Stator punching sheet and permanent magnet motor

Abstract

The utility model discloses a stator punching sheet and a permanent magnet motor. The stator punching sheet comprises an annular stator yoke part; the stator teeth are arranged at intervals along the outer circumferential surface of the stator yoke part, and a stator slot is formed between every two adjacent stator teeth; wherein the outer contour of each stator tooth comprises two straight line segments and an arc segment which is concentric with the stator yoke part, and the two straight line segments are connected with the two ends of the arc segment respectively and are symmetrically arranged relative to the center line of the stator tooth. According to the utility model, the linear sections at the two sides are introduced into the outer contour of the stator tooth and are combined with the arc section in the middle, so that the distribution of air gaps between the stator tooth and the rotor is effectively adjusted. Due to the design, the air gap magnetic density distribution is closer to a sinusoidal waveform, so that the harmonic component is reduced, and the unsmooth pulsation of the torque is reduced. Meanwhile, due to the fact that the arc section in the middle is reserved, the fundamental wave magnetic field intensity can be maintained to the maximum extent while harmonic waves are reduced, and remarkable reduction of power density is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of motors, in particular to a stator punching sheet and a permanent magnet motor. Background Art

[0002] Permanent magnet motors (PMMs) have two rotor types: inner rotor and outer rotor. Outer rotor PMMs, especially those with concentrated stator windings, are well-suited for in-wheel motors in electric vehicles. However, these motors also face technical challenges. Their high power density results in high air gap flux density and significantly high harmonic amplitudes of all orders. This can lead to uneven torque pulsation during motor operation. Therefore, there is an urgent need to design stator laminations that offer low harmonic content while maintaining high power density. Utility Model Content

[0003] The main purpose of the utility model is to provide a stator punching sheet and a permanent magnet motor to solve the above technical problems.

[0004] The purpose of the utility model can be achieved by adopting the following technical solutions:

[0005] A stator punching sheet, comprising:

[0006] an annular stator yoke;

[0007] a plurality of stator teeth, the stator teeth being arranged at intervals along the outer circumference of the stator yoke, with a stator slot being formed between two adjacent stator teeth;

[0008] Wherein, the outer profile of each stator tooth includes:

[0009] two straight line segments, and

[0010] an arc segment arranged concentrically with the stator yoke,

[0011] The two straight line segments are respectively connected to two ends of the arc segment and are symmetrically arranged relative to the center line of the stator teeth.

[0012] The stator teeth include pole shoes located on two opposite sides, and the opening of the stator slot is formed between the pole shoes of two adjacent stator teeth.

[0013] The pole shoe includes an end face facing the opening, and an arc transition is provided between the end face and the adjacent stator tooth side face.

[0014] The radius R of the arc transition and the thickness h of the pole shoe near the opening satisfy the relationship: R=kr×h, where the coefficient kr is in the range of 0.5≤kr≤2.

[0015] The actual thickness h of the pole shoe at the opening and the thickness H at the corresponding position when the outer contour of the stator tooth is a complete circular arc satisfy the relationship: h=kh×H, where the coefficient kh is in the range of 0.6≤kh≤0.9.

[0016] The angle α between the two sides of the stator slot opening satisfies the relationship: α=360° / z, where z is the number of the stator teeth.

[0017] The horizontal dimension b of the straight line segment and the outer contour width Bj of the stator tooth satisfy the relationship: b=kb×Bj, where the coefficient kb is in the range of 0.2≤kb≤0.4.

[0018] The radial width Be of the stator yoke and the root width Bc of the stator teeth satisfy the relationship: Be=ke×Bc, where the coefficient ke is in the range of 0.6≤ke≤0.9.

[0019] The root width Bc of the stator teeth and the diameter Dz of the circle passing through the center points of all the stator slots satisfy the relationship: Bc=kc×π×Dz / z, where the coefficient kc is in the range of 0.35≤kc≤0.55, and z is the number of the stator teeth.

[0020] A permanent magnet motor comprises the stator punching sheet as described above.

[0021] Beneficial technical effects of the utility model:

[0022] This utility model effectively adjusts the distribution of the air gap between the stator teeth and the rotor by introducing straight segments on both sides of the stator tooth outer contour and combining them with a circular arc segment in the middle. This design makes the air gap magnetic density distribution more sinusoidal, thereby reducing harmonic components and reducing the uneven pulsation of torque. Furthermore, by retaining the circular arc segment in the middle, this design can minimize harmonics while maintaining the fundamental magnetic field strength to the greatest extent possible, avoiding a significant decrease in power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a stator punching sheet according to an embodiment of the present utility model;

[0024] Figure 2 This is a schematic diagram of a stator punching sheet according to an embodiment of the present utility model;

[0025] Figure 3 This is an enlarged schematic diagram of the stator teeth of the stator punching sheet according to an embodiment of the present utility model;

[0026] Figure 4 This is an enlarged schematic diagram of the stator teeth of the stator punching sheet according to an embodiment of the present utility model.

