An Active Filtering and Disturbance Rejection Control Method for a DC-DC Converter System

Abstract

The present invention discloses an active filtering and disturbance rejection control method for a DC-DC converter system. A dynamic model of the DC-DC converter system affected by measurement noise and parameter perturbation is established. On the basis of this model, an extended state observer based on a Kalman filter is constructed to obtain the estimated information of the filtered lumped disturbance, the estimated information of the output voltage and the inductor current. Then, the dynamic equation of the voltage tracking error is obtained by combining the output voltage command information, and an output feedback controller is designed based on the estimated information. The proposed method ensures the smoothness of the state estimation information and the lumped disturbance estimation information, thereby ensuring the smoothness and continuity of the control quantity. At the same time, based on the design method of the extended state observer of the Kalman filter, the effective suppression of measurement noise is ensured, the limitation of the observer bandwidth is relaxed, and thus the observation effect and control accuracy are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic conversion, and in particular to an active filtering and disturbance rejection control method for a DC-DC converter system. Background Art

[0002] DC-DC converter systems are widely used as power conversion scenarios in industrial systems due to their high energy conversion efficiency. The diversification of application scenarios has complicated the working environment of DC-DC converter systems, which inevitably brings multi-source interferences such as system structure parameter perturbation and input voltage perturbation, posing a great challenge to the high-precision voltage command tracking of the converter system. In addition, limited by measuring instruments, the output voltage measurement signal for feedback regulation will inevitably be affected by measurement noise, which further affects the output voltage tracking accuracy of the DC-DC converter system.

[0003] Regarding the problem of poor output voltage tracking accuracy of DC-DC converter systems caused by parameter perturbation, scholars at home and abroad have proposed various solutions. Among them, the active disturbance rejection control method based on disturbance observation compensation has been widely recognized and studied because it realizes the feedforward fast compensation of disturbances to ensure high-precision tracking of the output voltage. However, this active disturbance rejection control method cannot handle the influence of measurement noise on control accuracy, and as the measurement noise increases, it will significantly limit the bandwidth of the disturbance observer, thereby affecting the disturbance suppression effect. Therefore, there is an urgent need to propose an active filtering-disturbance rejection control method for DC-DC converter systems that can handle multi-source interferences and measurement noise simultaneously. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide an active filtering and disturbance rejection control method for a DC-DC converter system, which can achieve high-precision estimation of states and lumped disturbances and effective suppression of measurement noise in the presence of both measurement noise and multi-source interferences, and use the filtered estimation information for the design of the controller to realize disturbance compensation under continuous control quantities, so as to ensure the effective suppression of measurement noise and multi-source interferences of the DC-DC converter system, and thus achieve high-precision tracking of the output voltage.

[0005] Technical Solution: An active filtering and disturbance rejection control method for a DC-DC converter system provided by the present invention includes the following steps:

[0006] S1. Establish a dynamic model of the DC-DC converter system. Considering the parameter perturbation of the supply voltage and the inductor, establish a dynamic model of the DC-DC converter system under perturbed states;

[0007] S2. Based on the dynamic model of the DC-DC converter system under the perturbed state, design an extended state observer based on the Kalman filter to obtain the estimated information of the state and the lumped disturbance;

[0008] S3. Combine the state and the estimated information of the lumped disturbance to design an active filtering disturbance rejection output feedback controller.

[0009] Further, in step S1, the dynamic model of the DC-DC converter system is:

[0010]

[0011]

[0012] where L is the inductor, C is the capacitor, and R is the resistor; V i is the voltage value of the DC voltage on the power supply side; μ is the input of the control system, V o is the output of the control system, the physical meaning of μ is the duty cycle, and V o the physical meaning is the output voltage; I L is the current flowing through the inductor;

[0013] Considering the perturbation of the DC voltage V i on the power supply side and the parameter perturbation of the inductor L, the dynamic model of the DC-DC converter system under the perturbed state is:

[0014]

[0015]

