Control method for disturbance suppression of permanent magnet synchronous linear motor system

Abstract

The invention relates to a control method for disturbance suppression of a permanent magnet synchronous linear motor system, and the method comprises the steps: detecting the position of a rotor in real time, and building a permanent magnet synchronous linear motor mathematical model related to the position of the rotor; designing a disturbance observer based on the permanent magnet synchronous linear motor mathematical model, and estimating end effect disturbance and load disturbance existing in the operation process of the permanent magnet synchronous linear motor in real time by using the disturbance observer; based on the end effect interference and the load disturbance estimated by the interference observer, constructing a sliding mode controller, and inputting an output result of the interference observer into the permanent magnet synchronous linear motor system by using the sliding mode controller so as to control the speed of the permanent magnet synchronous linear motor; a mathematical model related to the position of the rotor is constructed by detecting the position of the rotor in real time to provide a basis for the design of the disturbance observer, so that the disturbance observer can estimate and compensate errors caused by an end effect and load change in real time, and high-precision speed control of the motor is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a control method for disturbance suppression in a permanent magnet synchronous linear motor system. Background Art

[0002] As an efficient driving device that directly converts electrical energy into linear motion, the Permanent Magnet Linear Synchronous Motor (PMLSM) has been widely used in fields such as precision machining, semiconductor manufacturing, automated logistics, and high-speed rail transit due to its advantages of high thrust density, fast dynamic response, and high positioning accuracy. However, in actual operation, the PMLSM faces a complex disturbance environment, such as end effects, load mutations, and friction changes. These disturbances can cause speed fluctuations, increased positioning errors, and even system instability. Although a large amount of research has been carried out on control strategies in the academic and industrial fields, there are still many limitations in the existing technologies, making it difficult to meet the industrial requirements of high precision and high robustness.

[0003] Currently, there are many methods for disturbance observation and compensation in the control field, mainly including PID control, sliding mode control, robust control, DOB, ESO, etc. Among them, the ID control method relies on fixed parameter adjustment, has a slow response to dynamic disturbances (such as end effects and load mutations), is prone to overshoot or steady-state errors, and has poor adaptability especially under complex working conditions; although the sliding mode control (SMC) method has strong robustness, its discontinuous switching characteristics will cause high-frequency chattering, which will aggravate mechanical wear and reduce system stability; when the disturbance observer (DOB) method is used alone, it has insufficient modeling accuracy for mismatched disturbances (such as end effects strongly related to the mover position), and the estimation speed of medium- and high-frequency disturbances is limited, making it difficult to meet the real-time compensation requirements; some studies have tried to combine DOB and SMC to improve the disturbance rejection ability, but there are still defects: the influence of the mover position on the disturbance (such as the end effect disturbance term) is not fully considered, resulting in a large deviation between the disturbance model and the actual situation and insufficient observation accuracy; the SMC chattering problem has not been effectively solved, and improper selection of control gains may exacerbate system oscillation; the computational complexity is high, the gain matrix configuration method is not optimized, and it is difficult to achieve efficient operation in real-time control.

[0004] During the operation of the PMLSM, the change of the mover position will significantly change the electromagnetic parameters and disturbance characteristics. For example, the nonlinear change of the magnetic flux caused by the end effect is difficult to accurately model by traditional methods; when the load mutates, the existing controller needs to rely on accurate load information, otherwise it will lead to speed tracking failure. In addition, the industrial scenario has strict requirements for the real-time performance and computational efficiency of the control system, and it is difficult for the existing methods to balance performance and cost in an environment with limited resources.

[0005] In summary, it is difficult for the existing technology to achieve high-precision and low-chattering speed control in a complex disturbance environment (such as end effect and unknown load). Therefore, there is an urgent need for a control method that can estimate position-related disturbances in real time, dynamically compensate for interference, and at the same time reduce the computational complexity, so as to improve the robustness and applicability of the PMLSM system. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a control method for suppressing disturbances in a permanent magnet synchronous linear motor system, which fully considers the mover position, estimates position-related disturbances in real time, effectively suppresses disturbances, improves the observation accuracy, effectively solves the SMC chattering problem, reduces the system computational complexity, and improves the system robustness and applicability.

[0007] The technical solution adopted by the present invention is a control method for suppressing disturbances in a permanent magnet synchronous linear motor system, and the method includes the following steps:

[0008] S1. Detect the position of the mover in real time, and establish a mathematical model of the permanent magnet synchronous linear motor related to the position of the mover;

[0009] S2. Based on the mathematical model of the permanent magnet synchronous linear motor, design an interference observer, and use the interference observer to estimate the end effect interference and load disturbance existing in the operation of the permanent magnet synchronous linear motor in real time;

[0010] S3. Based on the end effect interference and load disturbance estimated by the interference observer, construct a sliding mode controller, and use the sliding mode controller to input the end effect interference and load disturbance obtained by the real-time estimation of the interference observer into the permanent magnet synchronous linear motor system to control the speed of the permanent magnet synchronous linear motor in the permanent magnet synchronous linear motor system.

