Electric motor, electric assembly, and vehicle

Abstract

An electric motor, an electric assembly, and a vehicle. The electric motor comprises a rotor and a stator. The rotor is rotatably arranged on the inner periphery of the stator, and an air gap is formed between the stator and the rotor. The width of the air gap is d1, and satisfies: 1.5mm≤d1≤3mm.

Description

Electric motors, electric powertrains and vehicles

[0001] This application claims priority to Chinese patent application No. 202410526839.2, 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 electric motor technology, and more particularly to an electric motor, an electric powertrain, and a vehicle. Background Technology

[0003] An electric motor is a device that converts electrical energy into mechanical energy, and it has a wide range of applications in various fields. In the transportation sector, electric motors are used in vehicles such as automobiles, electric cars, and high-speed trains, providing convenience for people's travel. Summary of the Invention

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

[0005] On one hand, an electric motor is provided. According to the electric motor of this disclosure, the width of the air gap between the rotor and stator is set within the range of 1.5 mm to 3 mm, effectively suppressing power attenuation in the high-speed region of the motor and improving the output power of the motor in the high-speed region, thus meeting the drive requirements. Furthermore, the electric motor of this disclosure eliminates the traditional method of improving noise, vibration, and harshness (NVH) performance by skewing the poles, and reduces windage losses by reducing eddy current losses caused by harmonic magnetic fields to the stator and rotor, thereby improving the efficiency of the motor.

[0006] On the other hand, an electric powertrain including the aforementioned motor is provided.

[0007] On the other hand, a vehicle including the aforementioned electric powertrain is provided.

[0008] The motor according to this disclosure includes a rotor and a stator, the rotor being rotatably disposed on the inner periphery of the stator, an air gap being formed between the stator and the rotor, the air gap being d1 in the radial direction and satisfying: 1.5mm≤d1≤3mm.

[0009] The width of the air gap affects the power attenuation of the motor in the high-speed range. Within a certain range, a larger air gap results in less power attenuation; however, an increased air gap width also affects the utilization rate of the permanent magnet. Therefore, the air gap width needs to be maintained within a suitable range. Experiments and analysis show that when the air gap width is less than 1.5mm, the power attenuation is significant. Increasing the width of air gap 13 in this case will increase the magnetic reluctance at that location. Conversely, when the air gap width is greater than 3mm, the magnetic reluctance is too high, resulting in low utilization of the permanent magnet. Therefore, maintaining the air gap width within the range of 1.5mm to 3mm can effectively suppress power attenuation in the high-speed range while ensuring the utilization rate of the permanent magnet.

[0010] When a motor operates at high speed, the stator and rotor cores generate significant eddy current losses due to the magnetic field. These losses increase with speed and frequency. Increasing the air gap width significantly reduces harmonic content in the air gap magnetic field, lowering eddy current losses at high speeds and improving the motor's rated power and efficiency. Therefore, increasing the air gap width suppresses magnetic field harmonics. When the air gap width is between 1.5mm and 3mm, the large air gap effectively suppresses harmonics, resulting in lower torque fluctuations, torque amplitudes at various orders, and radial electromagnetic forces under maximum load. Even with direct-pole configuration, the motor maintains good NVH performance. Compared to traditional skewed-pole configurations for NVH improvement, this not only simplifies rotor manufacturing but also reduces windage losses during rotor rotation, further enhancing motor efficiency.

[0011] 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.

[0012] According to some embodiments of this disclosure, the flat wire winding in each of the stator slots is configured as at least 10 layers.

[0013] 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, and the stator slot is formed between two adjacent teeth in the plurality of teeth. At least one of the teeth in the plurality of teeth has a stator auxiliary groove recessed in the radial direction on the tooth tip facing the air gap side.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] According to some embodiments of this disclosure, the rotor is provided with magnets, and the ratio between the area occupied by the magnets and the area of ​​the rotor on the cross section of the rotor is a, and satisfies: 0.2≤a≤0.25.

[0018] According to some embodiments of this disclosure, the motor further includes a rotor with p magnetic pole pairs. The rotor has a first magnetic slot group and a second magnetic slot group arranged radially in sequence. The first magnetic slot group 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 is α1, where α1 = (k1 × 180°) / p. The second magnetic slot group 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 is α2, where α2 = (k2 × 180°) / p. Furthermore, k1 and k2 satisfy the following conditions: 0.3 ≤ k1 ≤ 0.35, 0.55 ≤ k2 ≤ 0.65.

[0019] 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.

[0020] According to some embodiments of this disclosure, the motor further includes a first magnet and a second magnet, which are respectively housed within slots higher than the first magnet slot and the second magnet slot. In the cross-section of the rotor, 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 motor further includes a third magnet and a fourth magnet, which are respectively housed within slots of the third magnet and the fourth magnet slot. In the cross-section of the rotor, 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.

[0021] According to some embodiments of this disclosure, k2 satisfies 0.58 ≤ k2 ≤ 0.6. k1 satisfies 0.32 ≤ k1 ≤ 0.34.

[0022] According to some embodiments of this disclosure, the rotor has a rotor auxiliary groove formed on its radially outer edge, which opens outward in the radial direction. The central angle formed by the two ends of the rotor auxiliary groove and the center of the rotor in the circumferential direction is β, and satisfies: 1°≤β≤2°.

[0023] According to some embodiments of this disclosure, the first magnet slot group and the second magnet slot group are symmetrically arranged about the d-axis, and the angle between the straight line passing through the center of the rotor auxiliary slot along the radial direction of the rotor and the d-axis is γ, and satisfies: 0.7×α2≤γ≤0.75×α2.

