A wheel hub motor

Abstract

The invention provides a hub motor, which relates to the technical field of hub motors for two-wheeled vehicles. The hub motor comprises a rotor and a stator. The rotor is sleeved on the outside of the stator. Tangential magnetic steel slots are evenly arranged circumferentially inside the rotor. The tangential magnetic steel slots include tangential slot bodies and magnetic bridge grooves. The outer wall of the stator is evenly opened circumferentially with radial winding slots. The tangential magnetic steel slots and the radial winding slots satisfy the following relationship: α2=K*360° / 2p, 0.6≤K≤0.95, α1=360° / Z, α3>α1>α2, α1 represents the slot angle, α2 represents the magnetic bridge angle, α3 represents the pole angle, 2p represents the number of motors, K represents the formula coefficient, and Z represents the number of radial winding slots. The invention can not only effectively reduce magnetic steel leakage and improve the utilization rate of magnetic steel, but also has good anti-demagnetization ability, uniform magnetic field, small torque fluctuation, good running performance, high speed, sufficient power, and is suitable for high-speed electric motorcycles.

Description

Technical Field

[0001] The present invention relates to the technical field of two-wheeled wheel hub motors, and in particular to a wheel hub motor. Background Art

[0002] Hub motors are widely used as driving devices for two-wheeled electric vehicles (including electric bicycles and electric motorcycles). Existing hub motors include surface-mount hub motors and built-in hub motors. Existing surface-mount hub motors, such as Fig.14 As shown, it includes a stator, a magnetic material and a rotor outer ring are sleeved on the outer side of the stator, and the permanent magnet is bonded to the surface of the magnetic material by surface mounting. The existing surface mounted hub motor has a poor structural firmness of the permanent magnet and has a large torque fluctuation, which affects the motor operation performance.

[0003] Existing built-in wheel hub motors, such as Fig.15 As shown, it includes a stator, a magnetic conductive material and a rotor outer ring are sleeved on the outer side of the stator, a plurality of embedding grooves are circumferentially opened on the inner wall of the magnetic conductive material, a magnet is vertically embedded in each embedding groove, and the inner end of the magnet is usually exposed to the outside, which is prone to magnetic leakage, thereby resulting in a decrease in the utilization rate of the magnet. In addition, the motor armature reaction magnetic field that the magnet directly faces is relatively easy to be demagnetized under the condition of high current operation. At the same time, there is a large torque fluctuation, which affects the operating performance of the motor. Summary of the invention

[0004] The purpose of the present invention is to provide a hub motor to solve the technical problems existing in the prior art that the existing hub motors have low magnetic steel utilization, easy demagnetization, large torque fluctuations and affect the motor operation performance; the preferred technical scheme among the many technical schemes provided by the present invention can produce many technical effects; see the detailed description below.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A hub motor provided by the present invention comprises a rotor and a stator, wherein the rotor is sleeved on the outside of the stator, and tangential magnetic steel slots are uniformly arranged in the circumferential direction inside the rotor, wherein the tangential magnetic steel slots comprise a tangential slot body and a magnetic bridge slot, wherein the tangential slot body is provided with two corners adjacent to one side of the stator, and a magnetic bridge slot is provided at the position of each corner, and radial winding slots are uniformly opened in the circumferential direction on the outer wall of the stator, and the positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship:

[0007] α2=K*360° / 2p, 0.6≤K≤0.95;

[0008] α1=360° / Z;

[0009] α3>α1>α2;

[0010] Among them: α1 represents the slot angle, which is the angle between the midlines of the slot openings of two adjacent radial winding slots, α2 represents the magnetic bridge angle, which is the angle between the midlines of the two magnetic bridge grooves of the tangential magnetic steel slot, α3 represents the pole angle, which is the angle between the midlines of the gaps on both sides of the tangential magnetic steel slot, 2p represents the number of motor stages, K represents the formula coefficient, and Z represents the number of radial winding slots.

[0011] The tangential direction does not refer to the tangent direction of the outer circumference or inner circumference of the rotor, but refers to the tangent direction of the circumference of the tangential magnetic steel slot located on the rotor.

[0012] Preferably, 0.7≤K≤0.75.

[0013] Preferably, the positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship:

[0014] B1=(1.3~1.5)*B2;

[0015] Where: B1 represents the rotor yoke thickness, B2 represents the stator tooth width.

