A design method for torque ripple suppressor

Abstract

A design method for a torque pulsation suppressor comprises the following steps: step 1. fast Fourier transform the torque of a power system to analyze the main harmonic order causing the torque pulsation; the harmonic amplitude accounts for the percentage of the DC component; step 2. select the harmonic with the largest current amplitude; step 3. obtain the number of pole pairs of the torque pulsation suppressor for suppressing the i-th harmonic according to the power system; step 4. obtain the amplitude of the torque pulsation suppressor through the amplitude relationship; step 5. read φ MSi value; Step 6. Obtain the volume of the torque pulsation suppressor according to the power system; Step 7. Obtain the pole pair number P of the torque pulsation suppressor to suppress the i-th harmonic according to the fundamental frequency, torque and speed of the power system TPCi 、Starting angle θ si , volume V to obtain the torque pulsation suppressor; step eight. Recalculate the total harmonic distortion rate. If it is still higher than the set value, select the next harmonic with the largest amplitude to suppress it until the total harmonic distortion rate is lower than the set value.

Description

Technical Field

[0001] The invention relates to the technical field of torque pulsation suppressors, and in particular to a design method of a torque pulsation suppressor. Background Art

[0002] In recent years, with the development of manufacturing industry, the demand for high-precision and high-efficiency torque output in aerospace, industrial automation, medical equipment, precision instruments and other fields has continued to increase. The torque suppression methods of various power systems are as follows: 1. Motor torque suppression method

[0003] 1.1 Chute method

[0004] The use of skewed slots is one of the most widely used methods for suppressing torque pulsation. The stator slots are tilted by a stator pitch relative to the rotor poles, making the air gap flux a constant and eliminating the slot torque pulsation. It is impossible to completely eliminate the slot torque pulsation. Rotor eccentricity affects the effect of the skewed slots in weakening the slot torque pulsation.

[0005] 1.2 Fractional Slot Method

[0006] The cogging torque is only related to the Yth harmonic component of B. When it is equal to 1, it is called the fundamental cogging torque. The number of cogging torque pulsation cycles corresponding to one rotation of the rotor is Y. The nth cogging torque pulsation is generated by the Yth harmonic, and the number of cogging torque pulsation cycles is Y. The effective torque component of the motor is partially reduced, and the average torque output of the motor will also decrease accordingly.

[0007] 1.3 Slant Pole Method

[0008] The principles of the skewed pole method and the skewed slot method are similar, both of which eliminate the cogging torque. For permanent magnet synchronous motors and other motors, the skewed pole motor processing is difficult and costly, and the average torque will also decrease.

[0009] 2. Internal combustion engine

[0010] Internal combustion engines usually reduce torque pulsation through flywheels or vibration dampers, but this significantly increases the weight of the internal combustion engine and reduces output efficiency. The installation accuracy of the flywheel is high, and only a specific harmonic of the engine is suppressed.

[0011] 3. Hybrid powertrain

[0012] In a hybrid power system, the interaction between the internal combustion engine and the motor may make the torque harmonics more complex. Traditional devices and methods for eliminating torque pulsation cannot handle the torque pulsation of the hybrid power system well. Summary of the invention

[0013] The technical problem to be solved by the present invention is to provide a design method for a torque pulsation suppressor.

[0014] The technical solution adopted by the present invention to solve the technical problem is:

[0015] A method for designing a torque ripple suppressor comprises the following steps:

[0016] Step 1. Perform Fast Fourier Transform (FFT) on the torque of the power system, and analyze the main harmonics causing torque pulsation in the power system in descending order according to the amplitude; the percentage of harmonic amplitude to DC component;

[0017] Step 2. Select the harmonic with the largest current amplitude from the main harmonic orders;

[0018] Step 3. Obtain torque ripple suppressor suppression based on power system The pole pairs of the subharmonics;

[0019] Step 4. Obtain the amplitude of all harmonics through the FFT result;

[0020] Step 5. Read through FFT results The value of torque ripple suppressor is obtained Subharmonic starting angle ;

[0021] Step 6. Obtain the volume of the torque pulsation suppressor according to the power system;

[0022] Step 7. According to the power system base frequency, power system torque, power system speed, torque pulsation suppressor suppression Pole pairs of subharmonics , torque ripple suppressor suppresses Subharmonic starting angle and torque ripple suppressor volume A torque ripple suppressor is obtained;

[0023] Step 8. Connect the obtained torque pulsation suppressor in series with the power system, and recalculate whether the total harmonic distortion rate is lower than the set value. If it is still higher than the set value, select the next harmonic with the largest amplitude for suppression until the total harmonic distortion rate is lower than the set value.

