CN109560726A - A kind of voltage vector regional selection method based on varied angle PREDICTIVE CONTROL - Google Patents

Abstract

The invention discloses a voltage vector area selection method based on variable angle predictive control. First, based on DTC predictive control, a selection area for variable angle predictive control of surface-type permanent magnet synchronous motor direct torque control is given; The selected area is divided into three equal parts to obtain three phase angle sets, and the objective function g value is calculated by the stator flux linkage amplitude and torque value; finally, the three phase angle sets are compared to analyze the surface-type permanent magnet synchronous motor direct torque control variable angle Predict the control performance of the control, complete the voltage vector area selection. The invention can simplify the selection of the system, reduce the operation time, and has certain feasibility.

Description

A Voltage Vector Region Selection Method Based on Variable Angle Predictive Control

technical field

The invention belongs to the technical field of vector selection, in particular to a voltage vector region selection method based on surface-type permanent magnet synchronous motor direct torque control variable angle predictive control.

Background technique

The direct torque control technology is based on the stator flux linkage coordinate system and directly uses the torque as the control object, which avoids a large number of calculations during the transformation of the rotation coordinate and the dependence on the motor parameters. It has good dynamic performance and short torque response time.

In the direct torque prediction control system of surface-type permanent magnet synchronous motor, an evaluation function is introduced, which comprehensively considers the torque error and stator flux error, and controls it. Space vector modulation technology is used to achieve a more ideal control effect. .

However, along with the variables and operation functions, the calculation time and complexity are increased. Therefore, a surface-type permanent magnet synchronous motor direct torque control variable angle predictive control-voltage vector selection region is proposed to optimize the performance of the control system.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a voltage vector region selection method based on variable angle predictive control to improve the performance of the permanent magnet synchronous motor direct torque control system and reduce torque pulsating, and the switching frequency is constant.

The present invention adopts following technical scheme:

A voltage vector area selection method based on variable angle predictive control. First, based on DTC predictive control, the selection area of surface-type permanent magnet synchronous motor direct torque control variable angle predictive control is given; Three phase angle sets are obtained in equal parts, and the objective function g value is calculated by the stator flux linkage amplitude and torque value; finally, the three phase angle sets are compared to analyze the control of the surface-type permanent magnet synchronous motor direct torque control variable angle predictive control control performance, complete the voltage vector area selection.

Specifically, the voltage vector selection area of the surface-type permanent magnet synchronous motor direct torque control system is as follows:

∠V ₁₁ ∈(0°,90°)

∠V ₀₁ ∈(90°,180°-δ)

∠V ₀₀ ∈(180°,270°)

∠V ₁₀ ∈(270°,360°-δ)

Among them, ∠V ₁₁ is to increase the torque and increase the interval of the stator flux linkage, ∠V ₀₁ is to increase the torque and decrease the interval of the stator flux linkage, ∠V ₀₀ is to decrease the torque and decrease the stator flux linkage The interval of ∠V ₁₀ is the interval of reducing the torque and increasing the stator flux linkage, and δ is the torque angle.

Specifically, first, the voltage vector is obtained Through the output value of the stator flux hysteresis comparator The output value τ and torque angle δ value of the torque hysteresis comparator select the interval where the voltage vector is located, and then input the stator flux linkage amplitude and torque value into the objective function g to select min(g), and find the corresponding angle voltage vector.

Further, the objective function g is calculated as follows:

The torque ripple root mean square error _{Trip_RMSE} is calculated as follows:

The flux linkage pulsation root mean square error ψ _{rip_RMSE} is calculated as follows:

Among them, n is the number of samples; T _e is the reference torque value, and ψ _s is the reference stator flux linkage amplitude.

Further, the magnitude of the stator flux linkage is calculated as follows:

The torque formula is calculated as follows:

in, is the stator flux linkage amplitude at the next moment, is the voltage vector at the current moment, is the stator flux linkage amplitude at the current moment, δ(k+1) is the torque angle at the next moment, δ(k) is the torque angle at the current moment, and T _e (k+1) is the torque angle at the next moment. moment value.

Further, choose the voltage vector magnitude for:

Among them, U _dc is the bus voltage.

Specifically, the first phase angle set is:

in, For the first phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the first phase angle set, increase the torque and reduce the alternative angle of the stator flux linkage, For the first phase angle set, reduce the torque and reduce the alternative angle of the stator flux linkage, For the first phase angle set, reduce the torque and reduce the alternative angle of the stator flux linkage, δ is the torque angle.