[0024] According to some embodiments of this disclosure, the second magnet slot group further includes a plurality of fifth magnet slots, which are respectively located between the third magnet slot and the bottom fourth magnet slot. The length of the magnet in the third magnet slot in the extension direction of the third magnet slot and the length of the magnet in the fourth magnet slot in the extension direction of the fourth magnet slot are both L2, and the length of the magnet in the fifth magnet slot is L3, satisfying: 1.9≤L2 / L3≤2.5.

[0025] 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.

[0026] According to some embodiments of this disclosure, the rotor forms a second connecting portion between the third magnet slot and the fifth magnet slot connected to the third magnet slot among the plurality of fifth magnet slots, and forms a third connecting portion between the fourth magnet slot and the fifth magnet slot adjacent to the fourth magnet slot among the plurality of fifth magnet slots.

[0027] According to some embodiments of this disclosure, the rotor is formed with multiple sets of weight-reducing holes, which are disposed on the radial outer side of the first magnet slot group, and any one set of weight-reducing holes includes at least one weight-reducing hole.

[0028] The electric powertrain according to this disclosure is briefly described below.

[0029] The electric powertrain disclosed herein includes the motor described in the above embodiments. Since the electric powertrain of this disclosure is equipped with the motor described in the above embodiments, the efficiency and NVH performance of the electric powertrain can be improved after the motor is installed within the electric powertrain.

[0030] The vehicle according to this disclosure is briefly described below.

[0031] The vehicle disclosed herein includes the electric powertrain described in the above embodiments. Because the vehicle of this disclosure is equipped with the electric powertrain described in the above embodiments, the vehicle exhibits higher NVH performance, stronger power, and greater reliability after the electric powertrain is installed.

[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 complete structural diagram of the stator and rotor according to some embodiments;

[0035] Figure 2 is a magnified view of a portion of circle A in Figure 1;

[0036] Figure 3 is a graph showing the relationship between the air gap width and the motor power attenuation value according to some embodiments;

[0037] Figure 4 is a structural diagram of a rotor corresponding to one magnetic pole according to some embodiments;

[0038] Figure 5 is a structural diagram of a stator and rotor of a magnetic pole according to some embodiments;

[0039] Figure 6 shows the relationship between the number of layers in the flat wire winding and eddy current loss.

[0040] Figure 7 shows the relationship between the number of layers in a flat wire winding and its efficiency.

[0041] Figure 8 shows the change of torque over time with and without the stator auxiliary slots open.

[0042] Figure 9 shows the radial pressure variation of the stator at different orders when the stator auxiliary slot is open and when the stator auxiliary slot is not open.

[0043] Figure 10 shows the changes in average torque and torque pulsation rate for different values ​​of d2 / d3;

[0044] Figure 11 shows the relationship between the air gap width and the area ratio of the magnet.

[0045] Figure 12 is a structural diagram of a rotor according to some embodiments;

[0046] Figure 13 is a structural diagram of one magnetic pole in a rotor according to some embodiments;

[0047] Figure 14 shows the relationship between torque pulsation rate and K1 and K2;

[0048] Figure 15 is another structural diagram of a magnetic pole in a rotor according to some embodiments;

[0049] Figure 16 shows the relationship between torque pulsation rate and K3 and K4;

[0050] Figure 17 shows the relationship between torque pulsation rate and β;

[0051] Figure 18 is another structural diagram of a magnetic pole in a rotor according to some embodiments;

[0052] Figure 19 shows the relationship between torque pulsation rate and γ / α2;

[0053] Figure 20 shows the relationship between the stress on the second connection (third connection) and L2 / L3;

[0054] Figure 21 is a block diagram of an electric powertrain according to some embodiments; and

[0055] Figure 22 is a block diagram of a vehicle according to some embodiments.

[0056] Reference numerals: Vehicle 1000; Electric assembly 100; Motor 1; Stator 11, Gear 111, Stator slot 112, Stator auxiliary slot 113; Rotor 12; First magnet slot group 120, First magnet slot 121, First magnet 1211, Second magnet slot 122, Second magnet 1221, Weight reduction hole 123; First interval 201; Second magnet slot group 130, Third magnet slot 131, Third magnet 1311, Fourth magnet slot 132, Fourth magnet 1321, Fifth magnet slot 133; Second interval 202; First connecting part 141, Second connecting part 142, Third connecting part 143; Air gap 13, Flat wire winding 14, Rotor auxiliary slot 15. Detailed Implementation

[0057] 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.

[0058] In related technologies, when a motor is running, according to its performance curve, the motor's power decreases as the speed increases, failing to meet drive requirements. Furthermore, the structure of the stator and rotor of a permanent magnet motor affects its performance. Common motors have fewer reinforcing structures on the rotor, requiring thicker magnetic bridges at high speeds, which leads to severe magnetic leakage. Simultaneously, the number of winding layers on the stator also affects eddy current losses. In addition, the air gap between the rotor and stator in common motors is typically small. While this reduces magnetic reluctance between the stator and rotor, a small air gap makes it difficult to suppress magnetic field harmonics and power attenuation in high-speed regions.

[0059] The following describes some embodiments of motors according to the present disclosure with reference to the accompanying drawings.

[0060] In some embodiments of this disclosure, as shown in Figures 1 and 2, the motor 1 includes a rotor 12 and a stator 11, with the rotor 12 rotatably disposed on the inner circumference of the stator 11. An air gap 13 is formed between the stator 11 and the rotor 12, with the air gap 13 having a radial distance d1, satisfying: 1.5mm ≤ d1 ≤ 3mm.

