Permanent magnet synchronous motor model prediction control method based on voltage vector expansion

Abstract

The invention discloses a permanent magnet synchronous motor model prediction control method based on voltage vector expansion, and the method comprises the following steps: obtaining dq-axis stator current, dq-axis inductance, pole pair number and permanent magnet flux linkage, and calculating an electromagnetic torque value and a torque pulsation amplitude coefficient; calculating a dynamic response time coefficient through the electromagnetic torque value, and obtaining a first voltage vector expansion level matched with the dynamic response time according to the dynamic response time coefficient; acquiring a second voltage vector expansion level matched with the torque ripple amplitude according to the torque ripple amplitude coefficient; calculating the endurance coefficient of the permanent magnet synchronous motor through the electromagnetic torque value, and obtaining a third voltage vector expansion level matched with the endurance of the permanent magnet synchronous motor according to the endurance coefficient of the permanent magnet synchronous motor; and obtaining an optimal voltage vector expansion level from the obtained three voltage vector expansion levels. The response delay of the motor is effectively reduced, the dynamic response performance of the permanent magnet synchronous motor of the unmanned aerial vehicle is remarkably improved, and the high-dynamic requirement in a complex environment is met.

Description

Technical Field

[0001] The invention relates to the technical field of voltage vector expansion of unmanned aerial vehicles, and in particular to a model predictive control method of a permanent magnet synchronous motor based on voltage vector expansion. Background Art

[0002] Permanent magnet synchronous motor (PMSM) is a highly efficient and stable motor type, which is widely used in drones, electric vehicles, wind power generation and other fields. The control performance of PMSM directly affects the efficiency, stability and endurance of these applications. Therefore, how to optimize the voltage vector expansion level of PMSM, especially in the application of drone systems, has become a research focus.

[0003] Traditional permanent magnet synchronous motor model predictive control methods usually have certain limitations in practical applications, especially in the optimization of voltage vector expansion level. Traditional motor model predictive control mostly relies on fixed voltage vector levels, which limits its adaptability in high dynamic performance requirements and complex environments. In the motor control of drones, the mutual influence between parameters such as electromagnetic torque, dynamic response time and endurance has not been fully studied. Traditional methods fail to effectively combine the changes in these parameters, resulting in the motor being unable to fully exert its performance in practical applications, especially in complex environments, where there may be problems such as low efficiency and slow response. The existing technology has not fully considered how to optimize the dynamic response time, torque pulsation amplitude and endurance of the motor by dynamically adjusting the voltage vector expansion level. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a permanent magnet synchronous motor model predictive control method based on voltage vector expansion to solve the technical problems of low adaptability, low efficiency, slow response, etc. caused by the use of fixed voltage vector levels in the prior art.

[0005] The present invention provides a permanent magnet synchronous motor model predictive control method based on voltage vector expansion, comprising the following steps:

[0006] Step 1: Obtain various operating parameters of the permanent magnet synchronous motor;

[0007] Step 2: Calculate the electromagnetic torque value and torque ripple amplitude coefficient according to the dq-axis stator current, dq-axis inductance, pole pair number and permanent magnet flux obtained in step 1;

[0008] Step 3: Calculate the dynamic response time coefficient through the electromagnetic torque value, and obtain the first voltage vector expansion level matching the dynamic response time according to the dynamic response time coefficient;

[0009] Step 4: obtaining a second voltage vector expansion level matching the torque ripple amplitude according to the torque ripple amplitude coefficient;

[0010] Step 5: Calculate the cruising range coefficient of the permanent magnet synchronous motor through the electromagnetic torque value, and obtain a third voltage vector expansion level matching the cruising range of the permanent magnet synchronous motor according to the cruising range coefficient of the permanent magnet synchronous motor;

[0011] Step 6: Obtain the optimal voltage vector expansion level from the three obtained voltage vector expansion levels, and the permanent magnet synchronous motor model predicts the control method through the optimal voltage vector expansion level.

[0012] Furthermore, in step 2, the specific formula for calculating the electromagnetic torque value is:

[0013]

[0014] Where P is the number of pole pairs; f is the permanent magnet flux; id and iq are the dq-axis stator currents; Ld and Lq are the dq-axis inductances.

[0015] Furthermore, in step 2, the specific formula for calculating the torque ripple amplitude coefficient is:

[0016]

[0017] Where P is the number of pole pairs; f is the permanent magnet flux; id and iq are the dq-axis stator currents; Ld and Lq are the dq-axis inductances; and N is the initial voltage vector expansion level.