[0016] where V i n is the nominal value of the power supply voltage V i L n is the nominal value of the inductor L, is the first derivative of the output V o of the control system, is the first derivative of the current I L flowing through the inductor. Considering the influence of the sensor measurement noise, the above perturbed dynamic model becomes:

[0017]

[0018]

[0019] where, is the measured value of the output voltage, w is the measurement noise caused by sensors, etc. during the measurement process; d is the lumped disturbance caused by the perturbation of the DC voltage V i on the power supply side and the inductor L, and its specific expression is:

[0020]

[0021] Furthermore, in step S2, the following steps are included:

[0022] 2.1) Based on the dynamic model of the DC-DC converter system under the perturbed state, design the following Kalman filter:

[0023]

[0024] where x1 and x2 are both intermediate states of the Kalman filter, is the derivative of x1, is the derivative of x2, is the lumped disturbance estimate value, obtained by the extended state observer in step 2.2), and K s is the filter coefficient, dynamically obtained through the following equation:

[0025]

[0026]

[0027] where P ∈ R 2×2 is a time-varying matrix function, R is the measurement noise covariance, and R -1 is the inverse matrix of R, Q d is the estimation error covariance, and A, B d , C m are constant matrices, A T is the transpose of A, B d T is the transpose of B d and C m T is the transpose of C m The values of A, B d , C m are determined by the Kalman filter formula, and the specific values are:

[0028]

[0029] 2.2) Based on the output of the Kalman filter, design an extended state observer to obtain the state and lumped disturbance estimation information. The extended state observer is designed as follows:

[0030]

[0031]

[0032]

[0033]

[0034] Among them, z1, z2, and z3 are all intermediate states of the extended state observer. is the estimated value of the output voltage. is the estimated value of the inductor current. is the estimated value of the lumped disturbance. x1 is the information of the output voltage after being filtered by the Kalman filter, obtained by the Kalman filter in step 2.1); L O1 , L O2 , L O3 are all observer gains, and all solutions of the following characteristic equation about s have negative real parts:

[0035]

[0036] Furthermore, in step S3, the following steps are included:

[0037] 3.1) According to the formula

[0038]

[0039]

[0040] Combined with the output voltage command V r , obtain the dynamic equation of the output voltage tracking error:

[0041]

[0042]

[0043] Among them is the first derivative of the output voltage command V r , is the second derivative of the output voltage command V r , e = V o - V r is the tracking error of the output voltage, is the first derivative of the output voltage tracking error, is the second derivative of the output voltage tracking error;

[0044] 3.2) Combine the state and the estimated information of the lumped disturbance obtained by the extended state observer based on the Kalman filter to construct an active filtering and disturbance rejection output feedback controller for the DC-DC converter system:

[0045]

[0046] Among them, k1 and k2 are both controller parameters, and their values are all positive numbers. are all obtained by the extended state observer in step 2.2). is the estimated value of the output tracking error, is the estimated value of the derivative of the output tracking error, and its specific implementation is as follows:

[0047]

[0048] Beneficial effects: Compared with the prior art, the remarkable feature of the present invention is that a Kalman filter is introduced in the design process of the extended state observer, which ensures the smoothness of the state estimation information and the lumped disturbance estimation information, and further ensures the smoothness and continuity of the control quantity, realizes the effective suppression of measurement noise, relaxes the limitation of the observer bandwidth, and further improves the observation effect and control accuracy. Description of the Drawings

[0049] Figure 1 is the structural block diagram of the present invention;

[0050] Figure 2 is the comparison diagram of the output voltage tracking error;

[0051] Figure 3 is the comparison diagram of the inductor current response;

[0052] Figure 4 is the comparison diagram of the duty ratio response of the inductor current control quantity;

[0053] Figure 5 is the comparison diagram of the output voltage estimation effect;

[0054] Figure 6 is the comparison diagram of the inductor current estimation effect;

[0055] Figure 7 is the comparison diagram of the lumped disturbance estimation effect. Detailed Embodiment

[0056] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0057] Embodiment 1

[0058] Please refer to Figure 1 As shown, a method for active filtering and disturbance rejection control of a DC-DC converter system provided by the present invention includes the following steps:

[0059] S1. Establish the dynamic model of the DC-DC converter system. Considering the parameter perturbation of the power supply voltage and the inductor, establish the dynamic model of the DC-DC converter system under the disturbed state. Among them, the dynamic model of the DC-DC converter system is:

[0060]

[0061] Among them, L is the inductor, C is the capacitor, and R is the resistor; V iis the voltage value of the DC voltage on the power supply side; μ is the input of the control system, V o is the output of the control system. The physical meaning of μ is the duty cycle, V o The physical meaning is the output voltage; I L is the current flowing through the inductor.

[0062] Considering the perturbation of the DC voltage V i on the power supply side and the parameter perturbation of the inductor L, the dynamics of formula (1) under the perturbed state is written as:

[0063]

[0064] where, V i n is the nominal value of the supply voltage V i and L n is the nominal value of the inductor L. is the first derivative of the output V o of the control system, is the first derivative of the current I L flowing through the inductor. In this embodiment, C = 2×10 -4 F, R = 1×10 3 Ω, V i n = 100V, L n = 0.5H.

[0065] Considering the influence of sensor measurement noise, the dynamics of formula (2) under the perturbed state is written as:

[0066]

[0067] where, is the measured value of the output voltage, w is the measurement noise brought by sensors and others during the measurement process; d is the lumped disturbance caused by the perturbation of the DC voltage V i on the power supply side and the parameter perturbation of the inductor L. Its specific expression is:

[0068]

[0069] In this embodiment, the measurement noise w is random white noise, and its value satisfies w ~ N(0,1); the values of the input voltage and inductor parameters after perturbation are:

[0070]

[0071] S2. Based on the dynamic model of the DC-DC converter system under the perturbed state, design an extended state observer based on the Kalman filter to obtain the estimated information of the state and the lumped disturbance.

[0072] 2.1) Based on the dynamic model (3), the following Kalman filter is designed by combining the measured value of the output voltage:

[0073]

[0074] where both \(x_1\) and \(x_2\) are intermediate states of the Kalman filter, is the derivative of \(x_1\), is the derivative of \(x_2\), is the lumped disturbance estimate value, obtained by the extended state observer, and \(K\) s is the filter coefficient, dynamically obtained through the following equation:

[0075]

[0076] where \(P\in R\) 2×2 is a time-varying matrix function, \(R\) is the measurement noise covariance, and \(R\) -1 is the inverse matrix of \(R\), \(Q\) d is the estimation error covariance, and \(A\), \(B\) d , \(C\) m are constant matrices, \(A\) T is the transpose of \(A\), \(B\) d T is the transpose of \(B\), and \(C\) d is the transpose of \(C\); the values of \(A\), \(B\) m T and \(C\) m are determined by equation (5), and the specific values are: d , \(C\) m In this embodiment, the measurement noise covariance is \(R = 1\), and the estimation error covariance is set to \(Q\)

[0077]

[0078] d = 2.

[0079]

[0079] 2.2) Based on the output of the Kalman filter, an extended state observer is designed to obtain the state and lumped disturbance estimation information. The extended state observer is designed as follows:

[0080]

[0081] where \(z_1\), \(z_2\), and \(z_3\) are all intermediate states of the extended state observer, is the estimated value of the output voltage, is the estimated value of the inductor current, is the estimated value of the lumped disturbance, and \(x_1\) is the information of the output voltage after being filtered by the Kalman filter, obtained by the Kalman filter; \(L\) O1 , \(L\) O2 , \(L\) O3They are all observer gains, and all solutions that satisfy the following characteristic equation with respect to s have negative real parts:

[0082]

[0083] In this embodiment, the specific values of the observer gains are:

[0084]

[0085] where p o is the configured pole of the observer, and its value is p o = 100.

[0086] S3. Combine the state and the estimated information of the lumped disturbance to design an active filtering disturbance rejection output feedback controller.

