Rotor assembly, motor and vehicle

Abstract

The present invention discloses a rotor assembly, a motor and a vehicle, wherein the rotor assembly comprises: a rotor core, wherein the rotor core is provided with a plurality of first mounting grooves, wherein the plurality of first mounting grooves are arranged at intervals along the circumference of the rotor core, wherein each of the first mounting grooves is provided with a first magnet group; wherein the first magnet group comprises a first permanent magnet, a second permanent magnet and a third permanent magnet, wherein the first permanent magnet and the third permanent magnet are located on both sides of the second permanent magnet, wherein the remanence of the second permanent magnet is higher than the remanence of the first permanent magnet and the third permanent magnet, and the material of the second permanent magnet is different from the material of the first permanent magnet and the third permanent magnet. Thus, the cogging torque generated by the rotor assembly during rotation can be reduced, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter problem caused by the unstable output caused by the torque fluctuation, and being beneficial to improving the NVH performance, and reducing the risk of demagnetization of the rare earth magnet steel.

Description

Technical Field

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

[0002] Permanent magnet synchronous motors are widely used in electric vehicles. The motor is one of the cores of the electric drive system, and the comprehensive performance of the motor directly affects the performance of electric vehicles. At present, there are still technical bottlenecks in the development of high overload capacity and anti-demagnetization permanent magnet synchronous motors (PMSM) for electric vehicles. There are a series of problems such as large cogging torque, high cost, and poor load torque, and there is room for improvement. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a rotor assembly that can reduce the cogging torque generated during the rotation process, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter problem caused by the unstable output caused by the torque fluctuation, and is conducive to improving the NVH performance.

[0004] According to an embodiment of the present invention, a rotor assembly includes: a rotor core, the rotor core is provided with a plurality of first mounting grooves, the plurality of first mounting grooves are arranged at intervals along the circumference of the rotor core, a first magnet group is arranged in each first mounting groove; the first magnet group includes a first permanent magnet, a second permanent magnet and a third permanent magnet, the first permanent magnet and the third permanent magnet are located on both sides of the second permanent magnet, the remanence of the second permanent magnet is higher than the remanence of the first permanent magnet, the remanence of the second permanent magnet is higher than the remanence of the third permanent magnet, and the material of the second permanent magnet is different from the material of the first permanent magnet and the third permanent magnet.

[0005] According to the rotor assembly of an embodiment of the present invention, a first magnet group is provided in the first mounting groove of the rotor core, and the first magnet group is provided to include a first permanent magnet, a second permanent magnet and a third permanent magnet arranged in sequence, thereby reducing the cogging torque generated by the rotor assembly during rotation, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter caused by the torque fluctuation, and helping to improve the NVH performance. In addition, by setting the remanence of the second permanent magnet to be higher than the remanence of the first permanent magnet and the third permanent magnet, for example, setting the first permanent magnet and the third permanent magnet to be ferrite magnets, such a setting reduces the amount of rare earth magnets in the rotor assembly, reduces the cost of the rotor assembly, and allows the ferrite magnets to protect the rare earth magnets to reduce the risk of demagnetization of the rare earth magnets.

[0006] According to some embodiments of the rotor assembly of the present invention, the rotor core is further provided with a plurality of second mounting grooves, the plurality of first mounting grooves and the plurality of second mounting grooves are alternately arranged along the circumferential direction of the rotor core, a second magnet group is arranged in each of the second mounting grooves, the second magnet group includes a fourth permanent magnet, a fifth permanent magnet and a sixth permanent magnet, the fourth permanent magnet and the sixth permanent magnet are located on both sides of the fifth permanent magnet, the residual magnetism of the fifth permanent magnet is higher than the residual magnetism of the fourth permanent magnet, the residual magnetism of the fifth permanent magnet is higher than the residual magnetism of the sixth permanent magnet, and the material of the fifth permanent magnet is different from the materials of the fourth permanent magnet and the sixth permanent magnet.

[0007] The first magnet group and a corresponding group of the second magnet groups are symmetrically arranged about the d-axis of the rotor core.

[0008] According to the rotor assembly of some embodiments of the present invention, in the length direction of the first mounting slot, the second permanent magnet is located on a side of the first permanent magnet close to the d-axis.

[0009] According to the rotor assembly of some embodiments of the present invention, the width of the second permanent magnet is smaller than the width of the first permanent magnet and the third permanent magnet, and the length of the second permanent magnet is greater than the length of the first permanent magnet and the third permanent magnet.

[0010] According to some embodiments of the rotor assembly of the present invention, the first mounting slot includes a first sub-slot and a second sub-slot, the width of the first sub-slot is smaller than the width of the second sub-slot, the second permanent magnet is placed in the first sub-slot, and the first permanent magnet and the third permanent magnet are respectively placed in the second sub-slot.

[0011] According to the rotor assembly of some embodiments of the present invention, the first permanent magnet and the third permanent magnet are ferrite magnets, respectively, and the second permanent magnet is rare earth magnet.

[0012] According to the rotor assembly of some embodiments of the present invention, on the same cross section of the rotor core, the length of a first line between the geometric center of the first permanent magnet and the center of the rotor core is L1, the length of a second line between the geometric center of the second permanent magnet and the center of the rotor core is L2, and the length of a third line between the geometric center of the third permanent magnet and the center of the rotor core is L3, wherein the rotor assembly satisfies the following relationship:

[0013] According to the rotor assembly of some embodiments of the present invention, on the same cross section of the rotor core, the line between the geometric center of the first permanent magnet and the center of the rotor core is a first line, the line between the geometric center of the second permanent magnet and the center of the rotor core is a second line, the line between the geometric center of the third permanent magnet and the center of the rotor core is a third line, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, and the angle between the third line and the d-axis is α3, wherein the rotor assembly satisfies the following relationship:

[0014] According to the rotor assembly of some embodiments of the present invention, on the same cross section of the rotor core, the length of the first line between the geometric center of the first permanent magnet and the center of the rotor core is L1, the length of the second line between the geometric center of the second permanent magnet and the center of the rotor core is L2, the width of the first permanent magnet is W1, the width of the second permanent magnet is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, the angle between the third line and the d-axis is α3, and the rotor assembly satisfies the following relationship:

[0015] According to the rotor assembly of some embodiments of the present invention, on the same cross section of the rotor core, the length of the first line between the geometric center of the first permanent magnet and the center of the rotor core is L1, the length of the third line between the geometric center of the third permanent magnet and the center of the rotor core is L3, the width of the first permanent magnet is W1, the width of the second permanent magnet is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, the angle between the third line and the d-axis is α3, and the rotor assembly satisfies the following relationship:

[0016] According to the rotor assembly of some embodiments of the present invention, on the same cross section of the rotor core, the length of the second line between the geometric center of the second permanent magnet and the center of the rotor core is L2, the length of the third line between the geometric center of the third permanent magnet and the center of the rotor core is L3, the width of the first permanent magnet is W1, the width of the second permanent magnet is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, the angle between the third line and the d-axis is α3, and the rotor assembly satisfies the following relationship:

[0017] According to the rotor assembly of some embodiments of the present invention, the width of the first permanent magnet is W1, the width of the second permanent magnet is W2, the remanence of the first permanent magnet is Br1, the remanence of the second permanent magnet is Br2, and the remanence of the third permanent magnet is Br3, wherein Br1=Br3,

[0018] According to the rotor assembly of some embodiments of the present invention, the coercive force of the first permanent magnet is Hc1, the coercive force of the second permanent magnet is Hc2, the coercive force of the third permanent magnet is Hc3, the width of the second permanent magnet is W2, the width of the third permanent magnet is W3, wherein Hc1=Hc3, Where e is a natural constant.

