Stator auxiliary slot for reducing tooth slot torque
By adding arc-shaped auxiliary slots to the stator core teeth of the motor, the vibration and noise problems caused by the cogging effect in electric vehicle motors are solved, and the cogging torque is reduced without affecting the motor performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU XINWEI POWER TECH CO LTD
- Filing Date
- 2025-06-24
- Publication Date
- 2026-07-14
AI Technical Summary
Electric vehicle motors suffer from cogging effect, which causes vibration and noise, especially at low speeds, affecting positioning accuracy and servo performance.
Arc-shaped auxiliary slots are added to the stator core teeth of the motor. The arc length of the auxiliary slots is 0.1-0.3 times the arc length of the teeth. Three slots are set on each tooth. The cogging torque is reduced by increasing the number of fundamental frequency cycles of the cogging torque and the equivalent air gap.
It effectively reduces the cogging torque amplitude while having almost no impact on other motor performance indicators, such as back EMF and maximum torque.
Smart Images
Figure CN224502985U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of permanent magnet motor technology, specifically to a stator auxiliary slot for reducing cogging torque. Background Technology
[0002] Cogging torque is the torque generated in a permanent magnet motor when the windings are not energized, due to the interaction between the permanent magnet and the stator core. When the motor rotor rotates, the magnetic permeability changes significantly within a small range corresponding to the stator slots on both sides of the permanent magnet, causing a change in the stored energy in the magnetic field, thus generating cogging torque. This phenomenon is also known as the cogging effect.
[0003] The presence of cogging torque causes torque pulsation in the motor, leading to speed fluctuations, vibration, and noise. The impact of cogging torque is particularly severe at low speeds, significantly affecting the motor's positioning accuracy and servo performance.
[0004] Currently, electric vehicle motors typically use external rotor brushless DC motors or permanent magnet synchronous motors. Due to the presence of the cogging effect, a certain amount of vibration will be generated when riding the vehicle, and a resonance point will be formed with the whole vehicle, resulting in obvious jerking and noise at low speeds. Utility Model Content
[0005] In view of this, the purpose of this utility model is to provide a stator auxiliary slot to reduce cogging torque, so as to solve the technical problem that the motors used in electric vehicles usually adopt external rotor DC brushless motors or permanent magnet synchronous motors. Due to the existence of cogging effect, a certain vibration will be generated when the whole vehicle is riding, and a resonance point will be formed with the whole vehicle, resulting in obvious jerking and noise at low speeds.
[0006] To achieve the above objectives, this utility model employs the following technical solution:
[0007] A stator auxiliary groove for reducing cogging torque includes a rim, the rim being annular in shape, and a plurality of permanent magnets being mounted on the inner wall of the rim, the plurality of permanent magnets being fixedly distributed at equal intervals around the circumference on the inner wall of the rim.
[0008] A stator is provided in the middle of the inner ring of the rim, and a stator core is provided on the outer wall of the stator. There are a number of stator cores, and the stator cores are arranged at equal intervals around the outer surface of the stator. Each stator core has three equidistant auxiliary slots on its top surface.
[0009] As a preferred embodiment of this utility model, the auxiliary groove on each stator core tooth is three recessed arc grooves.
[0010] As a preferred embodiment of this utility model, the arc length B of the auxiliary groove is between 0.1 and 0.3 of the arc length A of the tooth.
[0011] As a preferred embodiment of this utility model, each of the stator cores has a winding on its outer wall.
[0012] As a preferred embodiment of this utility model, the stator is installed in the middle of the central shaft, and nuts are provided at both ends of the central shaft for locking and fixing.
[0013] As a preferred technical solution of this utility model, an anti-rotation plate is provided at one end of the central shaft, and the anti-rotation plate is locked and fixed at one end of the central shaft by a nut.
[0014] As a preferred technical solution of this utility model, end caps are symmetrically installed at the left and right ends of the wheel rim, and a number of screws are installed on the surface of the end cap at each end, and the surface of the end cap at each end is locked and fixed to the surface of the wheel rim by a number of screws.
