A method for suppressing motor torque ripple based on tangential electromagnetic force compensation

Abstract

This invention relates to a method for suppressing motor torque ripple based on tangential electromagnetic force compensation, belonging to the field of permanent magnet motor technology. The method includes: simulating an initial motor to obtain the output torque waveform and calculating the initial torque ripple; determining the number of rotor pole pairs based on the initial motor structure and equally dividing the rotor modules circumferentially; calculating a set of possible rotor module numbers based on the number of rotor pole pairs and sorting the values ​​from smallest to largest; sequentially selecting rotor module numbers according to the sorting and performing an offset operation; and calculating the motor torque ripple after the odd-numbered rotor modules are offset relative to their initial positions by the offset angle when the offset angle is output, under the current rotor module number value; continuing until the torque ripple is less than the initial torque ripple, and then outputting the current rotor module number value and the offset angle; thus achieving tangential electromagnetic force specific harmonic compensation, thereby effectively suppressing motor torque ripple.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor technology, and is specifically designed for applications where the requirements for motor torque ripple are stringent, such as electric locomotives and ship propulsion. Specifically, it relates to a method for suppressing motor torque ripple based on tangential electromagnetic force compensation. Background Technology

[0002] Permanent magnet motors are widely used in the electrification of transportation, agricultural equipment, and other fields due to their advantages such as high torque density, high power density, and high efficiency. However, the torque pulsation problem caused by unavoidable local saturation during motor operation hinders the further large-scale application of permanent magnet motors.

[0003] Existing Chinese technologies, such as Chinese Patent Application No. 202510097257.1, disclose a Halbach array-type permanent magnet assisted synchronous reluctance motor rotor structure. This structure uses a three-layer magnetic barrier design, dividing each layer of permanent magnets into several segments. By adjusting the angle between each segment of permanent magnets, the magnetization direction is changed, forming a Halbach array to reduce pulsation. However, the introduction of multiple magnetic barriers often requires a large rotor space, leading to a reduction in the volume of the permanent magnets and consequently a decrease in the output torque of the permanent magnet motor. Chinese Patent Application No. 202211010878.4 discloses a method that segments the motor axially and reduces torque pulsation by rotating different rotor segments by specific mechanical angles to achieve peak-valley compensation between the output torque waveforms of different rotor segments. However, this method increases the difficulty of motor manufacturing and is difficult to apply to motors with short axial lengths. Therefore, there is an urgent need for a motor torque pulsation suppression method based on tangential electromagnetic force compensation to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing methods for suppressing torque ripple in permanent magnet motors and to propose a method for suppressing motor torque ripple based on tangential electromagnetic force compensation. By analyzing the key tangential electromagnetic force harmonic frequencies, the motor rotor topology is modularized, and specific tangential electromagnetic force harmonic compensation is achieved by precisely offsetting some rotor modules, thereby effectively reducing motor torque ripple.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for suppressing motor torque ripple based on tangential electromagnetic force compensation, comprising the following steps:

[0006] The initial motor output torque was obtained through simulation using finite element method software. Waveform, and calculate initial torque ripple. ;

[0007] Determine the number of rotor pole pairs based on the initial motor structure. The rotor modules N are divided equally along the circumference, and the set of values ​​for the number of rotor modules is calculated based on the number of rotor pole pairs, and the values ​​are sorted from smallest to largest.

[0008] The offset operation is performed by sequentially selecting the number of rotor modules according to the sorted order. When outputting the offset angle, the torque ripple of the motor is calculated after the odd-numbered rotor modules are offset from their initial positions, given the current number of rotor modules. This process continues until the torque ripple is less than the initial torque ripple, at which point the current number of rotor modules and the offset angle are output. The offset operation includes:

[0009] S1, offset the odd-numbered rotor modules relative to their initial positions by an angle. Set to 0;

[0010] S2, Based on the initial position offset angle Given the current number of rotor modules, calculate the harmonic order k of the highest amplitude harmonic component and its initial harmonic amplitude T. k0 ;

[0011] S3. Calculate the transition offset angle based on the harmonic order;

[0012] S4. Based on the transition offset angle and the current number of rotor modules, calculate the harmonic amplitude of the corresponding highest amplitude harmonic component. When the harmonic amplitude is greater than the initial harmonic amplitude, assign the current transition offset angle to the offset angle relative to the initial position and repeat S2-S3. When the harmonic amplitude is less than the initial harmonic amplitude, output the offset angle.

