Mean value model construction method and device, computer device and storage medium

Abstract

The application relates to an average value model construction method and device, computer equipment and a storage medium. The method comprises the following steps: analyzing a single-phase-shift modulation waveform based on a preset switching function to obtain switching parameters under single-phase-shift modulation; constructing a corresponding target state equation based on the switching parameters and circuit parameters; performing Fourier decomposition on a non-sinusoidal signal according to a Fourier series decomposition equation to obtain a target sinusoidal component to be solved; solving an equation according to a k-th coefficient of the Fourier series to obtain a k-th coefficient of the Fourier series corresponding to the switching parameters and the target state variable; and constructing an arbitrary-order average value model based on the switching parameters, the target sinusoidal component to be solved, the k-th coefficient of the Fourier series and multiple parameters of the target state equation. The application can analyze the switching parameters by using a multi-order switching function, and an arbitrary-order average value model capable of more accurately representing target state variables and high-frequency characteristics of a system is obtained.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a method, apparatus, computer device, and storage medium for constructing an average value model. Background Technology

[0002] Currently, most research on solid-state transformers uses average-value models to characterize their metastable-state characteristics. The parameters of these models are obtained through port testing and formula inversion. In addition, there are discrete-time models and steady-state frequency domain models that consider multi-harmonic characteristics. Existing solid-state transformer models can be summarized into the following categories: average-value models, discrete-time models, and steady-state frequency domain models.

[0003] Unlike conventional power frequency transformers, solid-state transformers are isolated by high-frequency transformers, resulting in high-frequency square wave voltages with complex frequency components. This leads to nonlinear changes in inductor current and oscillations in the DC bus voltage, necessitating the development of multi-harmonic analysis models for solid-state transformers. Existing average value models typically only consider the DC component and the first harmonic component, neglecting higher-order components. This makes it difficult to characterize the evolution of harmonics and broadband oscillations in solid-state transformers within high-proportion renewable energy DC microgrids, potentially leading to control failures.

[0004] Discrete-time models have high accuracy but low iterative computation efficiency. Steady-state frequency domain models can characterize the multi-harmonic characteristics of solid-state transformers, but can only characterize the steady-state characteristics of the system. They are mainly used for the study of phase-shifting modulation strategies for solid-state transformers, and have poor adaptability in control loop design and stability analysis. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer equipment, and storage medium for constructing an average value model that can accurately characterize the harmonic characteristics of solid-state transformers, addressing the aforementioned technical problems.

[0006] In a first aspect, this application provides a method for constructing an average value model, used to create an arbitrary-order average value model for a dual active full-bridge converter, the method comprising:

[0007] Based on the analysis of the single-phase-shift modulation waveform driving the dual active full-bridge converter using a preset switching function, the switching parameters under single-phase-shift modulation are obtained.

[0008] Based on the switching parameters and the circuit parameters of the dual active full-bridge converter, a corresponding target state equation is constructed.

[0009] Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the target state variables within the switching cycle are decomposed using Fourier decomposition to obtain the target sinusoidal components to be solved.

[0010] Solve the equations using the k-th order coefficients of the Fourier series, and then solve for the k-th order coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables.

[0011] Based on the switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation, an arbitrary-order average value model is constructed.

[0012] In one embodiment, the step of analyzing the single-phase-shift modulation waveform driving the dual active full-bridge converter based on a preset switching function to obtain the switching parameters under single-phase-shift modulation includes:

[0013] The single-phase-shift modulation waveform is analyzed based on the primary and secondary H-bridge switching functions to obtain the switching parameters.

[0014] In one embodiment, the primary H-bridge switching function includes:

[0015]

[0016] The secondary H-bridge switching function includes:

[0017]

[0018] Where g1(t) is the primary H-bridge switching function, n is an integer, and T s d is the switching period; g5(t) is the secondary H-bridge switching function; d is the phase shift ratio of the primary H-bridge switch and the secondary H-bridge switch of the dual active full-bridge converter; and t is the time variable.

