阅读说明：本技术 高压高速开关驱动电机控制方法 (Control method for high-voltage high-speed switch driving motor ) 是由 朱博 徐攀腾 严海健 谷裕 李建勋 宋述波 郑星星 李倩 杨学广 于 2021-07-14 设计创作，主要内容包括：本申请涉及一种高压高速开关驱动电机控制方法,该方法包括：通过获取电机运行参数和电机器件属性参数；基于电机运行参数确定滑模变量值,以及基于滑模变量值确定滑模面；将电机运行参数、电机器件属性参数、滑模变量值和滑模面输入至预设的第一控制模型中,得到目标电压；目标电压调节逆变器的输出电压,输出电压为电机的供电电压。也即是,本申请是根据电机的运行参数和电机器件属性参数,设计滑模面和第一控制模型,并由该滑模面和第一控制模型构建滑模控制器,滑模控制器根据电机运行参数和电机器件属性参数确定电机的目标电压。当逆变器的输出电压为该目标电压时,可以抑制逆变器非线性畸变电压导致的转矩脉动。(The application relates to a control method of a high-voltage high-speed switch driving motor, which comprises the following steps: obtaining motor operation parameters and motor device attribute parameters; determining a sliding mode variable value based on the motor operation parameters, and determining a sliding mode surface based on the sliding mode variable value; inputting motor operation parameters, motor device attribute parameters, sliding mode variable values and sliding mode surfaces into a preset first control model to obtain target voltage; the target voltage regulates an output voltage of the inverter, and the output voltage is a supply voltage of the motor. That is, according to the method, a sliding mode surface and a first control model are designed according to the operation parameters of the motor and the attribute parameters of the motor device, a sliding mode controller is constructed by the sliding mode surface and the first control model, and the sliding mode controller determines the target voltage of the motor according to the operation parameters of the motor and the attribute parameters of the motor device. When the output voltage of the inverter is the target voltage, torque ripple caused by the nonlinear distortion voltage of the inverter can be suppressed.)

1. A method of controlling a motor, the method comprising:

acquiring motor operation parameters and motor device attribute parameters;

determining a sliding mode variable value based on the motor operation parameters, and determining a sliding mode surface based on the sliding mode variable value;

inputting the motor operation parameters, the motor device attribute parameters, the sliding mode variable values and the sliding mode surface into a preset first control model to obtain target voltage; the target voltage is used for adjusting the output voltage of the inverter, and the output voltage is the power supply voltage of the motor.

2. The motor control method of claim 1, wherein the motor operating parameter comprises a stator phase current of the motor;

determining sliding mode variable values based on the motor operating parameters, comprising:

determining coordinate axis measuring current of the motor under a rotating coordinate system according to the stator phase current of the motor;

determining a current error value according to the coordinate axis measuring current under the rotating coordinate system and the coordinate axis target current of the motor under the rotating coordinate system;

and determining the sliding mode variable value according to the current error value and a preset current sliding mode surface function.

3. The motor control method according to claim 2, wherein the coordinate axis measurement current includes a direct axis measurement current and a quadrature axis measurement current; the coordinate axis target current comprises a direct axis target current and a quadrature axis target current;

the current error values include a direct-axis current error value between the direct-axis measured current and a direct-axis target current, and a quadrature-axis current error value between the quadrature-axis measured current and a quadrature-axis target current.

4. The motor control method according to claim 2 or 3, wherein the determining of the coordinate axis measurement current of the motor in the rotating coordinate system according to the stator phase current of the motor comprises:

converting the stator phase current of the motor into coordinate axis measuring current under a static coordinate system through a first transformation function;

and converting the coordinate axis measuring current in the static coordinate system into the coordinate axis measuring current in the rotating coordinate system through a second transformation function.

5. A method of controlling a motor according to claim 2 or 3, wherein the motor operating parameter comprises a rotor speed of the motor;

before determining a current error value according to the coordinate axis measured current and a coordinate axis target current of the motor in a rotating coordinate system, the motor control method further includes:

determining a rotation speed error value according to the rotor rotation speed of the motor and a preset target rotation speed;

and obtaining a coordinate axis target current of the motor under a rotating coordinate system according to a preset second control model and the rotating speed error value.

6. The motor control method of any of claims 1-3, wherein determining the sliding mode surface based on the sliding mode variable value comprises:

and inputting the sliding mode variable value and the sliding mode coefficient into a preset system sliding mode surface function to obtain the sliding mode surface.

7. A method of controlling a motor according to any of claims 1-3, wherein the motor operating parameters include stator phase current and rotor speed of the motor; the motor device attribute parameters comprise stator resistance, coordinate axis inductance under a rotating coordinate system and permanent magnet rotor flux linkage; the sliding mode variable values comprise straight axis sliding mode variable values and quadrature axis sliding mode variable values; the sliding mode surface comprises a straight-axis sliding mode surface and a quadrature-axis sliding mode surface; the first control model comprises a direct-axis current control function and a quadrature-axis current control function; the target voltages comprise a direct-axis target voltage and a quadrature-axis target voltage;

correspondingly, the inputting the motor operation parameter, the motor device attribute parameter, the sliding mode variable value and the sliding mode surface into a preset first control model to obtain a target voltage includes:

taking the direct-axis measured current, the quadrature-axis measured current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under the rotating coordinate system, the direct-axis sliding mode variable and the direct-axis sliding mode surface as the input of the direct-axis current control function, and outputting the direct-axis target voltage through the direct-axis current control function; the direct axis measurement current and the quadrature axis measurement current are determined from stator phase currents of the motor;

and taking the direct axis measuring current, the quadrature axis measuring current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under the rotating coordinate system, the permanent magnet rotor flux linkage, the quadrature axis sliding mode variable value and the quadrature axis sliding mode surface as the input of the quadrature axis current control function, and outputting the quadrature axis target voltage through the quadrature axis current control function.

8. The motor control method according to claim 7, further comprising:

converting the direct axis target voltage and the quadrature axis target voltage into coordinate axis target voltages under a static coordinate system through inverse transformation of a second transformation function;

performing pulse width modulation on the coordinate axis target voltage under the static coordinate system to obtain a switching signal of the inverter module; the switching signal is used for adjusting the output voltage of the inverter, and when the inverter supplies power to the motor by using the output voltage, the actual rotor rotating speed of the motor is the same as the preset target rotating speed.

9. A computer arrangement comprising a memory and a processor, the memory storing a computer program, characterized in that the processor realizes the steps of the motor control method according to any of claims 1 to 8 when executing the computer program.

10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the motor control method according to any one of claims 1 to 8.

Technical Field

The application relates to the technical field of motor control, in particular to a control method for a high-voltage high-speed switch driving motor.

Background

In the power industry, motors are used as main devices for electric energy production, transmission and application, and are widely applied to the aspects of agriculture, industrial and mining enterprises, national defense, traffic and transportation industry, scientific culture, daily life and the like.

Taking a Permanent Magnet Synchronous Motor (PMSM) as an example, the PMSM has superior performances of simple structure, small volume, light weight, high power factor and the like, and completely meets the requirements of a modern high-performance servo system on high precision, good stability and high response speed in the aspects of structure, efficiency, control performance and the like. In order to enable the permanent magnet synchronous motor to be applied to the field of precise driving, the permanent magnet synchronous motor is required to provide smaller torque ripple, however, the permanent magnet synchronous motor is powered by a three-phase voltage source inverter in the driving process, the output voltage of the three-phase voltage source inverter has nonlinear distortion, and the nonlinear distortion voltage can cause the current of the permanent magnet synchronous motor to be distorted, so that the permanent magnet synchronous motor generates larger torque ripple, the performance of the permanent magnet synchronous motor is influenced, and the loss of the permanent magnet synchronous motor is increased.

Therefore, a method for suppressing the generation of large torque ripple in the permanent magnet synchronous motor is needed.

Disclosure of Invention

In view of the above, it is necessary to provide a method for controlling a high-voltage high-speed switching drive motor capable of effectively suppressing torque ripple.

In one aspect, a motor control method is provided, including:

acquiring motor operation parameters and motor device attribute parameters;

determining a sliding mode variable value based on the motor operation parameters, and determining a sliding mode surface based on the sliding mode variable value;

inputting motor operation parameters, motor device attribute parameters, sliding mode variable values and sliding mode surfaces into a preset first control model to obtain target voltage; the target voltage is used for regulating the output voltage of the inverter, and the output voltage is the power supply voltage of the motor.

