阅读说明：本技术 电机的弱磁控制方法、弱磁控制装置和可读存储介质 (Weak magnetic control method and device for motor and readable storage medium ) 是由 赵健平 王彤 于 2020-12-01 设计创作，主要内容包括：本发明提出了一种电机的弱磁控制方法、电机的弱磁控制装置和可读存储介质。其中,电机的弱磁控制方法包括：获取电机的直轴指令电压、交轴指令电压和母线电压；基于母线电压的变化率大于第一阈值,调节母线电压,并根据母线电压、直轴指令电压和交轴指令电压,计算弱磁电流；根据弱磁电流对电机进行弱磁控制。通过本发明的技术方案,一方面,可以有效地解决母线电压过低时电机能量反灌驱动器,而导致的驱动器电压剧烈波动甚至过压失控的问题；另一方面,能够避免由于母线电压回冲而导致弱磁电流降低的问题,确保弱磁电流的准确性,进一步提高对电机的控制效果。(The invention provides a field weakening control method of a motor, a field weakening control device of the motor and a readable storage medium. The field weakening control method of the motor comprises the following steps: acquiring direct axis command voltage, quadrature axis command voltage and bus voltage of the motor; based on the fact that the change rate of the bus voltage is larger than a first threshold value, the bus voltage is adjusted, and weak magnetic current is calculated according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage; and carrying out flux weakening control on the motor according to the flux weakening current. Through the technical scheme of the invention, on one hand, the problem that the voltage of the driver fluctuates violently and even the overvoltage is out of control caused by the fact that the energy of the motor reversely flows into the driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to the voltage backlash of the bus can be avoided, the accuracy of the weak magnetic current is ensured, and the control effect on the motor is further improved.)

1. A field weakening control method of a motor is characterized by comprising the following steps:

acquiring direct axis command voltage, quadrature axis command voltage and bus voltage of the motor;

based on the fact that the change rate of the bus voltage is larger than a first threshold value, the bus voltage is adjusted, and the weak magnetic current is calculated according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage;

and carrying out flux weakening control on the motor according to the flux weakening current.

2. The field weakening control method of the motor according to claim 1, wherein the adjusting the bus voltage and calculating the field weakening current of the motor according to the bus voltage, the direct axis command voltage and the quadrature axis command voltage specifically comprises:

reducing the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage;

and calculating the weak magnetic current according to the reduced average value, the direct axis instruction voltage and the quadrature axis instruction voltage.

3. The field weakening control method of the motor according to claim 2, wherein the reducing of the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage specifically comprises:

subtracting a first preset voltage value from the minimum value of the bus voltage to obtain an updated minimum value of the bus voltage;

and calculating the average value of the maximum value of the alternating voltage and the updated minimum value of the bus voltage.

4. The field weakening control method of an electric motor according to claim 3, further comprising:

and acquiring the first preset voltage value according to the change rate of the bus voltage.

5. The field weakening control method of the motor according to claim 2, wherein the reducing of the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage specifically comprises:

calculating an average value of the maximum value of the alternating voltage and the minimum value of the bus voltage;

and subtracting a second preset voltage value from the average value.

6. The field weakening control method of an electric motor according to claim 5, further comprising:

and acquiring the second preset voltage value according to the change rate of the bus voltage.

7. The field weakening control method of an electric motor according to any one of claims 2 to 6,

the first threshold value includes a preset value or a rate of change of the alternating voltage.

8. The field weakening control method of an electric motor according to any one of claims 2 to 6, further comprising:

acquiring the phase of the alternating voltage;

and calculating the change rate of the bus voltage and the change rate of the alternating voltage based on the condition that the phase of the alternating voltage meets a preset phase range.

9. The field weakening control method of an electric motor according to any one of claims 2 to 6, further comprising:

and taking the maximum value of the alternating-current voltage as the minimum value of the bus voltage based on the fact that the minimum value of the bus voltage is larger than the maximum value of the alternating-current voltage.

10. The field weakening control method of the motor according to any one of claims 2 to 6, wherein the calculating the field weakening current according to the reduced average value, the direct axis command voltage and the quadrature axis command voltage specifically comprises:

obtaining the product of the average value and a preset coefficient;

and calculating the weak magnetic current according to the product, the direct axis instruction voltage and the quadrature axis instruction voltage.

11. The field weakening control method for the motor according to any one of claims 1 to 6, wherein the step of determining that the change rate based on the bus voltage is greater than a first threshold specifically comprises:

a difference between the rate of change based on the bus voltage and the first threshold is greater than a second threshold.

12. The field weakening control method of the motor according to any one of claims 2 to 6, further comprising, after acquiring the direct axis command voltage, the quadrature axis command voltage and the bus bar voltage of the motor:

and calculating the weak magnetic current according to the average value of the maximum value of the alternating current voltage and the minimum value of the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage on the basis that the change rate of the bus voltage is smaller than or equal to the first threshold.