[0011] Preferably, the specific process of step S1 includes the following steps:

[0012] S1.1. Detect the position of the mover in real time, and establish the dynamic equation and q-axis voltage equation of the permanent magnet synchronous linear motor related to the position of the mover, and the expressions are:

[0013] where x represents the real-time position of the mover, l represents the effective length of the mover, s represents the effective length of the stator segment, ψ f represents the permanent magnet flux linkage when the mover and the stator are fully coupled, L s represents the self-inductance of the stator winding when the mover and the stator are fully coupled, L σ represents the leakage inductance of the stator winding, M represents the mass of the mover, F t represents the sum of the load resistance, magnetic resistance and frictional force, B represents the viscous friction coefficient, Rs represents the stator equivalent resistance, τ represents the electromagnetic pole pitch, v s represents the mover speed, u q represents the q-axis voltage of the stator, i d and i q respectively represent the d-axis current and the q-axis current, L s represents the synchronous inductance, ψ d and ψ q respectively represent the d-axis stator flux linkage and the q-axis stator flux linkage; Pn represents the number of pole pairs, ΔM represents the unknown load change, Δψ f represents the change in the permanent magnet flux linkage;

[0014] S1.2. Based on the above kinetic equation and q-axis voltage equation, establish a mathematical model of the permanent magnet synchronous linear motor related to the position of the mover, and its expression is:

[0015] where, d v represents the speed error; d i represents the q-axis current error.

[0016] Preferably, the specific process of step S2 includes the following steps:

[0017] S2.1. Set the unknown disturbance existing in the operation process of the permanent magnet synchronous linear motor as: where, λ represents the disturbance auxiliary variable, d represents the system error matrix; W and and V both represent the coefficient matrices, ω represents the error frequency, k1 and k2 both represent the conversion coefficients;

[0018] S2.2. Introduce the unknown disturbance existing in the operation process of the permanent magnet synchronous linear motor set in step S2.1 into the mathematical model of the permanent magnet synchronous linear motor, and obtain the mathematical model of the permanent magnet synchronous linear motor after adding the disturbance observer, and its expression is:

[0019]

[0020] S2.3. Transform the mathematical model of the permanent magnet synchronous linear motor after adding the disturbance observer into matrix form, specifically:

[0021] S2.4. The subsystem that only contains the disturbance term is expressed as:

[0022] S2.5. Design a disturbance observer according to the above subsystem, and the expression of the disturbance observer is: where, x=[x1x2] T =[v s i q ] T , λ represents the interference auxiliary variable, represents the estimated value of the interference auxiliary variable λ; η represents the interference auxiliary variable, E d represents the gain matrix of the disturbance observer, represents the estimated value of the interference auxiliary variable η; σ represents the equivalent output of the subsystem;

[0023] S2.6. Use the designed disturbance observer to estimate the end effect disturbance and load disturbance in the operation of the permanent magnet synchronous linear motor in real time.

[0024] Preferably, the expression of the sliding mode controller is:

[0025] Among them, D c =cB d1 +B d2 , s represents the synovial surface, k and c represent adjustment parameters.

[0026] The beneficial effects of the present invention are as follows: the present invention utilizes disturbances observed in real time in the permanent magnet synchronous linear motor system to ensure that the motor can maintain high-precision speed control under different load and dynamic conditions. Real-time detection of the mover position is used to construct a mathematical model related to the mover position, providing a basis for the design of an interference observer, enabling the interference observer to estimate and compensate for errors caused by end effects and load changes in real time, ensuring high-precision speed control of the motor, while sliding mode control provides strong robustness and improves the response speed and stability of the system. The control method proposed in the present invention greatly improves the performance of the permanent magnet synchronous linear motor system and provides more reliable technical support for its efficient application in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a control method for disturbance suppression of a permanent magnet synchronous linear motor system according to the present invention;

[0028] Figure 2 Schematic diagram of the permanent magnet synchronous linear motor system in the present invention;

[0029] Figure 3 This is a comparison diagram of speed fluctuations using the traditional PID control method and the control method of the present invention after entering the stator at 0.3s in the simulation experiment of the present invention;

[0030] Figure 4It is the speed response curve diagram when the mass of the entire mover is tripled during the simulation experiment in the present invention and the traditional PID control method is adopted.