[0018] Furthermore, in step 3, the specific formula for calculating the dynamic response time coefficient by the electromagnetic torque value is:

[0019]

[0020] Where, J is the rotor inertia; B is the damping coefficient; wr is the motor speed; Te is the electromagnetic torque value; N is the initial voltage vector expansion level; wr m is the target motor speed.

[0021] Furthermore, in step 3, the specific method of obtaining the first voltage vector extension level is:

[0022] Set the first threshold,

[0023] When the dynamic response time coefficient is less than the minimum value of the first threshold, more voltage vectors are generated through space vector modulation, the dynamic response time coefficient is recalculated, and the process returns to step 3;

[0024] When the dynamic response time coefficient is greater than the maximum value of the first threshold, adjust the value of the damping coefficient B, recalculate the dynamic response time coefficient, and return to step 3;

[0025] When the dynamic response time coefficient is within the first threshold range, the current voltage vector extension level is used as the first voltage vector extension level.

[0026] Furthermore, in step 4, the specific method for obtaining the second voltage vector extension level is:

[0027] Set the second threshold,

[0028] When the torque pulsation amplitude coefficient is less than the minimum value of the second threshold, more voltage vectors are generated by space vector modulation, the torque pulsation amplitude coefficient is recalculated, and the process returns to step 4;

[0029] When the torque pulsation amplitude coefficient is greater than the maximum value of the second threshold value, the voltage vector is reduced, the torque pulsation amplitude coefficient is recalculated, and the process returns to step 4;

[0030] When the torque ripple amplitude coefficient is within the range of the second threshold, the current voltage vector extension level is used as the second voltage vector extension level.

[0031] Furthermore, in step 5, the specific formula for calculating the endurance coefficient of the permanent magnet synchronous motor by using the electromagnetic torque value is:

[0032]

[0033] Where Te is the electromagnetic torque value; wr is the motor speed; L o is the loss coefficient; Eb is the battery capacity of the drone; id and iq are the dq axis stator currents; N is the initial voltage vector expansion level.

[0034] Furthermore, in step 5, the specific method of obtaining the third voltage vector extension level is:

[0035] Set the third threshold,

[0036] When the cruising range coefficient of the permanent magnet synchronous motor is less than the minimum value of the third threshold, more voltage vectors are generated through space vector modulation, the cruising range coefficient of the permanent magnet synchronous motor is recalculated, and the process returns to step 5;

[0037] When the cruising range coefficient of the permanent magnet synchronous motor is greater than the maximum value of the third threshold, the voltage vector is reduced, the cruising range coefficient of the permanent magnet synchronous motor is recalculated, and the process returns to step 5;

[0038] When the endurance coefficient of the permanent magnet synchronous motor is within the range of the third threshold, the current voltage vector extension level is used as the third voltage vector extension level.

[0039] Furthermore, in step 6, the calculation formula for obtaining the optimal voltage vector expansion level is:

[0040] Nzy = W1 * N1 + W2 * N2 + W3 * N3

[0041] Wherein, W1, W2, and W3 are weights, 0 < W1 < 1, 0 < W2 < 1, 0 < W3 < 1, and W1 + W2 + W3 = 1; N1, N2, and N3 are the first voltage vector expansion level, the second voltage vector expansion level, and the third voltage vector expansion level, respectively.

[0042] Advantages of the present invention:

[0043] By optimizing the dynamic response time coefficient and dynamically adjusting the first voltage vector expansion, etc., the present invention effectively reduces the response delay of the motor, significantly improves the dynamic response performance of the permanent magnet synchronous motor of the unmanned aerial vehicle, and meets the high dynamic requirements in complex environments.

[0044] By analyzing the influence of the second voltage vector expansion level on the torque ripple amplitude coefficient and combining with the optimization strategy, the present invention reduces the torque ripple amplitude, thereby improving the operation stability of the motor and avoiding mechanical vibration and energy loss.

[0045] By optimizing the endurance coefficient and dynamically adjusting the third voltage vector level, the present invention enables the motor to achieve the optimal energy distribution under different working conditions, significantly improves the endurance ability of the unmanned aerial vehicle, and is particularly suitable for long-duration flight missions.