Specifically, the second phase angle set is:

in, For the second phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the second phase angle set, increase the torque and reduce the alternative angle of the stator flux linkage, For the second phase angle set, reduce the torque and reduce the alternative angle of the stator flux linkage, For the second phase angle set, reduce the torque and increase the alternative angle of the stator flux linkage, δ is the torque angle.

Specifically, the third phase angle set is:

in, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, δ is the torque angle.

Compared with the prior art, the present invention at least has the following beneficial effects:

The present invention is a voltage vector area selection method based on variable angle predictive control. Based on the direct torque control predictive control, the selection area of the surface type permanent magnet synchronous motor direct torque control variable angle predictive control is given, and the torque ripple and the The stator flux pulsation reduces the running time of the control system and the number of switch tables.

Further, through the output value of the stator flux linkage hysteresis comparator The output value τ and the torque angle δ value of the torque hysteresis comparator select the interval where the voltage vector is located, and then input the reference torque value and the reference stator flux linkage value into the objective function to select the minimum value, so as to select the optimal voltage vector .

Further, according to the first phase angle set, the control system performance under this set can be obtained, the second phase angle set can obtain the control system performance under this set, and the third phase angle set can obtain the control system performance under this set. system performance.

To sum up, the present invention can simplify the selection of the system, reduce the operation time, and has certain feasibility.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the principle block diagram of the direct torque control variable angle predictive control of permanent magnet synchronous motor based on the present invention;

Fig. 2 is the principle block diagram of the present invention;

Fig. 3 is the change diagram of stator flux linkage in the present invention;

Fig. 4 is a voltage vector selection diagram;

Fig. 5 is the torque ripple diagram of angle selection 1;

Fig. 6 is the stator flux linkage pulsation diagram of angle selection 1;

Fig. 7 is the selection voltage vector angle diagram of angle selection 1;

Fig. 8 is the torque ripple diagram of angle selection 2;

Fig. 9 is the stator flux linkage pulsation diagram of angle selection 2;

Fig. 10 is the selection voltage vector angle diagram of angle selection 2;

Fig. 11 is the torque ripple diagram of angle selection 3;

Fig. 12 is the stator flux linkage pulsation diagram of angle selection 3;

FIG. 13 is a selection voltage vector angle diagram for angle selection 3. FIG.

Detailed ways

Referring to FIG. 1, the present invention provides a voltage vector region selection method based on variable angle predictive control, including the following steps:

S1. Based on DTC predictive control, the voltage vector selection area is determined through the stator flux comparator and the torque comparator;

The basic selection area of variable angle predictive control of surface PMSM direct torque control is given. In the stator flux linkage coordinate system, the voltage vector selection range of surface PMSM direct torque control system is as follows:

∠V ₁₁ ∈(0°,90°)

∠V ₀₁ ∈(90°,180°-δ)

∠V ₀₀ ∈(180°,270°)

∠V ₁₀ ∈(270°,360°-δ)

Among them, ∠V ₁₁ is to increase the torque and increase the interval of the stator flux linkage, ∠V ₀₁ is to increase the torque and decrease the interval of the stator flux linkage, ∠V ₀₀ is to decrease the torque and decrease the stator flux linkage The interval of ∠V ₁₀ is the interval of reducing the torque and increasing the stator flux linkage, and δ is the torque angle.

S2. Divide the voltage vector phase angle selection area into equal parts, and calculate the objective function g value through the stator flux linkage amplitude and torque value.

Referring to Figure 2, first find the voltage vector Through the output value of the stator flux hysteresis comparator The output value τ and torque angle δ value of the torque hysteresis comparator select which interval the voltage vector is in, divide the voltage vector phase angle interval into four, and then input the stator flux linkage amplitude and torque value into the objective function Select min(g) from g, and find the voltage vector of the corresponding angle.

Please refer to Figure 3, the angle α is the selected phase angle of the voltage vector, α is divided into four regions, and each region is divided into three equal parts, and the four regions of the voltage vector phase angle are divided as shown in Figure 4.

