magnetic flux of the first permanent magnet 12 and the second permanent magnet 21 are on the rotor core 11. After the magnetic field is concentrated, it enters the air gap and the stator, which can greatly improve the magnetic concentration effect of the rotor. In addition, except for the rotor core 11, no other magnetic conductive components are set in the rotor structure. The axial end leakage magnetic lines of the first permanent magnet 12 need to pass through the second permanent magnet 21 to form a closed loop. The second permanent magnet 21, which is a non-magnetic conductive component, weakens the end leakage of the first permanent magnet 12, and the flow direction of the magnetic lines of the second permanent magnet 21 is opposite to the flow direction of the end leakage magnetic lines of the first permanent magnet 12. There is a mutual repulsion effect, which will further reduce the axial end leakage of the first permanent magnet 12 and improve the rotor magnetic field strength.

[0067] The coordinated design of the first permanent magnet 12 and the second permanent magnet 21 in the rotor structure provides a return magnetic circuit for the magnetic flux of the second permanent magnet 21 through the first permanent magnet 12, and there is no need to add an additional magnetic end plate that cooperates with the magnetic circuit of the second permanent magnet 21. This can eliminate the magnetic dependence of the second permanent magnet 21 on the magnetic end plate, and at the same time reduce the number of rotor parts, resulting in fewer assembly steps, simpler assembly, and lower production costs.

[0068] In one embodiment, the first permanent magnet 12 is magnetized in the radial and / or tangential directions of the rotor core 11, and the second permanent magnet 21 is magnetized in the axial direction of the rotor core 11. Magnetic lines of force entering the rotor core 11 from different directions create a magnetic field concentration effect on the rotor core 11, thereby increasing the rotor magnetic field strength and the utilization rate of the rotor core 11.

[0069] like Figure 17 As shown, in this embodiment, the first permanent magnet 12 with a larger axial height is set to be tangentially magnetized, and the second permanent magnet 21 set at the axial end of the rotor core 11 is set to be axially magnetized, which can achieve the continuity of the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21, so that the two can more effectively provide magnetic flux for the motor together, effectively increasing the motor output.

[0070] In one embodiment, the first permanent magnet 12 is a combination of tangential magnetization and radial magnetization.

[0071] In one embodiment, the magnetization direction of the second permanent magnet 21 is not limited to being parallel to the axial direction of the rotor core 11 , but may also be at an acute angle to the axial direction of the rotor core 11 .

[0072] In one embodiment, a hole structure 211 is provided on the second permanent magnet 21. The shape of the hole structure is not limited to circular, elliptical, square or other shapes.

[0073] In one embodiment, a projection is made on one end face of the rotor core 11 along the axial direction of the rotor core 11. Within the projection plane, the shape of the hole structure 211 on the second permanent magnet 21 matches the shape of the rotor core 11 at the corresponding position. The magnetic lines of force of the second permanent magnet 21 enter the rotor core 11 after being magnetically guided by the end face of the rotor core 11 to form the main magnetic field. The shape of the hole structure 211 matches the shape of the rotor core 11 at the corresponding position to improve the assembly accuracy of the second permanent magnet 21 and the rotor core 11, allowing the second permanent magnet 21 to more effectively pass through the magnetic conduction of the rotor core 11 to form the main magnetic flux, thereby improving the utilization rate of the second permanent magnet 21 and the rotor core 11. At the same time, the reasonable design of the position and shape of the hole structure 211 can guide the magnetic field of the second permanent magnet 21, ensure the uniformity and unsaturation of the magnetic field distribution of the rotor core 11, and reduce the rotor iron loss.

[0074] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the hole structure 211 on the second permanent magnet 21 is located close to the radial inner side of the second permanent magnet 21, and the magnetic lines of force on the radial inner side of the second permanent magnet 21 are sorted and guided by the hole structure 211, thereby limiting the area of ​​action of the magnetic lines of force of the second permanent magnet 21.

[0075] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the center of the hole structure 211 and any point on the end edge of the second permanent magnet 21 near the rotating shaft is Di4, and the length of the line connecting the center of the hole structure 211 and any point on the end edge of the second permanent magnet 21 near the air gap is Di5, min(Di4)≤min(Di5), preferably, min(Di4)<min(Di5). Further restricting the position of the hole structure 211 allows it to organize and guide the magnetic lines of force of the second permanent magnet 21, thereby reducing the repulsive force of the second permanent magnet 21 on the first permanent magnet 12 and reducing the difficulty of assembly and manufacturing.