[0016] Preferably, an air gap is provided between the inner wall of the rotor and the outer wall of the stator, and the positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship:

[0017] B3=(7~9)*B4;

[0018] Among them: B3 represents the thickness of the magnetic steel, and B4 represents the width of the air gap.

[0019] Preferably, the positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship:

[0020] B5>3*B4;

[0021] B5>B6;

[0022] Wherein: B5 represents the thickness of the magnetic pole core, the thickness of the magnetic pole core is the distance between the tangential slot body and the inner wall of the rotor, and B6 represents the thickness of the magnetic bridge.

[0023] Preferably, the outer diameter of the rotor and the inner diameter of the rotor satisfy the following dimensional relationship:

[0024] R2 / R1=(0.92~0.95);

[0025] Wherein: R1 represents the outer diameter of the rotor, and R2 represents the inner diameter of the rotor.

[0026] Preferably, the outer diameter of the stator and the inner diameter of the stator satisfy the following dimensional relationship:

[0027] D2 / D1=(0.81-0.85);

[0028] Wherein: D1 represents the outer diameter of the stator, and D2 represents the inner diameter of the stator.

[0029] Preferably, the tangential magnetic steel slot is arranged to penetrate the rotor axially, and a magnetic steel matched with the tangential slot body is inserted into the tangential magnetic steel slot.

[0030] Preferably, fixing rings are provided on both sides of the rotor, and both ends of the magnetic steel are respectively bonded to the two fixing rings.

[0031] Preferably, the end of the magnetic steel is bonded to the end notch of the tangential magnetic steel slot.

[0032] The hub motor provided by the present invention has at least the following beneficial effects:

[0033] The hub motor comprises a rotor and a stator, wherein the rotor is sleeved to the outside of the stator, and tangential magnetic steel slots are evenly arranged circumferentially inside the rotor, and the tangential magnetic steel slots comprise a tangential slot body and a magnetic bridge groove. The tangential slot body is provided with two corners close to the stator, and a magnetic bridge groove is provided at each corner. The outer wall of the stator is evenly provided with radial winding slots circumferentially, the tangential slot body is used to accommodate the magnetic steel, and the radial winding slot is used to accommodate the stator winding. The tangential magnetic steel slots are arranged tangentially so that the magnetic steel can face the stator. The magnetic steel is located inside the rotor and adopts a deep buried structure to prevent magnetic steel leakage, which can effectively shunt the demagnetization effect of the armature magnetic field and is beneficial to anti-demagnetization. The tangential magnetic steel slots adopt a structure in which they are adjacent to each other and distributed circumferentially, so that the magnetic field can be more uniform. At the same time, the tangential magnetic steel slots have magnetic bridge grooves, which can further prevent magnetic steel leakage on the one hand, and form a magnetic isolation bridge on the other hand to isolate the magnetic field and improve the anti-demagnetization ability of the magnetic steel corners.

[0034] The positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship: α2=K*360° / 2p, 0.6≤K≤0.95, α1=360° / Z, α3>α1>α2, α1 represents the slot angle, α2 represents the magnetic bridge angle, α3 represents the pole angle, 2p represents the number of motor stages, K represents the formula coefficient, and Z represents the number of radial winding slots. Through this relationship, the torque fluctuation is kept below 20%. The lower torque fluctuation enables the hub motor to have good operating performance.

[0035] The present invention can not only effectively reduce magnetic leakage of magnetic steel and improve the utilization rate of magnetic steel, but also has good anti-demagnetization ability, uniform magnetic field, small torque fluctuation, good operating performance, high speed, sufficient power, and is suitable for high-speed electric motorcycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a schematic diagram of the structure of the present invention;

[0038] Figure 2 It is an enlarged view of part A of the present invention;

[0039] Figure 3 It is an enlarged view of part B of the present invention;

[0040] Figure 4 It is a schematic diagram of the inner and outer diameters of the rotor and the inner and outer diameters of the stator of the present invention;

[0041] Figure 5 is a torque fluctuation curve diagram of the present invention;

[0042] Figure 6 It is the main magnetic circuit path diagram of the present invention;

[0043] Figure 7 is a leakage flux path diagram of the present invention;

[0044] Figure 8 : is a curve diagram showing the relationship between B1 / B2 and the torque per unit value of the present invention;

[0045] Fig. 9 is a curve diagram showing the relationship between B3 / B4 and performance per unit value / cost per unit value of the present invention;

[0046] Fig.10 : is a curve diagram showing the relationship between R2 / R1 and the torque per unit value of the present invention;

[0047] Fig.11 : is a curve diagram showing the relationship between D2 / D1 and the torque per unit value of the present invention;

[0048] Fig.12 It is the equivalent D / Q axis magnetic circuit trend diagram of the present invention;

[0049] Fig.13 It is a speed comparison curve diagram of the present invention and the existing surface mounted hub motor;

[0050] Fig.14 It is a structural schematic diagram of an existing surface mounted hub motor;

[0051] Fig.15 It is a structural schematic diagram of an existing built-in wheel hub motor.