[0087] 3.1) According to formula (3), combine the output voltage command V r , and obtain the dynamic equation of the output voltage tracking error:

[0088]

[0089] where are the first-order derivatives of the output voltage command V r respectively, is the second-order derivative of the output voltage command V r . In this embodiment, V r = 50, e = V o - V r is the tracking error of the output voltage, is the first-order derivative of the output voltage tracking error, is the second-order derivative of the output voltage tracking error.

[0090] 3.2) Combine the state of the extended state observer based on the Kalman filter and the estimated information of the lumped disturbance to construct an active filtering disturbance rejection output feedback controller for the DC-DC converter system:

[0091]

[0092] where k1 and k2 are both controller parameters, and their values are all positive numbers, are all obtained from the extended state observer (8) based on the Kalman filter, is the estimated value of the output tracking error, is the estimated value of the derivative of the output tracking error, and its specific values are:

[0093]

[0094] In this embodiment, the specific values of the controller parameters in formula (11) are k1 = 400 and k2 = 40.

[0095] To verify the anti-interference performance, high-precision tracking characteristics, and measurement noise suppression performance of the method proposed in the present invention, the control algorithm proposed in the present invention is simulated and verified based on the MATLAB simulation environment considering parameter perturbation and output measurement noise.

[0096] During the simulation, the initial values of the output voltage and inductor current are set to V o (0) = 0, I L (0) = 0, and the initial values of the intermediate states of the Kalman filter and the extended state observer are all set to 0, that is

[0097] x1(0) = 0, x2(0) = 0; z1(0) = 0, z2(0) = 0, z3(0) = 0.

[0098] The initial value of the system state for solving the dynamic equation (5) of the Kalman filter gain is set to:

[0099]

[0100] The form of the proposed active filtering disturbance rejection output feedback controller and the controller parameters have been given in the design example. To demonstrate the superiority of the proposed method, the traditional active disturbance rejection controller based on the extended state observer is also used in the DC-DC converter simulation system. The observer and the controller of this method are designed as follows:

[0101]

[0102]

[0103]

[0104]

[0105]

[0106] Among them

[0107]

[0108] The observer gain and the controller gain of this traditional active disturbance rejection control method are designed as follows:

[0109]

[0110] k1 = 400, k2 = 40

[0111] The active filtering and disturbance rejection control method for a DC-DC converter system provided by the present invention achieves high-precision tracking of the output voltage command under the simultaneous action of system input voltage, inductor parameter perturbation, and measurement noise.

[0112] The output voltage tracking error response curves of the DC-DC converter system under the action of the active filtering and anti-interference controller provided by the present invention and the active anti-interference controller for comparison are as Figure 2 shown. It can be seen from Figure 2 that the proposed method has higher tracking accuracy and the output tracking error is smoother.

[0113] The duty cycle responses of the control quantity of the DC-DC converter system under the action of the active filtering and anti-interference controller provided by the present invention and the active anti-interference controller for comparison are as Figure 4 shown. It can be seen from Figure 4 that the duty cycle of the control quantity under the action of the proposed method is smoother, resulting in a smoother corresponding state of the inductor current of the system, as Figure 3 shown. The proposed method ensures the smoothness of the control quantity, avoids rapid high-frequency changes of the control quantity, and is more conducive to the execution of control commands by actuators in industrial systems.

[0114] The filtering extended state observer provided by the present invention and the extended state observer for comparison perform operations of three different methods: the operation of the output voltage estimation effect. After comparison, it is as Figure 5 shown; the operation of the inductor current estimation effect. After comparison, it is as Figure 6 shown; the operation of the lumped disturbance estimation effect. After comparison, it is as Figure 7 shown;

[0115] It can be seen that compared with the traditional extended state observer, the filtering extended state observer provided by the present invention realizes higher-precision estimation of the state and lumped disturbance of the DC-DC converter system, significantly weakens the influence of measurement noise, and ensures the smoothness of the estimated value.

