Permanent magnet synchronous motor control method and system

Abstract

The invention relates to the technical field of motor control, and particularly provides a permanent magnet synchronous motor control method and system, and the method comprises the steps: building an expansion state model according to a mechanical motion equation of a permanent magnet synchronous motor; designing a nonlinear extended state observer based on the extended state model, and estimating total interference in real time; based on the total interference, an error feedback control law is designed, interference is compensated, and a q-axis current reference value is generated; according to the invention, the precise reconstruction of the back electromotive force and the extraction of the position speed are realized, the position estimation precision is improved, and the high-performance permanent magnet synchronous motor control is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and specifically provides a permanent magnet synchronous motor control method and system. Background Art

[0002] Permanent magnet synchronous motors have been widely used in ship propulsion, railway traction systems, wind power generation and other fields due to their high reliability, high power density and low vibration. In the vector control framework, permanent magnet synchronous motors usually require an encoder to obtain the rotor position. However, in extreme environments with rapid changes in temperature and humidity, the encoder may fail. Therefore, in order to improve the operating reliability and stability of permanent magnet synchronous motors, position sensorless control is a control method with great development potential.

[0003] For permanent magnet synchronous motors running at medium and high speeds, the position and speed extraction scheme based on back-EMF has attracted wide attention from academia and industry due to its simple design and easy application. An observer is usually used to estimate the back-EMF, and a phase-locked loop is used to extract the position and speed. However, the traditional sliding mode observer has jitter and cannot converge in a finite time, and the traditional phase-locked loop cannot handle the position estimation error during speed ramp acceleration and deceleration, which affects the position estimation accuracy of position sensorless control.

[0004] Therefore, in order to solve the above problems, the present application proposes a permanent magnet synchronous motor control method and system. Summary of the invention

[0005] Aiming at the position estimation error of sensors in traditional methods, the present invention provides a permanent magnet synchronous motor control method and system to achieve high-performance permanent magnet synchronous motor control.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: In a first aspect, the present application provides a permanent magnet synchronous motor control method, comprising: According to the mechanical motion equation of the permanent magnet synchronous motor, an expansion state model is established; Based on the extended state model, a nonlinear extended state observer is designed to estimate the total interference in real time; Based on the total disturbance, an error feedback control law is designed to compensate for the disturbance and generate a q-axis current reference value.

[0007] Furthermore, the step of establishing the extended state model according to the mechanical motion equation of the permanent magnet synchronous motor specifically includes the following steps: The mechanical motion equation is expressed as: (1), in, is the motor moment of inertia; is the motor mechanical angular velocity; is the motor mechanical angular velocity The derivative of is the viscous friction coefficient; is the electromagnetic torque; is the load torque; In a surface mounted permanent magnet synchronous motor, the electromagnetic torque It is expressed as: (2), in, is the number of motor pole pairs; is the permanent magnet flux; for q Shaft measuring current; represents the electromagnetic torque coefficient; According to equations (1) and (2), the mechanical motion equation is updated as follows: (3), in, is the nominal value of the control system gain, is the nominal value of the permanent magnet flux, is the nominal value of the moment of inertia; is the q-axis current reference value; is the total disturbance within the velocity loop system, including but not limited to internal parameter perturbations, external load changes, and unknown or unmodeled dynamics.

[0008] Furthermore, the total interference It is expressed as: (4), According to equations (3) and (4), the expansion state model is: (5), in, Total interference The derivative of is the differential term of the total disturbance.

[0009] Furthermore, the step of designing a nonlinear extended state observer based on the extended state model to estimate the total interference in real time specifically includes the following steps: Design of nonlinear fast-converging functions , expressed as: (6), in, is the mechanical angular velocity estimation error, is the estimated mechanical angular velocity; , and is the parameter of the convergence function, , , ; is a constant; is a symbolic function; It is expressed as: (7).

[0010] Furthermore, according to equations (5) and (6), the nonlinear extended state observer is expressed as: (8), in, is the estimated total interference, and are the gain parameters of the nonlinear extended state observer respectively.

[0011] Furthermore, the step of designing an error feedback control law based on the total disturbance, compensating for the disturbance and generating a q-axis current reference value specifically includes the following steps: According to the difference between the reference mechanical angular velocity command and the feedback mechanical angular velocity, an error signal is constructed , expressed as:

[0012] in, For reference to the mechanical angular velocity command, is the motor mechanical angular velocity; The first-order differential of is: (9), Based on the error feedback control strategy, the error proportional feedback is obtained as follows: (10), in, is the control gain of the speed loop.

