阅读说明：本技术 一种永磁同步电机弱磁控制方法、系统、设备和介质 (Method, system, equipment and medium for flux weakening control of permanent magnet synchronous motor ) 是由 汪凤翔 何龙 罗宇 杨钰敏 李政 于 2021-09-24 设计创作，主要内容包括：本发明实施例公开了一种永磁同步电机弱磁控制方法,其是一种基于有限集预测电流控制方法和实时电压反馈的混合弱磁控制策略,包括数据标定过程以及混合弱磁控制过程。首先,本发明实施例采用有限集预测电流控制方法在最大转矩电流比和弱磁区域中进行转矩、转速、电流和角度的标定,避免复杂调参过程影响标定数据的精度,提高标定数据的可靠性。其次,在预测电流方法基础上,结合实时电压反馈,设计弱磁区域的混合弱磁控制策略,避免电流环参数整定的同时,解决电压极限椭圆约束问题和实现高速运行。(The embodiment of the invention discloses a permanent magnet synchronous motor flux weakening control method, which is a mixed flux weakening control strategy based on a finite set prediction current control method and real-time voltage feedback, and comprises a data calibration process and a mixed flux weakening control process. Firstly, the embodiment of the invention calibrates the torque, the rotating speed, the current and the angle in the maximum torque-current ratio and the weak magnetic region by adopting a finite set prediction current control method, avoids the influence of a complex parameter adjusting process on the precision of calibration data, and improves the reliability of the calibration data. Secondly, on the basis of a current prediction method, a mixed flux weakening control strategy of a flux weakening area is designed by combining real-time voltage feedback, so that the problem of voltage limit ellipse restriction is solved and high-speed operation is realized while current loop parameter setting is avoided.)

1. A flux weakening control method for a permanent magnet synchronous motor is characterized by comprising the following steps: a data calibration process and a mixed weak magnetic control process;

the data calibration process comprises the steps of giving d-axis current i under different rotating speed conditions_dAnd q-axis current i_qWhile keeping the back EMF within the voltage limits, record i at that time_d、i_qFitting the formed flux linkage, rotating speed and torque data by using an interpolation method, and finally forming a rotating speed-torque-current data set by adopting a traversal algorithm;

the hybrid flux weakening control process comprises the following steps:

step B1, designing a table look-up module by adopting a rotating speed-torque-current data set obtained in the data calibration process, wherein the input of the table look-up module is torque and rotating speed, and the output is reference d-axis and q-axis currents;

step B2, under the constraint condition that the permanent magnet synchronous motor runs at high speed, calculating through a cost function according to reference d-axis and q-axis currents output by a table look-up module, and selecting an optimal switching vector applied to the permanent magnet synchronous motor;

and step B3, calculating the voltage applied to the permanent magnet synchronous motor by using the current and the rotating speed measured by the sensor, comparing the voltage with the maximum phase voltage to calculate a dynamic flux weakening parameter, and inhibiting the reference current output by the table look-up module according to whether the voltage on the motor is saturated or not by using the dynamic flux weakening parameter so as to control the voltage within a voltage limit ellipse.

2. The method of claim 1, wherein: the data calibration process specifically includes:

step A1, constructing a current loop control algorithm based on the prediction current control, dragging the drive motor to a set rotating speed by using a double-drag load motor, and inputting different currents i within the rated rotating speed_sAngle β, observed current i_sAnd recording i at that time_d、i_qObtaining maximum torque current ratio data within a rated rotating speed;

step A2, dragging the rotating speed of the driving motor to the rated rotating speed corresponding to the maximum torque measured in step A1 by the counter-dragging load motor, and adjusting the current i_sAnd an angle beta to make the voltage within the limit voltage range, and recording different rotating speeds and different currents i_sThe maximum torque corresponding to the sum angle β and i at that time_d、i_qWeak magnetic range data above a rated rotating speed is formed;

step A3, correlating the sampled torque and rotating speed with corresponding current to obtain an original data set;

a4, mapping the original data set to a three-dimensional coordinate system by using an interpolation method as a data fitting algorithm to obtain a preliminarily fitted data plane;

and A5, observing the preliminarily fitted plane, correcting incorrect data points, and obtaining a rotating speed-torque-current data set through a traversal algorithm.

