Method for suppressing cogging torque of permanent magnet synchronous motor

Abstract

The invention discloses a method for suppressing cogging torque of a permanent magnet synchronous motor, which comprises the following steps of: S1, calculating the maximum common divisor according to the total number and the pole pair number of first stator slots and second stator slots of the permanent magnet synchronous motor; s2, according to the total number of the first stator slots and the second stator slots and the number of pole pairs, calculating a cogging torque period when the first stator slots and the second stator slots are uniformly distributed; s3, the deviation angle of the first groove top and the deviation angle of the first tooth boot in the unit are calculated; and S4, determining the matching of the stator slot shoe according to a calculation result, and carrying out rotation offset on the first slot top and the first tooth shoe. According to the invention, the cogging torque of the permanent magnet synchronous motor is effectively suppressed, and the overall performance of the motor can be improved without adding additional processing steps.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a method for suppressing cogging torque of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors have the advantages of high efficiency, high precision, and high torque density, and are widely used in industrial automation and transportation. Permanent magnet synchronous motors include rotors and stators. The motor can use the permanent magnets on the rotor and the electromagnetic induction of the stator to generate electromagnetic force, thereby converting mechanical energy into electrical energy or converting electrical energy into mechanical energy. However, during the operation of traditional permanent magnet synchronous motors, it is easy to generate cogging torque pulsation due to the interaction between the tooth structure of the motor stator and rotor, which will cause uneven output torque of the motor, thereby affecting the smooth operation and efficiency of the motor. Especially in situations requiring high-precision control and high efficiency, the influence of cogging torque pulsation is particularly significant.

[0003] like Figure 1 In a conventional permanent magnet synchronous motor 1, the center positions of the stator slots 111 are usually evenly distributed along the circumferential direction of the stator 11. The tooth slot structures of the stator 11 and the rotor 12 in this design will produce periodic interactions during the rotation process, thereby introducing periodic fluctuations in the output torque of the motor 1. In order to solve this problem, a variety of methods for reducing tooth slot torque pulsation have been developed, such as optimizing the shape and distribution of the stator slots, adopting fractional slot design, using special winding technology, etc. However, these methods all have the disadvantages of complex design and difficult manufacturing process, and may not achieve the desired effect in some cases. Summary of the invention

[0004] The present invention aims to simplify the motor manufacturing process and suppress the cogging torque, and provides a method for suppressing the cogging torque of a permanent magnet synchronous motor.

[0005] In order to achieve the above object, the technical solution of the present invention is: to provide a stator, comprising:

[0006] stator body;

[0007] at least one first stator slot, wherein the first stator slot is circumferentially arranged on the inner wall of the stator body, and a first slot top of the first stator slot is offset from a central axis of the corresponding first stator slot by a first angle α1 along the circumferential direction of the stator body;

[0008] at least one second stator slot, wherein the second stator slot is circumferentially disposed on an inner wall of the stator body;

[0009] at least one first tooth portion, the first tooth portion being arranged at least between two adjacent first stator slots; the first tooth portion comprising a first tooth shoe, the central axis of the first tooth shoe being offset by a second angle α2 along the circumferential direction of the stator body compared to the central axis of the first tooth portion;

[0010] At least one second tooth portion, wherein the second tooth portion is at least arranged between two adjacent second stator slots; wherein,

[0011]

[0012] Wherein, j is the number of the first stator slots; m is the greatest common divisor of the total number of the first stator slots and the second stator slots and the number of pole pairs; T c is the tooth slot torque fluctuation period when the first stator slots and the second stator slots are evenly distributed; Q is the total number of the first stator slots and the second stator slots.

[0013] The present invention also provides a permanent magnet synchronous motor, comprising:

[0014] the stator;

[0015] a rotor, the rotor being located inside the stator;

[0016] A rotating shaft, the rotating shaft being coaxially mounted inside the rotor;

[0017] An air gap is provided between the rotor and the stator.

[0018] In one embodiment, a magnetic block groove is provided on the outer wall of the rotor, and the electromagnetic block is installed in the magnetic block groove.

