Rotor assembly for motor, motor, and vehicle

Abstract

A rotor assembly for a motor, a motor, and a vehicle. The rotor assembly comprises a rotor body; the rotor body is provided with p magnetic pole pairs; a first magnet slot group and a second magnet slot group that are sequentially arranged in the radial direction are formed on the rotor body; the first magnet slot group comprises a first magnet slot and a second magnet slot; the minimum central angle formed between the radial outer ends of the first magnet slot and the second magnet slot and the circle center of the rotor body is α1, and α1=(k1×180°) / p. The second magnet slot group comprises a third magnet slot and a fourth magnet slot. The minimum central angle formed between the radial outer ends of the third magnet slot and the fourth magnet slot and the circle center of the rotor body is α2, and α2=(k2×180°) / p. Moreover, K1 and K2 satisfy: 0.3≤k1≤0.35, and 0.55≤k2≤0.65.

Description

Rotor assemblies for electric motors, electric motors, and vehicles

[0001] This application claims priority to Chinese patent application No. 202410519653.4, filed on April 26, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of vehicles, and more particularly to a rotor assembly for an electric motor, an electric motor, and a vehicle. Background Technology

[0003] The rotor structure of an electric motor affects its performance. At high speeds, magnetic field harmonics and magnetic flux density have a more pronounced impact on motor noise and other dynamic performance characteristics. Summary of the Invention

[0004] This disclosure aims to address at least one of the technical problems existing in the related art.

[0005] On the one hand, a rotor assembly for an electric motor is proposed. According to this disclosure, the rotor assembly improves the magnetic flux and magnetic flux density by arranging a third magnet slot, a first magnet slot, and a second magnet slot, which can improve the output power of the motor. In addition, by rationally planning the position angle of the magnet slots α1 and α2, magnetic field harmonics can be reduced, and the electromagnetic performance and NVH performance of the motor can be optimized.

[0006] On the other hand, a motor including the aforementioned rotor assembly is proposed.

[0007] On the other hand, a vehicle including the aforementioned motor is proposed.

[0008] The rotor assembly according to this disclosure includes a rotor body with p magnetic pole pairs. A first group of magnetic slots and a second group of magnetic slots are formed on the rotor body in a radial direction. The first group of magnetic slots includes a first magnetic slot and a second magnetic slot. The minimum central angle formed between the radially outer ends of the first and second magnetic slots and the center of the rotor body is α1, where α1 = (k1 × 180°) / p. The second group of magnetic slots includes a third magnetic slot and a fourth magnetic slot. The minimum central angle formed between the radially outer ends of the third and fourth magnetic slots and the center of the rotor body is α2, where α2 = (k2 × 180°) / p. Furthermore, K1 and K2 satisfy: 0.3 ≤ k1 ≤ 0.35, 0.55 ≤ k2 ≤ 0.65.

[0009] By selecting appropriate values ​​for α1 and α2, the rotor assembly disclosed herein can balance parameters such as magnetic flux density, electromagnetic force, and power factor of the motor, thereby achieving higher efficiency, greater output power, and better dynamic performance. Furthermore, appropriate values ​​for α1 and α2 can effectively reduce magnetic field harmonics, thereby reducing motor vibration and noise and improving the motor's NVH performance.

[0010] According to some embodiments of this disclosure, in the first magnet slot group, a first gap is formed between the first magnet slot and the second magnet slot, and the first gap gradually increases in a radially outward direction. In the second magnet slot group, a second gap is formed between the third magnet slot and the fourth magnet slot, and the second gap gradually increases in a radially outward direction.

[0011] According to some embodiments of this disclosure, the rotor assembly further includes: a first magnet and a second magnet, the first magnet and the second magnet being respectively housed within the first magnet slot and the second magnet slot. In the cross-section of the rotor body, the angle between the radially outer edge of the first magnet and the radially outer edge of the second magnet is α3, α3 = k3 × α1, and satisfies: 5 ≤ k3 ≤ 6. The rotor assembly further includes: a third magnet and a fourth magnet, the third magnet and the fourth magnet being respectively housed within the third magnet slot and the fourth magnet slot. In the cross-section of the rotor body, the angle between the radially outer edge of the third magnet and the radially outer edge of the fourth magnet is α4, α4 = k4 × α2, and satisfies: 2 ≤ k4 ≤ 3.

[0012] According to some embodiments of this disclosure, k2 satisfies 0.58≤k2≤0.6; and k1 satisfies 0.32≤k1≤0.34.

[0013] According to some embodiments of this disclosure, the radial outer edge of the rotor body is formed with a rotor auxiliary groove that opens radially outward.

[0014] According to some embodiments of this disclosure, the central angle formed by the two ends of the rotor auxiliary groove in the circumferential direction and the center of the rotor body is β, and satisfies: 1°≤β≤2°.

[0015] According to some embodiments of this disclosure, the first magnet slot group and the second magnet slot group are respectively symmetrically arranged about the d-axis, and the angle between the straight line passing through the center of the auxiliary slot along the radial direction of the rotor body and the d-axis is γ, and satisfies: 0.7×α2≤γ≤0.75×α2.

[0016] According to some embodiments of this disclosure, the radial depth of the rotor auxiliary groove is L1, and satisfies: 0.3mm≤L1≤1mm.

[0017] According to some embodiments of this disclosure, the rotor auxiliary groove is constructed as an arc groove.

[0018] According to some embodiments of this disclosure, the second magnet slot group further includes a plurality of fifth magnet slots located between the third magnet slot and the fourth magnet slot. The lengths of the magnets in the third magnet slot and the fourth magnet slot in the extension direction of the third magnet slot are both L2, and the lengths of the magnets in the fifth magnet slots are L3, satisfying: 1.9 ≤ L2 / L3 ≤ 2.5.

[0019] According to some embodiments of this disclosure, a first connection portion is formed between two adjacent fifth magnet slots in the plurality of fifth magnet slots.

[0020] According to some embodiments of this disclosure, the rotor body forms a second connecting portion between the third magnet slot and the fifth magnet slot adjacent to the third magnet slot in the plurality of fifth magnet slots, and the rotor body forms a third connecting portion between the fourth magnet slot and the fifth magnet slot adjacent to the fourth magnet slot in the plurality of fifth magnet slots.

[0021] The following is a brief description of the motor according to this disclosure.

[0022] The motor according to this disclosure includes the rotor assembly in the above embodiments. Since the motor according to this disclosure is provided with the rotor assembly in the above embodiments, when the motor is equipped with the rotor assembly in the above embodiments, the output power of the motor can be increased by increasing the magnetic flux and magnetic flux density, and the electromagnetic performance and NVH performance of the motor can be optimized by reducing magnetic field harmonics, thereby improving the service life of the motor.

[0023] According to some embodiments of this disclosure, the motor further includes: a stator disposed on the outer periphery of the rotor assembly, an air gap being formed between the stator and the rotor body, the air gap being d1 in the radial direction and satisfying: 1.5mm≤d1≤3mm.

[0024] According to some embodiments of this disclosure, the stator is provided with a plurality of stator slots arranged at intervals in the circumferential direction, and each of the plurality of stator slots is provided with a flat wire winding.

[0025] According to some embodiments of this disclosure, the flat wire windings in each stator slot are configured as at least 10 layers.

