Motor rotor, motor, powertrain, and electric vehicle

Abstract

The present application provides a motor rotor, a motor, a powertrain, and an electric vehicle. The motor rotor comprises a rotor core and magnetic assemblies; each magnetic assembly comprises n magnetic unit pairs arranged at intervals in the circumferential direction of the rotor core; each magnetic unit pair comprises two magnetic units; and each magnetic unit comprises at least one permanent magnet and a permanent magnet slot arranged in one-to-one correspondence with the at least one permanent magnet, the permanent magnet slot being arranged in the rotor core, and each permanent magnet being arranged in the corresponding permanent magnet slot. The at least one permanent magnet has a first surface and a second surface that are disposed opposite to each other in the magnetization direction of the at least one permanent magnet. In at least some magnetic units, the first surface and / or the second surface of the at least one permanent magnet is configured as an arc-shaped profiled surface. The arc-shaped profiled surface has at least one arc-shaped surface, and a protrusion is formed at the position of the at least one arc-shaped surface. The motor rotor provided in the present application can reduce motor noise and improve the riding comfort of a passenger in the electric vehicle.

Description

Motor rotor, motor, powertrain and electric vehicle

[0001] This application claims priority to Chinese Patent Application No. 202422120615.X, filed on August 29, 2024, entitled "Electric Motor Rotor, Electric Motor, Powertrain and Electric Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of motor technology, and in particular to a motor rotor, motor, powertrain, and electric vehicle. Background Technology

[0003] With the rapid development of new energy vehicles, new energy powertrain systems have attracted much attention, and permanent magnet synchronous motors are an important component of electric vehicle drive systems.

[0004] A permanent magnet synchronous motor consists of a stator and a rotor connected coaxially. The stator is fitted around the rotor, and the rotating magnetic field of the stator drives the permanent magnets inside the rotor to rotate, thus providing input torque power to the electric vehicle via the motor shaft connected to the rotor. Because there is an air gap between the rotor and stator, the rotor's rotation generates an air gap magnetic field, which in turn produces electromagnetic force waves that vary with time and space—torque pulsations. These electromagnetic force waves cause the stator to vibrate, which in turn causes vibrations in the surrounding air, generating electromagnetic noise. This electromagnetic noise is transmitted to the passenger compartment through the vehicle's structural path and the air path, affecting the passenger experience. Some existing technologies use methods such as fine-tuning the air gap shape and thickening the stator yoke to reduce electromagnetic noise, but the noise reduction effect is limited and the cost is high.

[0005] It is evident that the electromagnetic noise of motors in existing technologies is significant, affecting the comfort of electric vehicle passengers. Summary of the Invention

[0006] This application provides a motor rotor, a motor, a powertrain, and an electric vehicle, which solves the problem of high electromagnetic noise in existing motors affecting the comfort of electric vehicle passengers.

[0007] A first aspect of this application provides a motor rotor, including a rotor core and a magnetic assembly. The magnetic assembly is embedded inside the rotor core, located between its inner and outer wall surfaces. The magnetic assembly includes n pairs of magnetic units spaced apart circumferentially along the rotor core, where n is an integer greater than or equal to 2. Each pair of magnetic units includes two magnetic units, and each magnetic unit includes at least one permanent magnet and a permanent magnet slot corresponding to the at least one permanent magnet. The permanent magnet slots are disposed in the rotor core, and each permanent magnet is disposed in its corresponding slot.

[0008] In this embodiment, at least one permanent magnet has a first surface and a second surface disposed opposite to each other along its magnetization direction, and in at least a portion of the magnetic units, the first surface and / or the second surface of at least one permanent magnet is configured as an arc-shaped surface, the arc-shaped surface having at least one arc-shaped surface and a protrusion formed at the location of at least one arc-shaped surface.

[0009] In the motor rotor provided in this application, at least a portion of the permanent magnets have a first surface and a second surface arranged opposite to each other along their magnetization direction. The magnetization direction is the direction of the magnetic field of the permanent magnet, determining its N pole (north pole) and S pole (south pole). The first and second surfaces correspond to the two magnetization directions of the permanent magnet. At least one of the first and second surfaces is used as a curved surface, which has an arc shape and protrusions at the location of the arc shape. On one hand, the arc shape can change the magnetic flux direction of the permanent magnet, thereby changing the air gap magnetic field between the rotor and stator, reducing torque pulsation, i.e., reducing the fluctuation of electromagnetic force as the rotor rotates. Furthermore, the vibration of the motor stator and the vibration of the air around the motor are weakened, thereby reducing electromagnetic noise. On the other hand, the arc shape on the surface of the permanent magnet increases the design parameters of the motor. During the motor design process, the shape, size, number, curvature, and other parameters of the arc shape can be flexibly adjusted to continuously optimize the motor until the ideal noise reduction effect is achieved.

[0010] As can be seen, the motor rotor provided in this application embodiment can reduce motor noise and improve the comfort of electric vehicle passengers.

[0011] In one possible implementation, the ratio of the thickness of each protrusion on the curved surface to the minimum thickness of the permanent magnet to which it is located is less than or equal to 0.5, where the minimum thickness of the permanent magnet is the minimum distance between the first and second surfaces along its magnetization direction.

[0012] By adopting the above solution, the amount of permanent magnets can be reduced while ensuring noise reduction, thereby reducing the production and processing costs of the motor.

[0013] In one possible implementation, the projection of each arcuate surface of the curved surface onto the first plane is a circular arc, an elliptical arc, or a quadratic curve. The first plane is perpendicular to the axis of the rotor core.

[0014] Using the above scheme, each arc surface of the curved surface can be a circular arc surface, an elliptical arc surface, or a quadratic surface. These shapes are relatively regular and have low design and processing difficulty.

[0015] In one possible implementation, the curved surface has an arc-shaped surface at both ends along its curvature direction, which are respectively connected to the two sides of the permanent magnet on which it is located, and the protrusion formed at the position of the arc-shaped surface is an arc-shaped protrusion.

[0016] In one possible implementation, at least one permanent magnet of the magnetic unit includes two first permanent magnets arranged symmetrically in a V-shape along the centerline of the magnetic unit. The first surface and / or the second surface of the first permanent magnets are configured as curved surfaces.

[0017] In one possible implementation, the relationship between the thickness of each protrusion on the curved surface of the first permanent magnet and the corresponding minimum thickness of the first permanent magnet satisfies: 0.1H11≤H12≤0.4H11, where H12 is the thickness of the protrusion and H11 is the corresponding minimum thickness of the first permanent magnet. This range is an empirical value calculated by simulation and can achieve a good noise reduction effect.