[0076] In one embodiment, a countersunk portion 215 is provided on the second permanent magnet 21, and the countersunk portion 215 is provided on the end face of the second permanent magnet 21 on the side away from the rotor core 11. On the one hand, the provision of the countersunk portion 215 can change the magnetic resistance of the magnetic flux of the second permanent magnet 21 when it passes through self-short circuit, and the air magnetic resistance at the countersunk portion 215 is increased, thereby weakening the ineffective self-short circuit magnetic flux of the second permanent magnet 21; on the other hand, the countersunk portion 215 can be used for positioning the second permanent magnet 21 during the manufacturing and assembly process, thereby simplifying the manufacturing and assembly process. In addition, the countersunk portion 215 is provided on the end face of the second permanent magnet 21 on the side away from the rotor core 11, so that the countersunk portion 215 does not affect the surface area of ​​the magnetic supply surface of the second permanent magnet 21 that directly contacts the rotor core 11, thereby maximizing the utilization of the magnetic flux of the second permanent magnet 21.

[0077] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the countersunk portion 215 is located radially outside the hole structure 211 to increase the effect of the countersunk portion 215 on the radially outer magnetic flux of the second permanent magnet 21, further weaken the self-short-circuit magnetic flux of the second permanent magnet 21, and improve the magnetic flux utilization rate of the second permanent magnet 21.

[0078] In one embodiment, the second permanent magnet 21 is provided with a recessed groove 216 on the end surface of the second permanent magnet 21 on the side closest to the rotor core 11. The recessed groove 216 can reduce the volume of the raw material used for the second permanent magnet 21 and lower the material cost of the second permanent magnet 21. Furthermore, the recessed groove 216 can be used to position the second permanent magnet 21 during the molding process, reducing the difficulty of molding the second permanent magnet 21.

[0079] In one embodiment, the recessed groove 216 is disposed on the groove 213 of the second permanent magnet 21 , so that the recessed groove 216 does not affect the area of ​​the magnetization surface of the second permanent magnet 21 .

[0080] In one embodiment, the second permanent magnet 21 is provided with an identification portion 212. The identification portion 212 is used to identify the polarity sequence of the second permanent magnet 21. The identification portion 212 is not limited to letter identification, shape identification or other forms of identification.

[0081] In one embodiment, the identification portion 212 is provided on the end surface of the second permanent magnet 21 on the side close to and / or away from the rotor core 11. Preferably, the identification portion 212 is provided on the end surface of the second permanent magnet 21 on the side close to and away from the rotor core 11, that is, the identification portion is provided on the axial end surface of both sides of the second permanent magnet 21, so as to facilitate identification of the polarity of the second permanent magnet 21.

[0082] In one embodiment, the identification portion 212 is disposed in an adjacent area of ​​a hole structure 211. The cooperation between the identification portion 212 and the hole structure 211 can ensure the uniqueness of the polarity sequence of the second permanent magnet 21 after magnetization.

[0083] In one embodiment, the number of the hole structures 211 provided on the second permanent magnet 21 is no less than 2, so as to ensure the symmetry of the rotor magnetic field and reduce torque pulsation and harmonic loss caused by magnetic field asymmetry.

[0084] In one embodiment, a rivet is embedded in the hole structure 211 , passes through the hole structure 211 on the second permanent magnet 21 , enters the rotor core 11 , extends from the other end face of the rotor assembly, and is riveted and fastened to assemble the rotor assembly.

[0085] 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 and the rotor structure.

[0086] 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.

[0087] In one embodiment, at least one of the axial ends of the rotor core 11 is provided with a second permanent magnet 21, and the number of second permanent magnets 21 provided in the rotor structure is not less than one. Preferably, the number of second permanent magnets 21 provided in the rotor structure is two, that is, second permanent magnets 21 are provided at both axial ends of the rotor core 11, so that the magnetic circuit at the end of the motor can be sorted out, so that the torque density is greater, the motor efficiency is higher, and the high performance of the motor is guaranteed. In the axial direction of the rotor core 11, the rotor core 11 and the second permanent magnet 21 are fitted together to reduce the loss of the magnetic flux of the second permanent magnet 21 during circulation. It should be noted that the single second permanent magnet 21 here refers to all second permanent magnets 21 located on a certain axial plane at the axial end of the rotor core 11. However, the single second permanent magnet 21 is not limited to an integral structure or a block structure, such as Figure 13 The second permanent magnet 21 shown is an integral structure. Figure 18 The second permanent magnet 21 shown is a block-type structure.