3. The method according to claim 1, wherein the step B2 is specifically:

deducing according to current constraint and voltage constraint contained in the permanent magnet synchronous motor during high-speed operation to obtain a current prediction formula of the next control period:

wherein the content of the first and second substances,respectively the current in the d-q coordinate axis at the k-th moment, L_dAnd L_qAre the stator inductance parameter u in the d-q coordinate axis_dAnd u_qRespectively, the voltage in the d-q coordinate axis, R_sIs stator resistance, T_sIs the sampling period, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage;

taking the switch vector with the minimum distance to the reference current point as an optimal vector, introducing a cost function to select the optimal vector, wherein the calculation formula of the cost function is as follows:

wherein the content of the first and second substances,is a reference current for the d-axis,is the reference current of the q axis.

4. The method according to claim 1, wherein in step B3, the calculation formula of the dynamic flux weakening parameter is:

wherein u is_dcIs a DC bus voltage, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage i_d、i_qRespectively are currents under d-q coordinate axes; l is_d、L_qRespectively are stator inductance parameters under d-q coordinate axes.

5. A permanent magnet synchronous motor flux weakening control device is characterized by comprising: the device comprises a table look-up module, a limited set prediction current control module and a real-time voltage feedback module;

the table look-up module is designed by adopting a rotating speed-torque-current data set obtained in a data calibration process, the input of the table look-up module is torque and rotating speed, and the output of the table look-up module is reference d-axis and q-axis currents;

the data calibration process comprises the steps of giving d-axis current i under different rotating speed conditions_dAnd q-axis current i_qWhile keeping the back EMF within the voltage limits, record i at that time_d、i_qFitting the formed flux linkage, rotating speed and torque data by using an interpolation method, and finally forming a rotating speed-torque-current data set by adopting a traversal algorithm;

the limited set prediction current control module is used for calculating through a cost function according to reference d-axis and q-axis currents output by the table look-up module under the constraint condition that the permanent magnet synchronous motor runs at a high speed, and selecting an optimal switching vector applied to the permanent magnet synchronous motor;

the real-time voltage feedback module calculates the voltage applied to the permanent magnet synchronous motor by using the current and the rotating speed measured by the sensor, compares the voltage with the maximum phase voltage to calculate dynamic flux weakening parameters, and inhibits the reference current output by the table look-up module according to whether the voltage on the motor is saturated or not so as to control the voltage within a voltage limit ellipse.

6. The apparatus of claim 5, wherein: in the table look-up module, the data calibration process specifically includes:

step A1, constructing a current loop control algorithm based on the prediction current control, dragging the drive motor to a set rotating speed by using a double-drag load motor, and inputting different currents i within the rated rotating speed_sAngle β, observed current i_sAnd recording i at that time_d、i_qObtaining maximum torque current ratio data within a rated rotating speed;

step A2, dragging the rotating speed of the driving motor to the rated rotating speed corresponding to the maximum torque measured in step A1 by the counter-dragging load motor, and adjusting the current i_sAnd an angle beta to make the voltage within the limit voltage range, and recording different rotating speeds and different currents i_sThe maximum torque corresponding to the sum angle β and i at that time_d、i_qWeak magnetic range data above a rated rotating speed is formed;

step A3, correlating the sampled torque and rotating speed with corresponding current to obtain an original data set;

a4, mapping the original data set to a three-dimensional coordinate system by using an interpolation method as a data fitting algorithm to obtain a preliminarily fitted data plane;

and A5, observing the preliminarily fitted plane, correcting incorrect data points, and obtaining a rotating speed-torque-current data set through a traversal algorithm.

7. The apparatus of claim 5, wherein the finite set predictive current control module is specifically configured to:

deducing according to current constraint and voltage constraint contained in the permanent magnet synchronous motor during high-speed operation to obtain a current prediction formula of the next control period:

wherein the content of the first and second substances,respectively the current in the d-q coordinate axis at the k-th moment, L_dAnd L_qAre the stator inductance parameter u in the d-q coordinate axis_dAnd u_qRespectively, the voltage in the d-q coordinate axis, R_sIs stator resistance, T_sIs the sampling period, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage;

taking the switch vector with the minimum distance to the reference current point as an optimal vector, introducing a cost function to select the optimal vector, wherein the calculation formula of the cost function is as follows:

wherein the content of the first and second substances,is a reference current for the d-axis,is the reference current of the q axis.