[0027] Description of reference numerals:

[0028] In the figure: 10 - stator yoke, 20 - stator tooth, 20a - center line, 21 - straight line segment, 22 - arc segment, 23 - arc transition, 30 - stator slot, 31 - opening, 40 - pole shoe, 41 - end face, 50 - removed area. DETAILED DESCRIPTION

[0029] In order to make the technical solution of the present invention more clear and specific to those skilled in the art, the present invention is described in further detail below with reference to embodiments and drawings, but the implementation manner of the present invention is not limited thereto.

[0030] like Figures 1-4 As shown, the stator punching sheet provided in this embodiment includes a stator yoke 10 and a plurality of stator teeth 20 .

[0031] The stator yoke 10 is annular, specifically circular, and serves as the main structure of the stator laminations. A plurality of stator teeth 20 are evenly spaced along the outer circumference of the stator yoke 10 , with stator slots 30 formed between two adjacent stator teeth 20 .

[0032] The outer contour of each stator tooth 20 comprises two straight segments 21 and an arc segment 22. The arc segment 22 is concentric with the stator yoke 10. The two straight segments 21 connect to the ends of the arc segment 22 and are symmetrically positioned relative to the centerline 20a of the stator tooth 20. In other words, the two straight segments 21 are symmetrically positioned relative to the midpoint of the arc segment 22.

[0033] This design introduces straight segments 21 on the left and right sides of the stator tooth 20's outer contour, effectively "shaving off" portions of the traditional arc-shaped outer contour. Compared to a conventional stator tooth contour composed entirely of arc segments, this design creates an uneven distribution of the air gap between the stator tooth 20 and the rotor in these areas, resulting in a change in the magnetic flux distribution within the air gap. This change reduces the harmonic components of the air gap magnetic flux between the stator and rotor, improving the sinusoidality of the air gap magnetic flux distribution.

[0034] Because the harmonic components that cause adverse effects are primarily distributed on both sides of the tooth poles (the outer contour of the stator teeth), this design only performs linear "pole clipping" on both sides of the outer contour, retaining the arc segment 22 in the middle of the outer contour of the stator tooth 20, which is concentric with the stator yoke 10. This effectively reduces the impact of harmonics while maximizing the fundamental amplitude, thereby avoiding a decrease in power density.

[0035] This design, by introducing straight segments 21 into the outer contour of the stator teeth 20 and retaining the circular segments 22 in the middle, maximizes fundamental magnetic field strength while effectively reducing higher-order harmonic components. Consequently, motors employing this stator lamination not only maintain high power density but also improve operational smoothness and efficiency.

[0036] In this embodiment, the two ends of the arc segment 22 refer to its left end and right end, that is, one straight line segment 21 is located at the left end of the arc segment 22 , and the other straight line segment 21 is located at the right end of the arc segment 22 .

[0037] In this embodiment, the center line 20a refers to a straight line extending outward from the center of the stator punching sheet and passing through the center of the stator tooth 20. In other words, the center line 20a is a straight line extending outward from the center of the stator punching sheet and passing through the midpoint of the arc segment 22.

[0038] Specifically, the center line 20a is a straight line starting from the center of the stator punching sheet and passing through the center of the stator tooth 20 in the radial direction. Figure 3 In FIG. 2 , a partial enlarged view of a stator tooth 20 can be seen. 20 a in the figure is the center line.

[0039] In this embodiment, the two straight segments 21 are symmetrically arranged relative to the centerline 20a of the stator teeth 20. This means that the two straight segments 21 are located on either side of the centerline 20a and that their angles with the centerline 20a are equal. This design helps optimize the air gap magnetic field distribution, reduce harmonic content, and thus improve motor performance.

[0040] In this embodiment, the “two sides” in which a portion of the outer contour of the stator tooth 20 is cut off near both sides refers to the left and right sides of the outer contour of the stator tooth 20 .

[0041] In one embodiment, the stator tooth 20 includes pole shoes 40 on opposite sides. The pole shoes 40 are convex edges on the left and right sides of the stator tooth 20. The opening 31 of the stator slot 30 is formed between the pole shoes 40 of two adjacent stator teeth 20.

[0042] The pole shoe 40 includes an end surface 41 facing the opening 31 , and a circular arc transition 23 is provided between the end surface 41 and the side surface of the adjacent stator tooth 20 .

[0043] The corner between the end face 41 and the side of the stator tooth 20 forms the corner between the pole shoe 40 and the side of the stator tooth 20. Corners are prone to stress concentration points, and the arc transition 23 effectively disperses stress, improving the mechanical strength of the pole shoe 40. Furthermore, the arc transition 23 reduces local magnetic saturation and magnetic field line distribution in the pole shoe 40, resulting in greater motor output.

