CN114915227B - DC speed prediction control method of permanent magnet synchronous motor - Google Patents

Abstract

The invention relates to the technical field of motor control, in particular to a direct current speed prediction control method of a permanent magnet synchronous motor, which comprises the following steps: according to the voltage equation and the motion equation, a first prediction model and a cost function of the permanent magnet synchronous motor are established; analyzing to obtain a motor parameter error model, and outputting a second prediction model; obtaining a prediction error generated by mismatch of the electrical parameter and the mechanical parameter; outputting d and q axis disturbance and a rotating speed disturbance model; obtaining disturbance estimation values of d and q axis disturbance and rotation speed disturbance; and compensating the disturbance estimated value to the first prediction model to obtain the reference values of the electrical parameters and the mechanical parameters of the permanent magnet synchronous motor. And obtaining a disturbance estimated value of the established disturbance model based on the prediction error, compensating the disturbance estimated value to the first prediction model to obtain a third prediction model, and simultaneously considering disturbance generated by inaccurate electrical parameters and inaccurate mechanical parameters, thereby improving the dynamic performance and steady-state precision of the prediction model.

Description

A DC speed prediction control method for permanent magnet synchronous motor

Technical Field

The present invention relates to the technical field of motor control, and in particular to a DC speed prediction control method for a permanent magnet synchronous motor.

Background Art

Permanent magnet synchronous motor (PMSM) is a commonly used three-phase synchronous AC motor with high efficiency and high power density. With the increasing performance of motors, finite control set model predictive control (FCS-MPC) is increasingly used to improve the dynamic performance of control systems due to its simple implementation, easy handling of nonlinearities and constraints, and good dynamic performance.

Direct speed predictive control (MP-DSC) is one of the FCS-MPC control strategies, which can directly control the speed through the prediction model and objective function without adopting a cascade structure. However, the traditional MP-DSC is too dependent on the accuracy of the model parameters and load torque. In practical applications, when the parameters do not match, the performance of the system will deteriorate. In fact, when the permanent magnet synchronous motor operates under various working environments, the ambient temperature, magnetic saturation and load conditions will change dramatically, which will have a significant impact on the motor parameters.

Therefore, when the system parameters are inaccurate or change, the predicted reference parameters will be inaccurate, resulting in reduced robustness of the entire motor.

Summary of the invention

The present invention provides a DC speed prediction control method for a permanent magnet synchronous motor, which is used to solve the defects in the above-mentioned prior art.

The present invention provides a DC speed prediction control method for a permanent magnet synchronous motor, which is characterized by comprising the steps of:

S1 establishes a first prediction model and a cost function of the permanent magnet synchronous motor according to the voltage equation and the motion equation in the synchronous coordinate system of the permanent magnet synchronous motor;

S2 obtains a motor parameter error model based on the first prediction model analysis, outputs a second prediction model, and obtains a prediction error caused by the mismatch between electrical parameters and mechanical parameters;

S3 reconstructs the voltage equation and the motion equation based on the prediction error, and outputs the d-axis and q-axis disturbance and speed disturbance models;

S4 obtains a full-parameter disturbance observer to obtain disturbance estimation values of d-axis and q-axis disturbances and speed disturbances;

S5 compensates the disturbance estimation value to the first prediction model, obtains a third prediction model, and obtains the prediction value of the electrical parameter of the permanent magnet synchronous motor through the third prediction model.

According to a DC speed prediction control method for a permanent magnet synchronous motor provided by the present invention, the voltage equation and the motion equation in step S1 are:

The prediction model obtained by using the first-order Euler discretization method is:

Wherein, i _d , i _q are the d-axis and q-axis current components in the synchronous coordinate system, respectively; _ud , _uq are the d-axis and q-axis voltage components in the synchronous coordinate system, respectively; R _s , L _s , ψ _f represent the stator resistance, stator inductance, and permanent magnet flux linkage, respectively; J, B, and p represent the moment of inertia, damping coefficient, and pole pair number, respectively; ω _e is the rotor electrical speed, ω _r is the rotor mechanical speed, _Te is the electromagnetic torque, and _TL is the load torque;

i _d (k) and i _q (k) are the d-axis and q-axis current sampling values in the synchronous coordinate system at moment k, respectively; _ud (k) and u _q (k) are the d-axis and q-axis voltage sampling values in the synchronous coordinate system at moment k, respectively; i ^p _d (k+1), i ^p _q (k+1) and are the d-axis and q-axis current prediction values in the synchronous coordinate system at moment k+1, respectively; ω _e (k) is the rotor electrical speed sampling value at moment k; ω ^p _e (k+1) is the rotor electrical speed prediction value at moment k+1; T _s is the sampling period; _TL (k) is the load torque sampling value at moment k.