[0061] According to some embodiments of this disclosure, the motor 1 defines an air gap 13 between the stator 11 and the rotor 12. The radial distance of the air gap 13 is d1, and satisfies: 1.5mm ≤ d1 ≤ 3mm. In the industry, the length of the air gap 13 in permanent magnet synchronous motors 1 is generally less than 1.5mm. Compared to related technologies with smaller air gap 13 widths, the motor 1 in some embodiments of this disclosure increases the width of the air gap 13, thereby helping to suppress power attenuation and magnetic field harmonics in the high-speed region of the motor 1, and improving the efficiency and NVH performance of the motor 1.

[0062] It should be noted that, with the magnetic flux density of the air gap 13 remaining constant, a larger air gap 13 results in greater magnetic reluctance between the stator 11 and rotor 12, and a smaller inductance in the motor 1. This leads to an increase in the field weakening current in the high-speed constant-power region of the motor 1, and consequently, an increase in the output power in the high-speed region. Therefore, a larger air gap 13 helps suppress power attenuation in the high-speed region. The constant magnetic flux density of the air gap 13 can be understood as increasing the amount of permanent magnets to ensure that the magnetic flux density of the air gap 13 is the same as that in related technologies, thereby avoiding the negative impacts of changes in magnetic flux density.

[0063] As shown in Figure 11, to maintain a constant magnetic flux density in the air gap 13, the area ratio of the magnets in the rotor 12 needs to increase with the width of the air gap 13. This can also be understood as follows: when the width of the air gap 13 increases, to maintain a constant magnetic flux density in the air gap 13 and ensure high power density in the motor 1, the amount of magnets required needs to be increased. When the width of the air gap 13 is greater than 3mm, the required amount of magnets is excessive, which is detrimental to the lightweight design of the motor 1.

[0064] The width of the air gap 13 affects the power attenuation of motor 1 in the high-speed region. Within a certain range, a larger air gap 13 results in smaller power attenuation; however, increasing the width of the air gap 13 also affects the utilization rate of the permanent magnet. Therefore, the width of the air gap 13 needs to be kept within a suitable range. As shown in Figure 3, the width of the air gap 13 and the power attenuation value are approximately linearly related within a certain range. When the width of the air gap 13 is less than 1.5 mm, the power attenuation is relatively large. As the width of the air gap 13 increases, the magnetic reluctance at the air gap 13 position also increases. When the width of the air gap 13 is greater than 3 mm, it leads to excessive magnetic reluctance, resulting in low utilization of the permanent magnet. Therefore, by keeping the width of the air gap 13 within the range of 1.5 mm to 3 mm, the power attenuation in the high-speed region can be effectively suppressed while ensuring the utilization rate of the permanent magnet.

[0065] When motor 1 operates in the high-speed range, a large amount of eddy current loss is generated in the stator core 11 and rotor core 12 due to the magnetic field. The higher the rotational speed and frequency of motor 1, the greater the eddy current loss in rotor 12. When the width of air gap 13 increases, the harmonic content in the magnetic field of air gap 13 decreases significantly, reducing eddy current loss during high-speed rotor 12 operation. This improves the rated power and efficiency of motor 1 in the high-speed range. Therefore, increasing the width of air gap 13 can suppress magnetic field harmonics. When the width of air gap 13 is between 1.5mm and 3mm, because a large air gap 13 can suppress magnetic field harmonics, the torque fluctuation, torque amplitude at various orders, and radial electromagnetic force of motor 1 under maximum load are all at a relatively low level. In this case, motor 1 can still maintain good NVH performance even under direct polarity conditions. Compared to the traditional solution of using a skewed pole configuration to improve NVH performance, the motors in some embodiments of this disclosure not only improve the ease of manufacturing the rotor 12, but also reduce the wind friction loss experienced by the rotor 12 during rotation, thereby further improving the efficiency of the motor 1.

[0066] According to some embodiments of this disclosure, as shown in Figures 1 and 2, a plurality of stator slots 112 are provided on the stator 11 at intervals in the circumferential direction, and flat wire windings 14 are disposed in the plurality of stator slots 112. For example, the stator 11 is provided with a plurality of stator slots 112 for assembling windings, and the plurality of stator slots 112 are arranged at intervals in the circumferential direction of the stator 11, and flat wire windings 14 can be disposed in each stator slot 112. Compared with conventional round wire windings, the gap between the flat wire windings 14 and the stator slots 112 is smaller after the flat wire windings 14 are assembled in the stator slots 112. Therefore, assembling flat wire windings 14 in the stator slots 112 can improve the slot fill factor of the stator slots 112, thereby effectively improving the power density and efficiency of the motor 1.

[0067] According to some embodiments of this disclosure, the flat wire winding 14 in each stator slot 112 is constructed with at least 10 layers. Compared to the related art scheme using 4 layers of flat wire winding 14, the motor 1 in some embodiments of this disclosure increases the number of layers of flat wire winding 14 by assembling at least 10 layers of flat wire winding 14 in each stator slot 112. This can effectively reduce the eddy current losses in the windings caused by the skin effect when the motor 1 is running in the high-speed range, thereby improving the efficiency and rated power of the motor 1 in the high-speed range. In addition, combined with embodiments that maintain the width of the air gap 13 at 1.5mm to 3mm, some embodiments of this disclosure can comprehensively improve the efficiency and rated power of the motor 1 in the high-speed range to further meet the drive requirements.

[0068] As can be seen from Figures 6 and 7, increasing the number of layers of the flat wire winding 14 significantly reduces eddy current losses and slightly improves efficiency. Therefore, under the same high-speed operating conditions, the motor 1 with 10 layers of flat wire winding 14 has lower losses than the motor 1 with 4 layers of flat wire winding in related technologies. Under the same heat dissipation conditions, the rated power of the motor 1 with 10 layers of flat wire winding 14 will also be higher.