[0046] By combining the optimization analysis of dynamic response time, torque ripple amplitude, and endurance ability, the present invention comprehensively generates the optimal vector expansion level, significantly improving the adaptability of the permanent magnet synchronous motor in complex and changeable environments. Description of the Drawings

[0047] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings. The drawings are schematic and should not be construed as imposing any limitation on the present invention. In the drawings:

[0048] Figure 1 is a schematic flowchart of a specific embodiment of the present invention. Detailed Embodiments

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] The present invention is further illustrated below in conjunction with specific embodiments. Those skilled in the art should understand that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention, and modifications to various equivalent forms of the present invention fall within the scope defined by the appended claims of this application.

[0051] like Figure 1 As shown, the present invention provides a permanent magnet synchronous motor model predictive control method based on voltage vector expansion, comprising the following steps:

[0052] Step 1: Obtain various operating parameters of the permanent magnet synchronous motor, including: rotor inertia J, permanent magnet flux f of the UAV permanent magnet synchronous motor, d-axis inductance Ld, q-axis pumping inductance Lq, d-axis stator current id, q-axis stator current iq, motor speed wr, damping coefficient B and pole pair number P;

[0053] Step 2: Calculate the electromagnetic torque value Te and the torque ripple amplitude coefficient Zjx according to the dq-axis stator current, dq-axis inductance, pole pair number and permanent magnet flux obtained in step 1;

[0054] The specific formula for calculating the electromagnetic torque value is:

[0055]

[0056] The specific formula for calculating the torque ripple amplitude coefficient is:

[0057]

[0058] Where N is the initial voltage vector expansion level;

[0059] Step 3: Calculate the dynamic response time coefficient through the electromagnetic torque value. The specific formula is:

[0060]

[0061] In the formula, wr m is the target motor speed,

[0062] And according to the dynamic response time coefficient, a first voltage vector expansion level matching the dynamic response time is obtained, and the specific method is as follows:

[0063] Set the first threshold. The first threshold is set through simulation or experiment to find a minimum dynamic response time that can ensure system stability and meet dynamic performance requirements. For small servo motors, the first threshold is usually in the range of 0.01 to 0.1 seconds. For large industrial motors, a longer dynamic response time may be required. The first threshold is set between 0.1 and 1 second. The threshold setting needs to be combined with specific application scenarios. After simulation verification, it is fine-tuned to the optimal value.

[0064] When the dynamic response time coefficient is less than the minimum value of the first threshold, it means that the voltage vector level is low and does not match the dynamic response time. More voltage vectors are generated through space vector modulation. Specifically, the initial voltage vector expansion level N is adjusted to increase the sampling frequency or subdivide the voltage vector space, so as to generate more voltage vectors in unit time. For example, the hexagonal area is divided into 6 basic vectors, N=6, and it is adjusted to N=7.2 at this time. The sub-vectors in each area are adjusted to increase by 20%, and the dynamic response time coefficient is recalculated, and the process returns to step 3.

[0065] When the dynamic response time coefficient is greater than the maximum value of the first threshold, it indicates that the voltage vector level is low and does not match the dynamic response time, the value of the damping coefficient B is adjusted, the dynamic response time coefficient is recalculated, and the process returns to step 3;

[0066] When the dynamic response time coefficient is within the first threshold range, it indicates that the voltage vector level matches the dynamic response time, and the current voltage vector expansion level is used as the first voltage vector expansion level.

[0067] Step 4: Obtain a second voltage vector expansion level matching the torque ripple amplitude according to the torque ripple amplitude coefficient. The specific method is as follows:

[0068] Set a second threshold value. The second threshold value needs to meet strict torque stability. The second threshold value should be set to a smaller range, for example, the second threshold value: 0-5%.

[0069] When the torque pulsation amplitude coefficient is less than the minimum value of the second threshold, it means that the voltage vector level is low and does not match the torque pulsation amplitude. More voltage vectors are generated through space vector modulation. Specifically, the initial voltage vector expansion level N=6, and the sub-vector is increased by 30% through space vector modulation SVPWM. At this time, N=8, and the torque pulsation amplitude coefficient is recalculated, and the return is made to step 4.