[0019] The invention also provides a motor.

[0020] The motor according to the embodiment of the present invention comprises: a rotor assembly, wherein the rotor assembly is the rotor assembly according to any of the above embodiments; and a stator assembly, wherein the stator assembly cooperates with the rotor assembly.

[0021] According to the motor of the embodiment of the present invention, a first magnet group is provided in the first mounting groove of the rotor core, and the first magnet group is provided to include a first permanent magnet, a second permanent magnet and a third permanent magnet arranged in sequence, thereby reducing the cogging torque generated by the rotor assembly during rotation, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter caused by the torque fluctuation, and helping to improve the NVH performance. In addition, by setting the remanence of the second permanent magnet to be higher than the remanence of the first permanent magnet and the third permanent magnet, for example, setting the first permanent magnet and the third permanent magnet to be ferrite magnets, such a setting reduces the amount of rare earth magnets in the rotor assembly, reduces the cost of the rotor assembly, and allows the ferrite magnets to protect the rare earth magnets to reduce the risk of demagnetization of the rare earth magnets, thereby improving the practicality of the motor.

[0022] The present invention also provides a vehicle.

[0023] A vehicle according to an embodiment of the present invention comprises the motor according to any one of the above embodiments.

[0024] According to the vehicle of the embodiment of the present invention, a first magnet group is provided in the first mounting groove of the rotor core, and the first magnet group is provided to include a first permanent magnet, a second permanent magnet and a third permanent magnet arranged in sequence, thereby reducing the cogging torque generated by the rotor assembly during rotation, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter caused by the torque fluctuation, and helping to improve the NVH performance. In addition, by setting the remanence of the second permanent magnet to be higher than the remanence of the first permanent magnet and the third permanent magnet, for example, setting the first permanent magnet and the third permanent magnet to be ferrite magnets, such a setting reduces the amount of rare earth magnets in the rotor assembly, reduces the cost of the rotor assembly, and allows the ferrite magnets to protect the rare earth magnets to reduce the risk of demagnetization of the rare earth magnets, thereby improving the practicability of the motor and improving the overall performance of the vehicle.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 is a schematic diagram of a rotor assembly according to an embodiment of the present invention;

[0028] Figure 2 is a partial schematic diagram of a rotor assembly according to an embodiment of the present invention;

[0029] Figure 3 is a partial schematic diagram of a rotor assembly according to an embodiment of the present invention;

[0030] Figure 4 is a partial schematic diagram of a rotor assembly according to another embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of the cogging torque waveform when a mixed magnetic steel arrangement is used in the same slot in the prior art;

[0032] Figure 6 It is a schematic diagram of the torque fluctuation waveform when a mixed magnetic steel arrangement is used in the same slot in the prior art;

[0033] Figure 7 It is a schematic diagram of the cogging torque waveform when only NdFeB magnets are used in the same slot in the prior art;

[0034] Figure 8 It is a schematic diagram of the torque fluctuation waveform when only NdFeB magnets are used in the same slot in the prior art.

[0035] Reference numerals:

[0036] Rotor assembly 100,

[0037] Rotor core 1, first mounting groove 11, first sub-groove 111, second sub-groove 112, second mounting groove 12, third mounting groove 13,

[0038] The first magnet group 2, the first permanent magnet 21, the second permanent magnet 22, the third permanent magnet 23,

[0039] The second magnet group 3 , the fourth permanent magnet 31 , the fifth permanent magnet 32 ​​, the sixth permanent magnet 33 , and the seventh permanent magnet 4 . DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Hereinafter, a rotor assembly 100 according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0044] like Figure 1-Figure 8As shown, a rotor assembly 100 according to an embodiment of the present invention includes: a rotor core 1, the rotor core 1 is provided with a plurality of first mounting grooves 11, the plurality of first mounting grooves 11 are arranged at intervals along the circumferential direction of the rotor core 1, and a first magnet group 2 is arranged in each first mounting groove 11; the first magnet group 2 includes a first permanent magnet 21, a second permanent magnet 22 and a third permanent magnet 23, the first permanent magnet 21 and the third permanent magnet 23 are located on both sides of the second permanent magnet 22, the remanence of the second permanent magnet 22 is higher than the remanence of the first permanent magnet 21, the remanence of the second permanent magnet 22 is higher than the remanence of the third permanent magnet 23, and the material of the second permanent magnet 22 is different from the materials of the first permanent magnet 21 and the third permanent magnet 23.

[0045] Therefore, by providing a first magnet group 2 in the first mounting groove 11 of the rotor core 1, and setting the first magnet group 2 to include a first permanent magnet 21, a second permanent magnet 22 and a third permanent magnet 23 arranged in sequence, the cogging torque generated by the rotor assembly 100 during rotation is reduced, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter caused by the torque fluctuation, and helping to improve the NVH performance. By setting the remanence of the second permanent magnet 22 to be higher than the remanence of the first permanent magnet 21 and the third permanent magnet 23, for example, setting the first permanent magnet 21 and the third permanent magnet 23 to be ferrite magnets, such a setting reduces the amount of rare earth magnets in the rotor assembly 100, reduces the cost of the rotor assembly 100, and allows the ferrite magnets to protect the rare earth magnets to reduce the risk of demagnetization of the rare earth magnets.

[0046] like Figure 5-Figure 8 As shown, Figure 5 This is the cogging torque waveform when the original scheme uses a mixed magnetic steel arrangement in the same slot, and the value is 340.7256Mnm. Figure 7 This is the cogging torque waveform when the original scheme uses only NdFeB magnets in the same slot, and the value is 893.8081Mnm. Figure 6 This is the torque fluctuation waveform diagram when the original scheme adopts the mixed magnetic steel arrangement in the same slot. The torque fluctuation is 0.1722%. Figure 8 This is the torque fluctuation waveform diagram when the original solution uses only NdFeB magnets in the same slot, with a torque fluctuation of 0.1991%.

[0047] According to the simulation results, under the same conditions, when the mixed magnets are arranged in the same slot, the cogging torque is reduced by 553.0825Mnm, that is, the cogging torque is reduced by 61.9%, and the torque fluctuation is reduced by 0.0269%.