8. The apparatus of claim 5, wherein in the real-time voltage feedback module, the calculation formula of the dynamic flux weakening parameter is as follows:

wherein u is_dcIs a DC bus voltage, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage i_d、i_qRespectively are currents under d-q coordinate axes; l is_d、L_qRespectively are stator inductance parameters under d-q coordinate axes.

9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method according to any of claims 1 to 4 when executing the program.

10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the method according to any one of claims 1 to 4.

Technical Field

The invention relates to the technical field of permanent magnet synchronous motors, in particular to a method, a system, equipment and a medium for controlling the field weakening of a permanent magnet synchronous motor.

Background

With the rapid development of the current intelligent manufacturing and equipment fields, the requirements for electrical machine performance such as high power density, high efficiency, low cost, smaller volume and the like are increasing. The embedded permanent magnet synchronous motor has the characteristics of high power density, high-speed operation and the like, can improve the speed regulation performance and the motor efficiency by utilizing the reluctance torque component, and is more and more widely applied to speed regulation driving systems with higher requirements.

As the motor speed increases, the back electromotive force of the motor increases, and the terminal voltage of the motor also increases. The operating range of the motor is constrained due to supply voltage limitations and current controller saturation effects. Therefore, the motor needs to be capable of operating well in a high-speed region, and needs to be operated at an increased speed by adopting weak magnetic control.

Various flux weakening control methods for permanent magnet synchronous motors have been developed at present, but the existing vector control method has the problems of large difference of controller parameters under different working conditions, complex space vector pulse width modulation and the like.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method, a system, equipment and a medium for controlling the flux weakening of a permanent magnet synchronous motor, and solves the problem of voltage limit ellipse restriction while avoiding current loop parameter setting through a mixed flux weakening control strategy integrating feedforward look-up table flux weakening, voltage feedback and a finite set prediction current control algorithm.

In a first aspect, the present invention provides a method for controlling field weakening of a permanent magnet synchronous motor, including: a data calibration process and a mixed weak magnetic control process;

the data calibration process comprises the steps of giving d-axis current i under different rotating speed conditions_dAnd q-axis current i_qWhile keeping the back EMF within the voltage limits, record i at that time_d、i_qFitting the formed flux linkage, rotating speed and torque data by using an interpolation method, and finally forming a rotating speed-torque-current data set by adopting a traversal algorithm;

the hybrid flux weakening control process comprises the following steps:

step B1, designing a table look-up module by adopting a rotating speed-torque-current data set obtained in the data calibration process, wherein the input of the table look-up module is torque and rotating speed, and the output is reference d-axis and q-axis currents;

step B2, under the constraint condition that the permanent magnet synchronous motor runs at high speed, calculating through a cost function according to reference d-axis and q-axis currents output by a table look-up module, and selecting an optimal switching vector applied to the permanent magnet synchronous motor;

and step B3, calculating the voltage applied to the permanent magnet synchronous motor by using the current and the rotating speed measured by the sensor, comparing the voltage with the maximum phase voltage to calculate a dynamic flux weakening parameter, and inhibiting the reference current output by the table look-up module according to whether the voltage on the motor is saturated or not by using the dynamic flux weakening parameter so as to control the voltage within a voltage limit ellipse.

Further, the data calibration process specifically includes:

step A1, constructing a current loop control algorithm based on the prediction current control, dragging the drive motor to a set rotating speed by using a double-drag load motor, and inputting different currents i within the rated rotating speed_sAngle β, observed current i_sAnd recording i at that time_d、i_qObtaining maximum torque current ratio data within a rated rotating speed;

step A2, dragging the rotating speed of the driving motor to the rated rotating speed corresponding to the maximum torque measured in step A1 by the counter-dragging load motor, and adjusting the current i_sAnd an angle beta to make the voltage within the limit voltage range, and recording different rotating speeds and different currents i_sThe maximum torque corresponding to the sum angle β and i at that time_d、i_qWeak magnetic range data above a rated rotating speed is formed;

step A3, correlating the sampled torque and rotating speed with corresponding current to obtain an original data set;

a4, mapping the original data set to a three-dimensional coordinate system by using an interpolation method as a data fitting algorithm to obtain a preliminarily fitted data plane;

and A5, observing the preliminarily fitted plane, correcting incorrect data points, and obtaining a rotating speed-torque-current data set through a traversal algorithm.