13. A field weakening control device of a motor is characterized by comprising:

a memory storing programs or instructions;

a processor which, when executing the program or instructions, implements a field weakening control method for an electrical machine as claimed in any one of claims 1 to 12.

14. The field weakening control apparatus of an electric motor according to claim 13, further comprising:

and the current acquisition device is used for acquiring alternating voltage and bus voltage.

15. A readable storage medium on which a program or instructions are stored, characterized in that the program or instructions, when executed by a processor, implement a field weakening control method of an electric machine according to any one of claims 1 to 12.

Technical Field

The invention relates to the technical field of motor control, in particular to a field weakening control method of a motor, a field weakening control device of the motor and a readable storage medium.

Background

Because the electrolytic capacitor has the problems of service life, reliability, cost and the like, the thin-film capacitor with small capacitance value is used for replacing the electrolytic capacitor with large capacitance value, namely, a control mode without the electrolytic capacitor is adopted. After the electrolytic capacitor-free control mode is adopted, the bus voltage is 2 times of the network side voltage frequency fluctuation and even drops to the vicinity of zero, the fluctuating bus voltage needs weak magnetic control, but even if weak magnetic control is adopted, the problem of poor current control still exists when the bus voltage is too low, under certain working conditions, even if the motor energy is reversely filled into a driver, the bus voltage is back flushed, and as shown in figure 1, the bus voltage is back flushed relative to the alternating current voltage.

The weak magnetic control in the related technology adopts real-time bus voltage and the average value thereof as feedback voltage of the weak magnetic control, bus voltage backlash can occur when weak magnetic current is not large enough, real-time bus voltage and the average value thereof can be raised by the bus voltage of the backlash, the weak magnetic current is further reduced, the voltage insufficiency is aggravated, current is out of control, the bus voltage is further backlash, and even fault shutdown is generated.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art or the related art.

To this end, an aspect of the present invention is to provide a field weakening control method of a motor.

Another aspect of the invention is to provide a field weakening control device for an electric machine.

Yet another aspect of the present invention is directed to a readable storage medium.

In view of the above, according to an aspect of the present invention, there is provided a field weakening control method for a motor, including: acquiring direct axis command voltage, quadrature axis command voltage and bus voltage of the motor; based on the fact that the change rate of the bus voltage is larger than a first threshold value, the bus voltage is adjusted, and the weak magnetic current of the motor is calculated according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage; and carrying out flux weakening control on the motor according to the flux weakening current.

In the technical scheme, the bus voltage is obtained, whether the change rate of the bus voltage is greater than a first threshold value or not is judged, and when the change rate of the bus voltage is greater than the first threshold value, the phenomenon of bus voltage backlash is indicated, so that the bus voltage is adjusted under the condition. And then after the regulation, calculating the flux weakening current according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage so as to realize flux weakening control on the motor. In the technical scheme of the invention, the problem of bus voltage backlash is determined by judging the change rate of the bus voltage, and further, the bus voltage is adjusted according to the problem. On one hand, the problem that the voltage of the driver fluctuates violently and even the overvoltage is out of control caused by the fact that the energy of the motor reversely flows into the driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to the voltage backlash of the bus can be avoided, the accuracy of the weak magnetic current is ensured, and the control effect on the motor is further improved.

The field weakening control method of the motor according to the present invention may further have the following technical features:

in any of the above technical solutions, adjusting the bus voltage, and calculating the field weakening current of the motor according to the bus voltage, the direct axis command voltage, and the quadrature axis command voltage specifically includes: reducing the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage; and calculating the weak magnetic current according to the reduced average value, the direct axis command voltage and the quadrature axis command voltage.

In the technical scheme, the alternating current voltage of the motor is obtained, the average value of the maximum value of the alternating current voltage and the minimum value of the bus voltage is controlled to be reduced, and further the flux weakening current is calculated according to the reduced average value, the direct axis command voltage and the quadrature axis command voltage. In the technical scheme, on one hand, by means of an adjusting mode of reducing the average value, the weak magnetic current can be increased under the condition that the bus voltage is backflushed, the current is out of control and the bus voltage is further backflushed due to insufficient aggravated voltage, and the fault shutdown is avoided; on the other hand, the problem that the weak magnetic current is larger due to lower available voltage caused by only utilizing the minimum value of the bus voltage to determine the weak magnetic current is solved.

It should be noted that, in the technical solution of the present invention, the minimum value of the bus voltage is used instead of the maximum value of the bus voltage for adjustment, so that the problem of runaway motor control caused by overvoltage can be avoided.

In any of the above technical solutions, reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage specifically includes: subtracting the first preset voltage value from the minimum value of the bus voltage to obtain the updated minimum value of the bus voltage; and calculating the average value of the maximum value of the alternating voltage and the updated minimum value of the bus voltage.