[0024] In one embodiment, the main harmonic order is , , , …, .

[0025] In one embodiment, the harmonic amplitude accounts for a percentage of the DC component of , , , …, .

[0026] In one embodiment, the torque ripple suppressor in step 3 suppresses The pole pair relationship of subharmonics is as follows:

[0027] (1)

[0028] In the formula, is the base frequency of the power system, The main harmonic order that causes torque pulsation in the power system , , , …, One of them, is the speed of the power system, Torque ripple suppressor The number of pole pairs of the subharmonics.

[0029] In one embodiment, the amplitude relationship in step 4 is as follows:

[0030] (2)

[0031] In the formula, is the power system torque Subharmonic amplitude, Torque ripple suppressor Subharmonic torque amplitude, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

[0032] In one embodiment, the torque amplitude of the torque pulsation suppressor is obtained by the amplitude relationship to be close to the amplitude of the harmonic to be eliminated, suppressing The torque amplitude relationship of the torque ripple suppressor affected by subharmonics is as follows:

[0033] (3)

[0034] In the formula, is the power system torque Subharmonic amplitude, is the DC component of the power system torque, is the percentage of harmonic amplitude to DC component , , , …, One of them.

[0035] In one embodiment, in step five, the torque ripple suppressor suppresses Subharmonic starting angle From the phase relationship:

[0036] (4)

[0037] Get torque ripple suppressor to suppress Subharmonic starting angle for ;

[0038] In the formula, Torque ripple suppressor The phase of the subharmonics, Torque ripple suppressor The pole pairs of the subharmonics, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

[0039] In one embodiment, the volume relationship of the torque ripple suppressor in step six is ​​as follows:

[0040] (5)

[0041] In the formula, is the torque density, Torque ripple suppressor Subharmonic torque, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

[0042] In one embodiment, a plurality of torque ripple suppressors are connected in series with the powertrain system.

[0043] In one embodiment, the powertrain includes an electric machine and an internal combustion engine.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The torque pulsation suppressor designed in the present invention can be applicable to power systems of different types and parameters, has a wide application range, low technical difficulty, and good torque pulsation suppression effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a torque per unit value diagram after suppressing the fundamental wave of the present invention;

[0047] Figure 2The torque per unit value diagram of the invention for suppressing the fundamental wave, the second harmonic and the sixth harmonic;

[0048] Figure 3 It is a schematic diagram of the steps of the present invention. DETAILED DESCRIPTION

[0049] The present invention is further described below in conjunction with the accompanying drawings and embodiments. Example

[0050] like Figure 1-3 As shown, this embodiment includes the following steps:

[0051] Step 1. Perform fast Fourier transform (FFT) on the torque of the power system, and sort the amplitudes from large to small to analyze the main harmonics causing the torque pulsation of the power system: , , , …, ; The percentage of harmonic amplitude to DC component is , , , …, ;

[0052] Step 2. From the main harmonic order , , , …, Select the harmonic with the largest current amplitude;

[0053] Step 3. Obtain torque ripple suppressor suppression based on power system Pole pairs of subharmonics, torque ripple suppressor suppression The pole pair relationship of subharmonics is as follows:

[0054] (1)

[0055] In the formula, is the base frequency of the power system, The main harmonic order that causes torque pulsation in the power system , , , …, One of them, is the speed of the power system, Torque ripple suppressor suppresses The number of pole pairs of the subharmonics.

[0056] Step 4. Obtain the amplitudes of all harmonics through the FFT results. The amplitude relationship is as follows:

[0057] (2)

[0058] In the formula, is the power system torque Subharmonic amplitude, Torque ripple suppressor Subharmonic torque amplitude, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

[0059] Through the amplitude relationship, the torque amplitude of the torque pulsation suppressor is close to the amplitude of the harmonic that needs to be eliminated, suppressing The torque amplitude relationship of the torque ripple suppressor affected by subharmonics is as follows:

[0060] (3)

[0061] In the formula, is the power system torque Subharmonic amplitude, is the DC component of the power system torque, is the percentage of harmonic amplitude to DC component , , , …, One of them.