[0048] For example, refer to Figure 1-Figure 3As shown, the rotor assembly 100 includes a rotor core 1, which is configured as an annular structure, and is formed by stacking a plurality of steel sheets in sequence along the axial direction. The rotor core 1 is provided with a plurality of mounting slot groups, and the plurality of mounting slot groups are evenly spaced along the circumference of the rotor core 1, and each mounting slot group includes a first mounting slot 11, so that the plurality of first mounting slots 11 can be sequentially arranged along the circumference of the rotor core 1, and a first magnet group 2 is installed in the first mounting slot 11.

[0049] Among them, the first magnet group 2 can be set to include a first permanent magnet 21, a second permanent magnet 22 and a third permanent magnet 23 arranged in segments. The first permanent magnet 21, the second permanent magnet 22 and the third permanent magnet 23 can be evenly segmented or non-uniformly segmented. The first permanent magnet 21, the second permanent magnet 22 and the third permanent magnet 23 are arranged in sequence along the length direction of the first mounting groove 11. The two ends of the second permanent magnet 22 along the length direction can be respectively opposite to the ends of the first permanent magnet 21 and the third permanent magnet 23 along the length direction, and can be connected by gluing or welding.

[0050] It should be noted that, according to the principle of superposition method, the total cogging torque of each pole of the motor can be simplified to the superposition of the cogging torque generated by each permanent magnet, satisfying:

[0051]

[0052] Where: Ns is the number of segments of the permanent magnet; Tn is the amplitude of the cogging torque of the nth harmonic; Np is the number of cogging torque cycles of one pitch; Z is the number of slots; Δβ is the offset angle between two adjacent segments of the permanent magnet. The number of cogging torque cycles of one pitch: Np = 2p / GCD (Z, 2p), where: GCD (Z, 2p) represents the greatest common divisor of Z and 2p. It can be seen from the above formula that by changing the number of segments Ns of the permanent magnet, the total cogging torque of each pole can be effectively weakened.

[0053] Therefore, the first magnet group 2 can be installed in the first installation groove 11, and the first magnet group 2 can be arranged to have a first permanent magnet 21, a second permanent magnet 22 and a third permanent magnet 23 that are arranged in segments to reduce the cogging torque, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter problem caused by the unstable output caused by the torque fluctuation, and helping to improve the NVH performance.

[0054] Among them, the remanence of the second permanent magnet 22 can be set higher than the remanence of the first permanent magnet 21, and the remanence of the second permanent magnet 22 can be set higher than the remanence of the third permanent magnet 23, and the first permanent magnet 21 and the third permanent magnet 23 can be set to be different from the material of the second permanent magnet 22, such as the second permanent magnet 22 can be set to a rare earth permanent magnet, and the first permanent magnet 21 and the third permanent magnet 23 can be set to a ferrite permanent magnet; or, the second permanent magnet 22 can be set to a ferrite permanent magnet, and the first permanent magnet 21 and the third permanent magnet 23 can be set to a ferrite permanent magnet; or permanent magnets of the same type but with different remanences can be satisfied, and the remanence of the second permanent magnet 22 is high, and the remanence of the first permanent magnet 21 and the third permanent magnet 23 is low, and this application does not limit this. In this way, the risk of demagnetization of rare earth magnets can be reduced, and the amount of rare earth magnets can be reduced, reducing costs. Thus, the reliability of the rotor assembly 100 is improved.

[0055] It should be noted that the same permanent magnet material means that the components contained in the permanent magnet are exactly the same. Otherwise, they are all permanent magnets of different materials, such as the following situations:

[0056] 1. Permanent magnets are of different types. For example, ferrite magnets and NdFeB magnets are permanent magnets of different types and materials. Rare earth materials such as samarium cobalt magnets and NdFeB magnets also belong to this situation, that is, permanent magnets of different types and materials.

[0057] 2. Permanent magnets of the same model but different grades also belong to permanent magnets of different materials. For example, they are all aluminum-cobalt-nickel magnets, but the same volume of aluminum-cobalt-nickel magnets will have different performances due to the different proportions of aluminum, cobalt, and nickel. Therefore, grades are added to aluminum-cobalt-nickel to identify the performance of the magnets for different output remanence and other properties. For example, LNG13 and LNG32, where L stands for aluminum, N stands for nickel, and G stands for cobalt. The remanence of LNG13 is 0.68, while the remanence of LNG32 is 1.2. Therefore, the remanence performance of LNG32 is better than that of LNG13, but the cost of LNG32 is higher than that of LNG13.

[0058] The above description is only an example of different materials. As long as the two permanent magnets contain different components, they can be considered as permanent magnets of different materials in the present application.

[0059] In some embodiments of the present invention, the rotor core is further provided with a plurality of second mounting grooves 12, and the plurality of first mounting grooves 11 and the plurality of second mounting grooves 12 are alternately arranged along the circumferential direction of the rotor core 1, and a second magnet group 3 is arranged in each second mounting groove 12, and the second magnet group 3 includes a fourth permanent magnet 31, a fifth permanent magnet 32 ​​and a sixth permanent magnet 33, and the fourth permanent magnet 31 and the sixth permanent magnet 33 are located on both sides of the fifth permanent magnet 32, and the residual magnetism of the fifth permanent magnet 32 ​​is higher than the residual magnetism of the fourth permanent magnet 31, and the residual magnetism of the fifth permanent magnet 32 ​​is higher than the residual magnetism of the sixth permanent magnet 33, and the material of the fifth permanent magnet 32 ​​is different from the material of the fourth permanent magnet 31 and the sixth permanent magnet 33, and the first magnet group 2 and a corresponding group of second magnet groups 3 are symmetrically arranged about the d axis of the rotor core 1.

[0060] For example, refer to Figure 1-Figure 3 As shown, each mounting groove group further includes a second mounting groove 12, and the first mounting groove 11 and the second mounting groove 12 are arranged at intervals along the circumferential direction of the rotor core 1, so that a plurality of first mounting grooves 11 and a plurality of second mounting grooves 12 can be arranged alternately and sequentially along the circumferential direction of the rotor core 1, and a second magnet group 3 is installed in the second permanent magnet 22. The second magnet group 3 can be arranged to include a fourth permanent magnet 31, a fifth permanent magnet 32 ​​and a sixth permanent magnet 33 arranged in sections, and the fourth permanent magnet 31, the fifth permanent magnet 32 ​​and the sixth permanent magnet 33 can be evenly segmented or non-evenly segmented, and the fourth permanent magnet 31, the fifth permanent magnet 32 ​​and the sixth permanent magnet 33 are arranged in sequence along the length direction of the second mounting groove 12, and the two ends of the fifth permanent magnet 32 ​​along the length direction can be respectively opposite to the ends of the fifth permanent magnet 32 ​​and the sixth permanent magnet 33 along the length direction, and can be connected by gluing or welding.

