An adaptive anti-interference control method for DC / DC components of hydrogen fuel cells

Abstract

The present invention relates to an adaptive anti-interference control method for a hydrogen fuel cell DC / DC element, which belongs to the field of DC / DC control of a hydrogen fuel cell system, and includes: first, considering parameter perturbation and harmonic interference to establish a Boost type DC / DC dynamic model; second, defining the tracking error of the system, designing a specified performance function and performing error conversion to obtain a first unconstrained error model; third, designing a virtual control variable, and designing an interference observer to obtain an estimated value of the harmonic interference; finally, defining a second error model, designing a DC / DC duty cycle adaptive control instruction, and completing the adaptive anti-interference control of the DC / DC element. The present invention realizes the inductor current control of the DC / DC element under the condition of parameter perturbation and double frequency harmonic interference, and has the characteristics of high robustness and easy engineering implementation.

Description

Technical Field

[0001] The present invention belongs to the field of converting DC power input into DC power output, and specifically relates to an adaptive anti-interference control method for DC / DC elements of a hydrogen fuel cell, which solves the control problem of DC / DC power elements with uncertain parameters and external interference. Background Art

[0002] In recent years, hydrogen fuel cells have been widely used in aerospace, automotive and other fields due to their high fuel conversion rate, low noise and zero emission. DC / DC power components are an important part of hydrogen fuel cell systems. DC / DC components convert uncontrollable direct current into controllable direct current, which is related to the normal operation of the fuel system and energy management system in hydrogen fuel cell systems. The output voltage value of DC / DC components and the current value of inductors are key factors in maintaining the normal operation of DC / DC. In actual applications, the inductance value of the inductor, the capacitance value of the capacitor, the input voltage value of the system and the resistance value of the load in the DC / DC component model may cause parameter perturbations due to inaccurate measurements or environmental influences, introduce interference, and cause inaccurate calculation of the system duty cycle and reduced control accuracy. In real life, AC components are more common. DC / DC components are often connected to DC / AC components to connect AC components. AC components will introduce double frequency harmonics to the entire DC / DC, DC / AC, and AC component systems, causing system instability. Therefore, it is necessary to estimate the double frequency interference and compensate for it to improve the stability of the system.

[0003] At present, a relatively systematic study has been carried out to solve the DC / DC anti-interference problem. The paper "Finite-Time Adaptive Neural Network Observer-Based Output Voltage-Tracking Control for DC–DC" in "IEEE Transactions on Circuits and Systems I: Regular Papers" Boost Converters proposes to estimate the interference caused by parameter perturbation through an adaptive finite-time neural network observer, and to compensate for this interference by controlling the duty cycle. However, this method has the problem of excessive calculation and requires a large amount of data as a basis. Chinese patent application CN117175913A proposes a device for pre-processing the output voltage through a set of DC / DC converter ripple collection. The system collects data through ADC, and DAC and reference voltage form an adaptive closed-loop regulation circuit to process different output voltages to achieve the purpose of adaptive attenuation of DC voltage values. Chinese utility model patent CN217769868U proposes to improve the anti-interference and stability of DC / DC through an external circuit. This external circuit is connected to the MOS tube through components such as a reference voltage source, a feedback circuit, an error amplifier, and a control circuit. By adding a dedicated control circuit that restricts the feedback closed loop, damage to the subsequent chip when the DC / DC is interfered is prevented. The above two methods both use additional circuits to deal with the interference problem of DC / DC, which increases the volume and cost of the DC / DC system. In summary, there is an urgent need for an adaptive control method that can simultaneously handle parameter perturbations and double frequency interference without increasing system size and cost and without relying on large amounts of data. Summary of the invention

[0004] Aiming at the control problem of composite interference caused by DC / DC's own parameter perturbation and the introduction of double frequency harmonics after the introduction of DC / AC in a hydrogen fuel system, and in order to overcome the deficiencies of the prior art, the present invention provides an adaptive anti-interference control method for DC / DC elements of a hydrogen fuel cell, which realizes rapid estimation and compensation of composite interference, and realizes stabilization of the DC / DC inductor current by designing a specified performance function and performing error changes in the case of parameter perturbation and double frequency interference, using adaptive technology to process parameter perturbations, using an observer to process double frequency harmonics.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for adaptive anti-interference control of a DC / DC element of a hydrogen fuel cell comprises the following steps:

[0007] The first step is to consider the parameter perturbations of the power components in the hydrogen fuel system and the harmonic interference introduced by the AC components in the actual application scenario, and establish a boost type DC / DC dynamic model;

[0008] In the second step, based on the Boost DC / DC dynamic model in the first step, the tracking error of the system is defined, the specified performance function is designed and the error is converted to obtain the first unconstrained error model;