[0088] In one embodiment, when the single second permanent magnet 21 is a segmented structure, the number of segments is not limited to 2 or more.

[0089] In one embodiment, the second permanent magnet 21 cooperates with the first permanent magnet 12 through the groove 213 provided thereon. The first permanent magnet 12 and the second permanent magnet 21 are both magnetic flux sources. Except for the rotor core 11, no other magnetic conductive components are provided in the rotor structure.

[0090] In one embodiment, the grooves 213 provided on the second permanent magnet 21 do not penetrate the second permanent magnet 21. The number of the grooves 213 is the same as the number of the rotor poles, and a bump 214 is formed between adjacent grooves 213. The grooves 213 do not penetrate the second permanent magnet 21, so that the second permanent magnet 21 is a whole. Figure 3 As shown, in one embodiment of the present invention, a protrusion 214 is formed between two adjacent grooves, and the outer and inner sides of the two adjacent protrusions 214 are disconnected, which can reduce the processing difficulty of the second permanent magnet 21 and reduce the processing cost. In another embodiment of the present invention, a protrusion 214 is formed between two adjacent grooves 213, and the outer sides of the two adjacent protrusions 214 are disconnected, which can reduce the leakage flux at the outer circle of the rotor; in order to ensure the strength of the rotor, a magnetic bridge is provided on the inner side of the rotor core 11, and the second permanent magnet 21 connected to the inner side of the protrusion 214 helps to saturate the magnetic bridge, reducing the leakage flux of the first permanent magnet 12 at the inner magnetic bridge.

[0091] In one embodiment, one polarity region of the protrusion 214 corresponds to one polarity region of the rotor core 11. That is, one polarity region of the protrusion 214 of the second permanent magnet 21 generates magnetic flux, and one polarity region of the rotor core 11 at the corresponding position forms the magnetic path for this magnetic flux. This correspondence between the two can minimize the magnetic path and reduce magnetic losses.

[0092] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, a polar region of the projection 214 matches the shape of a corresponding polar region of the rotor core 11, and the polar region of the projection 214 completely fills the corresponding polar region of the rotor core 11. "Completely" here means that there is no gap between the projection 214 and the rotor core 11 on a plane perpendicular to the axial direction of the rotor core 11.

[0093] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the radial width of the second permanent magnet 21 is c1, the radial width of the groove 213 is c2, and the radial width of the protrusion 214 is c3, then 0.3≤c2 / c1≤1, 0≤c3 / c1≤1, that is, the groove 213 and the protrusion 214 may have radial widths that are unequal to those of the second permanent magnet 21. Appropriate radial widths of the groove and protrusion are selected according to assembly requirements and the degree of rotor saturation. If the rotor saturation is too large, a smaller c3 / c1 value may be selected; if the assembly difficulty needs to be reduced, a smaller c2 / c1 value may be selected.

[0094] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, on the outer circumference of the second permanent magnet 21 near the air gap, the tangential dimension of the groove 213 is d1, and the tangential dimension of the protrusion 214 is d2. Thus, d1 / d2 ≥ 0.2. Limiting the minimum value of d1 / d2 can reduce the saturation of the rotor core 11 and increase the magnetic flux utilization of the second permanent magnet 21.

[0095] In one embodiment, the first permanent magnet 12 and the second permanent magnet 21 are magnetized into multiple polarity regions. The first permanent magnet 12 is magnetized with alternating N-polarity along the radial direction and / or tangential direction of the rotor core 11; the second permanent magnet 21 is magnetized with alternating N-polarity along the axial direction of the rotor core 11.