[0061] Among them, the remanence of the fifth permanent magnet 32 ​​can be set higher than the remanence of the fourth permanent magnet 31, and the remanence of the fifth permanent magnet 32 ​​can be set higher than the remanence of the sixth permanent magnet 33, and the fourth permanent magnet 31 and the sixth permanent magnet 33 can be set to be different from the material of the fifth permanent magnet 32, such as the fifth permanent magnet 32 ​​can be set to a rare earth permanent magnet, and the fourth permanent magnet 31 and the sixth permanent magnet 33 can be set to a ferrite permanent magnet; or, the fifth permanent magnet 32 ​​can be set to a ferrite permanent magnet, and the fourth permanent magnet 31 and the sixth permanent magnet 33 can be set to a ferrite permanent magnet; or permanent magnets of the same type but with different remanences can be satisfied, and the remanence of the fifth permanent magnet 32 ​​is high, and the remanence of the fourth permanent magnet 31 and the sixth permanent magnet 33 is low, and this application does not limit this. In this way, the risk of demagnetization of rare earth magnets can be reduced, and the amount of rare earth magnets can be reduced, reducing costs. Thus, the reliability of the rotor assembly 100 is improved.

[0062] At the same time, the first mounting slot 11 and the second mounting slot 12 in the same mounting slot group can be arranged symmetrically about the d-axis of the rotor core 1, so that the first magnet group 2 installed in the first mounting slot 11 and the second magnet group 3 installed in the second mounting slot 12 are symmetrical, that is, the first permanent magnet 21 and the fourth permanent magnet 31 are arranged symmetrically about the d-axis, and the second permanent magnet 22 and the fifth permanent magnet 32 ​​are arranged symmetrically about the d-axis, and the third permanent magnet 23 and the sixth permanent magnet 33 are arranged symmetrically about the d-axis. In this way, the first magnet group 2 and the second magnet group 3 on the rotor assembly 100 are evenly distributed. As a result, it is beneficial to reduce the cogging torque generated by the rotor assembly 100 during rotation, reduce the torque fluctuation caused by the cogging torque, reduce the jitter problem caused by the unstable output caused by the torque fluctuation, and help improve the NVH performance.

[0063] In some embodiments of the present invention, in the length direction of the first installation slot 11 , the second permanent magnet 22 is located on a side of the first permanent magnet 21 close to the d-axis.

[0064] For example, refer to Figure 2-Figure 3 As shown, the first permanent magnet 21 can be arranged at one end of the first mounting groove 11 away from the d-axis, the second permanent magnet 22 can be arranged at one side of the first permanent magnet 21 close to the d-axis, and the third permanent magnet 23 can be arranged at one side of the second permanent magnet 22 close to the d-axis, so that the first permanent magnet 21, the second permanent magnet 22 and the third permanent magnet 23 can be arranged in sequence along the length direction of the first mounting groove 11. Correspondingly, the fourth permanent magnet 31 can be arranged at one end of the second mounting groove 12 away from the d-axis, the fifth permanent magnet 32 ​​can be arranged at one side of the fourth permanent magnet 31 close to the d-axis, and the sixth permanent magnet 33 can be arranged at one side of the fifth permanent magnet 32 ​​close to the d-axis, so that the fourth permanent magnet 31, the fifth permanent magnet 32 ​​and the sixth permanent magnet 33 can be arranged in sequence along the length direction of the second mounting groove 12. Thus, the orderly arrangement of the first magnet group 2 and the second magnet group 3 is achieved.

[0065] In some embodiments of the present invention, the width of the second permanent magnet 22 is smaller than the width of the first permanent magnet 21 and the third permanent magnet 23, and the length of the second permanent magnet 22 is greater than the length of the first permanent magnet 21 and the third permanent magnet 23. Figure 2-Figure 3As shown, the width of the second permanent magnet 22 can be set to be smaller than the width of the first permanent magnet 21, and the length of the second permanent magnet 22 can be set to be greater than the length of the first permanent magnet 21. At the same time, the width of the second permanent magnet 22 can be set to be smaller than the width of the third permanent magnet 23, and the length of the second permanent magnet 22 can be set to be greater than the length of the third permanent magnet 23. Specifically, the width of the second permanent magnet 22 can be set to be between 2.5 mm and 7 mm, and the widths of the first permanent magnet 21 and the third permanent magnet 23 can be set to be between 5 mm and 12 mm, and the width ratio of the second permanent magnet 22 to the first permanent magnet 21 and the third permanent magnet 23 can be maintained between 0.3-1.2.

[0066] After adopting the above-mentioned size limit range, the distribution of magnetic lines of force can be changed so that the first permanent magnet 21 and the second permanent magnet 22 distributed at both ends have a larger thickness and are not easily demagnetized, thereby reducing the demagnetization effect on the first magnet group 2, or even not being affected by demagnetization, and avoiding the first permanent magnet 21, the second permanent magnet 22 and the third permanent magnet 23 from being too large in size, which is beneficial to reducing costs.

[0067] In some embodiments of the present invention, the first mounting groove 11 includes a first sub-groove 111 and a second sub-groove 112, the width of the first sub-groove 111 is smaller than the width of the second sub-groove 112, the second permanent magnet 22 is placed in the first sub-groove 111, and the first permanent magnet and the third permanent magnet 23 are placed in the second sub-groove 112 respectively.

[0068] For example, refer to Figure 3 As shown, the first installation slot 11 includes a first sub-slot 111 and a second sub-slot 112, and the second sub-slot 112 is provided with two, and the two second sub-slots 112 are respectively provided on both sides of the first sub-slot 111 along the length direction, and the width of the first sub-slot 111 corresponds to the second permanent magnet 22. The width of the second sub-slot 112 can be set to be greater than the width of the first sub-slot 111, and the width of the first permanent magnet 21 and the width of the third permanent magnet 23 are set to be equal, so that the first permanent magnet 21 and the third permanent magnet 23 can correspond to the two second sub-slots 112 respectively. In this way, the second permanent magnet 22 can be placed in the first sub-slot 111 accordingly, and the first permanent magnet 21 and the third permanent magnet 23 can be placed in the two second sub-slots 112 respectively, so as to realize the installation of the first magnet group 2.

[0069] The above arrangement helps to reduce the difficulty of installing the first magnet group 2, and there is no need to consider the demagnetization problem caused by the segmentation of the permanent magnet. It avoids the damage to the permanent magnet caused by the use of shrink-fit or tooling to forcibly install it into the corresponding slot when the permanent magnet cannot be installed. It indirectly avoids the destruction of the magnetic properties of the permanent magnet itself and the risk of reduced output torque or even demagnetization caused by the destruction of the permanent magnet, thereby improving the reliability of the rotor assembly 100.

[0070] In some embodiments of the present invention, the first permanent magnet 21 and the third permanent magnet 23 are ferrite magnets, respectively, and the second permanent magnet 22 is a rare earth magnet. It is understandable that by placing ferrite magnets with a larger width at both ends of the first mounting slot 11, and placing rare earth magnets (such as NdFeB magnets and Cedar magnets) in the middle of the first mounting slot 11, the ferrite magnets have sufficient thickness and are not easily demagnetized. The ferrite magnets can protect the rare earth magnets, thereby preventing the rare earth magnets from being demagnetized, improving the reliability of the rotor assembly 100, and helping to reduce the amount of rare earth magnets and reduce costs.