[0019] The present invention also provides a method for suppressing the cogging torque of a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor comprises: a stator, a rotor, a rotating shaft and an air gap; the stator comprises a stator body, at least one first stator slot, at least one second stator slot, at least one first tooth portion and at least one second tooth portion, wherein the first tooth portion comprises a first tooth shoe; the first stator slot and the second stator slot are circumferentially arranged on the inner wall of the stator body; the first tooth portion is at least arranged between two adjacent first stator slots; the second tooth portion is at least arranged between two adjacent second stator slots; the rotor is located on the inner side of the stator; the rotating shaft is coaxially installed inside the rotor; the air gap is arranged between the rotor and the stator; the method for suppressing the cogging torque of the permanent magnet synchronous motor comprises:

[0020] The first slot top of the first stator slot is offset from the center axis of the corresponding first stator slot by a first angle α1 along the circumferential direction of the stator body, and the first tooth shoe of the first tooth portion is offset along the circumferential direction of the stator body, so that the center axis of the first tooth shoe is offset from the center axis of the first tooth portion by a second angle α2 along the circumferential direction of the stator body; wherein,

[0021]

[0022]

[0023] Wherein, j is the number of the first stator slots; m is the greatest common divisor of the total number of the first stator slots and the second stator slots and the number of pole pairs in the permanent magnet synchronous motor; T c is the tooth slot torque fluctuation period when the first stator slots and the second stator slots are evenly distributed; Q is the total number of the first stator slots and the second stator slots.

[0024] In one embodiment, before the first slot top of the first stator slot is offset from the central axis of the corresponding first stator slot by a first angle α1 along the circumferential direction of the stator body, and the first tooth shoe of the first tooth portion is offset along the circumferential direction of the stator body, so that the central axis of the first tooth shoe is offset by a second angle α2 compared to the central axis of the first tooth portion along the circumferential direction of the stator body, the following steps are further included:

[0025] The greatest common divisor m of the total number of the first stator slots and the second stator slots and the number of pole pairs is obtained based on the following formula:

[0026] m = GCD(p, Q);

[0027] Wherein, Q is the total number of the first stator slots and the second stator slots, p is the number of pole pairs, and GCD represents the greatest common divisor of the two variables in the brackets.

[0028] In one embodiment, the cogging torque period T when the first stator slots and the second stator slots are evenly distributed is obtained based on the following formula: c :

[0029]

[0030] Wherein, LCM represents the least common multiple of the two variables in the brackets, Q is the total number of the first stator slots and the second stator slots, p is the number of pole pairs, and π is pi.

[0031] In one embodiment, the number of the first stator slots is the same as the number of the second stator slots.

[0032] In one embodiment, the first slot top is a portion of the first stator slot farthest from the stator, and the second slot top is a portion of the second stator slot farthest from the rotor.

[0033] In one embodiment, the second slot top of the second stator slot is located on the central axis of the second stator slot.

[0034] In one embodiment, the second tooth portion includes a second tooth shoe, and a central axis of the second tooth shoe coincides with a central axis of the second tooth portion.

[0035] In summary, the present invention provides a method for suppressing the cogging torque of a permanent magnet synchronous motor. According to the method for suppressing the cogging torque of a permanent magnet synchronous motor, the offset angle of the first slot top and the first tooth shoe is obtained, and the slot shoe matching of the stator slot is optimized on the target motor. The present invention not only effectively suppresses the cogging torque of the permanent magnet synchronous motor, but also improves the overall performance of the motor without adding additional processing steps.

[0036] In order to make the above features and advantages of the invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the structure of a traditional permanent magnet synchronous motor;

[0038] Figure 2 is a flow chart of the method of the present invention;

[0039] Figure 3 It is a schematic diagram of the stator slot shape of the permanent magnet synchronous motor changing by cooperating with the slot shoe of the stator;

[0040] Figure 4 It is a schematic diagram of comparative analysis of cogging torque fluctuation of the permanent magnet synchronous motor in the present invention;

[0041] Figure 5 Schematic diagram of comparative analysis of back-EMF waveforms of the permanent magnet synchronous motor in the present invention; DETAILED DESCRIPTION

[0042] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Figure 1 is a schematic diagram of the structure of a traditional permanent magnet synchronous motor, such as Figure 1As shown, in a conventional permanent magnet synchronous motor 1, the center positions of the stator slots 111 are usually evenly distributed along the circumference of the stator 11. The tooth slot structures of the stator 11 and the rotor 12 in this design will produce periodic interactions during the rotation process, thereby introducing periodic fluctuations in the output torque of the motor 1.

[0044] In order to simplify the motor manufacturing process and suppress the cogging torque, the following technical solutions will be adopted.