In this technical solution, one method of reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage is: the minimum value of the bus voltage is first updated by subtracting a preset voltage value from the minimum value of the bus voltage, and then the average value of the updated minimum value of the bus voltage and the maximum value of the alternating-current voltage is calculated. The average value is reduced through the mode, so that the problem of bus voltage backlash is solved, and the situations that weak magnetic current is reduced and insufficient voltage is aggravated due to the bus voltage backlash are avoided.

In any of the above technical solutions, the field weakening control method for the motor further includes: and acquiring a first preset voltage value according to the change rate of the bus voltage.

In the technical scheme, a first preset voltage value is determined according to the change rate of the bus voltage, namely, the degree of reduction of the average value is determined according to the specific condition of the bus voltage backlash, so that the backlash of the bus voltage is compensated through the reduction of the average value, and on one hand, the problem that the energy of a motor reversely flows into a driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to bus voltage backlash can be avoided, and the accuracy of the weak magnetic current is ensured.

In any of the above technical solutions, reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage specifically includes: calculating the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage; the average value is subtracted by a second preset voltage value.

In this technical solution, one method of reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage is: the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage is first calculated, and then a preset voltage value is subtracted from the average value to update the average value. The average value is reduced through the mode, so that the problem of bus voltage backlash is solved, and the situations that weak magnetic current is reduced and insufficient voltage is aggravated due to the bus voltage backlash are avoided.

In any of the above technical solutions, the field weakening control method for the motor further includes: and acquiring a second preset voltage value according to the change rate of the bus voltage.

In the technical scheme, a second preset voltage value is determined according to the change rate of the bus voltage, namely, the degree of reduction of the average value is determined according to the specific condition of the bus voltage backlash, so that the backlash of the bus voltage is compensated through the reduction of the average value, and on one hand, the problem that the energy of the motor reversely flows into the driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to bus voltage backlash can be avoided, and the accuracy of the weak magnetic current is ensured.

In any of the above solutions, the first threshold includes a preset value or a rate of change of an ac voltage.

In the technical scheme, the change rate of the bus voltage is compared with the change rate of the alternating-current voltage to judge whether the problem of bus voltage backlash occurs or not. Because the bus voltage can follow the alternating current voltage under the condition that the bus voltage backlash does not occur, and when the change rate of the bus voltage is larger than that of the alternating current voltage, the bus voltage backlash phenomenon is indicated.

In addition, because the power grid is relatively stable and the alternating voltage change rate is basically fixed, the alternating voltage change rate and the bus voltage change rate can be compared with a preset value directly without being limited to comparison.

By the mode, the problem of bus voltage backlash can be accurately judged, and then measures for adjusting the bus voltage can be taken to ensure the accuracy of weak magnetic current, so that the control effect on the motor can be improved.

In any of the above technical solutions, the field weakening control method for the motor further includes: acquiring the phase of the alternating voltage; and calculating the change rate of the bus voltage and the change rate of the alternating voltage based on the fact that the phase of the alternating voltage meets a preset phase range.

In the technical scheme, because the change rate of the previous voltage of the valley voltage is a negative value, and the change rate of the next voltage of the valley voltage is a positive value, the difference between the two change rates is large, so if the change rates of the alternating voltage and the bus voltage near the valley voltage are utilized, the change rates are inaccurate and easy to make mistakes, the change rate of the alternating voltage is not calculated near the valley voltage of the alternating voltage, and the change rate of the bus voltage is not calculated near the valley voltage of the bus voltage. Specifically, the valley voltage is determined through the phase of the alternating voltage, and in the technical scheme of the invention, when the phase of the alternating voltage meets a preset phase range, the change rate of the bus voltage and the change rate of the alternating voltage are calculated, so that the accuracy of the change rate of the bus voltage and the change rate of the alternating voltage is ensured, and the accuracy of the judgment of the bus voltage backlash is further ensured.

The predetermined phase range is a phase range that does not correspond to the vicinity of the valley of the ac voltage, that is, the rate of change is not calculated in the phase range corresponding to the vicinity of the valley of the ac voltage, and the rate of change is calculated in the phase range other than the phase range corresponding to the vicinity of the valley of the ac voltage.

In any of the above technical solutions, the field weakening control method for the motor further includes: and taking the maximum value of the alternating-current voltage as the minimum value of the bus voltage based on the fact that the minimum value of the bus voltage is larger than the maximum value of the alternating-current voltage.

In the technical scheme, the minimum value of the bus voltage is limited not to be larger than the maximum value of the alternating voltage, if the minimum value of the bus voltage is larger than the maximum value of the alternating voltage, the minimum value of the bus voltage is made to be the maximum value of the alternating voltage, the minimum value of the bus voltage is limited, and the problem that the motor control is out of control due to overvoltage can be avoided.

In any of the above technical solutions, calculating the field weakening current according to the reduced average value, the direct axis command voltage, and the quadrature axis command voltage specifically includes: obtaining the product of the average value and a preset coefficient; and calculating the flux weakening current according to the product, the direct axis command voltage and the quadrature axis command voltage.