[0026] According to some embodiments of this disclosure, the inner circumference of the stator is provided with a plurality of teeth arranged at intervals in the circumferential direction, a stator groove is formed between two adjacent teeth in the plurality of teeth, and a stator auxiliary groove that is recessed in the radial direction is provided on the tooth tip of at least one of the plurality of teeth facing the air gap side.

[0027] According to some embodiments of this disclosure, the width of the stator auxiliary slot is d2, the tooth tip width of the tooth is d3, and satisfies: 1 / 3≤d2 / d3≤1 / 2.

[0028] According to some embodiments of this disclosure, the depth of the stator auxiliary groove in the radial direction is d4, and satisfies: 0.1mm≤d4≤0.3mm.

[0029] According to some embodiments of this disclosure, the rotor has N magnetic poles spaced circumferentially, satisfying: 2≤N≤8, where N is an even number. The stator has N×M stator slots, satisfying: M=3x, where x is a positive integer.

[0030] The following is a brief description of the vehicle according to this disclosure.

[0031] The vehicle according to this disclosure includes the motor described in the above embodiments. Since the vehicle according to this disclosure is equipped with the motor described in the above embodiments, the vehicle's power performance and NVH performance can be effectively improved after the vehicle is equipped with the motor. The motor has high reliability and long service life, which not only improves the reliability of the vehicle but also reduces the cost of replacing and repairing the motor.

[0032] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0033] The above and / or additional aspects and advantages of this disclosure will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0034] Figure 1 is a structural diagram of a rotor assembly according to some embodiments of the present disclosure;

[0035] Figure 2 is a structural diagram of a magnetic pole of a rotor assembly according to some embodiments of the present disclosure;

[0036] Figure 3 is another structural diagram of a magnetic pole of a rotor assembly according to some embodiments of the present disclosure;

[0037] Figure 4 is another structural diagram of a magnetic pole of a rotor assembly according to some embodiments of the present disclosure;

[0038] Figure 5 is a schematic diagram showing the relationship between the motor and rotor assembly according to some embodiments of the present disclosure;

[0039] Figure 6 is a schematic diagram of the relationship between a vehicle and a motor according to some embodiments of the present disclosure;

[0040] Figure 7 shows the relationship between the stress on the second connection (third connection) and L2 / L3;

[0041] Figure 8 shows the relationship between torque pulsation rate and K1 and K2;

[0042] Figure 9 shows the relationship between torque pulsation rate and K3 and K4;

[0043] Figure 10 shows the relationship between torque pulsation rate and β;

[0044] Figure 11 shows the relationship between torque pulsation rate and γ / α2;

[0045] Figure 12 shows the relationship between the air gap width and the area ratio of the magnet.

[0046] Figure 13 shows the relationship between the number of layers in the flat wire winding and eddy current loss.

[0047] Figure 14 shows the relationship between the number of layers in a flat wire winding and its efficiency.

[0048] Figure 15 shows the change of torque over time with and without the stator auxiliary slots open.

[0049] Figure 16 shows the radial pressure variation of the stator at different orders with and without the stator auxiliary slots open.

[0050] Figure 17 shows the changes in average torque and torque pulsation rate for different values ​​of d2 / d3;

[0051] Figure 18 shows the relationship between air gap width and motor power attenuation.

[0052] Figure 19 is a diagram showing the fit between a lower stator and a rotor body according to some embodiments of the present disclosure; and

[0053] Figure 20 is a partial enlarged view of the stator according to some embodiments of the present disclosure.

[0054] Reference numerals: Rotor assembly 1; Rotor body 11; First magnet slot group 12, first magnet slot 121, first magnet 1211, second magnet slot 122, second magnet 1221; Second magnet slot group 13, third magnet slot 131, third magnet 1311, fourth magnet slot 132, fourth magnet 1321, fifth magnet slot 133; First interval 201; Second interval 202; First connecting part 141, second connecting part 142, third connecting part 143; Rotor auxiliary slot 15; Motor 20; Stator 21, teeth 211, stator slot 212, stator auxiliary slot 213; Weight reduction hole 223; Air gap 23, flat wire winding 24, Vehicle 30. Detailed Implementation

[0055] Embodiments of this disclosure are described in detail below, examples of which are illustrated in the accompanying drawings. Throughout the narration, the same or similar reference numerals denote 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 this disclosure, and should not be construed as limiting this disclosure.

[0056] The rotor structure of an electric motor affects its performance. At high speeds, magnetic field harmonics and magnetic flux density have a more pronounced impact on motor noise and other dynamic performance. Therefore, how to reduce motor vibration and noise through structural improvements to the rotor has become a pressing technical problem to be solved in this field.

[0057] The rotor assembly according to some embodiments of the present disclosure is described below with reference to the accompanying drawings.

[0058] In some embodiments of this disclosure, the rotor assembly 1 includes a rotor body 11, which has p magnetic pole pairs. A first magnetic slot group 12 and a second magnetic slot group 13 are formed on the rotor body 11, arranged sequentially in the radial direction. The first magnetic slot group 12 includes a first magnetic slot 121 and a second magnetic slot 122. The minimum central angle formed between the radially outer ends of the first magnetic slot 121 and the second magnetic slot 122 and the center of the rotor body 11 is α1, where α1 = (k1 × 180°) / p. The second magnetic slot group 13 includes a third magnetic slot 131 and a fourth magnetic slot 132. The minimum central angle formed between the radially outer ends of the third magnetic slot 131 and the fourth magnetic slot 132 and the center of the rotor body 11 is α2, where α2 = (k2 × 180°) / p. Furthermore, K1 and K2 satisfy: 0.3≤k1≤0.35, 0.55≤k2≤0.65.

[0059] According to some embodiments of this disclosure, the rotor assembly 1 includes a rotor body 11. A first magnet slot group 12 and a second magnet slot group 13, arranged radially, are machined on the rotor body 11. Each magnet slot group contains different magnet slots, and the number of different magnet slots is not limited. The distribution of the number of magnet slots can be determined according to the actual magnetic flux requirements. For example, the first magnet slot group 12 may contain a first magnet slot 121 and a second magnet slot 122. The second magnet slot group 13 may contain a third magnet slot 131 and a fourth magnet slot 132. Each magnet slot can accommodate a corresponding magnet.

[0060] As shown in Figures 1 and 2, the rotor body 11 has P magnetic pole pairs. A magnetic pole pair can be understood as having two magnetic poles. For any given magnetic pole, the positions of the magnet slots can be rationally planned to optimize the electromagnetic performance of the motor 20. In the first magnet slot group 12, the smallest central angle formed between the radial outer end of the first magnet slot 121 and the radial outer end of the second magnet slot 122 and the center of the rotor body 11 is the first pole arc angle, which can be represented by α1. α1 satisfies: α1 = (k1 × 180°) / p, where 0.3 ≤ k1 ≤ 0.35. For example, if P = 3, that is, when the rotor body 11 has 3 magnetic pole pairs, α1 = k1 × 60°, i.e., 18° ≤ α1 ≤ 21°, where k1 = 0.33. In this case, α1 = 19.8°. Similarly, in the second magnet slot group 13, the smallest central angle formed between the radial outer ends of the third magnet slot 131 and the fourth magnet slot 132 and the center of the rotor body 11 is the second pole arc angle, which can be represented by α2, and α2 satisfies: α2=(k2×180°) / p, where 0.55≤k2≤0.65. For example, if P=3, that is, when the rotor body 11 has 3 pole pairs, α2=k2×60°, that is, 33°≤α1≤39°, where k1=0.59, and at this time, α1=35.4°.