[0052] Reference numerals

[0053] 1. Rotor; 11. Rotor core; 111. Tangential magnetic steel slot; 1111. Tangential slot body; 1112. Magnetic bridge groove; 12. Magnetic steel; 2. Stator; 21. Stator core; 211. Radial winding slot; 212. Stator teeth; 22. Stator winding; 3. Wheel hub; 4. Existing surface-mounted wheel hub motor; 5. Existing built-in wheel hub motor. DETAILED DESCRIPTION

[0054] The present invention provides a hub motor, such as Figure 1-Figure 3 As shown, the hub motor includes a rotor 1 , a stator 2 and a hub 3 . The rotor 1 is sleeved on the outside of the stator 2 , and the hub 3 is sleeved on the outside of the rotor 1 .

[0055] The rotor 1 includes a rotor core 11 and a magnetic steel 12. A plurality of tangential magnetic steel slots 111 adjacent to each other are arranged inside the rotor core 11. All the tangential magnetic steel slots 111 are evenly distributed along the circumference of the rotor core 11. The tangential magnetic steel slots 111 include a tangential slot body 1111 and a magnetic bridge groove 1112. The tangential slot body 1111 is arranged as a strip slot with a rectangular cross-section, which matches the size of the magnetic steel 12. The magnetic steel 12 is arranged in the tangential slot body 1111. The tangential slot body 1111 is arranged on one side adjacent to the stator 2 with two corners, and a magnetic bridge groove 1112 is arranged at each of the corners.

[0056] The stator 2 includes a stator core 21 and a stator winding 22 . The outer wall of the stator core 21 is evenly provided with radial winding slots 211 in the circumferential direction, and the stator winding 22 is arranged in the radial winding slots 211 .

[0057] On the one hand, the tangential magnetic steel slots 111 are adjacent to each other and evenly distributed circumferentially, which can make the magnetic field more uniform. On the other hand, the tangential slot body 1111 is arranged tangentially so that the magnetic steel 12 faces the stator, which can effectively prevent magnetic leakage. At the same time, the tangential magnetic steel slots 111 are located inside the rotor core 11, and the magnetic steel 12 adopts an embedded structure, which can divert the demagnetization effect of the armature magnetic field, which is beneficial to the anti-demagnetization effect of the motor.

[0058] The tangential magnetic steel slot 111 includes a magnetic bridge groove 1112 located at the corner position of the tangential slot body 1111, which can not only prevent the magnetic leakage of the magnetic steel 12 and improve the utilization rate of the magnetic steel 12, but also form a magnetic isolation bridge to isolate the magnetic field and further enhance the anti-demagnetization ability of the corner of the magnetic steel 12.

[0059] The tangential magnetic steel slots 111 and the radial winding slots 211 satisfy the following relationship:

[0060] α2=K*360° / 2p, 0.6≤K≤0.95;

[0061] α1=360° / Z;

[0062] α3>α1>α2;

[0063] Wherein: α1 represents the slot angle, which is the angle between the midlines of the slots of two adjacent radial winding slots 211, α2 represents the magnetic bridge angle, which is the angle between the midlines of the two magnetic bridge grooves 1112 of the tangential magnetic steel slot 111, α3 represents the pole angle, which is the angle between the midlines of the gaps on both sides of the tangential magnetic steel slot 111, 2p represents the number of motor stages, K represents the formula coefficient, and Z represents the number of radial winding slots 211.

[0064] like Figure 5 As shown, Figure 5 It is a line graph of the relationship between the above-mentioned dimensional relationship and the torque fluctuation value of the present invention. It can be seen from the graph that when K is between 0.6 and 0.95, the torque fluctuation value is less than 20%. Smaller torque fluctuation can obtain good operating performance.

[0065] Preferably, if Figure 5 As shown, when 0.7≤K≤0.75, the corresponding torque fluctuation value is small and less than 10%, and the operating performance is optimal.