Further, the step B2 is specifically:

deducing according to current constraint and voltage constraint contained in the permanent magnet synchronous motor during high-speed operation to obtain a current prediction formula of the next control period:

wherein the content of the first and second substances,respectively the current in the d-q coordinate axis at the k-th moment, L_dAnd L_qAre the stator inductance parameter u in the d-q coordinate axis_dAnd u_qRespectively, the voltage in the d-q coordinate axis, R_sIs stator resistance, T_sIs the sampling period, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage;

taking the switch vector with the minimum distance to the reference current point as an optimal vector, introducing a cost function to select the optimal vector, wherein the calculation formula of the cost function is as follows:

wherein the content of the first and second substances,is a reference current for the d-axis,is the reference current of the q axis.

Further, in step B3, the calculation formula of the dynamic flux weakening parameter is:

wherein u is_dcIs a DC bus voltage, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage i_d、i_qRespectively are currents under d-q coordinate axes; l is_d、L_qRespectively are stator inductance parameters under d-q coordinate axes.

In a second aspect, the present invention provides a flux weakening control device for a permanent magnet synchronous motor, including: the device comprises a table look-up module, a limited set prediction current control module and a real-time voltage feedback module;

the table look-up module is designed by adopting a rotating speed-torque-current data set obtained in a data calibration process, the input of the table look-up module is torque and rotating speed, and the output of the table look-up module is reference d-axis and q-axis currents;

the data calibration process comprises the steps of giving d-axis current i under different rotating speed conditions_dAnd q-axis current i_qWhile keeping the back EMF within the voltage limits, record i at that time_d、i_qFitting the formed flux linkage, rotating speed and torque data by using an interpolation method, and finally forming a rotating speed-torque-current data set by adopting a traversal algorithm;

the limited set prediction current control module is used for calculating through a cost function according to reference d-axis and q-axis currents output by the table look-up module under the constraint condition that the permanent magnet synchronous motor runs at a high speed, and selecting an optimal switching vector applied to the permanent magnet synchronous motor;

the real-time voltage feedback module calculates the voltage applied to the permanent magnet synchronous motor by using the current and the rotating speed measured by the sensor, compares the voltage with the maximum phase voltage to calculate dynamic flux weakening parameters, and inhibits the reference current output by the table look-up module according to whether the voltage on the motor is saturated or not so as to control the voltage within a voltage limit ellipse.

Further, in the table lookup module, the data calibration process specifically includes:

step A1, constructing a current loop control algorithm based on the prediction current control, dragging the drive motor to a set rotating speed by using a double-drag load motor, and inputting different currents i within the rated rotating speed_sAngle β, observed current i_sAnd recording i at that time_d、i_qObtaining maximum torque current ratio data within a rated rotating speed;

step A2, dragging the rotating speed of the driving motor to the rated rotating speed corresponding to the maximum torque measured in step A1 by the counter-dragging load motor, and adjusting the current i_sAnd an angle beta to make the voltage within the limit voltage range, and recording different rotating speeds and different currents i_sThe maximum torque corresponding to the sum angle β and i at that time_d、i_qWeak magnetic range data above a rated rotating speed is formed;

step A3, correlating the sampled torque and rotating speed with corresponding current to obtain an original data set;

a4, mapping the original data set to a three-dimensional coordinate system by using an interpolation method as a data fitting algorithm to obtain a preliminarily fitted data plane;

and A5, observing the preliminarily fitted plane, correcting incorrect data points, and obtaining a rotating speed-torque-current data set through a traversal algorithm.

Further, the finite set predictive current control module is specifically configured to:

deducing according to current constraint and voltage constraint contained in the permanent magnet synchronous motor during high-speed operation to obtain a current prediction formula of the next control period:

wherein the content of the first and second substances,respectively the current in the d-q coordinate axis at the k-th moment, L_dAnd L_qStator poles in d-q coordinate axes, respectivelySensory parameter u_dAnd u_qRespectively, the voltage in the d-q coordinate axis, R_sIs stator resistance, T_sIs the sampling period, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage;

taking the switch vector with the minimum distance to the reference current point as an optimal vector, introducing a cost function to select the optimal vector, wherein the calculation formula of the cost function is as follows:

wherein the content of the first and second substances,is a reference current for the d-axis,is the reference current of the q axis.

Further, in the real-time voltage feedback module, a calculation formula of the dynamic flux weakening parameter is as follows:

wherein u is_dcIs a DC bus voltage, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage i_d、i_qRespectively are currents under d-q coordinate axes; l is_d、L_qRespectively are stator inductance parameters under d-q coordinate axes.