In one embodiment, the motor operating parameter comprises a stator phase current of the motor;

determining sliding mode variable values based on the motor operating parameters, including:

determining coordinate axis measurement current of the motor under a rotating coordinate system according to the stator phase current of the motor;

determining a current error value according to the coordinate axis measuring current under the rotating coordinate system and the coordinate axis target current of the motor under the rotating coordinate system;

and determining a sliding mode variable value according to the current error value and a preset current sliding mode surface function.

In one embodiment, the coordinate axis measurement current comprises a direct axis measurement current and a quadrature axis measurement current; the coordinate axis target current comprises a direct axis target current and a quadrature axis target current;

the current error values include a direct-axis current error value between the direct-axis measured current and the direct-axis target current, and a quadrature-axis current error value between the quadrature-axis measured current and the quadrature-axis target current.

In one embodiment, determining the coordinate axis measurement current of the motor in the rotating coordinate system according to the stator phase current of the motor comprises:

converting the stator phase current of the motor into coordinate axis measuring current under a static coordinate system through a first transformation function;

and converting the coordinate axis measuring current in the static coordinate system into the coordinate axis measuring current in the rotating coordinate system through a second transformation function.

In one embodiment, the motor operating parameter comprises a rotor speed of the motor;

before determining a current error value according to the coordinate axis measured current and a coordinate axis target current of the motor in a rotating coordinate system, the motor control method further comprises the following steps:

determining a rotation speed error value according to the rotor rotation speed of the motor and a preset target rotation speed;

and obtaining the coordinate axis target current of the motor in the rotating coordinate system according to a preset second control model and the rotating speed error value.

In one embodiment, determining the sliding mode surface based on the sliding mode variable value comprises:

and inputting the sliding mode variable value and the sliding mode coefficient into a preset system sliding mode surface function to obtain a sliding mode surface.

In one embodiment, the motor operating parameters include a stator phase current and a rotor speed of the motor; the motor device attribute parameters comprise stator resistance, coordinate axis inductance under a rotating coordinate system and permanent magnet rotor flux linkage; the sliding mode variable value comprises a direct axis sliding mode variable value and an orthogonal axis sliding mode variable value; the slip form surface comprises a straight-axis slip form surface and a quadrature-axis slip form surface; the first control model comprises a direct-axis current control function and a quadrature-axis current control function; the target voltage comprises a direct-axis target voltage and a quadrature-axis target voltage;

correspondingly, inputting the motor operation parameters, the motor device attribute parameters, the sliding mode variable values and the sliding mode surfaces into a preset first control model to obtain target voltage, wherein the method comprises the following steps:

taking the direct-axis measured current, the quadrature-axis measured current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under a rotating coordinate system, the direct-axis sliding mode variable and the direct-axis sliding mode surface as the input of a direct-axis current control function, and outputting a direct-axis target voltage through the direct-axis current control function; the direct-axis measuring current and the quadrature-axis measuring current are determined according to the stator phase current of the motor;

and taking the direct-axis measurement current, the quadrature-axis measurement current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under a rotating coordinate system, the permanent magnet rotor flux linkage, the quadrature-axis sliding mode variable value and the quadrature-axis sliding mode surface as the input of a quadrature-axis current control function, and outputting a quadrature-axis target voltage through the quadrature-axis current control function.

In one embodiment, the motor control method further includes:

converting the direct axis target voltage and the quadrature axis target voltage into coordinate axis target voltage under a static coordinate system through inverse transformation of a second transformation function;

performing pulse width modulation on a coordinate axis target voltage under a static coordinate system to obtain a switching signal of the inverter module; the switching signal is used for adjusting the output voltage of the inverter, and when the inverter supplies power to the motor by using the output voltage, the actual rotor rotating speed of the motor is the same as the preset target rotating speed.

In another aspect, there is provided a motor control apparatus including:

the acquisition module is used for acquiring motor operation parameters and motor device attribute parameters;

the determining module is used for determining a sliding mode variable value based on the motor operation parameters and determining a sliding mode surface based on the sliding mode variable value;

the control module is used for inputting the motor operation parameters, the motor device attribute parameters, the sliding mode variable values and the sliding mode surfaces into a preset first control model to obtain target voltage; the target voltage regulates an output voltage of the inverter, and the output voltage is a supply voltage of the motor.

In another aspect, a computer device is provided, which includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of any one of the motor control methods provided in the above aspect when executing the computer program.

In another aspect, a computer-readable storage medium is provided, on which a computer program is stored, which, when being executed by a processor, implements the steps of any one of the motor control methods provided in the above-mentioned aspect.

The control method of the high-voltage high-speed switch driving motor obtains motor operation parameters and motor device attribute parameters; determining a sliding mode variable value based on the motor operation parameters, and determining a sliding mode surface based on the sliding mode variable value; inputting motor operation parameters, motor device attribute parameters, sliding mode variable values and sliding mode surfaces into a preset first control model to obtain target voltage; the target voltage regulates an output voltage of the inverter, and the output voltage is a supply voltage of the motor. That is, in the motor control process, the sliding mode controller designed according to the motor parameters to be controlled can output the target voltage of the driving motor under the condition of inputting the motor operation parameters and the motor device attribute parameters. In this way, when the output voltage of the inverter is the target voltage, the nonlinear distortion voltage output by the inverter can be eliminated, and when the inverter drives the motor based on the target voltage, the motor can be made to output a stable torque.

Drawings

FIG. 1 is a schematic diagram of a motor control system according to an embodiment of the present application;

FIG. 2 is a schematic flow chart of a motor control method according to an embodiment of the present application;

FIG. 3 is a schematic diagram illustrating a transformation from a three-phase coordinate system to a two-phase coordinate system according to an embodiment of the present application;

FIG. 4 is a schematic flow chart of a motor control method according to another embodiment of the present application;

FIG. 5 is a schematic flow chart of a motor control method according to another embodiment of the present application;

FIG. 6 shows PMSM vector control (i) in an embodiment of the present application_d0) structural principle schematic diagram;

FIG. 7 is a schematic flow chart of a motor control method according to another embodiment of the present application;

fig. 8 is a block diagram of a motor control apparatus according to an embodiment of the present application;

fig. 9 is an internal structural diagram of a computer device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

Before explaining the control method of the motor provided by the present application, technical terms and application backgrounds related to the present application will be explained.

A PID controller: a Proportional-Integral-Derivative (PID) controller is a feedback loop component that is common in industrial Control applications and consists of a Proportional regulator unit P, an Integral regulator unit I and a Derivative regulator unit D. Setting a proportionality coefficient K_pIntegral time constant K_iAnd a differential time constant K_dThe PID controller compares the collected actual output value with a reference value to obtain an error value, and then calculates a new input value by using the error value, wherein the new input value can enable the data of the system to reach or keep the reference value.

In the PID control system, the control system is composed of a PID controller, a controlled object, and a measuring element. The measuring element is used for measuring the output value of the controlled object, and the given reference value and the actual output value of the controlled object are used as the input of the PID controller, namely, the error value is the reference value-the output value of the controlled object. The error value is the input of the PID controller, the output of the PID controller is the new input value of the controlled object, and after the new input value acts on the controlled object, the output value of the controlled object is kept consistent with the reference value. The PID controller is a linear controller, and is mainly suitable for a system with basically linear and dynamic characteristics which do not change along with time.

Permanent magnet synchronous machine: the permanent magnet synchronous motor is a motor which uses permanent magnets to replace direct current excitation as constant excitation. The body of the motor consists of a stator and a rotor. The stator of the permanent magnet synchronous motor refers to a fixed part of the motor during operation, and compared with a common synchronous motor, the stator of the permanent magnet synchronous motor is basically consistent in structure and mainly comprises three-phase stator windings, silicon steel punching sheets, a shell for fixing an iron core and the like, wherein the three-phase stator windings, the silicon steel punching sheets and the shell are symmetrically distributed in a groove. When the three-phase stator winding is connected with a three-phase power supply which is symmetrical in time, a space rotating magnetic field can be generated in an air gap of the permanent magnet synchronous motor.