In the given basic selection area of voltage vector, the voltage vector of predictive control is to select the optimal voltage vector from the limited set of alternative voltage vectors. The calculation amount and performance of predictive control are proportional to the fraction of the phase angle of the alternative voltage vector. When the fraction of the alternative voltage vector phase angle increases to a certain value, the performance improvement appears saturated. Specific steps are as follows:

S201, determine that the selected voltage vector amplitude is U _dc is the bus voltage. On the premise that the phase angle of the alternative voltage vector is divided into three equal parts, the first phase angle set is selected first, that is, the angle selection is 1

in, For the first phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the first phase angle set, increase the torque and reduce the alternative angle of the stator flux linkage, For the first phase angle set, reduce the torque and reduce the alternative angle of the stator flux linkage, For the first phase angle set, reduce the torque and reduce the alternative angle of the stator flux linkage, δ is the torque angle.

This phase angle set is the standard set of variable angle predictive control for surface PMSM direct torque control. Calculate the minimum value min(g) of the evaluation index g through torque ripple and stator flux ripple, and compare the g value, torque ripple and stator flux ripple.

The calculation formula of stator flux linkage is shown in (1)

The torque formula is shown in (2), (3), (4)

Define q as follows:

in, is the stator flux linkage amplitude at the next moment, is the voltage vector at the current moment, is the stator flux linkage amplitude at the current moment, δ(k+1) is the torque angle at the next moment, δ(k) is the torque angle at the current moment, and T _e (k+1) is the torque angle at the next moment. moment value.

The evaluation index function formula is shown in formula (5):

The torque ripple root mean square error is shown in formula (6), where n is the number of samples:

The root mean square error of flux linkage is shown in formula (7), where n is the number of samples:

Among them, n is the number of samples; T _e is the reference torque value, and ψ _s is the reference stator flux linkage amplitude.

Table 1 Control performance

Torque Ripple RMS Error/N.m 1.3519 Flux Fluctuation RMS Error/Wb 0.0065

S202, on the premise that the phase angle of the alternative voltage vector is divided into three equal parts, select the second phase angle set, that is: angle selection 2

in, For the second phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the second phase angle set, increase the torque and reduce the alternative angle of the stator flux linkage, For the second phase angle set, reduce the torque and reduce the alternative angle of the stator flux linkage, For the second phase angle set, reduce the torque and increase the alternative angle of the stator flux linkage, δ is the torque angle.

This phase angle set is a test set of variable angle predictive control of surface PMSM direct torque control. Calculate the minimum value min(g) of the evaluation index g through torque ripple and stator flux ripple, and compare the g value, torque ripple and stator flux ripple. The formula used is the same as for angle selection 1.

Table 2 Control performance

Torque Ripple RMS Error/N.m 1.3560 Flux Fluctuation RMS Error/Wb 0.0067

S203, on the premise of trisecting the phase angle of the alternative voltage vector, select the third phase angle set, that is: angle selection 3

in, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, For the third phase angle set, increase the torque and increase the alternative angle of the stator flux linkage, δ is the torque angle. This phase angle set is a test set of variable angle predictive control of surface PMSM direct torque control. Calculate the minimum value min(g) of the evaluation index g through torque ripple and stator flux ripple, and compare the g value, torque ripple and stator flux ripple; the formula used is the same as the angle selection 1 .

Table 3 Control performance

Torque Ripple RMS Error/N.m 1.3214 Flux Fluctuation RMS Error/Wb 0.0065

S3. Compare the g value, torque ripple and stator flux ripple of the three phase angle sets obtained in step S2, and analyze the selection of the alternative voltage vector phase angle for the direct torque control variable angle prediction of the surface permanent magnet synchronous motor .

Select the voltage vector magnitude:

Select the voltage vector angle:

It is determined that the system control effect of angle selection 3 is the best.

In order to make the purposes, 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 These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to Fig. 5, Fig. 6, Fig. 8, Fig. 9, Fig. 11, Fig. 12, it can be seen that in the case of three angle selections, the changes of torque ripple and stator flux ripple are not particularly large. Referring to Figure 7, Figure 10, and Figure 13, under three different angle selections, the angle selected by the control system will vary greatly, and the number of angles selected by the system will also vary greatly.

Different angle selections have little effect on the RMS error of flux linkage, but have a great influence on the RMS error of torque ripple.

Compared with angle selection 1, angle selection 3 is easy to implement and does not require torque angle information, but predictive control requires torque angle information.

The angle selection 3 simulation found:

When the torque is large, it is less likely to increase the torque and reduce the flux linkage (ie V ₀₁ ).