[0018] In one possible implementation, the magnetic unit with the first permanent magnet further includes two second permanent magnets arranged symmetrically in a V-shape along the corresponding centerline of the magnetic unit, and along the centerline of the magnetic unit, the second permanent magnets are disposed on the side of the first permanent magnet facing the inner wall surface of the rotor core. The first surface and / or the second surface of the second permanent magnet are configured as curved surfaces.

[0019] In one possible implementation, the relationship between the thickness of each protrusion on the curved surface of the second permanent magnet and the corresponding minimum thickness of the second permanent magnet satisfies: H22 ≤ 0.1H21, where H22 is the thickness of the protrusion and H21 is the corresponding minimum thickness of the second permanent magnet. This range is an empirical value obtained through simulation and can achieve a good noise reduction effect.

[0020] In one possible implementation, each permanent magnet slot has a first slot wall and a second slot wall spaced apart along the magnetization direction of the corresponding permanent magnet, the gap between the first slot wall and the first surface of the permanent magnet is less than 0.1 mm, and the gap between the second slot wall and the second surface of the permanent magnet is less than 0.1 mm.

[0021] With the above solution, it is understood that the groove wall and the surface of the permanent magnet are fitted with a gap. When the first surface and / or the second surface are set as curved surfaces, the corresponding first groove wall and / or the second groove wall are also set as corresponding curved surfaces, so that the permanent magnet can be smoothly installed into the corresponding permanent magnet groove.

[0022] In one possible implementation, at least a portion of the outer wall surface of the rotor core is configured as a curved wall surface, the curved wall surface having at least one arcuate surface and forming a protrusion or depression at the location of at least one arcuate surface.

[0023] By adopting the above scheme, the outer wall surface of the rotor core is curved, which increases the designable parameters of the motor, enabling further optimization of the motor and reduction of noise.

[0024] In one possible implementation, the rotor core comprises a plurality of rotor core segments arranged sequentially along the axis of the rotor core, each rotor core segment having a magnetic component embedded therein. The magnetic components on at least two rotor core segments are staggered circumferentially along the rotor core.

[0025] The second aspect of this application provides an electric motor, including a motor stator and a motor rotor provided by the first aspect and any possible implementation thereof, wherein the motor stator and the motor rotor are coaxially sleeved together.

[0026] The motor provided in this application embodiment has low operating noise, which can reduce the noise in the passenger compartment of the electric vehicle and improve the riding comfort.

[0027] A third aspect of this application provides a powertrain including a gearbox, a drive shaft, and a motor as described in the second aspect above. The gearbox is connected to the motor rotor via the drive shaft.

[0028] The powertrain provided in this application embodiment can reduce noise in the passenger compartment of an electric vehicle and improve passenger comfort.

[0029] A fourth aspect of this application also provides an electric vehicle, including a body, wheels, and the powertrain provided in the third aspect above. The powertrain is disposed on the body and is used to drive the wheels.

[0030] The electric vehicle provided in this application embodiment has low driving noise and high comfort. Attached Figure Description

[0031] Figure 1 is a structural schematic diagram of the electric vehicle according to an embodiment of this application;

[0032] Figure 2 is a structural block diagram of the electric vehicle according to an embodiment of this application;

[0033] Figure 3 is a schematic diagram of the powertrain structure according to an embodiment of this application;

[0034] Figure 4a is a schematic diagram of the structure of the motor according to an embodiment of this application;

[0035] Figure 4b is a schematic diagram of the air gap structure of the motor in an embodiment of this application;

[0036] Figure 5 is a three-dimensional structural diagram of the motor rotor according to an embodiment of this application;

[0037] Figure 6 is an exploded structural diagram of the motor rotor according to an embodiment of this application;

[0038] Figure 7 is a three-dimensional structural diagram of the rotor core segment in the motor rotor of an embodiment of this application;

[0039] Figure 8 is an exploded structural diagram of the rotor core section of the motor in an embodiment of this application;

[0040] Figure 9 is a schematic diagram of the end face structure of the motor rotor according to an embodiment of this application;

[0041] Figure 10 is a schematic diagram of the permanent magnet slot in the motor rotor according to an embodiment of this application;

[0042] Figures 11a to 11f are schematic diagrams of the arc-repaired surface structure of the permanent magnet in the motor rotor according to an embodiment of this application;

[0043] Figure 12 is a side view of the second permanent magnet in the motor rotor according to an embodiment of this application.

[0044] Figures 13a to 13g are schematic diagrams of the layout of permanent magnets in the motor rotor of an embodiment of this application;

[0045] Figure 14a is a schematic diagram of the magnetic field distribution of a permanent magnet in an electric motor;

[0046] Figure 14b is a schematic diagram of the magnetic field distribution of the permanent magnet in the motor according to an embodiment of this application;

[0047] Figure 15a is a simulation diagram of torque pulsation of a motor;

[0048] Figure 15b is a simulation diagram of torque pulsation of the motor in an embodiment of this application;

[0049] Figure 16 shows the noise response curve of the motor.

[0050] Explanation of reference numerals in the attached drawings: 100-Electric vehicle; 11-Body; 12-Wheel; 13-Battery module; 14-Transmission device; 200-Powertrain; 21-Gearbox; 22-Drive shaft; 300-Motor; 3-Motor stator; 31-Base; 32-Stator core; 320-Stator slot; 33-Stator winding; 400-Motor rotor; 4-Rotor core; 40-Inner wall surface; 41-Outer wall surface; 41A-Arched wall surface; 411-Arched surface; 42-Rotor core segment; 5-Magnetic component; 51-Magnetic unit pair; 511-Magnetic unit; 6-Permanent magnet; 61-First permanent magnet; 62-Second permanent magnet; 63-First surface; 64-Second surface; 65-Curved surface; 651-Curved surface; 652-Protrusion; 66-First side surface; 67-Second side surface; 68-Third side surface; 69-Fourth side surface; 7-Permanent magnet slot; 71-First slot wall; 72-Second slot wall; 82-Motor shaft; 83-Shaft cover; M-First plane; O-Axis; Q-Center line; X-Magnetic direction. Detailed Implementation

[0051] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Although the description of this application will be presented in conjunction with some embodiments, this does not mean that the features of this application are limited to this embodiment. On the contrary, the purpose of describing the application in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of this application. To provide a thorough understanding of this application, many specific details will be included in the following description. This application may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of this application, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0052] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0053] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "top," and "bottom," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0055] In the description of this application, it should be noted that the mutual perpendicularity in this application is not absolute perpendicularity. Approximate perpendicularity due to processing errors and assembly errors (e.g., the included angle between two structural features is 89.9°) is also within the scope of mutual perpendicularity in this application. Similarly, the mutual parallelism in this application is not absolute parallelism. Approximate parallelism due to processing errors and assembly errors (e.g., the included angle between two structural features is 0.1°) is also within the scope of mutual parallelism in this application. This application does not impose specific limitations in this regard.

