Converter single-loop control method, system and equipment based on all-drive system model

Abstract

The invention discloses a converter single-loop control method, system and equipment based on an all-drive system model, and belongs to the field of power systems, and the method comprises the steps: carrying out the coordinate transformation of the three-phase voltage and current of a converter and the output voltage of the last moment, and obtaining the two-phase voltage and current, the component of the two-phase output voltage on the d axis is determined as a first output voltage; performing estimation value calculation on the two-phase voltage, the two-phase current and the first output voltage based on the observation parameters, and driving an estimation error to converge to a zero value within a preset time through an observer so as to obtain a disturbance estimation value and a state estimation value of the converter; the disturbance estimation value and the state estimation value are calculated based on the control parameters of the controller established by the all-drive system model to obtain the current voltage, and the control signal is determined according to the current voltage to perform single-loop control on the three-phase converter, so that the disturbance suppression capability of the converter can be improved, and the stable operation of the converter is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power systems, in particular to a converter single-loop control method, system and device based on a full-drive system model. BACKGROUND

[0002] New energy vehicle charger construction has become a key direction of "new infrastructure construction". The three-phase PWM converter has the advantages of bidirectional energy flow, adjustable input power factor and sinusoidal grid current, and has become the core component of the front-end rectifier of the electric vehicle bidirectional charger. The main control target is to maintain the stability of the DC side voltage, realize the sinusoidal grid current and power regulation, so as to ensure the charging safety of the DC side battery.

[0003] However, the three-phase PWM converter is a multivariable, strongly coupled nonlinear system, and its control performance is easily affected by system uncertainty factors (such as parameter fluctuation, load disturbance, and grid disturbance), which may endanger the safe operation of the system. In order to maintain the stability of the DC voltage, various control schemes have been formed in the prior art, mainly including: a fixed time command filter control method, which constructs a fixed time controller for the voltage loop and the power loop, combines a command filter to process the derivative of the power reference value, and realizes the modulation of the control input, but the active suppression ability of this scheme to high-frequency switching noise or grid harmonic interference is limited, which may cause distortion of the power loop modulation voltage; and a high-disturbance backstepping control method, which estimates the equivalent disturbance based on a disturbance observer and designs a backstepping control law with disturbance compensation, but the observer bandwidth is fixed, which may cause estimation lag of high-frequency interference and affect the dynamic disturbance rejection performance. Moreover, the above prior art generally adopts a double-loop cascaded structure of "voltage outer loop + current / power inner loop", which has the problems of complex control structure, increased design difficulty, high calculation demand and high hardware cost, and in order to realize the decoupling of the inner and outer loops, the outer loop parameters are usually conservative, resulting in slow dynamic response of the DC voltage. SUMMARY

[0004] The present application provides a converter single-loop control method, system and device based on a full-drive system model, which can solve the problem of insufficient disturbance suppression ability of the existing control method.

[0005] The present application provides a converter single-loop control method based on a full-drive system model, comprising: obtaining the three-phase grid voltage and the three-phase grid current of the three-phase converter at the current time, and the output voltage of the three-phase converter at the previous time, performing synchronous rotating coordinate system transformation on the three-phase grid voltage, the three-phase grid current and the output voltage to obtain two-phase grid voltage, two-phase grid current and two-phase output voltage, and determining the component of the two-phase output voltage on the d-axis as a first output voltage; The estimated values ​​of the two-phase grid voltage, the two-phase grid current and the first output voltage are calculated based on the observation parameters of the disturbance observer, and the estimation error is driven to converge to zero within a preset time by the disturbance observer to obtain the lumped disturbance estimate and state estimate of the three-phase converter. The lumped disturbance includes load disturbance and parameter uncertainty disturbance. The disturbance estimate and the state estimate are calculated based on the control parameters of the state feedback controller to obtain the current output voltage. The control signal is determined based on the current output voltage, and the three-phase converter is controlled in a single loop based on the control signal. The state feedback controller is established based on the full drive system model, and the control parameters are determined based on the stability conditions of the full drive system model.

[0006] This invention simplifies the control process and reduces engineering implementation difficulty by designing a single-loop control structure for a three-phase converter. Through synchronous rotating coordinate system transformation, the three-phase AC quantities are converted into DC quantities in a two-phase rotating coordinate system, providing a unified calculation basis for subsequent observation and control. Using a finite-time disturbance observer, rapid estimation of lumped disturbances (load disturbances + parameter uncertainties) and system state is achieved, with the estimation error converging to zero within a preset time, improving the system's disturbance suppression capability. The state feedback controller designed based on the full-drive system model, combined with control parameters determined by stability conditions, ensures the stability of the closed-loop system and achieves rapid and accurate control of the converter's DC voltage.