[0061] In the above scheme, during actual processing, k1 and k2 need to be determined to a reasonable value according to actual needs. This can be understood as the design of the first pole arc angle α1 and the second pole arc angle α2 fixing the values ​​of the pole arc angles. This helps to achieve a more stable and consistent magnetic field distribution, enabling the motor 20 to operate efficiently and smoothly. By selecting appropriate values ​​for α1 and α2, parameters such as magnetic flux density, electromagnetic force, and power factor of the motor 20 can be balanced, thereby achieving higher efficiency, greater output power, and better dynamic performance. Appropriate α1 and α2 can also effectively reduce magnetic field harmonics, thereby reducing the vibration and noise of the motor 20 and improving its noise, vibration, and harshness (NVH) performance. Furthermore, fixing the values ​​of α1 and α2 in the production of the motor 20 simplifies the production process and manufacturing flow, reduces manufacturing costs, and also helps to ensure product consistency and reliability.

[0062] As shown in Figure 8, the relationship between torque ripple rate and k1 and k2 is illustrated. It is clear from the figure that when "0.3≤k1≤0.35, 0.55≤k2≤0.65", the torque ripple rate is below 2%. Therefore, the values ​​of α1 and α2 in this case are within a suitable range, which helps to suppress the harmonic content of the magnetic field, improve the NVH performance of the motor, and thus reduce the vibration and noise of the motor.

[0063] In some embodiments, magnetic isolation bridges may be provided between the first magnetic slot 121 and the radial outer edge of the rotor body 11, between the second magnetic slot 122 and the radial outer edge of the rotor body 11, between the third magnetic slot 131 and the radial outer edge of the rotor body 11, and between the fourth magnetic slot 132 and the radial outer edge of the rotor body 11.

[0064] According to some embodiments of this disclosure, as shown in FIG2, a first interval 201 is formed between the first magnet slot 121 and the second magnet slot 122 in the first magnet slot group 12, and the first interval 201 gradually increases in the radially outward direction. A second interval 202 is formed between the third magnet slot 131 and the fourth magnet slot 132 in the second magnet slot group 13, and the second interval 202 gradually increases in the radially outward direction. In the distribution of the two types of magnet slots, the first interval 201 between the first magnet slot 121 and the second magnet slot 122 gradually increases in the radially outward direction, which can also be understood as the distance between the first magnet slot 121 and the second magnet slot 122 gradually increases in the direction away from the center of the rotor body 11. Similarly, the second interval 202 between the third magnet slot 131 and the fourth magnet slot 132 gradually increases in the radially outward direction, which can also be understood as the distance between the third magnet slot 131 and the fourth magnet slot 132 gradually increases in the direction away from the center of the rotor body 11. In this way, the design of the inclined extension of the first magnet groove 121, the second magnet groove 122, the third magnet groove 131 and the fourth magnet groove 132 increases the length of the magnetic flux path compared with the scheme of directly extending radially in related technologies, which can increase the magnetic flux and thus increase the output power of the motor 20.

[0065] According to some embodiments of this disclosure, the rotor assembly 1 further includes a first magnet 1211, a second magnet 1221, a third magnet 1311, and a fourth magnet 1321. The first magnet 1211 and the second magnet 1221 are respectively housed within the first magnet slot 121 and the second magnet slot 122. In the cross-section of the rotor body 11, the angle between the radially outer edge of the first magnet 1211 and the radially outer edge of the second magnet 1221 is α3, where α3 = k3 × α1, and satisfies: 5 ≤ k3 ≤ 6. The third magnet 1311 and the fourth magnet 1321 are respectively housed within the third magnet slot 131 and the fourth magnet slot 132. In the cross-section of the rotor body 11, the angle between the radially outer edge of the third magnet 1311 and the radially outer edge of the fourth magnet 1321 is α4, where α4 = k4 × α2, and satisfies: 2 ≤ k4 ≤ 3.

[0066] It should be noted that fixing the values ​​of the first pole arc angle α1 and the second pole arc angle α2 is equivalent to fixing the radial outer end positions of the first magnet slot 121, the second magnet slot 122, the third magnet slot 131, and the fourth magnet slot 132. However, since the magnet angles between the first magnet 1211 and the second magnet 1221 (e.g., α3) and between the third magnet 1311 and the fourth magnet 1321 (e.g., α4) are still undetermined, it is necessary to rationally plan these magnet angles to improve the performance of the motor 20.

[0067] Here, the magnet angle can refer to the angular distribution of the magnet in the corresponding magnet slot, or the angle at which the magnetic field lines of the magnet spread out. In magnetic materials, the magnetic field distribution and angle of the magnet can affect its magnetic properties, especially in applications such as motors and sensors.

[0068] When rotor assembly 1 operates at high speed, the centrifugal force on the area covered by the magnet slots in each magnetic pole of rotor assembly 1 is proportional to the mass of that area and the square of the radius of rotation. Within a certain range, the larger the magnet angle of each magnet slot group, the larger the span of the corresponding magnet slots. At this time, the area covered by the magnet slot group is also larger, which leads to an increase in the stress on the corresponding magnet slot group covered area. In order to prevent the rotor material from yielding at the limiting speed, it is necessary to increase the thickness of the reinforcing structure on the rotor body 11. However, increasing the thickness of the reinforcing structure will lead to increased magnetic leakage. Therefore, the magnet angle of each magnet slot group needs to be reasonably planned.

[0069] In any magnetic pole, as shown in Figure 3, in the first magnetic slot group 12, the magnetic angle formed between the radial outer edge of the first magnet 1211 and the radial outer edge of the second magnet 1221 is α3, satisfying α3=k3×α1. Here, the radial outer edge can be understood as follows: both the first magnet 1211 and the second magnet 1221 are rectangles, and the edge closest to each other is the radial outer edge, where 5≤k3≤6. For example, when k1=0.33 and α1=19.8°, 99°≤α3≤118.8°. This can be understood as α3 being a multiple of α1 (k3 times), meaning that in the first magnetic slot group 12, the magnetic angle between the first magnet 1211 and the second magnet 1221 can be determined based on the first pole arc angle α1. In this design, if α3 is too large, meaning the magnet angle in the first magnet slot group 12 is too large, it will increase the area occupied by the first magnet slot group 12 in each magnetic pole, thereby increasing the centrifugal force on the corresponding magnet slot group's covered area. If α3 is too small, it will limit the length of the magnetic flux path of the first magnet slot 121 and the second magnet slot 122, reduce the magnetic flux, and increase magnetic field harmonics.

