Current disturbance suppression method and system based on enhanced disturbance observer

Abstract

The invention discloses a current disturbance suppression method based on an enhanced disturbance observer, and the method comprises the following specific steps: firstly, taking an annular permanent magnet linear synchronous motor TPMLSM as a control object, and building a voltage mathematical model of the TPMLSM in a d-q rotating coordinate system; secondly, based on this, a current observation model containing system lumped disturbance is established, a state feedback control theory is utilized, an augmented observation error system is established, and then an enhanced disturbance observer mathematical model is deduced; finally, an enhanced disturbance observer is adopted to observe disturbance of the current closed-loop system, and feedforward compensation is carried out on the disturbance to a voltage output channel; a current closed-loop control system based on the disturbance observer is established; the invention further discloses a corresponding system, and the current tracking precision and the anti-disturbance capability of a current closed-loop system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of linear motor control, and in particular to a current disturbance suppression method and system based on an enhanced disturbance observer. Background Art

[0002] Permanent magnet linear synchronous motors (PMLSMs) are used as propulsion devices for electromagnetic launch systems due to their advantages, such as high power factor, high efficiency, and thrust density. In PMLSM drive systems, factors such as load disturbances, sensor noise, and unknown nonlinear friction can adversely affect system performance. The core goal of a PMLSM current closed-loop control system is to achieve fast response. A current closed-loop control system with excellent dynamic response characteristics can accurately track the output variable of the speed control loop, effectively increasing the bandwidth of the speed loop.

[0003] PMLSM drive systems typically employ dual closed-loop vector control technology, with conventional proportional-integral (PI) control widely used for current closed-loop control. However, as a launch motor, the PMLSM must operate under a variety of operating conditions, including acceleration and deceleration. Frequent switching between operating conditions not only degrades the drive system's dynamic performance and control accuracy, but continuous acceleration can also exacerbate system disturbances, strengthen parameter cross-coupling, and even cause speed fluctuations. Consequently, conventional PI control is difficult to achieve high-precision current regulation for the launch motor. Therefore, it is necessary to improve the tracking accuracy and disturbance rejection capabilities of the current closed-loop control system in the PMLSM drive system. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology. Aiming at the problem that the nonlinear disturbance of the system under the dynamic operation of the motor reduces the tracking accuracy and robustness of the drive system, a current disturbance suppression method and system based on an enhanced disturbance observer are proposed to improve the dynamic tracking accuracy and anti-disturbance capability of the current closed-loop control system.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a current disturbance suppression method and system based on an enhanced disturbance observer, characterized in that it includes the following steps: Step 1: Take the ring permanent magnet linear synchronous motor TPMLSM as the control object and establish the mathematical model of TPMLSM in the three-phase stationary coordinate system; based on this, establish dq Voltage state equation with system disturbance in rotating coordinate system; Step 2: q Taking the shaft current mathematical model as an example, a current observation model with disturbance and an observation error system are constructed; Step 3: Using state feedback control theory, design an augmented observation error system and then derive the enhanced disturbance observer mathematical model; Step 4: Analyze the observation performance of the designed enhanced disturbance observer to illustrate the superiority of the observer's observation capability; Step 5: Add the enhanced disturbance observer to the PI-based current closed-loop control system, build a current closed-loop control system based on the disturbance observer, and analyze the anti-disturbance capability of the current closed-loop system.

[0006] Furthermore, the mathematical equation of the TPMLSM in the three-phase stationary coordinate system in step 1 is: , In the above formula, , , are the phase voltage, current and resistance of the three-phase winding respectively; is the three-phase winding flux, φ f is the permanent magnet flux, is the electrical angle; is the three-phase winding inductance, satisfying: , in, is the stator mutual inductance, is the stator leakage inductance.

[0007] Furthermore, in the step 1 dq The stator voltage state equation containing system disturbance in the rotating coordinate system is expressed as: , In the above formula, u d 、 u q for dq Shaft stator voltage, i d , i q for dq Shaft stator voltage, L d , L q for dq Shaft inductance, R s is the stator resistance, D d and D q Respectively d Axis control channel and qThe lumped disturbance of the axis control channel includes various unknown disturbances of the system and parameter cross-coupling.

[0008] Furthermore, in step 2 q The mathematical model of the shaft channel stator current is expressed as: , in, , are defined as state variables and q Observation error of the axial lumped disturbance.