[0015] As a preferred embodiment of this utility model, the outer wall of the stator is provided with lead wires, and the top end of the lead wires is provided with connectors.
[0016] The principle of reducing cogging torque by opening auxiliary slots in stator teeth in this utility model is to increase the number of fundamental frequency cycles of cogging torque, which compensates for the original slot cogging torque, thereby reducing the amplitude of total cogging torque; secondly, opening auxiliary slots also increases the equivalent air gap, which is also beneficial to reducing cogging torque.
[0017] This patent adds an auxiliary slot to the stator of an electric vehicle motor. The slot is an arc-shaped slot located at the maximum outer circle of the stator teeth. The arc length B of the auxiliary slot is between 0.1 and 0.3 times the arc length A of the teeth. An auxiliary slot is opened on each tooth.
[0018] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the external structure of the stator auxiliary groove for reducing cogging torque according to this utility model;
[0020] Figure 2 This is a partial structural schematic diagram of the stator auxiliary groove for reducing cogging torque according to this utility model;
[0021] Figure 3This is a schematic diagram of the auxiliary groove of this utility model;
[0022] Figure 4 This is a comparison diagram of the tooth groove amplitude before and after grooving in this utility model;
[0023] Figure 5 This is a comparison diagram of the tangential air gap magnetic flux density before and after slotting in this utility model.
[0024] Figure 6 This is a comparison diagram of the radial air gap magnetic flux density before and after slotting in this utility model;
[0025] Figure 7 This is a comparison diagram of the back electromotive force waveform before and after slotting in this utility model;
[0026] Figure 8 A comparison of the maximum torque before and after adding the auxiliary groove to this utility model;
[0027] In the diagram: 1. Screw; 2. End cap; 3. Rim; 4. Connector; 5. Anti-rotation plate; 6. Nut; 7. Lead wire; 8. Stator core teeth; 9. Winding; 10. Permanent magnet; 11. Auxiliary slot; 12. Stator; 13. Central shaft. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0031] In the above description of this utility model, it should be noted that the terms "one side," "the other side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0032] Furthermore, terms such as "identical" do not imply that components must be absolutely identical; minor differences are permissible. The term "perpendicular" simply means that the positional relationship between components is more perpendicular than "parallel," not that the structure must be perfectly perpendicular; a slight tilt is acceptable. Example
[0033] Please see Figure 1-8 The present invention provides a technical solution: a stator auxiliary groove for reducing cogging torque, including a rim 3, the rim 3 being annular, and a permanent magnet 10 installed on the inner wall of the rim 3. There are multiple permanent magnets 10, and the multiple permanent magnets 10 are distributed and fixed at equal intervals around the circumference on the inner wall of the rim 3.
[0034] A stator 12 is provided in the middle of the inner ring of the rim 3. A stator core tooth 8 is provided on the outer wall of the stator 12. There are a number of stator core teeth 8. The stator core teeth 8 are arranged at equal intervals on the outer circumference of the stator 12. Each stator core tooth 8 has three equidistant auxiliary grooves 11 on its top surface.
[0035] Each auxiliary groove is a concave arc groove. The auxiliary groove 11 is arc-shaped, and the arc length B of the auxiliary groove 11 is between 0.1 and 0.3 of the tooth arc length A.
[0036] The principle of reducing cogging torque by opening auxiliary slots in stator teeth is to increase the number of fundamental frequency cycles of cogging torque, which compensates for the original slot cogging torque, thereby reducing the amplitude of total cogging torque. Secondly, opening auxiliary slots also increases the equivalent air gap, which is also beneficial to reducing cogging torque.
[0037] This patent adds auxiliary slots to the stator core teeth of electric vehicle motors. These slots are arc-shaped and located at the maximum outer circle of the stator teeth. The arc length B of the auxiliary slot is between 0.1 and 0.3 times the arc length A of the tooth. Three auxiliary slots are opened on each tooth.
[0038] End caps 2 are symmetrically installed on the left and right ends of the rim 3. Several screws 1 are installed on the surface of each end cap 2, and the surface of each end cap 2 is locked and fixed to the surface of the rim 3 by several screws 1.