[0031] Figure 5 It is the speed response curve diagram when the mass of the entire mover is tripled during the simulation experiment in the present invention and the control method of the present invention is adopted. Specific embodiments

[0032] The following further describes the invention with reference to the accompanying drawings and in conjunction with specific embodiments, so that those skilled in the art can implement it according to the description in the specification. The protection scope of the present invention is not limited to this specific embodiment.

[0033] The present invention relates to a control method for disturbance suppression in a permanent magnet synchronous linear motor system, as Figure 1 shown, this method includes the following steps:

[0034] S1. Detect the position of the mover in real time and establish a mathematical model of the permanent magnet synchronous linear motor related to the position of the mover;

[0035] Specifically, the specific process of establishing a mathematical model of the permanent magnet synchronous linear motor related to the position of the mover is as follows:

[0036] The control of the permanent magnet synchronous linear motor usually adopts the control strategy of i d =0, and its basic model is expressed as:

[0037]

[0038] Among them, M represents the mass of the mover, F t represents the sum of the load resistance, magnetic resistance, and frictional force, B represents the viscous friction coefficient. R s represents the equivalent resistance of the stator, τ represents the electromagnetic pole pitch, v s represents the speed of the mover, u q represents the stator q-axis voltage, i d and i q respectively represent the d-axis and q-axis currents, L s represents the synchronous inductance, ψ d and ψ q respectively represent the d-axis and q-axis stator magnetic fluxes;

[0039] The magnetic flux change expression when the mover enters and completely exits the stator section is:

[0040]

[0041] Among them, x represents the real-time position of the mover, l represents the effective length of the mover, s represents the effective length of the stator section, and the section where the mover enters the stator is regarded as the starting zero point, ψf is the permanent magnet flux linkage when the mover and the stator are fully coupled;

[0042] For a permanent magnet linear synchronous motor, when the mover poles and the stator windings are fully coupled, the inductance of the stator windings reaches its maximum value. When the mover completely exits the stator section, due to the existence of leakage inductance, the inductance does not decrease to zero. Similar to the variation law of the flux linkage at the stator ends, the expression for the inductance variation when the mover enters and then completely exits the stator section is:

[0043]

[0044] where L s represents the self - inductance of the stator windings when the mover and the stator are fully coupled, and L σ represents the leakage inductance of the stator windings;

[0045] Real - time detect the position of the mover, and establish the dynamic equation and q - axis voltage equation of the permanent magnet synchronous linear motor related to the position of the mover. Their expressions are:

[0046]

[0047] where Pn represents the number of pole pairs, ΔM represents the unknown load change, and Δψ f represents the change in permanent magnet flux linkage.

[0048] Based on the above - mentioned dynamic equation and q - axis voltage equation, establish a mathematical model of the permanent magnet synchronous linear motor related to the position of the mover. Its expression is:

[0049]

[0050] Take the state variable x = [x1 x2] T = [v s i q T , and after writing it in a simplified form, we get:

[0051]

[0052] where, C = [1 0].

[0053] 2. Based on the above - mentioned mathematical model of the permanent magnet synchronous linear motor, design a disturbance observer, and use the disturbance observer to estimate in real - time the end - effect disturbance and load disturbance existing during the operation of the permanent magnet synchronous linear motor;

[0054] Specifically, in an actual system, external disturbances can be described by a specific model. Therefore, the disturbance of the permanent magnet synchronous linear motor is defined in the form of formula (7): ​

[0055]

[0056] Among them, λ represents the interference auxiliary variable; and represents the coefficient matrix;

[0057] Introduce the perturbation formula (7) into the mathematical model of the permanent magnet synchronous linear motor, and the mathematical model of the permanent magnet synchronous linear motor after adding the disturbance observer is obtained. Its expression is:

[0058]

[0059] If the interference auxiliary variable λ can be accurately estimated, then the estimated value of d can be directly obtained through d = Vλ, that is, the estimation problem of the perturbation d is transformed into the estimation problem of the interference auxiliary variable λ;

[0060] Writing the formula (8) in matrix form gives:

[0061]

[0062] Obtain the subsystem that only contains the interference term:

[0063]

[0064] where σ is the equivalent output of the subsystem.