[0013] Preferably, the initial torque pulsation = (initial maximum motor output torque - initial minimum motor output torque) / average value of initial motor output torque * 100%.

[0014] Preferably, the number N of the rotor modules satisfies the following constraint:

[0015] ;

[0016] The number of rotor modules, N, is an even number, N=2b;

[0017] Where a and b are positive integers, This represents the number of rotor pole pairs of the motor.

[0018] Preferably, in S2, finite element software is used to simulate and obtain the current number of rotor modules. With offset angle The tangential electromagnetic force of the motor below Waveform; and the tangential electromagnetic force of the motor Perform Fast Fourier Decomposition on the waveform to obtain the harmonic order k and initial harmonic amplitude of the highest amplitude harmonic component. Tangential electromagnetic force The waveform is decomposed into DC components using Fast Fourier Transform. Highest amplitude harmonic component and residual harmonic components sum;

[0019] in, The amplitude of the highest harmonic component. s is the phase; s is the order of the residual harmonic component, and its amplitude is Phase is Therefore, the tangential electromagnetic force of the motor The fast Fourier decomposition expression is:

[0020] ;

[0021] Where t is time and w is the rotational speed of the motor rotor magnetic field.

[0022] Preferably, in S3, the range of values ​​for the transition offset angle is calculated based on the harmonic order of the highest amplitude harmonic component obtained in S2; based on the range of values ​​for the transition offset angle, the offset angle is... As a design variable, minimizing the amplitude of the k-th tangential electromagnetic force harmonic is the optimization objective. The precise transition offset angle is then calculated. To reduce optimization complexity and improve computational efficiency, a single-parameter scanning method is preferred. Based on finite element simulation software, the transition offset angle corresponding to the minimum amplitude of the kth tangential electromagnetic harmonic is determined. .

[0023] Preferably, the calculation of the transition offset angle range includes:

[0024] Calculate the reference offset angle : Where k is the harmonic order of the high-amplitude harmonic component, and N r This represents the number of pole pairs on the motor rotor.

[0025] Transition offset angle The range of values ​​is: , Rounding down to the nearest decimal place same.

[0026] Preferably, in S4, the current number of rotor modules is obtained through simulation. With offset angle The tangential electromagnetic force of the motor below Waveform; and for tangential electromagnetic force The waveform is subjected to Fast Fourier Decomposition to obtain the amplitude of the kth harmonic.

[0027] Preferably, the initial motor is a V-type permanent magnet external rotor motor.

[0028] More preferably, the V-shaped permanent magnet external rotor motor includes a rotor, a stator, a shaft, an armature winding, and V-shaped permanent magnet groups; the stator is coaxially located inside the rotor, and the shaft is placed at the center of the stator; there is an air gap between the outer wall of the stator and the inner wall of the rotor; the stator includes a stator yoke and multiple stator teeth, which are evenly distributed along the circumferential direction on the outer wall of the stator yoke; an armature winding is wound on the stator teeth; multiple V-shaped permanent magnet groups are evenly distributed on the rotor, each V-shaped permanent magnet group is composed of two rectangular permanent magnets, which are arranged in a "V" shape with the opening facing the air gap side, and the inner and outer oblique directions are the length direction of the rectangle.

[0029] Beneficial effects: Based on the mapping relationship between tangential electromagnetic force and motor output torque, this invention uses tangential electromagnetic force harmonics as an intermediate variable and achieves specific harmonic compensation of tangential electromagnetic force by precisely designing the offset angle of odd-numbered rotor modules, thereby effectively suppressing motor torque pulsation.

[0030] The torque ripple suppression method proposed in this invention achieves motor torque ripple suppression by offsetting the rotor module as a whole after the various dimensional parameters of the motor are determined. This avoids interference with the motor size design and can maintain the core loss, power factor and other performance characteristics of the motor size design.