In the technical scheme, the average value can be obtained by averaging the maximum value of the alternating voltage and the minimum value of the bus voltage, and can also be multiplied by a preset coefficient on the basis of averaging, wherein the preset coefficient is larger than 1, and compared with the average value, the voltage can be increased, so that the efficiency of the motor can be improved.

In any of the above technical solutions, the method specifically includes, based on the bus voltage change rate being greater than the first threshold: the difference between the rate of change based on the bus voltage and the first threshold is greater than a second threshold.

In the technical scheme, the change rate of the bus voltage is compared with the first threshold value, and if the change rate of the bus voltage is found to be obviously greater than the first threshold value, the problem of bus voltage backlash can be definitely judged, so that the occurrence of the condition of misjudgment is avoided.

In any one of the above technical solutions, after obtaining the direct axis command voltage, the quadrature axis command voltage, and the bus voltage of the motor, the method further includes: and calculating the weak magnetic current according to the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage, the direct-axis command voltage and the quadrature-axis command voltage on the basis that the change rate of the bus voltage is smaller than or equal to a first threshold value.

In the technical scheme, when the change rate of the bus voltage is judged to be less than or equal to the first threshold, the bus voltage is indicated to have no phenomenon of bus voltage backlash, in this case, the bus voltage is not required to be adjusted, the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage is directly calculated, and further, the weak magnetic current is calculated according to the average value of the direct axis command voltage and the quadrature axis command voltage. Through the mode, the flux weakening current is determined by combining the maximum value of the alternating voltage, and the motor efficiency can be improved.

According to another aspect of the present invention, there is provided a field-weakening control apparatus of a motor, including: a memory storing programs or instructions; and when the processor executes the program or the instructions, the field weakening control method of the motor in any technical scheme is realized.

In the technical scheme, the bus voltage is obtained, whether the change rate of the bus voltage is greater than a first threshold value or not is judged, and when the change rate of the bus voltage is greater than the first threshold value, the phenomenon of bus voltage backlash is indicated, so that the bus voltage is adjusted under the condition. And then after the regulation, calculating the flux weakening current according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage so as to realize flux weakening control on the motor. In the technical scheme of the invention, the problem of bus voltage backlash is determined by judging the change rate of the bus voltage, and further, the bus voltage is adjusted according to the problem. On one hand, the problem that the voltage of the driver fluctuates violently and even the overvoltage is out of control caused by the fact that the energy of the motor reversely flows into the driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to the voltage backlash of the bus can be avoided, the accuracy of the weak magnetic current is ensured, and the control effect on the motor is further improved.

The field weakening control device of the motor according to the present invention may further include the following features:

in the above technical solution, the field weakening control device of the motor further includes: and the current acquisition device is used for acquiring alternating voltage and bus voltage.

According to the technical scheme, the alternating current voltage and the bus voltage are collected by the current collecting device, the average value of the maximum value of the alternating current voltage and the average value of the minimum value of the bus voltage is controlled to be reduced when the bus voltage backlash phenomenon occurs, and then the flux weakening current is calculated according to the reduced average value, the direct axis instruction voltage and the quadrature axis instruction voltage, so that flux weakening control over the motor is achieved. In the technical scheme, on one hand, by means of an adjusting mode of reducing the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage, the weak magnetic current can be increased under the condition that the bus voltage is backflushed, the phenomenon that the current is out of control and the bus voltage is further backflushed due to insufficient aggravated voltage is avoided, and the fault shutdown is avoided; on the other hand, the problem that the weak magnetic current is larger due to lower available voltage caused by only utilizing the minimum value of the bus voltage to determine the weak magnetic current is solved.

According to a further aspect of the present invention, there is provided a readable storage medium, on which a program or instructions are stored, which when executed by a processor, implement the field weakening control method of the motor according to any one of the above-mentioned technical solutions.

The readable storage medium, the program or the instructions provided by the present invention, when executed by the processor, implement the steps of the field weakening control method for the motor according to any one of the above technical solutions, and therefore the readable storage medium includes all the beneficial effects of the field weakening control method for the motor according to any one of the above technical solutions.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a waveform diagram showing an ac voltage and a bus voltage in the related art;

fig. 2 is a flow chart showing a field weakening control method of the motor of the first embodiment of the present invention;

fig. 3 is a schematic view showing a control process of field weakening control of the motor of the embodiment of the present invention;

fig. 4 is a flow chart showing a field weakening control method of a motor according to a second embodiment of the present invention;

fig. 5 is a flowchart illustrating a field weakening control method of a motor according to a third embodiment of the present invention;

fig. 6 is a flowchart illustrating a field weakening control method of a motor according to a fourth embodiment of the present invention;

fig. 7 is a flow chart showing a field weakening control method suitable for a small-capacitance motor system according to a fifth embodiment of the present invention;

fig. 8 shows a schematic block diagram of a field weakening control apparatus of a motor of an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

The embodiment of the first aspect of the present invention provides a field weakening control method for a motor, and the field weakening control method for the motor is described in detail through the first embodiment to the fifth embodiment.