[0065] According to the formula (10), the following disturbance observer is designed:

[0066]

[0067] where is the estimated value of the interference auxiliary variable λ; is the estimated value of the equivalent output σ of the subsystem; E d is the observer gain matrix;

[0068] The formula (11) contains the differential term of the state variable which increases the calculation difficulty of the observation system. Define the auxiliary variable to replace the differential term Finally, the disturbance observer is obtained as:

[0069]

[0070] where, is the interference estimated value;

[0071] From the formula (12), the state equation of the interference estimated value can be obtained as:

[0072]

[0073] Among them, e d Represents the error between the true interference value and the estimated value, and then the estimated error satisfies the following relationship:

[0074]

[0075] S3, based on the end effect disturbance and load disturbance estimated by the disturbance observer, construct a sliding mode controller, and use the sliding mode controller to convert the output result of the disturbance observer (system error estimate) ) is input into the permanent magnet synchronous linear motor system, such as Figure 2 As shown, the speed of the permanent magnet synchronous linear motor in the permanent magnet synchronous linear motor system is controlled; Figure 2 In the sliding mode controller (SMC), the reference speed v ref and the speed and current error estimates fed back by the disturbance observer (DOB) Generate control voltage u q , and then the voltage signal is converted to u in the αβ coordinate system through Park transformation α and u β These voltage signals are modulated by space vector pulse width modulation (SWPWM) to generate three-phase PWM signals u a ,u b ,u c , the PMLSM is driven by the inverter. The three-phase current feedback signal i a ,i b， i c， The feedback current i is converted into the dq coordinate system through Clark and Park transformation d and i q , and sent back to the d-axis PID controller and disturbance observer. The disturbance observer estimates the disturbance in the system by detecting the speed and current, and feeds the disturbance estimation value back to the sliding mode controller in real time.

[0076] The expression of the sliding mode controller is:

[0077]

[0078] Among them, D c =cB d1 +B d2 .

[0079] Compared with the traditional sliding film control, the control rate introduces the disturbance estimation value of DOB observation, which makes the value of K smaller during design, thereby effectively reducing the vibration.

[0080] The following simulation experiments are used to illustrate the superiority of the control method for disturbance suppression of a permanent magnet synchronous linear motor system of the present invention.

[0081] The control method for disturbance suppression in a permanent magnet synchronous linear motor system of the present invention is simulated and compared with the traditional PID control method:

[0082] Use the simulink simulation software for simulation, and perform the simulation based on the parameters shown in the following table:

[0083] Table 1 Simulation parameter settings

[0084] Symbol Parameter type Numerical value <![CDATA[P n > Number of pole pairs 5 M Rotor mass 5 kg B Viscous friction coefficient 0.3 τ Pole pitch 20 mm <![CDATA[L s > Synchronous inductance 4.68 mH <![CDATA[Ψ f > Permanent magnet flux linkage 0.02 Wb v Rotor speed 0.5 m / s

[0085] The simulation results are as follows: Figure 3 As shown, it enters the stator at a speed of 0.5 m / s at 0.3 s, and the comparison results of the speed fluctuations of the method of the present invention and the traditional PID control method are obtained. From Figure 2 it can be seen that the traditional PID control method has poor dynamic performance, and there are obvious speed fluctuations when the system faces disturbances, making it difficult to accurately track the given speed command. In contrast, after adopting the control method of the present invention, the system performance has been significantly optimized. First, the control method of the present invention effectively eliminates the overshoot phenomenon, making the motor start more smoothly; second, the steady-state response time of the system is greatly shortened, and it can reach the target speed more quickly, improving the control accuracy and dynamic performance.

[0086] To ensure the influence of load changes on the system, during the simulation, the entire mover mass is changed to 3 times the original to observe the speed response characteristics of the motor.

[0087] From Figure 4 and Figure 5 it can be seen that when the mover mass changes, the adaptability of the traditional PID control method is poor, leading

[0088] to a significant increase in the overshoot, affecting the stability of the system. After adopting the control method of the present invention, the speed response curves before and after the change of the mover mass change little, which indicates that the control method combining the disturbance observer and the sliding mode can effectively suppress the disturbance, has stronger robustness and anti-interference ability, so as to ensure that the system still maintains good dynamic performance under different load conditions.

[0089] To suppress the disturbance during the operation of the permanent magnet synchronous linear motor, the present invention proposes a mathematical model of the permanent magnet synchronous linear motor based on the mover position, and combines a control method of a disturbance observer (DOB) and a sliding mode controller (SMC), so as to effectively suppress the influence of the errors caused by the end effect and unknown load on the system performance, and significantly improve the speed control accuracy of the permanent magnet synchronous linear motor system.

[0090] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0091] By detecting the mover position in real time, the present invention establishes a mathematical model of the permanent magnet synchronous linear motor related to the mover position, further improves the modeling accuracy of the motor movement process, and effectively optimizes the speed control performance of the motor.

