A method and system for LADRC control based on DAB converter

Abstract

The application discloses a kind of LADRC control methods based on DAB converter, comprising: with the unit value of transmission power as control quantity, LADRC control is carried out through DAB converter linear large signal model;Wherein, the DAB converter linear large signal model is based on single-sided asymmetric duty cycle modulation method, and the control of output voltage is realized by directly controlling quantized transmission power.The control method proposed in the application improves the traditional linear active disturbance rejection controller under the premise of guaranteeing system performance, and optimizes the parameter setting process.Finally, it is verified through a simulation platform, and the overall efficiency in the full power range is significantly improved.The control proposed has better robustness than the traditional PI control, and greatly simplifies the problem of too many parameters and difficult to value in the design of traditional ADRC controller.

Description

Technical Field

[0001] This invention relates to the field of signal modulation technology, and in particular to a LADRC control method and system based on a DAB converter. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Single-phase phase-shift (SPS) modulation is the simplest modulation method for DAB converters, adjusting the magnitude and direction of transmitted power by controlling the phase shift angle between the two H-bridges. However, when the input and output voltage amplitudes are mismatched, soft switching becomes difficult to achieve, and return power and current stress increase sharply, leading to very high switching losses and reduced DAB converter efficiency. Therefore, many scholars have conducted extensive research on this problem in recent years, proposing extended phase-shift (EPS) modulation, dual-phase-shift (DPS) modulation, and even triple-phase-shift (TPS) modulation. Compared to SPS modulation, these methods effectively reduce return power and current stress, expand the soft-switching range, and improve DAB converter efficiency. A common feature is that all switches operate with a 50% duty cycle.

[0004] With the rapid development of DAB (Distributed Amplifier) ​​converters, the performance requirements for DAB converters are constantly increasing to achieve wider output voltage ranges, stronger load capacity, and better anti-interference capabilities. This necessitates control strategies with better speed, robustness, and adaptability. Many control strategies have been researched for DAB converter control, including adaptive control, fuzzy control, neural network control, and active disturbance rejection control. However, adaptive algorithms require a sufficiently accurate model of the controlled object, making controller parameter determination complex; fuzzy control can introduce jitter and vibration problems into the circuit, affecting stable output; and the complex structure of neural network control makes controller design cumbersome. Therefore, all higher-level control strategies have some drawbacks in practical applications. Furthermore, traditional active disturbance rejection controllers use a nonlinear function with numerous parameters, complex adjustment, and low transmission efficiency. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a duty cycle modulation method and system based on linear ADRC voltage control, which can effectively reduce steady-state error.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an LADRC control method based on a DAB converter, comprising:

[0008] The control quantity is the unit value of the transmission power, and LADRC control is performed through the linear large-signal model of the DAB converter.

[0009] The DAB converter's linear large-signal model is based on a one-sided asymmetric duty cycle modulation method, which controls the output voltage by directly controlling the scalarized transmission power.

[0010] Furthermore, the DAB converter controls energy transmission by switching a control switch on and off, and the switching process of the control switch is a nonlinear process.

[0011] Furthermore, the DAB converter includes two H-bridges, namely the primary H-bridge and the secondary H-bridge.

[0012] Furthermore, the primary H-bridge is asymmetric in duty cycle modulation, while the secondary H-bridge is symmetric in duty cycle modulation.

[0013] Furthermore, power transmission between the two H-bridges is achieved through phase shift angle, and the single-sided asymmetric duty cycle modulation method includes two control degrees of freedom.

[0014] Furthermore, it also includes per-unit processing of the transmission power to represent the relationship between the output voltage and the transmission power.

[0015] Furthermore, it also includes taking into account the transmission losses present in the circuit to make the linear large-signal model of the DAB converter more accurate, thereby accelerating the dynamic response speed.

[0016] Furthermore, by combining the output power with the transmission power, the per-unit value p of the DAB converter's transmission power is:

[0017] p = 8(-2D) 2 -D1 2 +D+D1-0.25);

[0018] Where D1 represents the inward shift ratio; D represents the outward shift ratio.

[0019] Furthermore, it also includes estimating the total system disturbance by providing an estimated extended state observer (ESO).