[0039] Additionally, taking a motor with a 54-slot stator core and an outer diameter of ∅254mm, and a 60-pole rotor magnet as an example, the motor slots are unfolded using a natural tearing method from a mold, with a slot width of 2.6mm. The relevant parameters of the motor are shown in Table 1, and a motor model was created using Ansoft Maxwell software. Three auxiliary slots with a radius of R2.1 and a fillet radius of R0.36 are cut on the surface of the stator core teeth, as shown in Table 1. Figure 1 As shown, two-dimensional field simulation analysis was performed before and after slotting, comparing four aspects: cogging torque, air gap magnetic flux density, no-load back electromotive force, and maximum torque. The comparison data are shown in the appendix of the instruction manual. Figure 4 -Instruction manual included Figure 8 As shown.
[0040] From the instruction manual Figure 4 It can be seen that the addition of auxiliary slots significantly suppresses the cogging torque. Before slotting, the amplitude of the cogging torque was 1.72 N, while after slotting, the amplitude was only 0.90 N, which is only 53% of the amplitude before slotting. (Comparison of tangential air gap magnetic flux density...) Figure 3 It can be seen that after adding the auxiliary slot, the number of cycles of the fundamental wave is significantly increased at the circle, which satisfies the mechanism of reducing cogging torque mentioned in this patent.
[0041] Comparison of radial air gap magnetic flux Figure 6 It can be seen that the grooves before and after are basically overlapping; the comparison of the no-load back electromotive force is also relevant. Figure 7 It can be observed that the back electromotive force remains almost unchanged before and after slotting; maximum load simulations were performed on both stators, as shown in the attached manual. Figure 8 As shown, the average torque before slotting is 171.26 Nm, and the average absolute deviation is 9.87 Nm; the average torque after slotting is 171.16 Nm, and the average absolute deviation is 9.65 Nm, showing almost no change; that is to say, the invention of the three auxiliary slots reduces the cogging torque while having almost no impact on the motor performance.
[0042] Example 2
[0043] Please see Figure 1-8 This is another technical solution provided by the present invention. This embodiment has the same features as the above embodiment 1, and the similarities will not be described in this embodiment. The specific differences are as follows:
[0044] Please see Figure 1-8 This is another technical solution provided by the present invention. This embodiment has the same features as the above embodiment 1, and the similarities will not be described in this embodiment. The specific differences are as follows:
[0045] A stator auxiliary slot for reducing cogging torque includes a rim 3, which is annular. A permanent magnet 10 is installed on the inner wall of the rim 3. Multiple permanent magnets 10 are provided and are fixedly distributed at equal intervals around the circumference on the inner wall of the rim 3.
[0046] A stator 12 is provided in the middle of the inner ring of the rim 3. A stator core tooth 8 is provided on the outer wall of the stator 12. There are a number of stator core teeth 8. The stator core teeth 8 are arranged at equal intervals on the outer circumference of the stator 12. Three auxiliary grooves 11 are opened on the top surface of each stator core tooth 8.
[0047] The principle of reducing cogging torque by opening auxiliary slots in stator teeth is to increase the number of fundamental frequency cycles of cogging torque, which compensates for the original slot cogging torque, thereby reducing the amplitude of total cogging torque. Secondly, opening auxiliary slots also increases the equivalent air gap, which is also beneficial to reducing cogging torque.
[0048] This patent adds an auxiliary slot to the stator of an electric vehicle motor. The slot is an arc-shaped slot located at the maximum outer circle of the stator teeth. The arc length B of the auxiliary slot is between 0.1 and 0.3 times the arc length A of the teeth. An auxiliary slot is opened on each tooth.
[0049] Each stator core tooth 8 has a winding 9 on its outer wall.
[0050] The stator 12 is installed in the middle of the central shaft 13, and nuts 6 are provided at both ends of the central shaft 13 for locking and fixing.
[0051] An anti-rotation plate 5 is provided at one end of the central shaft 13, and the anti-rotation plate 5 is locked and fixed at one end of the central shaft (13) by a nut (6).
[0052] The outer wall of the stator 12 is provided with lead wires 7, and the top of the lead wires 7 is provided with connectors 4.