[0007] Furthermore, the estimated values ​​of the two-phase grid voltage, the two-phase grid current, and the first output voltage are calculated based on the observation parameters of the disturbance observer, and the estimation error is driven to converge to zero within a preset time by the disturbance observer, specifically as follows: ; in, yes The estimated value, It is an estimation error, and Observer parameters , , , It is a filter inductor. It is a DC-side capacitor. It is the angular frequency of the three-phase grid voltage. and It is a two-phase grid current. and It is a two-phase grid voltage. It is the first output voltage. and These are the first state variable and the second state variable, respectively. It is a state error variable constructed based on DC voltage. yes The first derivative variable, It is a lumped disturbance. and These are the estimates for the first state and the estimates for the second state, respectively.

[0008] By clearly defining the specific computational logic of the finite-time disturbance observer and setting the observation parameters, the accuracy of the state estimate and the lumped disturbance estimate is ensured. The estimation error is driven to converge to zero within a finite time, which guarantees the observer's rapid response to dynamic changes in the system. This provides the controller with real-time and reliable input information and enhances the system's adaptability to complex operating conditions.

[0009] Furthermore, determining the control signal based on the current output voltage specifically involves: The second output voltage corresponding to the voltage component on the q-axis in the proportional and integral control loop of the state feedback controller is obtained. The second output voltage and the current output voltage are synchronously rotated to obtain the target voltage. A control signal is generated based on the target voltage to control the three-phase converter.

[0010] In this way, the q-axis voltage component (second output voltage) is generated through the proportional-integral control loop, and coordinated with the current output voltage on the d-axis to achieve coordinated regulation of active and reactive power. The target voltage is obtained through synchronous rotating coordinate system transformation, which ensures the accurate generation of the three-phase output voltage, provides accurate input for PWM modulation, reduces voltage distortion, and improves the sinusoidal nature of the grid current.

[0011] Furthermore, the current output voltage is obtained by calculating the disturbance estimate and the state estimate based on the control parameters of the state feedback controller, specifically as follows: ; in, and These are all the control parameters of the state feedback controller. It is a filter inductor. It is a DC-side capacitor. It is the angular frequency of the three-phase grid voltage. and It is a two-phase grid current. and It is a two-phase grid voltage. It is the first output voltage. and All are state error variables. It is a state error variable constructed based on DC voltage. yes The first derivative variable, It is a lumped disturbance.

[0012] This clarifies the current output voltage (d-axis voltage u). d The specific calculation formula is directly calculated based on the state feedback controller parameters and observer estimates, ensuring the real-time performance and accuracy of the control quantity. This calculation process directly reflects the compensation for lumped disturbances and the correction of state errors, realizing rapid adjustment of DC voltage and improving voltage tracking accuracy.

[0013] Furthermore, the estimation error is driven to converge to zero within a preset time by the perturbation observer, wherein the estimation error includes state error and perturbation error, specifically: The error equation is determined based on the rate of change of the state error and the rate of change of the disturbance error. The observation parameters are determined by converging the error equation to zero within a finite time.

[0014] By constructing the error equation, the correlation between the observer parameters and error convergence is clarified; this ensures that the error dynamic equation converges to zero within a finite time, providing a clear basis for the selection of observation parameters, guaranteeing the efficient operation of the perturbation observer, and further improving the estimation accuracy and convergence speed.

[0015] Furthermore, the error equation is specifically as follows: The state error includes a first error and a second error. For the first error, This is the second error. The disturbance error is denoted as .

[0016] This provides the specific form of the error dynamic equation. By introducing a sign function and a power term, the finite-time convergence characteristic of the estimation error is mathematically guaranteed. The equation directly reflects the evolution of the error, ensuring that the observer's estimation of disturbances and states is fast and accurate, and providing theoretical support for the system's disturbance rejection performance.

[0017] Furthermore, the state feedback controller is established based on the all-drive system model, and the control parameters are determined based on the stability conditions of the all-drive system model, specifically: The stability formula of the state feedback controller is determined based on the all-drive system model, and the characteristic equation of the state feedback controller is determined based on the stability formula. When multiple eigenvalues ​​corresponding to the characteristic equation all have negative real parts, the state feedback controller, the disturbance observer, and the three-phase converter meet the stability condition and output the respective control parameters.