[0013] Furthermore, substituting formula (10) into formula (9), we obtain: (11), The nonlinear extended state observer estimates and Substituting into equation (11), the error feedback control law is: (12).

[0014] In a second aspect, the present application provides a permanent magnet synchronous motor control system, comprising: Model building module: Establish an extended state model based on the mechanical motion equation of the permanent magnet synchronous motor; Observer module: Based on the extended state model, a nonlinear extended state observer is designed to estimate the total interference in real time; Control law module: Based on the total disturbance, an error feedback control law is designed to compensate for the disturbance and generate a q-axis current reference.

[0015] Compared with the prior art, the invention can achieve the following beneficial effects: (1) By constructing the mechanical motion equation of the permanent magnet synchronous motor, the system dynamics is expanded into a second-order model including the total disturbance, namely the extended state model. The extended state model explicitly incorporates the uncertain disturbance into the state equation, providing a mathematical basis for the subsequent observer design and enabling the system to adapt to parameter mismatch. At the same time, the nonlinear disturbance is linearized, reducing the complexity of the control law design. (2) The traditional sliding mode observer causes high-frequency jitter due to the switching function. The nonlinear function proposed in this application reduces the jitter amplitude through the continuous and smooth convergence characteristics. The nonlinear extended state observer constructed based on this function optimizes the dynamic performance of the disturbance estimation through the gain parameter, implements tracking of time-varying interference, and provides reliable input for subsequent compensation. (3) This application designs an error feedback control rate based on the output of the nonlinear extended state observer, and feeds forward the total disturbance to the current command. The traditional phase-locked loop causes position error due to integral lag, and this application reduces the error through the error feedback control rate. Therefore, the accuracy, robustness and dynamic performance of the permanent magnet synchronous motor under position sensorless control are significantly improved, providing an efficient solution for the field of industrial high-precision drives. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 is a flow chart of a permanent magnet synchronous motor control method according to Embodiment 1; Figure 2 is a control block diagram of a permanent magnet synchronous motor control method of this embodiment 1; Figure 3 is a structural block diagram of a permanent magnet synchronous motor control method of this embodiment 1; Figure 4 Schematic diagram of the structure of a permanent magnet synchronous motor control system according to the second embodiment. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and do not constitute a limitation to the invention. Similar components in different embodiments use associated similar component numbers. In the following embodiments, many detailed descriptions are to enable the invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other components, materials, and methods. In some cases, some operations related to the invention are not shown or described in the specification, in order to avoid the core part of the invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0018] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0020] Example 1 See also Figure 1 , is a flow chart of a permanent magnet synchronous motor control method according to this embodiment; the specific steps include: S1: Establish an extended state model based on the mechanical motion equations of the permanent magnet synchronous motor.

[0021] In this embodiment, the mechanical motion equation is expressed as: (1), in, is the motor moment of inertia; is the motor mechanical angular velocity; is the motor mechanical angular velocity The derivative of is the viscous friction coefficient; is the electromagnetic torque; is the load torque.

[0022] In a surface mounted permanent magnet synchronous motor, the electromagnetic torque It is expressed as: (2), in, is the number of motor pole pairs; is the permanent magnet flux; for q Shaft measuring current; Represents the electromagnetic torque coefficient.

[0023] According to equations (1) and (2), the mechanical motion equation is updated as follows: (3), in, is the nominal value of the control system gain, is the nominal value of the permanent magnet flux, is the nominal value of the moment of inertia; is the q-axis current reference value; is the total disturbance within the velocity loop system, including but not limited to internal parameter perturbations, external load changes, and unknown or unmodeled dynamics.

[0024] The total interference It is expressed as: (4), According to equations (3) and (4), the expansion state model is: (5), in, Total interference The derivative of is the differential term of the total disturbance.

[0025] S2: Based on the extended state model, a nonlinear extended state observer is designed to estimate the total interference in real time.

[0026] In this embodiment, based on step S1, a new nonlinear fast convergence function and a nonlinear extended state observer based on the function are designed to quickly estimate the disturbance in the motor system in real time. The traditional nonlinear convergence function is piecewise and the convergence speed is limited. In order to speed up the convergence speed, a new nonlinear fast convergence function is designed. , expressed as: (6), in, is the mechanical angular velocity estimation error, is the estimated mechanical angular velocity; , and is the parameter of the convergence function, , , ; is a constant; is a symbolic function; It is expressed as: (7).