[0071] Of course, the present invention is not limited to this. The first permanent magnet 21 and the second permanent magnet 22 can also be set as neodymium iron boron magnets, and the third permanent magnet 23 can be set as ferrite magnets; or, the first permanent magnet 21 and the third permanent magnet 23 can be set as magnets with a smaller grade and a smaller residual magnetism among the same type of magnets, and the second permanent magnet 22 can be set as a magnet with a larger grade and a larger residual magnetism among the same type of magnets. The present application does not impose any restrictions on this.

[0072] It should be noted that, refer to Figure 4 As shown, a third mounting groove 13 can also be provided on the radial outer side of the first mounting groove 11 and the second mounting groove 12, respectively. The two third mounting grooves 13 are symmetrically arranged about the d axis, and the seventh permanent magnet 4 is provided in the third mounting groove 13. Among them, the first permanent magnet 21 and the third permanent magnet 23 can be ferrite magnets, respectively, and the second permanent magnet 22 and the seventh permanent magnet 4 can be set as neodymium iron boron magnets; or, the first permanent magnet 21 and the third permanent magnet 23 can be ferrite magnets, respectively, and the second permanent magnet 22 can be set as neodymium iron boron magnets, and the seventh permanent magnet 4 can be set as cedar cobalt magnets; or, the first permanent magnet 21 and the third permanent magnet 23 can be ferrite magnets, respectively, and the second permanent magnet 22 can be set as cedar cobalt magnets, and the seventh permanent magnet 4 can be set as neodymium iron boron magnets, and the present application does not limit this. Thus, it is conducive to meeting different working conditions.

[0073] In some embodiments of the present invention, on the same cross section of the rotor core 1, the length of the first line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 is L1, the length of the second line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 is L2, and the length of the third line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 is L3, wherein the rotor assembly 100 satisfies the following relationship:

[0074] For example, refer to Figure 3As shown, in the direction away from the d-axis, the first installation groove 11 is arranged to extend obliquely toward the radial outer side of the rotor core 1, and the third permanent magnet 23, the second permanent magnet 22 and the first permanent magnet 21 are sequentially arranged in the first installation groove 11. The line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 can be set as the first line, and the length of the first line is set as L1; the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 can be set as the second line, and the length of the second line is set as L2; ​​the line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 can be set as the third line, and the length of the third line is set as L3.

[0075] The rotor assembly 100 satisfies the following relationship: That is to say, the ratio of the length of the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 to the length of the line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 is greater than or equal to 0.5 times the ratio of the length of the line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 to the length of the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1, and is less than or equal to 2.03 times the ratio of the length of the line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 to the length of the line between the geometric center of the fourth permanent magnet 31 and the center of the rotor core 1. When L1, L2, and L3 are changed, that is, the first permanent magnet 21, the second permanent magnet 22, and the third permanent magnet 23 change with the center of the rotor core 1, the pole arc coefficient will change, and the pole arc coefficient is determined by the ratio of the average magnetic flux density of the air gap to the maximum magnetic flux density of the air gap. There is an optimal range for the pole arc coefficient, within which the air gap magnetic flux waveform is closest to a sine wave. Therefore, the relationship between the distances L1, L2, and L3 is limited within the above range, so that the air gap magnetic flux waveform is closest to a sine wave, the cogging torque has a smaller range, and the torque fluctuation also has a smaller range. This reduces torque fluctuation and cogging torque, and improves NVH performance.

[0076] In a more preferred embodiment, the rotor assembly 100 satisfies the following relationship: Its effect is more obvious than the above content.

[0077] In some embodiments of the present invention, on the same cross section of the rotor core 1, the line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 is the first line, the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 is the second line, the line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 is the third line, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, and the angle between the third line and the d-axis is α3, wherein the rotor assembly 100 satisfies the following relationship:

[0078] For example, refer to Figure 3 As shown, in the direction away from the d-axis, the first installation groove 11 is set to extend obliquely toward the radial outer side of the rotor core 1, and the third permanent magnet 23, the second permanent magnet 22 and the first permanent magnet 21 are sequentially arranged in the first installation groove 11. The line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 can be set as the first line, the first line is located on one side of the d-axis, and the angle between the first line and the d-axis is set as α1; the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 can be set as the second line, the second line is located on one side of the d-axis, and the angle between the second line and the d-axis is set as α2; the line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 can be set as the third line, the third line is located on one side of the d-axis, and the angle between the third line and the d-axis is set as α3.

[0079] The rotor assembly 100 satisfies the following relationship: That is, the ratio of the sine function of the angle between the triple second connecting line and the d-axis to the sine function of the angle between the triple third connecting line and the d-axis can be set to be greater than or equal to 1.3 times. and less than or equal to 0.81 times When α1, α2, and α3 are changed, it is equivalent to changing the pole arc coefficient of the rotor 100. The pole arc coefficient has an optimal range. Within this range, the air gap flux density waveform is closest to a sine wave, the torque fluctuation is small, and the cogging torque has a smaller range. Therefore, the relationship between the above α1, α2, and α3 is limited to the above range, so that the air gap flux density waveform is closest to a sine wave, the cogging torque has a smaller range, and the torque fluctuation also has a smaller range. In this way, the torque fluctuation and cogging torque are reduced, and the NVH performance is improved.

[0080] In a more preferred embodiment, the rotor assembly 100 satisfies the following relationship: Its effect is more obvious than the above content.

[0081] In some embodiments of the present invention, on the same cross section of the rotor core 1, the length of the first line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 is L1, the length of the second line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 is L2, the width of the first permanent magnet 21 is W1, the width of the second permanent magnet 22 is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, and the angle between the third line and the d-axis is α3, and the rotor assembly 100 satisfies the following relationship:

[0082] For example, refer to Figure 3 As shown, in the direction away from the d-axis, the first installation groove 11 is set to extend obliquely toward the radial outer side of the rotor core 1, and the third permanent magnet 23, the second permanent magnet 22 and the first permanent magnet 21 are sequentially arranged in the first installation groove 11. The line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 can be set as the first line, the length of the first line is set as L1, the first line is located on one side of the d-axis, and the angle between the first line and the d-axis is set as α1; the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 can be set as the second line, the length of the second line is set as L2, the second line is located on one side of the d-axis, and the angle between the second line and the d-axis is set as α2; the line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 can be set as the third line, the length of the third line is set as L3, the third line is located on one side of the d-axis, and the angle between the third line and the d-axis is set as α3. Meanwhile, the width of the first permanent magnet 21 may be set to W1, and the width of the second permanent magnet 22 may be set to W2.

[0083] The rotor assembly 100 satisfies the following relationship: That is, the ratio between the width of the first permanent magnet 21 and the width of the second permanent magnet 22 is greater than or equal to 0.01 times the length L1 of the first connecting line multiplied by and less than or equal to 0.02 times the length of the second line L2 multiplied by By changing the angle between the line connecting the geometric center of the permanent magnet and the center of the rotor core 1 and the d-axis, it is equivalent to changing the pole arc coefficient of the rotor assembly 100, and the pole arc coefficient has an optimal range, within which the air gap magnetic flux waveform is closest to a sine wave, the torque fluctuation is small, and the tooth slot torque has a smaller range. Therefore, by changing the angle between the permanent magnet and the d-axis, and combining the width of the permanent magnet and the distance from the geometric center of the permanent magnet to the center of the rotor core 1, the rationality of the layout of the first magnet group 2 is improved, which is conducive to reducing the torque fluctuation of the rotor assembly 100, improving the NVH performance, and also improving the anti-demagnetization performance of the permanent magnet.