[0018] By clarifying the specific logic of the state feedback controller based on the all-drive system model, and deriving it through stability formulas and characteristic equations, a quantitative basis for the design of control parameters is provided. Based on the stability condition that all eigenvalues ​​have negative real parts, the stable operation of the closed-loop system composed of the controller, observer, and converter is ensured, avoiding system oscillation or instability.

[0019] Furthermore, the all-drive system model is specifically as follows: ; in, It is a lumped disturbance; The stability formula is as follows: ; The characteristic equation is, .

[0020] By clarifying the specific expression of the all-drive system model, load disturbances and parameter uncertainties are integrated into a lumped disturbance z3(t), providing a concise and unified mathematical model for control strategy design. The specific forms of the stability formula and characteristic equation are given, the conditions for system stability are quantified, and a direct mathematical tool is provided for the tuning of controller parameters, ensuring the scientific nature and effectiveness of the control strategy.

[0021] Another embodiment of the present invention provides a converter single-loop control system based on a full-drive system model, including: an acquisition module, an estimation module and a control module; The acquisition module is used to acquire the three-phase grid voltage and three-phase grid current of the three-phase converter at the current moment, as well as the output voltage of the three-phase converter at the previous moment. It performs synchronous rotating coordinate system transformation on the three-phase grid voltage, the three-phase grid current, and the output voltage to obtain two-phase grid voltage, two-phase grid current, and two-phase output voltage, respectively, and determines the component of the two-phase output voltage on the d-coordinate axis as the first output voltage. The estimation module is used to calculate the estimated values ​​of the two-phase grid voltage, the two-phase grid current and the first output voltage based on the observation parameters of the disturbance observer, and drive the estimation error to converge to zero within a preset time through the disturbance observer, so as to obtain the lumped disturbance estimate and the state estimate of the three-phase converter, wherein the lumped disturbance includes load disturbance and parameter uncertainty disturbance; The control module is used to calculate the disturbance estimate and the state estimate based on the control parameters of the state feedback controller to obtain the current output voltage, determine the control signal based on the current output voltage, and perform single-loop control on the three-phase converter based on the control signal. The state feedback controller is established based on the full drive system model, and the control parameters are determined based on the stability conditions of the full drive system model.

[0022] This invention simplifies the control process and reduces engineering implementation difficulty by designing a single-loop control structure for a three-phase converter. Through synchronous rotating coordinate system transformation, the three-phase AC quantities are converted into DC quantities in a two-phase rotating coordinate system, providing a unified calculation basis for subsequent observation and control. Using a finite-time disturbance observer, rapid estimation of lumped disturbances (load disturbances + parameter uncertainties) and system state is achieved, with the estimation error converging to zero within a preset time, improving the system's disturbance suppression capability. The state feedback controller designed based on the full-drive system model, combined with control parameters determined by stability conditions, ensures the stability of the closed-loop system and achieves rapid and accurate control of the converter's DC voltage.

[0023] Another embodiment of the present invention provides a terminal device, including: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the steps of the converter single-loop control method based on the all-drive system model of the present invention. Attached Figure Description

[0024] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a flowchart illustrating a converter single-loop control method based on a full-drive system model provided in an embodiment of the present invention. Figure 2 This is a flowchart illustrating another converter single-loop control method based on a full-drive system model provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the DC voltage response when the DC voltage is adjusted from 350V to 400V according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the grid current response when the DC voltage is adjusted from 350V to 400V according to an embodiment of the present invention; Figure 5This is a schematic diagram of the DC voltage response when the load changes from 100Ω to 50Ω according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the grid current response when the load changes from 100Ω to 50Ω according to an embodiment of the present invention; Figure 7 This is a schematic diagram of another converter single-loop control system based on a full-drive system model provided in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0028] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0031] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0032] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0033] See Figure 1 To address the problem of insufficient disturbance suppression capability of existing control methods in the prior art, an embodiment of the present invention provides a converter single-loop control method based on a full-drive system model, comprising: Step S101: Obtain the three-phase grid voltage and three-phase grid current of the three-phase converter at the current moment, and the output voltage of the three-phase converter at the previous moment. Perform synchronous rotating coordinate system transformation on the three-phase grid voltage, the three-phase grid current and the output voltage to obtain the two-phase grid voltage, the two-phase grid current and the two-phase output voltage respectively. Determine the component of the two-phase output voltage on the d coordinate axis as the first output voltage.