[0019] In one embodiment, constructing the corresponding target state equation based on the switching parameters and the circuit parameters of the dual active full-bridge converter includes:

[0020] The inductor current state equation is constructed based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0021] The output voltage state equation is constructed based on the switching parameters and the circuit parameters of the dual active full-bridge converter. The switching parameters include the switching parameters of the primary H-bridge switch and the switching parameters of the secondary H-bridge switch. The circuit parameters include inductor current, input voltage, output voltage, output current, output resistance, output capacitance, transformer equivalent inductance, wire switch equivalent resistance, and the transformation ratio of the primary and secondary windings of the transformer.

[0022] In one embodiment, the step of performing Fourier decomposition on the non-sinusoidal signal corresponding to the target state variable within the switching cycle according to the Fourier series decomposition equation to obtain the target sinusoidal component includes:

[0023] Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the inductor current state variables within the switching cycle are decomposed using Fourier decomposition to obtain the DC component and harmonic component of the inductor current state variables to be solved.

[0024] Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the output voltage state variables within the switching cycle are decomposed using Fourier decomposition to obtain the DC component and harmonic components of the output voltage state variables to be solved.

[0025] In one embodiment, the step of solving the equation based on the k-th order coefficients of the Fourier series to determine the switching parameters and the target state variable includes:

[0026] Solve the equations using the k-th order coefficients of the Fourier series to determine the k-th order coefficients of the Fourier series corresponding to the switching parameters, the inductor current state variable, and the output voltage state variable.

[0027] In one embodiment, constructing an arbitrary-order average value model based on the switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the polynomial parameters of the target state equation includes:

[0028] Based on the multiple parameters of the target state equation and the k-th degree coefficients of the Fourier series, the coefficients of the first state equation, the coefficients of the second state equation, and the coefficients of the third state equation are obtained.

[0029] Based on the input voltage and the output current, the input variables are obtained;

[0030] Based on the target sinusoidal component to be solved, the independent variable is obtained;

[0031] The output variable is determined based on the inductor current and the output voltage;

[0032] The arbitrary-order average value model is constructed based on the coefficients of the first state equation, the coefficients of the second state equation, the coefficients of the third state equation, the input variable, the independent variable, and the output variable.

[0033] Secondly, this application also provides an average value model construction apparatus for creating an arbitrary-order average value model for a dual active full-bridge converter, the apparatus comprising:

[0034] The waveform analysis module is used to analyze the single-phase-shift modulation waveform driving the dual active full-bridge converter based on a preset switching function, so as to obtain the switching parameters under single-phase-shift modulation.

[0035] The state equation construction module is used to construct the corresponding target state equation based on the switch switching parameters and the circuit parameters of the dual active full-bridge converter.

[0036] The Fourier decomposition module is used to perform Fourier decomposition on the non-sinusoidal signals corresponding to the target state variables within the switching cycle according to the Fourier series decomposition equation, so as to obtain the target sinusoidal components to be solved.

[0037] The coefficient calculation module is used to solve the equation based on the k-th degree coefficients of the Fourier series, and to solve for the k-th degree coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables.

[0038] The model building module is used to construct an arbitrary-order average value model based on the switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation.

[0039] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the average value model construction method described in the first aspect.

[0040] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the average value model construction method described in the first aspect.

[0041] In summary, this application proposes a method, apparatus, computer device, and storage medium for constructing an average value model. The method includes: analyzing a single-phase-shift modulation waveform based on a preset switching function to obtain switching parameters under single-phase-shift modulation; constructing a corresponding target state equation based on the switching parameters and circuit parameters; performing Fourier decomposition on the non-sinusoidal signal according to the Fourier series decomposition equation to obtain the target sinusoidal component to be solved; solving the equation based on the k-th order coefficients of the Fourier series to solve for the switching parameters and the target state variable; and constructing an arbitrary-order average value model based on the switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multiple parameters of the target state equation. This application obtains an arbitrary-order average value model that can more accurately characterize the target state variable and the high-frequency characteristics of the system by using a multi-order switching function to analyze the switching parameters. Attached Figure Description