[0084] In a more preferred embodiment, the rotor assembly 100 satisfies the following relationship: Its effect is more obvious than the above content.

[0085] In some embodiments of the present invention, on the same cross section of the rotor core 1, the length of the first line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 is L1, the length of the third line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 is L3, the width of the first permanent magnet 21 is W1, the width of the second permanent magnet 22 is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, and the angle between the third line and the d-axis is α3, and the rotor assembly 100 satisfies the following relationship:

[0086] For example, refer to Figure 3 As shown, in the direction away from the d-axis, the first installation groove 11 is set to extend obliquely toward the radial outer side of the rotor core 1, and the third permanent magnet 23, the second permanent magnet 22 and the first permanent magnet 21 are sequentially arranged in the first installation groove 11. The line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 can be set as the first line, the length of the first line is set as L1, the first line is located on one side of the d-axis, and the angle between the first line and the d-axis is set as α1; the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 can be set as the second line, the length of the second line is set as L2, the second line is located on one side of the d-axis, and the angle between the second line and the d-axis is set as α2; the line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 can be set as the third line, the length of the third line is set as L3, the third line is located on one side of the d-axis, and the angle between the third line and the d-axis is set as α3. Meanwhile, the width of the first permanent magnet 21 may be set to W1, and the width of the second permanent magnet 22 may be set to W2.

[0087] The rotor assembly 100 satisfies the following relationship: That is, the ratio between the width of the first permanent magnet 21 and the width of the second permanent magnet 22 is greater than or equal to 0.01 times the length L3 of the third connecting line multiplied by and is less than or equal to 0.1 times the length of the first connecting line L1 multiplied by By changing the angle between the geometric center of the permanent magnet and the center line of the rotor core 1 and the d-axis, it is equivalent to changing the pole arc coefficient of the rotor assembly 100, and the pole arc coefficient has an optimal range, within which the air gap magnetic flux waveform is closest to a sine wave, the torque fluctuation is small, and the tooth slot torque has a smaller range. Therefore, by changing the angle between the permanent magnet and the d-axis, and combining the width of the permanent magnet and the distance from the geometric center of the permanent magnet to the center of the rotor core 1, the rationality of the layout of the first magnet group 2 is improved, which is conducive to reducing the torque fluctuation of the rotor assembly 100, improving the NVH performance, and also improving the anti-demagnetization performance of the permanent magnet.

[0088] In a more preferred embodiment, the rotor assembly 100 satisfies the following relationship: Its effect is more obvious than the above content.

[0089] In some embodiments of the present invention, on the same cross section of the rotor core 1, the length of the second line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 is L2, the length of the third line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 is L3, the width of the first permanent magnet 21 is W1, the width of the second permanent magnet 22 is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, and the angle between the third line and the d-axis is α3, and the rotor assembly 100 satisfies the following relationship:

[0090] For example, refer to Figure 3 As shown, in the direction away from the d-axis, the first installation groove 11 is set to extend obliquely toward the radial outer side of the rotor core 1, and the third permanent magnet 23, the second permanent magnet 22 and the first permanent magnet 21 are sequentially arranged in the first installation groove 11. The line between the geometric center of the first permanent magnet 21 and the center of the rotor core 1 can be set as the first line, the length of the first line is set as L1, the first line is located on one side of the d-axis, and the angle between the first line and the d-axis is set as α1; the line between the geometric center of the second permanent magnet 22 and the center of the rotor core 1 can be set as the second line, the length of the second line is set as L2, the second line is located on one side of the d-axis, and the angle between the second line and the d-axis is set as α2; the line between the geometric center of the third permanent magnet 23 and the center of the rotor core 1 can be set as the third line, the length of the third line is set as L3, the third line is located on one side of the d-axis, and the angle between the third line and the d-axis is set as α3. Meanwhile, the width of the first permanent magnet 21 may be set to W1, and the width of the second permanent magnet 22 may be set to W2.

[0091] The rotor assembly 100 satisfies the following relationship: That is, the ratio between the width of the first permanent magnet 21 and the width of the second permanent magnet 22 is greater than or equal to 0.01 times the length L2 of the second connecting line multiplied by and less than or equal to 0.03 times the length of the third line L3 multiplied by By changing the angle between the geometric center of the permanent magnet and the center line of the rotor core 1 and the d-axis, it is equivalent to changing the pole arc coefficient of the rotor assembly 100, and the pole arc coefficient has an optimal range, within which the air gap magnetic flux waveform is closest to a sine wave, the torque fluctuation is small, and the tooth slot torque has a smaller range. Therefore, by changing the angle between the permanent magnet and the d-axis, and combining the width of the permanent magnet and the distance from the geometric center of the permanent magnet to the center of the rotor core 1, the rationality of the layout of the first magnet group 2 is improved, which is conducive to reducing the torque fluctuation of the rotor assembly 100, improving the NVH performance, and also improving the anti-demagnetization performance of the permanent magnet.

[0092] In a more preferred embodiment, the rotor assembly 100 satisfies the following relationship: Its effect is more obvious than the above content.

[0093] In some embodiments of the present invention, the width of the first permanent magnet 21 is W1, the width of the second permanent magnet 22 is W2, the remanence of the first permanent magnet 21 is Br1, the remanence of the second permanent magnet 22 is Br2, and the remanence of the third permanent magnet 23 is Br3, wherein Br1=Br3,

[0094] For example, refer to Figure 3 As shown, the width of the first permanent magnet 21 can be set to W1, and the remanence of the first permanent magnet 21 can be set to Br1; the width of the second permanent magnet 22 can be set to W2, and the remanence of the second permanent magnet 22 can be set to Br2; the remanence of the third permanent magnet 23 can be set to Br3, and the remanence Br1 of the first permanent magnet 21 is set equal to the remanence Br3 of the third permanent magnet 23.

[0095] The rotor assembly 100 satisfies the following relationship: That is to say, the ratio between the width of the first permanent magnet 21 and the width of the second permanent magnet 22 is greater than or equal to 1.25 times the ratio between the remanence of the first permanent magnet 21 and the remanence of the third permanent magnet 23, and less than or equal to 1.5 times the remanence of the second permanent magnet 22. When the remanence of the permanent magnet is changed, that is, when Br1, Br2, and Br3 are changed, the anti-demagnetization ability of the permanent magnet will be affected. The larger the remanence, the stronger the anti-demagnetization ability of the permanent magnet, and the greater the load torque that the permanent magnet can provide; conversely, the smaller the remanence, the weaker the anti-demagnetization ability of the permanent magnet, and the smaller the load torque that the permanent magnet can provide. There is an optimal range for the pole arc coefficient. When the above parameter relationship is met, the remanence is within the optimal range, that is, the anti-demagnetization ability and the load torque are within the most suitable range.