[0034] Among them, the synchronous rotating coordinate system transformation (Park coordinate transformation) transforms three-phase AC quantities from a stationary coordinate system (such as the abc coordinate system) to a coordinate system that rotates synchronously with the power supply angular frequency (such as the dq coordinate system), thereby simplifying the analysis and control of AC signals.

[0035] In this embodiment, three-phase voltage transformers (PTs) and three-phase current transformers (CTs) are installed on the grid-connected side of the converter to collect the three-phase grid voltage on the grid side in real time. and three-phase power grid current Simultaneously, the three-phase output voltage of the converter calculated in the previous control cycle is retrieved from the controller's memory of the previous time step. A digital phase-locked loop (PLL) is used to lock the position of the grid voltage vector in real time, obtaining the synchronous rotation angle θ. The sampled three-phase grid voltages are then analyzed. Three-phase power grid current and the output voltage at the previous moment Performing Park transformation (synchronous rotating coordinate transformation) at the same θ angle: converting three-phase grid voltage into two-phase voltage in the dq coordinate system. Three-phase grid current converted to two-phase current in dq coordinate system The three-phase output voltage at the previous moment is converted to the two-phase output voltage in the dq coordinate system. and Take the components of the transformed two-phase output voltage vectors on the d-axis. This serves as the first output voltage, which is then directly used by the disturbance observer and the state feedback controller.

[0036] Step S102: Based on the observation parameters of the disturbance observer, the estimated values ​​of the two-phase grid voltage, the two-phase grid current and the first output voltage are calculated, and the estimation error is driven to converge to zero within a preset time by the disturbance observer to obtain the lumped disturbance estimate and state estimate of the three-phase converter, wherein the lumped disturbance includes load disturbance and parameter uncertainty disturbance.

[0037] Lyapunov is used to determine whether a dynamic system can return to equilibrium after being disturbed, and whether it is stable.

[0038] In this embodiment, the system lumped disturbance is required to construct the state feedback controller. and system status The information. However, the lumped disturbance of the system. and state The unknown and uncertain nature of disturbances affects controller design and burdens controller computation. Therefore, this invention introduces a finite-time disturbance observer into the three-phase PWM converter to estimate lumped disturbances and system state in real time. This enhances the disturbance suppression performance of the three-phase PWM converter system. Specifically, in the dq coordinate system, measurable... , and what was obtained in the previous moment As input, all uncertainties, such as load changes and inductance / capacitance / resistance parameter drift, are treated as a single "lumped disturbance" d. The observer internally has two estimation channels: a state channel for real-time estimation of the DC bus voltage. and its first derivative The perturbation channel is used for real-time estimation of the lumped perturbation d. Observation parameters. The system is tuned offline according to finite-time stability conditions to ensure that the dynamic equation of the estimation error theoretically converges to zero within a preset time T. At each control node, the currently measured two-phase grid voltage, two-phase current, and first output voltage are fed into the observer; the observer internally utilizes the pre-tuned observation parameters. , for state and aggregate disturbance Perform recursive updates; output the latest state estimate. , and lumped disturbance estimate This is for direct use by the next step, the state feedback controller. Because... The offline design has been verified using the Lyapunov finite-time stability criterion. Under any operating condition, the observer can guarantee that the norm of the estimation error e monotonically decreases to zero within a preset time T. In other words, the estimation error will not oscillate indefinitely, nor will a steady-state residual appear, thus ensuring the lumped disturbance estimate. With real disturbance When they completely overlap within a finite time, the state estimates also converge synchronously.

[0039] As an example of an embodiment of the present invention, the estimated values ​​of the two-phase grid voltage, the two-phase grid current, and the first output voltage are calculated based on the observation parameters of the disturbance observer, and the estimation error is driven to converge to zero within a preset time by the disturbance observer, specifically as follows: ; in, yes The estimated value, It is an estimation error, and Observer parameters , , , It is a filter inductor. It is a DC-side capacitor. It is the angular frequency of the three-phase grid voltage. and It is a two-phase grid current. and It is a two-phase grid voltage. It is the first output voltage. and These are the first state variable and the second state variable, respectively. It is a state error variable constructed based on DC voltage. yes The first derivative variable, It is a lumped disturbance. and These are the estimates for the first state and the estimates for the second state, respectively.

[0040] As an example of an embodiment of the present invention, the estimation error is driven to converge to zero within a preset time by the perturbation observer, wherein the estimation error includes state error and perturbation error, specifically: The error equation is determined based on the rate of change of the state error and the rate of change of the disturbance error. The observation parameters are determined by converging the error equation to zero within a finite time.