[0027] According to equations (5) and (6), the nonlinear extended state observer is expressed as: (8), in, is the estimated total interference, and are the gain parameters of the nonlinear extended state observer respectively.

[0028] S3: Based on the total disturbance, an error feedback control law is designed to compensate for the disturbance and generate a q-axis current reference value.

[0029] In this embodiment, after the disturbance is accurately estimated, an error feedback control law is designed for disturbance compensation. The error signal is constructed based on the difference between the reference mechanical angular velocity command and the feedback mechanical angular velocity. , expressed as:

[0030] in, For reference to the mechanical angular velocity command, is the motor mechanical angular velocity; The first-order differential of is: (9), Based on the error feedback control strategy, the error proportional feedback is obtained as follows: (10), in, is the control gain of the speed loop.

[0031] Substituting formula (10) into formula (9), we get: (11), The nonlinear extended state observer estimates and Substituting into equation (11), the error feedback control law is: (12).

[0032] In this way, the estimation and compensation of disturbances are achieved.

[0033] Specifically, a surface-mounted permanent magnet synchronous motor is selected, and its parameters are as follows: Nominal value of moment of inertia ; Nominal value of permanent magnet flux ; Number of motor pole pairs ; Viscous friction coefficient ; Load torque It changes dynamically according to the actual working conditions, ranging from 0 to 10.

[0034] Mechanical motion equation is established: According to equations (1) and (2), the electromagnetic torque coefficient for:

[0035] The mechanical motion equation is transformed into equation (3):

[0036] Total interference Calculated according to formula (4), including parameter perturbations, load changes and unmodeled dynamics.

[0037] According to equations (3) and (4), the expansion state model is expressed as:

[0038] Set the parameters of the nonlinear fast convergence function to: , enhance the convergence speed when the error is large; , optimize the smoothness of small error regions; , adjust the overall convergence strength; , which is used to suppress parameter sensitivity.

[0039] Then the nonlinear fast convergence function (6) is expressed as:

[0040] Determine the observer gain through Lyapunov stability analysis , , nonlinear extended state observer (8):

[0041] Build an observer model in Matlab / Simulink and set the initial velocity error , total interference The simulation results show that the observer converges the error to within 0.1 rad / s within 0.05 s, and the jitter amplitude is less than 20% of the traditional sliding mode observer.

[0042] Design error feedback control law: Set the control gain of the speed loop , ensuring the dynamic response bandwidth is 100Hz. According to formula (12), the q-axis current reference value is:

[0043] Set the reference mechanical angular velocity command by The acceleration from Rise to The experimental results show that the position error of the conventional phase-locked loop in the acceleration section is as high as 2%, while the position compensation phase-locked loop of the present invention reduces the error to 0.3% without overshoot.

[0044] Therefore, the present invention solves the defects of the traditional method in terms of jitter, convergence speed and dynamic error through a novel nonlinear observer and a compensating phase-locked loop. The embodiment shows that its position estimation accuracy and anti-interference ability are improved, and it is suitable for industrial scenarios with high dynamics and strong interference.

[0045] See also Figure 2 , which is a control block diagram of a permanent magnet synchronous motor control method of this embodiment 1. It includes a nonlinear extended state observer, an error feedback control law and a motor body. The nonlinear extended state observer is used to observe the internal and external disturbances and unmodeled dynamics of the speed loop, and the error feedback control law is used to compensate for the observed disturbance. and Directly input the controller to achieve closed-loop disturbance rejection.

[0046] See also Figure 3 , is a structural block diagram of a permanent magnet synchronous motor control method of this embodiment 1. The transmission paths of various signals and the interaction relationships between modules are marked.

[0047] In summary, this embodiment 1 first constructs the mechanical motion equation of the permanent magnet synchronous motor and establishes an extended state mathematical model; secondly, a new nonlinear fast convergence function and a nonlinear extended state observer are designed to quickly and in real time estimate the disturbance in the motor system; finally, after the disturbance is accurately estimated, an error feedback control law is designed for disturbance compensation. This application improves the position estimation accuracy, realizes the accurate reconstruction of the back electromotive force and the extraction of the position and speed, thereby improving the control performance of the permanent magnet synchronous motor.