[0096] 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 the two sides adjacent to the second permanent magnet 21 on the side close to the rotor core 11 is the first polarity, that is, the polarity of the second permanent magnet 21 on the side close to the rotor core 11 is the same as the polarity of the first permanent magnets 12 on the two sides adjacent to the second permanent magnet 21 on the side close to the rotor core 11. Figure 16 In the illustrated embodiment, the second permanent magnet 21 is magnetized axially, and the first permanent magnet 12 is magnetized tangentially. At a certain pole, the magnetization directions of both magnets point toward the rotor core 11. This magnetization method allows the superposition of the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21, thereby improving the no-load magnetic flux.

[0097] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the area of ​​a polar region of the second permanent magnet 21 is s1, and along the axial direction of the rotor core 11, the area of ​​the outer surface of the rotor core 11 is s2, then 0.2≤2p*s1 / s2≤2.2, where p is the number of rotor pole pairs. The second permanent magnet 21 is a magnetic flux source, and the rotor core 11 is a magnetic conductive structure. The magnetic flux of the second permanent magnet 21 passes through the rotor core 11 and the air gap in sequence and then enters the stator side, wherein the outer surface of the rotor core 11 is directly connected to the air gap. Limiting the minimum value of the magnetizing area of ​​the second permanent magnet 21 and the outer surface area of ​​the rotor core 11 can ensure that the rotor core 11 carries a certain amount of magnetic flux of the second permanent magnet 21, thereby improving the utilization rate of the rotor core 11; limiting the maximum value of the magnetizing area of ​​the second permanent magnet 21 and the outer surface area of ​​the rotor core 11 can limit the maximum magnetic flux of the second permanent magnet 21 carried by the rotor core 11, reduce the saturation degree of the rotor core 11, and reduce losses.

[0098] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the area of ​​a polar region of the rotor core 11 is s6, the area of ​​a polar region of the second permanent magnet 21 is s1, and along the axial direction of the rotor core 11, the area of ​​a polar region of the first permanent magnet 12 is s5, then 2≤(s1+s5) / s6≤10. It should be noted that s5 refers to the area of ​​the magnetic supply surface of a polar region of the first permanent magnet 12. In addition to carrying the magnetic flux of the second permanent magnet 21, the rotor core 11 also carries the magnetic flux of the first permanent magnet 12. Limiting the ratio of the sum of the magnetic supply surface areas of the first permanent magnet 12 and the second permanent magnet 21 to the axial magnetic guide surface area of ​​the rotor core 11 can improve the utilization rate of the rotor core 11 and ensure that the rotor core 11 has a suitable saturation.

[0099] In one embodiment, the axial height of the rotor core 11 is x, the axial height of the first permanent magnet 12 is y, y>x, the axial height of the second permanent magnet 21 is z1, and the axial height of the protrusion 214 is z2, where 0.2*(yx)≤z1≤1.6*(yx).

[0100] In one embodiment, 2*z2≥(yx), interference between the first permanent magnet 12 and the second permanent magnet 21 can be avoided, so that the first permanent magnet 12 and the second permanent magnet 21 can be assembled.

[0101] In one embodiment, z2=0.5*(yx), which can form an optimal fit, effectively avoid the gap between the first permanent magnet 12 and the second permanent magnet 21, and reduce magnetic loss.

[0102] In one embodiment, 0.03≤(z1−z2) / z1≤0.7, so that the portion of the groove 213 that does not penetrate the second permanent magnet 21 has a certain axial thickness ratio in the second permanent magnet 21 to ensure the structural strength of the second permanent magnet 21 .

[0103] In one embodiment, along the axial direction of the rotor core 11, the axial height of the second permanent magnet 21 is z1, the axial height of the rotor core 11 is x, and the axial height of the groove 213 is z3. Thus, 0.2 ≤ z3 / z1 ≤ 1, and 0.05 ≤ z3 / x ≤ 0.6. Limiting the z3 / z1 ratio ensures a certain axial height for the groove 213, simplifying the assembly process of the rotor components. Limiting the z3 / x ratio ensures that the magnetic flux sources have an appropriate ratio, ensuring that the rotor has an appropriate saturation level. Appropriate magnetic flux source ratios also help improve the torque linearity of the motor.

[0104] In one embodiment, in a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor's central axis and any point on the end edge of the second permanent magnet 21 closest to the rotating shaft is Di2, the inner diameter of the rotor core 11 is Di1, and min(Di2) ≥ 0.5*Di1, preferably, min(Di2) ≥ 1.2*Di1. The inner hole of the rotor core 11 requires the rotating shaft to be assembled. The above dimensional relationship not only allows for the assembly of the rotating shaft, but also allows the inner hole of the second permanent magnet 21 to be filled with plastic compound or other materials to enhance the rotor's strength without affecting the assembly of the rotating shaft.