[0031] This invention sets up an outer loop with the number of rotor modules as the variable and an inner loop with the offset angle as the variable, which are nested together. The single-parameter scanning method is used to determine the optimal offset angle within a reasonable range of the transition offset angle. This avoids the multi-parameter harmonic synchronization design in traditional designs, reduces the calculation cost and difficulty, and also avoids the dependence on advanced computing equipment in traditional designs.

[0032] This invention calculates the reference offset angle based on the harmonic distribution characteristics of tangential electromagnetic force, taking into account the effects of saturation and rotor space limitations, and calculates a reasonable range for the transition offset angle. This solves the shortcomings of repeated trial and error and wasted time in traditional torque pulsation optimization, and has strong engineering application value. Attached Figure Description

[0033] Figure 1 This is a schematic flowchart of the method of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of an example motor;

[0035] Figure 3 Example diagram of a modular motor rotor;

[0036] Figure 4 for Figure 2Output torque waveform of the motor;

[0037] Figure 5 for Figure 2 Waveform of the tangential electromagnetic force of the electric motor;

[0038] Figure 6 for Figure 5 Harmonic distribution diagram of the tangential electromagnetic force waveform;

[0039] Figure 7 The result of the offset angle optimization is shown in the figure;

[0040] Figure 8 To optimize the tangential electromagnetic force waveform;

[0041] Figure 9 The harmonic distribution diagram of the optimized tangential electromagnetic force waveform;

[0042] Figure 10 The output torque waveform of the optimized motor;

[0043] The diagram is labeled as follows: 1. Rotor; 2. Stator; 3. Shaft; 4. Armature winding; 5. V-shaped magnet assembly; 1.1. First rotor module; 1.2. Second rotor module; 2.1. Stator yoke; 2.2. Stator teeth; 5.1. Rectangular permanent magnet. Detailed Implementation

[0044] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one method for suppressing motor torque ripple based on tangential electromagnetic force compensation or several specific implementations of this invention, and does not strictly limit the scope of protection specifically claimed by this invention.

[0045] The technical solution adopted in this invention is as follows: Figure 1 As shown, a method for suppressing motor torque ripple based on tangential electromagnetic force compensation includes the following steps:

[0046] Step 1: Use finite element software to simulate and obtain the initial motor output torque. Waveform, and calculate initial torque ripple. Initial torque pulsation The calculation method is as follows: First, calculate the output torque. The average value will output torque The difference between the maximum and minimum values ​​accounts for a certain percentage of the output torque. The percentage of the average value is the initial torque ripple. ;

[0047] Step 2: Determine the number of rotor pole pairs based on the initial motor structure. And divide the rotor into N modules equally along the circumference;

[0048] Step 3: Calculate a reasonable value for the number of rotor modules N; and assign it to the appropriate values ​​in ascending order. ;

[0049] To ensure that all rotor modules have identical geometry, the number of rotor modules N should be a divisor of the number of rotor poles. The value of the number of rotor modules N satisfies the following constraint:

[0050] ;

[0051] The number of rotor modules, N, is an even number, such as N=2b;

[0052] Where a and b are positive integers, This represents the number of pole pairs on the motor rotor.

[0053] Step 4: Set the outer loop count i to 1, which represents the current number of rotor modules. ;

[0054] Step 5: Assign the initial offset angle =0;

[0055] Step 6: Using finite element software, simulate and obtain the number of rotor modules. The offset angle is tangential electromagnetic force of motor Waveform.

[0056] Step 7: Apply tangential electromagnetic force to the motor Perform Fast Fourier Decomposition on the waveform to obtain the harmonic order k and amplitude of the highest amplitude harmonic component. Tangential electromagnetic force The waveform is decomposed into DC components using Fast Fourier Transform. Highest amplitude harmonic component and residual harmonic components sum;

[0057] in, The amplitude of the highest harmonic component. s is the phase; s is the order of the residual harmonic component, and its amplitude is Phase is Therefore, the tangential electromagnetic force of the motor The fast Fourier decomposition expression is:

[0058] ;

[0059] Where t is time and w is the rotational speed of the motor rotor magnetic field.

[0060] Step 8: Based on the harmonic order k of the highest amplitude harmonic component obtained in Step 7, calculate the reference offset angle according to the following formula. : Where k is the harmonic order of the high-amplitude harmonic component, and N r This represents the number of pole pairs on the motor rotor.