[0069] In related technologies, as the speed of motor 1 increases, the noise of motor 1 increases, affecting the NVH performance of motor 1.

[0070] According to some embodiments of the present disclosure, the inner circumference of the stator 11 is provided with a plurality of teeth 111 arranged at intervals in the circumferential direction, and a stator groove 112 is formed between two adjacent teeth 111. At least one of the teeth 111 has a stator auxiliary groove 113 recessed in the radial direction on the tooth tip facing the air gap 13.

[0071] As shown in Figures 4 and 5, the stator 11 is also provided with a plurality of teeth 111 arranged at intervals on its inner circumference. A stator slot 112 is formed between two adjacent teeth 111. The tooth tip of any one of the plurality of teeth 111 protrudes towards the stator slot 112 on both sides in the circumferential direction. This can improve the assembly stability of the flat wire winding 14. At least one of the plurality of teeth 111 has a stator auxiliary slot 113 that is recessed in the radial direction at the tooth tip position. The stator auxiliary slot 113 can effectively reduce the magnetic field harmonics of the air gap 13, thereby reducing the torque pulsation and electromagnetic radial force of the motor 1 and improving the NVH performance of the motor 1.

[0072] As shown in Figure 8, 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 11 has no stator auxiliary slot 113, while the solid line represents the torque value over time after the stator 11 has the stator auxiliary slot 113. It is clear from Figure 8 that when the stator auxiliary slot 113 is installed on the stator 11, the torque fluctuation is significantly reduced, meaning the torque pulsation is reduced. This effectively suppresses the tangential electromagnetic force, thereby effectively improving the NVH performance of the motor 1.

[0073] As shown in Figure 9, the radial pressure of the stator 11 is compared under different orders when the stator auxiliary groove 113 is opened and when the stator auxiliary groove 113 is not opened. As can be seen from Figure 9, when the stator auxiliary groove 113 is opened on the stator 11, the radial pressure of the stator 11 under various orders can be effectively reduced.

[0074] In some embodiments, the number of stator auxiliary slots 113 can be determined based on parameters such as the actual number of teeth 111 and the number of stator slots 112. For example, in a 6-pole, 72-slot stator 11, the 6-pole, 72-slot designation means that the stator has 6 magnetic poles and 72 stator slots 112, that is, each magnetic pole has 12 stator slots 112 and 12 teeth 111. Since the motor 1 uses a three-phase winding, each phase of the stator 11 has 4 stator slots 112 and 4 teeth 111. In this case, stator auxiliary slots 113 can be provided at the tooth tip positions of two of the four teeth 111, i.e., two stator auxiliary slots 113 are machined. In this way, the harmonics of the magnetic field in the air gap 13 can be effectively reduced without affecting the structure and other performance characteristics of the motor 1. The arrangement of stator auxiliary slots 113 can be determined based on the actual number of teeth 111 in each phase.

[0075] According to some embodiments of this disclosure, as shown in FIG2, the width of the stator auxiliary groove 113 is d2, and the tooth tip width of the tooth portion 111 is d3, satisfying: 1 / 3≤d2 / d3≤1 / 2. That is, during the machining of the stator auxiliary groove 113, the relationship between the groove width d2 of the stator auxiliary groove 113 and the tooth tip width d3 of the tooth portion 111 needs to satisfy: 1 / 3≤d2 / d3≤1 / 2, where the groove width can be understood as the width of the stator auxiliary groove 113.

[0076] Understandably, the stator auxiliary slot 113 effectively reduces magnetic field harmonics and improves the NVH performance of motor 1. If d2 / d3 < 1 / 3, meaning the slot width of the stator auxiliary slot 113 is too small, its ability to reduce magnetic field harmonics will be weakened. If d2 / d3 > 1 / 2, meaning the slot width of the stator auxiliary slot 113 is too large, it will affect the mechanical structural strength of stator 11. Therefore, limiting d2 / d3 to the range of 1 / 3 to 1 / 2 allows stator 11 to effectively reduce magnetic field harmonics while ensuring mechanical structural strength, thereby improving the efficiency and NVH performance of motor 1.

[0077] As shown in Figure 10, the solid line represents the torque ripple rate variation with different values ​​of d2 / d3, and the dashed line represents the average torque variation with different values ​​of d2 / d3. It is clear from Figure 10 that when d2 / d3 is between 1 / 3 and 1 / 2, the average torque decreases only slightly, and the torque fluctuation rate is low. Therefore, keeping d2 / d3 within the range of 1 / 3 to 1 / 2 can improve the NVH performance of motor 1.

[0078] According to some embodiments of this disclosure, as shown in FIG2, the stator auxiliary groove 113 has a radial depth of d4, which satisfies: 0.1mm≤d4≤0.3mm. That is, when the stator auxiliary groove 113 is processed, the depth d4 of the stator auxiliary groove 113 must satisfy: 0.1mm≤d4≤0.3mm. Here, the depth can be understood as the radial depth of the stator auxiliary groove 113.

[0079] Understandably, a suitable depth of the stator auxiliary slot 113 helps improve the electromagnetic performance of the motor 1. When d4 < 0.1 mm, meaning the depth of the stator auxiliary slot 113 is too shallow, it may not achieve the desired effect, resulting in a weakened ability of the stator auxiliary slot 113 to reduce magnetic field harmonics. Conversely, when d4 > 0.3 mm, meaning the depth of the stator auxiliary slot 113 is too deep, it will affect the mechanical structural strength of the stator 11. By setting the slot depth of the stator auxiliary slot 113 within the range of 0.1 mm to 0.3 mm, the magnetic field distribution can be effectively adjusted, improving the efficiency and power density of the motor 1. While ensuring the structural strength of the stator 11, it can also reduce magnetic field harmonics and improve the NVH performance of the motor 1.