[0009] The third step is to design virtual control variables and disturbance observers based on the first unconstrained error model in the second step to obtain the estimated value of harmonic disturbance;

[0010] The fourth step is to define the second error model based on the disturbance observer in the third step, design the DC / DC duty cycle adaptive control instruction, and complete the DC / DC component adaptive anti-interference control.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: the existing control methods cannot take into account both parameter perturbation and double frequency interference while controlling volume and cost. The present invention uses an adaptive method to deal with the parameter perturbation problem of DC / DC components; at the same time, an interference observer is designed to estimate the possible double frequency interference of DC / DC, and quickly estimate and compensate for it, and the interference occurring in the system is handled by the duty cycle, which does not increase the volume of the system and can quickly compensate for the interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The present invention is a flow chart of a method for adaptively controlling a DC / DC element of a hydrogen fuel cell. DETAILED DESCRIPTION

[0013] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0014] like Figure 1 As shown, the present invention discloses a hydrogen fuel cell DC / DC element adaptive anti-interference control method, comprising the following steps:

[0015] The first step is to consider the parameter perturbations of the power components in the hydrogen fuel system and the harmonic interference introduced by the AC components in the actual application scenario, and establish a boost type DC / DC dynamic model;

[0016] In the second step, based on the Boost DC / DC dynamic model in the first step, the tracking error of the system is defined, the specified performance function is designed and the error is converted to obtain the first unconstrained error model;

[0017] The third step is to design virtual control variables based on the first unconstrained error model in the second step, and to design a disturbance observer to obtain the estimated value of the harmonic disturbance;

[0018] The fourth step is to define the second error model based on the disturbance observer in the third step, design the DC / DC duty cycle adaptive control instructions, and complete the DC / DC component adaptive control.

[0019] The present invention solves the parameter perturbation problem in the experimental process and the double frequency harmonic problem in practical applications, can accurately estimate the interference value and perform rapid compensation, and enhances the stability of DC / DC.

[0020] Specifically, the first step includes:

[0021] Considering the inductance value of the inductor, capacitance value of the capacitor, input voltage value and load resistance value of the power element in the hydrogen fuel system, the parameter perturbation caused by inaccurate measurement or environmental influence, and the harmonic interference introduced by the AC element in the actual application scenario, according to the DC / DC element physics model and Kirchhoff's law of current and voltage, a second-order nonlinear dynamic model of the DC / DC element in the hydrogen fuel cell system is established:

[0022]

[0023] Where x1 = i L is the inductor current value in the DC / DC system; x2 = v o Output voltage value of DC / DC system; Respectively represent the derivatives of x1 and x2; u is the duty cycle of the DC / DC system; L is the inductance of the inductor in the DC / DC system; C is the capacitance of the capacitor in the DC / DC system; R is the resistance of the external resistor of the DC / DC system; V in represents the voltage value output by the hydrogen fuel cell connected to the DC / DC system; d is harmonic interference; considering the parameter perturbation caused by the change of environmental factors or the slow drift of parameters during the operation of the system, L, C, R and V in All are unknown parameters;

[0024] Considering that the DC / DC system connected to DC / AC and AC components will introduce harmonic signals, the harmonic signals are expressed as:

[0025]

[0026] Among them, U ac ,I ac are the AC voltage and current values ​​connected to the DC / DC system respectively; ω is the AC frequency connected to the DC / DC system, which is 50Hz; θ is the phase angle deflection between the system voltage and current caused by the AC signal.

[0027] Specifically, in the second step, the first unconstrained error model is:

[0028]

[0029] Among them, y(t)=x1 is the system output; y d (t) is the expected value of the system, abbreviated as y d ;e y (t) is the difference between the system output and the system expected value, abbreviated as e y ; p(t) is the specified performance function, abbreviated as p; z1 is the first error-free model; F is about e y function of (t) and p(t); p0>p ∞ >0,m>0, ρ >0 and All are preset constants; and- ρ p0 represents the upper and lower bounds of the error, The steady-state value of error convergence is limited, the exponent m determines the rate of error convergence; t represents the running time.

[0030] Specifically, the third step includes:

[0031]

[0032] Among them, Y, α, ξ and μ are auxiliary variables; c1>0, γ>0, W, N and S are design parameters. Choose a suitable N so that W-NS is a Hurwitz matrix; and are p, μ and y respectively d The derivative of and are the derivative and estimate of ξ respectively; is the estimated value of Θ; The role is to take The first value of w * is the virtual control quantity; and They are the estimated values ​​of inductance L and harmonic interference d, for The derivative of .