[0066] As an optional implementation, since the saturation degree of the magnetic circuit determines the torque characteristics of the motor, in order to avoid local saturation during the entire closing process of the main magnetic circuit, the position and size of the tangential magnetic steel slot 111 and the radial winding slot 211 satisfy the following relationship:

[0067] like Figure 3 As shown, Figure 3 This is an enlarged view of part B of the present invention, which includes the positions and sizes of the tangential magnetic steel slots 111 and the radial winding slots 211.

[0068] B1=(1.3~1.5)*B2;

[0069] Where: B1 represents the rotor yoke thickness, B2 represents the stator tooth width.

[0070] like Figure 8 As shown, Figure 8 It is a line graph of the relationship between B1 / B2 and the torque per unit value. It can be seen from the figure that as the ratio of B1 to B2 increases from 1 to 1.7, the torque per unit value gradually increases and then decreases. When the ratio of B1 to B2 is between 1.3 and 1.5, the torque per unit value is relatively large, around 0.9. When the ratio of B1 to B2 is 1.4, the torque per unit value reaches the maximum. At the same speed, the torque of the motor is directly proportional to the power density. Therefore, the larger the torque per unit value, the greater the power density.

[0071] As an optional implementation, Figure 3As shown, an air gap is provided between the inner wall of the rotor 1 and the outer wall of the stator 2, and the positions and sizes of the tangential magnetic steel slots 111 and the radial winding slots 211 satisfy the following relationship:

[0072] B3=(7~9)*B4;

[0073] Among them: B3 represents the thickness of the magnetic steel, and B4 represents the width of the air gap.

[0074] According to the difference in the size of the hub 3 and the outer diameter of the stator 2, as well as the difference in the production and processing technology, the air gap width B4 is set between 0.25 and 0.5 mm.

[0075] For the application of two-wheel hub motors, the overload is generally between 4 and 5 times, so the anti-demagnetization characteristics of the magnetic steel 12 need to be supported by its thickness. The thicker the magnetic steel 12, the greater its corresponding cost. The design relationship between the aforementioned magnetic steel thickness B3 and the air gap width B4 can ensure cost-effectiveness while ensuring the anti-demagnetization effect.

[0076] like Fig. 9 As shown, Fig. 9 It is a line graph of the relationship between B3 / B4 and performance per unit value / cost per unit value. It can be seen from the graph that as the ratio of B3 to B4 increases from 3 to 11, the ratio of performance per unit value to cost per unit value gradually increases and then decreases. When the ratio of B3 to B4 is between 7 and 9, the ratio of performance per unit value to cost per unit value is above 0.8. When the ratio of B3 to B4 is 8, the ratio of performance per unit value to cost per unit value is the largest, and the cost performance is the highest at this time.

[0077] Existing surface-mounted hub motors generally adopt a design with a pole arc coefficient of 1. As the price of magnetic steel increases, the proportion of magnetic steel in the total cost is relatively high, which is not conducive to cost control. Compared with existing surface-mounted hub motors, the present application has a significant cost-effectiveness.

[0078] As an optional implementation, the positions and sizes of the tangential magnetic steel slots 111 and the radial winding slots 211 satisfy the following relationship:

[0079] B5>3*B4;

[0080] B5>B6;

[0081] Wherein: B5 represents the thickness of the magnetic pole core, which is the distance between the tangential slot body 1111 and the inner wall of the rotor 1, and B6 represents the thickness of the magnetic bridge.

[0082] Combination Figure 6 and Figure 7 Affected by the core strength and leakage flux, the magnetic bridge thickness B6 is generally set to 0.5-0.65mm based on the machining accuracy and the motor rotor strength.

[0083] In order to ensure the demagnetization effect and anti-demagnetization effect of the rotor core 11 in shunting the armature magnetic field, the magnetic steel 12 adopts an embedded structure, and the pole core thickness B5 affects the structural strength of the rotor core 11 and the anti-demagnetization characteristics of the magnetic steel 12, and its influence on the above two effects is opposite. At the same time, the smaller the size of the magnetic bridge thickness B6, the smaller the leakage flux, which is more beneficial to the motor. However, the smaller the magnetic bridge thickness B6, the more it affects the mechanical strength of the rotor 2. Through the trend of the magnetic field cloud map of the present invention, the size relationship between the air gap width B4, the pole core thickness B5 and the magnetic bridge thickness B6 is an optimal size relationship, which can improve the anti-demagnetization performance on the basis of ensuring the mechanical strength of the rotor 2.