[0080] Furthermore, the arrangement of the stator auxiliary slot 113 is also related to the heat dissipation of the motor 1. When the stator auxiliary slot 113 satisfies 1 / 3≤d2 / d3≤1 / 2 and 0.1mm≤d4≤0.3mm, it can increase the heat dissipation area, improve the heat dissipation performance of the motor 1, and help reduce the heat generated by the motor 1 during operation, thereby improving the thermal stability of the motor 1. The depth range of 0.1mm to 0.3mm makes the machining process of the stator auxiliary slot 113 relatively easy to control, and also helps to ensure machining accuracy and consistency.

[0081] According to one embodiment of this disclosure, the rotor 12 has N magnetic poles spaced circumferentially, satisfying: 2≤N≤8, where N is an even number. The stator 11 has N×M stator slots 112, satisfying: M=3x, where x is a positive integer. In some embodiments of this disclosure, the rotor 12 has N magnetic poles, where N can be any one of 2, 4, 6, or 8. Correspondingly, the number of stator slots 112 is N×M, i.e., 2M, 4M, 6M, or 8M. Furthermore, since the motor 1 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 rotor 12 and stator 11 configuration schemes in some embodiments of this disclosure, such as the air gap 13 width and the number of flat wire winding layers 14, can be used for motors 1 of different specifications, and have a wide range of applications.

[0082] According to some embodiments of this disclosure, the rotor 12 is provided with magnets. The ratio of the area occupied by the magnets to the area of ​​the rotor 12 in its cross-section is 'a', and satisfies: 0.2 ≤ a ≤ 0.25. This can be understood as the area occupied by the magnets on the rotor 12 being 0.2 to 0.25 times the area of ​​the rotor 12.

[0083] It should be noted that when a < 0.2, the amount of magnets used is too small, resulting in insufficient magnetic flux and magnetic field strength on rotor 12, leading to low output power of motor 1. When a > 0.25, the amount of magnets used is too large, making rotor 12 too heavy and resulting in poor dynamic performance. Therefore, setting a between 0.2 and 0.25 allows for achieving high energy conversion efficiency in rotor 12 while maintaining good dynamic performance.

[0084] According to some embodiments of this disclosure, the rotor 12 is provided with p magnetic pole pairs. A first magnetic slot group 120 and a second magnetic slot group 130 are formed on the rotor 12 in a radially arranged sequence. The first magnetic slot group 120 includes a first magnetic slot 121 and a second magnetic slot 122. As shown in FIG12, in the first magnetic slot group 120, 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 12 is α1, α1 = (k1 × 180°) / p. The second magnetic slot group 130 includes a third magnetic slot 131 and a fourth magnetic slot 132. In the second magnetic slot group 130, 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 12 is α2, α2 = (k2 × 180°) / p. The values ​​of k1 and k2 satisfy: 0.3≤k1≤0.35, 0.55≤k2≤0.65.

[0085] According to some embodiments of this disclosure, a first magnet slot group 120 and a second magnet slot group 130 arranged radially are machined on the rotor 12 of the motor 1. Each magnet slot group contains different magnet slots, and the number of different magnet slots is not limited. The specific distribution can be determined according to the actual magnetic flux requirements. For example, the first magnet slot group 120 can contain a first magnet slot 121 and a second magnet slot 122, and the second magnet slot group 130 can contain a third magnet slot 131 and a fourth magnet slot 132. Each magnet slot can accommodate a corresponding magnet.

[0086] As shown in Figures 12 and 13, the rotor 12 has P pole pairs, where each pole pair can be understood as having two poles. For any given pole, the positions of the magnet slots can be rationally planned to optimize the electromagnetic performance of the motor 1. For example, in the first magnet slot group 120, the smallest central angle formed between the radial outer ends of the first magnet slot 121 and the second magnet slot 122 and the center of the rotor 12 is the first pole arc angle, which can be represented by α1, and α1 satisfies: α1=(k1×180°) / p, where 0.3≤k1≤0.35. For example, if P=3, i.e., the rotor 12 has 3 pole pairs, then α1=k1×60°, i.e., 18°≤α1≤21°, where k1=0.33, and in this case, α1=19.8°. Similarly, in the second magnet slot group 130, 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 12 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 12 has 3 pole pairs, then α2=k2×60°, that is, 33°≤α1≤39°, where k1=0.59, and at this time, α1=35.4°.

[0087] 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 motor 1 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 motor 1 can be balanced, thereby achieving higher efficiency, greater output power, and better dynamic performance of motor 1. Appropriate α1 and α2 can also effectively reduce magnetic field harmonics, thereby reducing the vibration and noise of motor 1 and improving its NVH performance. Furthermore, fixing the values ​​of α1 and α2 in the production of motor 1 simplifies the production process and manufacturing flow, reduces manufacturing costs, and also helps to ensure product consistency and reliability.

[0088] As shown in Figure 14, 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 less than 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, improves the NVH performance of motor 1, and thus reduces the vibration and noise of motor 1.

[0089] According to some embodiments of this disclosure, referring to FIG13, a first interval 201 is formed between the first magnet slot 121 and the second magnet slot 122 in the first magnet slot group 120, 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 130, 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 12. 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 12. 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 1.

[0090] According to some embodiments of this disclosure, as shown in Figures 13 and 15, the motor 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 in the first magnet slot 121 and the second magnet slot 122. In the cross-section of the rotor 12, 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 in the third magnet slot 131 and the fourth magnet slot 132. In the cross-section of the rotor 12, 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.