The rotor of a permanent magnet synchronous machine refers to a portion of an electric motor that can rotate when the electric motor is operated. The main difference between the permanent magnet synchronous motor and other motors is the rotor magnetic circuit structure, which replaces the electric excitation with the permanent magnet on the rotor, thereby saving the excitation coil, the slip ring and the electric brush and simplifying the structure. In general, the field of a permanent magnet synchronous machine can be regarded as constant and interacts with a rotating magnetic field generated by three-phase symmetrical current passing through a stator winding to generate torque.

In order to enable the permanent magnet synchronous motor to be applied to the field of precision driving, the permanent magnet synchronous motor is required to provide small torque ripple, low vibration frequency and low noise. However, the permanent magnet synchronous motor generates torque ripple caused by cogging torque, back electromotive force harmonics and commutation due to its own structure and control mode characteristics. Similarly, a sensor sampling link and a power converter in a permanent magnet synchronous motor driving system can also cause nonlinear external disturbance, and further torque pulsation is generated.

The permanent magnet synchronous motor is powered by a three-phase voltage source inverter in the driving process, the stator current is distorted due to nonlinear distortion voltage output by the inverter, the distorted current interacts with a rotor magnetic field, and therefore generated torque pulsation is a main mode influencing the performance of the permanent magnet synchronous motor. Therefore, in order to ensure the normal operation of the permanent magnet synchronous motor, a corresponding control strategy is required to control the output voltage of the inverter so as to control the power supply voltage of the permanent magnet synchronous motor, so that the permanent magnet synchronous motor outputs stable torque.

At present, control strategies applied to the driving process of a permanent magnet synchronous motor can be roughly divided into three categories:

(1) control strategies for the digital model of permanent magnet synchronous machines, i.e. traditional control strategies such as: PID feedback control, vector control, direct torque control, and the like. The PID control algorithm contains past, present and future information in the dynamic control process, is the most basic control method, is widely applied, is combined with other novel control ideas to form a plurality of valuable control strategies, and is the simplest and most effective to adopt PID control under the conditions that an object model is determined, unchanged and linear and operating conditions and operating environments are determined to be unchanged.

(2) Control strategies based on modern control theory, such as: adaptive control, sliding mode control (also called sliding mode variable structure control), robust control, predictive control and the like, and the modern control strategy takes the structure and parameter change of a controlled object, the influence of various nonlinearities, the change of an operating environment, environmental interference and other time-varying and uncertain factors into consideration.

(3) Control strategies based on intelligent control concepts, such as: fuzzy control, neural network control, expert control, genetic algorithms, and the like. The intelligent control strategy has the advantages of independence on a digital model of a controlled object and strong robustness, and can well overcome the influence of uncertain factors such as model parameter change, nonlinearity and the like in a motor control system.

In the three control strategies, the traditional PID control is the simplest and most effective, but the PID control based purely on the motor mathematical model has a great weakness, namely, the PID control is inevitably affected by the change of the motor parameter, and the knowledge of the permanent magnet synchronous motor mathematical model is still to be improved.

A good control system must have the rapidity of response, stability, robustness to system disturbances and system parameter changes. Because the speed regulation control system of the permanent magnet synchronous motor is a multivariable, nonlinear and strongly coupled complex system, model parameters of the system have uncertainty, the requirement on a control strategy is high, and the traditional cascade PID control method is not suitable for a more complicated nonlinear working condition. The ideal control strategy not only needs to meet the good dynamic and static performances of the system, but also has strong robustness for coping with the load disturbance and the motor parameter change of the system.

The sliding mode control belongs to the category of modern control, has low requirement on the accuracy of a mathematical model in a motor control system, has complete self-adaptability to uncertain parameters, variable parameters, inaccuracy of mathematical description and disturbance of an external environment of the system, shows good application prospect in the field of control systems of alternating current motors (permanent magnet synchronous motors belong to alternating current motors), has simple algorithm, is easy to realize in engineering, and can be applied to the motor control system.

Sliding mode control: sliding Mode Control (SMC), also called variable structure Control, is essentially a special class of nonlinear Control, with nonlinearities appearing as discontinuities in Control. The control method is different from other controls in that the 'structure' of the system is not fixed, but can be purposefully and continuously changed in a dynamic process according to the current state of the system (such as deviation, various derivatives thereof and the like), so that the system is forced to move according to the state track of a preset 'sliding surface'. The sliding surface can be designed and is irrelevant to the parameters and the disturbance of an object, so that the sliding mode control has the advantages of quick response, insensitive corresponding parameter change and disturbance, no need of system online identification, simple physical realization and the like.

The design process of the sliding mode controller comprises the following steps: determining a state equation of a controlled object, setting a sliding mode surface according to the state equation, and determining an output function of a sliding mode controller when the system state tends to 0 along the sliding mode surface.

Aiming at the problem that the torque pulsation of the permanent magnet motor can be generated by the inverter due to nonlinear output distortion voltage in the driving process of the permanent magnet synchronous motor, the sliding mode controller can be adopted in the motor control system to determine the target voltage output by the inverter, and the voltage is used for driving the permanent magnet synchronous motor to achieve the effect of inhibiting the torque pulsation.

After the technical terms and the application background related to the present application are introduced, a specific application environment of the motor control method of the present application is described below with reference to fig. 1.

The motor control method provided by the application can be applied to a motor control system shown in fig. 1. In the motor control system, an inverter supplies power to the motor, so that the normal operation of the motor is ensured. As shown in fig. 1, the motor control system 100 includes a parameter collector 110, a rotational speed controller 120 controlling an outer loop, a current controller 130 controlling an inner loop, and an inverter 140. The outer ring controls the rotation speed of the rotor in the motor, so that the measured rotation speed of the rotor can track the preset target rotation speed. The inner loop controls the stator phase current of the motor so that the measured current can track the target current.

The parameter collector 110 is used to collect operation parameters and device attribute parameters of the motor, and may be disposed in the motor or disposed at an output end or an input end of the motor, wherein the parameter collector is used to collect stator phase current of the motor when disposed at the input end of the motor, and is used to collect rotor speed of the motor when disposed at the output end of the motor.

In particular, the parameter collector 110 may be an encoder, a rotary transformer or other hall sensor.

The rotation speed controller 120 may be a conventional PID controller, a sliding mode controller, or another neural network controller, and the like, which is not limited in the embodiment of the present application. Since the PID controller is not suitable for complicated nonlinear working conditions, the current controller 130 in the embodiment of the present application may be a sliding mode controller designed according to the controlled motor to better determine the target voltage of the driving motor through the sliding mode controller.

In one possible implementation, the rotational speed controller 120 is configured to control the rotational speed of the rotor of the electric machine according to the rotational speed ω of the rotor and a preset target rotational speed ω^*Determining a coordinate axis target current i of the motor in a rotating coordinate system^*. The current controller 130 targets the current i according to the coordinate axis of the rotating coordinate system^*And the actual stator phase current i of the motor, determining the target voltage u for driving the motor^*And modulating the pulse width of the target voltage to obtain a switching signal of the inverter 140, and further controlling the conduction and the closing of a switching tube in the inverter 140 through the switching signal, so that the driving voltage (input voltage of the motor) of the motor output by the inverter 140 is the target voltage, and the motor will operate according to a preset target rotating speed. In this process, by controlling the output voltage of the inverter 140 to be a three-phase symmetrical sine wave voltage, inversion can be suppressedThe nonlinear distortion voltage output by the inverter 140 enables the motor to output stable torque.

Further, the rotor rotation speed ω and the preset target rotation speed ω^*And a coordinate axis target current i^*The error between the actual stator phase current i and the actual stator phase current i can be compared and calculated by a comparator, which is not limited by the embodiment of the present application.

Based on the motor control system 100, in a possible implementation manner, the rotation speed controller 120 and the current controller are integrated into a Digital Signal Processing (DSP) controller to be implemented, and a software program embedded in the DSP invokes corresponding functional units, specific algorithms, and the like to perform work. The specific implementation process refers to the following embodiment corresponding to fig. 2. After the DSP outputs a switching signal, the switching signal is isolated by an optical coupler, and then the switching tube in the inverter 140 is controlled to be turned on and off.

Based on the above motor control system, the motor control method of the present application will be explained with reference to the drawings.