[0070] Similarly, in any magnetic pole, the magnetic angle formed between the radially outer edge of the third magnet 1311 and the radially outer edge of the fourth magnet 1321 in the second magnetic slot group 13 is α4, and satisfies α4=k4×α1. Here, the radially outer edge can be understood as: both the third magnet 1311 and the fourth magnet 1321 are rectangles, and the edge closest to each other is the radially outer edge, where 2≤k4≤3. For example, when k2=0.59 and α2=35.4°, 70.8°≤α4≤106.2°. This can be understood as α4 being a multiple of α2 (k4 times), meaning that in the second magnetic slot group 13, the magnetic angle between the third magnet 1311 and the fourth magnet 1321 can be determined based on the second pole arc angle α2. In this design, if α4 is too large, meaning the magnet angle in the second magnet slot group 13 is too large, it will increase the area occupied by the second magnet slot group 13 in each magnetic pole, thereby increasing the centrifugal force on the corresponding magnet slot group's covered area. If α4 is too small, it will limit the length of the magnetic flux path of the first magnet slot 121 and the second magnet slot 122, reduce the magnetic flux, and increase magnetic field harmonics.

[0071] Furthermore, as shown in Figure 9, the relationship between torque ripple rate and k3 and k4 is illustrated. It is evident from Figure 9 that when 5 ≤ k3 ≤ 6 and 2 ≤ k4 ≤ 3, the torque ripple rate is below 2%. Therefore, the values ​​of α3 and α4 in this case are within a suitable range, which helps to suppress the harmonic content of the magnetic field, improve the NVH performance of the motor, and thus reduce motor vibration and noise.

[0072] In summary, the α3 and α4 design schemes allow for the rational planning of the first magnet slot group 12 and the second magnet slot group 13 in each magnetic pole, enabling more precise adjustment of the magnetic field distribution of the motor 20. This design helps reduce harmonics in the magnetic field, improves the sinusoidal nature of the magnetic field, and thus enhances the NVH performance of the motor 20. Furthermore, the optimized magnetic field distribution also helps improve the torque density and efficiency of the motor 20, thereby improving its overall performance. In addition, this design considers the different characteristics of the first magnet slot group 12 and the second magnet slot group 13, setting different value ranges for k3 and k4 respectively. This differentiated design can better adapt to changes in the internal magnetic field of the motor 20, making the magnetic field more uniform and stable in the radial direction.

[0073] According to some embodiments of this disclosure, k2 satisfies 0.58 ≤ k2 ≤ 0.6, and k1 satisfies 0.32 ≤ k1 ≤ 0.34. Unlike the range of values ​​for k2 and k1 in the above embodiments, some embodiments of this disclosure further restrict the values ​​of k2 and k1. This allows for further optimization of the efficiency, output power, and dynamic performance of the motor 20.

[0074] According to some embodiments of this disclosure, as shown in Figures 2 and 3, a rotor auxiliary slot 15 is formed on the radially outer edge of the rotor body 11, opening radially outward. The rotor auxiliary slot 15 can effectively reduce magnetic field harmonics, which helps to improve the NVH performance of the motor 20. In addition, the rotor auxiliary slot 15 can also increase the heat dissipation area, improve the heat dissipation efficiency of the motor 20, and ensure that the motor 20 can operate stably in harsh environments such as high load and high temperature.

[0075] According to some embodiments of this disclosure, the central angle formed by the lines connecting the two ends of the rotor auxiliary slot 15 in the circumferential direction to the center of the rotor body 11 is β, and satisfies: 1°≤β≤2°. It is understood that the small range of β indicates high precision requirements for the rotor auxiliary slot 15. By setting a high-precision rotor auxiliary slot 15, the performance of the motor 20 can be fine-tuned, further optimizing the electromagnetic performance of the motor 20, such as reducing electromagnetic noise and vibration, thereby improving the overall efficiency and performance of the motor 20. Furthermore, a small-sized rotor auxiliary slot 15 ensures the structural strength of the rotor body 11, preventing the rotor auxiliary slot 15 from being too large and reducing the strength of the rotor body 11, which could lead to damage to the rotor body 11 during high-speed operation.

[0076] As shown in Figure 10, the relationship between torque ripple rate and β is illustrated. It is clear from Figure 10 that when 1°≤β≤2°, the torque ripple rate is below 2%. This helps suppress the harmonic content of the magnetic field, improves the NVH performance of the motor, and thus reduces motor vibration and noise.

[0077] According to some embodiments of this disclosure, as shown in FIG4, the first magnet slot group 12 and the second magnet slot group 13 are symmetrically arranged about the d-axis. The angle between the straight line passing through the center of the rotor auxiliary slot 15 along the radial direction of the rotor body 11 and the d-axis is γ and satisfies: 0.7×α2≤γ≤0.75×α2.

[0078] As shown in Figures 3 and 4, the label 'd' in Figure 4 represents the d-axis. It should be noted that the d-axis is a virtual axis, and the straight line passing through the center of the rotor auxiliary slot 15 is also a virtual line. The d-axis and the straight line passing through the center of the rotor auxiliary slot 15 in Figure 4 are only for convenient labeling and do not represent the actual structure. The first magnet slot group 12 and the second magnet slot group 13 are symmetrical about the d-axis, improving the overall aesthetics of the rotor assembly 1 and ensuring a uniform structural distribution on the rotor assembly 1, avoiding excessively high or low local strength.

[0079] Because the rotor auxiliary slot 15 is relatively small, two symmetrical rotor auxiliary slots 15 can be provided on both sides of the d-axis of the rotor body 11 for any magnetic pole of the rotor. The design of two rotor auxiliary slots 15, compared to a single rotor auxiliary slot 15, improves the heat dissipation effect and further reduces magnetic field harmonics. Furthermore, the symmetry of the two rotor auxiliary slots 15 about the d-axis ensures the balance and stability of the magnetic field of the motor 20. This symmetry helps reduce unbalanced components in the magnetic field, lowers the vibration and noise of the motor 20, and improves the smoothness of motor operation.

[0080] Secondly, as shown in Figure 4, by precisely controlling the angle γ between the center of the rotor auxiliary slot 15 and the d-axis, within the range of 0.7×α² to 0.75×α², a reasonable layout of the rotor auxiliary slot 15 is achieved. If γ is too large, i.e., the rotor auxiliary slot 15 is too far from the d-axis, the adjustment effect of the rotor auxiliary slot 15 on the magnetic field of the motor 20 will be weakened. If γ is too small, i.e., the rotor auxiliary slot 15 is too close to the d-axis, it will affect the setting of the magnetic isolation bridge at the radial outer ends of the first magnetic slot 121, the second magnetic slot 122, the third magnetic slot 131, and the fourth magnetic slot 132. Therefore, setting γ within the range of 0.7×α² to 0.75×α² can further optimize the electromagnetic performance of the motor 20, help adjust the air gap permeability, suppress specific harmonic components in the air gap magnetic flux density, thereby reducing the electromagnetic excitation force and reducing the torque pulsation and vibration of the motor 20.

[0081] Furthermore, as shown in Figure 11, the relationship between torque ripple rate and γ / α2 is illustrated. It is clear from Figure 11 that when 0.7 ≤ γ / α2 ≤ 0.75, the torque ripple rate is below 1.5%, which helps suppress the harmonic content of the magnetic field, improves the NVH performance of the motor 20, and thus reduces the vibration and noise of the motor 20.