[0061] Transition offset angle The range of values ​​is: , Rounding down to the nearest decimal place same.

[0062] Step 9: Determine the transition offset angle in step 8 Based on the range, with offset angle As a design variable, minimizing the amplitude of the k-th tangential electromagnetic force harmonic is the optimization objective. The precise transition offset angle is then calculated. To reduce optimization complexity and improve computational efficiency, a single-parameter scanning method is preferred. Based on finite element simulation software, the transition offset angle corresponding to the minimum amplitude of the kth tangential electromagnetic harmonic is determined. .

[0063] Step 10: Use finite element software to simulate and obtain the current number of rotor modules. With offset angle The tangential electromagnetic force of the motor below Waveform.

[0064] Step 11: Apply tangential electromagnetic force to the motor The waveform is subjected to Fast Fourier Decomposition to obtain the amplitude of the kth harmonic;

[0065] At this point, a rotor module is defined as the first rotor module 1.1, with tangential electromagnetic force. DC component The highest amplitude harmonic component and residual harmonic components The sum, expressed as:

[0066] ;

[0067] The tangential electromagnetic force generated by the second rotor module 1.2 relative to the first rotor module 1.1 DC component The highest amplitude harmonic component and residual harmonic components The sum, expressed as:

[0068] ;

[0069] Therefore, for The phase difference of the kth harmonic in the tangential electromagnetic force waveform of a rotor module is π.

[0070] In other words, when the waveforms of adjacent rotor modules are synthesized, the k-th harmonic will be compensated, and the amplitude of the synthesized harmonic will be 0; that is, the synthesized tangential electromagnetic force DC component With residual harmonic components The sum, expressed as:

[0071] ;

[0072] Synthesized tangential electromagnetic force DC component With residual harmonic components The sum, expressed as:

[0073] ;

[0074] After offset design of the odd-numbered rotor modules, the compensation effect between adjacent rotor modules successfully eliminated the highest amplitude harmonic component in the tangential electromagnetic force, namely the kth harmonic.

[0075] Step 12: Optimize the k-th harmonic amplitude of the tangential electromagnetic force And the initial tangential electromagnetic force kth harmonic amplitude in step 7 Make comparisons to determine the transition offset angle. Can it effectively reduce the amplitude of the k-th harmonic of the tangential electromagnetic force? If the amplitude of the k-th harmonic of the tangential electromagnetic force is reduced after optimization... Less than the kth harmonic amplitude of the initial tangential electromagnetic force Then determine the transition offset angle. If the amplitude of the k-th harmonic of the tangential electromagnetic force can be effectively reduced, then proceed to step 14; otherwise, if the amplitude of the k-th harmonic of the tangential electromagnetic force is not optimized... The amplitude of the kth harmonic of the initial tangential electromagnetic force is greater than the value of the initial tangential electromagnetic force. Then determine the transition offset angle. If the amplitude of the kth harmonic of the tangential electromagnetic force cannot be effectively reduced, then proceed to step 13;

[0076] Step 13: Adjust the transition offset angle Assign to the initial offset angle Then repeat steps 6-13 until the judgment result in step 12 is the transition offset angle. It can effectively reduce the amplitude of the kth harmonic of the tangential electromagnetic force until the motion stops;

[0077] Step 14: Using finite element software, simulate and obtain the number of rotor modules. The offset angle is Motor output torque Waveform, calculate the number of rotor modules as , offset is Motor torque ripple The number of rotor modules is: The offset angle is Motor torque ripple The calculation method is as follows: First, calculate the output torque. The average value will output torque The difference between the maximum and minimum values ​​accounts for a certain percentage of the output torque. The percentage of the average value is the number of rotor modules. Torque pulsation of a motor with an offset angle of α2 .