[0020] Furthermore, the extended state observer (ESO) is:

[0021]

[0022] Where z1 is the state of the tracking output voltage in LESO, and z2 is the state of the tracking system total disturbance in LESO

[11] .

[0023] Secondly, a LADRC control system based on a DAB converter is provided, including: a tracking controller for tracking the total system disturbance and the state of the output voltage;

[0024] Extended state observer is used to estimate the total system disturbance;

[0025] A state error feedback controller is used to implement feedback control in response to external disturbances.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The control method proposed in this invention improves upon the traditional linear active interference suppression controller and optimizes the parameter setting process while ensuring system performance. Finally, the results were verified through a simulation platform, demonstrating a significant improvement in overall efficiency across the entire power range. The proposed control exhibits better robustness than traditional PI control and greatly simplifies the problems of excessive parameters and difficult parameter selection in traditional ADRC controller design.

[0028] Additional advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is the topology of the DAB converter provided in Embodiment 1;

[0031] Figure 2 This is a waveform diagram of the DAB converter modulation strategy provided in Embodiment 1.

[0032] Figure 3 This is the equivalent structure diagram of the DAB converter provided in Embodiment 1;

[0033] Figure 4 This is a mathematical model diagram of the DAB converter provided in Embodiment 1.

[0034] Figure 5 This is a structural diagram of the LADRC controller provided in Embodiment 1. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, 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 invention pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] In this invention, terms such as "fixed connection," "connected," and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on this invention.

[0039] Example 1

[0040] In a first aspect, the present invention provides an LADRC control method based on a DAB converter, comprising:

[0041] The control quantity is the unit value of the transmission power, and LADRC control is performed through the linear large-signal model of the DAB converter.

[0042] The DAB converter's linear large-signal model is based on a one-sided asymmetric duty cycle modulation method, which controls the output voltage by directly controlling the scalarized transmission power.

[0043] Furthermore, the DAB converter controls energy transmission by switching a control switch on and off, and the switching process of the control switch is a nonlinear process.

[0044] Furthermore, the DAB converter includes two H-bridges, namely the primary H-bridge and the secondary H-bridge.

[0045] Furthermore, the primary H-bridge is asymmetric in duty cycle modulation, while the secondary H-bridge is symmetric in duty cycle modulation.

[0046] Furthermore, power transmission between the two H-bridges is achieved through phase shift angle, and the single-sided asymmetric duty cycle modulation method includes two control degrees of freedom.

[0047] Specifically,

[0048] Figure 1The equivalent circuit diagram of the DAB converter is given, where i is the output current, i o For the output current, i C This refers to the capacitor current. The output current i2 of the converter circuit before C2 is considered a current source controlled by the transmitted power. The output voltage change is due to the charging and discharging of the output capacitor, hence the introduction of i... C This invention improves dynamic performance. It constructs a linearized and direct large-signal model based on a closed-loop controller, achieving rapid and accurate control of the output voltage by directly controlling the scalarized transmission power.

[0049] To conveniently represent the relationship between output voltage V2 and p, this paper only standardizes the transmitted power. From Figure 3 In the equivalent circuit shown, an equivalent linear large-signal mathematical model of the standardized transmission power can be obtained, such as... Figure 4 As shown. Therefore, the DC-side output current i2 and output voltage V2 of the secondary H-bridge are:

[0050]

[0051]

[0052] From the output power expression P0=V2i2, we get:

[0053] P0 = V2(i C +i0) (3)

[0054] Considering transmission losses in the circuit can make the model more accurate, thereby speeding up the dynamic response. At this point, the relationship between transmission power and output power is:

[0055]

[0056] Where η is the transmission efficiency, which is related to the control method and the circuit itself. Equation (4) can be further standardized to:

[0057]

[0058] Among them, V 2ref Using the reference voltage, the output power and transmission power are combined through equation (5). The per-unit value p of the transmission power of the DAB converter with asymmetric duty cycle modulation strategy can be expressed as:

[0059] p = 8(-2D) 2 -D1 2 +D+D1-0.25) 6)

[0060] Where D1 represents the inward shift ratio; D represents the outward shift ratio.