[0042] Figure 1This is a diagram illustrating the application environment of the average value model construction method in one embodiment;

[0043] Figure 2 This is a flowchart illustrating the method for constructing an average value model in one embodiment;

[0044] Figure 3 This is a schematic diagram of the switching characteristics of the primary H-bridge switch and the secondary H-bridge switch in a dual active full-bridge converter under a single phase-shift modulation waveform in one embodiment.

[0045] Figure 4 This is a flowchart illustrating the steps involved in constructing the target state equation in one embodiment.

[0046] Figure 5 This is a schematic diagram of the steps involved in performing Fourier decomposition in one embodiment;

[0047] Figure 6 This is a flowchart illustrating the steps involved in constructing an arbitrary-order average value model in one embodiment.

[0048] Figure 7 A schematic diagram comparing the output voltage waveforms of an arbitrary-order average value model obtained by an embodiment of the average value model construction method with other models;

[0049] Figure 8 A schematic diagram comparing the inductor current waveform of an arbitrary-order average model obtained by the average model construction method of one embodiment with other models;

[0050] Figure 9 This is a structural block diagram of an average value model construction device in one embodiment;

[0051] Figure 10 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0053] The average value model construction method provided in this application embodiment can be used for, for example, Figure 1 The dual active full-bridge converter shown is used to construct a general arbitrary-order average value model.

[0054] like Figure 1 As shown, the dual active full-bridge converter includes an input voltage source v1, an input capacitor C1, a first-order H-bridge switch composed of four switching elements (S1, S2, S3, and S4), and R... S The equivalent resistance R is composed of the parasitic resistance of the conductor and the on-resistance of the switch.s The equivalent inductance L, composed of a high-frequency transformer, transformer leakage inductance, and auxiliary inductance, is... s The system consists of a second-order H-bridge switch composed of four switching elements (S5, S6, S7 and S8), an output capacitor C2, and an output resistor R2.

[0055] In this embodiment, the switching element of the first-order H-bridge switch can be a field-effect transistor or a transistor, and the switching element of the second-order H-bridge switch can also be a field-effect transistor or a transistor. This embodiment does not limit the specific type of switching element, and can be configured according to the needs of the actual application scenario.

[0056] The output resistor R2 and the output current source i2 form the Norton equivalent circuit on the output side, and output the output voltage v2 of the dual active full-bridge converter.

[0057] The transformation ratio of the primary and secondary coils of the high-frequency transformer is N:1. It should be noted that the specific values ​​of each component in the dual active full-bridge converter in this embodiment can be adaptively replaced according to the needs of the actual application scenario; this embodiment does not limit this.

[0058] Furthermore, the average value model construction method proposed in this embodiment can be applied to various types of dual active full-bridge converters, and the specific circuit connection method of the dual active full-bridge converter can be adaptively replaced. Figure 1 This is for illustrative purposes only.

[0059] In the existing average value model construction process, due to the neglect of the dynamic characteristics of the inductor current, only a reduced-order average value model and a control-output small-signal model of the DC solid-state transformer can be obtained. These are used to analyze the steady-state and transient performance of the solid-state transformer, and to integrate a PI controller to achieve feedback and feedforward control, ensuring the system output performance. However, by only acquiring the DC characteristics of the output voltage, the model lacks the ability to represent the full time-frequency information of the inductor current and the multi-harmonic transmission characteristics of the output voltage.

[0060] Considering the DC component and first harmonic characteristics of the state variables, a general average value model for continuous-time domain DC solid-state transformers can be established. This model overcomes the drawback of traditional average value modeling, which requires the assumption of small ripple. Compared with the reduced-order model, it is more accurate in the low-frequency range and can reveal the influence of output capacitor ESR. However, it ignores the harmonic characteristics of solid-state transformers above the first harmonic, making it difficult to apply to the mechanism research and controller design scenarios of harmonics and broadband oscillations in solid-state transformer systems.