[0082] According to some embodiments of this disclosure, the radial depth of the rotor auxiliary groove 15 is L1, and satisfies: 0.3mm ≤ L1 ≤ 1mm. As shown in Figure 4, the radial depth of the rotor auxiliary groove 15 can be represented by L1. If the depth L1 of the rotor auxiliary groove 15 is greater than 1mm, that is, the depth of the rotor auxiliary groove 15 is too deep, it will reduce the structural strength of the rotor body 11. If the depth L1 of the rotor auxiliary groove 15 is less than 0.3mm, that is, the depth of the rotor auxiliary groove 15 is too shallow, it will affect the ability of the rotor auxiliary groove 15 to reduce magnetic field harmonics. Therefore, limiting the depth L1 of the rotor auxiliary groove 15 to the range of 0.3mm to 1mm will not significantly affect the structural strength of the rotor body 11, and can ensure the reliability and durability of the motor 20. In addition, the rotor auxiliary groove 15 within this range has low processing difficulty, which can improve the feasibility and economy of manufacturing the motor 20 while optimizing the electromagnetic performance of the motor 20.

[0083] According to some embodiments of this disclosure, the rotor auxiliary slot 15 is constructed as an arc-shaped slot. Compared to rotor auxiliary slots 15 with shapes other than arc-shaped, the arc-shaped slot can distribute the magnetic field more evenly, reducing harmonic components in the magnetic field, thereby reducing electromagnetic noise and vibration of the motor 20. Furthermore, the arc-shaped rotor auxiliary slot 15 can give the rotor body 11 better mechanical properties, enabling the rotor body 11 to withstand higher stress and impact, which helps to enhance the structural strength of the motor 20 and improve its reliability and durability. In addition, the shape of the arc-shaped slot is relatively simple and easy to manufacture through processes such as machining or casting, reducing the manufacturing cost of the motor 20 and improving production efficiency.

[0084] According to some embodiments of this disclosure, the second magnet slot group 13 further includes a plurality of fifth magnet slots 133 located between the third magnet slot 131 and the fourth magnet slot 132. The lengths of the third magnet 1311 in the third magnet slot 131 and the fourth magnet 1321 in the fourth magnet slot 132 in the extension direction of their respective corresponding magnet slots are L2, and the lengths of the magnets in the fifth magnet slots 133 are L3, and satisfy: 1.9≤L2 / L3≤2.5.

[0085] Based on the polar arc angle and magnet angle in the above embodiments, the relationship between the lengths of the third magnet 1311, the fourth magnet 1321, and the fifth magnet will affect the stress on the area covered by the corresponding magnet groove.

[0086] In some embodiments, a fifth magnet can be disposed within the fifth magnet slot 133, and the lengths of the third magnet 1311, the fourth magnet 1321, and the fifth magnet can satisfy 1.9 ≤ L2 / L3 ≤ 2.5. When L2 / L3 > 2.5, i.e., L2 is too large and L3 is too small, the span between the reinforcing structure at one end of the third magnet slot 131 or the fourth magnet slot 132 and the magnetic isolation bridge at the other end of the corresponding magnet slot will increase, thereby increasing the stress in the area where the magnet slot group is located and affecting the reliability of the rotor assembly 1 during high-speed rotation. When L2 / L3 < 1.9, i.e., L2 is too large and L3 is too small, the mechanical strength distribution of the rotor structure will be uneven. In addition, an excessively large L2 may cause local magnetic circuit saturation, preventing the magnetic flux from effectively passing through the magnets and the air gap, thereby reducing the magnetic energy utilization rate of the motor 20.

[0087] The range of L2 / L3 values ​​can be further defined in Figure 7, which shows the stress distribution of the reinforcing structure between one of the third or fourth magnet slots 131 and the fifth magnet slot 133 when the rotor rotates at 30,000 rpm. As shown in Figure 7, the pattern of the curves is readily apparent: when the sum of L2 and L3 remains constant and the ratio of L2 to L3 is between 1.9 and 2.5, the stress on the reinforcing structure between one of the third or fourth magnet slots 131 and the fifth magnet slot 133 is relatively small. However, when the ratio of L2 to L3 is in other ranges, the stress on the reinforcing structure between one of the third or fourth magnet slots 131 and the fifth magnet slot 133 easily exceeds the yield strength of the rotor material. Therefore, only when the sum of L1 and L2 remains constant and the ratio of L2 to L3 is between 1.9 and 2.5, the thickness of the reinforcing structure between the third magnet slot 131 or the fourth magnet slot 132 and the fifth magnet slot 133 can be appropriately reduced when the motor 20 reaches the same limiting speed. This ensures stable operation of the motor 20 at ultra-high speeds while effectively reducing magnetic leakage and increasing the main magnetic flux content, thereby improving the power density and torque density of the motor 20.

[0088] Therefore, setting L2 / L3 in the range of 1.9 to 2.5 helps to improve the output torque and power density of motor 20, meeting the performance requirements of various application scenarios.

[0089] In some embodiments, a sixth magnet slot may be provided between the first magnet slot 121 and the second magnet slot 122 in the first magnet slot group 12. The arrangement of magnets in the sixth magnet slot can refer to the above embodiments or be determined according to actual needs.

[0090] According to some embodiments of this disclosure, as shown in FIG2, a first connecting portion 141 is formed between two adjacent fifth magnet slots 133.

[0091] In actual processing, a first connecting part 141 can be provided between adjacent fifth magnet slots 133. The provision of the first connecting part 141 can increase the number of reinforcing structures on the rotor body 11, thereby improving the structural strength of the rotor body 11. When the motor 20 reaches the same speed, the thickness of the magnetic isolation bridge can be appropriately reduced to reduce magnetic leakage.

[0092] According to some embodiments of this disclosure, a second connecting portion 142 is formed between the third magnet slot 131 and the fifth magnet slot 133, and a third connecting portion 143 is formed between the fourth magnet slot 132 and the fifth magnet slot 133. The third magnet slot 131, the fourth magnet slot 132, and the fifth magnet slot 133 cooperate to form a U-shaped structure. Compared with the "V"-shaped or "I"-shaped magnet slots in conventional technical solutions, the provision of the second connecting portion 142 and the third connecting portion 143 further increases the number of reinforcing structures on the rotor body 11, improving the overall strength of the rotor body 11. At the limit speed, the thickness of the magnetic isolation bridge can be thinner than in conventional solutions, which can reduce the leakage flux at the magnetic isolation bridge location, thereby further reducing the leakage flux of the motor 20 in the high-speed region and improving the output power of the motor 20 in the high-speed region.

[0093] In some embodiments, a sixth magnetic groove is provided between the first magnetic groove 121 and the second magnetic groove 122. In this case, a fourth connecting part and a fifth connecting part may also be provided between the first magnetic groove 121 and the sixth magnetic groove, and between the second magnetic groove 122 and the sixth magnetic groove.

[0094] The motor 20 according to this disclosure is briefly described below.

[0095] As shown in Figure 5, the motor 20 according to this disclosure includes the rotor assembly 1 in the above embodiments. Since the motor 20 according to this disclosure is provided with the rotor assembly 1 in the above embodiments, when the motor 20 is equipped with the rotor assembly 1 in the above embodiments, not only can the output power of the motor 20 be increased by increasing the magnetic flux and magnetic flux density, but also the electromagnetic performance and NVH performance of the motor 20 can be optimized by reducing magnetic field harmonics, thereby improving the service life of the motor 20.