[0078] Step 15: The number of rotor modules is The offset angle is Motor torque ripple and the initial torque pulsation in step 1 By comparison, the number of rotor modules is determined to be... Can it effectively reduce torque ripple? If the number of rotor modules is... Torque pulsation of a motor with an offset angle of α2 Less than the initial torque ripple Then determine the number of rotor modules as follows: If it can effectively reduce torque ripple, then proceed to step 17; otherwise, if the number of rotor modules is... The offset angle is Motor torque ripple Greater than or equal to the initial torque ripple Then determine the number of rotor modules as follows: If the torque ripple cannot be effectively reduced, proceed to step 16;

[0079] Step 16: Assign i = i + 1, that is Assignment to the number of transition rotor modules Then repeat steps 5-16 until the result of the judgment in step 15 is the number of rotor modules. This can effectively reduce motor torque pulsation;

[0080] Step 17: Adjust the transition offset angle Assigned to offset angle , number of transition rotor modules Assign the value to the number N of rotor modules and output it.

[0081] In one specific embodiment: the initial motor is a V-type permanent magnet external rotor motor, referenced Figure 2As shown, it includes a rotor 1, a stator 2, a shaft 3, an armature winding 4, and a V-shaped permanent magnet assembly 5; the stator 2 is coaxially located inside the rotor 1, and the center of the stator 2 is used to house the shaft 3; there is an air gap between the outer wall of the stator 2 and the inner wall of the rotor 1, and the thickness of the air gap is related to the power rating of the motor, the selected permanent magnet material, and the processing and assembly technology of the rotor 1 and the stator 2.

[0082] Stator 2 is composed of stator yoke 2.1 and... The stator teeth consist of 2.2 teeth. One stator tooth 2.2 is evenly distributed along the circumferential direction on the outer wall of the stator yoke 2.1; the armature winding 4 of the motor is wound on the stator tooth 2.2; two stator teeth 2.2 are evenly distributed on the rotor. Each V-shaped permanent magnet group 5 consists of two rectangular permanent magnets 5.1. The two permanent magnets 5.1 are arranged in a "V" shape with their openings facing the air gap side, and the inner and outer diagonal directions are the length of the rectangle.

[0083] See Figure 3 The motor rotor 1 is divided into N identical rotor modules along the circumference, namely the first rotor module, the second rotor module, ..., the Nth rotor module; among the N rotor modules, the odd-numbered rotor modules rotate in the same direction by an offset angle α, while the even-numbered rotor modules remain unchanged. Figure 2 In the image, only two adjacent rotor modules are shown, namely the first rotor module 1.1 and the second rotor module 1.2, as shown below. Figure 2 As shown, the first rotor module 1.1 is offset by an angle α relative to its original position, while the second rotor module 1.2 remains unchanged in its original position;

[0084] The initial motor output torque waveform is as follows Figure 4 As shown; the horizontal axis represents the rotor position in electrical degrees; the vertical axis represents the torque in Nm. The initial motor output torque is shown when the rotor position changes from 0 to 360° in electrical degrees. It oscillates uniformly between [95.4, 110.7]; calculations show that the initial motor output torque... The average value is 103.3 Nm, the maximum value is 110.7 Nm, and the minimum value is 95.4 Nm. Therefore, the initial torque ripple (Trip0) is 14.8%.

[0085] Rotor pole pairs There are 6 reasonable values ​​for the number of rotor modules N, as shown in Table 1:

[0086] Table 1 shows the possible values ​​for the number of rotor modules N.

[0087]

[0088] After determining a reasonable value for the number of rotor modules N, considering the impact of the number of rotor modules N on the difficulty of motor assembly, priority is given to cases with fewer rotor modules. Therefore, all reasonable rotor module numbers are assigned values ​​in ascending order. , where p is a positive integer.

[0089] but:

[0090] ;

[0091] Based on the method of this invention, the number of rotor modules is obtained as follows: The offset angle is The waveform of the tangential electromagnetic force of the motor is as follows Figure 5 As shown. The horizontal axis represents the rotor position in electrical degrees; the vertical axis represents the tangential electromagnetic force in N. When the rotor position changes for one cycle from electrical degrees of 0-360°, the number of rotor modules is... The offset angle is tangential electromagnetic force of motor The waveform oscillates uniformly 6 times; Figure 6 The diagram in the middle shows the harmonic distribution of the tangential electromagnetic force. The horizontal axis represents the harmonic order, and the vertical axis represents the tangential electromagnetic force, in N. The harmonic amplitude of the tangential electromagnetic force decreases as the harmonic order increases. The highest amplitude harmonic component has a harmonic order k of 6, and its harmonic amplitude is... ;

