A Permanent Magnet Synchronous Motor Control Method and System

Abstract

The present invention relates to the technical field of motor control, and specifically provides a permanent magnet synchronous motor control method and system. The steps include: establishing an extended state model according to the mechanical motion equation of the permanent magnet synchronous motor; designing a nonlinear extended state observer based on the extended state model to estimate the total disturbance in real time; designing an error feedback control law based on the total disturbance to compensate for the disturbance and generate a q-axis current reference value; realizing accurate reconstruction of the back electromotive force and extraction of the position and speed through the present application, improving the position estimation accuracy, and realizing high-performance permanent magnet synchronous motor control.

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] Due to its characteristics such as high reliability, high power density, and low vibration, permanent magnet synchronous motors have been widely used in fields such as ship propulsion, railway traction systems, and wind power generation. In the vector control framework, a permanent magnet synchronous motor usually requires 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, sensorless control is a very promising control method.

[0003] For permanent magnet synchronous motors operating at medium and high speeds, the back-electromotive force-based position and speed extraction scheme has received extensive attention in the academic and industrial fields due to its simple design and easy application. An observer is usually used to estimate the back-electromotive force, and a phase-locked loop is used to achieve the extraction of position and speed. However, the traditional sliding mode observer has chattering 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 sensorless control.

[0004] Therefore, 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 the sensors in the traditional method, 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 of the present invention is realized as follows:

[0007] In a first aspect, the present application provides a permanent magnet synchronous motor control method, including:

[0008] Establish an extended state model according to the mechanical motion equation of the permanent magnet synchronous motor;

[0009] Based on the extended state model, design a nonlinear extended state observer to estimate the total disturbance in real time;

[0010] Based on the total disturbance, design an error feedback control law to compensate for the disturbance and generate a q-axis current reference value.

[0011] Further, in the step of establishing an extended state model according to the mechanical motion equation of the permanent magnet synchronous motor, the following steps are specifically included:

[0012] The mechanical motion equation is expressed as:

[0013] (1),

[0014] wherein, is the moment of inertia of the motor; is the mechanical angular velocity of the motor; is the mechanical angular velocity of the derivative; is the viscous friction coefficient; is the electromagnetic torque; is the load torque;

[0015] In the surface-mounted permanent magnet synchronous motor, the electromagnetic torque is expressed as:

[0016] (2),

[0017] wherein, is the number of pole pairs of the motor; is the permanent magnet flux linkage; is q the measured current on the q-axis; Let represent the electromagnetic torque coefficient;

[0018] According to equations (1) and (2), the mechanical motion equation is updated to:

[0019] (3),

[0020] wherein, is the nominal value of the control system gain, is the nominal value of the permanent magnet flux linkage, is the nominal value of the moment of inertia; is the q-axis current reference value; is the total disturbance within the speed loop system, including but not limited to internal parameter perturbations, external load variations, and unknown or unmodeled dynamics.

[0021] Furthermore, the total disturbance is expressed as:

[0022] (4),

[0023] From equations (3) and (4), the extended state model is:

[0024] (5),

[0025] wherein, is the derivative of the total disturbance ; is the differential term of the total disturbance.

[0026] Furthermore, in the step of designing a non-linear extended state observer based on the extended state model to estimate the total disturbance in real time, the following specific steps are included:

[0027] Design a non-linear fast convergence function , expressed as:

[0028] (6),

[0029] where, is the estimated error of the mechanical angular velocity, is the estimated mechanical angular velocity; , and are the parameters of the convergence function, , , ; is a constant; is the sign function;

[0030] is expressed as:

[0031] (7).

[0032] Furthermore, according to equations (5) and (6), the non-linear extended state observer is expressed as:

[0033] (8),

[0034] where, is the estimated total disturbance, and are the gain parameters of the non-linear extended state observer, respectively.

[0035] Furthermore, in the step of designing an error feedback control law based on the total disturbance to compensate for the disturbance and generate the q-axis current reference value, the following specific steps are included:

[0036] Construct an error signal according to the difference between the reference mechanical angular velocity command and the feedback mechanical angular velocity, expressed as:

[0037]

[0038] where, is the reference mechanical angular velocity command, is the motor mechanical angular velocity;

[0039] The first derivative of

[0040] (9),

[0041] Based on the error feedback control strategy, the error proportional feedback is obtained as

[0042] (10),

[0043] where is the control gain of the speed loop.

[0044] Further, substituting Equation (10) into Equation (9), we get:

[0045] (11),

[0046] Substituting the and estimated by the non - linear extended state observer into Equation (11), the error feedback control law is:

[0047] (12).

[0048] In a second aspect, the present application provides a permanent magnet synchronous motor control system, including:

[0049] Model construction module: Establish an extended state model according to the mechanical motion equation of the permanent magnet synchronous motor.

[0050] Observer module: Based on the extended state model, design a non - linear extended state observer to estimate the total disturbance in real - time.