[0041] In this embodiment, the state error refers to the difference between the actual state and the estimated state, and the disturbance error refers to the difference between the actual disturbance and the estimated disturbance value, thus obtaining the estimation error. , , The rate of change of the state error can be obtained by differentiating the state error, and the rate of change of the disturbance error can be obtained by differentiating the disturbance error. Based on the rates of change of the state error and the disturbance error, an error equation is established. To ensure that the error equation converges to zero in a finite time, a suitable Lyapunov function V is chosen to analyze the stability of the error dynamic equation, and the time derivative of V is calculated. In order to make To converge to zero within a finite time, appropriate observation parameters need to be selected. , making It is negative definite. For example, it can be taken as... , , To ensure It is a negative constant.

[0042] As an example of an embodiment of the present invention, the error equation is specifically as follows: ; The state error includes a first error and a second error. For the first error, This is the second error. The disturbance error is denoted as .

[0043] Step S103: Calculate the disturbance estimate and the state estimate based on the control parameters of the state feedback controller to obtain the current output voltage. Determine the control signal based on the current output voltage and perform single-loop control on the three-phase converter based on the control signal. The state feedback controller is established based on the full drive system model, and the control parameters are determined based on the stability conditions of the full drive system model.

[0044] In this embodiment, the estimated disturbance and estimated state are fed into a single-loop state feedback controller at once, directly calculating the converter output voltage that should be applied and immediately converting it into a PWM switching signal. The entire closed loop has only this one level of control, without any outer-inner loop nesting, hence the term "single-loop." Specifically, the state feedback controller is based on a full-drive system model, which describes the dynamic behavior of the three-phase PWM converter as a set of state equations, comprehensively considering load disturbances and parameter uncertainties. The controller's design goal is to achieve fast and accurate DC voltage control using state feedback. The lumped disturbance estimate and state estimate obtained from the disturbance observer are input into the state feedback controller. Based on the full-drive system model, the control law of the state feedback controller is designed. The control law can be expressed as: ; in, and These control parameters are determined based on the stability conditions of the all-drive system model. The selection of these parameters ensures that the eigenvalues ​​of the closed-loop system have negative real parts, thereby guaranteeing the stability of the system.

[0045] At each control node time, the state estimate sent by the disturbance observer is... and and disturbance estimates Substituting the values ​​into the state feedback law, we obtain the current output voltage ud along the d-axis in the dq coordinate system at the current control node. This formula completes "state error correction + disturbance feedforward compensation" in one step, without needing to go through a current loop or other inner loops. We then obtain the current output voltage uq along the q-axis in the dq coordinate system at the current control node, and generate a modulation signal based on ud and uqc to control the converter. Furthermore, the estimated values ​​during the dynamic stabilization process are also input into the feedback controller, and ud is then calculated according to the control formula.

[0046] As an example of an embodiment of the present invention, determining the control signal based on the current output voltage specifically includes: The second output voltage corresponding to the voltage component on the q-axis in the proportional and integral control loop of the state feedback controller is obtained. The second output voltage and the current output voltage are synchronously rotated to obtain the target voltage. A control signal is generated based on the target voltage to control the three-phase converter.

[0047] In this embodiment, the q-axis component uq in the dq coordinate system at the current control node time is obtained through the pi element. A dq / abc inverse transform is performed on ud and uq to obtain the three-phase modulated voltage. This voltage is then converted into the duty cycle signal of the switching transistor using a general-purpose PWM method (such as space vector modulation SVPWM or carrier comparison method); this duty cycle signal is the control signal. The control signal directly drives the three-phase inverter bridge, completing one single-loop control cycle. The entire process has no cascaded loops, single parameters, and is simple to implement.

[0048] As an example of an embodiment of the present invention, the calculation of the disturbance estimate and the state estimate based on the control parameters of the state feedback controller to obtain the current output voltage is specifically as follows: ; in, and These are all the control parameters of the state feedback controller. It is a filter inductor. It is a DC-side capacitor. It is the angular frequency of the three-phase grid voltage. and It is a two-phase grid current. and It is a two-phase grid voltage. It is the first output voltage. and All are state error variables. It is a state error variable constructed based on DC voltage. yes The first derivative variable, It is a lumped disturbance.

[0049] As an example of an embodiment of the present invention, the all-drive system model is specifically as follows: ; in, It is a lumped disturbance; The stability formula is as follows: ; The characteristic equation is, .