[0096] In a more preferred embodiment, the rotor assembly 100 satisfies the following relationship: Its effect is more obvious than the above content.

[0097] In some embodiments of the present invention, the coercive force of the first permanent magnet 21 is Hc1, the coercive force of the second permanent magnet 22 is Hc2, the coercive force of the third permanent magnet 23 is Hc3, the width of the second permanent magnet 22 is W2, and the width of the third permanent magnet 23 is W3, wherein Hc1=Hc3,

[0098] For example, refer to Figure 3 As shown, the width of the second permanent magnet 22 can be set to W2, and the coercive force of the second permanent magnet 22 can be set to Hc2; the width of the third permanent magnet 23 can be set to W3, and the coercive force of the third permanent magnet 23 can be set to Hc3; the coercive force of the first permanent magnet 21 can be set to Hc1, and the coercive force Hc1 of the first permanent magnet 21 is set equal to the coercive force Hc3 of the third permanent magnet 23.

[0099] The rotor assembly 100 satisfies the following relationship: Wherein e is a natural constant. That is to say, the ratio between the width of the second permanent magnet 22 and the width of the fourth permanent magnet 31 is greater than or equal to 8.5e-7 times the coercive force of the first permanent magnet 21, and less than or equal to 3e-6 times the coercive force of the second permanent magnet 22. When the coercive force of the permanent magnet is changed, that is, when Hc1, Hc2, and Hc3 are changed, the anti-demagnetization ability of the permanent magnet will be affected. The greater the coercive force, the higher the magnetomotive force; conversely, the smaller the coercive force, the smaller the magnetomotive force. There is an optimal range for the pole arc coefficient. When the above parameter relationship is met, the coercive force is within the optimal range, that is, the magnetomotive force is within the most suitable range.

[0100] In a more preferred embodiment, the rotor assembly 100 satisfies the following relationship: Its effect is more obvious than the above content.

[0101] It should be noted that when the rotor core 1 is provided with a first mounting groove 11 and a second mounting groove 12, a first magnet group 2 is provided in the first mounting groove 11, the first magnet group 2 includes a first permanent magnet 21, a second permanent magnet 22 and a third permanent magnet 23, a second magnet group 3 is installed in the second mounting groove 12, the second magnet group 3 includes a fourth permanent magnet 31, a fifth permanent magnet 32 ​​and a sixth magnet, and the first magnet group 2 and the second magnet group 3 are symmetrical about the d axis, if the following conditions are met at the same time:

[0102] (1)

[0103] (2)

[0104] (3)

[0105] (4)

[0106] (5)

[0107] (6)

[0108] (7)

[0109] Taking into account anti-demagnetization, reduction of torque fluctuation and improvement of NVH performance, the motor has the best overall performance.

[0110] Specifically, refer to Figure 5-Figure 8 As shown in the figure, when α1, α2, and α3 are changed, the air gap magnetic field of the motor is changed, and the load torque and NVH performance will be affected. When the above angle changes from small to large, the arc length spanned by the permanent magnet changes, thereby affecting the air gap magnetic density of the motor. The air gap magnetic density will fluctuate, the output power of the motor will fluctuate, and the NVH performance of the motor will fluctuate. There is an optimal coefficient range for the above angle, as shown in the above parameter expression. When within the above parameter range, the load torque and NVH performance of the motor are the best.

[0111] When W1, W2, and W3 are increased, the cost of the permanent magnet increases, affecting the working point of the permanent magnet, but the motor's anti-demagnetization ability is enhanced. When W1, W2, and W3 are reduced, the permanent magnet's anti-demagnetization ability is reduced, affecting the motor's output torque.

[0112] When the remanence and coercive force of the permanent magnet are changed, that is, when the Br1, Br2, Br3 and Hc1, Hc2, Hc3 of the permanent magnet are changed, the anti-demagnetization ability of the permanent magnet will be affected. The larger the Hc, the higher the magnetomotive force; the larger the Br, the stronger the anti-demagnetization ability of the permanent magnet, and the greater the load torque that the permanent magnet can provide; conversely, the smaller the Hc, the smaller the magnetomotive force; the smaller the Br, the weaker the anti-demagnetization ability of the permanent magnet, and the smaller the load torque that the permanent magnet can provide.

[0113] When L1, L2, and L3 are changed, α1, α2, and α3 will change. At this time, the motor's maximum speed, punching strength, and anti-leakage magnetic ability will have a fluctuation range. When the above parameter relationship is met, the motor's punching strength, maximum speed, and anti-leakage magnetic ability can theoretically reach the maximum value allowed by the punching. When W1, W2, and W3 change, the permanent magnet cost, anti-demagnetization ability, load torque, and NVH performance will fluctuate; α1, α2, and α3 change with the width of the permanent magnet, affecting the motor's pole arc coefficient, thereby affecting the motor's load torque and NVH performance. The pole arc coefficient has an optimal range. When the above parameter relationship is met, the pole arc coefficient is within the optimal range, and the motor's load torque and NVH performance are the best.

[0114] In summary, the restriction range in the above parameter relationship should be met. At this time, the motor performance is the best considering all factors.

[0115] The invention also provides a motor.

[0116] The motor according to the embodiment of the present invention comprises: a rotor assembly 100 and a stator assembly, wherein the rotor assembly 100 is the rotor assembly 100 of any of the above embodiments; and the stator assembly cooperates with the rotor assembly 100.

[0117] According to the motor of the embodiment of the present invention, by providing a first magnet group 2 in the first mounting groove 11 of the rotor core 1, and setting the first magnet group 2 to include a first permanent magnet 21, a second permanent magnet 22 and a third permanent magnet 23 arranged in sequence, the cogging torque generated by the rotor assembly 100 during rotation is reduced, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter caused by the torque fluctuation, and helping to improve the NVH performance. By setting the remanence of the second permanent magnet 22 to be higher than the remanence of the first permanent magnet 21 and the third permanent magnet 23, for example, setting the first permanent magnet 21 and the third permanent magnet 23 to be ferrite magnets, such a setting reduces the amount of rare earth magnets in the rotor assembly 100, reduces the cost of the rotor assembly 100, and allows the ferrite magnets to protect the rare earth magnets to reduce the risk of demagnetization of the rare earth magnets, thereby improving the practicality of the motor.

[0118] The present invention further provides a vehicle.

[0119] The vehicle according to the embodiment of the present invention includes the motor of any of the above embodiments. By providing the first magnet group 2 in the first mounting groove 11 of the rotor core 1, and setting the first magnet group 2 to include the first permanent magnet 21, the second permanent magnet 22 and the third permanent magnet 23 arranged in sequence, the cogging torque generated by the rotor assembly 100 during rotation is reduced, thereby reducing the torque fluctuation caused by the cogging torque, reducing the jitter caused by the torque fluctuation, and improving the NVH performance. By setting the remanence of the second permanent magnet 22 to be higher than the remanence of the first permanent magnet 21 and the third permanent magnet 23, for example, setting the first permanent magnet 21 and the third permanent magnet 23 to be ferrite magnets, such a setting reduces the amount of rare earth magnets in the rotor assembly 100, reduces the cost of the rotor assembly 100, and allows the ferrite magnets to protect the rare earth magnets to reduce the risk of demagnetization of the rare earth magnets, improves the practicality of the motor, and improves the overall performance of the vehicle.