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0057] Most permanent magnet synchronous motors employ an air-gap structure, where an air gap exists between the motor rotor and stator. When the rotor rotates, it generates an air-gap magnetic field, which in turn produces electromagnetic force waves that vary with time and space—namely, torque pulsation. These electromagnetic force waves induce vibrations in the motor stator and housing, which in turn cause vibrations in the surrounding air, generating electromagnetic noise. In electric vehicles, this electromagnetic noise is transmitted to the passenger compartment through the vehicle's structural path and airflow path, affecting the passenger experience. This application provides a motor rotor, a motor, a powertrain, and an electric vehicle to reduce electromagnetic noise and improve passenger comfort.

[0058] The motor provided in this application can be used not only in electric vehicles, but also in mechanical equipment in other fields, such as washing machines, refrigerators, fans or water pumps, etc. This application does not impose any restrictions.

[0059] Please refer to Figures 1 to 3. Figure 1 is a structural schematic diagram of the electric vehicle according to an embodiment of this application; Figure 2 is a structural block diagram of the electric vehicle according to an embodiment of this application; and Figure 3 is a structural schematic diagram of the powertrain according to an embodiment of this application.

[0060] As shown in Figures 1 to 3, this application provides an electric vehicle 100, which is a new energy vehicle powered by electric drive. The electric vehicle 100 can be a pure electric vehicle or a hybrid vehicle combining hydrogen, fuel, or other fuels with electricity; this application does not impose any limitations on this. The electric vehicle 100 includes a body 11, wheels 12, and a powertrain 200. The powertrain 200 is mounted on the body 11 and drives the wheels 12. In one possible implementation, the electric vehicle 100 may further include a transmission device 14 and a battery module 13, with the wheels 12 connected to the powertrain 200 via the transmission device 14. In another possible implementation, the battery module 13 is fixed to the body 11 and supplies power to the powertrain 200.

[0061] The specific structure of the powertrain 200 is not limited. In one possible implementation, the powertrain 200 includes a gearbox 21, a drive shaft 22, and a motor 300. The gearbox 21 is connected to the stator and rotor 400 of the motor 300 via the drive shaft 22. Exemplarily, the driving force output by the motor 300 can be transmitted to the gearbox 21 via the drive shaft 22. The gearbox 21 is connected to the wheels 12 via a transmission device 14. The gearbox 21 can change the driving force according to different driving conditions of the electric vehicle 100, driving the wheels 12 to rotate at different speeds, thereby realizing the variable speed driving of the electric vehicle 100.

[0062] In one possible implementation, the powertrain 200 may further include a motor controller (not shown in the figure), which receives DC power from the battery module 13 and converts it into AC power to be supplied to the motor 300. The motor 300 receives the AC power, converts the electrical energy into mechanical energy, and transmits the mechanical energy to the gearbox 21. In practical scenarios, the powertrain 200 of the electric vehicle 100 may include more or fewer structures than those shown in the figures, and this application does not impose any limitations on this.

[0063] Please refer to Figures 4a and 4b. Figure 4a is a schematic diagram of the structure of the motor in the embodiment of this application; Figure 4b is a schematic diagram of the air gap structure of the motor in the embodiment of this application.

[0064] As shown in Figures 4a and 4b, the motor 300 includes a motor stator 3 and a motor rotor 400, which are coaxially mounted. Specifically, the motor 300 may also include a motor shaft 82, with the motor rotor 400 mounted on and fixed relative to the motor shaft 82, and the motor stator 3 mounted outside the motor rotor 400. As shown in Figure 4b, there is an air gap between the motor rotor 400 and the motor stator 3, or in other words, a gap between them. When the motor 300 is working, the motor stator 3 applies a rotating magnetic field to the motor rotor 400, causing the motor rotor 400 to rotate relative to the motor stator 3, which in turn drives the motor shaft 82 to rotate. The motor 300 outputs power through the motor shaft 82. For example, the motor shaft 82 can be connected to a transmission shaft 22 to transmit power to the gearbox 21. The transmission shaft 22 can also be understood as the input shaft of the gearbox 21.

[0065] It should be noted that the specific structure of the motor stator 3 is not limited. As shown in Figures 4a and 4b, in one possible implementation, the motor stator 3 includes a base 31, a stator core 32, and a stator winding 33. The stator core 32 is part of the motor's magnetic circuit and is mainly composed of stacked annular laminations such as silicon steel sheets. The stator winding 33 is installed inside the stator core 32 and is a component of the motor 300's circuitry. Specifically, the stator winding 33 is a coil structure wound on the stator core 32; passing alternating current through the stator winding 33 generates a rotating magnetic field. The base 31 is used to mount and fix the stator core 32 and the stator winding 33, and can be considered as the housing of the motor 300.

[0066] As shown in Figure 4b, in one possible implementation, the stator core 32 includes a plurality of stator slots 320 arranged circumferentially. These slots 320 are closely spaced, serrated protrusions used to enhance the stability of the magnetic field of the motor 300. Furthermore, the stator slots 320 also help the motor 300 control its speed and adjust its output power. It should be noted that the specific number of stator slots 320 is not limited and can be designed and optimized according to parameters such as the dimensions of the motor 300. In one possible implementation, the motor stator 3 has 54 stator slots 320.

[0067] The stator slots 320 are a crucial structural element of the motor 300, but they are also a source of noise. As those skilled in the art will understand, the torque pulsation of the motor 300 primarily consists of ripple torque and cogging torque. Ripple torque is the torque generated by harmonics in the air gap magnetic flux density. As the rotational speed of the motor rotor 400 increases, the high-frequency components of the air gap magnetic flux density waveform also increase, resulting in high-frequency noise. Cogging torque is the torque generated by the periodic interaction between the rotor magnetic field and the stator slots 320. Cogging torque can be measured by the average tooth force of the motor stator 3 (i.e., the average electromagnetic force experienced by the stator slots 320 during motor 300 operation). The greater the average tooth force, the greater the cogging torque, and the greater the torque pulsation. By rationally designing the parameters of the motor 300, the cogging torque and ripple torque can be reduced, as well as the harmonic magnetic field of the air gap magnetic field, thereby reducing torque pulsation and lowering the operating noise of the motor 300.

[0068] It should be noted that Figures 4a and 4b are merely illustrative and do not limit the specific shape and structure of the motor 300. In other possible embodiments, the motor 300 may include more or fewer structures than shown in the figures.