[0045] Figure 2 The present invention adopts the following technical solution: a method for optimizing the slot shoe matching of the stator slot and suppressing the tooth slot torque of the permanent magnet synchronous motor, wherein the first slot top of the first stator slot and the first tooth shoe of the first tooth portion of the conventional permanent magnet synchronous motor are respectively offset from the central axis of the corresponding first stator slot along the circumferential direction, and the specific steps are as follows:

[0046] Step S1: calculating the greatest common divisor m of the total number of the first stator slots and the second stator slots and the number of pole pairs according to the total number Q and the number of pole pairs of the permanent magnet synchronous motor;

[0047] The greatest common divisor m of the total number of the first stator slots and the second stator slots and the number of pole pairs is,

[0048] m = GCD(p, Q);

[0049] Wherein, Q is the total number of the first stator slots and the second stator slots, p is the number of pole pairs, GCD represents the greatest common divisor of the two variables in the brackets, and the number of motor slots j corresponding to each unit is,

[0050]

[0051] Step S2: Calculate the cogging torque period T when the first stator slots and the second stator slots are evenly distributed according to the total number Q and the number of pole pairs p of the first stator slots and the second stator slots. c ;

[0052] Cogging torque period T when the first stator slots and the second stator slots are evenly distributed c for,

[0053]

[0054] Among them, LCM represents the least common multiple of the two variables in the brackets;

[0055] Step S3: Calculate that the first slot top of the first stator slot is offset from the central axis of the corresponding first stator slot by a first angle α1 along the circumferential direction of the stator body; the central axis of the first tooth shoe is offset from the central axis of the first tooth portion by a second angle α2 along the circumferential direction of the stator body;

[0056] in:

[0057]

[0058] Wherein, j is the number of the first stator slots;

[0059] m is the greatest common divisor of the total number of the first stator slots and the second stator slots and the number of pole pairs;

[0060] T c is the cogging torque fluctuation period when the first stator slots and the second stator slots are evenly distributed;

[0061] Q is the total number of the first stator slots and the second stator slots;

[0062] Step S4: determining the stator slot shoe fit according to the calculation result, and offsetting the first slot top of the first stator slot and the first tooth shoe of the first tooth portion by α1 and α2 along the circumferential direction from the center axis of the corresponding first stator slot, respectively.

[0063] According to the method for suppressing the cogging torque of a permanent magnet synchronous motor, optimally, the first slot top of the first stator slot is offset by 4° from the center axis of the corresponding first stator slot along the circumferential direction of the stator structure stator, and the first tooth shoe of the first tooth portion is offset by 4° from the center axis of the corresponding first stator slot along the circumferential direction of the stator structure stator (see Figure 3 ).

[0064] To further illustrate the present invention, the following examples are given.

[0065] According to the method for suppressing the cogging torque of a permanent magnet synchronous motor, an offset angle of the first slot top of the first stator slot and the first tooth shoe of the first tooth portion is obtained to optimize the slot shoe matching of the stator slot on a target motor.

[0066] like Figure 3 As shown, the motor 2 includes a stator 21, a rotor 22, an air gap 23 and a rotating shaft 24. The rotating shaft 24 is concentrically installed inside the rotor 22. The rotor 22 is concentrically installed inside the stator 21. The air gap 23 exists between the rotor 22 and the stator 21.

[0067] The stator 21 is a hollow cylindrical structure, and includes at least one first stator slot 211, at least one second stator slot 212, at least one first tooth portion 213, at least one second tooth portion 214, and a stator body 217. The first stator slot 211 and the second stator slot 212 are both circumferentially arranged on the inner wall of the stator body 217. The second stator slot 212 and the first stator slot 211 are distributed on both sides of the central axis of the stator body 217. The first tooth portion 213 is arranged between two adjacent first stator slots 211, and the second tooth portion 214 is arranged between two adjacent second stator slots 212. The first stator slot 211 and the second stator slot 212 are evenly and discontinuously distributed on the inner wall of the stator body 217. The first stator slot 211 and the first tooth portion 213 are arranged in an annular manner in an interlaced manner, and the second stator slot 212 and the second tooth portion 214 are arranged in an annular manner in an interlaced manner.