[0061] The average value model construction method proposed in this embodiment can be built on a general average value model of any order, which can be used to accurately characterize the harmonic components and DC components of solid-state transformers under the harmonic and broadband oscillation evolution law in high-proportion new energy DC microgrids.

[0062] In one embodiment, such as Figure 2 As shown, a method for constructing an average value model is provided, which can be applied to... Figure 1 Taking the dual active full-bridge converter in the example, the following steps are included:

[0063] Step 201: Analyze the single-phase-shift modulation waveform driving the dual active full-bridge converter based on the preset switching function to obtain the switching parameters under single-phase-shift modulation.

[0064] Specifically, in this embodiment, the preset switching functions include the switching parameter analysis functions corresponding to the first-order H-bridge switches and the switching parameter analysis functions corresponding to the second-order H-bridge switches. It should be noted that the preset switching functions can also be determined based on the switching circuit composition in the dual active full-bridge converter in the actual application scenario.

[0065] In practical applications, the dual active full-bridge converter is first modulated using a single phase-shift modulation method to analyze the switching characteristics of each H-bridge switch of the dual active full-bridge converter under the single phase-shift modulation waveform.

[0066] Specifically, the single-phase-shift modulation method can also be referred to as the modulation of a single-sideband (SSB) signal using the phase-shift method.

[0067] The specific steps for analyzing the single-phase-shift modulation waveform driving a dual active full-bridge converter include: within one switching cycle T s The switching behavior of first-order and second-order H-bridge switches is analyzed internally. The switching period T is... s For the switching frequency f s The reciprocal of the switching frequency f s It can be determined by obtaining the switching behavior of a first-order H-bridge switch or a second-order H-bridge switch under single-phase-shift modulation waveform driving.

[0068] Specifically, the switching parameters include the time the switch is in the on state and the time it is in the off state within a switching cycle.

[0069] In one embodiment, step 201 specifically involves analyzing the single-phase-shift modulation waveform based on the primary H-bridge switching function and the secondary H-bridge switching function to obtain the switching parameters.

[0070] The H-bridge switching function includes:

[0071]

[0072] The secondary H-bridge switching functions include:

[0073]

[0074] Where g1(t) is a first-order H-bridge switching function, n is an integer, and T s d is the switching period; g5(t) is the secondary H-bridge switching function; d is the phase shift ratio of the primary H-bridge switch and the secondary H-bridge switch in the dual active full-bridge converter; and t is the time variable.

[0075] In a specific embodiment, the switching characteristic waveforms of g1(t) and g5(t) driven by a single-phase-shift modulation waveform are shown in the figure below. Figure 3 As shown. Among them, The waveform shown is g1(t), which represents the switching characteristics. The waveform shown is g5(t), which represents the switching characteristics.

[0076] Step 202: Construct the corresponding target state equation based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0077] Specifically, the target state equation is the state equation corresponding to the state variables obtained by the average value model. In this embodiment, the state variables obtained by the average value model of any order include the inductor current state variable and the output voltage state variable. The target state equation includes the inductor current state equation and the output voltage state equation.

[0078] In a specific embodiment, the switching parameters of the first-order H-bridge switch and the second-order H-bridge switch need to be fully considered during the construction of the target state equation, and the equation is constructed in combination with the circuit parameters of the dual active full-bridge converter.

[0079] The circuit parameters include the inductor current i L Input voltage v1, output voltage v2, output current i2, output resistance R2, output capacitance C2, and transformer equivalent inductance L. s Equivalent resistance R of wire switch S And the transformation ratio N of the primary and secondary windings of the transformer.

[0080] Step 203: Perform Fourier decomposition on the non-sinusoidal signals corresponding to the target state variables within the switching cycle according to the Fourier series decomposition equation to obtain the target sinusoidal components to be solved.