[0091] 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 1.

[0092] 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.

[0093] When rotor 12 operates at high speed, the centrifugal force on the area covered by the magnet slots in each magnetic pole of rotor 12 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 will be. At this time, the area covered by the magnet slot group will also be larger, which will lead 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 rotor 12. 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.

[0094] In any magnetic pole, as shown in Figure 15, in the first magnetic steel slot group 120, the magnetic steel angle formed between the radially outer edge of the first magnet 1211 and the radially outer edge of the second magnet 1221 is α3, and satisfies α3=k3×α1. Here, the radially outer edge can be understood as follows: both the first magnet 1211 and the second magnet 1221 are rectangular, and their edges closest to each other are the radially outer edges, 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 steel slot group 120, the magnetic steel 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 120 is too large, it will increase the area occupied by the first magnet slot group 120 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.

[0095] 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 magnet slot group 130 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°. It should be noted that α4 can be a value of α2 multiplied by k4, meaning that in the second magnet slot group 130, 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 130 is too large, it will increase the area occupied by the second magnet slot group 130 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.

[0096] Furthermore, as shown in Figure 16, the relationship between torque ripple rate and k3 and k4 is illustrated. It is evident from the figure 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, improves the NVH performance of motor 1, and thus reduces the vibration and noise of motor 1.

[0097] In summary, the α3 and α4 design schemes allow for the rational planning of the first magnet slot group 120 and the second magnet slot group 130 in each magnetic pole, enabling more precise adjustment of the magnetic field distribution of motor 1. This design helps reduce harmonics in the magnetic field, improves the sinusoidal nature of the magnetic field, and thus improves the NVH performance of motor 1. Furthermore, the optimized magnetic field distribution also helps improve the torque density and efficiency of motor 1, thereby enhancing its overall performance. Moreover, this design considers the different characteristics of the first magnet slot group 120 and the second magnet slot group 130, setting different value ranges for k3 and k4 respectively. This differentiated design can better adapt to changes in the internal magnetic field of motor 1, making the magnetic field more uniform and stable in the radial direction.

[0098] According to some embodiments of this disclosure, k2 satisfies 0.58≤k2≤0.6, and k1 satisfies 0.32≤k1≤0.34. Unlike the ranges of 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 motor 1.

[0099] According to some embodiments of this disclosure, as shown in Figures 12 and 13, a rotor auxiliary slot 15 is formed on the radially outer edge of the rotor 12, opening radially outward. The rotor auxiliary slot 15 can effectively reduce magnetic field harmonics, which helps to improve the NVH performance of the motor 1. In addition, the rotor auxiliary slot 15 can also increase the heat dissipation area, improve the heat dissipation efficiency of the motor 1, and ensure that the motor 1 can operate stably in harsh environments such as high load and high temperature.

[0100] 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 12 is β, and satisfies: 1°≤β≤2°. It is understood that the range of β is small, meaning the rotor auxiliary slot 15 requires high precision. By setting a high-precision rotor auxiliary slot 15, the performance of the motor 1 can be fine-tuned, further optimizing the electromagnetic performance of the motor 1, such as reducing electromagnetic noise and vibration, thereby improving the overall efficiency and performance of the motor 1. Furthermore, a small-sized rotor auxiliary slot 15 ensures the structural strength of the rotor 12, preventing the rotor auxiliary slot 15 from being too large and reducing the strength of the rotor 12, which could lead to damage to the rotor 12 during high-speed operation.

[0101] As shown in Figure 17, the relationship between torque ripple rate and β is illustrated. It is clear from Figure 17 that when 1°≤β≤2°, the torque ripple rate is less than 2%. This helps suppress the harmonic content of the magnetic field, improves the NVH performance of motor 1, and thus reduces the vibration and noise of motor 1.

[0102] According to some embodiments of this disclosure, the first magnet slot group 120 and the second magnet slot group 130 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 12 and the d-axis is γ, and satisfies: 0.7×α2≤γ≤0.75×α2.

[0103] As shown in Figures 15 and 18, the label 'd' in Figure 18 represents the d-axis. It's important to note 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 18 are only for convenient labeling and do not represent the actual structure. The first magnet slot group 120 and the second magnet slot group 130 are symmetrical about the d-axis. This not only improves the overall aesthetics of the rotor 12 but also ensures a uniform structural distribution on the rotor 12, avoiding excessively high or low local strength.

[0104] 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 12 for any magnetic pole of the rotor 12. Compared to a single rotor auxiliary slot 15, the design of two rotor auxiliary slots 15 improves heat dissipation 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 1. This symmetry helps reduce unbalanced components in the magnetic field, lowers vibration and noise of the motor 1, and improves the smoothness of motor operation.

[0105] Secondly, as shown in Figure 18, by precisely controlling the angle γ between the center of the rotor auxiliary slot 15 and the d-axis, and keeping γ 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 regulating effect of the rotor auxiliary slot 15 on the magnetic field of the motor 1 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 bridges 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 1, 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 1.

[0106] Furthermore, as shown in Figure 19, the relationship between torque ripple rate and γ / α2 is illustrated. It is evident from Figure 19 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 motor 1, and thus reduces the vibration and noise of motor 1.

[0107] In some embodiments, the radial depth of the rotor auxiliary groove 15 is L1 and satisfies: 0.3mm ≤ L1 ≤ 1mm. As shown in Figure 18, 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 12. 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 12, and can ensure the reliability and durability of the motor 1. 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 1 while optimizing the electromagnetic performance of the motor 1.