In one embodiment, as shown in FIG. 2, a motor control method is provided that may be applied to the motor control system shown in FIG. 1. Specifically, the motor control method includes the steps of:

step 210: and acquiring motor operation parameters and motor device attribute parameters.

The motor operating parameters include, but are not limited to: the rotor speed of the motor and the stator phase current of the motor. The rotor rotating speed is the angular speed of clockwise rotation of the rotor, the stator phase current is three-phase symmetrical current introduced into the stator winding, and the stator phase current comprises stator phase A current, stator phase B current and stator phase C current.

The motor device property parameters include, but are not limited to: stator resistance, coordinate axis inductance under a rotating coordinate system and permanent magnet rotor flux linkage.

In the permanent magnet synchronous motor, the resistance values of the three-phase windings of the stator are the same.

In order to make the stator calculation equivalent to the rotor-based calculation, the three-phase coordinate system may be equivalent to a two-phase rotating coordinate system capable of generating a rotating magnetic field, the two-phase rotating coordinate system is fixed to the motor rotor, and the rotating magnetomotive force generated by the coordinate axis current in the two-phase rotating coordinate system is the same as the rotating magnetomotive force generated by the stator phase a current, the stator phase B current and the stator phase C current in the three-phase coordinate system.

And the coordinate axis inductance under the rotating coordinate system is equivalent inductance determined by the self-inductance coefficient and the inter-phase mutual inductance coefficient of the stator winding in the three-phase coordinate system.

The rotor permanent magnet can generate counter electromotive force in each phase of stator winding, the stator flux linkage is generated by the stator phase current and the rotor permanent magnet together, the flux linkage generated by the stator phase current is related to the position angle of the rotor, and the permanent magnet rotor flux linkage in the application is the flux linkage generated by the permanent magnet on the rotor.

Step 220: and determining a sliding mode variable value based on the motor operation parameters, and determining a sliding mode surface based on the sliding mode variable value.

When the target output voltage of the inverter is determined by adopting sliding mode control, a corresponding sliding mode surface is set according to the system state required to be controlled.

Specifically, a sliding mode variable value is determined according to the stator phase current, and then a sliding mode surface corresponding to the sliding mode variable is further set based on the determined sliding mode variable value.

In the motor control process, after the system state reaches the sliding mode surface, the system state can reach the balance state according to the track of the sliding mode surface. That is, in the process of controlling the current, the stator phase current can be smoothly adjusted to the target current through the sliding mode surface based on the target current stator phase current.

Step 230: and inputting the motor operation parameters, the motor device attribute parameters, the sliding mode variable values and the sliding mode surfaces into a preset first control model to obtain target voltage.

The first control model is internally provided with a sliding mode control algorithm, the target voltage is used for adjusting the output voltage of the inverter, and the output voltage is the power supply voltage of the motor.

Specifically, a sliding mode surface is designed according to the operation parameters of the motor, a first control model is designed according to the operation parameters of the motor, the device attribute parameters of the motor and the sliding mode control surface, and the sliding mode surface and the first control model form a sliding mode controller for controlling the driving current of the motor. In the motor control process, the sliding mode controller can output the target voltage of the driving motor under the condition of inputting the motor operation parameters and the motor device attribute parameters.

In the embodiment of the application, motor operation parameters and motor device attribute parameters are obtained; determining a sliding mode variable value based on the motor operation parameters, and determining a sliding mode surface based on the sliding mode variable value; inputting motor operation parameters, motor device attribute parameters, sliding mode variable values and sliding mode surfaces into a preset first control model to obtain target voltage; the target voltage regulates an output voltage of the inverter, and the output voltage is a supply voltage of the motor. That is, in the motor control process, the sliding mode controller designed according to the parameters of the motor to be controlled can output the target voltage of the driving motor under the condition of inputting the motor operation parameters and the motor device attribute parameters. In this way, when the output voltage of the inverter is the target voltage, the nonlinear distortion voltage output by the inverter can be eliminated, and when the inverter drives the motor based on the target voltage, the motor can be made to output a stable torque.

Based on the above embodiments, the embodiments of the present application take a permanent magnet synchronous motor as an example, and further explain the steps of the motor control method.

The permanent magnet synchronous motor is actually a nonlinear, multivariable and strongly coupled system, and the inductance coefficient of a stator and a rotor changes along with the change of the position of the rotor. The mathematical model of the permanent magnet synchronous motor contains time-varying parameters, and the stator of the permanent magnet synchronous motor is similar to the stator of the common electrically excited three-phase synchronous motor. If the induced electromotive force (counter electromotive force) generated by the permanent magnet is sinusoidal as well as the induced electromotive force generated by the exciting coil, the mathematical model of the permanent magnet synchronous motor is substantially the same as that of the electrically excited synchronous motor.

In analyzing a permanent magnet synchronous motor, the following assumptions are made for the motor:

(1) the back emf is sinusoidal;

(2) the stator magnetic field is distributed in a sine mode, and harmonic waves and saturation are not considered;

(3) eddy current and magnetic hysteresis loss are not counted;

(4) the rotor is not provided with damping windings, and the permanent magnets have no damping function.

When the change of parameters of a permanent magnet synchronous motor control system is neglected, the dynamic characteristic of the rotor rotating speed of the permanent magnet synchronous motor depends on the characteristic of output torque when the load torque is constant. If the torque can be accurately controlled, the permanent magnet synchronous motor control system can obtain smaller dynamic speed drop and shorter recovery time when the load is disturbed. Therefore, the key to the quality of the driving performance of the permanent magnet synchronous motor is the quality of the electromagnetic torque control.

The basic equations of the permanent magnet synchronous motor comprise a voltage equation, a flux linkage equation, a torque equation and the like of the motor, and the equations are the basis of a mathematical model of the permanent magnet synchronous motor.

The voltage equation of the permanent magnet synchronous motor is as follows:

the flux linkage equation of the permanent magnet synchronous motor is as follows:

the torque equation of the permanent magnet synchronous motor is as follows:

in the basic equation of the permanent magnet synchronous motor (A-B-C three-phase coordinate system) described above, u_A、u_BAnd u_CThe voltage of a three-phase stator winding of the permanent magnet synchronous motor; i.e. i_A、i_BAnd i_CIs the stator phase current of the permanent magnet synchronous motor; psi_A、ψ_BAnd psi_CA flux linkage for a three-phase stator winding; r_A＝R_B＝R_CR represents the stator phase resistance; psi_fMagnetic flux linkage generated for permanent magnets on the rotor; theta represents the electrical angle between the rotor axis and the stator A-phase winding axis, p_nThe number of pole pairs of the permanent magnet synchronous motor is shown.

As can be known from the torque equation (3) of the permanent magnet synchronous motor, the control system of the permanent magnet synchronous motor is a multivariable, nonlinear and strong coupling system. Based on the established mathematical model of the permanent magnet synchronous motor, the torque of the permanent magnet synchronous motor is controlled by a vector control method.

The basic idea of vector control is to try to simulate the torque control law of a direct current motor on a common three-phase alternating current motor, and on a magnetic field orientation coordinate, a current vector is decomposed into an excitation current component for generating magnetic flux and a torque current component for generating torque, the two components are perpendicular to each other and independent of each other, and then are respectively adjusted, so that the torque control of the alternating current motor is similar to that of the direct current motor in principle and characteristic. The key to vector control is therefore the control of the magnitude and spatial position (frequency and phase) of the current vector.

The purpose of vector control is to improve torque control performance, while the final implementation still falls on controlling the stator current (ac) flow. Because each physical quantity (voltage, current, electromotive force and magnetomotive force) on the stator side is an alternating current quantity, a space vector rotates at a synchronous rotating speed in space, and the adjustment, the control and the calculation are inconvenient. Therefore, each physical quantity needs to be converted from a static coordinate system to a synchronous rotating coordinate system by means of coordinate transformation, each space vector of the motor becomes a static vector when observed on the synchronous rotating coordinate system, each space vector on the synchronous coordinate system becomes a direct current quantity, the relation between each component of the torque and the controlled quantity can be found according to several forms of a torque formula, and each component value, namely the direct current given quantity, of the controlled vector required by the torque control can be calculated in real time. The control performance of the DC motor can be achieved by real-time control according to the given quantities. Since these dc set quantities are physically nonexistent and imaginary, they must be transformed from the rotating coordinate system back to the stationary coordinate system by an inverse coordinate transformation process to convert the dc set quantities into actual ac set quantities, which are controlled on the three-phase stator coordinate system to make their actual values equal to the set values.