[0081] Specifically, the Fourier series decomposition equation is shown below:

[0082]

[0083] Where x(τ) is the time-varying signal to be decomposed, and τ represents the time interval. <x> k (t) represents the coefficients of the k-th Fourier series of the time-varying signal to be decomposed, j is the imaginary unit, k is the harmonic order, and ω s ω is the angular frequency.

[0084] Specifically, the time interval τ is within the switching period T. s Inside.

[0085] In practical applications, the time-varying signal corresponding to the target state variable within the switching cycle is used as x(τ) for Fourier decomposition to obtain the DC component and harmonic component to be solved.

[0086] Step 204: Solve the equations using the k-th degree coefficients of the Fourier series, and solve for the k-th degree coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables.

[0087] In a specific embodiment, the equation for solving the k-th degree coefficients of the Fourier series is as follows:

[0088]

[0089] Where x(τ) is the time-varying signal to be decomposed, τ represents the time interval, and T s For the switching cycle, <x> k (t) represents the coefficients of the k-th Fourier series of the time-varying signal to be decomposed, j is the imaginary unit, k is the harmonic order, and ω s ω is the angular frequency.

[0090] Specifically, this embodiment calculates the k-th order coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables, which enables the average value model to characterize the high-frequency characteristics of the system when constructing an average value model of arbitrary order. This helps the average value model to be further applied to controller design and system stability assessment.

[0091] Step 205: Based on the switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation, construct an arbitrary order average value model.

[0092] Specifically, an arbitrary-order average value model is constructed by comprehensively acquiring the switching parameters, the k-coefficients of the Fourier series corresponding to the switching parameters, the DC components and harmonic components corresponding to each target state variable to be solved, the multinomial circuit parameters and state variable parameters in the target state equation, and the k-order coefficients of the Fourier series corresponding to the target state variables.

[0093] In summary, this embodiment proposes an average value model construction method that considers higher harmonic components to improve the accuracy of the average value model of the dual active full-bridge converter, which can accurately characterize the inductor current and output voltage ripple.

[0094] In one embodiment, such as Figure 4 As shown, step 202 includes:

[0095] Step 401: Construct the inductor current state equation based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0096] Specifically, the inductor current state equation is as follows:

[0097]

[0098] Among them, i L V1 is the inductor current, V2 is the input voltage, and R is the output voltage. S L is the equivalent resistance composed of the parasitic resistance of the conductor and the on-resistance of the switch. S G1 is the equivalent inductance composed of the transformer leakage inductance and auxiliary inductance, g5 is the switching parameter of the primary H-bridge switch, g5 is the switching parameter of the secondary H-bridge switch, and N is the transformation ratio of the primary and secondary windings of the transformer.

[0099] Step 402: Construct the output voltage state equation based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0100] Specifically, the output voltage state equation is as follows:

[0101]

[0102] Among them, i L V1 represents the inductor current, V2 represents the output voltage, R2 represents the output resistance, i2 represents the output current, g1 represents the switching parameters of the primary H-bridge switch, g5 represents the switching parameters of the secondary H-bridge switch, N represents the transformation ratio of the primary and secondary windings of the transformer, and C2 represents the output capacitor.

[0103] In this embodiment, by constructing the inductor current state equation and the output voltage state equation, it is possible to describe the dynamic and static characteristics of the inductor current and the output voltage.

[0104] In one embodiment, such as Figure 5 As shown, step 203 includes:

[0105] Step 501: Perform Fourier decomposition on the non-sinusoidal signal corresponding to the inductor current state variable during the switching cycle according to the Fourier series decomposition equation to obtain the DC component and harmonic component of the inductor current state variable to be solved.

[0106] Step 502: Perform Fourier decomposition on the non-sinusoidal signals corresponding to the output voltage state variables during the switching cycle according to the Fourier series decomposition equation to obtain the DC component and harmonic component of the output voltage state variables to be solved.