[0068] Two windings 215 are embedded in any one of the first stator slots 211 and any one of the second stator slots 212. The first stator slot 211 includes a first slot top 2111, which is the part of the first stator slot 211 farthest from the stator body 217. The second stator slots 212 each include a second slot top 2121, which is the part of the second stator slot 212 farthest from the rotor 22. The first slot top 2111 of the first stator slot 211 is offset by 4° from the central axis of the corresponding first stator slot 211 along the circumferential direction of the stator body 217; the second slot top 2121 of the second stator slot 212 is located on the central axis of the second stator slot 212.

[0069] The first tooth portion 213 includes a first tooth shoe 2131, which is at least one portion of the outer edge of the first tooth portion 213 near the rotor 22 side extending along the circumferential direction of the stator 21; the second tooth portion 214 also includes a second tooth shoe 2141, which is at least one portion of the outer edge of the second tooth portion 214 near the rotor 22 side extending along a circumferential direction. A tooth groove structure 216 is formed between any two opposing first tooth shoes 2131 or second tooth shoes 2141.

[0070] The lengths of the first tooth shoe 2131 and the second tooth shoe 2141 are not equal; the central axis of the first tooth shoe 2131 is offset by 4° along the circumferential direction of the stator body 217 compared with the central axis of the first tooth portion 213, that is, the first tooth shoe 2131 is asymmetrically distributed along the central axis of the first tooth portion 213, one of the single-sided tooth shoes of the first tooth shoe 2131 is offset by 4° along the circumferential direction of the stator body 217, and the other single-sided tooth shoe is consistent with the length of the corresponding single-sided tooth shoe in the second tooth shoe 2141; and the central axis of the second tooth shoe 2141 coincides with the central axis of the second tooth portion 214.

[0071] In addition, the rotor 22 includes a rotor body 221, at least one magnetic block groove 222 and at least one electromagnetic block 223. The magnetic block groove 222 is evenly and discontinuously opened in the rotor body 221 on the side close to the stator 21, and the electromagnetic block 223 is installed inside the magnetic block groove 222.

[0072] Figure 3 In the structure of the motor 2 shown, only the first slot top 2111 of the first stator slot 211 is offset from the central axis of the corresponding first stator slot 211 along the circumferential direction of the stator body 217, and the first tooth shoe 2131 is offset from the central axis of the corresponding first tooth shoe 2131 along the circumferential direction of the stator body 217 compared to the central axis of the first tooth portion 213; the structure of the second stator slot 212 is the same as that in the traditional motor, and other parameters are the same as those of the traditional permanent magnet synchronous motor, and the specific parameters are shown in Table 1.

[0073] Table 1 Main parameters of permanent magnet synchronous motor

[0074]

[0075] like Figure 4 , which is a schematic diagram of torque fluctuation comparison analysis of the cogging structure in the motor 1 before optimization and the motor 2 after optimization. It can be seen that by using the method for suppressing the cogging torque of the permanent magnet synchronous motor by optimizing the slot shoes of the stator slot of the present invention, the cogging torque is reduced from 0.02Nm to 0.015Nm, which indicates that the optimization means effectively suppresses the cogging torque of the permanent magnet synchronous motor.

[0076] like Figure 5 , which is a schematic diagram of comparative analysis of the back EMF waveforms of the motor 1 before optimization and the motor 2 after optimization. It can be seen that the back EMF waveform of the motor after optimization in this application tends to be a sine wave, and the electromagnetic noise of the motor is small.

[0077] In summary, the present invention provides a method for suppressing the cogging torque of a permanent magnet synchronous motor. According to the method for suppressing the cogging torque of a permanent magnet synchronous motor, the offset angle of the first slot top 2111 and the first tooth shoe 2131 in the first tooth portion 213 is calculated, and the slot shoe matching of the stator slot is optimized on the target motor. The present invention not only effectively suppresses the cogging torque of the permanent magnet synchronous motor, but also improves the overall performance of the motor without adding additional processing steps.

[0078] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Any person having ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims

1. A stator, characterized in that: include: stator body; at least one first stator slot, wherein the first stator slot is circumferentially arranged on the inner wall of the stator body, and a first slot top of the first stator slot is offset from a central axis of the corresponding first stator slot by a first angle α1 along the circumferential direction of the stator body; at least one second stator slot, wherein the second stator slot is circumferentially disposed on an inner wall of the stator body; at least one first tooth portion, the first tooth portion being arranged at least between two adjacent first stator slots; the first tooth portion comprising a first tooth shoe, the central axis of the first tooth shoe being offset by a second angle α2 along the circumferential direction of the stator body compared to the central axis of the first tooth portion; At least one second tooth portion, wherein the second tooth portion is at least arranged between two adjacent second stator slots; wherein, Wherein, j is the number of the first stator slots; m is the greatest common divisor of the total number of the first stator slots and the second stator slots and the number of pole pairs; T c is the tooth slot torque fluctuation period when the first stator slots and the second stator slots are evenly distributed; Q is the total number of the first stator slots and the second stator slots.