[0105] In one embodiment, min(Di2)=0.5*Di1, that is, the inner diameter of the second permanent magnet 21 is the same as the inner diameter of the rotor core 11 , which can increase the magnetic supply surface of the second permanent magnet 21 and improve the flux linkage contribution of the second permanent magnet 21 .

[0106] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line between the central axis of the rotor and any point on the end side of the second permanent magnet 21 close to the rotating shaft is Di2, and the length of the line between the central axis of the rotor and the center of the end side of one pole of the first permanent magnet 12 close to the rotating shaft is Di3, and max(Di2)≥0.75*Di3. Preferably, max(Di2)≥Di3. Optimally, min(Di2)≥Di3. When close to the rotating shaft, on the one hand, the magnetic path area of ​​the rotor core 11 is too small and the core is easily saturated. On the other hand, the permanent magnet here has a small contribution to the torque and the utilization rate of the permanent magnet is low. As Figure 26 As shown, limiting the relationship between Di2 and Di3 can improve the utilization rate of the second permanent magnet 21, while reducing the saturation level of the rotor core 11 and reducing losses. In addition, limiting the positional relationship between the second permanent magnet and the first permanent magnet near the shaft can also limit the area of ​​action of the second permanent magnet's magnetic flux and the area of ​​action of the first permanent magnet's magnetic flux, weakening the repulsive force between the second permanent magnet and the first permanent magnet, and reducing the difficulty of assembly.

[0107] 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 .

[0108] 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 radial magnetic leakage of the first permanent magnet 12.

[0109] In one embodiment, the outer circumferential wall of rotor core 11 includes multiple spaced-apart arcuate surfaces. Along the circumferential direction, the distance between each arcuate surface and the central axis of rotor core 11 decreases from the center to the ends. This arrangement creates an air gap structure with uneven thickness along the rotor radial direction between the outer circumferential wall of rotor core 11 and the inner circumferential wall of the stator structure, reducing the harmonic content of the magnetic field, lowering motor torque ripple, and attenuating motor vibration noise.

[0110] 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.

[0111] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of a line connecting the central axis of the rotor and any point on the end edge of the second permanent magnet 21 close to the air gap side is Do2, and the length of a line connecting the central axis of the rotor and any point on the end edge of the rotor core 11 close to the air gap side is Do1, and max(Do2)≤max(Do1).

[0112] In one embodiment, max(Do2)≤0.98*max(Do1).

[0113] For the motor, on the one hand, the stator structure is sleeved on the outside of the rotor structure, and an air gap is provided between the rotor structure and the stator structure. This setting can make way for the assembly of the stator structure; on the other hand, in order to ensure that the first permanent magnet 12 will not fall off after being assembled into the rotor core 11, the outer circle of the rotor core 11 may be provided with a limiting protrusion 111. The magnetic circuit area of ​​the limiting protrusion 111 is small and easy to saturate, and the position of the limiting protrusion 111 is close to the air gap, which is the magnetic flux gathering position. The iron loss here is large. max(Do2)≤max(Do1) can make the magnetic flux of the second permanent magnet 21 avoid the position of the limiting protrusion 111, reducing the iron loss of the motor. In motors with a small iron loss ratio, max(Do2)=max(Do1) is a better choice. In motors with a large iron loss ratio, preferably, max(Do2)≤0.98*max(Do1). It should be noted that the end edge of the second permanent magnet 21 close to the air gap side is not limited to a full arc, a segmented arc, a combination of an arc and a straight line, a straight line or other shapes.

[0114] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line between the central axis of the rotor and any point on the end edge of the second permanent magnet 21 close to the air gap side is Do2, and the length of the line between the central axis of the rotor and the center of the end edge of one pole of the first permanent magnet 12 close to the air gap side is Do3, and max(Do2)≤1.2*Do3.

[0115] In one embodiment, |max(Do2)-Do3|≤1.5 mm.

[0116] Limiting the positional relationship of the first permanent magnet 12 and the second permanent magnet 21 near the air gap can enable the magnetic lines of force of the first permanent magnet 12 and the second permanent magnet 21 to have a better superposition effect near the air gap, thereby improving the air gap magnetic flux density.