[0096] According to some embodiments of this disclosure, as shown in Figures 19 and 20, the motor 20 further includes a stator 21 disposed on the outer periphery of the rotor assembly 1. An air gap 23 is formed between the stator 21 and the rotor body 11, the air gap 23 being radially spaced by a distance d1, and satisfying the following condition: 1.5mm ≤ d1 ≤ 3mm.

[0097] According to some embodiments of the present disclosure, the motor 20 defines an air gap 23 between the stator 21 and the rotor body 11. The radial distance of the air gap 23 is d1, and satisfies: 1.5mm ≤ d1 ≤ 3mm. In the industry, the length of the air gap 23 in permanent magnet synchronous motors 20 is generally less than 1.5mm. Compared to related technologies with smaller air gap 23 widths, the motor 20 in some embodiments of the present disclosure increases the width of the air gap 23, which helps to suppress power attenuation and magnetic field harmonics in the high-speed region of the motor 20, thereby improving the efficiency and NVH performance of the motor 20.

[0098] It should be noted that, with the magnetic flux density of the air gap 23 remaining constant, a larger air gap 23 results in greater magnetic reluctance between the stator 21 and the rotor body 11, and a smaller inductance of the motor 20. This leads to an increase in the field weakening current of the motor 20 in the high-speed constant-power region, and consequently, an increase in the output power in the high-speed region. Therefore, a larger air gap 23 helps suppress power attenuation in the high-speed region. The constant magnetic flux density of the air gap 23 can be understood as increasing the amount of permanent magnets to ensure that the magnetic flux density of the air gap 23 is the same as that in related technologies, thus avoiding the negative impacts of changes in magnetic flux density.

[0099] As shown in Figure 12, to maintain a constant magnetic flux density in the air gap 23, the area ratio of the magnets in the rotor body 11 needs to increase with the width of the air gap 23. This can also be understood as follows: when the width of the air gap 23 increases, to maintain a constant magnetic flux density in the air gap 23 and to ensure high power density in the motor 20, the amount of magnets required needs to be increased. When the width of the air gap 23 is greater than 3mm, the required amount of magnets is too large, which is detrimental to the lightweight design of the motor 20.

[0100] The width of the air gap 23 affects the power attenuation of the motor 20 in the high-speed region. Within a certain range, the larger the air gap 23, the smaller the power attenuation; however, increasing the width of the air gap 23 affects the utilization rate of the permanent magnet. Therefore, the width of the air gap 23 needs to be kept within a suitable range. As shown in Figure 18, the width of the air gap 23 and the power attenuation value are roughly linearly related within a certain range. When the width of the air gap 23 is less than 1.5 mm, the power attenuation is relatively large. As the width of the air gap 23 increases, the magnetic reluctance at the air gap 23 position also increases. When the width of the air gap 23 is greater than 3 mm, the magnetic reluctance is too high, and the utilization rate of the permanent magnet is too low. Therefore, keeping the width of the air gap 23 between 1.5 mm and 3 mm can effectively suppress the power attenuation in the high-speed region while ensuring the utilization rate of the permanent magnet.

[0101] When motor 20 operates in the high-speed range, a large amount of eddy current loss is generated in the stator and rotor cores due to the magnetic field. Furthermore, the higher the motor speed and frequency, the greater the eddy current loss in rotor assembly 1. When the width of air gap 23 increases, the harmonic content in the magnetic field of air gap 23 decreases significantly, reducing eddy current loss in rotor assembly 1 during high-speed operation. This improves the rated power and efficiency of motor 20 in the high-speed range. Therefore, increasing the width of air gap 23 can suppress magnetic field harmonics. When the width of the air gap 23 is 1.5mm to 3mm, the large air gap 23 suppresses magnetic field harmonics. Therefore, the torque fluctuation, torque amplitude of each order, and radial electromagnetic force of the motor 20 under maximum load are all at a small level. At this time, the motor 20 can still have good NVH performance even in the case of direct pole. Compared with the traditional solution of using skewed pole to improve NVH performance, the motor 20 in some embodiments of this disclosure not only improves the simplicity of the rotor assembly 1 process, but also reduces the wind friction loss suffered by the rotor assembly 1 when rotating, and further improves the efficiency of the motor 20.

[0102] According to some embodiments of this disclosure, as shown in Figures 19 and 20, the stator 21 is provided with a plurality of stator slots 212 arranged at intervals in the circumferential direction, and flat wire windings 24 are provided in the plurality of stator slots 212.

[0103] For example, the stator 21 has multiple stator slots 212 for assembling windings. These slots are spaced apart circumferentially on the stator 21, and each slot 212 can accommodate a flat wire winding 24. Compared to traditional round wire windings, the gap between the flat wire winding 24 and the stator slot 212 is smaller after assembling the flat wire winding 24. Therefore, assembling the flat wire winding 24 within the stator slot 212 increases the slot fill factor, effectively improving the power density and efficiency of the motor 20.

[0104] According to some embodiments of this disclosure, the flat wire winding 24 in each of the stator slots 212 is configured as at least 10 layers.

[0105] According to some embodiments of this disclosure, the flat wire winding 24 in each stator slot 212 is constructed with at least 10 layers. Compared to the related art scheme using 4 layers of flat wire winding 24, some embodiments of this disclosure assemble at least 10 layers of flat wire winding 24 in each stator slot 212, increasing the number of layers of flat wire winding 24. This effectively reduces eddy current losses in the windings caused by the skin effect when the motor 20 operates in the high-speed range, thereby improving the efficiency and rated power of the motor 20 in the high-speed range. Combined with embodiments that maintain the width of the air gap 23 at 1.5mm to 3mm, some embodiments of this disclosure can comprehensively improve the efficiency and rated power of the motor 20 in the high-speed range to further meet drive requirements.

[0106] As can be seen from Figures 13 and 14, when the number of layers of flat wire winding 24 is increased, the eddy current loss of flat wire winding 24 decreases significantly and the efficiency is slightly improved. Therefore, under the same high-speed operating conditions, the motor 20 with 10 layers of flat wire winding 24 has lower losses than the motor 20 with 4 layers of flat wire winding in related technologies. Under the same heat dissipation conditions, the rated power of the motor 20 with 10 layers of flat wire winding 24 will also be higher.

[0107] According to some embodiments of the present disclosure, the inner circumference of the stator 21 is provided with a plurality of teeth 211 arranged at intervals in the circumferential direction, and a stator groove 212 is formed between two adjacent teeth 211. At least one of the teeth 211 is provided with a stator auxiliary groove 213 that is recessed in the radial direction on the tooth tip facing the air gap 23.

[0108] As shown in Figure 20, the stator 21 is also provided with a plurality of teeth 211 arranged at intervals on its inner circumference. A stator slot 212 is formed between two adjacent teeth 211. The tooth tips of the teeth 211 protrude toward the stator slot 212 on both sides in the circumferential direction, which can improve the assembly stability of the flat wire winding 24. At least one of the teeth 211 has a stator auxiliary slot 213 that is recessed radially at the tooth tip position. The stator auxiliary slot 213 can effectively reduce the magnetic field harmonics of the air gap 23, thereby reducing the torque pulsation and electromagnetic radial force of the motor 20 and improving the NVH performance of the motor 20.