2. A permanent magnet synchronous motor, characterized in that: include: A stator as claimed in claim 1; a rotor, the rotor being located inside the stator; A rotating shaft, the rotating shaft being coaxially mounted inside the rotor; An air gap is provided between the rotor and the stator.

3. The permanent magnet synchronous motor according to claim 2, characterized in that: The outer wall of the rotor is provided with a magnetic block groove, and the electromagnetic block is installed in the magnetic block groove.

4. A method for suppressing the cogging torque of a permanent magnet synchronous motor, characterized in that: The permanent magnet synchronous motor comprises: a stator, a rotor, a rotating shaft and an air gap; the stator comprises a stator body, at least one first stator slot, at least one second stator slot, at least one first tooth portion and at least one second tooth portion, the first tooth portion comprises a first tooth shoe; the first stator slot and the second stator slot are circumferentially arranged on the inner wall of the stator body; the first tooth portion is at least arranged between two adjacent first stator slots; the second tooth portion is at least arranged between two adjacent second stator slots; the rotor is located on the inner side of the stator; the rotating shaft is coaxially mounted inside the rotor; the air gap is arranged between the rotor and the stator; the method for suppressing the cogging torque of the permanent magnet synchronous motor comprises: The first slot top of the first stator slot is offset from the center axis of the corresponding first stator slot by a first angle α1 along the circumferential direction of the stator body, and the first tooth shoe of the first tooth portion is offset along the circumferential direction of the stator body, so that the center axis of the first tooth shoe is offset from the center axis of the first tooth portion by a second angle α2 along the circumferential direction of the stator body; wherein, Wherein, j is the number of the first stator slots; m is the greatest common divisor of the total number of the first stator slots and the second stator slots and the number of pole pairs in the permanent magnet synchronous motor; T c is the tooth slot torque fluctuation period when the first stator slots and the second stator slots are evenly distributed; Q is the total number of the first stator slots and the second stator slots.

5. The method for suppressing the cogging torque of a permanent magnet synchronous motor according to claim 4, characterized in that: Before the first slot top of the first stator slot is offset from the central axis of the corresponding first stator slot by a first angle α1 in the circumferential direction of the stator body, and the first tooth shoe of the first tooth portion is offset in the circumferential direction of the stator body, so that the central axis of the first tooth shoe is offset by a second angle α2 in the circumferential direction of the stator body compared with the central axis of the first tooth portion, the following steps are also included: The greatest common divisor m of the total number of the first stator slots and the second stator slots and the number of pole pairs is obtained based on the following formula: m=GCD(p,Q); Wherein, Q is the total number of the first stator slots and the second stator slots, p is the number of pole pairs, and GCD represents the greatest common divisor of the two variables in the brackets.

6. The method for suppressing the cogging torque of a permanent magnet synchronous motor according to claim 4, characterized in that: The cogging torque period T when the first stator slots and the second stator slots are evenly distributed is obtained based on the following formula: c : Wherein, LCM represents the least common multiple of the two variables in the brackets, Q is the total number of the first stator slots and the second stator slots, p is the number of pole pairs, and π is pi.

7. The method for suppressing the cogging torque of a permanent magnet synchronous motor according to claim 4, characterized in that: The number of the first stator slots is the same as the number of the second stator slots.

8. The method for suppressing the cogging torque of a permanent magnet synchronous motor according to claim 4, characterized in that: The first slot top is a portion of the first stator slot farthest from the stator, and the second slot top is a portion of the second stator slot farthest from the rotor.

9. The method for suppressing the cogging torque of a permanent magnet synchronous motor according to claim 4, characterized in that: The second slot top of the second stator slot is located on the central axis of the second stator slot.

10. The method for suppressing the cogging torque of a permanent magnet synchronous motor according to claim 9, characterized in that: The second tooth portion includes a second tooth shoe, and a central axis of the second tooth shoe coincides with a central axis of the second tooth portion.

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