There are two common coordinate systems used in vector control, one is a stationary coordinate system and the other is a rotating coordinate system.

(1) Two-phase stator coordinate system (alpha-beta coordinate system)

The stator has three-phase windings, each of which is A, B, C, which are separated from each other by 120 ° in electrical space, thereby forming an a-B-C three-phase coordinate system, as shown in fig. 3 (a). The axis of the α - β coordinate system is placed on the stator with the α axis coincident with the a axis and the β axis 90 ° advanced from the α axis, as shown in fig. 3 (b). Since the α -axis is fixed to the stator phase a winding axis, the α - β coordinate system is also a stationary coordinate system.

One rotating vector is transformed from the three-phase stator coordinate system (a-B-C coordinate system) to the stator two-phase stationary coordinate system (α - β coordinate system), called Clark transformation or 3/2 transformation, as shown in the following equation (4):

the inverse transformation is Clark inverse transformation or 2/3 transformation, and is shown in the following formula (5):

wherein i in the above formula (4) and formula (5)_A、i_BAnd i_CIs the three-phase stator phase current of the motor, i_αAnd i_βThe equivalent stator two-phase current.

(2) Rotor coordinate system (d-q coordinate system)

The rotor coordinate system is fixed to the rotor with the d-axis (the straight axis) on the rotor axis and the q-axis (the quadrature axis) leading the d-axis by 90 ° counterclockwise as shown in fig. 3 (c). The coordinate system rotates in space with the rotor at the rotor angular velocity, and is therefore a rotating coordinate system. For a permanent magnet synchronous motor, the d-axis is the axis of the rotor permanent magnet poles.

One rotation vector is transformed from a two-phase stationary coordinate system (α - β coordinate system) to a two-phase rotating coordinate system (d-q coordinate system), called Park transformation or rotation transformation, as shown in fig. 3. The transformation relationship is shown in the following equation (6):

the inverse transformation is Park inverse transformation or rotation inverse transformation, and is shown in the following formula (7):

and theta is an included angle between the d axis of the d-q rotating coordinate system and the alpha axis of the alpha-beta coordinate system, namely the d axis is an included angle with the axis of the A-phase winding.

That is, the three-phase A-B-C coordinate system of the stator and the d-q rotating coordinate system of the rotor have the following changing relationship:

the inverse transformation is as follows:

and theta is an included angle between the d axis of the d-q rotating coordinate system and the axis of the A-phase winding.

Through the analysis and the converted d-q coordinate system, a mathematical model of the permanent magnet synchronous motor under the d-q coordinate system can be determined.

The permanent magnet synchronous motor has a sinusoidal back electromotive force waveform, and the stator phase voltage and the phase current of the permanent magnet synchronous motor are also sinusoidal waveforms. Assuming that the motor is linear, the parameters do not change with temperature and the like, hysteresis loss and eddy current loss are ignored, and the rotor has no damping winding, the permanent magnet synchronous motor stator flux linkage equation in the rotor coordinate system (d-q coordinate system) is as follows:

ψ_d＝L_di_d+ψ_f (10)

ψ_q＝L_qi_q (11)

then the stator voltage equation of the permanent magnet synchronous motor is:

u_d＝Ri_d+Pψ_d-ωψ_f (12)

u_q＝Ri_q+Pψ_q+ωψ_f (13)

the torque equation of the permanent magnet synchronous motor is expressed by the following formula (14):

for a salient PMSM, L_d＝L_qSo that T_d＝P_nψ_fi_q。

In the above-described basic equation of the permanent magnet synchronous motor (d-q coordinate system), u_dFor the stator voltage of the straight axis u_qIs the quadrature stator voltage; i.e. i_dFor straight-axis stator currents, i_qIs quadrature axis stator current; l is_dIs a straight-axis stator inductance, L_qIs a quadrature axis stator inductance; psi_dFor a straight-axis stator flux linkage psi_qQuadrature axis stator flux linkage; r is a stator resistor; omega is the rotor speed of the motor, psi_fFor flux linkage produced by permanent magnets on the rotor, P being a differential operator, P_nThe number of pole pairs of the permanent magnet synchronous motor is shown.

As can be seen from the above formula, the electromagnetic torque of the permanent magnet synchronous motor basically depends on the quadrature-axis current component and the direct-axis current component of the stator. In the permanent magnet synchronous motor, because the rotor flux linkage is constant, the permanent magnet synchronous motor is controlled by adopting a rotor magnetic field orientation mode. After the permanent magnet synchronous motor adopts the directional control of the rotor magnetic field, the stator current vector is positioned on the quadrature axis, and no direct axis component exists, so that the voltage equation of the permanent magnet synchronous motor at the moment is as follows:

u_d＝-ωψ_q (15)

u_q＝Ri_q+Pψ_q+ωψ_d (16)

through the above analysis, it should be understood by those skilled in the art that, as long as the spatial position of the rotor can be accurately detected, that is, the inverter can be controlled to position the composite current (magnetomotive force) of the three-phase stator on the q-axis, the electromagnetic torque of the permanent magnet synchronous motor is only in proportion to the amplitude of the stator current, that is, the amplitude of the stator current is controlled, and the electromagnetic torque of the motor can be well controlled.

Based on the description of the corresponding embodiment shown in fig. 2 and the analysis of the vector control of the permanent magnet synchronous motor, in one embodiment, as shown in fig. 4, the motor operation parameter includes the stator phase current of the motor, and the determining the sliding mode variable value based on the motor operation parameter (i.e., step 220) includes the following steps:

step 410: and determining the coordinate axis measuring current of the motor under a rotating coordinate system according to the stator phase current of the motor.

Wherein, the coordinate axis measuring current in the rotating coordinate system comprises a direct axis measuring current (i.e. d-axis measuring current i)_d) And quadrature axis measuring current (i.e. q-axis measuring current i)_q)。

In a possible implementation manner, the implementation procedure of the above step 410 is: and converting the stator phase current of the motor into a coordinate axis measuring current under a static coordinate system through a first conversion function, and converting the coordinate axis measuring current under the static coordinate system into a coordinate axis measuring current under a rotating coordinate system through a second conversion function.

Wherein, the first change function is Clark conversion, and the stator three-phase current i can be converted through the Clark conversion_A、i_BAnd i_CConverted into equivalent measurement current i under two-phase static coordinate system_αAnd i_β(ii) a The second transformation function is Park transformation, and the equivalent measurement current i in the static coordinate system can be transformed through the Park transformation_αAnd i_βConversion into a rotating coordinate systemMeasuring current i of rotor_dAnd i_q。

Specifically, stator phase current i_A、i_BAnd i_CConverted into a measuring current i of the rotor_dAnd i_qThe process may refer to the above formula (4) and formula (6), or to the above formula (8), and will not be described herein again.

Step 420: determining a current error value according to the coordinate axis measuring current under the rotating coordinate system and the coordinate axis target current of the motor under the rotating coordinate system;

it should be noted that, referring to fig. 1, the coordinate axis target current in the rotating coordinate system is determined by the rotational speed controller 120 controlling the outer ring in the motor control system.

In a possible implementation process, the motor operating parameter includes a rotor speed of the motor, and the implementation process of determining the coordinate axis target current in the rotating coordinate system is as follows: and determining a rotation speed error value according to the rotor rotation speed of the motor and a preset target rotation speed, and acquiring coordinate axis target current of the motor in a rotation coordinate system according to a preset second control model and the rotation speed error value.

The current error value includes a direct-axis current error value between the direct-axis measurement current and the direct-axis target current, and a quadrature-axis current error value between the quadrature-axis measurement current and the quadrature-axis target current.

The second control model may be disposed in the rotation speed controller 120 shown in fig. 1, and the application does not limit the second control model, and the coordinate axis target current in the rotation coordinate system may be determined to be output under the condition that the rotation speed error value may be input again through the second control model.