[0092] Based on the method of this invention, the reference offset angle is calculated. If it is 1.5°, then the transition offset angle is... The range is [0.7°, 1.6°];

[0093] Based on the method of this invention, the transition offset angle of the motor is obtained. Optimization results are as follows Figure 7 As shown, the horizontal axis represents the transition offset angle. The unit is °; the vertical axis represents the amplitude of the 6th tangential electromagnetic force harmonic, in N; when the transition offset angle... When varying within the range of [0.7°, 1.6°], the amplitude of the 6th tangential electromagnetic force harmonic first decreases and then increases; among which, when the transition offset angle... Taking 1.0°, the amplitude of the 6th tangential electromagnetic force harmonic is the smallest;

[0094] Based on the method of this invention, the number of motor transition rotor modules is obtained. 2. Offset angle The waveform of the tangential electromagnetic force of the 1.0° motor is as follows: Figure 8 As shown. The horizontal axis represents the rotor position in electrical degrees; the vertical axis represents the tangential electromagnetic force in N. The number of transition rotor modules is shown when the rotor position changes throughout one cycle from electrical angle 0 to 360°. 2. Offset angle The tangential electromagnetic force of the motor is 1.0°. The waveform oscillates uniformly 6 times; Figure 9 To optimize the harmonic distribution of the tangential electromagnetic force, the horizontal axis represents the harmonic order, and the vertical axis represents the tangential electromagnetic force, in N. The amplitude of the tangential electromagnetic force harmonics decreases with increasing harmonic order; the amplitude of the 6th harmonic is shown below. ;

[0095] Based on the method of this invention, the amplitude of the sixth harmonic of the tangential electromagnetic force after motor optimization is obtained. The amplitude of the 6th harmonic of the initial tangential electromagnetic force ; Optimized tangential electromagnetic force 6th harmonic amplitude Less than the amplitude of the 6th harmonic of the initial tangential electromagnetic force Determine the transition offset angle A 1.0° angle can effectively reduce the amplitude of the 6th harmonic of the tangential electromagnetic force;

[0096] Based on the method of this invention, the number of motor transition rotor modules is obtained. 2. Offset angle The output torque waveform of the motor at 1.0° is as follows: Figure 10 The horizontal axis represents rotor position in electrical degrees; the vertical axis represents torque in Nm; the number of transition rotor modules is shown when the rotor position changes from 0 to 360° in electrical degrees. 2. Offset angle The output torque of the 1.0° motor It oscillates uniformly between [97.2, 100.5]; calculations show that the number of transition rotor modules... 2. Offset angle The motor output torque is 1.0°. The average value is 98.8 Nm, the maximum value is 100.5 Nm, and the minimum value is 97.2 Nm; therefore, the number of transition rotor modules... 2. Offset angle Torque ripple of a 1.0° motor It is 3.3%;

[0097] Based on the method of this invention, the number of motor transition rotor modules is obtained. 2. Offset angle Torque ripple of a 1.0° motor The initial torque ripple is 3.3%. The percentage was 14.8%, and the number of transition rotor modules was [missing information]. 2. Offset angle Torque ripple of a 1.0° motor Less than the initial torque ripple Determining that the number of rotor modules is 2 can effectively reduce motor torque pulsation.

[0098] In summary, the motor torque ripple suppression method of this invention: Based on the motor structure, a reasonable value for the number of rotor modules is determined. A lower number of rotor modules is given higher priority based on the difficulty of motor assembly, and the number of rotor modules is used as a design variable for the outer loop, with torque ripple being the target of the outer loop's reduction. Based on the mapping relationship between the motor output torque and torque ripple, the tangential electromagnetic force harmonic distribution is analyzed to determine that the tangential electromagnetic force harmonic with the highest amplitude harmonic component is the main cause of torque ripple, and its amplitude is used as the target of the inner loop's reduction, with the offset angle as a design variable for the inner loop. The reference offset angle is calculated based on the characteristics of the tangential electromagnetic force harmonic distribution, and the rotor saturation element is considered to calculate the transition offset angle range. Two-cycle optimization efficiently determines the number of rotor modules and the offset angle, accurately reducing the harmonic amplitude of the highest amplitude harmonic component and effectively suppressing motor torque ripple.