[0084] Figure 3 B7 shown in the figure represents the slot length, which is the spacing between the slots of the radial winding slots 211, B8 represents the pole distance, which is the spacing between two adjacent tangential magnetic steel slots 111 and their adjacent two magnetic bridge grooves 1112, and B9 is the magnetic steel length. The slot length B7, the pole distance B8 and the magnetic steel length B9 are set according to the size adaptability of the aforementioned B1 to B6.

[0085] As an optional implementation, Figure 4 As shown, in order to obtain a larger power density, the outer diameter of the rotor 1 and the inner diameter of the rotor 1 satisfy the following dimensional relationship:

[0086] R2 / R1=(0.92~0.95);

[0087] Wherein: R1 represents the outer diameter of the rotor, and R2 represents the inner diameter of the rotor.

[0088] like Fig.10 As shown, Fig.10 It is a line graph of the relationship between R2 / R1 and the torque per unit value. It can be seen from the graph that when the ratio of R2 to R1 is between 0.91 and 0.95, the corresponding torque per unit value is the largest, and the corresponding power density is larger.

[0089] As an optional implementation, Figure 4 As shown, in order to further obtain a higher power density, the outer diameter of the stator 2 and the inner diameter of the stator 2 satisfy the following dimensional relationship:

[0090] D2 / D1=(0.81-0.85);

[0091] Wherein: D1 represents the outer diameter of the stator, and D2 represents the inner diameter of the stator.

[0092] like Fig.11 As shown, Fig.11It is a line graph of the relationship between D2 / D1 and the torque per unit value. It can be seen from the figure that when the ratio of D2 to D1 is between 0.81 and 0.85, the corresponding torque per unit value is the largest, and the corresponding power density is larger.

[0093] For hub motors, the weight of the entire machine directly affects the performance of the motor. The aforementioned ratio of the inner and outer diameters of the stator and the inner and outer diameters of the rotor not only effectively guarantees the torque performance of the motor, but also effectively guarantees the weight and cost of the entire machine.

[0094] As an optional implementation, Figure 1 and Figure 2 As shown, the tangential magnetic steel slot 111 is arranged to penetrate the rotor 1 axially, and a magnetic steel 12 matched with the tangential slot body 1111 is inserted into the tangential magnetic steel slot 111 .

[0095] The existing built-in wheel hub motor is usually produced by a block assembly method, firstly the magnetic steel and the rotor are assembled by a mold, and then glued and sealed. However, the batch production is complicated and difficult, and the concentricity of the rotor is difficult to ensure.

[0096] The magnetic steel 12 of the present invention adopts a plug-in structure, which can realize integral punching compared to the existing built-in wheel hub motor 5, which not only greatly reduces the use of glue, simplifies the production process, facilitates mass production, but also can effectively ensure the concentricity of the rotor.

[0097] As an optional implementation, fixing rings are provided on both sides of the rotor 1, and both ends of the magnetic steel 12 are respectively bonded to the two fixing rings.

[0098] The fixing ring is used to fix the magnetic steel 12 , and can effectively prevent the magnetic steel 12 from slipping out of the end notch of the tangential magnetic steel groove 111 .

[0099] Alternatively, there is no need to provide a fixing ring, and the end of the magnetic steel 12 is bonded to the end notch of the tangential magnetic steel slot 111 .

[0100] The inductance values ​​of the DC / AC (D / Q) axes of the existing surface-mounted hub motors are similar, and the difference is small, which is not conducive to the weak magnetic field speed expansion of the motor. However, the inductance of the DC / AC (D / Q) axes of the hub motor described in the present invention has a large difference.

[0101] like Fig.12 As shown, Fig.12 This is the trend diagram of the equivalent D / Q-axis magnetic circuit of the present invention. In the present invention, the rotor magnetic circuits of the equivalent D-axis magnetic circuit and the Q-axis magnetic circuit are quite different, and the coupling magnetic circuit is relatively small, thereby producing inconsistent AC and DC axis inductance values. The weaker the cross-coupling relationship between the D-axis magnetic circuit and the Q-axis magnetic circuit, the lower the D-axis inductance decreases. Since the D-axis inductance affects the electromagnetic speed expansion of the motor, a relatively low D-axis inductance is beneficial to the weak magnetic speed expansion of the motor.