In addition, the current vector control method of the permanent magnet synchronous motor is different according to different purposes, and the adopted control methods mainly comprise: i.e. i_dControl, power factor 0Control, constant flux linkage control, maximum torque/current control, flux weakening control and maximum outputPower control, etc. Different current control methods have different advantages i_dThe decoupling control of the PMSM is realized by the control of 0, and the PMSM is simplest and most common; power factorThe control reduces the capacity of the inverter matched with the control; the maximum output torque of the PMSM can be increased by the constant magnetic chain control; the maximum torque/current control can maximize the torque output per unit current; the PMSM is controlled by weak magnetism to operate at a higher rotating speed at constant power; the maximum output power is controlled to ensure that the maximum output power is the premise. For a convex PMSM i_d＝i_qThe rotor magnetic circuit is symmetrical, the reluctance torque is zero, and the maximum torque/current control is i_dControl is 0. i.e. i_dThe 0 control is most commonly applied in vector control of PMSM.

Based on the mathematical model of the permanent magnet synchronous motor in a d-q coordinate system, after the rotor magnetic field is adopted for directional control, the stator current vector is positioned on a q axis, and no d axis component exists. Therefore, when the sliding mode controller is designed based on PMSM vector control, the d-axis target current is set to be 0, and the q-axis target current is determined only through the second control model.

Step 430: and determining a sliding mode variable value according to the current error value and a preset current sliding mode surface function.

Wherein, the preset current sliding mode surface function may include: a direct-axis current sliding mode surface function and a quadrature-axis current sliding mode surface function. When sliding mode control is used, the measured current and the coordinate axis target current are required to be consistent.

In a possible implementation manner, a direct-axis current sliding mode surface function is designed according to the adjustment process of the direct-axis current (the process of making the error between the measured current and the target current approach to 0) by analyzing the adjustment process from the direct-axis measured current to the direct-axis target current, and similarly, an alternating-axis current sliding mode surface function is designed according to the adjustment process from the alternating-axis measured current to the alternating-axis target current by analyzing the adjustment process from the alternating-axis measured current to the alternating-axis target current.

As an example, the preset direct-axis current sliding mode surface function and quadrature-axis current sliding mode surface function are:

wherein S is_dFor variable values of straight-axis sliding forms, S_qThe variable value is the cross-axis sliding mode variable value; e.g. of the type_idError value of direct-axis current between direct-axis measured current and direct-axis target current, e_iqQuadrature current error value, lambda, between quadrature measured current and quadrature target current_d、λ_qAnd tau is an integral time variable for a control constant determined by the permanent magnet synchronous motor to be controlled according to needs.

And based on the formula, substituting the direct-axis current error value and the quadrature-axis current error value into a preset sliding mode surface function to obtain a direct-axis sliding mode variable value and a quadrature-axis sliding mode variable value.

In the embodiment of the application, the obtained stator phase current is converted by a coordinate system to obtain the corresponding measured current in a rotating coordinate system, and the sliding mode variable value is determined by the current error value between the measured current and the target current and the preset current sliding mode surface function. That is, a sliding mode surface function is designed by converting a current equation into a state equation according to an error between a measured current and a target current.

Based on the corresponding embodiment of fig. 4, in step 220 of the motor control method provided by the present application, it is further required to further determine the sliding mode surface based on the sliding mode variable value of step 430.

Specifically, the implementation process of determining the sliding mode surface based on the sliding mode variable value is as follows: and inputting the sliding mode variable value and the sliding mode coefficient into a preset system sliding mode surface function to obtain a sliding mode surface.

The application adopts a method that a continuous function approximates to a traditional switching function, provides a continuous fractional function, is used for replacing the switching function in the traditional sliding mode controller, and is used as a system sliding mode surface function of a motor control system, and the system sliding mode surface function is as follows:

wherein, sigma is a sliding mode coefficient, is a constant determined according to the controlled motor, and s is a sliding mode variable value. Specifically, the sliding mode variables include: the variable value S of the straight-axis sliding mode determined by the above formula (17)_dAnd a quadrature sliding mode variable value S determined by the above equation (18)_q。

In the embodiment of the application, based on a designed system sliding mode surface function, the sliding mode surface of the motor control system can be determined according to the variable value of the sliding mode. Therefore, when the sliding mode control method is used for outputting the voltage of the inverter, the response is fast, and the anti-jamming capability is strong.

Based on the embodiments corresponding to fig. 2 or fig. 4 described above, in one embodiment, the motor operating parameters include stator phase currents and rotor rotational speeds of the motor; the motor device attribute parameters comprise stator resistance, coordinate axis inductance under a rotating coordinate system and permanent magnet rotor flux linkage; the sliding mode variable value comprises a direct axis sliding mode variable value and an orthogonal axis sliding mode variable value; the slip form surface comprises a straight-axis slip form surface and a quadrature-axis slip form surface; the first control model comprises a direct-axis current control function and a quadrature-axis current control function; the target voltages include a direct-axis target voltage and a quadrature-axis target voltage. Referring to fig. 5, when the vector control is used to adjust the driving current and the torque of the synchronous permanent magnet motor, inputting the motor operation parameters, the motor device attribute parameters, the sliding mode variable values, and the sliding mode surfaces into a preset first control model to obtain the target voltage (i.e., step 230) includes the following steps:

step 510: and taking the direct-axis measured current, the quadrature-axis measured current, the rotor rotating speed, the stator resistance, the coordinate axis inductance, the direct-axis sliding mode variable and the direct-axis sliding mode surface under the rotating coordinate system as the input of a direct-axis current control function, and outputting a direct-axis target voltage through the direct-axis current control function.

As an example, the direct axis current control function may be the following equation (20):

step 520: and taking the direct-axis measurement current, the quadrature-axis measurement current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under a rotating coordinate system, the permanent magnet rotor flux linkage, the quadrature-axis sliding mode variable value and the quadrature-axis sliding mode surface as the input of a quadrature-axis current control function, and outputting a quadrature-axis target voltage through the quadrature-axis current control function.

As an example, the quadrature axis current control function may be the following equation (21):

in the above-mentioned formulas (20) and (21),is the target output voltage for the d-axis,a target output voltage for the q-axis; r is stator resistance, and omega is the actual rotating speed of the motor rotor; l is_dIs d-axis main inductance, L_qIs a q-axis main inductance; i.e. i_dIs d-axis current, i_qIs the q-axis current; k is a radical of_d0、k_ds、k_q0、k_qsA sliding mode control constant designed according to the performance of the controlled motor; psi_fPermanent magnet rotor flux linkage (flux linkage generated by permanent magnets on the rotor); s_dFor variable values of d-axis sliding modes, H(s)_d) A system sliding mode surface preset based on a d axis; s_qFor q-axis sliding mode variable values, H(s)_q) And the system sliding mode surface is preset based on the q axis.

Here, referring to the detailed description of the previous embodiment, the direct-axis measurement current and the quadrature-axis measurement current mentioned in the above steps 512 and 520 are determined according to the stator phase current of the motor. Specifically, the Clark transformation and Park transformation are performed to obtain the target signal, and are not described herein again.

It should be noted that, when the sliding mode controller is used for controlling the inner loop current, before the sliding mode controller is used for determining the output target voltage, it is also required to verify whether the designed sliding mode controller can determine the coordinate axis target voltage according to the motor operation parameters and the motor device attribute parameters.

As an example, to design a sliding mode controller with gradual stability, based on a d-q coordinate system, a sliding mode variable S is used_dAnd S_qThe lyapunov function for establishing the judgment stability is shown in the following formula (22):

wherein, v(s)_d,s_q) Denotes S_dAnd S_qConvergence to a speed from the equilibrium point (point where the error value of the measured current and the target current is 0), L_dIs d-axis main inductance, L_qIs a q-axis main inductance, S_dVariable for d-axis sliding mode, S_qThe variable value of the q-axis sliding mode is shown.

When S is_dAnd S_qAbove a certain threshold, the sliding mode controller will cause S_dAnd S_qThe control method has the advantages that the control method converges to a range which is small enough from a balance point, at the moment, the designed system sliding mode surface and the first control model meet the current control requirement of the controlled motor, and the driving voltage required by the controlled motor can be accurately estimated.