[0108] In some embodiments, the rotor auxiliary slot 15 is configured as an arc-shaped slot. Compared to rotor auxiliary slots 15 of other shapes, 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 1. Furthermore, the arc-shaped rotor auxiliary slot 15 can give the rotor 12 better mechanical properties, enabling the rotor 12 to withstand higher stresses and impacts, which helps to enhance the structural strength of the motor 1 and improve its reliability and durability. In addition, the arc-shaped slot has a relatively simple shape and is easy to manufacture through processes such as machining or casting, reducing the manufacturing cost of the motor 1 and improving production efficiency.

[0109] According to one embodiment of this disclosure, the second magnet slot group 130 further includes a fifth magnet slot 133 located between the third magnet slot 131 and the fourth magnet slot 132, and the second magnet slot group 130 includes a plurality of fifth magnet slots 133. 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 length of the magnet in the fifth magnet slot 133 is L3, and satisfying: 1.9≤L2 / L3≤2.5.

[0110] 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.

[0111] In some embodiments, a fifth magnet may be disposed within the fifth magnet slot 133. 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, L2 is too large and L3 is too small, which will increase 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, thereby increasing the stress in the area where the magnet slot group is located and affecting the reliability of the rotor at high speed. When L2 / L3 < 1.9, L2 is too large and L3 is too small, which will lead to uneven distribution of mechanical strength of the rotor 12 structure. Moreover, an excessively large L2 may cause local magnetic circuit saturation, making it impossible for magnetic flux to effectively pass through the magnet and the air gap, thereby reducing the magnetic energy utilization rate of the motor 1.

[0112] The range of L2 / L3 values ​​can also be referenced in Figure 20, which shows the stress distribution of the reinforcing structure between the third magnet slot 131 or the fourth magnet slot 132 and the fifth magnet slot 133 when the rotor rotates at 30,000 rpm. As shown in Figure 20, it is easy to see the pattern of the curves in Figure 20. 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 the third magnet slot 131 or the fourth magnet slot 132 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 the third magnet slot 131 or the fourth magnet slot 132 and the fifth magnet slot 133 is very likely to exceed 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, can the thickness of the reinforcing structure between the third magnet slot 131 or the fourth magnet slot 132 and the fifth magnet slot 133 be appropriately reduced when motor 1 reaches the same limiting speed. This ensures stable operation of motor 1 at ultra-high speeds while effectively reducing leakage flux and increasing the main magnetic flux content, thereby improving the power density and torque density of motor 1.

[0113] Therefore, setting L2 / L3 in the range of 1.9 to 2.5 helps to improve the output torque and power density of motor 1, meeting the performance requirements of various application scenarios.

[0114] 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 120. The arrangement of magnets in the sixth magnet slot can refer to the above embodiments or be determined according to actual needs.

[0115] According to one embodiment of the present disclosure, as shown in FIG18, a first connecting portion 141 is formed between two adjacent fifth magnet slots 133 in a plurality of fifth magnet slots 133.

[0116] In actual processing, a first connecting part 141 can be set between adjacent fifth magnet slots 133. The setting of the first connecting part 141 can increase the number of reinforcing structures on the rotor, which can improve the structural strength of the rotor 12. When the motor 1 reaches the same speed, the thickness of the magnetic isolation bridge can be appropriately reduced to reduce magnetic leakage.

[0117] According to one embodiment of this disclosure, a second connecting portion 142 is formed between the fifth magnet slot 133 adjacent to the third magnet slot 131 in the third magnet slot 131 and among the plurality of fifth magnet slots 133, and a third connecting portion 143 is formed between the fifth magnet slot 133 adjacent to the fourth magnet slot in the fourth magnet slot 132 and among the plurality of fifth magnet slots 133. The third magnet slot 131, the fourth magnet slot 132, and the fifth magnet slot 133 cooperate with each other to form a U-shaped structure. Compared with the "V"-shaped or "I"-shaped magnet slot structure 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 12, improves the overall strength of the rotor 12, and allows the thickness of the magnetic isolation bridge to be thinner than in conventional solutions at the limit speed, thereby reducing the leakage flux at the magnetic isolation bridge location, further reducing the leakage flux of the motor 1 in the high-speed region, and improving the output power of the motor 1 in the high-speed region.

[0118] 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, respectively.

[0119] According to one embodiment of this disclosure, a plurality of sets of weight-reducing holes 123 are formed on the rotor 12. Each set of weight-reducing holes 123 is disposed on the radially outer side of the corresponding first magnet slot group 120, and each set of weight-reducing holes 123 includes at least one weight-reducing hole 123. For example, multiple sets of weight-reducing holes 123 can also be provided on the rotor 12, with each set including one or more weight-reducing holes 123. The weight-reducing holes 123 can be arranged on the radially outer side of the first magnet slot group 120 in each magnetic pole. The arrangement of the weight-reducing holes 123 can disperse the stress of the rotor 12 when it rotates at high speed, avoid stress concentration at local positions on the rotor 12 and damage, and improve the service life and reliability of the rotor 12. The multiple weight-reducing holes 123 can correspond one-to-one with multiple magnetic poles, or multiple weight-reducing holes 123 can correspond to one magnetic pole. As shown in Figures 1 and 15, the arrangement of the weight-reducing holes 123 and the magnetic poles can be determined according to the actual stress distribution.

[0120] The electric powertrain 100 of some embodiments of this disclosure is briefly described below.

[0121] As shown in FIG21, the electric power assembly 100 according to some embodiments of the present disclosure includes the motor 1 in the above embodiments. Since the electric power assembly 100 according to the present disclosure is provided with the motor 1 in the above embodiments, the efficiency and NVH performance of the electric power assembly 100 can be improved after the motor 1 is installed in the electric power assembly 100.