[0117] 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.

[0118] In one embodiment, the intrinsic coercive force of the second permanent magnet 21 is lower than the intrinsic coercive force of the first permanent magnet 12. Compared to the second permanent magnet 21 located at the axial end of the rotor core 11, the first permanent magnet 12 is embedded in the rotor core 11 and is directly affected by the stator demagnetization field. Therefore, the higher intrinsic coercive force of the first permanent magnet 12 can enhance the motor's anti-demagnetization capability.

[0119] In one embodiment, the ratio of the remanence of the second permanent magnet 21 to the remanence of the first permanent magnet 12 is in the range of 0.3 to 1.5. Preferably, the ratio of the remanence of the second permanent magnet 21 to the remanence of the first permanent magnet 12 is in the range of 0.5 to 0.8. In an embodiment where the second permanent magnet 21 is an injection-molded magnet and the first permanent magnet 12 is a sintered magnet, the effect is better. Limiting the minimum value of the remanence ratio of the two magnetic flux sources can ensure that the magnetic flux of the second permanent magnet 21 accounts for an appropriate proportion, so that the motor has a stronger overload capacity; limiting the maximum value of the remanence ratio of the two magnetic flux sources can reduce the repulsive force between the second permanent magnet 21 and the first permanent magnet 12, thereby reducing the difficulty of assembling the rotor assembly.

[0120] 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 magnetized alternately with N and S poles along the radial direction.

[0121] 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.

[0122] In one embodiment, the rotor core 11 is formed by laminating silicon steel sheets, which has better magnetic conductivity.

[0123] In one embodiment, the rotor core 11 is an injection-molded magnetic steel, which has a pulling effect on the magnetic flux 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 magnetic concentration.

[0124] In one embodiment, the second permanent magnet 21 is injection-molded or filled on the rotor core 11 .

[0125] In one embodiment, the second permanent magnet 21 , the rotor core 11 and the first permanent magnet 12 are manufactured separately and then assembled together.

[0126] The second permanent magnet 21 and the first permanent magnet 12 can be processed and manufactured in different ways, so the manufacturing method of the rotor can be selected according to production conditions, thereby improving the flexibility of rotor structure production.

[0127] 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.

[0128] In one embodiment, the rotor structure is assembled and fixed together by fasteners. The rotor can be fixed together by gluing, riveting or other fastening methods, which can simplify the rotor production process and reduce production costs.

[0129] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of a line connecting the central axis of the rotor and any point on the end edge of the second permanent magnet 21 close to the air gap is Do2. After the rotor structure is filled with molding compound at the end and the internal gap and molded into a whole, the length of a line connecting the central axis of the rotor and any point on the end edge of the rotor structure close to the air gap is Do4. Then, max(Do2)≤min(Do4), so that the molding compound has a certain adhesion area, thereby increasing the overall strength of the rotor structure after molding.

[0130] See also Figure 20 As shown, compared with the motor in the related art, the magnetic concentration coefficient of the motor using the rotor structure of the embodiment of the present invention is increased by more than 60%, and the magnetic concentration performance is significantly improved.

[0131] See also Figure 21 As shown, compared with the motor in the related art, the magnetic flux leakage coefficient of the motor adopting the rotor structure of the embodiment of the present invention is reduced by more than 10%, which effectively reduces the magnetic leakage and improves the motor performance.

[0132] See also Figure 22 As shown, compared with the motor in the related art, the no-load flux of the motor adopting the rotor structure of the embodiment of the present invention is increased by more than 50%, which effectively increases the no-load flux and improves the motor performance.

[0133] See also Figure 23 As shown, compared with the motor in the related art, the air gap flux density of the motor using the rotor structure of the embodiment of the present invention is increased by more than 60%, which effectively increases the air gap flux density, improves the motor torque density, and increases the motor output.

[0134] See also Figure 24 As shown, compared with the motors in related technologies, the torque multiple of the motor using the rotor structure of the embodiment of the present invention becomes increasingly more advantageous as the current increases, thereby achieving a larger torque multiple, improving the motor torque density, and increasing the motor output.