[0120] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0121] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A rotor assembly (100), characterized in that: include: A rotor core (1), the rotor core (1) being provided with a plurality of first mounting grooves (11), the plurality of first mounting grooves (11) being arranged at intervals along the circumference of the rotor core (1), and a first magnet group (2) being arranged in each of the first mounting grooves (11); The first magnet group (2) comprises a first permanent magnet (21), a second permanent magnet (22) and a third permanent magnet (23); the first permanent magnet (21) and the third permanent magnet (23) are located on both sides of the second permanent magnet (22); the remanence of the second permanent magnet (22) is higher than the remanence of the first permanent magnet (21); the remanence of the second permanent magnet (22) is higher than the remanence of the third permanent magnet (23); and the material of the second permanent magnet (22) is different from the material of the first permanent magnet (21) and the third permanent magnet (23); The width of the second permanent magnet (22) is smaller than the width of the first permanent magnet (21) and the third permanent magnet (23), respectively, wherein the width of the second permanent magnet (22) is in the range of 2.5 mm to 7 mm, and the width of the first permanent magnet (21) and the third permanent magnet (23) is in the range of 5 mm to 12 mm; The rotor core is further provided with a plurality of second mounting grooves (12), the plurality of first mounting grooves (11) and the plurality of second mounting grooves (12) being arranged alternately along the circumferential direction of the rotor core (1), each of the second mounting grooves (12) being provided with a second magnet group (3), the second magnet group (3) comprising a fourth permanent magnet (31), a fifth permanent magnet (32) and a sixth permanent magnet (33), the fourth permanent magnet (31) and the sixth permanent magnet (33) being located in the first permanent magnet group (31), the fifth permanent magnet (32) and the sixth permanent magnet (33) being located in the second permanent magnet group (31). On both sides of the fifth permanent magnet (32), the remanence of the fifth permanent magnet (32) is higher than the remanence of the fourth permanent magnet (31), the remanence of the fifth permanent magnet (32) is higher than the remanence of the sixth permanent magnet (33), the material of the fifth permanent magnet (32) is different from the materials of the fourth permanent magnet (31) and the sixth permanent magnet (33), and the first magnet group (2) and a corresponding group of the second magnet group (3) are symmetrically arranged about the d-axis of the rotor core (1); In the length direction of the first mounting groove (11), the second permanent magnet (22) is located on a side of the first permanent magnet (21) close to the d-axis; On the same cross section of the rotor core (1), the line between the geometric center of the first permanent magnet (21) and the center of the rotor core (1) is a first line, the line between the geometric center of the second permanent magnet (22) and the center of the rotor core (1) is a second line, the line between the geometric center of the third permanent magnet (23) and the center of the rotor core (1) is a third line, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, and the angle between the third line and the d-axis is α3, wherein the rotor assembly (100) satisfies the following relationship:

2. The rotor assembly (100) according to claim 1, characterized in that: The length of the second permanent magnet (22) is respectively greater than the length of the first permanent magnet (21) and the length of the third permanent magnet (23).

3. The rotor assembly (100) according to claim 2, characterized in that: The first mounting groove (11) comprises a first sub-groove (111) and a second sub-groove (112); the width of the first sub-groove (111) is smaller than the width of the second sub-groove (112); the second permanent magnet (22) is placed in the first sub-groove (111); and the first permanent magnet and the third permanent magnet (23) are placed in the second sub-groove (112), respectively.

4. The rotor assembly (100) according to claim 1, characterized in that: The first permanent magnet (21) and the third permanent magnet (23) are respectively ferrite magnets, and the second permanent magnet (22) is rare earth magnets.

5. The rotor assembly (100) according to claim 1, characterized in that: On the same cross section of the rotor core (1), the length of a first line between the geometric center of the first permanent magnet (21) and the center of the rotor core (1) is L1, the length of a second line between the geometric center of the second permanent magnet (22) and the center of the rotor core (1) is L2, and the length of a third line between the geometric center of the third permanent magnet (23) and the center of the rotor core (1) is L3, wherein the rotor assembly (100) satisfies the following relationship:

6. The rotor assembly (100) according to claim 1, characterized in that: On the same cross section of the rotor core (1), the length of a first line between the geometric center of the first permanent magnet (21) and the center of the rotor core (1) is L1, the length of a second line between the geometric center of the second permanent magnet (22) and the center of the rotor core (1) is L2, the width of the first permanent magnet (21) is W1, the width of the second permanent magnet (22) is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, the angle between the third line and the d-axis is α3, and the rotor assembly (100) satisfies the following relationship:

7. The rotor assembly (100) according to claim 1, characterized in that: On the same cross section of the rotor core (1), the length of a first line between the geometric center of the first permanent magnet (21) and the center of the rotor core (1) is L1, the length of a third line between the geometric center of the third permanent magnet (23) and the center of the rotor core (1) is L3, the width of the first permanent magnet (21) is W1, the width of the second permanent magnet (22) is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, the angle between the third line and the d-axis is α3, and the rotor assembly (100) satisfies the following relationship:

8. The rotor assembly (100) according to claim 1, characterized in that: On the same cross section of the rotor core (1), the length of a second line between the geometric center of the second permanent magnet (22) and the center of the rotor core (1) is L2, the length of a third line between the geometric center of the third permanent magnet (23) and the center of the rotor core (1) is L3, the width of the first permanent magnet (21) is W1, the width of the second permanent magnet (22) is W2, the angle between the first line and the d-axis is α1, the angle between the second line and the d-axis is α2, the angle between the third line and the d-axis is α3, and the rotor assembly (100) satisfies the following relationship:

9. The rotor assembly (100) according to claim 1, characterized in that: The width of the first permanent magnet (21) is W1, the width of the second permanent magnet (22) is W2, the remanence of the first permanent magnet (21) is Br1, the remanence of the second permanent magnet (22) is Br2, and the remanence of the third permanent magnet (23) is Br3, wherein Br1=Br3, 10. The rotor assembly (100) according to any one of claims 1 to 9, characterized in that: The coercive force of the first permanent magnet (21) is Hc1, the coercive force of the second permanent magnet (22) is Hc2, the coercive force of the third permanent magnet (23) is Hc3, the width of the second permanent magnet (22) is W2, the width of the third permanent magnet (23) is W3, wherein Hc1=Hc3, Where e is a natural constant.

11. A motor, characterized in that: include: A rotor assembly (100), wherein the rotor assembly (100) is a rotor assembly (100) according to any one of claims 1 to 10; A stator assembly, the stator assembly cooperates with the rotor assembly (100).

12. A vehicle, characterized in that: Comprising an electric machine according to claim 11.

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