[0051] Control law module: Based on the total disturbance, design an error feedback control law to compensate for the disturbance and generate the q - axis current reference.

[0052] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0053] (1) By constructing the mechanical motion equation of the permanent magnet synchronous motor, the system dynamics is extended to a second - order model including the total disturbance, that is, 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, enabling the system to have an adaptive ability to parameter mismatch; at the same time, linearizing the non - linear disturbance reduces the complexity of the control law design.

[0054] (2) The traditional sliding - mode observer causes high - frequency chattering due to the switching function. The non - linear function proposed in this application reduces the chattering amplitude through continuous and smooth convergence characteristics; the non - linear extended state observer constructed based on this function optimizes the dynamic performance of the disturbance estimation through the gain parameter, implements the tracking of time - varying disturbances, and provides a reliable input for subsequent compensation.

[0055] (3) Based on the output of the non-linear extended state observer, this application designs an error feedback control law to feed forward and compensate for the total disturbance to the current command. Due to the integral lag of the traditional phase-locked loop, position errors occur. This application reduces the errors through the error feedback control law, thus significantly improving the accuracy, robustness, and dynamic performance of the permanent magnet synchronous motor under sensorless control, and providing an efficient solution for the field of industrial high-precision drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0057] Figure 1 It is a schematic flowchart of a control method for a permanent magnet synchronous motor in Embodiment 1;

[0058] Figure 2 It is a control block diagram of a control method for a permanent magnet synchronous motor in Embodiment 1;

[0059] Figure 3 It is a structural block diagram of a control method for a permanent magnet synchronous motor in Embodiment 1;

[0060] Figure 4 It is a schematic structural diagram of a control system for a permanent magnet synchronous motor in Embodiment 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments are labeled with related similar element numbers. In the following embodiments, many details are described to enable a better understanding of the present invention. 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 elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification to avoid the core part of the present invention being overwhelmed by excessive description. 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 based on the description in the specification and the general technical knowledge in the field.

[0062] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other to form various implementation manners. At the same time, the steps or actions in the method description can also be adjusted or reordered in an obvious manner by those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0063] The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0064] Embodiment 1

[0065] Please refer to Figure 1 , which is a schematic flow diagram of a permanent magnet synchronous motor control method according to this embodiment; the specific steps include:

[0066] S1: Establish an extended state model according to the mechanical motion equation of the permanent magnet synchronous motor.

[0067] In this embodiment, the mechanical motion equation is expressed as:

[0068] (1),

[0069] Wherein, is the motor inertia; is the mechanical angular velocity of the motor; is the derivative of the mechanical angular velocity of the motor; is the viscous friction coefficient; is the electromagnetic torque; is the load torque.

[0070] In the surface-mounted permanent magnet synchronous motor, the electromagnetic torque is expressed as:

[0071] (2),

[0072] Wherein, is the number of pole pairs of the motor; is the permanent magnet flux linkage; is q the measured current on the axis; let

[0073] According to equations (1) and (2), the mechanical motion equation is updated to:

[0074] (3),

[0075] Wherein, is the nominal value of the control system gain, is the nominal value of the permanent magnet flux linkage, is the nominal value of the moment of inertia; is the q-axis current reference value; is the total disturbance within the speed loop system, including but not limited to internal parameter perturbations, external load variations, and unknown or unmodeled dynamics.

[0076] The total disturbance is expressed as:

[0077] (4),

[0078] From equations (3) and (4), the extended state model is:

[0079] (5),

[0080] where, is the derivative of the total disturbance ; is the differential term of the total disturbance.

[0081] S2: Based on the extended state model, design a nonlinear extended state observer to estimate the total disturbance in real time.

[0082] In this embodiment, based on step S1, design a new type of nonlinear fast convergence function and a nonlinear extended state observer based on this function for quickly and real-time estimating the disturbances in the motor system. The traditional nonlinear convergence function is piecewise and has a limited convergence speed. To accelerate the convergence speed, design a new type of nonlinear fast convergence function , expressed as:

[0083] (6),

[0084] where, is the mechanical angular velocity estimation error, is the estimated mechanical angular velocity; , and are the parameters of the convergence function, , , ; is a constant; is the sign function;

[0085] is expressed as:

[0086] (7).

[0087] According to Equations (5) and (6), the nonlinear extended state observer is expressed as:

[0088] (8),

[0089] where, is the estimated total disturbance, and are the gain parameters of the nonlinear extended state observer, respectively.

[0090] S3: Design an error feedback control law based on the total disturbance to compensate for the disturbance and generate the q-axis current reference value.

[0091] In this embodiment, after the disturbance is accurately estimated, an error feedback control law is designed for disturbance compensation. According to the difference between the reference mechanical angular velocity command and the feedback mechanical angular velocity, an error signal is constructed and expressed as:

[0092]

[0093] where, is the reference mechanical angular velocity command, is the motor mechanical angular velocity;

[0094] The first derivative of

[0095] is: (9),

[0096] Based on the error feedback control strategy, the error proportional feedback is

[0097] is: (10),

[0098] where, is the control gain of the speed loop.