[0061] When the circuit state changes, the transmission power changes immediately to accelerate the dynamic response speed.

[0062] Since the transfer function of DAB is (1), the control voltage V2 can be obtained as:

[0063]

[0064] To establish an effective mathematical model of the system and consider the system disturbance f, the dynamic system of the DAB converter can be reformulated within the LADRC framework as follows:

[0065]

[0066] Where, x1 = V c For the control voltage, u is the control input variable, b0 represents the known part, Δb is the unknown modeling error, and f represents the total system disturbance.

[0067] In Active Disturbance Rejection Control (ADRC) architecture, the core idea is to find an ESO that provides an estimate f, such that the effects of f(t) can be compensated for by disturbance rejection. For system evaluation, let x1 = V C x² = f, x = [x₁, x₂] T ,y c = x1. Obviously, the state-space equation is in the form of:

[0068]

[0069] The enhanced system can be directly represented by (7), and the system state-space equation can be expressed as:

[0070]

[0071] in,

[0072] According to formula (9):

[0073]

[0074] In the formula, L and z(t) are the observer gain vector and the observer state vector, respectively, and V C Given the measured values ​​of the observer, equation (10) can be expressed as:

[0075]

[0076] Among them, u c =[u Vc]T is the input, y cThe output is the observer gain vector L, designed using the [A-LC] method, which is the Hurwitz criterion with desired eigenvalues. Applying bandwidth parameterization to the observer gain yields:

[0077] s 2 +l1s+l2=(s+w0) 2 (13)

[0078] Where ω0>0, ω0 represents the bandwidth of the second-order LESO, l1=2ω0, l2=ω0 2 , ω0 2 The ESO of this system is as follows:

[0079]

[0080] Where z1 is the state of the tracking output voltage in LESO, z2 is the state of the tracking system total disturbance in LESO, and the values ​​of l1 and l2 affect the convergence speed of LESO.

[0081] Example 2

[0082] A LADRC control system based on a DAB converter includes: a tracking controller for tracking the total system disturbance and the state of the output voltage;

[0083] Extended state observer is used to estimate the total system disturbance;

[0084] A state error feedback controller is used to implement feedback control in response to external disturbances.

[0085] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A DAB converter-based LADRC control method, characterized by, The application relates to a DAB converter-based LADRC control method, comprising the following steps: Taking a unit value of transmission power as a control quantity, LADRC control is performed through a DAB converter linear large signal model; The DAB converter linear large signal model is based on a single-side asymmetric duty cycle modulation method, and transmission power is directly controlled to realize control on output voltage; The DAB converter comprises two H bridges, namely a primary H bridge and a secondary H bridge; the primary H bridge is asymmetrically duty cycle modulated, and the secondary H bridge is symmetrically duty cycle modulated; Transmission loss existing in a circuit is considered to make the DAB converter linear large signal model more accurate, thereby accelerating a dynamic response speed; The unit value p of the transmission power of the DAB converter is combined by output power and transmission power, and is: ； Wherein, D1 is an inner phase shift ratio; and D is an outer phase shift ratio.

2. The LADRC control method based on a DAB converter according to claim 1, characterized in that, The DAB converter controls energy transmission by controlling on-off of a switch, and the on-off process of the switch is a nonlinear process.

3. The LADRC control method based on a DAB converter according to claim 1, wherein, Power transmission is realized between the two H bridges through phase shift angles, and the single-side asymmetric duty cycle modulation method comprises two control degrees of freedom.

4. The LADRC control method based on a DAB converter according to claim 3, characterized by, The transmission power is normalized to represent the relationship between the output voltage and the transmission power.

5. The LADRC control method based on a DAB converter according to claim 1, wherein, An estimated extended state observer ESO is provided to estimate total disturbance of the system.

6. A DAB-converter-based LADRC control system, characterized by, The application further discloses a DAB converter-based LADRC control method, comprising the following steps: A tracking controller is used to track states of total disturbance of the system and the output voltage; An extended state observer is used to estimate total disturbance of the system; A state error feedback controller is used to implement feedback control on external disturbance.

Images