[0044] In this embodiment, the design of the arc transition 23 ensures that the punching sheet has sufficient structural strength even if a Hall installation slot (not shown in the drawings) needs to be opened on the stator tooth 20 .

[0045] In some embodiments, the radius R of the arc transition 23 and the thickness h of the pole piece 40 near the opening of the stator slot 30 are proportional to each other: R = kr × h, where the proportionality coefficient kr ranges from 0.5 ≤ kr ≤ 2. The kr value within this range allows designers to flexibly adjust it based on specific needs.

[0046] The proportionality factor kr determines the ratio of the fillet radius R to the thickness h of the pole shoe 40 near the stator slot 30 opening (the thickness at the tip of the pole shoe 40). Specifically, a smaller kr (closer to 0.5) means a smaller fillet radius. A larger kr (closer to 2) means a larger fillet radius, which further improves structural strength.

[0047] In a more specific embodiment, the value range of kr is 0.9 to 1.2.

[0048] In some embodiments, the actual thickness h of the pole piece 40 near the opening of the stator slot 30 is proportional to the theoretical thickness H, assuming the outer contour of the stator tooth 20 is entirely composed of arc segments 22: h = kh × H, where the proportionality factor kh ranges from 0.6 ≤ kh to 0.9. This range allows designers to flexibly adjust the kh value based on specific application requirements.

[0049] Here, H refers to the theoretical thickness of the pole shoe 40 near the opening of the stator slot 30 if the outer contour of the stator tooth 2 is entirely composed of arc segments 22 (i.e., without straight segments 21). By introducing the coefficient kh, the relationship between the actual thickness of the pole shoe 40 near the opening of the stator slot 30 and the theoretical thickness can be quantitatively described.

[0050] When kh is close to 0.9, the actual thickness h of the pole piece 40 is close to the theoretical thickness H, and the modulation effect on the air gap magnetic field is weak. When kh is close to 0.6, the actual thickness h of the pole piece 40 is significantly less than the theoretical thickness H, and the modulation effect on the air gap magnetic field is enhanced.

[0051] In this embodiment, if Figure 3 and Figure 4 As shown, the actual thickness h and theoretical thickness H here can also be regarded as height.

[0052] In a more specific embodiment, the value range of kh is 0.7 to 0.8.

[0053] In this embodiment, if Figure 4 As shown, the removed area 50 is defined as the area between the arc segment 22 and the actual straight segment 21 if both ends of the arc segment 22 are extended outward to form a complete arc. At this time, the thickness of the pole shoe 40 near the opening of the stator slot 30 is the theoretical thickness H.

[0054] In one embodiment, the angle α between two sides of the opening of the stator slot 30 satisfies the relationship: α=360° / z, where z is the number of stator teeth 20 .

[0055] By setting the angle α of the opening 31 to the size of the pole pitch (360° / z), a uniform distribution of the openings of the stator slots 30 is achieved. This design ensures that each stator slot 30 has the same geometric characteristics, which is conducive to the symmetrical arrangement of the winding and the simplification of the manufacturing process.

[0056] In one embodiment, there is a proportional relationship between the horizontal dimension b of the straight segment 21 and the outer contour width Bj of the stator tooth 20: b = kb × Bj, where the proportional coefficient kb ranges from 0.2 ≤ kb ≤ 0.4. Designers can adjust the kb value according to the requirements of specific application scenarios.

[0057] By adjusting the value of kb, the size of the area "cut off" from the straight line segment 21 can be adjusted. For example, a larger kb value can be selected for applications requiring high torque accuracy, while a smaller kb value can be selected for applications seeking maximum power output.

[0058] In this embodiment, if Figure 3 As shown, the horizontal dimension b of the straight segment 21 represents the horizontal length of the portion of the pole shoe 40 top removed by the straight segment 21. This design forms a slightly narrowed pole shoe 40 top by removing a small portion of each pole shoe 40 on both sides, with the aim of optimizing the air gap magnetic field distribution.

[0059] In some embodiments, kb is set to 0.4. A larger kb value effectively weakens the high-order harmonic components in the air gap by increasing the proportion of the straight line segment 21. This helps reduce torque ripple and improve torque smoothness and accuracy.

[0060] In some other embodiments, kb is set to 0.2. A smaller kb value means that the "cut-off" area of the straight segment 21 is smaller, and more arc segments 22 are retained. This helps to maximize the fundamental magnetic field strength, thereby improving the power output of the motor.