[0070] When the torque pulsation amplitude coefficient is greater than the maximum value of the second threshold value, it indicates that the voltage vector level is high and does not match the torque pulsation amplitude, and the voltage vector is reduced. For example, the initial voltage vector expansion level N=6 is adjusted to N=5.4 at this time, and the sub-vectors in each area are reduced by 10%, and the torque pulsation amplitude coefficient is recalculated, and the process returns to step 4;

[0071] When the torque pulsation amplitude coefficient is within the range of the second threshold value, it indicates that the voltage vector level matches the torque pulsation amplitude, and the current voltage vector expansion level is used as the second voltage vector expansion level;

[0072] Step 5: Calculate the endurance coefficient of the permanent magnet synchronous motor through the electromagnetic torque value. The specific calculation formula is:

[0073]

[0074] Where, L o is the loss coefficient, and the commonly used values ​​include: UAV permanent magnet synchronous motor with a motor weight of less than 300 grams: Lo = 5 ~ 20, industrial UAV permanent magnet synchronous motor with a motor weight of 300 grams to 3 kilograms: Lo = 50 ~ 150, UAV permanent magnet synchronous motor with a motor weight of more than 3 kilograms: Lo = 200 ~ 500; Eb is the battery power of the UAV;

[0075] And according to the cruising range coefficient of the permanent magnet synchronous motor, a third voltage vector expansion level matching the cruising range of the permanent magnet synchronous motor is obtained. The specific method is as follows:

[0076] Set the third threshold value, which is the range of the permanent magnet synchronous motor endurance coefficient, to ensure the energy efficiency and stability of the motor operation, simulate the endurance coefficient under different voltage vector expansion levels NNN, and take the value when the performance is stable and the energy efficiency is optimal as the threshold range.

[0077] When the permanent magnet synchronous motor cruising range coefficient is less than the minimum value of the third threshold, it means that the voltage vector level is low and does not match the cruising range of the permanent magnet synchronous motor of the drone. More voltage vectors are generated through space vector modulation. For example, the initial voltage vector expansion level N=6 is adjusted to N=7.2 at this time, and 20% of the sub-vectors are increased in each area. The permanent magnet synchronous motor cruising range coefficient is recalculated, and the process returns to step 5.

[0078] When the permanent magnet synchronous motor cruising range coefficient is greater than the maximum value of the third threshold value, it means that the voltage vector level is high and does not match the cruising range of the permanent magnet synchronous motor of the drone. The voltage vector is reduced. For example, the initial voltage vector expansion level N=7.2 is adjusted to N=6 at this time, and the sub-vectors in each area are reduced by 10%. The permanent magnet synchronous motor cruising range coefficient is recalculated, and the return to step 5 is made.

[0079] When the permanent magnet synchronous motor endurance coefficient is within the range of the third threshold value, it indicates that the voltage vector level is high and matches the endurance of the permanent magnet synchronous motor of the UAV, and the current voltage vector extension level is used as the third voltage vector extension level;

[0080] Step 6: Obtain the optimal voltage vector expansion level from the three obtained voltage vector expansion levels. The specific calculation formula is:

[0081] Nzy=W1*N1+W2*N2+W3*N3

[0082] Wherein, W1, W2, and W3 are weights, 0 < W1 < 1, 0 < W2 < 1, 0 < W3 < 1, and W1 + W2 + W3 = 1; N1, N2, and N3 are the first voltage vector expansion level, the second voltage vector expansion level, and the third voltage vector expansion level respectively. If the three levels: N1, N2, N3 have different degrees of influence on different objectives, weights are assigned according to their priorities. For example, if the improvement effect of dynamic response on performance is 40%, the influence of torque ripple on performance is 35%, and the influence on endurance is 25%, then: W1 = 0.4, W2 = 0.35, W3 = 0.25; if there is no significant priority for performance objectives, the weights can be evenly distributed: W1 = W2 = W3 = 0.33; during the current system operation, the dynamic response deviation is 10%, the torque ripple deviation is 5%, and the endurance deviation is 20%, then the weights are set as: W1 = 0.2, W2 = 0.3, W3 = 0.5.

[0083] The permanent magnet synchronous motor model is predicted by a control method through the optimal voltage vector expansion level.