[0069] Please refer to Figures 5 to 10. Figure 5 is a three-dimensional structural schematic diagram of the motor rotor of the embodiment of this application; Figure 6 is an exploded structural schematic diagram of the motor rotor of the embodiment of this application; Figure 7 is a three-dimensional structural schematic diagram of the rotor core segment of the motor rotor of the embodiment of this application; Figure 8 is an exploded structural schematic diagram of the rotor core segment of the motor rotor of the embodiment of this application; Figure 9 is a schematic diagram of the end face structure of the motor rotor of the embodiment of this application; and Figure 10 is a structural schematic diagram of the permanent magnet slot in the motor rotor of the embodiment of this application.

[0070] As shown in Figures 5 and 6, the motor rotor 400 includes a rotor core 4 and a magnetic component 5. The magnetic component 5 is embedded inside the rotor core 4, located between its inner wall surface 40 and outer wall surface 41. Understandably, the rotor core 4 is sleeved outside the motor shaft 82; therefore, the rotor core 4 has a ring-shaped structure, and the inner wall surface 40 and outer wall surface 41 of the rotor core 4 are the inner and outer wall surfaces of this ring-shaped structure. In one possible implementation, the motor rotor 400 also includes two shaft covers 83, which are respectively disposed at both ends of the rotor core 4 along the axis O of the rotor core 4 and sleeved on the motor shaft 82. The shaft covers 83 are used to fix and protect the rotor core 4, preventing damage during rotation. The motor rotor 400 may also omit the shaft covers 83; this application does not impose any restrictions on this.

[0071] In one possible implementation, the rotor core 4 includes multiple rotor core segments 42 arranged sequentially along the axis O of the rotor core 4, each rotor core segment 42 embedding a magnetic component 5. Alternatively, the rotor core 4 can be understood as a segmented structure along the axial direction, with each segment having a corresponding magnetic component 5. The specific number of rotor core segments 42 is not limited. For example, the rotor core 4 illustrated in Figures 5 and 6 includes six rotor core segments 42. In other possible scenarios, the number of rotor core segments 42 can be two, three, eight, etc. Alternatively, the rotor core 4 may not employ a segmented design, i.e., the entire structure may consist of only one rotor core segment 42. Some rotor core segments 42 may not have magnetic components 5, and the structures of the magnetic components 5 within different rotor core segments 42 can be the same or different; this application does not impose any restrictions on this.

[0072] Further, as shown in Figures 7 to 9, the magnetic component 5 includes n magnetic unit pairs 51 arranged circumferentially along the rotor core 4, where n is an integer greater than or equal to 2. Each magnetic unit pair 51 includes two magnetic units 511, and each magnetic unit 511 includes at least one permanent magnet 6 and a permanent magnet slot 7 corresponding to the at least one permanent magnet 6. The permanent magnet slot 7 is disposed in the rotor core 4, and each permanent magnet 6 is disposed in the corresponding permanent magnet slot 7.

[0073] This can be understood as follows: the magnetic component 5 includes n magnetic unit pairs 51 and 2n magnetic units 511. Each magnetic unit 511 has at least one permanent magnet 6, which is installed in a corresponding permanent magnet slot 7. The specific value of n is not limited; for example, it can be 2, 3, or 4. Each magnetic unit 511 can contain one or more permanent magnets 6, and this application does not impose any restrictions on this. For example, the rotor core segment 42 in Figures 7 to 9 has 3 magnetic unit pairs 51 (n = 3), each magnetic unit pair 51 includes 2 magnetic units 511, for a total of 6 magnetic units 511. Each magnetic unit 511 contains 4 permanent magnets 6, and the number of permanent magnet slots 7 corresponds to the number of permanent magnets 6. For example, each rotor core segment 42 of the rotor core 4 can be formed by stacking multiple rotor laminations (e.g., silicon steel sheets), and the rotor laminations have slots. After the rotor laminations are stacked to form the rotor core section 42, these slots form permanent magnet slots 7.

[0074] Understandably, each permanent magnet 6 has an N pole (north pole) and an S pole (south pole). This application does not limit the magnetic pole arrangement of each permanent magnet 6 in the magnetic assembly 5. In one possible implementation, the magnetic pole distribution of two magnetic units 511 within the same magnetic unit pair 51 is different. Therefore, the magnetic assembly 5 cannot be regarded as multiple identical magnetic units 511 arranged along the circumference of the motor stator 3, but rather as multiple magnetic unit pairs 51 arranged along the circumference of the motor stator 3. For example, although the permanent magnets 6 in the two magnetic units 511 of the magnetic unit pair 51 shown in FIG. 7 appear to have the same structure and corresponding positions, the magnetic poles of the two corresponding permanent magnets 6 are set in opposite directions. For example, in the figure, permanent magnet A and permanent magnet A' are in corresponding positions (permanent magnet A' can be regarded as magnet A rotating along the circumference of the rotor core 4), the magnetic pole arrangement of permanent magnet A in the counterclockwise direction is NS, and the magnetic pole arrangement of permanent magnet A' in the counterclockwise direction in the other magnetic unit 511 is SN. It should be noted that the magnetic pole distribution of the permanent magnet 6 in the accompanying drawings is only schematic and does not impose any limitations on the motor rotor 400.

[0075] Further, as shown in Figures 7 and 8, each permanent magnet 6 has a first surface 63 and a second surface 64 disposed opposite to each other along its magnetization direction X. In at least a portion of the magnetic units 511, the first surface 63 and / or the second surface 64 of at least one permanent magnet 6 is configured as an arc-shaped surface 65, the arc-shaped surface 65 having at least one arc-shaped surface 651 and a protrusion 652 formed at the location of at least one arc-shaped surface 651.

[0076] In this context, the magnetization direction X is the magnetic field direction of the permanent magnet 6, determining its N pole (north pole) and S pole (south pole). The first surface 63 and the second surface 64 are the surfaces corresponding to the two magnetization directions of the permanent magnet 6. When the permanent magnet 6 has a block structure, its thickness direction is the magnetization direction X (the thickness direction of each permanent magnet 6 is perpendicular to the axis O of the rotor core 4; in Figure 9, the direction of the thickness H1 of the first permanent magnet 61 is its thickness direction, and the direction of the thickness H2 of the second permanent magnet 62 is its thickness direction).