[0109] As shown in Figure 15, the markings 426-435 on the left-hand coordinate axis can be interpreted as torque values. The dashed line represents the torque value over time when the stator 21 has no stator auxiliary slot 213, while the solid line represents the torque value over time after the stator 21 has the stator auxiliary slot 213. It is clear from Figure 15 that when the stator auxiliary slot 213 is installed on the stator 21, the torque fluctuation amplitude is significantly reduced, i.e., the torque pulsation is reduced. This effectively suppresses the tangential electromagnetic force, thereby effectively improving the NVH performance of the motor 20.

[0110] As shown in Figure 16, the radial pressure of the stator 21 under different orders is compared between having the stator auxiliary groove 213 and not having the stator auxiliary groove 213. As can be seen from Figure 16, having the stator auxiliary groove 213 on the stator 21 can effectively reduce the radial pressure of the stator 21 under various orders.

[0111] In some embodiments, the number of stator auxiliary slots 213 can be determined based on parameters such as the actual number of teeth 211 and the number of stator slots 212. For example, in a 6-stage, 72-slot stator 21, each stage has 12 stator slots 212 and 12 teeth 211. Since the motor 20 uses three-phase windings, each phase of the stator 21 has 4 stator slots 212 and 4 teeth 211. In this case, stator auxiliary slots 213 can be provided at the tooth tip positions of two of the four teeth 211, i.e., two stator auxiliary slots 213 are machined. This effectively reduces the harmonics of the magnetic field in the air gap 23 without affecting the structure and other performance characteristics of the motor 20. The arrangement of stator auxiliary slots 213 can be determined based on the actual number of teeth 211 in each phase.

[0112] According to some embodiments of this disclosure, as shown in FIG20, the width of the stator auxiliary groove 213 is d2, the tooth tip width of the tooth portion 211 is d3, and satisfies: 1 / 3≤d2 / d3≤1 / 2.

[0113] In other words, during the machining of the stator auxiliary slot 213, the relationship between the slot width d2 of the stator auxiliary slot 213 and the tooth tip width d3 of the tooth 211 needs to satisfy: 1 / 3 ≤ d2 / d3 ≤ 1 / 2. Here, the slot width can be understood as the width of the stator auxiliary slot 213. It is understood that the stator auxiliary slot 213 effectively reduces magnetic field harmonics and improves the NVH performance of the motor 20. If d2 / d3 < 1 / 3, that is, the slot width of the stator auxiliary slot 213 is too small, the ability of the stator auxiliary slot 213 to reduce magnetic field harmonics will be weakened. If d2 / d3 > 1 / 2, that is, the slot width of the stator auxiliary slot 213 is too large, it will affect the mechanical structural strength of the stator 21. Therefore, d2 / d3 being within the range of 1 / 3 to 1 / 2 allows the stator 21 to effectively reduce magnetic field harmonics while ensuring mechanical structural strength, thereby improving the efficiency and NVH performance of the motor 20.

[0114] As shown in Figure 17, the solid line represents the torque ripple rate as a function of different values ​​of d2 / d3, and the dashed line represents the average torque as a function of different values ​​of d2 / d3. It is clear from Figure 17 that when d2 / d3 is between 1 / 3 and 1 / 2, the torque ripple rate is lower without a significant decrease in average torque. Therefore, keeping d2 / d3 within the range of 1 / 3 to 1 / 2 can improve the NVH performance of motor 20.

[0115] According to some embodiments of this disclosure, as shown in FIG20, the stator auxiliary groove 213 has a radial depth of d4, and satisfies: 0.1mm≤d4≤0.3mm.

[0116] In other words, during the machining of the stator auxiliary slot 213, the depth d4 of the stator auxiliary slot 213 must satisfy: 0.1mm ≤ d4 ≤ 0.3mm. This depth can be understood as the radial depth of the stator auxiliary slot 213. A suitable depth of the stator auxiliary slot 213 helps improve the electromagnetic performance of the motor 20. When d4 < 0.1mm, meaning the depth of the stator auxiliary slot 213 is too shallow, it may not achieve the desired effect, resulting in a weakened ability of the stator auxiliary slot 213 to reduce magnetic field harmonics. Conversely, when d4 > 0.3mm, meaning the depth of the stator auxiliary slot 213 is too deep, it will affect the mechanical structural strength of the stator 21. A slot depth of 0.1mm to 0.3mm can effectively adjust the magnetic field distribution, improve the efficiency and power density of the motor 20, and while ensuring the structural strength of the stator 21, also reduce magnetic field harmonics and improve the NVH performance of the motor 20.

[0117] Furthermore, the arrangement of the stator auxiliary slot 213 is also related to the heat dissipation of the motor 20. When the stator auxiliary slot 213 satisfies the following conditions: 1 / 3 ≤ d2 / d3 ≤ 1 / 2, and 0.1mm ≤ d4 ≤ 0.3mm, the heat dissipation area can be increased, improving the heat dissipation performance of the motor 20. This helps reduce the heat generated by the motor 20 during operation, thereby improving the thermal stability of the motor 20. The depth range of 0.1mm to 0.3mm makes the machining process of the stator auxiliary slot 213 relatively easy to control and also helps to ensure machining accuracy and consistency.

[0118] According to some embodiments of this disclosure, the rotor body 11 has N magnetic poles spaced circumferentially, satisfying: 2≤N≤8, where N is an even number. The stator 21 has N×M stator slots 212, satisfying: M=3x, where x is a positive integer. In some embodiments of this disclosure, the rotor body 11 has N magnetic poles, where N can be any one of 2, 4, 6, or 8. Correspondingly, the number of stator slots 212 is N×M, i.e., 2M, 4M, 6M, or 8M. Since the motor 20 uses three-phase windings, M is a multiple of 3, i.e., M=3x, where x is a positive integer. It can also be understood that the configuration schemes of the rotor body 11 and stator 21 in some embodiments of this disclosure, such as the width of the air gap 23 and the number of layers of the flat wire winding 24, can be used for motors 20 of different specifications, thus having a wide range of applications.

[0119] In some embodiments, the rotor body 11 may also be provided with multiple sets of weight-reducing holes 223. Each set of weight-reducing holes 223 includes one or more weight-reducing holes 223, which can be arranged radially outside the corresponding magnet slot group in each magnetic pole. The arrangement of weight-reducing holes 223 can disperse the stress of the rotor assembly 1 when it rotates at high speed, avoid stress concentration at local positions on the rotor body 11 and damage, and improve the service life and reliability of the rotor assembly 1. Multiple weight-reducing holes 223 can correspond one-to-one with multiple magnetic poles, or multiple weight-reducing holes 223 can correspond to one magnetic pole, as shown in Figure 2. The arrangement of weight-reducing holes 223 and magnetic poles can be determined according to the actual stress distribution.

[0120] The vehicle 30 according to some embodiments of the present disclosure is briefly described below.

[0121] As shown in Figure 6, the vehicle 30 according to this disclosure includes the motor 20 in the above embodiments. Since the vehicle 30 according to some embodiments of this disclosure is equipped with the motor 20 in the above embodiments, the power performance and NVH performance of the vehicle 30 can be effectively improved after the vehicle 30 is equipped with the motor 20. The motor 20 has high reliability and service life, which can not only improve the reliability of the vehicle 30, but also reduce the cost of replacing and repairing the motor 20.