According to a DC speed prediction control method for a permanent magnet synchronous motor provided by the present invention, in step S2, the second prediction model is:

Among them, ΔR, ΔL, Δψ _f represent the errors between the actual value and the nominal value of the stator resistance, stator inductance, and permanent magnet flux linkage, respectively; ΔJ and ΔB represent the errors between the actual value and the nominal value of the moment of inertia and damping coefficient, respectively;

The electrical parameters and mechanical parameters include resistance parameters, inductance parameters and flux linkage parameters, and the mechanical parameters include damping coefficient, load torque and moment of inertia.

According to a DC speed prediction control method for a permanent magnet synchronous motor provided by the present invention, in step S2, the first prediction model is subtracted from the second prediction model to obtain the prediction error caused by the mismatch between electrical parameters and mechanical parameters:

E _d is the electrical parameter prediction error of the d-axis, E _q is the electrical parameter prediction error of the q-axis, and E _ω is the speed prediction error.

According to a DC speed prediction control method for a permanent magnet synchronous motor provided by the present invention, in S3, the voltage equation and the motion equation are reconstructed to obtain:

The d-axis, q-axis disturbance and speed disturbance models are established as follows:

Among them, _fd is the d-axis disturbance, _fq is the q-axis disturbance, and _fω is the speed disturbance.

According to a DC speed prediction control method for a permanent magnet synchronous motor provided by the present invention, in S4, the full parameter disturbance observer is:

Wherein: z ₁ , z ₂ , z ₃ are intermediate variables of the full parameter disturbance observer, l is the gain of the disturbance observer; is the d-axis disturbance estimate, is the estimated value of the q-axis disturbance, is the estimated value of the speed disturbance.

According to a DC speed prediction control method for a permanent magnet synchronous motor provided by the present invention, in S5, the third prediction model is:

in, is the estimated value of the d-axis disturbance at the kth moment, is the estimated value of the q-axis disturbance at the kth moment, is the estimated value of the speed disturbance at the kth moment.

The present invention also provides a permanent magnet synchronous motor direct speed prediction control system, which is used to execute the steps of any of the above-mentioned DC speed prediction control methods to predict the electrical parameters and mechanical parameters of the permanent magnet synchronous motor, and output the predicted values of the corresponding parameters.

The present invention also provides a non-transitory computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above-mentioned DC speed prediction control methods are implemented.

The present invention provides a direct speed prediction control method for a permanent magnet synchronous motor. The method obtains a prediction error caused by the mismatch between electrical parameters and mechanical parameters, obtains disturbance estimation values of d-axis and q-axis disturbances and speed disturbances in an established disturbance model based on the prediction error, and compensates the disturbance estimation values to the first prediction model to obtain a third prediction model. The method also takes into account the disturbances caused by inaccurate electrical parameters and inaccurate mechanical parameters, thereby improving the dynamic performance and steady-state accuracy of the prediction model.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic flow chart of a method for direct speed prediction control of a permanent magnet synchronous motor provided by the present invention;

FIG2 is one of the error distribution diagrams of the direct speed prediction control method of a permanent magnet synchronous motor provided by the present invention;

FIG3 is a second error distribution diagram of the direct speed prediction control method for a permanent magnet synchronous motor provided by the present invention;

FIG4 is a third error distribution diagram of the direct speed prediction control method for a permanent magnet synchronous motor provided by the present invention;

FIG5 is a fourth error distribution diagram of the direct speed prediction control method for a permanent magnet synchronous motor provided by the present invention;

FIG6 is a fifth error distribution diagram of the direct speed prediction control method for a permanent magnet synchronous motor provided by the present invention;

7 is a sixth error distribution diagram of the direct speed prediction control method for a permanent magnet synchronous motor provided by the present invention;

8 is a schematic diagram of the structure of a direct speed prediction control system for a permanent magnet synchronous motor provided by the present invention;

FIG9 is a schematic diagram of a result obtained by using conventional direct speed prediction control in the prior art;

FIG10 is a schematic diagram of one of the results obtained by the direct speed prediction control method provided by the present invention;

FIG11 is a second schematic diagram of the results obtained by using the conventional direct speed predictive control in the prior art;

FIG12 is a second schematic diagram of the results obtained by the direct speed prediction control method provided by the present invention;