[0077] In at least a portion of the permanent magnet 6, at least one of the first surface 63 and the second surface 64 is designated as a curved surface 65. The curved surface 65 has an arc-shaped surface 651, and a protrusion 652 is formed at the location of the arc-shaped surface 651. On one hand, providing the arc-shaped surface 651 can change the magnetic flux direction of the permanent magnet 6, thereby altering the air gap magnetic field between the rotor and stator, reducing torque pulsation, i.e., reducing the fluctuation of electromagnetic force as the rotor rotates. Furthermore, the vibration of the motor stator 3 and the vibration of the air surrounding the motor 300 are weakened, thereby reducing electromagnetic noise. On the other hand, the curved surface of the permanent magnet 6 increases the design parameters of the motor 300. During the motor design phase, the shape, size, number, curvature, and other parameters of the arc-shaped surface 651 can be flexibly adjusted to continuously optimize the motor 300 until the ideal noise reduction effect is achieved. Therefore, the motor rotor 400 provided in this embodiment can reduce the electromagnetic noise of the motor and improve the comfort of the vehicle occupants.

[0078] It should be noted that any permanent magnet 6 on any rotor core segment 42 can be provided with a curved surface 65 or not. This application does not limit the number and position of permanent magnets 6 with curved surfaces 65. In one possible implementation, all permanent magnets 6 in the rotor core 4 are provided with curved surfaces 65, which can uniformly change the overall magnetic field distribution of the rotor core 4. Moreover, the curved surface 65 of each permanent magnet 6 increases the designable parameters of the motor 300, achieving better noise reduction. Among the permanent magnets 6, the first surface 63 can be set as the curved surface 65, the second surface 64 can be set as the curved surface 65, or both surfaces can be set with curved surfaces 65. This application does not limit this. As shown in Figures 7 and 8, in one possible implementation, the first surface 63 of each permanent magnet 6 is set as the curved surface 65. The first surface 63 is the surface of each permanent magnet 6 facing the outer wall 41. This can also be understood as setting the surface of each permanent magnet 6 facing the motor stator 3 as the arc-shaped surface 65.

[0079] As shown in Figures 9 and 10, in one possible implementation, each permanent magnet slot 7 has a first slot wall surface 71 and a second slot wall surface 72 spaced apart along the magnetization direction X of the corresponding permanent magnet 6. The gap between the first slot wall surface 71 and the first surface 63 of the permanent magnet 6 is less than 0.1 mm, and the gap between the second slot wall surface 72 and the second surface 64 of the permanent magnet 6 is less than 0.1 mm. Understandably, the slot wall surfaces and the surfaces of the permanent magnet 6 are fitted with a clearance. When the first surface 63 and / or the second surface 64 is set as an arc-shaped surface 65, the corresponding first slot wall surface 71 and / or the second slot wall surface 72 is also set as a corresponding arc-shaped surface, allowing the permanent magnet 6 to be smoothly installed into the corresponding permanent magnet slot 7. In some possible implementations, the gap between the first slot wall surface 71 and the first surface 63 of the permanent magnet 6 can be greater than or equal to 0.1 mm, and the gap between the second slot wall surface 72 and the second surface 64 of the permanent magnet 6 can also be greater than or equal to 0.1 mm; this application does not impose any limitations on this.

[0080] It should be noted that this application does not limit the specific shape or size of the curved surface 65. Several possible scenarios are illustrated below.

[0081] Please refer to Figures 11a to 12. Figures 11a to 11f are schematic diagrams of the arc-repaired surface structure of the permanent magnet in the motor rotor of the present application embodiment; Figure 12 is a side view schematic diagram of the second permanent magnet in the motor rotor of the present application embodiment.

[0082] As shown in Figures 11a to 11c and Figure 12, in one possible implementation, the curved surface 65 has an arc-shaped surface 651. As shown in Figures 11a, 11b, and 12, in one possible implementation, the two ends of the arc-shaped surface 651 along its bending direction are respectively connected to the two sides of the permanent magnet 6, and the protrusion 652 formed at the position of the arc-shaped surface 651 is an arc-shaped protrusion. Specifically, the permanent magnet 6 has a first side surface 66 and a second side surface 67 arranged opposite to each other in its length direction, and a third side surface 68 and a fourth side surface 69 arranged opposite to each other in its width direction. The length direction of each permanent magnet 6 is perpendicular to the axis O of the rotor core 4, and the width direction is parallel to the axis O of the rotor core 4. For example, as shown in Figures 8, 9, and 11a, the length direction of the first permanent magnet 61 is the direction of its length L11, which is perpendicular to the axis O; the width direction of the first permanent magnet 61 is the direction of its width L12, which is parallel to the axis O. The length direction of the second permanent magnet 62 is the direction of its length L21, which is perpendicular to the axis O. Its width direction is the direction of its width L22, which is parallel to the axis O. In one possible implementation, the two ends of the arc-shaped surface 651 along its curvature direction are respectively connected to the two sides of the permanent magnet 6 along its length direction, namely the first side 66 and the second side 67. In some possible implementations, the two ends of the arc-shaped surface 651 along its curvature direction may also be connected to the third side 68 and the fourth side 69; this application does not limit this. As shown in Figure 11c, in one possible implementation, the two ends of the arc-shaped surface 651 along its curvature direction may not be connected to both sides of the permanent magnet 6, or may only be connected to one side; this application does not limit this.

[0083] As shown in Figures 11e and 11f, the curved surface 65 can also have multiple curved surfaces 651, such as two. The multiple curved surfaces 651 can be arranged adjacently, as shown in Figure 11f, or they can be arranged at intervals, as shown in Figure 11e.

[0084] As shown in Figures 11a to 11c, in one possible implementation, the projection of each arcuate surface 651 of the curved surface 65 onto the first plane M is a circular arc, an elliptical arc, or a quadratic curve. The first plane M is perpendicular to the axis O of the rotor core 4. Alternatively, each arcuate surface 651 of the curved surface 65 can be a circular arc, an elliptical arc, or a quadratic surface. These shapes are relatively regular and easier to design and manufacture. In other alternative embodiments, the arcuate surface 651 of the curved surface 65 can also be an irregular arcuate surface 651 or an approximate arcuate surface 651, etc., and this application does not impose any limitations on this. For example, the arcuate surface 651 in Figure 11d includes a straight surface and two curved surfaces connected to the two ends of the straight surface, the straight surface and the two curved surfaces together forming a shape approximating an arcuate surface 651. It is understood that the shape of the arcuate surface 651 of the curved surface 65 can be determined according to actual needs, and this application does not impose any limitations on this.

[0085] As shown in Figures 11a and 12, in one possible implementation, the ratio of the thickness of the protrusion 652 on the curved surface 65 to the minimum thickness of the permanent magnet 6 is less than or equal to 0.5, for example, 0.1, 0.2, 0.35, 0.5, etc. The minimum thickness of the permanent magnet 6 is the minimum distance between the first surface 63 and the second surface 64 along its magnetization direction X, for example, the height of the sidewall of the permanent magnet 6. Specifically, in Figure 11a, the minimum thickness of the permanent magnet 6 is H11, and the thickness of the protrusion 652 is H12, where H1 = H11 + H12, and H12 ≤ 0.5H11. In Figure 12, the minimum thickness of the permanent magnet 6 is H21, and the thickness of the protrusion 652 is H22, where H2 = H21 + H22, and H22 ≤ 0.5H21.