In a third aspect, the present invention provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of the first aspect when executing the program.

In a fourth aspect, the invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the method of the first aspect.

The technical scheme provided by the embodiment of the invention has the following technical effects or advantages:

firstly, the scheme provided by the patent adopts predictive current control to avoid the adjustment of complex PI parameters. Secondly, the scheme starts from a model prediction control principle, and calculates the optimal switch right amount of the inverter by using a cost function. Furthermore, the scheme also designs a dynamic weak magnetic parameter, and utilizes voltage feedback to limit the size of table lookup output current, thereby solving the problem of voltage limit constraint and improving the stability and safety of a control system.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

The invention will be further described with reference to the following examples with reference to the accompanying drawings.

FIG. 1 is a structural control diagram of the calibration algorithm of the present invention;

FIG. 2 is a control diagram of the overall structure of the algorithm of the present invention;

FIG. 3 is a block diagram of the system of the present invention;

FIG. 4 is a flow chart of a method according to one embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an apparatus according to a second embodiment of the present invention;

fig. 6 is a schematic structural diagram of an electronic device according to a third embodiment of the invention;

fig. 7 is a schematic structural diagram of a medium according to a fourth embodiment of the present invention.

Detailed Description

The embodiment of the invention provides a method, a system, equipment and a medium for controlling the flux weakening of a permanent magnet synchronous motor, and solves the problem of voltage limit ellipse restriction while avoiding current loop parameter setting through a mixed flux weakening control strategy integrating feedforward table flux weakening, voltage feedback and a finite set prediction current control algorithm.

The technical scheme in the embodiment of the invention has the following general idea:

firstly, the scheme adopts a finite set prediction current control method to calibrate the torque, the rotating speed, the current and the angle in the maximum torque-current ratio and the weak magnetic region, so that the influence of a complex parameter adjusting process on the precision of calibration data is avoided, and the reliability of the calibration data is improved. Secondly, the scheme starts from a model prediction control principle, and calculates the optimal switch proper amount of the inverter by using a cost function. Furthermore, on the basis of a current prediction method, a mixed weak magnetic control strategy of a weak magnetic area is designed by combining real-time voltage feedback, so that the problem of voltage limit ellipse restriction is solved while the current loop parameter setting is avoided, and the stability and the safety of a control system are improved.

In the scheme, two innovation points are mainly included. Firstly, a limited set prediction current control method is adopted for carrying out data calibration on a maximum torque current ratio control area and a weak magnetic control area of the motor for the first time. And secondly, designing a mixed weak magnetic control strategy which integrates feedforward table look-up weak magnetic, voltage feedback and a finite set prediction current control algorithm, wherein feedforward table look-up data in the strategy is derived from a data calibration extraction process in a first point.

Aiming at the first innovation point, the scheme adopts a finite set prediction current control algorithm, and the structure of the finite set prediction current control algorithm is shown in figure 1. The basic idea is to record i at different rotational speeds, given d-axis and q-axis currents, while ensuring that the back-emf is within the voltage limit_d、i_qThe formed flux linkage, speed and torque data form a speed-torque-current data set. The method comprises the following specific steps:

(1) constructing a current loop control algorithm based on prediction current control, dragging a driving motor to a certain rotating speed by using a double-dragging load motor, and inputting different currents i within a rated rotating speed_sAngle β, observed current i_sAnd recording i at that time_d、i_qAnd forming the maximum torque current ratio data within the rated rotating speed.

(2) Dragging the rotating speed of the driving motor to the rated rotating speed corresponding to the maximum torque measured in the step (1) by using a counter-dragging load motorRegulating the current i_sAnd an angle beta to make the voltage within the limit voltage range, and recording different rotating speeds and different currents i_sThe maximum torque corresponding to the sum angle β and i at that time_d、i_qAnd forming weak magnetic range data above the rated rotating speed.

(3) And correlating the sampled torque and rotating speed with the corresponding current to obtain an original data set.

(4) And mapping the original data set to a three-dimensional coordinate system by using an interpolation method as a data fitting algorithm to obtain a preliminarily fitted data plane.

(5) And observing the preliminarily fitted planes, correcting incorrect data points, and obtaining two final data fitting planes and tables through a traversal algorithm.