[0107] In practical applications, the time-varying signals corresponding to the inductor current state variable and the output voltage state variable during the switching cycle are respectively used as x(τ) for Fourier decomposition to obtain the DC component and harmonic component corresponding to the inductor current state variable to be solved, and the DC component and harmonic component corresponding to the output voltage state variable to be solved.

[0108] In one embodiment, solving the equation based on the k-th order coefficients of the Fourier series, and solving for the k-th order coefficients of the Fourier series corresponding to the switch switching parameters and the target state variable, includes:

[0109] Solve the equations using the k-th order coefficients of the Fourier series, and find the k-th order coefficients of the Fourier series corresponding to the switching parameters, inductor current state variables, and output voltage state variables.

[0110] In one embodiment, such as Figure 6 As shown, step 205 includes:

[0111] Step 601: Based on the multinomial parameters of the target state equation and the k-th order coefficients of the Fourier series, obtain the coefficients of the first state equation, the coefficients of the second state equation, and the coefficients of the third state equation.

[0112] In a specific embodiment, the coefficients of the first state equation are shown in the following formula:

[0113]

[0114] Where A represents the coefficients of the first state equation, a represents an element in matrix A, where the first subscript number indicates the row number, the second subscript number indicates the column number, and k... i This represents the k-th harmonic component of the inductor current. v This represents the kth harmonic component of the output voltage state variable.

[0115] The coefficients of the second state equation are shown in the following formula:

[0116]

[0117] Where B represents the coefficients of the second state equation, b represents an element in matrix B, where the first subscript indicates the row number, the second subscript indicates the column number, and k... i L represents the k-th harmonic component of the inductor current. S This represents the equivalent inductance consisting of the transformer leakage inductance and auxiliary inductance. C2 represents the output capacitance value.

[0118] The coefficients of the third state equation are shown in the following formula:

[0119]

[0120] Where C is the coefficient of the third state equation, k i ω represents the k-th harmonic component of the inductor current. s ω is the angular frequency. s =2π / T S τ is the time interval.

[0121] Step 602: Obtain the input variables based on the input voltage and the output current;

[0122] Specifically, the input variables are shown in the following formula:

[0123] u = [V1, I2] T ;

[0124] Where u is the input variable, V1 is the input voltage, and I2 is the output current.

[0125] Step 603: Obtain the independent variables based on the target sinusoidal component to be solved;

[0126] Specifically, the independent variable is shown in the following formula:

[0127]

[0128] in, This represents the DC component and harmonic components of the inductor current. The superscript R indicates the real part, the superscript I indicates the imaginary part, the subscript 0 indicates the DC component, and the subscript k represents the DC component. i k represents the inductor current i Second harmonic components; This represents the DC component and harmonic components of the output voltage. The superscript R indicates the real part, the superscript I indicates the imaginary part, the subscript 0 indicates the DC component, and the subscript k indicates the DC component. v k represents the output voltage v Second harmonic components;

[0129] Step 604: Determine the output variables based on the inductor current and output voltage;

[0130] Specifically, the output variables are shown in the following formula:

[0131] y = [i L v2] T ;

[0132] Among them, i L V1 represents the inductor current of the dual active full-bridge converter; V2 represents the output voltage of the dual active full-bridge converter.

[0133] Step 605: Construct an arbitrary-order average value model based on the coefficients of the first state equation, the coefficients of the second state equation, the coefficients of the third state equation, the input variables, the independent variables, and the output variables.

[0134] Specifically, the average value model of any order is shown in the following formula:

[0135]

[0136] Where x represents the DC and harmonic components of the inductor current and output voltage state variables to be solved; y represents the solved inductor current and output voltage state variables; u represents the input variable; and A, B, and C represent the coefficients of the first, second, and third state equations, respectively, corresponding to the state equations.

[0137] In constructing an arbitrary-order average value model, this embodiment not only solves for the harmonic components of the inductor current state variable and the output voltage state variable, but also reconstructs the inductor current and output voltage state variables that need to be solved through Fourier series reconstruction.