[0033] Specifically, the fourth step includes:

[0034]

[0035] Among them, z2 is the second error model; w *is the virtual control quantity; β, A, Q are auxiliary variables; Γ and c2 are design parameters, c2>0, Γ is a positive definite matrix; is the estimated value of the intermediate parameter Θ The derivative of and They are y d and the second derivative of p; auxiliary variables is the derivative of the duty cycle of the DC / DC system.

[0036] The DC / DC inductor current control of the present invention can estimate the interference value and quickly compensate for the harmonic interference caused by the system parameters being perturbed and the external DC / AC and AC components, thereby ensuring that the tracking error of the system converges to 0, which is beneficial to improving the stability of the system.

[0037] Although the above describes the illustrative specific embodiments of the present invention to facilitate the understanding of the present invention by those skilled in the art, and it should be clear that the present invention is not limited to the scope of the specific embodiments, for those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

Claims

1. A hydrogen fuel cell DC / DC element adaptive anti-interference control method, characterized in that: The following steps are involved: The first step is to consider the parameter perturbations of the power components in the hydrogen fuel system and the harmonic interference introduced by the AC components in the actual application scenario, and establish a boost type DC / DC dynamic model; In the second step, based on the Boost DC / DC dynamic model in the first step, the tracking error of the system is defined, the specified performance function is designed and the error is converted to obtain the first unconstrained error model; The third step is to design virtual control variables based on the first unconstrained error model in the second step, and to design a disturbance observer to obtain an estimate of the harmonic disturbance, including: in, and All are auxiliary variables; is the inductor current value in the DC / DC system; Output voltage value of DC / DC system; , and is the design parameter, , , select , so that is the Hurwitz matrix; and They are derivatives and estimates of ; Harmonic interference The estimated value of is an auxiliary variable The derivative of The AC frequency for access to the DC / DC system is 50Hz; is the duty cycle of the DC / DC system; is the capacitance value of the capacitor in the DC / DC system; The resistance value of the external resistor of the DC / DC system; The fourth step is to define the second error model based on the disturbance observer in the third step, design the DC / DC duty cycle adaptive control instruction, and complete the DC / DC component adaptive anti-interference control.

2. A hydrogen fuel cell DC / DC element adaptive anti-interference control method according to claim 1, characterized in that: The first step comprises: According to the physical model of Boost type DC / DC components and Kirchhoff's law of current and voltage, a second-order nonlinear dynamic model of DC / DC components in hydrogen fuel cell systems is established, namely, the Boost type DC / DC dynamic model: in, is the inductor current value in the DC / DC system; Output voltage value of DC / DC system; , Respectively , The derivative of is the duty cycle of the DC / DC system; is the inductance value of the inductor in the DC / DC system; is the capacitance value of the capacitor in the DC / DC system; The resistance value of the external resistor of the DC / DC system; Indicates the voltage value output by the power supply hydrogen fuel cell connected in front of the DC / DC system; It is harmonic interference; , , and All are unknown parameters; The DC / DC system is followed by DC / AC and AC components, which introduce harmonic interference , expressed as: in, , They are the AC voltage value and AC current value connected to the DC / DC system respectively; The AC frequency for access to the DC / DC system is 50Hz; The phase angle deviation between system voltage and current caused by the AC signal.

3. A hydrogen fuel cell DC / DC element adaptive anti-interference control method according to claim 2, characterized in that: In the second step, the first unconstrained error model is: in, Output for the system; is the expected value of the system, referred to as ; It is the difference between the system output and the system expected value, referred to as ; is a specified performance function, referred to as ; t represents time; is the first error-free model; About and Function of , , and All are preset constants; and- represent the upper and lower bounds of the error respectively, Limits the error to converge to a steady-state value, exponential Determines the rate at which the error converges.

4. The method for adaptive anti-interference control of a hydrogen fuel cell DC / DC element according to claim 3, characterized in that: The fourth step comprises: in, is the second error model, defined as ; is an auxiliary variable, and its expression is: ; and is the design parameter, , is a positive definite matrix; is the intermediate parameter Estimated value of The derivative of and are the expected values ​​of the system and specify performance functions The second derivative of; auxiliary variables ; is the derivative of the DC / DC duty cycle; is the virtual control quantity, and its expression is expressed as ; and They are the inductance value L and harmonic interference of the inductor in the DC / DC system respectively. The estimated value of for The derivative of is calculated as , intermediate parameters , for An estimated value of , the role is to take The first value of , and They are specified performance functions , auxiliary variables and the expected value of the system The derivative of ; the superscript T indicates the transpose of the matrix; , is the design parameter; , is an auxiliary variable.

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