[0009] In order to derive Based on the mathematical model, a state feedback control system is designed. Among them, is defined as the system control variable, y i is the system input, y r is the system output; when y i = 0, the system disturbance can be completely compensated, that is, , the error between the system input variable and the output variable e = y i – y r It can be expressed as follows: , Furthermore, according to the above formula, the augmented observation error system is expressed as: , Where, A 0. B 0 and Z They are defined as: , , , , .

[0010] The state feedback control principle can be used to ensure the asymptotic stability of the augmented system. Therefore, the system input can be designed as: , in, , k 1 and k 2 is the feedback matrix gain.

[0011] get m The equation is: , exist Under the assumption of , the observation equation of the disturbance is finally obtained: , Perform Laplace transform on the above formula and introduce intermediate variables , the final mathematical model of the enhanced disturbance observer is: , Furthermore, in step 4, the performance of the observer is analyzed using the observer closed-loop transfer function. With actual disturbance The transfer function between Expressed as: , in, It can reflect the observation capability of the enhanced disturbance observer.

[0012] Furthermore, in the step 4, The polynomial equation is In order to ensure the stability of the observation system, The characteristic roots of s Therefore, according to the bandwidth allocation method, The characteristic root configuration is s Left half plane To ensure the stability of the system. is the bandwidth of ECDO. Therefore, satisfy: , thereby k 1 and k 2 is calculated as: , Furthermore, in step 5, the control rate of the PI-based current closed-loop control system is: , The enhanced disturbance observer is introduced into the PI-based current closed-loop control system. At this time, the transfer function of the current closed-loop control system is: , Based on this, it can be deduced that D q arrive i q The transfer function : , pass The anti-disturbance capability of the current closed-loop control system can be analyzed.

[0013] As another aspect of the present invention, it also relates to a current disturbance suppression system based on an enhanced disturbance observer, comprising: The first control unit is used to establish the mathematical model of the ring permanent magnet linear synchronous motor TPMLSM in the three-phase stationary coordinate system with the ring permanent magnet linear synchronous motor TPMLSM as the control object; based on this, the mathematical model of the ring permanent magnet linear synchronous motor TPMLSM is established. dq Voltage state equation with system disturbance in rotating coordinate system; Control unit No. 2, used to construct the current observation and observation error system containing disturbances; Control unit No. 3 uses state feedback control theory to design an augmented observation error system and construct a mathematical model of an enhanced disturbance observer; Control unit No. 4 is used to analyze the observation performance of the designed enhanced disturbance observer; The No. 5 control unit is used to add the enhanced disturbance observer to the PI-based current closed-loop control system, build a current closed-loop control system based on the disturbance observer, and analyze the anti-disturbance capability of the current closed-loop system.

[0014] The beneficial effects and features of the present invention are: (1) The present invention proposes a current disturbance suppression method and system based on an enhanced disturbance observer. An enhanced disturbance observer is proposed. By treating the concentrated disturbance as a control variable, an augmented error system is designed. At the same time, a state feedback control law is used to ensure rapid convergence of the error, thereby enhancing the observation capability of the observer.

[0015] (2) The enhanced disturbance observer-based current disturbance suppression method and system of the present invention utilizes the enhanced disturbance observer of the present invention to observe the centralized disturbance in the current control system and incorporates a disturbance feedforward compensation term into the current control system. Consequently, the current closed-loop control system based on the enhanced disturbance observer exhibits superior tracking accuracy and disturbance rejection capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a preferred embodiment of the present invention; Figure 2 This is a preferred embodiment of the annular permanent magnet linear synchronous motor structure of the present invention (wherein reference numeral 1 represents a secondary winding, and reference numeral 2 represents a primary winding); Figure 3 This is a control block diagram of an enhanced disturbance observer according to a preferred embodiment of the present invention; Figure 4 The observation performance analysis of the enhanced disturbance observer under different bandwidths in the preferred embodiment of the present invention (where (a) is the transfer function Bode curves at different bandwidths; (b) Bode curves at different bandwidths Bode curve); Figure 5 This is a block diagram of current closed-loop control based on an enhanced disturbance observer according to a preferred embodiment of the present invention; Figure 6 This is an analysis of the anti-disturbance capability of different current closed-loop control methods in the preferred embodiment of the present invention (where (a) is the anti-disturbance capability of different current closed-loop control methods under different bandwidths). Bode curve of the same bandwidth; (b) and Bode curve). DETAILED DESCRIPTION The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0017] refer to Figure 1 The embodiment of the present invention relates to a current disturbance suppression method and system based on an enhanced disturbance observer, comprising the following steps: The first step: take the ring permanent magnet linear synchronous motor TPMLSM as the control object and establish the mathematical model of TPMLSM in the three-phase stationary coordinate system; based on this, establish dq Voltage state equation with system disturbance in rotating coordinate system; Step 2: q Taking the shaft current mathematical model as an example, a current observation model with disturbance and an observation error system are constructed; Step 3: Using state feedback control theory, design an augmented observation error system and derive the enhanced disturbance observer mathematical model; Step 4: Analyze the observation performance of the designed enhanced disturbance observer to illustrate the superiority of the observer's observation capability; Step 5: Add the enhanced disturbance observer to the PI-based current closed-loop control system, build a current closed-loop control system based on the disturbance observer, and analyze the anti-disturbance capability of the current closed-loop system.