First embodiment, fig. 2 is a flowchart illustrating a field weakening control method of a motor according to a first embodiment of the present invention. The field weakening control method of the motor comprises the following steps:

step 202, acquiring direct axis instruction voltage, quadrature axis instruction voltage and bus voltage of a motor;

step 204, based on the fact that the change rate of the bus voltage is larger than a first threshold value, adjusting the bus voltage, and calculating the weak magnetic current of the motor according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage;

and step 206, carrying out flux weakening control on the motor according to the flux weakening current.

In the technical scheme, the bus voltage is obtained, whether the change rate of the bus voltage is greater than a first threshold value or not is judged, and when the change rate of the bus voltage is greater than the first threshold value, the phenomenon of bus voltage backlash is indicated, so that the bus voltage is adjusted under the condition. And then after the regulation, calculating the flux weakening current according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage so as to realize flux weakening control on the motor. In the technical scheme of the invention, the problem of bus voltage backlash is determined by judging the change rate of the bus voltage, and further, the bus voltage is adjusted according to the problem. On one hand, the problem that the voltage of the driver fluctuates violently and even the overvoltage is out of control caused by the fact that the energy of the motor reversely flows into the driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to the voltage backlash of the bus can be avoided, the accuracy of the weak magnetic current is ensured, and the control effect on the motor is further improved.

It is worth noting that since the bus voltage decrease change rate has no influence on the control system, mainly the increase rate is too fast, that is, the motor energy back-flow driver causes the traditional flux weakening runaway, the bus voltage increase change rate needs to be compared with the first threshold.

In one embodiment, as shown in FIG. 3, the bus voltage V is applied_dcAs feedback voltage for field weakening control, combined with direct-axis command voltage u_dAnd quadrature axis command voltage u_qAfter PI (Proportional Integral) control, weak magnetic current i is obtained_drefAnd further based on the weak magnetic current i_drefAnd carrying out field weakening control on the motor. In FIG. 3, the description is given3 are all coefficients, can be based on

The actual situation is selected.

In the above technical solution, the first threshold includes a preset value or a rate of change of the ac voltage.

In the technical scheme, the change rate of the bus voltage is compared with the change rate of the alternating-current voltage to judge whether the problem of bus voltage backlash occurs or not. Because the bus voltage can follow the alternating current voltage under the condition that the bus voltage backlash does not occur, and when the change rate of the bus voltage is larger than that of the alternating current voltage, the bus voltage backlash phenomenon is indicated.

In addition, because the power grid is relatively stable and the alternating voltage change rate is basically fixed, the alternating voltage change rate and the bus voltage change rate can be compared with a preset value directly without being limited to comparison.

By the mode, the problem of bus voltage backlash can be accurately judged, and then measures for adjusting the bus voltage can be taken to ensure the accuracy of weak magnetic current, so that the control effect on the motor can be improved.

In any of the above technical solutions, the method specifically includes, based on the bus voltage change rate being greater than the first threshold: the difference between the rate of change based on the bus voltage and the first threshold is greater than a second threshold.

In the technical scheme, the change rate of the bus voltage is compared with the first threshold value, and if the change rate of the bus voltage is found to be obviously greater than the first threshold value, the problem of bus voltage backlash can be definitely judged, so that the occurrence of the condition of misjudgment is avoided.

Second embodiment, fig. 4 is a flowchart illustrating a field weakening control method of a motor according to a second embodiment of the present invention. The field weakening control method of the motor comprises the following steps:

step 402, acquiring direct-axis instruction voltage, quadrature-axis instruction voltage, alternating-current voltage and bus voltage of a motor;

step 404, based on the fact that the change rate of the bus voltage is larger than a first threshold value, reducing the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage;

step 406, calculating a flux weakening current according to the reduced average value, the direct axis instruction voltage and the quadrature axis instruction voltage;

and 408, carrying out flux weakening control on the motor according to the flux weakening current.

In the technical scheme, alternating current voltage of the motor is obtained, the average value of the maximum value of the alternating current voltage and the minimum value of the bus voltage is controlled to be reduced, and further, direct axis instruction voltage, quadrature axis instruction voltage and the reduced average value are sent to a flux weakening control link to generate flux weakening current. In the technical scheme, on one hand, by means of an adjusting mode of reducing the average value, the weak magnetic current can be increased under the condition that the bus voltage is backflushed, the current is out of control and the bus voltage is further backflushed due to insufficient aggravated voltage, and the fault shutdown is avoided; on the other hand, the problem that the weak magnetic current is larger due to lower available voltage caused by only utilizing the minimum value of the bus voltage to determine the weak magnetic current is solved.

Note that the maximum value of the ac voltage and the minimum value of the bus voltage are the maximum value of the ac voltage and the minimum value of the bus voltage, respectively, which are obtained in 1/2 ac voltage cycles.

It should be noted that, in the technical solution of the present invention, the minimum value of the bus voltage is used instead of the maximum value of the bus voltage for adjustment, so that the problem of runaway motor control caused by overvoltage can be avoided.