[0086] When the ratio of the thickness of the protrusion 652 at the location of the arc-reducing surface 65 to the minimum thickness of the permanent magnet 6 is less than 0.5, the amount of permanent magnet 6 can be reduced while ensuring noise reduction. Understandably, in the prior art, the permanent magnet 6 has a cuboid structure with two planar surfaces in the magnetization direction X (refer to Figure 14a). Compared to traditional solutions, this application sets an arc-reducing surface 65 on the permanent magnet 6 and controls the ratio of the thickness of the protrusion 652 at the location of the arc-reducing surface 65 to the minimum thickness of the permanent magnet 6 to be below 0.5. This reduces the amount of permanent magnet 6 used (the proportion of permanent magnet 6 in the rotor core 4 is reduced, which can be measured by the cross-sectional area of ​​the permanent magnet 6) while ensuring the same output power and torque, thus reducing the production and processing costs of the motor 300.

[0087] As shown in Figures 7 and 9, in one possible implementation, the magnetic unit 511 includes two first permanent magnets 61, which are arranged symmetrically in a V-shape along the center line Q of the magnetic unit 511. The center line Q of the magnetic unit 511 intersects the axis O of the rotor core 4, dividing the rotor core 4 containing the magnetic unit 511 into two symmetrical parts. Further, the first surface 63 and / or the second surface 64 of the first permanent magnet 61 are configured as curved surfaces 65. In one possible embodiment, the first surface 63 of the first permanent magnet 61 is configured as a curved surface 65, facing the outer wall surface 41 of the rotor core 4, i.e., facing the motor stator 3. In some possible implementations, the second surface 64 of the first permanent magnet 61 may also be configured as a curved surface 65, or both surfaces may be configured as curved surfaces 65; this application does not limit this.

[0088] As shown in Figure 11a, in one possible implementation, the relationship between the thickness H12 of each protrusion 652 on the curved surface 65 of the first permanent magnet 61 and the corresponding minimum thickness H11 of the first permanent magnet 61 satisfies: 0.1H11≤H12≤0.4H11, that is, the ratio of H12 to H11 is in the range of 0.1 to 0.4. This range is an empirical value calculated by simulation and can achieve a good noise reduction effect.

[0089] As shown in Figures 7 and 9, in one possible implementation, the magnetic unit 511 with the first permanent magnet 61 further includes two second permanent magnets 62. The two second permanent magnets 62 are arranged symmetrically in a V-shape along the center line Q of the corresponding magnetic unit 511, and along the center line Q of the magnetic unit 511, the second permanent magnets 62 are located on the side of the first permanent magnet 61 facing the inner wall surface 40 of the rotor core 4. Further, the first surface 63 and / or the second surface 64 of the second permanent magnet 62 are configured as curved surfaces 65. In one possible implementation, the first surface 63 of the second permanent magnet 62 is configured as a curved surface 65, and the first surface 63 faces the outer wall surface 41 of the rotor core 4, that is, towards the motor stator 3. It can be understood that the first permanent magnet 61 and the second permanent magnet 62 in the magnetic unit 511 form a "double V structure". In the "double V structure", the surface of each permanent magnet 6 facing the outer wall surface 41 of the rotor core 4 is set as a curved surface 65.

[0090] As shown in Figure 12, in one possible implementation, the relationship between the thickness H22 of each protrusion 652 in the curved surface 65 of the second permanent magnet 62 and the minimum thickness H21 of the corresponding second permanent magnet 62 satisfies: H22≤0.1H21. This range is an empirical value calculated by simulation, which can achieve a better noise reduction effect.

[0091] Understandably, the design parameters of the motor 300 include multiple aspects, such as the material and dimensions of each component within the motor 300. Regarding the motor rotor 400, the length, diameter, number of segments, material, permanent magnet 6, and permanent magnet slots 7 of the rotor core 4 are crucial. Specifically, the parameters of the permanent magnet 6 include its distribution within the rotor core 4, the dimensions, material, position, and angle of each permanent magnet 6, while the parameters of the permanent magnet slots 7 are set in conjunction with the permanent magnet 6. Specifically, the permanent magnet 6 can be either a sintered magnet or a bonded magnet, and can be made from materials such as AlNiCo, ferrite, NdFeB, or SmCo. As shown in Figure 9, the dimensions of the permanent magnet 6 can include its length, width, thickness, and angle.

[0092] As shown in Figures 5 and 8, in one possible implementation, the total length of the rotor core 4 is S, the number of segments is x, and the width of the first permanent magnet 61 is L12, where L12 = S / x; or it can be understood that the width of the first permanent magnet 61 is the same as the thickness of the rotor core segment 42. In some possible implementations, the width of the first permanent magnet 61 may also be different from the thickness of the rotor core segment 42, for example, smaller than the thickness of the rotor core segment 42, and this application does not impose any restrictions on this.

[0093] As shown in Figure 9, in one possible implementation, the diameter of the rotor core 4 is D, the length of the first permanent magnet 61 is L11, and the thickness is H1, where 0.1D ≤ L11 ≤ 0.2D, and 0.02D ≤ H1 ≤ 0.04D. In some possible implementations, L11 may be less than 0.1D or greater than 0.2D, and H1 may be less than 0.02D or greater than 0.04D; this application does not impose any restrictions on these aspects.

[0094] As shown in Figures 5 and 8, in one possible implementation, the width of the second permanent magnet 62 is L22, where L22 = S / x, meaning the width of the second permanent magnet 62 is the same as the thickness of the rotor core segment 42. In some possible implementations, the width of the second permanent magnet 62 may differ from the thickness of the rotor core segment 42, for example, it may be smaller than the thickness of the rotor core segment 42. This application does not impose any restrictions on this.

[0095] As shown in Figure 9, the second permanent magnet 62 has a length of L21 and a thickness of H2, where 0.15D≤L21≤0.3D and 0.02D≤H2≤0.04D. In some possible implementations, L21 may be less than 0.15D or greater than 0.3D, and H2 may be less than 0.02D or greater than 0.04D; this application does not impose any restrictions on these aspects.

[0096] In the "double V structure," the two first permanent magnets 61 are symmetrical with respect to the center line Q of the magnetic unit 511, and the two second permanent magnets 62 are also symmetrical with respect to the center line Q. The angle between the length direction of the first permanent magnet 61 and the center line Q is α, and the angle between the length direction of the second permanent magnet 62 and the center line Q is β. In one possible implementation, 30°≤α≤75° and 30°≤β≤75°. In some possible implementations, α and β may also be less than 30° or greater than 75°, and this application does not impose any limitations on this.