[0018] Step 6: Build a TPMLSM closed-loop vector control model and analyze the effectiveness and superiority of the control method proposed in this invention through simulation.

[0019] The topology of the transmitting motor in the specific embodiment of the present invention is as follows: Figure 2As shown. Traditional PMLSM requires a long motion stroke to accelerate the load to the target speed, which not only takes up a large space, but also increases the system cost. To this end, the present invention adopts a long primary ring permanent magnet linear synchronous motor TPMLSM. TPMLSM is a long primary permanent magnet linear synchronous motor with a ring Halbach structure. Among them, the primary winding of the motor adopts a ring concentrated winding method, and the secondary adopts a Halbach permanent magnet array. PMLSM with this structure can accelerate and brake within a given set acceleration and speed range, without being restricted by distance, and can save space and system costs.

[0020] like Figure 3 As shown in the figure, the control block diagram of the enhanced disturbance observer proposed in the present invention is provided. The model introduces an integral term, thereby enhancing the observation capability of the observer. After the enhanced disturbance observer is added to the current closed-loop control system, the concentrated disturbance can be effectively suppressed. The transfer function in the figure is, .

[0021] Figure 4 The observation performance of the enhanced disturbance observer is analyzed under different bandwidths. With actual disturbance The transfer function between Expressed as: , Furthermore, the observation error With actual disturbance The transfer function between It can be deduced as: , in, It can reflect the observation capability of the enhanced disturbance observer. It can reflect the size of ECDO observation error.

[0022] according to and , Figure 4 Bandwidth plotted The Bode curves are 300rad / s, 400rad / s, 700rad / s and 1000rad / s respectively. Figure 4 (a) is the transfer function Bode curves at different bandwidths. As can be seen from the figure, As the bandwidth increases, the system response speed increases, which shows that the observation capability of ECDO is enhanced with the increase of bandwidth. Figure 4 (b) shows the different bandwidths Bode curve of . As can be seen from the figure, as As increases, the phase delay and low-frequency gain of the Bode curve become smaller, which means that the observation error is smaller under the same disturbance input.

[0023] Figure 5 This is a block diagram of a current closed-loop control system based on an enhanced disturbance observer. The enhanced disturbance observer can observe the concentrated disturbances of the current closed-loop system and feed them into the control channel in a feedforward manner, thereby improving the current tracking capability and the anti-interference ability of the closed-loop system.

[0024] Figure 6 The Bode curves of the anti-disturbance transfer function of different current closed-loop control systems are given. for: , Figure 6 (a) shows the different bandwidths Bode curve. As can be seen from the curve in the figure, as the bandwidth ω b With the increase of , the phase delay and amplitude response in the low frequency band are reduced, which means that the anti-interference performance of the current closed-loop system is improved.

[0025] In addition, the system lumped disturbance observation model of the traditional disturbance observer is designed as: , According to the above formula, combined with the current PI control rate, the anti-disturbance transfer function of the current closed-loop control system based on the traditional disturbance observer can be derived: , Figure 6 (b) shows the same bandwidth and The Bode plot is shown. The observer bandwidth is set to 500 rad / s. The figure shows how the structural differences between the traditional disturbance observer and the enhanced disturbance observer affect the disturbance rejection capability of the current closed-loop control system. Compared to the traditional disturbance observer, the enhanced disturbance observer not only exhibits superior disturbance rejection performance in the low-frequency band but also maintains high disturbance rejection capability in the high-frequency band. These results demonstrate the superiority of the proposed observer in terms of both observation and disturbance rejection capabilities.

[0026] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A current disturbance suppression method based on an enhanced disturbance observer, characterized in that: The steps include: Step 1: Take the ring permanent magnet linear synchronous motor TPMLSM as the control object and establish the mathematical model of TPMLSM in the three-phase stationary coordinate system; based on this, establish dq Voltage state equation with system disturbance in rotating coordinate system; Step 2: Construct the current observation and observation error system containing disturbance; Step 3: Using state feedback control theory, design an augmented observation error system and construct a mathematical model of the enhanced disturbance observer; Step 4: Analyze the observation performance of the designed enhanced disturbance observer; Step 5: Add the enhanced disturbance observer to the PI-based current closed-loop control system, build a current closed-loop control system based on the disturbance observer, and analyze the anti-disturbance capability of the current closed-loop system.