[0048] Example 2 See also Figure 4 , is a structural diagram of a permanent magnet synchronous motor control system described in this embodiment; the specific contents include: Model building module: Establish an extended state model based on the mechanical motion equations of the permanent magnet synchronous motor.

[0049] Observer module: Based on the extended state model, a nonlinear extended state observer is designed to estimate the total interference in real time.

[0050] Control law module: Based on the total disturbance, an error feedback control law is designed to compensate for the disturbance and generate a q-axis current reference.

[0051] In this embodiment, an extended state model is obtained through a model building module, and an observer module uses the extended state model to design a nonlinear extended state observer to estimate the total disturbance in the system in real time. The control law module designs an error feedback control law based on the estimated total disturbance to compensate for the disturbance and generate a q-axis current reference. The proposed control system can realize rapid and accurate estimation and compensation of disturbances in a permanent magnet synchronous motor system, thereby improving the control performance and operation stability of the motor.

[0052] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0053] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A permanent magnet synchronous motor control method, characterized in that: include: According to the mechanical motion equation of the permanent magnet synchronous motor, an expansion state model is established; Based on the extended state model, a nonlinear extended state observer is designed to estimate the total interference in real time; Based on the total disturbance, an error feedback control law is designed to compensate for the disturbance and generate a q-axis current reference value.

2. A permanent magnet synchronous motor control method according to claim 1, characterized in that: The step of establishing the extended state model according to the mechanical motion equation of the permanent magnet synchronous motor specifically includes the following steps: The mechanical motion equation is expressed as: （1）， in, is the motor moment of inertia; is the motor mechanical angular velocity; is the motor mechanical angular velocity The derivative of is the viscous friction coefficient; is the electromagnetic torque; is the load torque; In a surface mounted permanent magnet synchronous motor, the electromagnetic torque It is expressed as: （2）， in, is the number of motor pole pairs; is the permanent magnet flux; for q Shaft measuring current; represents the electromagnetic torque coefficient; According to equations (1) and (2), the mechanical motion equation is updated as follows: （3）， in, is the nominal value of the control system gain, is the nominal value of the permanent magnet flux, is the nominal value of the moment of inertia; is the q-axis current reference value; is the total disturbance within the velocity loop system, including but not limited to internal parameter perturbations, external load changes, and unknown or unmodeled dynamics.

3. A permanent magnet synchronous motor control method according to claim 2, characterized in that: The total interference It is expressed as: （4）， According to equations (3) and (4), the expansion state model is: （5）， in, Total interference The derivative of is the differential term of the total disturbance.

4. A permanent magnet synchronous motor control method according to claim 3, characterized in that: The step of designing a nonlinear extended state observer based on the extended state model to estimate the total interference in real time specifically includes the following steps: Design nonlinear fast-converging functions , expressed as: （6）， in, is the mechanical angular velocity estimation error, is the estimated mechanical angular velocity; , and is the parameter of the convergence function, , , ; is a constant; is a symbolic function; It is expressed as: （7）。 5. A permanent magnet synchronous motor control method according to claim 4, characterized in that: According to equations (5) and (6), the nonlinear extended state observer is expressed as: （8）， in, is the estimated total interference, and are the gain parameters of the nonlinear extended state observer respectively.

6. A permanent magnet synchronous motor control method according to claim 5, characterized in that: The step of designing an error feedback control law based on the total disturbance, compensating for the disturbance and generating a q-axis current reference value specifically includes the following steps: According to the difference between the reference mechanical angular velocity command and the feedback mechanical angular velocity, an error signal is constructed , expressed as: in, For reference to the mechanical angular velocity command, is the motor mechanical angular velocity; The first-order differential of is: （9）， Based on the error feedback control strategy, the error proportional feedback is obtained as follows: （10）， in, is the control gain of the speed loop.

7. A permanent magnet synchronous motor control method according to claim 6, characterized in that: Substituting formula (10) into formula (9), we get: （11）， The nonlinear extended state observer estimates and Substituting into equation (11), the error feedback control law is: （12）。 8. A permanent magnet synchronous motor control system, characterized in that: include: Model building module: Establish an extended state model based on the mechanical motion equation of the permanent magnet synchronous motor; Observer module: Based on the extended state model, a nonlinear extended state observer is designed to estimate the total interference in real time; Control law module: Based on the total disturbance, an error feedback control law is designed to compensate for the disturbance and generate a q-axis current reference value.

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