When the torque is large, V ₀₁ actually only selects 95 degrees and 135 degrees, that is, 175 degrees participates in the calculation, but there is no actual choice. The present invention considers the control idea of the variable candidate set: if the torque is small, three alternative variables are designed; if the torque is large, two alternative variables are designed, thereby reducing the operation time.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention all fall within the scope of the claims of the present invention. within the scope of protection.

Claims (9)

1. A voltage vector area selection method based on variable angle predictive control is characterized in that firstly, based on DTC predictive control, a selection area of direct torque control variable angle predictive control of a surface permanent magnet synchronous motor is given; then trisecting the voltage vector phase angle selection area to obtain three phase angle sets, and calculating a target function g value through a stator flux linkage amplitude value and a torque value; and finally, comparing the three phase angle sets, analyzing the control performance of the direct torque control variable angle prediction control of the surface permanent magnet synchronous motor, and finishing voltage vector region selection.

2. The variable angle predictive control-based voltage vector region selection method according to claim 1, wherein the surface permanent magnet synchronous motor direct torque control system voltage vector selection region is as follows:

∠V₁₁∈(0°,90°)

∠V₀₁∈(90°,180°-δ)

∠V₀₀∈(180°,270°)

∠V₁₀∈(270°,360°-δ)

wherein, ∠ V₁₁Section for increasing stator flux linkage for increasing torque, ∠ V₀₁Section for increasing torque and reducing stator flux linkage, ∠ V₀₀Interval for reducing stator flux linkage for reducing torque, ∠ V₁₀To reduce the torque, the stator flux interval is increased, δ being the torque angle.

3. The method of claim 1, wherein the voltage vector is first determinedOutput value by stator flux linkage hysteresis comparatorAnd selecting the interval where the voltage vector is located according to the output value tau and the torque angle delta of the torque hysteresis comparator, inputting the stator flux linkage amplitude and the torque value into a target function g, selecting min (g), and finding out the voltage vector of the corresponding angle.

4. The method of claim 3, wherein the objective function g is calculated as follows:

root mean square error T of torque ripple_{rip_RMSE}The calculation is as follows:

flux linkage ripple root mean square error psi_{rip_RMSE}The calculation is as follows:

wherein n is the number of samples; t is_eFor reference torque value, #_sIs referred to as stator flux linkage amplitude.

5. The variable angle predictive control-based voltage vector region selection method of claim 4, wherein the stator flux linkage magnitude is calculated as follows:

the torque equation is calculated as follows:

wherein,is the next momentThe amplitude of the stator flux linkage of (a),is the voltage vector at the present moment in time,delta (k +1) is the torque angle at the next moment, delta (k) is the torque angle at the current moment, T_e(k +1) is a torque value at the next time.

6. The method of claim 3, wherein selecting the voltage vector magnitude is based on a selection of a voltage vector regionComprises the following steps:

wherein, U_dcIs the bus voltage.

7. The variable angle predictive control-based voltage vector region selection method of claim 1, wherein the first set of phase angles is:

wherein,for the first set of phase angles, the torque is increased, the alternative angle of the stator flux linkage is increased,for the first phase angle set, the torque is increased, and the alternative angle of the stator flux linkage is reduced，For the first set of phase angles, the torque is reduced, the alternative angle of the stator flux linkage is reduced,and reducing the torque and the alternative angle of the stator flux linkage under the first phase angle set, wherein delta is a torque angle.

8. The variable angle predictive control-based voltage vector region selection method of claim 1, wherein the second set of phase angles is:

wherein,for the second set of phase angles, the torque is increased, the alternative angle of the stator flux linkage is increased,for the second set of phase angles, increasing the torque, decreasing the alternative angle of the stator flux linkage,for the second set of phase angles, the torque is reduced, the alternative angle of the stator flux linkage is reduced,and in the second phase angle set, reducing the torque, increasing the alternative angle of the stator flux linkage, and enabling delta to be the torque angle.

9. The variable angle predictive control-based voltage vector region selection method of claim 1, wherein the third set of phase angles is:

wherein,increasing the torque and the alternative angle of the stator flux linkage for the third phase angle set,increasing the torque and the alternative angle of the stator flux linkage for the third phase angle set,increasing the torque and the alternative angle of the stator flux linkage for the third phase angle set,and increasing the torque and the alternative angle of the stator flux linkage under the third phase angle set, wherein delta is a torque angle.