In the embodiment of the application, after the stability of the sliding mode controller is judged to meet the design requirement through the lyapunov function, the first control model can determine the target voltage for driving the motor according to the designed system sliding mode surface and the motor parameter. Therefore, the precision of sliding mode control is improved, the target voltage output by the first control model is more consistent with the driving voltage of the motor, and the torque output by the motor is more stable.

Based on the above-described embodiment, since the conversion of the coordinate system is involved in the vector control, the target voltages including the direct-axis target voltage and the quadrature-axis target voltage are obtained by the first control model. The inverter is a device for converting direct current into alternating current (generally, 220V, 50Hz sine wave), and therefore, after the target voltage is determined, pulse width modulation needs to be performed on the target voltage to obtain a switching signal of the inverter module, so as to control the switching tube of the inverter to be turned on and off.

As an example, the Pulse Width Modulation performed on the target voltage may employ a Space Vector Pulse Width Modulation (SVPWM) method. SVPWM takes the ideal flux linkage circle of the stator of a three-phase symmetrical motor as a reference standard when the three-phase symmetrical sine wave voltage is used for supplying power, and properly switches different switching modes of a three-phase inverter, so that a Pulse Width Modulation (PWM) wave is formed, and the accurate flux linkage circle is tracked by the formed actual flux linkage vector.

In one embodiment, after determining the target voltage through step 230, the motor control method provided by the present application further includes the following steps:

step 240: and converting the direct axis target voltage and the quadrature axis target voltage into coordinate axis target voltages under a static coordinate system through inverse transformation of the second transformation function.

Wherein the second transformation function is a Park transformation. The direct axis target voltage and the quadrature axis target voltage determined under the d-q coordinate system can be converted into coordinate axis target voltage under the alpha-beta coordinate system through Park inverse transformation.

As an example, the d-axis target output voltage determined based on the above equations (20) and (21) isq-axis target output voltage ofThe coordinate axis target voltage in the stationary coordinate system after Park inverse transformation can be expressed asA target output voltage of the alpha axis is represented,representing the target output voltage of the beta axis.

Step 250: and carrying out pulse width modulation on the coordinate axis target voltage under the static coordinate system to obtain a switching signal of the inverter module.

The switching signal is used for adjusting the output voltage of the inverter, and when the inverter supplies power to the motor by using the output voltage, the actual rotor rotating speed of the motor is the same as the preset target rotating speed.

Specifically, the SVPWM controls different switching modes of the inverter to switch properly, so that the actual magnetic flux generated by the motor approaches a standard magnetic flux circle, and a constant electromagnetic torque is generated, thereby achieving a better control performance.

In the embodiment of the application, the input voltage of the motor under a d-q coordinate systemAndcarrying out Park inverse transformation to obtain the input voltage of the motor under an alpha-beta coordinate systemAndwill be provided withAndand as a carrier signal, obtaining a switching tube control signal of the inverter through SVPWM, inputting the switching tube control signal of the inverter into a control circuit of the inverter, controlling the on and off of a switching device in the inverter, further outputting the three-phase input voltage of the motor, and driving the motor to operate according to a preset target rotating speed.

Based on the above description of the various embodiments, see fig. 6 and 7, and next, based on the vector control of the permanent magnet synchronous motor(i_d0), the motor control method of the present application is summarized.

Referring to fig. 6, the rotor speed ω and the stator phase current i of the PMSM are collected_A、i_BAnd i_CStator phase current i_A、i_BAnd i_CDirect-axis measuring current i converted into d-q rotating coordinate system through transformation function (Clark transformation and Park transformation)_dAnd quadrature axis measuring current i_q。

In the rotating speed control outer ring, the rotating speed omega of the rotor and the target rotating speed omega are adjusted^*The error value between the two is used as the input of a rotating speed controller, and the quadrature axis target current of the permanent magnet synchronous motor under a rotating coordinate system is determined by the rotating speed controller

In the current control inner ring, a direct-axis target current of the permanent magnet synchronous motor under a rotating coordinate system is setTarget current of straight axisAnd a direct axis measuring current i_dAs the input of the direct-axis current controller, the direct-axis input voltage of the permanent magnet synchronous motor under the d-q coordinate system is determined by the direct-axis current controller(target voltage); will intersect the axis of target currentAnd quadrature axis measuring current i_qAs the input of the quadrature axis current controller, determining the quadrature axis input voltage of the permanent magnet synchronous motor under the d-q coordinate system through the quadrature axis current controller(target voltage).

To the target voltageAndcarrying out Park inverse transformation to obtain the input voltage under an alpha-beta coordinate systemAndwill be provided withAndobtaining a switching signal of the inverter through SVPWM (space vector pulse width modulation) as a carrier signal, inputting the switching signal of the inverter into a control circuit of the inverter, controlling the on and off of a switching device in the inverter, further outputting a three-phase input voltage of the permanent magnet synchronous motor, and driving the permanent magnet synchronous motor to rotate at a preset target rotating speed omega^*And (5) operating.

The rotating speed controller can be a PID controller or a sliding mode controller, and in order to improve the control effect of the inner ring, the quadrature axis current controller and the direct axis current controller are both sliding mode controllers.

In a possible implementation manner, the rotation speed controller, the quadrature axis current controller, the direct axis current controller and the SVPWM algorithm may be integrated into one DSP controller for implementation, and a software program embedded in the DSP may call the corresponding functional unit, and the specific algorithm, etc. to work. The specific implementation flow refers to the following embodiment corresponding to fig. 7.

Referring to fig. 7, a motor control method provided in an embodiment of the present application includes:

step 701: and acquiring motor operation parameters and motor device attribute parameters.

The motor operation parameters comprise stator phase current and rotor rotating speed of the motor, and the motor device attribute parameters comprise stator resistance, coordinate axis inductance and permanent magnet rotor flux linkage under a rotating coordinate system.

Step 702: and determining a rotation speed error value according to the rotor rotation speed of the motor and a preset target rotation speed.

Step 703: and obtaining the coordinate axis target current of the motor in the rotating coordinate system according to a preset second control model and the rotating speed error value.

The coordinate axis target current of the motor in the rotating coordinate system comprises d-axis target current and q-axis target current, and i is adopted in the method_dSince the vector control method is 0, the direct axis target current is set to 0.

Step 704: and converting the stator phase current of the motor into coordinate axis measuring current under a static coordinate system through a first conversion function.

The static coordinate system is an alpha-beta coordinate system, the first transformation function is Clark transformation, and the coordinate axis measurement current in the static coordinate system comprises alpha-axis stator current and beta-axis stator current.

Step 705: and converting the coordinate axis measuring current in the static coordinate system into the coordinate axis measuring current in the rotating coordinate system through a second transformation function.

The rotating coordinate system is a d-q coordinate system, the second transformation function is Park transformation, and the coordinate axis measuring current in the rotating coordinate system comprises d-axis measuring current and q-axis measuring current.

Step 706: and determining a current error value according to the coordinate axis measuring current in the rotating coordinate system and the coordinate axis target current of the motor in the rotating coordinate system.

Since the coordinate axis measurement current in the rotating coordinate system includes the d-axis measurement current and the q-axis measurement current, and the coordinate axis target current in the rotating coordinate system includes the d-axis target current and the q-axis target current, the current error value may be a d-axis current error value and a q-axis current error value.

Step 707: determining a sliding mode variable value according to the current error value and a preset current sliding mode surface function;

the preset current sliding mode surface function comprises a d-axis current sliding mode surface function and a q-axis current sliding mode surface function, and the determined sliding mode variable value comprises a d-axis sliding mode variable and a q-axis sliding mode variable value.

Step 708: and inputting the sliding mode variable value and the sliding mode coefficient into a preset system sliding mode surface function to obtain a sliding mode surface.

The sliding mode surface comprises a d-axis sliding mode surface and a q-axis sliding mode surface.

Step 709: and taking the direct-axis measured current, the quadrature-axis measured current, the rotor rotating speed, the stator resistance, the coordinate axis inductance, the direct-axis sliding mode variable and the direct-axis sliding mode surface under the rotating coordinate system as the input of a direct-axis current control function, and outputting a direct-axis target voltage through the direct-axis current control function.

Step 710: and taking the direct-axis measurement current, the quadrature-axis measurement current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under a rotating coordinate system, the permanent magnet rotor flux linkage, the quadrature-axis sliding mode variable value and the quadrature-axis sliding mode surface as the input of a quadrature-axis current control function, and outputting a quadrature-axis target voltage through the quadrature-axis current control function.