[0097] Please refer to Figures 13a to 13g, which are schematic diagrams of the layout of permanent magnets in the motor rotor of the embodiments of this application.

[0098] As shown in Figures 13a and 13b, in one possible implementation, the permanent magnets 6 in the rotor core 4 can also be arranged in a "single V structure," for example, only the first permanent magnet 61 (Figure 13a) or only the second permanent magnet 62 (Figure 13b). As shown in Figures 13c and 13e, the permanent magnets 6 in the rotor core 4 can also be arranged in a "line structure." Figure 13c illustrates five magnetic unit pairs 51, while Figures 13d and 13e illustrate two magnetic unit pairs 51. Furthermore, in Figures 13c and 13d, the magnetization direction X of the permanent magnets 6 is distributed radially along the rotor core 4, i.e., a radial arrangement, while in Figure 13e, the magnetization direction X of the permanent magnets 6 is distributed tangentially along the rotor core 4, i.e., a tangential arrangement. As shown in Figure 13f, the permanent magnets 6 in the rotor core 4 can also be arranged in a mixed manner of "single-line structure" and "single V structure", as shown in Figure 13g. They can also be arranged in a mixed manner of radial and tangential "single-line structure", etc. This application will not list them one by one.

[0099] As shown in Figures 7 and 8, in one possible implementation, at least a portion of the outer wall surface 41 of the rotor core 4 is configured as a curved wall surface 41A. The curved wall surface 41A has at least one arcuate surface 411, and a protrusion (protruding from the outer wall surface 41 of the rotor core) or a recess (recessed within the outer wall surface 41 of the rotor core) is formed at the location of the arcuate surface 411. Understandably, the curved surface on the outer wall surface 41 of the rotor core 4 increases the designable parameters of the motor 300, enabling further optimization of the motor 300 and reducing noise. As shown in Figure 5, in one possible implementation, the outer wall surface 41 of each rotor core segment 42 of the rotor core 4 is configured as a curved wall surface 41A. In some possible implementations, only a portion of the outer wall surface 41 of the rotor core segment 42 may be configured as a curved wall surface 41A. In each rotor core segment 42, all outer wall surfaces 41 along its circumference can be configured as curved wall surfaces 41A, or only some outer wall surfaces 41 can be configured as curved wall surfaces 41A; this application does not impose any restrictions on this. The protrusions in the curved wall surfaces 41A can be arc-shaped surfaces 411, elliptical surfaces, quadratic curve surfaces, or irregular curved surfaces, etc.; this application does not impose any restrictions on this. One or more arc-shaped surfaces 411 can be provided on the curved wall surfaces 41A; this application does not impose any restrictions on this. As shown in Figures 7 and 8, in one possible implementation, multiple arc-shaped surfaces 411 are provided on the curved wall surfaces 41A, and the multiple arc-shaped surfaces 411 form multiple protrusions and multiple recesses arranged in an alternating manner on the outer wall surface 41 of the rotor core. In some possible implementations, all the multiple arc-shaped surfaces on the curved wall surfaces 41A can be protrusions, or all can be recesses; this application does not impose any restrictions on this.

[0100] As shown in Figure 5, in one possible implementation, the magnetic components 5 on at least two rotor core segments 42 are staggered circumferentially along the rotor core 4. That is, the electrode rotor adopts a segmented skewed pole structure, and the different rotor core segments 42 are twisted at a certain angle, which can eliminate unbalanced magnetic pull and low-order noise. In the rotor core 4, any two adjacent rotor core segments 42 can be staggered or aligned; this application does not impose any restrictions on this. Any two adjacent rotor core segments 42 can be twisted clockwise or counterclockwise; this application does not impose any restrictions on this. In one possible implementation, the rotor core 4 includes x rotor core segments 42, the motor stator 3 has m stator slots 320, and the maximum twist angle in the rotor core 4 is γ, where γ = 360 / m or γ = 180 / m. Here, γ can be the twist angle between two adjacent or non-adjacent rotor core segments 42. For example, as shown in Figure 5, the rotor core 4 includes six rotor core segments 42, namely: v1, v2, v3, v4, v5, and v6. These six rotor core segments 42 are twisted in a V-shape (the twisting direction between the three left rotor core segments v1, v2, and v3 is different from the twisting direction between the three right rotor core segments v4, v5, and v6). The twisting angle between v1 and v4 is the largest, denoted as γ. Assuming the motor stator 3 has 54 stator slots 320 (m = 54), then γ = 360 / 54 = 6.67°, or γ = 180 / 54 = 3.34°. In some possible implementations, γ can also be other values, such as 6°, 3°, 7°, etc., and this application does not limit this.

[0101] Please refer to Figures 14a to 16. Figure 14a is a schematic diagram of the magnetic field distribution of a permanent magnet in an electric motor; Figure 14b is a schematic diagram of the magnetic field distribution of a permanent magnet in an electric motor according to an embodiment of this application; Figure 15a is a simulation diagram of torque pulsation of an electric motor; Figure 15b is a simulation diagram of torque pulsation of an electric motor according to an embodiment of this application; Figure 16 is a noise response curve of an electric motor.

[0102] To verify the contribution of the proposed solution to motor noise reduction, simulation experiments and other methods were used to compare the proposed solution with traditional solutions. The experimental data and comparison structure are as follows:

[0103] In this application, the structure of the motor 300 shown in Figures 4a to 5 is designed, wherein the motor stator 3 has 54 teeth, the rotor core 4 has a total length of S = 120 mm, a diameter of D = 135.2 mm, and 6 segments; the first permanent magnet 61 has a width L12 = 20 mm, a length L11 = 17.5 mm, and a thickness H1 = 4.3 mm; the second permanent magnet 62 has a width L22 = 20 mm, a length L21 = 28 mm, and a thickness H2 = 4.1 mm.

[0104] As shown in Figure 14b, based on the above data, the first surface 63 of each permanent magnet 6 is set as a curved surface 65, adopting a circular arc structure, with both ends of the circular arc surface connected to the two side walls of the permanent magnet 6. As shown in Figure 14a, with other parameters unchanged, a control group of the traditional scheme is set up, in which the permanent magnet adopts a cuboid structure and does not have a curved surface. Comparing Figures 14a and 14b, it can be seen that the curved surface changes the magnetic field distribution around the permanent magnet, thus changing the air gap magnetic field between the motor rotor and the motor stator.