In the above technical solution, reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage specifically includes: subtracting the first preset voltage value from the minimum value of the bus voltage to obtain the updated minimum value of the bus voltage; and calculating the average value of the maximum value of the alternating voltage and the updated minimum value of the bus voltage.

In this technical solution, one method of reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage is: the minimum value of the bus voltage is first updated by subtracting a preset voltage value from the minimum value of the bus voltage, and then the average value of the updated minimum value of the bus voltage and the maximum value of the alternating-current voltage is calculated. The average value is reduced through the mode, so that the problem of bus voltage backlash is solved, and the situations that weak magnetic current is reduced and insufficient voltage is aggravated due to the bus voltage backlash are avoided.

In the above technical solution, the field weakening control method of the motor further includes: and acquiring a first preset voltage value according to the change rate of the bus voltage.

In the technical scheme, a first preset voltage value is determined according to the change rate of the bus voltage, namely, the degree of reduction of the average value is determined according to the specific condition of the bus voltage backlash, so that the backlash of the bus voltage is compensated through the reduction of the average value, and on one hand, the problem that the energy of a motor reversely flows into a driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to bus voltage backlash can be avoided, and the accuracy of the weak magnetic current is ensured.

The relationship between the change rate of the bus voltage and the first preset voltage value is not limited to a relationship such as a ratio, an exponential, and a quadratic function.

In the above technical solution, reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage specifically includes: calculating the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage; the average value is subtracted by a second preset voltage value.

In this technical solution, one method of reducing the average value of the maximum value of the ac voltage and the minimum value of the bus voltage is: the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage is first calculated, and then a preset voltage value is subtracted from the average value to update the average value. The average value is reduced through the mode, so that the problem of bus voltage backlash is solved, and the situations that weak magnetic current is reduced and insufficient voltage is aggravated due to the bus voltage backlash are avoided.

In the above technical solution, the field weakening control method of the motor further includes: and acquiring a second preset voltage value according to the change rate of the bus voltage.

In the technical scheme, a second preset voltage value is determined according to the change rate of the bus voltage, namely, the degree of reduction of the average value is determined according to the specific condition of the bus voltage backlash, so that the backlash of the bus voltage is compensated through the reduction of the average value, and on one hand, the problem that the energy of the motor reversely flows into the driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to bus voltage backlash can be avoided, and the accuracy of the weak magnetic current is ensured.

It should be noted that the relationship between the change rate of the bus voltage and the second preset voltage value is not limited to a proportional, exponential, quadratic function, and the like.

In any of the above technical solutions, the field weakening control method for the motor further includes: and taking the maximum value of the alternating-current voltage as the minimum value of the bus voltage based on the fact that the minimum value of the bus voltage is larger than the maximum value of the alternating-current voltage.

In the technical scheme, the minimum value of the bus voltage is limited not to be larger than the maximum value of the alternating voltage, if the minimum value of the bus voltage is larger than the maximum value of the alternating voltage, the minimum value of the bus voltage is made to be the maximum value of the alternating voltage, the minimum value of the bus voltage is limited, and the problem that the motor control is out of control due to overvoltage can be avoided.

In any of the above technical solutions, calculating the field weakening current according to the reduced average value, the direct axis command voltage, and the quadrature axis command voltage specifically includes: obtaining the product of the average value and a preset coefficient; and calculating the flux weakening current according to the product, the direct axis command voltage and the quadrature axis command voltage.

In the technical scheme, the average value can be obtained by averaging the maximum value of the alternating voltage and the minimum value of the bus voltage, and can also be multiplied by a preset coefficient on the basis of averaging, wherein the preset coefficient is larger than 1, and compared with the average value, the voltage can be increased, so that the efficiency of the motor can be improved.

Third embodiment, fig. 5 is a flowchart illustrating a field weakening control method for a motor according to a third embodiment of the present invention. The field weakening control method of the motor comprises the following steps:

502, acquiring direct-axis instruction voltage, quadrature-axis instruction voltage, alternating current voltage and bus voltage of a motor;

step 504, calculating the change rate of the bus voltage and the change rate of the alternating voltage based on the phase of the alternating voltage meeting a preset phase range;

step 506, based on the fact that the change rate of the bus voltage is larger than that of the alternating current voltage, reducing the average value of the maximum value of the alternating current voltage and the minimum value of the bus voltage;

step 508, calculating the flux weakening current according to the reduced average value, the direct axis command voltage and the quadrature axis command voltage;

and 510, carrying out flux weakening control on the motor according to the flux weakening current.