[0084] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A model predictive control method for a permanent magnet synchronous motor based on voltage vector expansion, characterized in that: The steps include: Step 1: Obtain various operating parameters of the permanent magnet synchronous motor; Step 2: Calculate the electromagnetic torque value and torque ripple amplitude coefficient according to the dq-axis stator current, dq-axis inductance, pole pair number and permanent magnet flux obtained in step 1; Step 3: Calculate the dynamic response time coefficient through the electromagnetic torque value, and obtain the first voltage vector expansion level matching the dynamic response time according to the dynamic response time coefficient; Step 4: obtaining a second voltage vector expansion level matching the torque ripple amplitude according to the torque ripple amplitude coefficient; Step 5: Calculate the cruising range coefficient of the permanent magnet synchronous motor through the electromagnetic torque value, and obtain a third voltage vector expansion level matching the cruising range of the permanent magnet synchronous motor according to the cruising range coefficient of the permanent magnet synchronous motor; Step 6: Obtain the optimal voltage vector expansion level from the three obtained voltage vector expansion levels, and the permanent magnet synchronous motor model predicts the control method through the optimal voltage vector expansion level.

2. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1, characterized in that: In step 2, the specific formula for calculating the electromagnetic torque value is: Where P is the number of pole pairs; f is the permanent magnet flux; id and iq are the dq-axis stator currents; Ld and Lq are the dq-axis inductances.

3. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1 or 2, characterized in that: In step 2, the specific formula for calculating the torque ripple amplitude coefficient is: Where P is the number of pole pairs; f is the permanent magnet flux; id and iq are the dq-axis stator currents; Ld and Lq are the dq-axis inductances; and N is the initial voltage vector expansion level.

4. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1 or 2, characterized in that: In step 3, the specific formula for calculating the dynamic response time coefficient by the electromagnetic torque value is: Where, J is the rotor inertia; B is the damping coefficient; wr is the motor speed; Te is the electromagnetic torque value; N is the initial voltage vector expansion level; wr m is the target motor speed.

5. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1 or 3, characterized in that: In step 3, the specific method of obtaining the first voltage vector extension level is: Set the first threshold, When the dynamic response time coefficient is less than the minimum value of the first threshold, more voltage vectors are generated through space vector modulation, the dynamic response time coefficient is recalculated, and the process returns to step 3; When the dynamic response time coefficient is greater than the maximum value of the first threshold, adjust the value of the damping coefficient B, recalculate the dynamic response time coefficient, and return to step 3; When the dynamic response time coefficient is within the first threshold range, the current voltage vector extension level is used as the first voltage vector extension level.

6. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1, characterized in that: In step 4, the specific method of obtaining the second voltage vector extension level is: Set the second threshold, When the torque pulsation amplitude coefficient is less than the minimum value of the second threshold, more voltage vectors are generated by space vector modulation, the torque pulsation amplitude coefficient is recalculated, and the process returns to step 4; When the torque pulsation amplitude coefficient is greater than the maximum value of the second threshold value, the voltage vector is reduced, the torque pulsation amplitude coefficient is recalculated, and the process returns to step 4; When the torque ripple amplitude coefficient is within the range of the second threshold, the current voltage vector extension level is used as the second voltage vector extension level.

7. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1 or 2, characterized in that: In step 5, the specific formula for calculating the endurance coefficient of the permanent magnet synchronous motor through the electromagnetic torque value is: Where Te is the electromagnetic torque value; wr is the motor speed; L o is the loss coefficient; Eb is the battery capacity of the drone; id and iq are the dq axis stator currents; N is the initial voltage vector expansion level.

8. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1 or 7, characterized in that: In step 5, the specific method of obtaining the third voltage vector extension level is: Set the third threshold, When the endurance coefficient of the permanent magnet synchronous motor is less than the minimum value of the third threshold, more voltage vectors are generated through space vector modulation, the endurance coefficient of the permanent magnet synchronous motor is recalculated, and the process returns to step 5; When the endurance coefficient of the permanent magnet synchronous motor is greater than the maximum value of the third threshold, the voltage vectors are reduced, the endurance coefficient of the permanent magnet synchronous motor is recalculated, and the process returns to step 5; When the endurance coefficient of the permanent magnet synchronous motor is within the range of the third threshold, the current voltage vector expansion level is used as the third voltage vector expansion level.

9. The permanent magnet synchronous motor model predictive control method based on voltage vector expansion according to claim 1, characterized in that: In the said step 6, the calculation formula for obtaining the optimal voltage vector expansion level is: Nzy = W1 * N1 + W2 * N2 + W3 * N3 In the formula, W1, W2, and W3 are weights, 0 < W1 < 1, 0 < W2 < 1, 0 < W3 < 1, and W1 + W2 + W3 = 1; N1, N2, and N3 are the first voltage vector expansion level, the second voltage vector expansion level, and the third voltage vector expansion level respectively.

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