[0105] As shown in Figures 15a and 15b, in Figure 15a, the horizontal axis represents the electrical angle (the angle occupied by each magnetic unit pair of the motor on the inner circle of the motor stator), and the vertical axis represents the torque ripple of the conventional solution. In Figure 15b, the electrical angle is represented, and the vertical axis represents the torque ripple of the motor of this application. Comparing Figures 15a and 15b, it can be seen that the torque ripple of the motor of this application is reduced overall compared to the conventional solution.

[0106] As shown in Figure 16, the horizontal axis represents the motor frequency, and the vertical axis represents the noise intensity. The three curves are the noise response simulation curves of the motor in this application, the motor in the traditional scheme, and the noise response simulation curve of the motor tested on a test bench (the test bench test simulates actual working conditions by fixing the motor on a test bench and connecting various instruments and equipment to conduct a comprehensive test and evaluation of the motor). The comparison shows that the overall noise response curve of the motor 300 in this application is lower than that of the traditional scheme.

[0107] As shown in Table 1 below, while ensuring sufficient output torque (the output torque of the motor 300 in this application is greater than that of the conventional solution), the amount of permanent magnets used in the motor rotor 400 of this application is reduced by 1.4%, the average tooth force of the motor stator 3 is reduced by 40.7%, and the torque pulsation is reduced by 31.9%.

[0108] Table 1

[0109] Those skilled in the art will understand that motors are prone to generating noise peaks in the breathing mode (a characteristic inherent to the stator, also known as the 0th-order mode). Tests have shown that when the arc surface 651 of the permanent magnet 6's curved surface 65 is a circular arc surface, it reduces noise radiation at the motor's breathing mode by 5 dBA compared to traditional methods. If the circular arc surface is changed to an elliptical arc surface or a quadratic curve surface, the noise radiation at the motor's breathing mode can be reduced by 6 dBA compared to traditional methods. Furthermore, if a segmented skewed pole design is adopted to segment the rotor core, the noise radiation at the motor's breathing mode can be reduced by an additional 2 dBA on top of the above reductions.

[0110] In summary, the motor rotor 400 of the above embodiment can effectively reduce the electromagnetic noise of the motor, thereby reducing the noise generated by the electric vehicle during operation and improving the comfort of passengers.

[0111] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A motor rotor, characterized in that, It includes a rotor core and a magnetic assembly, wherein the magnetic assembly is embedded inside the rotor core and located between its inner wall and outer wall. The magnetic component includes n pairs of magnetic units spaced apart circumferentially along the rotor core, where n is an integer greater than or equal to 2. Each pair of magnetic units includes two magnetic units, and each magnetic unit includes at least one permanent magnet and a permanent magnet slot that corresponds one-to-one with the at least one permanent magnet. The permanent magnet slot is disposed in the rotor core, and each permanent magnet is disposed in the corresponding permanent magnet slot. Each of the permanent magnets has a first surface and a second surface disposed opposite to each other along its magnetization direction. In at least some of the magnetic units, the first surface and / or the second surface of at least one of the permanent magnets is configured as a curved surface, the curved surface having at least one arcuate surface and a protrusion formed at the position of the at least one arcuate surface.

2. The motor rotor as described in claim 1, characterized in that, The ratio of the thickness of each protrusion on the arc-shaped surface to the minimum thickness of the permanent magnet to which it is located is less than or equal to 0.5, where the minimum thickness of the permanent magnet is the minimum distance between the first surface and the second surface along its magnetization direction.

3. The motor rotor as described in claim 2, characterized in that, The projection of each arc-shaped surface of the curved surface onto the first plane is: a circular arc, an elliptical arc, or a quadratic curve; The first plane is perpendicular to the axis of the rotor core.

4. The motor rotor as described in claim 1, characterized in that, The curved surface has an arc-shaped surface, the two ends of which are connected to the two sides of the permanent magnet along its curvature direction, and the protrusion formed at the position of the arc-shaped surface is an arc-shaped protrusion.

5. The motor rotor as described in any one of claims 1 to 4, characterized in that, The at least one permanent magnet of the magnetic unit includes two first permanent magnets, which are arranged symmetrically in a V-shape along the center line of the magnetic unit. The first surface and / or the second surface of the first permanent magnet are configured as the arc-trimmed surface.

6. The motor rotor as described in claim 5, characterized in that, The relationship between the thickness of each protrusion on the curved surface of the first permanent magnet and the corresponding minimum thickness of the first permanent magnet satisfies: 0.1H11≤H12≤0.4H11, where H12 is the thickness of the protrusion and H11 is the minimum thickness of the corresponding first permanent magnet.

7. The motor rotor as described in claim 5, characterized in that, The magnetic unit having the first permanent magnet further includes two second permanent magnets. The two second permanent magnets are arranged symmetrically in a V-shape along the corresponding center line of the magnetic unit, and along the center line of the magnetic unit, the second permanent magnets are disposed on the side of the inner wall surface of the first permanent magnet facing the rotor core. The first and / or second surfaces of the second permanent magnet are configured as the arc-trimmed surfaces.

8. The motor rotor as described in claim 7, characterized in that, The relationship between the thickness of each protrusion on the curved surface of the second permanent magnet and the corresponding minimum thickness of the second permanent magnet satisfies: H22≤0.1H21, where H22 is the thickness of the protrusion and H21 is the minimum thickness of the corresponding second permanent magnet.

9. The motor rotor as described in any one of claims 1 to 4, characterized in that, Each of the permanent magnet slots has a first slot wall and a second slot wall spaced apart along the magnetization direction of the corresponding permanent magnet. The gap between the first slot wall and the first surface of the permanent magnet is less than 0.1 mm, and the gap between the second slot wall and the second surface of the permanent magnet is less than 0.1 mm.

10. The motor rotor as described in any one of claims 1 to 4, characterized in that, At least a portion of the outer wall surface of the rotor core is configured as a curved wall surface, the curved wall surface having at least one arcuate surface and forming a protrusion or depression at the location of at least one arcuate surface.

11. The motor rotor as described in any one of claims 1 to 4, characterized in that, The rotor core includes a plurality of rotor core segments arranged sequentially along the axis of the rotor core, and each rotor core segment is embedded with a magnetic component; The magnetic components on at least two of the rotor core segments are staggered circumferentially along the rotor core.

12. An electric motor, characterized in that, It includes a motor stator and a motor rotor as described in any one of claims 1 to 11, wherein the motor stator and the motor rotor are coaxially sleeved together.

13. A powertrain, characterized in that, It includes a gearbox, a drive shaft, and a motor as described in claim 12, wherein the gearbox is connected to the motor rotor of the motor via the drive shaft.

14. An electric vehicle, characterized in that, It includes a body, wheels, and a powertrain as described in claim 13, the powertrain being disposed on the body and used to drive the wheels.

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