Through the steps, the obtained data comprises the full-speed domain information of the motor operation. Firstly, the data acquisition process is a progressive experimental calibration (including maximum torque current ratio calibration, turning speed calibration, no-load current calibration and flux weakening calibration), so that the smoothness and safety of the motor speed rise can be ensured. Secondly, due to the adoption of a finite set prediction current control method, the strategy avoids the influence of a complex parameter adjusting process on the precision of calibration data, and improves the calibration reliability.

Aiming at the second innovation point, the control loop shown in fig. 2 is designed on the basis of the calibration data. The control loop mainly comprises 3 modules, namely a Look-up Table (LUT) module, a finite set Prediction Current Control (PCC) module and a real-time voltage feedback module.

The design of the table look-up module is derived from a final data table in the innovation point one, and the input of the table look-up module is torque and rotating speed, and the output of the table look-up module is reference d-axis and q-axis currents.

The PCC module is designed by utilizing the derivation of a motor formula and the design of a cost function to select an optimal switching vector applied to the permanent magnet synchronous motor under the constraint condition that the permanent magnet synchronous motor runs at a high speed. The permanent magnet synchronous motor mainly comprises two constraints during high-speed operation: one is the current limit circle, represented by the circle in fig. 1; second is a voltage limit ellipse, represented by an ellipse in fig. 1; their mathematical representation is as follows:

in the formula: i.e. i_limAnd u_limRespectively the limiting current and the limiting back electromotive voltage of the motor u_dcIs the dc bus voltage. The dynamic stator voltage equation of the permanent magnet synchronous motor is as follows (2):

in the formula: u. of_dAnd u_qRespectively the voltage in the d-q coordinate axis, i_d、i_qRespectively are currents under d-q coordinate axes; l is_d、L_qStator inductance parameters under d-q coordinate axes respectively; r_sIs a stator resistor; psi_fIs a permanent magnet flux linkage; omega_eIs the electrical angular velocity.

And (3) performing a term shift on the formula to obtain differential equations of d-axis and q-axis currents:

according to the first-order euler formula:

the same can be obtained:

at this time, the reference current value in the control period can be calculated by a model of the motor, and the value is represented by a dot i in fig. 2_dqAnd (4) showing.

Since the strategy adopts a finite set control idea, two strategies are adoptedThe 8 switching states of the level inverter are converted into 7 switching vectors (two of which correspond to the same voltage vector), which correspond to V in the figure respectively₁To V₇Therefore, a cost function is introduced when the optimal vector is selected, as shown in formula (6):

the cost function takes the switching vector having the smallest distance to the point as the optimal output vector.

The real-time voltage feedback module calculates the voltage applied to the permanent magnet synchronous motor at the moment by using the current and the rotating speed measured by the sensor, and compares the voltage with the maximum phase voltage to obtain a parameter, which is called as a dynamic flux weakening parameter. The parameter can inhibit the reference current given by the table look-up module according to whether the voltage on the motor is saturated at the moment, and further the voltage is controlled to be within the voltage limit ellipse. The specific dynamic flux weakening parameter design is as follows:

the system architecture is shown in fig. 3. Through the design strategy, the problems of voltage limit ellipse constraint and complex current parameter adjustment in traditional control existing in the flux weakening and speed increasing of the permanent magnet synchronous motor can be solved, and meanwhile, the stability and safety of the permanent magnet synchronous motor in high-speed operation are improved in the actual operation process.

Example one

The embodiment provides a flux weakening control method for a permanent magnet synchronous motor, as shown in fig. 4, including: a data calibration process and a mixed weak magnetic control process;

the data calibration process comprises the steps of giving d-axis current i under different rotating speed conditions_dAnd q-axis current i_qWhile keeping the back EMF within the voltage limits, record i at that time_d、i_qForming flux linkage, rotation speed and torque data, and then interpolating the dataFitting, and finally forming a rotating speed-torque-current data set by adopting a traversal algorithm;

the hybrid flux weakening control process comprises the following steps:

step B1, designing a table look-up module by adopting a rotating speed-torque-current data set obtained in the data calibration process, wherein the input of the table look-up module is torque and rotating speed, and the output is reference d-axis and q-axis currents;

step B2, under the constraint condition that the permanent magnet synchronous motor runs at high speed, calculating through a cost function according to reference d-axis and q-axis currents output by a table look-up module, and selecting an optimal switching vector applied to the permanent magnet synchronous motor;

and step B3, calculating the voltage applied to the permanent magnet synchronous motor by using the current and the rotating speed measured by the sensor, comparing the voltage with the maximum phase voltage to calculate a dynamic flux weakening parameter, and inhibiting the reference current output by the table look-up module according to whether the voltage on the motor is saturated or not by using the dynamic flux weakening parameter so as to control the voltage within a voltage limit ellipse.