[0050] In this embodiment, based on the working principle of the three-phase PWM converter, the law of power conservation, and instantaneous power theory, the dynamic mathematical model of the DC side of the three-phase PWM converter is as follows: ; Among them, the dynamic mathematical model of the DC side is used to describe the dynamic characteristics of the system and is the basis for deriving the full drive system model. The full drive system model is the basis for designing the controller. This is the measured value of the DC voltage. It is a DC-side capacitor. It is the load resistance. Applying Kirchhoff's voltage law and through Park coordinate transformation, the dynamic mathematical model of the AC measurement on the dq axis is obtained as follows: (2); (3); in, It is a filter inductor. It is the equivalent resistance of the line. It is the angular frequency of the three-phase voltage.

[0051] In the original dynamic mathematical models (1) and (2) for the DC and AC sides mentioned above, the load disturbance related terms are: The term appearing in formula (1) represents a mismatched disturbance; the parameter uncertainty term is... The variable appearing in formula (2) is a matched perturbation. A new state variable is defined. and Subsequently, in the established full-drive system model, the lumped disturbance Includes load disturbance and unknown parameters The information provided is a matched disturbance. In summary, the load disturbance and the uncertainty of system parameters are integrated into a matched lumped disturbance in the established full-drive system model. .

[0052] In equations (1) and (3), the original dynamic mathematical model of DC voltage control of a three-phase PWM converter is a nonlinear system with mismatched load disturbance and parameter uncertainty.

[0053] In this invention, DC voltage is defined. Related new dynamic values .right Taking the derivative, the dynamic mathematical model of the DC side of the three-phase PWM converter can be written as: (4); Secondly, define system variables. and ,in yes Reference value, This is a reference value for DC voltage.

[0054] Then, to and Differentiation yields: (5); in, It is an unknown lumped disturbance caused by load disturbance and parameter uncertainty.

[0055] According to formula (5), the full drive system model for regulating the DC voltage of the three-phase PWM converter is obtained as follows: (6); In electric vehicle charging systems, the control objective of a three-phase PWM converter is to make the DC voltage... Track its reference value This is crucial for maintaining the charging safety of the DC-side battery.

[0056] As an example of an embodiment of the present invention, the state feedback controller is established based on an all-drive system model, and the control parameters are determined based on the stability conditions of the all-drive system model, specifically: Based on the all-drive system model, the stability formula of the state feedback controller is determined, and based on the stability formula, the characteristic equation of the state feedback controller is determined. When multiple eigenvalues ​​corresponding to the characteristic equation all have negative real parts, the state feedback controller, the disturbance observer, and the three-phase converter meet the stability condition, and output the control parameters.

[0057] In this embodiment, during the stability analysis of the closed-loop system including the observer, controller, and converter, the control parameters a and b of the controller are determined. Specifically, the control formula used to calculate ud in the controller is substituted into the full drive system model (i.e., formula (6)) to obtain the stability formula: (7); In the finite-time perturbation observer, we obtain the estimation error. It converges to zero in a finite time. After a finite-time transient phase, the closed-loop system can be represented as follows: (8); Based on modern control theory, if we choose appropriate controller parameters a and b such that the eigenvalues ​​of the closed-loop system have negative real parts, then the closed-loop system is stable, i.e. It tends towards zero. The characteristic equation can be represented as follows: (9); The eigenvalues ​​(also known as closed-loop poles) of a closed-loop system are an important concept in control system theory, used to analyze the stability of the system. In particular, if all eigenvalues ​​have negative real parts, the closed-loop system is stable.

[0058] Based on the above analysis, the single-loop state feedback controller designed in this invention uses lumped disturbance estimates to counteract the effects of lumped disturbances, thereby obtaining a linear time-invariant closed-loop control system with a configurable characteristic structure. This demonstrates that the designed single-loop state feedback controller has good disturbance rejection capability and can achieve fast and accurate DC voltage control performance.

[0059] It should be noted that the above formulas (7)-(9) are only used to analyze the stability of the closed-loop system and are not used in the calculation of the controller.

[0060] As another example of an embodiment of the present invention, such as Figure 2 As shown, the three-phase PWM converter control strategy based on the theory of all-drive systems mainly consists of two parts: a finite-time disturbance observer and a state feedback controller designed for the all-drive system. The finite-time disturbance observer accurately estimates the system's state and lumped disturbances, and directly compensates for them to the controller. The outputs of the state feedback controller and the PI controller... and Transform into , and Then, a modulation wave is generated through PWM modulation to control the converter.