[0092] By designing a disturbance equation for unmatched disturbances and combining it with a disturbance observer, the present invention realizes real-time and high-precision estimation of unmatched disturbances, and effectively improves the ability of the system to suppress external disturbances.

[0093] The present invention introduces a disturbance estimation value control strategy based on DOB observation, significantly reduces the chattering problem of the sliding mode controller, and thus improves the stability and control accuracy of the system.

[0094] By optimizing the configuration method of the gain matrix, the present invention reduces the computational amount, reduces the computational complexity while ensuring the control performance of the system, and ensures that the system can achieve the desired control effect with a smaller computational amount.

Claims

1. A control method for disturbance suppression in a permanent magnet synchronous linear motor system, characterized in that: The method includes the following steps: S1. Detect the position of the mover in real time, and establish a mathematical model of the permanent magnet synchronous linear motor related to the position of the mover; S2. Based on the mathematical model of the permanent magnet synchronous linear motor, design a disturbance observer, and use the disturbance observer to estimate in real time the end effect disturbance and load disturbance existing during the operation of the permanent magnet synchronous linear motor; S3. Based on the end effect disturbance and load disturbance estimated by the disturbance observer, construct a sliding mode controller, and use the sliding mode controller to input the end effect disturbance and load disturbance obtained by the real-time estimation of the disturbance observer into the permanent magnet synchronous linear motor system to control the speed of the permanent magnet synchronous linear motor in the permanent magnet synchronous linear motor system.

2. The control method for disturbance suppression of a permanent magnet synchronous linear motor system according to claim 1, wherein: The specific process of step S1 includes the following steps: S1.

1. Detect the position of the mover in real time, and establish the dynamic equation and q-axis voltage equation of the permanent magnet synchronous linear motor related to the position of the mover, and their expressions are: Among them, x represents the real-time position of the mover, l represents the effective length of the mover, s represents the effective length of the stator segment, ψ f represents the permanent magnet flux linkage when the mover and the stator are fully coupled, L s represents the self-inductance of the stator winding when the mover and the stator are fully coupled, L σ represents the leakage inductance of the stator winding, M represents the mass of the mover, F t represents the sum of the load resistance, magnetic resistance, and frictional force, B represents the viscous friction coefficient, R s represents the equivalent resistance of the stator, τ represents the electromagnetic pole pitch, v s represents the mover speed, u q represents the q-axis voltage of the stator, i d and i q respectively represent the d-axis current and the q-axis current, L s represents the synchronous inductance, ψ d and ψ q respectively represent the d-axis stator flux linkage and the q-axis stator flux linkage; Pn represents the number of pole pairs, ΔM represents the unknown load change, Δψ f represents the change in the permanent magnet flux linkage; S1.

2. Based on the dynamic equation and q-axis voltage equation, establish a mathematical model of the permanent magnet synchronous linear motor related to the position of the mover, and its expression is: Among them, d v represents the speed error; d i represents the q-axis current error.

3. A control method for disturbance suppression in a permanent magnet synchronous linear motor system according to claim 2, characterized in that: The specific process of step S2 includes the following steps: S2.

1. Set the unknown disturbance existing in the operation process of the permanent magnet synchronous linear motor as: where λ represents the disturbance auxiliary variable, d represents the system error matrix; both W and V represent coefficient matrices, ω represents the error frequency, and both k1 and k2 represent conversion coefficients; S2.

2. Introduce the unknown disturbance existing in the operation of the permanent magnet synchronous linear motor set in step S2.1 into the mathematical model of the permanent magnet synchronous linear motor, and obtain the mathematical model of the permanent magnet synchronous linear motor after adding the disturbance observer. Its expression is as follows: S2.

3. Transform the mathematical model of the permanent magnet synchronous linear motor after adding the disturbance observer into matrix form, specifically as follows: S2.

4. The subsystem that only contains interference items is expressed as: S2.

5. Design an interference observer according to the described subsystem. The expression of the interference observer is as follows: where x = [x1 x2] T = [v s i q T , λ represents the interference auxiliary variable, represents the estimated value of the interference auxiliary variable λ; η represents the interference auxiliary variable, E d represents the gain matrix of the interference observer, represents the estimated value of the interference auxiliary variable η; σ represents the equivalent output of the described subsystem;​ S2.

6. Use the designed disturbance observer to estimate in real time the end effect disturbance and load disturbance existing during the operation of the permanent magnet synchronous linear motor.

4. A control method for disturbance suppression in a permanent magnet synchronous linear motor system according to claim 3, characterized in that: The expression of the sliding mode controller is: where D c = cB d1 + B d2 , s represents the synovial surface, and both k and c represent adjustment parameters.

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