[0122] The vehicle 1000 of some embodiments of this disclosure is briefly described below.

[0123] As shown in Figure 22, a vehicle 1000 according to some embodiments of the present disclosure includes the electric power assembly 100 in the above embodiments. Since the vehicle 1000 according to some embodiments of the present disclosure is provided with the electric power assembly 100 in the above embodiments, when the vehicle 1000 is equipped with the electric power assembly 100, the vehicle 1000 has higher NVH performance, stronger power, and higher reliability.

[0124] In the description of this disclosure, it should be understood that the terms “center,” “length,” “width,” “thickness,” “upper,” “lower,” “left,” “horizontal,” “top,” “inner,” “outer,” “axial,” “radial,” “circumferential,” etc., indicating orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, 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.

[0125] In the description of this disclosure, "first feature" and "second feature" may include one or more of the features.

[0126] In the description of this disclosure, "multiple" means two or more.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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. An electric motor, comprising: The rotor (12) and stator (11) are rotatably disposed on the inner circumference of the stator (11). An air gap (13) is formed between the stator (11) and the rotor (12). The air gap (13) is d1 in the radial direction and satisfies: 1.5mm≤d1≤3mm.

2. The motor (1) according to claim 1, wherein, The stator (11) is provided with a plurality of stator slots (112) arranged at intervals in the circumferential direction, and each stator slot (112) is provided with a flat wire winding (14).

3. The motor (1) according to claim 2, wherein, The flat wire windings (14) in each stator slot (112) are constructed to be at least 10 layers.

4. The motor (1) according to any one of claims 1 to 3, wherein, The stator (11) has a plurality of teeth (111) arranged at intervals in the circumferential direction on its inner periphery. A stator groove (112) is formed between two adjacent teeth (111) among the plurality of teeth (111). At least one of the teeth (111) has a stator auxiliary groove (113) that is recessed in the radial direction on the tooth tip facing the air gap (13).

5. The motor (1) according to claim 4, wherein, The width of the stator auxiliary groove (113) is d2, and the tooth tip width of the tooth (111) is d3, and satisfies: 1 / 3≤d2 / d3≤1 / 2.

6. The motor (1) according to claim 4 or 5, wherein, The stator auxiliary groove (113) has a radial depth of d4, and satisfies: 0.1mm≤d4≤0.3mm.

7. The motor (1) according to any one of claims 1 to 6, wherein, The rotor (12) has N magnetic poles arranged circumferentially, and satisfies: 2≤N≤8, where N is an even number; the stator (11) has N×M stator slots (112), and satisfies: M=3x, where x is a positive integer.

8. The motor (1) according to any one of claims 1 to 7, wherein, The rotor (12) is provided with a magnet. On the cross section of the rotor (12), the ratio between the area occupied by the magnet and the area of ​​the rotor (12) is a, and satisfies: 0.2≤a≤0.

25.

9. The motor (1) according to claim 8, further comprising: The rotor (12) is provided with p magnetic pole pairs, and the rotor (12) has a first magnetic slot group (120) and a second magnetic slot group (130) arranged in the radial direction. The first magnet slot group (120) includes a first magnet slot (121) and a second magnet slot (122). In the first magnet slot group (120), 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 (12) is α1, where α1 = (k1 × 180°) / p. The second magnet slot group (130) includes a third magnet slot (131) and a fourth magnet slot (132). In the second magnet slot group (130), 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 (12) is α2, where α2 = (k2 × 180°) / p; and satisfies: 0.3≤k1≤0.35, 0.55≤k2≤0.

65.

10. The motor (1) according to claim 9, wherein, In the first magnet slot group (120), 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; In the second magnetic steel groove group (130), a second gap is formed between the third magnetic steel groove (131) and the fourth magnetic steel groove (132), and the second gap gradually increases in the radially outward direction.

11. The motor (1) according to claim 9 or 10, 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 (12), 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 A fourth magnet (1321) is housed within the fourth magnet slot (132); Wherein, on the cross section of the rotor (12), 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.

12. The motor (1) according to any one of claims 9 to 11, wherein, The condition k2 satisfies 0.58≤k2≤0.6; the condition k1 satisfies 0.32≤k1≤0.

34.

13. The motor (1) according to any one of claims 9 to 12, wherein, The outer radial edge of the rotor (12) is formed with a rotor auxiliary groove (15) that opens outward in the radial direction. The central angle formed by the two ends of the rotor auxiliary groove (15) and the center of the rotor (12) in the circumferential direction is β, and satisfies: 1°≤β≤2°.

14. The motor (1) according to claim 13, wherein, The first magnet slot group (120) and the second magnet slot group (130) 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 (12) and the d-axis is γ, and satisfies: 0.7×α2≤γ≤0.75×α2.

15. The motor (1) according to any one of claims 9 to 14, wherein, The second magnet slot group (130) also includes a plurality of fifth magnet slots (133), which are 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.

16. The motor (1) according to claim 15, wherein, A first connecting portion (141) is formed between two adjacent fifth magnet slots (133) of the plurality of fifth magnet slots (133).

17. The motor (1) according to claim 16, wherein, The rotor (12) 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 (12) 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).

18. The motor (1) according to any one of claims 10 to 17, wherein, Multiple sets of weight-reducing holes (123) are formed on the rotor (12). The multiple sets of weight-reducing holes (123) are arranged on the radial outer side of the first magnet slot group (120). Any set of weight-reducing holes (123) includes at least one weight-reducing hole (123).

19. An electric power assembly (100), wherein, Includes the motor (1) according to any one of claims 1 to 18.

20. A vehicle (1000), wherein, Includes the electric powertrain (100) according to claim 19.

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