[0062] Step 5. Read through FFT results The value of is given by the phase relationship:

[0063] (4)

[0064] Get torque ripple suppressor to suppress Subharmonic starting angle for ;

[0065] In the formula, Torque ripple suppressor suppresses The phase of the subharmonics, Torque ripple suppressor suppresses The pole pairs of the subharmonics, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

[0066] Step 6. Obtain the volume of the torque pulsation suppressor based on the power system. The volume relationship of the torque pulsation suppressor is as follows:

[0067] (5)

[0068] In the formula, is the torque density, Torque ripple suppressor Subharmonic torque, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

[0069] Step 7. According to the power system base frequency, power system torque, power system speed, torque pulsation suppressor suppression Pole pairs of subharmonics , torque ripple suppressor suppresses Subharmonic starting angle and torque ripple suppressor volume A torque ripple suppressor is obtained;

[0070] Step 8. Connect the obtained torque pulsation suppressor in series with the power system, and recalculate whether the total harmonic distortion rate is lower than the set value. If it is still higher than the set value, select the next harmonic with the largest amplitude for suppression until the total harmonic distortion rate is lower than the set value.

[0071] In this embodiment, the power system includes an electric motor and an internal combustion engine.

[0072] In one embodiment, a plurality of torque ripple suppressors are connected in series with the powertrain system.

[0073] Taking a permanent magnet synchronous motor with 9 pole pairs, 216 slots and a speed of 640rpm as an example, FFT analysis is performed, as shown in the following table;

[0074] harmonic The percentage of harmonic amplitude to DC component angle Fundamental (Fnd) 1.95% -68.4° Second harmonic (h2) 0.35% -82.3° Third harmonic (h3) 0.05% -18.0° Fourth harmonic (h4) 0.40% -76.0° Fifth harmonic (h5) 0.02% 73.7° Sixth harmonic (h6) 0.58% 18.0°

[0075] Conduct confirmatory analyses;

[0076] After the permanent magnet synchronous motor is connected in series with the torque pulsation suppressor for suppressing the fundamental wave of the present invention, the torque per unit value is as follows: Figure 1 As shown, the torque pulsation is obviously suppressed, and FFT analysis is performed, as shown in the following table;

[0077] harmonic The percentage of harmonic amplitude to DC component angle Fundamental (Fnd) 0.12% 96.6° Second harmonic (h2) 0.35% -81.2° Third harmonic (h3) 0.05% -23.8° Fourth harmonic (h4) 0.40% -75.8° Fifth harmonic (h5) 0.02% 86.2° Sixth harmonic (h6) 0.58% 18.0°

[0078] The amplitude of the fundamental wave is reduced from 1.95% to 0.12%, which greatly reduces the impact of the fundamental wave on the torque, and the amplitudes of other harmonics have no obvious changes.

[0079] The number of pole pairs of the torque ripple suppressor for suppressing the fundamental wave group is 9 (9p), the number of pole pairs of the torque ripple suppressor for suppressing the second harmonic group is 18 (18p), and the number of pole pairs of the torque ripple suppressor for suppressing the sixth harmonic group is 54 (54p). Fnd is the fundamental wave, h2 is the second harmonic, and h6 is the sixth harmonic.

[0080] The results of the harmonic amplitudes and total harmonic distortion (THD) of the permanent magnet synchronous motor, the motor with each harmonic suppressed individually, and the motor with each harmonic suppressed superimposedly are shown in the following table;

[0081] DC=100% Fn h2 h4 h6 h12 THD(%) Raw torque 1.95 0.35 0.4 0.58 0.45 2.16 9p (inhibits Fnd) 0.12 0.35 0.4 0.58 0.45 0.94 18p (inhibits h2) 1.94 0.06 0.4 0.58 0.45 2.12 54p (inhibits h6) 1.94 0.35 0.4 0.09 0.45 2.07 9p+18p (inhibits Fnd+h2) 0.12 0.06 0.4 0.58 0.45 0.87 9p+54p (inhibits Fnd+h6) 0.12 0.35 0.4 0.09 0.45 0.74 9p+18p+54p (inhibits Fnd+h2+h6) 0.12 0.06 0.4 0.09 0.45 0.65