In the technical scheme, because the change rate of the previous voltage of the valley voltage is a negative value, and the change rate of the next voltage of the valley voltage is a positive value, the difference between the two change rates is large, so if the change rates of the alternating voltage and the bus voltage near the valley voltage are utilized, the change rates are inaccurate and easy to make mistakes, the change rate of the alternating voltage is not calculated near the valley voltage of the alternating voltage, and the change rate of the bus voltage is not calculated near the valley voltage of the bus voltage. Specifically, the valley voltage is determined through the phase of the alternating voltage, and in the technical scheme of the invention, when the phase of the alternating voltage meets a preset phase range, the change rate of the bus voltage and the change rate of the alternating voltage are calculated, so that the accuracy of the change rate of the bus voltage and the change rate of the alternating voltage is ensured, and the accuracy of the judgment of the bus voltage backlash is further ensured.

The predetermined phase range is a phase range that does not correspond to the vicinity of the valley of the ac voltage, that is, the rate of change is not calculated in the phase range corresponding to the vicinity of the valley of the ac voltage, and the rate of change is calculated in the phase range other than the phase range corresponding to the vicinity of the valley of the ac voltage. For example, when the phase of the ac voltage is 50 degrees, it may be considered as corresponding to the valley voltage of the ac voltage, and then it may be set that the rate of change is not calculated between 45 degrees and 55 degrees.

The vicinity of the voltage trough is [ trough voltage-preset voltage, trough voltage + preset voltage ], and the preset voltage is related to parameters such as motor hardware and the like.

In addition, the phase of the alternating voltage is obtained by phase locking of the alternating voltage.

Fourth embodiment, fig. 6 is a flowchart illustrating a field weakening control method for a motor according to a fourth embodiment of the present invention. The field weakening control method of the motor comprises the following steps:

step 602, acquiring direct axis instruction voltage, quadrature axis instruction voltage, alternating current voltage and bus voltage of a motor;

step 604, judging whether the change rate of the bus voltage is greater than a first threshold value, if so, entering step 606, otherwise, entering step 610;

step 606, reducing the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage;

step 608, calculating the flux weakening current according to the reduced average value, the direct axis command voltage and the quadrature axis command voltage;

step 610, calculating weak magnetic current according to the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage;

and step 612, carrying out flux weakening control on the motor according to the flux weakening current.

In the technical scheme, when the change rate of the bus voltage is judged to be less than or equal to the first threshold, the bus voltage is indicated to have no phenomenon of bus voltage backlash, in this case, the bus voltage is not required to be adjusted, the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage is directly calculated, and further, the weak magnetic current is calculated according to the average value of the direct axis command voltage and the quadrature axis command voltage. Through the mode, the flux weakening current is determined by combining the maximum value of the alternating voltage, and the motor efficiency can be improved.

In a fifth embodiment of the present invention, in consideration of an influence of a bus voltage backlash on field weakening, a field weakening control method suitable for a small capacitance motor system is provided, and fig. 7 shows a flow diagram of the field weakening control method suitable for the small capacitance motor system according to the fifth embodiment of the present invention. The field weakening control method comprises the following steps:

step 702, sampling an alternating voltage and a bus voltage, and respectively calculating the change rate of the alternating voltage and the change rate of the bus voltage;

step 704, acquiring the maximum value of the alternating voltage and the minimum value of the bus voltage;

step 706, judging whether the change rate of the bus voltage is obviously greater than that of the alternating voltage, if so, entering step 708, otherwise, entering step 712;

step 708, calculating a variable related to the change rate of the bus voltage;

step 710, subtracting the relevant variable from the minimum value of the bus voltage;

step 712, determining whether the average bus voltage updating period is reached, if yes, entering step 714, otherwise, returning to step 702;

step 714, updating the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage;

and step 716, performing weak magnetic calculation.

In this embodiment, the real-time ac voltage and the bus voltage are acquired, the rate of change of the ac voltage and the rate of change of the bus voltage are calculated, and the maximum value of the ac voltage and the minimum value of the bus voltage are obtained in 1/2 ac voltage cycles. Further, comparing the rate of change of the ac voltage with the rate of change of the bus voltage, and if the rate of change of the bus voltage increase is found to be significantly greater than the rate of change of the ac voltage increase, subtracting a dependent variable from the minimum value of the bus voltage, the dependent variable being related to the rate of change of the bus voltage increase; otherwise, the minimum value of the bus voltage remains unchanged. And calculating the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage, and sending the average value as the feedback voltage of the field weakening control to the field weakening link for calculation.

Further, the process of obtaining the change rate of the alternating voltage comprises: and taking an absolute value of the alternating voltage, subtracting the alternating voltage sampled at the last moment from the alternating voltage sampled at the current moment, and differentiating the sampling time by using the difference value to obtain the change rate of the alternating voltage.

The process for acquiring the change rate of the bus voltage comprises the following steps: and subtracting the bus voltage sampled at the last moment from the bus voltage sampled at the current moment, and differentiating the sampling time by using the difference value to obtain the change rate of the bus voltage.

In addition, the ac voltage and bus voltage do not calculate a rate of change near the valley voltage, which is otherwise prone to error. The valley voltage may be determined based on the alternating voltage phase, with a positive phase threshold and a negative phase threshold added based on the valley phase to avoid toggling of the rate of change. And, the alternating voltage phase can be obtained by alternating voltage phase locking.