Among them, as a more preferred or more specific implementation manner of this embodiment:

the data calibration process specifically includes:

step A1, constructing a current loop control algorithm based on the prediction current control, dragging the drive motor to a set rotating speed by using a double-drag load motor, and inputting different currents i within the rated rotating speed_sAngle β, observed current i_sAnd recording i at that time_d、i_qObtaining maximum torque current ratio data within a rated rotating speed;

step A2, dragging the rotating speed of the driving motor to the rated rotating speed corresponding to the maximum torque measured in step A1 by the counter-dragging load motor, and adjusting the current i_sAnd an angle beta to make the voltage within the limit voltage range, and recording different rotating speeds and different currents i_sThe maximum torque corresponding to the sum angle β and i at that time_d、i_qWeak magnetic range data above a rated rotating speed is formed;

step A3, correlating the sampled torque and rotating speed with corresponding current to obtain an original data set;

a4, mapping the original data set to a three-dimensional coordinate system by using an interpolation method as a data fitting algorithm to obtain a preliminarily fitted data plane;

and A5, observing the preliminarily fitted plane, correcting incorrect data points, and obtaining a rotating speed-torque-current data set through a traversal algorithm.

The step B2 specifically includes:

deducing according to current constraint and voltage constraint contained in the permanent magnet synchronous motor during high-speed operation to obtain a current prediction formula of the next control period moment:

wherein the content of the first and second substances,respectively the current in the d-q coordinate axis at the k-th moment, L_dAnd L_qAre the stator inductance parameter u in the d-q coordinate axis_dAnd u_qRespectively, the voltage in the d-q coordinate axis, R_sIs stator resistance, T_sIs the sampling period, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage;

taking the switch vector with the minimum distance to the reference current point as an optimal vector, introducing a cost function to select the optimal vector, wherein the calculation formula of the cost function is as follows:

wherein the content of the first and second substances,is a reference current for the d-axis,is the reference current of the q axis.

In the step B3, the calculation formula of the dynamic flux weakening parameter is:

wherein u is_dcIs a DC bus voltage, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage i_d、i_qRespectively are currents under d-q coordinate axes; l is_d、L_qRespectively are stator inductance parameters under d-q coordinate axes.

Based on the same inventive concept, the application also provides a device corresponding to the method in the first embodiment, which is detailed in the second embodiment.

Example two

In the present embodiment, there is provided a flux weakening control device for a permanent magnet synchronous motor, as shown in fig. 5, including: the device comprises a table look-up module, a limited set prediction current control module and a real-time voltage feedback module;

the table look-up module is designed by adopting a rotating speed-torque-current data set obtained in a data calibration process, the input of the table look-up module is torque and rotating speed, and the output of the table look-up module is reference d-axis and q-axis currents;

the data calibration process comprises the steps of giving d-axis current i under different rotating speed conditions_dAnd q-axis current i_qWhile keeping the back EMF within the voltage limits, record i at that time_d、i_qFitting the formed flux linkage, rotating speed and torque data by using an interpolation method, and finally forming a rotating speed-torque-current data set by adopting a traversal algorithm;

the limited set prediction current control module is used for calculating through a cost function according to reference d-axis and q-axis currents output by the table look-up module under the constraint condition that the permanent magnet synchronous motor runs at a high speed, and selecting an optimal switching vector applied to the permanent magnet synchronous motor;

the real-time voltage feedback module calculates the voltage applied to the permanent magnet synchronous motor by using the current and the rotating speed measured by the sensor, compares the voltage with the maximum phase voltage to calculate dynamic flux weakening parameters, and inhibits the reference current output by the table look-up module according to whether the voltage on the motor is saturated or not so as to control the voltage within a voltage limit ellipse.