FIG13 is a third schematic diagram of the results obtained by using the conventional direct speed prediction control in the prior art;

FIG. 14 is a third schematic diagram of the results obtained by the direct speed prediction control method provided by the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The terms "first", "second", "third", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

In one embodiment, as shown in FIG1 , the present invention provides a DC speed prediction control method for a permanent magnet synchronous motor, comprising the steps of:

S1 establishes a first prediction model and a cost function of the permanent magnet synchronous motor according to the voltage equation and the motion equation in the synchronous coordinate system of the permanent magnet synchronous motor;

S2 obtains a motor parameter error model based on the first prediction model analysis, outputs a second prediction model, and obtains a prediction error caused by the mismatch between electrical parameters and mechanical parameters;

S3 reconstructs the voltage equation and the motion equation based on the prediction error, and outputs the d-axis and q-axis disturbance and speed disturbance models;

S4 obtains a full-parameter disturbance observer to obtain disturbance estimation values of d-axis and q-axis disturbances and speed disturbances;

S5 compensates the disturbance estimation value to the first prediction model, obtains a third prediction model, and obtains the prediction value of the electrical parameter of the permanent magnet synchronous motor through the third prediction model.

According to a DC speed prediction control method for a permanent magnet synchronous motor provided by the present invention, the voltage equation and the motion equation in step S1 are:

The prediction model obtained by using the first-order Euler discretization method is:

Wherein, i _d , i _q are the d-axis and q-axis current components in the synchronous coordinate system, respectively; _ud , _uq are the d-axis and q-axis voltage components in the synchronous coordinate system, respectively; R _s , L _s , ψ _f represent the stator resistance, stator inductance, and permanent magnet flux linkage, respectively; J, B, and p represent the moment of inertia, damping coefficient, and pole pair number, respectively; ω _e is the rotor electrical speed, ω _r is the rotor mechanical speed, _Te is the electromagnetic torque, and _TL is the load torque;

i _d (k) and i _q (k) are the d-axis and q-axis current sampling values in the synchronous coordinate system at time k, respectively; _ud (k) and u _q (k) are the d-axis and q-axis voltage sampling values in the synchronous coordinate system at time k, respectively; i ^p _d (k+1), i ^p _q (k+1) and are the d-axis and q-axis current prediction values in the synchronous coordinate system at time k+1, respectively; ω _e (k) is the rotor electrical speed sampling value at time k; ω ^p _e (k+1) is the rotor electrical speed prediction value at time k+1; T _s is the sampling period; _TL (k) is the load torque sampling value at time k;

is the average electromagnetic torque at time k, specifically:

Among them, the established cost function is:

Where, ω ^* is the given electrical speed, is the given q-axis current, λ _d is the d-axis current weight coefficient, and λ _q is the q-axis current weight coefficient;

The optimal current prediction value and the corresponding optimal voltage vector can be found through the established cost function.

Further, according to the first prediction model established in the above steps, the error model is analyzed when the resistance, inductance, flux linkage, moment of inertia, damping coefficient and load torque are inaccurate, and the influence of direct speed prediction control when various electrical parameters and mechanical parameters are inaccurate is obtained by qualitative analysis;

Specifically, the electrical parameters and mechanical parameters are inaccurate when the values of the various electrical parameters and mechanical parameters obtained are different from the actual values of the various electrical parameters and mechanical parameters during the operation of the motor. In step S2, the first prediction model is rewritten based on the error, and the second prediction model obtained is:

Among them, ΔR, ΔL, Δψ _f represent the errors between the actual value and the nominal value of the stator resistance, stator inductance, and permanent magnet flux linkage, respectively; ΔJ and ΔB represent the errors between the actual value and the nominal value of the moment of inertia and damping coefficient, respectively;

Wherein, the nominal value is the standard parameter of the corresponding physical quantity;

The electrical parameters and mechanical parameters include resistance parameters, inductance parameters and flux linkage parameters, and the mechanical parameters include damping coefficient, load torque and moment of inertia.

Further, in step S2, the first prediction model is subtracted from the second prediction model to obtain the prediction error caused by the mismatch between the electrical parameters and the mechanical parameters:

E _d is the electrical parameter prediction error of the d-axis, E _q is the electrical parameter prediction error of the q-axis, and E _ω is the speed prediction error;

Specifically, as shown in Figure 2-7, inaccuracies in inductance parameters, flux parameters, damping coefficient and load torque are the main factors causing prediction errors, while the errors caused by inaccuracies in moment of inertia and resistance parameters are smaller.