[0061] To further illustrate the effectiveness of the proposed single-loop control method for a three-phase PWM converter based on the theory of all-drive systems, a system simulation model was built in Matlab / Simulink for simulation studies. Main circuit parameter settings: three-phase grid voltage amplitude 110V, filter inductance L=3mH, line equivalent resistance R=0.3Ω, load resistance... The three-phase angular frequency is DC side capacitor Switching frequency The DC voltage reference value is set to 330V.

[0062] The proposed control method was tested under load disturbances, specifically as follows: Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown. Specifically, in At that time, the DC voltage reference value was adjusted from 350V to 400V. Subsequently, Seconds, load from Change to To assess robustness to load disturbances.

[0063] Simulation results show that when the DC voltage reference value of the three-phase PWM converter changes or there is a large load disturbance, the proposed strategy successfully restores the DC voltage to its reference value, demonstrating good disturbance suppression capability. In this case, the steady-state time and overshoot of the DC voltage are respectively... and As the load increases, the grid current increases accordingly and stabilizes into a sinusoidal waveform after a certain period. The proposed strategy not only demonstrates excellent steady-state performance but also maintains a fast response under dynamic conditions. Transient effects caused by load disturbances are suppressed in a short time, and the voltage quickly recovers to the reference value. Furthermore, the rapid voltage regulation enables the system to adjust quickly to cope with significant changes in the reference value, ensuring the power quality on the DC side and the stability of the overall system.

[0064] like Figure 7 As shown, based on the above method embodiments, corresponding system embodiments are provided; One embodiment of the present invention provides a converter single-loop control system 700 based on a full drive system model, including: an acquisition module 701, an estimation module 702 and a control module 703; The acquisition module 701 is used to acquire the three-phase grid voltage and three-phase grid current of the three-phase converter at the current moment, and the output voltage of the three-phase converter at the previous moment. It performs synchronous rotating coordinate system transformation on the three-phase grid voltage, the three-phase grid current and the output voltage to obtain two-phase grid voltage, two-phase grid current and two-phase output voltage respectively, and determines the component of the two-phase output voltage on the d coordinate axis as the first output voltage. The estimation module 702 is used to calculate the estimated values ​​of the two-phase grid voltage, the two-phase grid current and the first output voltage based on the observation parameters of the disturbance observer, and drive the estimation error to converge to zero within a preset time through the disturbance observer, so as to obtain the lumped disturbance estimate and the state estimate of the three-phase converter, wherein the lumped disturbance includes load disturbance and parameter uncertainty disturbance; The control module 703 is used to calculate the disturbance estimate and the state estimate based on the control parameters of the state feedback controller to obtain the current output voltage, determine the control signal based on the current output voltage, and perform single-loop control on the three-phase converter based on the control signal. The state feedback controller is established based on the full drive system model, and the control parameters are determined based on the stability conditions of the full drive system model.

[0065] It is understood that the above system item embodiments correspond to the method item embodiments of the present invention, and can realize the converter single-loop control method based on the all-drive system model provided by any of the above method item embodiments of the present invention.

[0066] It should be noted that the system embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the system embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0067] Based on the above embodiments of the converter single-loop control method based on the all-drive system model, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the converter single-loop control method based on the all-drive system model of any embodiment of the present invention.

[0068] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0069] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0070] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0071] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the converter single-loop control method based on the all-drive system model described in any of the above-described method embodiments of the present invention.

[0072] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0073] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A converter single-loop control method based on a full-drive system model, characterized in that, include: The three-phase grid voltage and three-phase grid current of the three-phase converter at the current moment, and the output voltage of the three-phase converter at the previous moment are obtained. The three-phase grid voltage, the three-phase grid current and the output voltage are synchronously rotated and transformed to obtain two-phase grid voltage, two-phase grid current and two-phase output voltage respectively. The component of the two-phase output voltage on the d coordinate axis is determined as the first output voltage. The estimated values ​​of the two-phase grid voltage, the two-phase grid current and the first output voltage are calculated based on the observation parameters of the disturbance observer, and the estimation error is driven to converge to zero within a preset time by the disturbance observer to obtain the lumped disturbance estimate and state estimate of the three-phase converter. The lumped disturbance includes load disturbance and parameter uncertainty disturbance. The disturbance estimate and the state estimate are calculated based on the control parameters of the state feedback controller to obtain the current output voltage. The control signal is determined based on the current output voltage, and the three-phase converter is controlled in a single loop based on the control signal. The state feedback controller is established based on the full drive system model, and the control parameters are determined based on the stability conditions of the full drive system model.