[0099] The embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for suppressing motor torque ripple based on tangential electromagnetic force compensation, characterized in that, Includes the following steps: Simulate the initial motor, obtain the initial motor output torque waveform, and calculate the initial torque ripple; Based on the initial motor structure, the number of rotor pole pairs is determined, and the rotor modules are equally divided along the circumference. The set of values ​​for the number of rotor modules is calculated based on the number of rotor pole pairs, and the values ​​are sorted from smallest to largest. The number of rotor modules is selected sequentially according to the sorting order to perform the offset operation. When outputting the offset angle, the torque pulsation of the motor is calculated after the odd number of rotor modules are offset from the initial position under the current number of rotor modules. Until the torque ripple is less than the initial torque ripple, output the current rotor module quantity and offset angle; the offset operation includes: S1. Set the offset angle of the odd-numbered rotor modules relative to their initial positions to 0; S2. Based on the initial position offset angle and the current number of rotor modules, calculate the harmonic order k of the highest amplitude harmonic component and its initial harmonic amplitude T. k0 ; S3. Calculate the transition offset angle based on the harmonic order; S4. Based on the transition offset angle and the current number of rotor modules, calculate the harmonic amplitude of the corresponding highest amplitude harmonic component. When the harmonic amplitude is greater than the initial harmonic amplitude, assign the current transition offset angle to the offset angle relative to the initial position and repeat S2-S3. When the harmonic amplitude is less than the initial harmonic amplitude, output the transition offset angle as the offset angle.

2. The method for suppressing motor torque ripple based on tangential electromagnetic force compensation according to claim 1, characterized in that: The initial torque pulsation = (maximum initial motor output torque - minimum initial motor output torque) / average initial motor output torque * 100%.

3. The method for suppressing motor torque ripple based on tangential electromagnetic force compensation according to claim 1, characterized in that: The number N of rotor modules satisfies the following constraint: ； The number of rotor modules, N, is an even number, N=2b; Where a and b are positive integers, This represents the number of rotor pole pairs of the motor.

4. The method for suppressing motor torque ripple based on tangential electromagnetic force compensation according to claim 1, characterized in that: In S2 and S4, the tangential electromagnetic force waveform of the motor under the corresponding rotor module number and offset angle is obtained through simulation; and the tangential electromagnetic force waveform is decomposed by fast Fourier transform to obtain the harmonic order of the highest amplitude harmonic component and its initial harmonic amplitude.

5. The method for suppressing motor torque ripple based on tangential electromagnetic force compensation according to claim 1, characterized in that: In S3, based on the harmonic order of the highest amplitude harmonic component obtained in S2, the range of values ​​for the transition offset angle is calculated; and using a single-parameter scanning method, the transition offset angle corresponding to the lowest harmonic amplitude of the highest amplitude harmonic component is calculated and determined.

6. The method for suppressing motor torque ripple based on tangential electromagnetic force compensation according to claim 5, characterized in that: The calculation of the transition offset angle range includes: Calculate the reference offset angle : Where k is the harmonic order of the high-amplitude harmonic component, and N r This represents the number of pole pairs on the motor rotor. Transition offset angle The range of values ​​is: .

7. The method for suppressing motor torque ripple based on tangential electromagnetic force compensation according to claim 1, characterized in that: The initial motor is a V-type permanent magnet external rotor motor.

8. The method for suppressing motor torque ripple based on tangential electromagnetic force compensation according to claim 7, characterized in that: The V-type permanent magnet external rotor motor includes a rotor, a stator, a shaft, an armature winding, and V-type permanent magnet groups. The stator is coaxially located inside the rotor, and the shaft is placed at the center of the stator. There is an air gap between the outer wall of the stator and the inner wall of the rotor. The stator includes a stator yoke and multiple stator teeth, which are evenly distributed along the circumferential direction on the outer wall of the stator yoke. The armature winding is wound on the stator teeth. Multiple V-type permanent magnet groups are evenly distributed on the rotor. Each V-type permanent magnet group consists of two rectangular permanent magnets arranged in a "V" shape with the opening facing the air gap side. The inner and outer oblique directions are the length direction of the rectangle.

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