Further, in step S3, based on the errors of the electrical parameters and mechanical parameters relative to the corresponding actual values, the voltage equation and the motion equation in step S1 are reconstructed to obtain:

The d-axis, q-axis disturbance and speed disturbance models are established as follows:

Among them, _fd is the d-axis disturbance, _fq is the q-axis disturbance, and _fω is the speed disturbance.

Further, in step S4, a full parameter disturbance observer is established to observe the d-axis and q-axis disturbances and the speed disturbance model in step S3:

Wherein, z ₁ , z ₂ , z ₃ are intermediate variables of the full parameter disturbance observer, and l is the gain of the disturbance observer; is the d-axis disturbance estimate, is the estimated value of the q-axis disturbance, is the estimated value of the speed disturbance;

Specifically, the observation error It is expressed as:

Create a Lyapunov function:

Derivative the above formula:

From the above formula, we can see that according to the Lyapunov stability criterion, as long as the observer parameters satisfy l<0, the observer stability can be ensured, thus obtaining the parameter value range of the observer.

Furthermore, in step S5, the disturbance measured in step S4 is compensated to the first prediction model, as shown in FIG8 , and the obtained third prediction model is:

in, is the estimated value of the d-axis disturbance at the kth moment, is the estimated value of the q-axis disturbance at the kth moment, is the estimated value of the speed disturbance at the kth moment;

is the average electromagnetic torque at time k, specifically:

The improved prediction model takes into account the impact of inaccuracies in all electrical and mechanical parameters, effectively improving the robustness of the system.

Specifically, in one embodiment, the above method is used to predict the electrical parameters and mechanical parameters of the motor. Figures 9-10 show the speed tracking waveforms of the motor running under 1500r/min, 2N·m conditions when the motor adopts traditional direct speed prediction control and the direct speed prediction control method described in the present invention. It can be seen that the present invention better achieves the simulation of the actual speed value; Figures 11-12 show the q-axis current tracking waveforms of the motor running when the motor adopts traditional direct speed prediction control and the direct speed prediction control method described in the present invention. It can be seen that the present invention better achieves the accuracy of the current prediction value; Figures 13-14 show the q-axis current spectrum diagrams of the motor running when the motor adopts traditional direct speed prediction control and the direct speed prediction control method described in the present invention;

It can be seen that the present invention achieves improvement in the parameter robustness of the traditional direct speed predictive control, helps to improve the dynamic performance and steady-state accuracy of the system, and can improve the prediction accuracy of electrical parameters and mechanical parameters.

The present invention also provides a permanent magnet synchronous motor direct speed prediction control system, which is used to execute the steps of any of the above-mentioned DC speed prediction control methods to predict the electrical parameters and mechanical parameters of the permanent magnet synchronous motor, and output the predicted values of the corresponding parameters.

On the other hand, the present invention also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute a DC speed prediction control method for a permanent magnet synchronous motor provided by the above methods, including the following steps: S1 establishes a first prediction model and a cost function of the permanent magnet synchronous motor according to the voltage equation and the motion equation in the synchronous coordinate system of the permanent magnet synchronous motor; S2 obtains a motor parameter error model based on the first prediction model analysis, outputs a second prediction model, and obtains a prediction error caused by the mismatch between electrical parameters and mechanical parameters; S3 reconstructs the voltage equation and the motion equation based on the prediction error, and outputs a d-axis disturbance and a speed disturbance model; S4 obtains a full-parameter disturbance observer, obtains disturbance estimation values of the d-axis disturbance and the q-axis disturbance and the speed disturbance; S5 compensates the disturbance estimation value to the first prediction model, obtains a third prediction model, and obtains reference values of the electrical parameters and mechanical parameters of the permanent magnet synchronous motor through the third prediction model.

On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the processor executes the above-mentioned method for predicting and controlling the DC speed of a permanent magnet synchronous motor, including the following steps: S1 establishes a first prediction model and a cost function of the permanent magnet synchronous motor according to the voltage equation and the motion equation in the synchronous coordinate system of the permanent magnet synchronous motor; S2 obtains a motor parameter error model based on the analysis of the first prediction model, outputs a second prediction model, and obtains a prediction error caused by the mismatch between electrical parameters and mechanical parameters; S3 reconstructs the voltage equation and the motion equation based on the prediction error, and outputs a d-axis disturbance and a speed disturbance model; S4 obtains a full-parameter disturbance observer, obtains disturbance estimation values of the d-axis disturbance and the q-axis disturbance and the speed disturbance; S5 compensates the disturbance estimation value to the first prediction model, obtains a third prediction model, and obtains reference values of the electrical parameters and mechanical parameters of the permanent magnet synchronous motor through the third prediction model.