[0122] In the description of this disclosure, it should be understood that the terms “center,” “length,” “width,” “thickness,” “upper,” “lower,” “left,” “top,” “inner,” “outer,” “axial,” “radial,” “circumferential,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure and simplifying the description, and are not intended to 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 of this disclosure.

[0123] In the description of this disclosure, "first feature" and "second feature" may include one or more of the features.

[0124] In the description of this disclosure, "multiple" means two or more.

[0125] In the description of this disclosure, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0126] In the description of this disclosure, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0127] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0128] Although embodiments of this disclosure have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A rotor assembly for an electric motor, comprising: The rotor body (11) is provided with p magnetic pole pairs, and a first magnetic steel slot group (12) and a second magnetic steel slot group (13) are formed on the rotor body (11) in the radial direction. The first magnet slot group (12) includes a first magnet slot (121) and a second magnet slot (122). In the first magnet slot group (12), the minimum central angle formed between the radial outer end of the first magnet slot (121) and the radial outer end of the second magnet slot (122) and the center of the rotor body (11) is α1, α1=(k1×180°) / p; The second magnet slot group (13) includes a third magnet slot (131) and a fourth magnet slot (132). In the second magnet slot group (13), the minimum central angle formed between the radial outer end of the third magnet slot (131) and the radial outer end of the fourth magnet slot (132) and the center of the rotor body (11) is α2, where α2 = (k2 × 180°) / p; and satisfies: 0.3≤k1≤0.35, 0.55≤k2≤0.

65.

2. The rotor assembly (1) for an electric motor according to claim 1, wherein, In the first magnet slot group (12), a first gap is formed between the first magnet slot (121) and the second magnet slot (122), and the first gap gradually increases in the radially outward direction; A second gap is formed between the third magnet groove (131) and the fourth magnet groove (132) in the second magnet groove group (13), and the second gap gradually increases in the radially outward direction.

3. The rotor assembly (1) for an electric motor according to claim 1 or 2, further comprising: The first magnet (1211) is housed in the first magnet slot (121); The second magnet (1221) is housed within the second magnet slot (122); Wherein, on the cross section of the rotor body (11), the angle between the radial outer edge of the first magnet (1211) and the radial outer edge of the second magnet (1221) is α3, α3=k3×α1, and satisfies: 5≤k3≤6; A third magnet (1311), wherein the third magnet (1311) is housed within the third magnet slot (131); and The fourth magnet (1321), the fourth magnet (1321) and the fourth magnet groove (132); Wherein, on the cross section of the rotor body (11), the angle between the radial outer edge of the third magnet (1311) and the radial outer edge of the fourth magnet (1321) is α4, α4=k4×α2, and satisfies: 2≤k4≤3.

4. The rotor assembly (1) for an electric motor according to claim 2, wherein, The condition k2 satisfies 0.58≤k2≤0.6; the condition k1 satisfies 0.32≤k1≤0.

34.

5. The rotor assembly (1) for an electric motor according to any one of claims 1-4, wherein, The rotor body (11) has a rotor auxiliary groove (15) that opens outward in the radial direction on its radial outer edge.

6. The rotor assembly (1) for an electric motor according to claim 5, wherein, The central angle formed by the two ends of the rotor auxiliary groove (15) in the circumferential direction with the center of the rotor body (11) is β, and satisfies: 1°≤β≤2°.

7. The rotor assembly (1) for an electric motor according to claim 5, wherein, The first magnet slot group (12) and the second magnet slot group (13) are respectively symmetrically arranged about the d-axis. The angle between the straight line passing through the center of the rotor auxiliary slot (15) radially along the rotor body (11) and the d-axis is γ, and satisfies: 0.7×α2≤γ≤0.75×α2.

8. The rotor assembly (1) for an electric motor according to any one of claims 5-7, wherein, The rotor auxiliary groove (15) has a radial depth of L1, and satisfies: 0.3mm≤L1≤1mm.

9. The rotor assembly (1) for an electric motor according to any one of claims 5-8, wherein, The rotor auxiliary groove (15) is constructed as an arc groove.

10. The rotor assembly (1) for an electric motor according to any one of claims 1-9, wherein, The second magnet slot group (13) also includes a plurality of fifth magnet slots (133) located between the third magnet slot (131) and the fourth magnet slot (132); The length of the magnet in the third magnet groove (131) in the extension direction of the third magnet groove (131) and the length of the magnet in the fourth magnet groove (132) in the extension direction of the fourth magnet groove (132) are both L2. The length of the magnet in any one of the plurality of fifth magnet grooves (133) is L3, and satisfies: 1.9≤L2 / L3≤2.

5.

11. The rotor assembly (1) for an electric motor according to claim 10, wherein, A first connecting portion (141) is formed between two adjacent fifth magnet slots (133) of the plurality of fifth magnet slots (133).

12. The rotor assembly (1) for an electric motor according to claim 11, wherein, The rotor body (11) has a second connecting portion (142) formed between the third magnet slot (131) and the fifth magnet slot (133) of the plurality of fifth magnet slots (133) adjacent to the third magnet slot (131), and the rotor body (11) has a third connecting portion (143) formed between the fourth magnet slot (132) and the fifth magnet slot (133) of the plurality of fifth magnet slots (133) adjacent to the fourth magnet slot (132).

13. An electric motor (20) comprising a rotor assembly (1) according to any one of claims 1-12.

14. The motor (20) according to claim 13, further comprising: The stator (21) is disposed on the outer periphery of the rotor assembly (1). An air gap (23) is formed between the stator (21) and the rotor body (11). The air gap (23) is d1 in the radial direction and satisfies: 1.5mm≤d1≤3mm.

15. The motor (20) according to claim 14, wherein, The stator (21) is provided with a plurality of stator slots (212) arranged at intervals in the circumferential direction, and each stator slot (212) is provided with a flat wire winding (24).

16. The motor (20) according to claim 15, wherein, The flat wire windings (24) in each stator slot (212) are constructed to be at least 10 layers.

17. The motor (20) according to claim 14, wherein, The stator (21) has a plurality of teeth (211) arranged at intervals in the circumferential direction on its inner periphery. A stator groove (212) is formed between two adjacent teeth (211) among the plurality of teeth (211). At least one of the teeth (211) has a stator auxiliary groove (213) that is recessed in the radial direction on the tooth tip facing the air gap (23).

18. The motor (20) according to claim 17, wherein, The width of the stator auxiliary groove (213) is d2, and the tooth tip width of the tooth (211) is d3, and satisfies: 1 / 3≤d2 / d3≤1 / 2.

19. The motor (20) according to claim 17 or 18, wherein, The stator auxiliary groove (213) has a radial depth of d4, and satisfies: 0.1mm≤d4≤0.3mm.

20. The motor (20) according to any one of claims 17-19, wherein, The rotor body (11) has N magnetic poles arranged circumferentially, and satisfies: 2≤N≤8, where N is an even number; the stator (21) has N×M stator slots, and satisfies: M=3x, where x is a positive integer.

21. A vehicle (30) comprising an electric motor (20) according to any one of claims 13-20.

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