[0138] In summary, this embodiment proposes an average value model construction method, including a primary H-bridge switching function and a secondary H-bridge switching function, which can characterize the switching characteristics of a dual active full-bridge converter under single-phase-shift modulation. It constructs the inductor current state equation and the output voltage equation, which can characterize the dynamic and static characteristics of the inductor current and output voltage. Through Fourier series decomposition of the equation, the periodic non-sinusoidal signal is decomposed to obtain sinusoidal components at different frequencies, facilitating solution and processing. The k-th order coefficients of the Fourier series are obtained by solving the equation using the k-th order coefficients of the Fourier series, yielding the switching parameters, inductor current, and output voltage. An arbitrary-order average value model is constructed, which can solve for the harmonic components of the target state variable and reconstruct the specific values ​​of the target state variable. The arbitrary-order average value model constructed in this embodiment is a continuous-time model, which is simpler than the discrete-time model, has a clearer physical meaning, and can accurately characterize the high-frequency characteristics of the system, inductor current, and output voltage ripple, effectively improving the efficiency and accuracy of controller design and system stability assessment.

[0139] In a more detailed embodiment, the average value model construction method proposed in this embodiment may include the following steps:

[0140] 1. Analyze the single-phase modulation waveform of the dual active full-bridge converter under the single-phase modulation method, and establish the switching functions of the primary H-bridge switch and the secondary H-bridge switch based on the analysis results. These functions are used to characterize the switching parameters of the primary H-bridge switch and the secondary H-bridge switch.

[0141] 2. Establish the inductor current state equation and the output voltage state equation of the dual active full-bridge converter. The inductor current state equation is used to describe the dynamic and static characteristics of the inductor current, and the output voltage state equation is used to describe the dynamic and static characteristics of the output voltage.

[0142] 3. By performing Fourier decomposition on the inductor current state variable and the output voltage state variable, the harmonic components of the inductor current and the output voltage at different frequencies are obtained.

[0143] 4. Solve the equations using the k-th order coefficients of the Fourier series to obtain the k-th order coefficients of the Fourier series for the switching parameters, inductor current, and output voltage.

[0144] 5. Construct an arbitrary-order average value model, solve for the harmonic components of the inductor current state variable and the output voltage state variable, and reconstruct the inductor current and output voltage using Fourier series.

[0145] like Figure 7 and Figure 8 As shown, this invention also discloses simulation results based on MATLAB / Simulink in a specific embodiment. Specifically, in the corresponding single-phase-shift modulated wave, the switching signal is a square wave with a duty cycle of 50%, wherein the switching signal of the primary H-bridge leads the switching signal of the secondary H-bridge by a time dT. S / 2, the waveform shape of the inductor current changes with the shift ratio d.

[0146] In a dual active full-bridge converter system with an input voltage v1 of 60V, an arbitrary-order average value model of the corresponding dual active full-bridge converter is constructed based on the average value model construction method of this example. The output voltage v2 is set to 65.4V, the phase shift ratio d is set to 0.2, the turns ratio of the primary and secondary coils of the high-frequency transformer is set to 1:1, and the switching frequency f is set to... S To set the frequency to 10kHz, the equivalent inductance was set to 316.5μH, the equivalent resistance to 1.5Ω, the output load resistance R2 to 45.0Ω, and the output filter C2 to 55.7μF. The MATLAB / Simulink simulation results are as follows: Figure 7 and Figure 8 As shown, the average voltage differences of the reduced-order model, the general average value model, the improved reduced-order model, the arbitrary-order average value model (k=2), and the arbitrary-order average value model (k=7) are 4.390%, 4.499%, 0.045%, 4.268%, and 0.254%, respectively. It can be seen that the arbitrary-order average value model constructed based on the average value model construction method in this example can accurately characterize the DC component of the output voltage.