The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative work.

Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM/RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A method for predicting and controlling the DC speed of a permanent magnet synchronous motor, comprising the steps of: S1 establishes a first prediction model and a cost function of the permanent magnet synchronous motor according to the voltage equation and the motion equation in the synchronous coordinate system of the permanent magnet synchronous motor; S2 obtains a motor parameter error model based on the first prediction model analysis, outputs a second prediction model, and obtains a prediction error caused by the mismatch between electrical parameters and mechanical parameters; S3 reconstructs the voltage equation and the motion equation based on the prediction error, and outputs the d-axis and q-axis disturbance and speed disturbance models; S4 obtains a full-parameter disturbance observer to obtain disturbance estimation values of d-axis and q-axis disturbances and speed disturbances; S5 compensates the disturbance estimation value to the first prediction model, obtains a third prediction model, and obtains reference values of electrical parameters and mechanical parameters of the permanent magnet synchronous motor through the third prediction model. 2. A DC speed prediction control method for a permanent magnet synchronous motor according to claim 1, characterized in that the voltage equation and motion equation in step S1 are: ; The first prediction model is obtained using the first-order Euler discretization method: in, , are the d-axis and q-axis current components in the synchronous coordinate system, , are the d-axis and q-axis voltage components in the synchronous coordinate system respectively; , , They represent stator resistance, stator inductance, and permanent magnet flux respectively; , , They represent the moment of inertia, damping coefficient, and pole pair number respectively; is the rotor electrical speed, is the rotor mechanical speed, is the electromagnetic torque, is the load torque; , are the d-axis and q-axis current sampling values in the synchronous coordinate system at time k, , are the d-axis and q-axis voltage sampling values in the synchronous coordinate system at time k respectively; , and are the predicted values of d-axis and q-axis currents in the synchronous coordinate system at the k+1th moment, respectively; is the rotor electrical speed sampling value at the kth moment; is the predicted value of the rotor electrical speed at the k+1th moment; is the sampling period; is the load torque sampling value at the kth moment. 3. The method for predicting and controlling the DC speed of a permanent magnet synchronous motor according to claim 2, characterized in that, in step S2, the second prediction model is: ; in, , , Respectively represent the error between the actual value and the nominal value of the stator resistance, stator inductance, and permanent magnet flux; , Respectively represent the errors between the true value and the nominal value of the moment of inertia and the damping coefficient; The electrical parameters and mechanical parameters include resistance parameters, inductance parameters and flux linkage parameters, and the mechanical parameters include damping coefficient, load torque and moment of inertia. 4. A method for predicting and controlling the DC speed of a permanent magnet synchronous motor according to claim 3, characterized in that, in step S2, the first prediction model is subtracted from the second prediction model to obtain the prediction error caused by the mismatch between electrical parameters and mechanical parameters: ; is the electrical parameter prediction error of the d-axis, is the electrical parameter prediction error of the q-axis, is the speed prediction error, is the moment of inertia error, is the damping coefficient error. 5. The method for predicting and controlling the DC speed of a permanent magnet synchronous motor according to claim 4, characterized in that, in S3, the voltage equation and the motion equation are reconstructed to obtain: ; The d-axis, q-axis disturbance and speed disturbance models are established as follows: ; in, is the d-axis disturbance, is the q-axis disturbance, The speed disturbance. 6. The method for predictive control of DC speed of a permanent magnet synchronous motor according to claim 5, characterized in that, in S4, the full parameter disturbance observer is: ; in: , , is the intermediate variable of the full parameter disturbance observer, is the gain of the disturbance observer; is the d-axis disturbance estimate, is the estimated value of the q-axis disturbance, is the estimated value of the speed disturbance. 7. A method for predicting and controlling the DC speed of a permanent magnet synchronous motor according to claim 6, characterized in that, in S5, the third prediction model is: ; in, is the estimated value of the d-axis disturbance at the kth moment, is the estimated value of the q-axis disturbance at the kth moment, is the estimated value of the speed disturbance at the kth moment. 8. A permanent magnet synchronous motor direct speed prediction control system, characterized in that the permanent magnet synchronous motor direct speed prediction control system executes the steps of the DC speed prediction control method as described in any one of claims 1 to 7 to predict the electrical parameters and mechanical parameters of the permanent magnet synchronous motor, and outputs reference values of the corresponding parameters. 9. A non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the DC speed prediction control method according to any one of claims 1 to 7 are implemented.