Among them, as a more preferred or more specific implementation manner of this embodiment:

in the table look-up module, the data calibration process specifically includes:

step A1, constructing a current loop control algorithm based on the prediction current control, dragging the drive motor to a set rotating speed by using a double-drag load motor, and inputting different currents i within the rated rotating speed_sAngle β, observed current i_sAnd recording i at that time_d、i_qObtaining maximum torque current ratio data within a rated rotating speed;

step A2, dragging the rotating speed of the driving motor to the rated rotating speed corresponding to the maximum torque measured in step A1 by the counter-dragging load motor, and adjusting the current i_sAnd an angle beta to make the voltage within the limit voltage range, and recording different rotating speeds and different currents i_sThe maximum torque corresponding to the sum angle β and i at that time_d、i_qWeak magnetic range data above a rated rotating speed is formed;

step A3, correlating the sampled torque and rotating speed with corresponding current to obtain an original data set;

a4, mapping the original data set to a three-dimensional coordinate system by using an interpolation method as a data fitting algorithm to obtain a preliminarily fitted data plane;

and A5, observing the preliminarily fitted plane, correcting incorrect data points, and obtaining a rotating speed-torque-current data set through a traversal algorithm.

The finite set prediction current control module is specifically configured to:

deducing according to current constraint and voltage constraint contained in the permanent magnet synchronous motor during high-speed operation to obtain a current prediction formula of the next control period:

wherein the content of the first and second substances,respectively the current in the d-q coordinate axis at the k-th moment, L_dAnd L_qAre the stator inductance parameter u in the d-q coordinate axis_dAnd u_qRespectively, the voltage in the d-q coordinate axis, R_sIs stator resistance, T_sIs the sampling period, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage;

taking the switch vector with the minimum distance to the reference current point as an optimal vector, introducing a cost function to select the optimal vector, wherein the calculation formula of the cost function is as follows:

wherein the content of the first and second substances,is a reference current for the d-axis,is the reference current of the q axis.

In the real-time voltage feedback module, the calculation formula of the dynamic flux weakening parameter is as follows:

wherein u is_dcIs a DC bus voltage, omega_eIs the electrical angular velocity, #_fIs a permanent magnet flux linkage i_d、i_qRespectively are currents under d-q coordinate axes; l is_d、L_qRespectively are stator inductance parameters under d-q coordinate axes.

Since the apparatus described in the second embodiment of the present invention is an apparatus used for implementing the method of the first embodiment of the present invention, based on the method described in the first embodiment of the present invention, a person skilled in the art can understand the specific structure and the deformation of the apparatus, and thus the details are not described herein. All the devices adopted in the method of the first embodiment of the present invention belong to the protection scope of the present invention.

Based on the same inventive concept, the application provides an electronic device embodiment corresponding to the first embodiment, which is detailed in the third embodiment.

EXAMPLE III

The present embodiment provides an electronic device, as shown in fig. 6, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, any implementation manner of the first embodiment may be implemented.

Since the electronic device described in this embodiment is a device used for implementing the method in the first embodiment of the present application, based on the method described in the first embodiment of the present application, a specific implementation of the electronic device in this embodiment and various variations thereof can be understood by those skilled in the art, and therefore, how to implement the method in the first embodiment of the present application by the electronic device is not described in detail herein. The equipment used by those skilled in the art to implement the methods in the embodiments of the present application is within the scope of the present application.

Based on the same inventive concept, the application provides a storage medium corresponding to the fourth embodiment, which is described in detail in the fourth embodiment.

Example four

The present embodiment provides a computer-readable storage medium, as shown in fig. 7, on which a computer program is stored, and when the computer program is executed by a processor, any one of the embodiments can be implemented.

Since the computer-readable storage medium described in this embodiment is a computer-readable storage medium used for implementing the method in the first embodiment of the present application, a person skilled in the art can understand a specific implementation manner of the computer-readable storage medium and various modifications thereof based on the method described in the first embodiment of the present application, and therefore, how to implement the method in the embodiment of the present application by using the computer-readable storage medium is not described in detail herein. Computer-readable storage media that can be used by those skilled in the art to implement the methods of the embodiments of the present application are all within the scope of the present application.

In the embodiment of the application, the adjustment of complex PI parameters is avoided by adopting predictive current control. Secondly, the scheme starts from a model prediction control principle, and calculates the optimal switch right amount of the inverter by using a cost function. Moreover, the scheme also designs a dynamic weak magnetic parameter, and utilizes voltage feedback to limit the size of table lookup output current, thereby solving the problem of voltage limit constraint and improving the stability and safety of a control system.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Although specific embodiments of the invention have been described above, it will be understood by those skilled in the art that the specific embodiments described are illustrative only and are not limiting upon the scope of the invention, and that equivalent modifications and variations can be made by those skilled in the art without departing from the spirit of the invention, which is to be limited only by the appended claims.