Further, the minimum value of the bus voltage should not be greater than the maximum value of the alternating voltage, otherwise, the minimum value of the bus voltage is set as the maximum value of the alternating voltage, so as to avoid the overvoltage problem.

Further, since the bus voltage decrease change rate has no influence on the control system, mainly the increase rate is too fast, that is, the motor energy back-flow driver causes the conventional flux weakening runaway, the bus voltage increase change rate needs to be compared with the ac voltage increase change rate.

If the bus voltage increase change rate is obviously larger than the alternating voltage increase change rate, selecting a related variable according to the bus voltage increase change rate, and subtracting the related variable from the minimum value of the bus voltage to obtain a new minimum value of the bus voltage; if the bus voltage increase rate of change is less than the alternating voltage increase rate of change, the minimum value of the bus voltage remains constant.

The relationship between the bus voltage increase rate and the relevant variable is not limited to a relationship such as a ratio, an exponential function, a quadratic function, and the like.

Further, the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage can be obtained by averaging the maximum value of the alternating voltage and the minimum value of the bus voltage, and can also be multiplied by a coefficient k on the basis of the average value so as to improve the efficiency of the motor.

Further, since the grid is relatively stable and the rate of change of the ac voltage is substantially constant, the rate of change of the ac voltage may be compared with a variable without being limited to the rate of change of the ac voltage and the rate of change of the bus voltage.

The embodiment of the invention is mainly applied to the field of small-capacitance drive control, is simple to realize, can effectively solve the problem of severe fluctuation of the driver voltage and even over-voltage runaway caused by reverse flowing of motor energy into the driver when the bus voltage is too low, and improves the system stability.

In the embodiment of the second aspect of the present invention, a field weakening control device 800 for an electric motor is provided, and fig. 8 shows a schematic block diagram of the field weakening control device 800 for the electric motor according to the embodiment of the present invention. Wherein, the field weakening control device 800 of the motor comprises:

a memory 802 storing programs or instructions;

the processor 804, when the processor 804 executes the program or the instruction, implements the field weakening control method of the motor according to any one of the above technical solutions.

The memory 802 and the processor 804 may be connected by a bus or other means. The Processor 804 may include one or more Processing units, and the Processor 804 may be a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or the like.

In the technical scheme, the bus voltage is obtained, whether the change rate of the bus voltage is greater than a first threshold value or not is judged, and when the change rate of the bus voltage is greater than the first threshold value, the phenomenon of bus voltage backlash is indicated, so that the bus voltage is adjusted under the condition. And then after the regulation, calculating the flux weakening current according to the bus voltage, the direct axis instruction voltage and the quadrature axis instruction voltage so as to realize flux weakening control on the motor. In the technical scheme of the invention, the problem of bus voltage backlash is determined by judging the change rate of the bus voltage, and further, the bus voltage is adjusted according to the problem. On one hand, the problem that the voltage of the driver fluctuates violently and even the overvoltage is out of control caused by the fact that the energy of the motor reversely flows into the driver when the bus voltage is too low can be effectively solved; on the other hand, the problem that the weak magnetic current is reduced due to the voltage backlash of the bus can be avoided, the accuracy of the weak magnetic current is ensured, and the control effect on the motor is further improved.

In the above technical solution, the field weakening control apparatus 800 of the motor further includes:

and a current collecting device 806 for collecting the alternating voltage and the bus voltage.

In the technical scheme, the current collecting device 806 is used for collecting alternating current voltage and bus voltage, the average value of the maximum value of the alternating current voltage and the average value of the minimum value of the bus voltage is controlled to be reduced when a bus voltage backlash phenomenon occurs, and then the flux weakening current is calculated according to the reduced average value, the direct axis instruction voltage and the quadrature axis instruction voltage, so that flux weakening control over the motor is achieved. In the technical scheme, on one hand, by means of an adjusting mode of reducing the average value of the maximum value of the alternating voltage and the minimum value of the bus voltage, the weak magnetic current can be increased under the condition that the bus voltage is backflushed, the phenomenon that the current is out of control and the bus voltage is further backflushed due to insufficient aggravated voltage is avoided, and the fault shutdown is avoided; on the other hand, the problem that the weak magnetic current is larger due to lower available voltage caused by only utilizing the minimum value of the bus voltage to determine the weak magnetic current is solved.

In an embodiment of the third aspect of the present invention, a readable storage medium is provided, on which a program or an instruction is stored, and the program or the instruction is executed by a processor to implement the field weakening control method of the motor according to any one of the above technical solutions. The computer-readable storage medium includes a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and the like.

The readable storage medium, the program or the instructions provided by the present invention, when executed by the processor, implement the steps of the field weakening control method for the motor according to any one of the above technical solutions, and therefore the readable storage medium includes all the beneficial effects of the field weakening control method for the motor according to any one of the above technical solutions.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.