[0135] See also Figure 25 As shown, compared with the motor in the related art, the torque pulsation of the motor adopting the rotor structure of the embodiment of the present invention is reduced by more than 30%, and the torque pulsation is significantly reduced, which can effectively weaken the electromagnetic vibration and noise of the motor.

[0136] According to an embodiment of the present invention, the motor includes a stator structure and a rotor structure, wherein the rotor structure is the above-mentioned rotor structure. The stator structure is sleeved on the outer circumference of the rotor structure.

[0137] In one embodiment, the axial height of the rotor core 11 is x; the stator structure includes a stator core 31, and the axial height of the stator core 31 is w, where x ≥ w. Preferably, x ≥ 1.05*w. In the present invention, the end magnetic flux of the rotor core 11 can enter the rotor core 11 through magnetic guidance to form the main magnetic flux, which does not rely on the excessive magnetic conductivity of the stator core 31 and can also increase the rotor magnetic field strength. Therefore, limiting the relationship between x and w can improve the utilization rate of the stator core 31 and reduce the degree of rotor saturation.

[0138] In one embodiment, the axial height of the rotor core 11 is x, the axial height of the stator core 31 is w, and the axial height of the second permanent magnet 21 is z1. Then, 0.2≤z1 / x≤0.8, 0.2≤z1 / w≤0.8, and 2.5≤z1 / (xw)≤10. The axial height of the second permanent magnet 21 is also one of the key parameters that determine the strength of its magnetic flux. Limiting the values ​​of z1 / x and z1 / w can, on the one hand, improve the utilization rate of the rotor and stator cores, and on the other hand, reasonably design the thickness of the second permanent magnet 21 based on the saturation level of the core to achieve optimal magnetic flux strength. In addition, the second permanent magnet 21 is disposed at the axial end of the rotor core 11. Its magnetic lines of force must pass through the magnetic circuit at the end of the rotor core 11 before entering the stator. Limiting the ratio z1 / (xw) ensures that the second permanent magnet 21 has a suitable magnetic circuit and reduces magnetic flux loss caused by magnetic resistance of the magnetic circuit.

[0139] In one embodiment, in a plane perpendicular to the axial direction of the rotor core 11, the area of ​​one polar region of the second permanent magnet 21 is s1, and along the axial direction of the rotor core 11, the area of ​​the outer surface of the rotor core 11 that extends above the stator core 31 is s3. Thus, 0.2 ≤ s1 / s3 ≤ 2.8. The second permanent magnet 21 is disposed at the axial end of the rotor core 11. Its magnetic flux must pass through the magnetic circuit at the end of the rotor core 11 before entering the stator. This limits the value of s1 / s3, ensuring that the end of the rotor core 11 has an appropriate area to carry the magnetic flux of the second permanent magnet 21, thereby improving rotor magnetic flux utilization.

[0140] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the area of ​​one polar region of the second permanent magnet 21 is s1. The stator core 31 includes multiple stator teeth, and the area of ​​one stator tooth is s4. Therefore, 0.6 ≤ s1 / s4 ≤ 5.0. Stator teeth are a critical component of the stator magnetic circuit and directly affect the magnetic reluctance on the stator during magnetic flux flow. Limiting the value of s1 / s4 ensures an appropriate level of stator tooth saturation and high stator core utilization, while also minimizing the magnetic reluctance of the stator magnetic circuit and high rotor flux utilization.

[0141] In one embodiment, the axial height of the rotor structure is v, and the axial height of the stator core 31 is w, where v≥1.4*w. Limiting the relationship between v and w can further improve the utilization of the stator core 31 while ensuring proper saturation of the stator.

[0142] 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.

[0143] 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.

[0144] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

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), wherein 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), and a groove (213) is provided on the second permanent magnet (21), and the portion of the first permanent magnet (12) extending axially out of the rotor core (11) is inserted into the groove (213), the first permanent magnet (12) is magnetized along the radial direction and / or tangential direction of the rotor core (11), and the second permanent magnet (21) is magnetized along the axial direction of the rotor core (11). On a plane perpendicular to the axial direction of the rotor core (11), the length of the line between the rotor center axis and any point on the inner side of the second permanent magnet (21) close to the rotating shaft is Di2, and the length of the line between the rotor center axis and the center of the end side of one pole of the first permanent magnet (12) close to the rotating shaft is Di3, and max(Di2)≥0.75*Di3.