[0061] In one embodiment, the radial width Be of the stator yoke 10 and the root width Bc of the stator teeth 20 are proportional to each other: Be = ke × Bc, where the proportionality coefficient ke ranges from 0.6 ≤ ke ≤ 0.9. The ke value within this range allows designers to flexibly adjust it based on specific application requirements.

[0062] In this embodiment, if Figure 1 As shown, the shortest distance between the inner circle and the outer circle of the stator yoke 10 is defined as the radial width Be of the stator yoke 10 .

[0063] In this embodiment, if Figure 1 As shown, the distance between adjacent edges of adjacent stator slots 30 is defined as the root width Bc of the stator tooth 20 .

[0064] In a more specific embodiment, the value range of ke is 0.7 to 0.8.

[0065] In one embodiment, there is a proportional relationship between the root width Bc of the stator tooth 20 and the diameter Dz of the circle passing through the center points of all stator slots 30: Bc=kc×π×Dz / z, where the proportional coefficient kc is in the range of 0.35≤kc≤0.55, z is the number of stator teeth 20, and π is pi.

[0066] The kc value within this range allows designers to flexibly adjust it according to specific application requirements. For example, for high-torque density applications, a larger kc value can be selected, while for high-speed motors, a smaller kc value can be selected to reduce iron losses.

[0067] In this embodiment, if Figure 1 As shown, the circle of the center points of all stator slots 30 is an imaginary circle, the diameter Dz of which is used to calculate the root width Bc of the stator teeth 20. This circle should theoretically pass through the center points of all stator slots 30.

[0068] In a more specific embodiment, the value range of kc is 0.4 to 0.5.

[0069] In the above embodiment, the number z of the stator teeth 20 is an integer multiple of 3. In this embodiment, the number of stator teeth 20 is 48. In other embodiments, the number may be other.

[0070] In one embodiment, a motor is provided, which is a permanent magnet motor, and includes the stator punching sheet of the above embodiment. The stator punching sheet can be applied to the permanent magnet motor to fully demonstrate its advantages.

[0071] The above is only a further embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solution and concept of the present invention within the scope disclosed by the present invention, which falls within the protection scope of the present invention.

Claims

1. A stator punching sheet, characterized in that: include: an annular stator yoke (10); a plurality of stator teeth (20), the stator teeth (20) being arranged at intervals along the outer peripheral surface of the stator yoke (10), and a stator slot (30) being formed between two adjacent stator teeth (20); Wherein, the outer profile of each stator tooth (20) includes: two straight line segments (21), and a circular arc segment (22) arranged concentrically with the stator yoke (10), The two straight line segments (21) are respectively connected to two ends of the circular arc segment (22), and are symmetrically arranged relative to the center line of the stator tooth (20).

2. The stator sheet according to claim 1, characterized in that: The stator teeth (20) include pole shoes (40) located on two opposite sides, and an opening of the stator slot (30) is formed between the pole shoes (40) of two adjacent stator teeth (20).

3. The stator punching sheet according to claim 2, characterized in that: The pole shoe (40) comprises an end surface (41) facing the opening, and a circular arc transition is provided between the end surface (41) and the side surface of the adjacent stator tooth (20).

4. The stator sheet according to claim 3, characterized in that: The radius R of the arc transition and the thickness h of the pole shoe (40) near the opening satisfy the relationship: R=kr×h, wherein the coefficient kr is in the range of 0.5≤kr≤2.

5. The stator sheet according to claim 2, characterized in that: The actual thickness h of the pole shoe (40) at the opening and the thickness H at the corresponding position when the outer contour of the stator tooth (20) is a complete circular arc satisfy the relationship: h=kh×H, wherein the coefficient kh is in the range of 0.6≤kh≤0.

9.

6. The stator punching sheet according to claim 2, characterized in that: The angle α between the two sides of the stator slot (30) opening satisfies the relationship: α=360° / z, where z is the number of the stator teeth (20).

7. The stator sheet according to claim 1, characterized in that: The horizontal dimension b of the straight segment (21) and the outer contour width Bj of the stator tooth (20) satisfy the relationship: b=kb×Bj, wherein the coefficient kb is in the range of 0.2≤kb≤0.

4.

8. The stator punching sheet according to claim 1, characterized in that: The radial width Be of the stator yoke (10) and the root width Bc of the stator teeth (20) satisfy the relationship: Be=ke×Bc, wherein the coefficient ke is in the range of 0.6≤ke≤0.

9.

9. The stator punching sheet according to claim 1, characterized in that: The root width Bc of the stator teeth (20) and the diameter Dz of the circle passing through the center points of all the stator slots (30) satisfy the relationship: Bc=kc×π×Dz / z, where the coefficient kc is in the range of 0.35≤kc≤0.55, and z is the number of the stator teeth (20).

10. A permanent magnet motor, characterized in that: The invention comprises the stator punching sheet according to any one of claims 1 to 9.

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