[0099] Substitute Equation (10) into Equation (9), and we get:

[0100] is: (11),

[0101] Substitute the and estimated by the nonlinear extended state observer into Equation (11), and the error feedback control law is:

[0102] is: (12).

[0103] Thus, the estimation and compensation of the disturbance are achieved.

[0104] Specifically, a surface-mounted permanent magnet synchronous motor is selected, and its parameters are as follows: the nominal value of the moment of inertia ; Nominal value of permanent magnet flux linkage ; Number of pole pairs of the motor ; Viscous friction coefficient ; Load torque Dynamically changes according to the actual working conditions, with a range of 0 to 10.

[0105] Establishment of mechanical motion equation: According to Equations (1) and (2), the electromagnetic torque coefficient is:[[]]

[0106]

[0107] The mechanical motion equation is transformed into Equation (3):

[0108]

[0109] Total disturbance Calculated according to Equation (4), including parameter perturbation, load variation and unmodeled dynamics.

[0110] According to Equations (3) and (4), the extended state model is expressed as:

[0111]

[0112] Set the parameters of the nonlinear fast convergence function as: , enhance the convergence speed when there is a large error; , optimize the smoothness in the small error region; , adjust the overall convergence strength; , used to suppress parameter sensitivity.

[0113] Then the nonlinear fast convergence function Equation (6) is expressed as:

[0114]

[0115] Through Lyapunov stability analysis, determine the observer gain , , the nonlinear extended state observer Equation (8):

[0116]

[0117] Build an observer model in Matlab / Simulink, set the initial velocity error , total disturbance . The simulation results show that the observer converges the error within 0.1 rad / s within 0.05 s, and the amplitude of chattering is less than 20% of that of the traditional sliding mode observer.

[0118] Design the error feedback control law: Set the control gain of the speed loop , ensure that the dynamic response bandwidth is 100 Hz. According to Equation (12), the q-axis current reference value is:

[0119]

[0120] Set the reference mechanical angular velocity command At Acceleration from Rise to . The experimental results show that the position error of the traditional phase-locked loop in the acceleration section reaches 2%, while the position compensation phase-locked loop of the present invention reduces the error to 0.3% and there is no overshoot.

[0121] Therefore, the present invention solves the defects of the traditional method in terms of chattering, convergence speed, and dynamic error through a novel nonlinear observer and a compensation phase-locked loop. The embodiments show that its position estimation accuracy and anti-interference ability are both improved, and it is applicable to industrial scenarios with high dynamics and strong interference.

[0122] Please refer to Figure 2 , which is a control block diagram of a permanent magnet synchronous motor control method according to 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 disturbances. The And Output by the observer are directly input to the controller to achieve closed-loop disturbance rejection.

[0123] Please refer to Figure 3 , which is a structural block diagram of a permanent magnet synchronous motor control method according to Embodiment 1. The transmission paths of each signal and the interaction relationships between modules are marked.

[0124] In summary, in Embodiment 1, the mechanical motion equation of the permanent magnet synchronous motor is first constructed to establish an extended state mathematical model; secondly, a novel nonlinear fast convergence function and a nonlinear extended state observer are designed to quickly and real-time estimate the disturbances in the motor system; finally, after the disturbances are 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 position and speed, thereby improving the control performance of the permanent magnet synchronous motor.

[0125] Embodiment 2

[0126] Please refer to Figure 4 , which is a structural schematic diagram of a permanent magnet synchronous motor control system according to this embodiment; the specific content includes:

[0127] Model construction module: According to the constructed mechanical motion equation of the permanent magnet synchronous motor, an extended state model is established.

[0128] Observer module: Based on the extended state model, a non-linear extended state observer is designed to estimate the total disturbance in real time.

[0129] 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.

[0130] In this embodiment, the extended state model is obtained through the model construction module. The observer module uses the extended state model to design a non-linear 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 achieve fast and accurate estimation and compensation of disturbances in the permanent magnet synchronous motor system, improving the control performance and operation stability of the motor.

[0131] It should be understood that various forms of the processes shown above can be used, reordering, adding, or deleting steps. For example, the steps recited in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved. No limitation is made herein.

[0132] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within 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; The specific steps include: Design nonlinear fast-converging functions , expressed as: （6）， in, is the mechanical angular velocity estimation error, is the motor mechanical angular velocity, 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）； 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, is the motor mechanical angular velocity The derivative of 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 number of motor pole pairs; 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; 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 1, 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.

5. A permanent magnet synchronous motor control method according to claim 4, 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）。 6. A permanent magnet synchronous motor control system, characterized in that: include: Model building module: Establish an expansion 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; specifically, the following steps are included: Design nonlinear fast-converging functions , expressed as: （6）， in, is the mechanical angular velocity estimation error, is the motor mechanical angular velocity, 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）； 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, is the motor mechanical angular velocity The derivative of 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 number of motor pole pairs; 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; 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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