[0053] In addition, taking a motor with a stator core of 54 slots and an outer diameter of ∅254mm and a rotor with 60 poles as an example, the slots of this motor are unfolded by a natural tearing method using a mold, with a slot width of 2.6mm. The relevant parameters of the motor are shown in Table 1, and a motor model was created using Ansoft Maxwell software. Three auxiliary slots with a radius of R2.1 and a fillet radius of R0.36 are cut on the stator surface, as shown in Table 1. Figure 1 As shown, two-dimensional field simulation analysis was performed before and after slotting, comparing four aspects: cogging torque, air gap magnetic flux density, no-load back electromotive force, and maximum torque. The comparison data are shown in the appendix of the instruction manual. Figure 4 -Instruction manual included Figure 8 As shown.
[0054] From the instruction manual Figure 4It can be seen that the addition of auxiliary slots significantly suppresses the cogging torque. Before slotting, the amplitude of the cogging torque was 1.72 N, while after slotting, the amplitude was only 0.90 N, which is only 53% of the amplitude before slotting. (Comparison of tangential air gap magnetic flux density...) Figure 3 It can be seen that after adding the auxiliary slot, the number of cycles of the fundamental wave is significantly increased at the circle, which satisfies the mechanism of reducing cogging torque mentioned in this patent.
[0055] Comparison of radial air gap magnetic flux Figure 6 It can be seen that the grooves before and after are basically overlapping; the comparison of the no-load back electromotive force is also relevant. Figure 7 It can be observed that the back electromotive force remains almost unchanged before and after slotting; maximum load simulations were performed on both stators, as shown in the attached manual. Figure 8 As shown, the average torque before slotting is 171.26 Nm, and the average absolute deviation is 9.87 Nm; the average torque after slotting is 171.16 Nm, and the average absolute deviation is 9.65 Nm, showing almost no change; that is to say, the invention of the three auxiliary slots reduces the cogging torque while having almost no impact on the motor performance.
[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.
Claims
1. A stator auxiliary groove for reducing cogging torque, comprising a rim (3), characterized in that: The rim (3) is annular, and a permanent magnet (10) is installed on the inner wall of the rim (3). There are multiple permanent magnets (10), and the multiple permanent magnets (10) are fixedly distributed at equal intervals around the inner wall of the rim (3). The inner ring of the rim (3) is provided with a stator (12), and the outer wall of the stator (12) is provided with stator core teeth (8). Several stator core teeth (8) are arranged at equal intervals around the outer surface of the stator (12), and each stator core tooth (8) has three equally spaced auxiliary grooves (11) on its top surface.
2. A stator auxiliary slot for reducing cogging torque according to claim 1, characterized in that: The auxiliary groove (11) on each stator core tooth (8) is three recessed arc grooves.
3. A stator auxiliary slot for reducing cogging torque according to claim 1, characterized in that: The arc length B of the auxiliary groove (11) is between 0.1 and 0.3 of the tooth arc length A.
4. A stator auxiliary slot for reducing cogging torque according to claim 1, characterized in that: Each of the stator core teeth (8) has a winding (9) on its outer wall.
5. A stator auxiliary slot for reducing cogging torque according to claim 1, characterized in that: The stator (12) is installed in the middle of the central shaft (13), and nuts (6) are provided at both ends of the central shaft (13) for locking and fixing.
6. A stator auxiliary slot for reducing cogging torque according to claim 5, characterized in that: An anti-rotation plate (5) is provided at one end of the central shaft (13), and the anti-rotation plate (5) is locked and fixed at one end of the central shaft (13) by a nut (6).
7. A stator auxiliary slot for reducing cogging torque according to claim 6, characterized in that: The left and right ends of the rim (3) are symmetrically equipped with end caps (2). Several screws (1) are installed on the surface of the end cap (2) at each end. The surface of the end cap (2) at each end is locked and fixed to the surface of the rim (3) by several screws (1).
8. A stator auxiliary slot for reducing cogging torque according to claim 7, characterized in that: The outer wall of the stator (12) is provided with a lead wire (7), and the top end of the lead wire (7) is provided with a connector (4).