Step 711: and converting the direct axis target voltage and the quadrature axis target voltage into coordinate axis target voltages under a static coordinate system through inverse transformation of the second transformation function.

And the inverse transformation of the second transformation function is inverse Park transformation, and the d-axis target voltage and the q-axis target voltage are transformed into alpha-axis target voltage and beta-axis target voltage.

Step 712: and carrying out pulse width modulation on the coordinate axis target voltage under the static coordinate system to obtain a switching signal of the inverter module.

Specifically, the α -axis target voltage and the β -axis target voltage are used as carrier signals, and switching signals of the inverter are obtained by SVPWM.

It should be noted that, for the detailed description of the above specific embodiments, reference is made to the foregoing text, and no further description is provided herein.

In the embodiment of the application, the sliding mode controller designed according to the motor parameters to be controlled can output the target voltage of the driving motor under the condition of inputting the motor operation parameters and the motor device attribute parameters. In this way, when the output voltage of the inverter is the target voltage, the nonlinear distortion voltage output by the inverter can be eliminated, and when the inverter drives the motor based on the target voltage, the motor can be made to output a stable torque.

It should be understood that, although the steps in the method flow chart corresponding to the above-described embodiment are sequentially displayed as indicated by the arrow, the steps are not necessarily sequentially executed as indicated by the arrow. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a part of the steps in the method flowcharts corresponding to the above embodiments may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of performing the steps or stages is not necessarily sequential, but may be performed alternately or alternately with other steps or at least a part of the steps or stages in other steps.

Referring to fig. 8, the present application further provides a motor control apparatus, wherein the motor control apparatus 800 may be configured in the current control module 130 in the implementation environment shown in fig. 1. As shown in fig. 8, the robot calibration apparatus 800 may include an acquisition module 810, a determination module 820, and a control module 830, wherein:

an obtaining module 810, configured to obtain a motor operation parameter and a motor device attribute parameter;

a determining module 820 for determining a sliding mode variable value based on the motor operating parameter and determining a sliding mode surface based on the sliding mode variable value;

the control module 830 is configured to input the motor operation parameter, the motor device attribute parameter, the sliding mode variable value, and the sliding mode surface into a preset first control model to obtain a target voltage; the target voltage regulates an output voltage of the inverter, and the output voltage is a supply voltage of the motor.

In one embodiment, the motor operating parameter comprises a stator phase current of the motor;

a determining module 820 comprising:

the first determining subunit is used for determining coordinate axis measuring current of the motor in a rotating coordinate system according to the stator phase current of the motor;

the second determining subunit is used for determining a current error value according to the coordinate axis measuring current in the rotating coordinate system and the coordinate axis target current of the motor in the rotating coordinate system;

and the third determining subunit is used for determining the sliding mode variable value according to the current error value and a preset current sliding mode surface function.

In one embodiment, the coordinate axis measurement current comprises a direct axis measurement current and a quadrature axis measurement current; the coordinate axis target current comprises a direct axis target current and a quadrature axis target current;

the current error values include a direct-axis current error value between the direct-axis measured current and the direct-axis target current, and a quadrature-axis current error value between the quadrature-axis measured current and the quadrature-axis target current.

In one embodiment, the first determining subunit is specifically configured to:

converting the stator phase current of the motor into coordinate axis measuring current under a static coordinate system through a first transformation function;

and converting the coordinate axis measuring current in the static coordinate system into the coordinate axis measuring current in the rotating coordinate system through a second transformation function.

In one embodiment, the motor operating parameter comprises a rotor speed of the motor;

before determining a current error value based on the coordinate axis measured current and a coordinate axis target current of the motor in the rotating coordinate system, the motor apparatus 800 is further configured to:

determining a rotation speed error value according to the rotor rotation speed of the motor and a preset target rotation speed;

and obtaining the coordinate axis target current of the motor in the rotating coordinate system according to a preset second control model and the rotating speed error value.

In one embodiment, the determining module 820 further comprises:

and the fourth determining subunit is used for inputting the sliding mode variable value and the sliding mode coefficient into a preset system sliding mode surface function to obtain a sliding mode surface.

In one embodiment, the motor operating parameters include a stator phase current and a rotor speed of the motor; the motor device attribute parameters comprise stator resistance, coordinate axis inductance under a rotating coordinate system and permanent magnet rotor flux linkage; the sliding mode variable value comprises a direct axis sliding mode variable value and an orthogonal axis sliding mode variable value; the slip form surface comprises a straight-axis slip form surface and a quadrature-axis slip form surface; the first control model comprises a direct-axis current control function and a quadrature-axis current control function; the target voltage comprises a direct-axis target voltage and a quadrature-axis target voltage;

accordingly, the control module 830 includes:

the direct-axis control subunit is used for taking the direct-axis measured current, the quadrature-axis measured current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under a rotating coordinate system, the direct-axis sliding mode variable and the direct-axis sliding mode surface as the input of a direct-axis current control function and outputting a direct-axis target voltage through the direct-axis current control function; the direct-axis measuring current and the quadrature-axis measuring current are determined according to the stator phase current of the motor;

and the quadrature axis control subunit is used for taking the direct axis measurement current, the quadrature axis measurement current, the rotor rotating speed, the stator resistance, the coordinate axis inductance under a rotating coordinate system, the permanent magnet rotor flux linkage, the quadrature axis sliding mode variable value and the quadrature axis sliding mode surface as the input of the quadrature axis current control function, and outputting the quadrature axis target voltage through the quadrature axis current control function.

In one embodiment, the motor control apparatus 800 is further configured to:

converting the direct axis target voltage and the quadrature axis target voltage into coordinate axis target voltage under a static coordinate system through inverse transformation of a second transformation function;

performing pulse width modulation on a coordinate axis target voltage under a static coordinate system to obtain a switching signal of the inverter module; the switching signal is used for adjusting the output voltage of the inverter, and when the inverter supplies power to the motor by using the output voltage, the actual rotor rotating speed of the motor is the same as the preset target rotating speed.

In the embodiment of the application, a motor control device acquires motor operation parameters and motor device attribute parameters; determining a sliding mode variable value based on the motor operation parameters, and determining a sliding mode surface based on the sliding mode variable value; inputting motor operation parameters, motor device attribute parameters, sliding mode variable values and sliding mode surfaces into a preset first control model to obtain target voltage; the target voltage regulates an output voltage of the inverter, and the output voltage is a supply voltage of the motor. That is, in the motor control process, the sliding mode controller designed according to the parameters of the motor to be controlled can output the target voltage of the driving motor under the condition of inputting the motor operation parameters and the motor device attribute parameters. In this way, when the output voltage of the inverter is the target voltage, the nonlinear distortion voltage output by the inverter can be eliminated, and when the inverter drives the motor based on the target voltage, the motor can be made to output a stable torque.

In the motor control device provided in the above embodiment, when controlling the driving current of the motor, only the division of the above functional modules is taken as an example, and in practical applications, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the above described functions. In addition, each module in the above-described motor control device may be entirely or partially implemented by software, hardware, or a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.

It can be understood that the motor control device and the motor control method provided by the above embodiments belong to the same concept, and the specific implementation process thereof is detailed in the above stable motor control method embodiment, and is not described again here.

In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as shown in fig. 9. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected by a system bus. The memory stores a computer program, and the processor implements all or part of the flow in the motor control method embodiment when executing the computer program.

In particular, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used for carrying out wired or wireless communication with an external terminal, and the wireless communication can be realized through WIFI, an operator network, NFC (near field communication) or other technologies. The computer program is executed by a processor to implement a motor control method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.

Any reference to memory, storage, database, or other medium used in various embodiments of the motor control methods provided herein may include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.

Those skilled in the art will appreciate that the architecture shown in fig. 9 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.

In an embodiment of the present application, a computer-readable storage medium is provided, on which a computer program is stored, which, when being executed by a processor, implements the flow of the above-mentioned respective motor control method embodiments.

Specifically, all or part of the flow of the motor control method embodiments may be implemented by a computer program that may be stored in a non-volatile computer-readable storage medium and that, when executed, may include the flow of the motor control method embodiments.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.