[0082] like Figure 2 As shown in the figure, the corresponding suppressed harmonic amplitudes are greatly reduced, the peak-to-peak value of torque pulsation is reduced from 6.2% to 1.7%, and THD is reduced from 2.16% to 0.65%. The results prove that the device can suppress specific harmonic orders and thus reduce torque pulsation.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the technical solutions of the present invention have been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a torque ripple suppressor, characterized in that: The following steps are involved: Step 1. Perform Fast Fourier Transform (FFT) on the torque of the power system, and analyze the main harmonics causing torque pulsation in the power system by sorting them from large to small in amplitude; the percentage of harmonic amplitude to DC component; Step 2. Select the harmonic with the largest current amplitude from the main harmonic orders; Step 3. Obtain torque ripple suppressor suppression based on power system The pole pairs of the subharmonics; Step 4. Obtain the amplitude of all harmonics through the FFT result; Step 5. Read through FFT results The value of torque ripple suppressor is obtained Subharmonic starting angle ; Step 6. Obtain the volume of the torque pulsation suppressor according to the power system; Step 7. According to the power system base frequency, power system torque, power system speed, torque pulsation suppressor suppression Pole pairs of subharmonics , torque ripple suppressor suppresses Subharmonic starting angle and torque ripple suppressor volume A torque ripple suppressor is obtained; Step 8. Connect the obtained torque pulsation suppressor in series with the power system, and recalculate whether the total harmonic distortion rate is lower than the set value. If it is still higher than the set value, select the next harmonic with the largest amplitude for suppression until the total harmonic distortion rate is lower than the set value.

2. The design method of the torque ripple suppressor according to claim 1, characterized in that: The main harmonic order is , , , …, .

3. The design method of the torque ripple suppressor according to claim 2, characterized in that: The harmonic amplitude accounts for the percentage of the DC component , , , …, .

4. The design method of the torque ripple suppressor according to claim 3 is characterized in that: The torque ripple suppressor in step 3 suppresses The pole pair relationship of subharmonics is as follows: （1） In the formula, is the base frequency of the power system, The main harmonic order that causes torque pulsation in the power system , , , …, One of them, is the speed of the power system, Torque ripple suppressor The number of pole pairs of the subharmonics.

5. The design method of the torque ripple suppressor according to claim 4, characterized in that: The amplitude relationship in step 4 is as follows: （2） In the formula, is the power system torque Subharmonic amplitude, Torque ripple suppressor Subharmonic torque amplitude, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

6. The design method of the torque ripple suppressor according to claim 5, characterized in that: Through the amplitude relationship, the torque amplitude of the torque pulsation suppressor is close to the amplitude of the harmonic that needs to be eliminated, suppressing The torque amplitude relationship of the torque ripple suppressor affected by subharmonics is as follows: （3） In the formula, is the power system torque Subharmonic amplitude, is the DC component of the power system torque, is the percentage of harmonic amplitude to DC component , , , …, One of them.

7. The design method of the torque ripple suppressor according to claim 6, characterized in that: In the step 5, the torque ripple suppressor suppresses Subharmonic starting angle From the phase relationship: （4） Get torque ripple suppressor to suppress Subharmonic starting angle for ; In the formula, Torque ripple suppressor The phase of the subharmonics, Torque ripple suppressor The pole pairs of the subharmonics, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

8. The method for designing a torque ripple suppressor according to claim 7, characterized in that: The volume relationship of the torque pulsation suppressor in step 6 is as follows: （5） In the formula, is the torque density, Torque ripple suppressor Subharmonic torque, The main harmonic order that causes torque pulsation in the power system , , , …, One of them.

9. The design method of the torque ripple suppressor according to claim 8, characterized in that: A plurality of torque ripple suppressors are connected in series with the power system.

10. The method for designing a torque ripple suppressor according to claim 9, characterized in that: The power system includes an electric motor and an internal combustion engine.

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