2. The rotor structure according to claim 1, characterized in that: max(Di2)≥Di3.

3. The rotor structure according to claim 2, characterized in that: min(Di2)≥Di3.

4. The rotor structure according to claim 1, characterized in that: On a plane perpendicular to the axial direction of the rotor core (11), the length of a line connecting the central axis of the rotor and any point on the end edge of the second permanent magnet (21) close to the rotating shaft is Di2, the inner diameter of the rotor core (11) is Di1, and min(Di2)≥1.2*Di1.

5. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) is provided with a hole structure (211), and on a plane perpendicular to the axial direction of the rotor core (11), the hole structure (211) on the second permanent magnet (21) is located close to the radial inner side of the second permanent magnet (21).

6. The rotor structure according to claim 5, characterized in that: On a plane perpendicular to the axial direction of the rotor core (11), the length of a line between the center of the hole structure (211) and any point on the end edge of the second permanent magnet (21) close to the rotating shaft is Di4, and the length of a line between the center of the hole structure (211) and any point on the end edge of the second permanent magnet (21) close to the air gap is Di5, min(Di4)≤min(Di5).

7. The rotor structure according to claim 1, characterized in that: A countersunk portion (215) is provided on the second permanent magnet (21), and the countersunk portion (215) is provided on the end surface of the second permanent magnet (21) on a side away from the rotor core (11).

8. The rotor structure according to claim 1, characterized in that: A recessed groove (216) is provided on the second permanent magnet (21), and the recessed groove (216) is provided on the end surface of the second permanent magnet (21) on a side close to the rotor core (11).

9. The rotor structure according to claim 8, characterized in that: The sink portion (216) is arranged on the groove (213) of the second permanent magnet (21).

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

11. The rotor structure according to claim 1, characterized in that: The grooves (213) provided on the second permanent magnet (21) do not penetrate the second permanent magnet (21), and the number of the grooves (213) is the same as the number of rotor poles.

12. The rotor structure according to claim 1, characterized in that: A bulge (214) is formed between adjacent grooves (213), and a polarity region of the bulge (214) corresponds to the position of a polarity region of the rotor core (11).

13. The rotor structure according to claim 12, characterized in that: On a plane perpendicular to the axial direction of the rotor core (11), the radial width of the second permanent magnet (21) is c1, the radial width of the groove (213) is c2, and the radial width of the protrusion (214) is c3, then 0.3≤c2 / c1≤1, 0≤c3 / c1≤1.

14. The rotor structure according to claim 1, characterized in that The first permanent magnet (12) and the second permanent magnet (21) are divided into a plurality of polarity regions after magnetization, 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.

15. The rotor structure according to claim 12, 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, the axial height of the second permanent magnet (21) is z1, and the axial height of the protrusion (214) is z2, wherein 0.2*(yx)≤z1≤1.6*(yx).

16. The rotor structure according to claim 15, characterized in that: 0.03≤(z1-z2) / z1≤0.

7.

17. The rotor structure according to claim 1, 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 of the rotor core (11), the distance between a single arc surface and the central axis of the rotor core (11) decreases from the middle to both ends.

18. The rotor structure according to any one of claims 1 to 17, characterized in that: On a plane perpendicular to the axial direction of the rotor core (11), the length of a line connecting the rotor center axis and any point on the end edge of the second permanent magnet (21) close to the air gap is Do2, and the length of a line connecting the rotor center axis and the center of the end edge of one pole of the first permanent magnet (12) close to the air gap is Do3, and max(Do2)≤1.2*Do3.

19. The rotor structure according to claim 18, characterized in that |max(Do2)-Do3|≤1.5mm.

20. The rotor structure according to claim 1, characterized in that The ratio of the remanence of the second permanent magnet (21) to the remanence of the first permanent magnet (12) is in the range of 0.3 to 1.

5.

21. The rotor structure according to claim 20, characterized in that The ratio of the remanence of the second permanent magnet (21) to the remanence of the first permanent magnet (12) is in the range of 0.5 to 0.

8.

22. 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 21, and the stator structure is sleeved on the outer circumference of the rotor structure.

23. The motor according to claim 22, characterized in that The axial height of the rotor iron core (11) is x; the stator structure comprises a stator iron core (31), and the axial height of the stator iron core (31) is w, where x≥w.

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