2. The current disturbance suppression method based on enhanced disturbance observer according to claim 1, characterized in that: The mathematical model of the TPMLSM in the three-phase stationary coordinate system in step 1 is: ， In the above formula, , , , are the phase voltage, current and resistance of the three-phase winding respectively; is the three-phase winding flux, φ f is the permanent magnet flux, is the electrical angle; is the three-phase winding inductance, satisfying: ， in, is the stator mutual inductance, is the stator leakage inductance.

3. The current disturbance suppression method based on enhanced disturbance observer according to claim 1, characterized in that: In step one dq The stator voltage state equation containing system disturbance in the rotating coordinate system is expressed as: ， In the above formula, u d 、 u q for dq Shaft stator voltage, i d 、 i q for dq Shaft stator current, L d , L q for dq Shaft inductance, R s is the stator resistance, D d and D q Respectively d Axis control channel and q The lumped disturbance of the axis control channel includes various unknown disturbances of the system and parameter cross-coupling.

4. The current disturbance suppression method based on enhanced disturbance observer according to claim 3, characterized in that: The specific method of step 2 is: q The mathematical model of the axis channel is expressed as: , in, , , ; The current observation and observation error system with disturbance is: ， in, , are defined as state variables and q Observation error of axial lumped disturbance; Superscript ' ' represents the observed value of the corresponding parameter.

5. The current disturbance suppression method based on enhanced disturbance observer according to claim 4, characterized in that: The augmented observation error system designed using state feedback control theory in step 3 is expressed as: ， Where, A 0. B 0 and Z They are defined as: , , , , .

6. The current disturbance suppression method and system based on enhanced disturbance observer according to claim 5, Its characteristics are: The method for constructing the enhanced disturbance observer mathematical model in step 3 is: The asymptotic stability of the augmented system can be guaranteed by the state feedback control principle; therefore, the system input can be designed as: ， in, , k 1 and k 2 is the feedback matrix gain; get m The equation is: ， exist Under the assumption of , the observation equation of the disturbance is finally obtained: ， Use Laplace transform on the above formula and introduce intermediate variables , the final mathematical model of the enhanced disturbance observer is: ， Among them, 1 / s Represents an integral operation.

7. The current disturbance suppression method based on enhanced disturbance observer according to claim 6, characterized in that: The specific method of step 4 is: The performance of the observer is analyzed using the closed-loop transfer function to observe the disturbance With actual disturbance The transfer function between Expressed as: ， in, It can reflect the observation capability of the enhanced disturbance observer.

8. The current disturbance suppression method based on enhanced disturbance observer according to claim 1, characterized in that: In step 5, the control rate of the current closed-loop control system based on PI is: ， in, Defined as q Axis current tracking error, meeting e qi = i qref – i q ; i qref and i q They are q Shaft current reference and measured values; is the current loop PI control transfer function, and are proportional gain and integral gain respectively.

9. The current disturbance suppression method based on enhanced disturbance observer according to claim 8, characterized in that: In step 5, the enhanced disturbance observer is introduced into the PI-based current closed-loop control system. At this time, the transfer function of the current closed-loop control system is: ， Based on this, it can be deduced that D q arrive i q The transfer function : ， pass The anti-disturbance capability of the current closed-loop control system can be analyzed.

10. A current disturbance suppression system based on an enhanced disturbance observer, characterized in that: include: The first control unit is used to establish the mathematical model of the ring permanent magnet linear synchronous motor TPMLSM in the three-phase stationary coordinate system with the ring permanent magnet linear synchronous motor TPMLSM as the control object; based on this, the mathematical model of the ring permanent magnet linear synchronous motor TPMLSM is established. dq Voltage state equation with system disturbance in rotating coordinate system; Control unit No. 2, used to construct the current observation and observation error system containing disturbances; Control unit No. 3 uses state feedback control theory to design an augmented observation error system and construct a mathematical model of an enhanced disturbance observer; Control unit No. 4 is used to analyze the observation performance of the designed enhanced disturbance observer; The No. 5 control unit is used to add the enhanced disturbance observer to the PI-based current closed-loop control system, build a current closed-loop control system based on the disturbance observer, and analyze the anti-disturbance capability of the current closed-loop system.

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