[0102] like Fig.13 As shown, Fig.13 The figure is a comparison curve diagram of the rotational speed of the present invention and the existing surface-mounted hub motor 4 on the basis of the same magnetic flux. The ordinate in the figure is the maximum rotational speed of the motor, and the abscissa is the base speed of the motor. Different motor types have different basic rotational speeds. It can be seen from the figure that for each type of motor with different base speeds, the maximum rotational speed of the present invention is higher than the maximum rotational speed of the existing surface-mounted hub motor 4, which is about 1.4 times the rotational speed of the existing surface-mounted hub motor 4.

[0103] The invention has a large rotation speed and sufficient power and is suitable for high-speed electric motorcycles.

[0104] In the description of the present application, it should be understood that the terms "upper", "lower", "inside", "outside", "top", "bottom", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0105] In addition, in the description of the present application, “multiple” and “several” mean at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0106] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0107] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A hub motor, characterized in that: The invention comprises a rotor and a stator, wherein the rotor is sleeved to the outside of the stator, and tangential magnetic steel slots are evenly arranged inside the rotor in the circumferential direction. The rotor comprises a rotor core and magnetic steel, and a plurality of tangential magnetic steel slots adjacent to each other are arranged inside the rotor core, and all the tangential magnetic steel slots are evenly distributed along the circumference of the rotor core. The tangential magnetic steel slots comprise a tangential slot body and a magnetic bridge slot, and the tangential slot body is arranged as a strip slot with a rectangular cross section, and the tangential slot body is arranged tangentially, and the tangential slot body is arranged adjacent to one side of the stator with two corners, and a magnetic bridge slot is arranged at the position of each corner, and radial winding slots are evenly opened on the outer wall of the stator in the circumferential direction, and the positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship: α2=K*360° / 2p, 0.6≤K≤0.95; α1＝360° / Z； α3＞α1＞α2； Among them: α1 represents the slot angle, which is the angle between the midlines of the slot openings of two adjacent radial winding slots, α2 represents the magnetic bridge angle, which is the angle between the midlines of the two magnetic bridge grooves of the tangential magnetic steel slot, α3 represents the pole angle, which is the angle between the midlines of the gaps on both sides of the tangential magnetic steel slot, 2p represents the number of motor stages, K represents the formula coefficient, and Z represents the number of radial winding slots.

2. The wheel hub motor according to claim 1, characterized in that: 0.7≤K≤0.75。 3. The wheel hub motor according to claim 1, characterized in that: The positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship: B1=(1.3~1.5)*B2; Where: B1 represents the rotor yoke thickness, B2 represents the stator tooth width.

4. The wheel hub motor according to claim 3, characterized in that: An air gap is provided between the inner wall of the rotor and the outer wall of the stator, and the positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship: B3=(7~9)*B4; Among them: B3 represents the thickness of the magnetic steel, and B4 represents the width of the air gap.

5. The wheel hub motor according to claim 4, characterized in that: The positions and sizes of the tangential magnetic steel slots and the radial winding slots satisfy the following relationship: B5>3*B4; B5>B6; Wherein: B5 represents the thickness of the magnetic pole core, the thickness of the magnetic pole core is the distance between the tangential slot body and the inner wall of the rotor, and B6 represents the thickness of the magnetic bridge.

6. The wheel hub motor according to claim 1, characterized in that: The outer diameter of the rotor and the inner diameter of the rotor satisfy the following dimensional relationship: R2 / R1=(0.92~0.95); Wherein: R1 represents the outer diameter of the rotor, and R2 represents the inner diameter of the rotor.

7. The wheel hub motor according to claim 1, characterized in that: The outer diameter of the stator and the inner diameter of the stator satisfy the following dimensional relationship: D2 / D1=(0.81-0.85); Wherein: D1 represents the outer diameter of the stator, and D2 represents the inner diameter of the stator.

8. The wheel hub motor according to claim 1, characterized in that: The tangential magnetic steel slot is arranged to penetrate the rotor axially, and a magnetic steel matched with the tangential slot body is inserted into the tangential magnetic steel slot.

9. The wheel hub motor according to claim 8, characterized in that: Both sides of the rotor are provided with fixing rings, and the two ends of the magnetic steel are respectively bonded to the two fixing rings.

10. The wheel hub motor according to claim 8, characterized in that: The end of the magnetic steel is bonded to the end notch of the tangential magnetic steel slot.

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