Claims

1. An active filtering and disturbance rejection control method for a DC-DC converter system, characterized in that It includes the following steps: S1. Establish the dynamic model of the DC-DC converter system. Considering the parameter perturbations of the supply voltage and the inductor, establish the dynamic model of the DC-DC converter system under the perturbed state; S2. Based on the dynamic model of the DC-DC converter system under the perturbed state, design an extended state observer based on the Kalman filter to obtain the estimated information of the state and the lumped disturbance; S3. Combine the estimated information of the state and the lumped disturbance to design an active filtering disturbance rejection output feedback controller; specifically, it includes the following steps: 3.1) According to the formula Combined with the output voltage command V r , the dynamic equation of the output voltage tracking error is obtained as follows: wherein is the first derivative of the output voltage command V r , is the second derivative of the output voltage command V r , e = V o - V r is the tracking error of the output voltage is the first derivative of the output voltage tracking error is the second derivative of the output voltage tracking error; 3.2) Combine the estimated information of the state and the lumped disturbance obtained by the extended state observer based on the Kalman filter to construct the active filtering disturbance rejection output feedback controller of the DC-DC converter system: wherein, both k1 and k2 are controller parameters, and their values are all positive numbers. Both are obtained by the extended state observer in step 2.2). is the estimated value of the output tracking error. is the estimated value of the derivative of the output tracking error, and its specific implementation is as follows:

2. The active filtering and disturbance rejection control method for the DC-DC converter system according to claim 1, wherein In step S1, the dynamic model of the DC-DC converter system is: Among them, L is the inductance, C is the capacitance, and R is the resistance; V i is the voltage value of the DC voltage on the power supply side; μ is the input of the control system, V o is the output of the control system, and the physical meaning of μ is the duty cycle, V o whose physical meaning is the output voltage; I L is the current flowing through the inductor; Considering the perturbation of the DC voltage V on the power supply side i and the parameter perturbation of the inductor L, the dynamic model of the DC-DC converter system under the perturbed state is as follows: Among them, V i n is the nominal value of the power supply voltage V i , L n is the nominal value of the inductor L is the first derivative of the output V o of the control system is the first derivative of the current I L flowing through the inductor. Considering the influence of the sensor measurement noise, the above perturbed dynamic model becomes: Among them, is the measured value of the output voltage, w is the measurement noise caused by sensors, etc. during the measurement process; d is the lumped interference caused by the perturbation of the DC voltage V i on the power supply side and the inductor L, and its specific expression is:

3. The active filtering and disturbance rejection control method for the DC-DC converter system according to claim 1, wherein In step S2, it includes the following steps: 2.1) Based on the dynamic model of the DC-DC converter system under the perturbed state, design the following Kalman filter: where x1 and x2 are both intermediate states of the Kalman filter, is the derivative of x1, is the derivative of x2, is the lumped disturbance estimation value obtained by the extended state observer in step 2.2), and K s is the filter coefficient, which is dynamically obtained through the following equation: where \(P\in\mathbb{R}\) 2×2 is a time-varying matrix function, \(R\) is the measurement noise covariance, and \(R\) -1 is the inverse matrix of \(R\), \(Q\) d is the estimation error covariance, and \(A\), \(B\) d , \(C\) m are constant matrices, \(A\) T is the transpose of \(A\), \(B\) d T is the transpose of \(B\), \(C\) d is the transpose of \(C\), \(A\), \(B\) m T is the transpose of \(C\), and the values of \(A\), \(B\) m , \(C\) d are determined by the Kalman filter formula, and the specific values are as follows: m ​ 2.2) Design an extended state observer based on the output of the Kalman filter to obtain the estimated information of the state and the lumped disturbance. The extended state observer is designed as follows: where z1, z2, and z3 are all intermediate states of the extended state observer, is the estimated value of the output voltage, is the estimated value of the inductor current, is the estimated value of the lumped disturbance, and x1 is the information obtained by filtering the output voltage through the Kalman filter, which is obtained by the Kalman filter in step 2.1); L O1 , L O2 , L O3 are all observer gains, and all solutions of the following characteristic equation with respect to s have negative real parts:

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