2. The converter single-loop control method based on the all-drive system model as described in claim 1, characterized in that, The estimated values ​​of the two-phase grid voltage, the two-phase grid current, and the first output voltage are calculated based on the observation parameters of the disturbance observer, and the estimation error is driven to converge to zero within a preset time by the disturbance observer. Specifically: in, yes The estimated value, It is an estimation error, and Observer parameters , , , It is a filter inductor. It is a DC-side capacitor. It is the angular frequency of the three-phase grid voltage. and It is a two-phase grid current. and It is a two-phase grid voltage. It is the first output voltage. and These are the first state variable and the second state variable, respectively. It is a state error variable constructed based on DC voltage. yes The first derivative variable, It is a lumped disturbance. and These are the estimates for the first state and the estimates for the second state, respectively.

3. The converter single-loop control method based on the all-drive system model as described in claim 1, characterized in that, The step of determining the control signal based on the current output voltage specifically involves: The second output voltage corresponding to the voltage component on the q-axis in the proportional and integral control loop of the state feedback controller is obtained. The second output voltage and the current output voltage are synchronously rotated to obtain the target voltage. A control signal is generated based on the target voltage to control the three-phase converter.

4. The converter single-loop control method based on the all-drive system model as described in claim 1, characterized in that, The control parameters based on the state feedback controller are used to calculate the disturbance estimate and the state estimate to obtain the current output voltage, specifically: ; in, and These are all the control parameters of the state feedback controller. It is a filter inductor. It is a DC-side capacitor. It is the angular frequency of the three-phase grid voltage. and It is a two-phase grid current. and It is a two-phase grid voltage. It is the first output voltage. and All are state error variables. It is a state error variable constructed based on DC voltage. yes The first derivative variable, It is a lumped disturbance.

5. The converter single-loop control method based on the all-drive system model as described in claim 2, characterized in that, The estimation error is driven to converge to zero within a preset time by the perturbation observer, wherein the estimation error includes state error and perturbation error, specifically: The error equation is determined based on the rate of change of the state error and the rate of change of the disturbance error. The observation parameters are determined by converging the error equation to zero within a finite time.

6. The converter single-loop control method based on the all-drive system model as described in claim 5, characterized in that, The error equation is as follows: The state error includes a first error and a second error. For the first error, This is the second error. The disturbance error is denoted as .

7. The converter single-loop control method based on the all-drive system model as described in claim 1, characterized in that, The state feedback controller is established based on the all-drive system model, and the control parameters are determined based on the stability conditions of the all-drive system model, specifically: The stability formula of the state feedback controller is determined based on the all-drive system model, and the characteristic equation of the state feedback controller is determined based on the stability formula. When multiple eigenvalues ​​corresponding to the characteristic equation all have negative real parts, the state feedback controller, the disturbance observer, and the three-phase converter meet the stability condition and output the respective control parameters.

8. The converter single-loop control method based on the all-drive system model as described in claim 7, characterized in that, The all-drive system model is specifically as follows: ; in, It is a lumped disturbance; The stability formula is as follows: ; The characteristic equation is, .

9. A converter single-loop control system based on a full-drive system model, characterized in that, include: Acquisition module, estimation module, and control module; The acquisition module is used to acquire the three-phase grid voltage and three-phase grid current of the three-phase converter at the current moment, as well as the output voltage of the three-phase converter at the previous moment. It performs synchronous rotating coordinate system transformation on the three-phase grid voltage, the three-phase grid current, and the output voltage to obtain two-phase grid voltage, two-phase grid current, and two-phase output voltage, respectively, and determines the component of the two-phase output voltage on the d-coordinate axis as the first output voltage. The estimation module is used to calculate the estimated values ​​of the two-phase grid voltage, the two-phase grid current and the first output voltage based on the observation parameters of the disturbance observer, and drive the estimation error to converge to zero within a preset time through the disturbance observer, so as to obtain the lumped disturbance estimate and the state estimate of the three-phase converter, wherein the lumped disturbance includes load disturbance and parameter uncertainty disturbance; The control module is used to calculate the disturbance estimate and the state estimate based on the control parameters of the state feedback controller to obtain the current output voltage, determine the control signal based on the current output voltage, and perform single-loop control on the three-phase converter based on the control signal. The state feedback controller is established based on the full drive system model, and the control parameters are determined based on the stability conditions of the full drive system model.

10. A terminal device, characterized in that, The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the converter single-loop control method based on the all-drive system model as described in any one of claims 1-8.

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