[0147] Among them, the reduced-order model, the general average value model, and the improved reduced-order model ignore the output voltage ripple, while the arbitrary-order average value model (k=2) and the arbitrary-order average value model (k=7) constructed in this embodiment can characterize the output voltage ripple, and their ripple voltage similarity is 0.8666 and 0.9763, respectively.

[0148] The reduced-order model and the improved reduced-order model ignore inductor current in the modeling process, and therefore cannot characterize inductor current ripple. The inductor current similarity of the general average model and the arbitrary-order average model (k=2) and arbitrary-order average model (k=7) constructed in this embodiment are 0.9516, 0.9516, and 0.9954, respectively. Therefore, the arbitrary-order average model constructed by the average model construction method in this example can achieve accurate modeling of inductor current.

[0149] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0150] Based on the same inventive concept, this application also provides an average value model construction apparatus for implementing the above-described average value model construction method. The solution provided by this apparatus is similar to the implementation scheme described in the above method; therefore, the specific limitations in one or more average value model construction apparatus embodiments provided below can be found in the limitations of the average value model construction method described above, and will not be repeated here.

[0151] In one embodiment, such as Figure 9 As shown, an average value model construction device 900 is provided, including: a waveform analysis module 910, a state equation construction module 920, a Fourier decomposition module 930, a coefficient calculation module 940, and a model construction module 950, wherein:

[0152] The waveform analysis module 910 is used to analyze the single-phase-shift modulation waveform driving the dual active full-bridge converter based on a preset switching function, so as to obtain the switching parameters under single-phase-shift modulation.

[0153] The state equation construction module 920 is used to construct the corresponding target state equation based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0154] The Fourier decomposition module 930 is used to perform Fourier decomposition on the non-sinusoidal signals corresponding to the target state variables within the switching cycle according to the Fourier series decomposition equation, so as to obtain the target sinusoidal components to be solved.

[0155] The coefficient calculation module 940 is used to solve equations based on the k-th degree coefficients of the Fourier series, and to solve for the k-th degree coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables.

[0156] Model building module 950 is used to construct an average value model of arbitrary order based on switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation.

[0157] In one embodiment, the waveform analysis module 910 is specifically used to analyze the single-phase-shift modulation waveform based on the primary H-bridge switching function and the secondary H-bridge switching function to obtain the switching parameters.

[0158] In one embodiment, the state equation construction module 920 is specifically used to construct the inductor current state equation based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0159] The output voltage state equation is constructed based on the switching parameters and the circuit parameters of the dual active full-bridge converter. The switching parameters include the switching parameters of the primary H-bridge switch and the switching parameters of the secondary H-bridge switch. The circuit parameters include inductor current, input voltage, output voltage, output current, output resistance, output capacitance, transformer equivalent inductance, wire switch equivalent resistance, and the transformation ratio of the primary and secondary windings of the transformer.

[0160] In one embodiment, the Fourier decomposition module 930 is specifically used to perform Fourier decomposition on the non-sinusoidal signal corresponding to the inductor current state variable within the switching cycle according to the Fourier series decomposition equation, so as to obtain the DC component and harmonic component of the inductor current state variable to be solved.

[0161] Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the output voltage state variables within the switching cycle are decomposed using Fourier decomposition to obtain the DC component and harmonic components of the output voltage state variables to be solved.

[0162] In one embodiment, the coefficient calculation module 940 is specifically used to solve the equation based on the k-th order coefficients of the Fourier series, and to solve for the k-th order coefficients of the Fourier series corresponding to the switch switching parameters, inductor current state variables, and output voltage state variables.

[0163] In one embodiment, the model building module 950 is specifically used to obtain the coefficients of the first state equation, the coefficients of the second state equation, and the coefficients of the third state equation based on the multinomial parameters of the target state equation and the k-th order coefficients of the Fourier series; to obtain the input variables based on the input voltage and the output current; to obtain the independent variables based on the target sinusoidal component to be solved; to determine the output variables based on the inductor current and the output voltage; and to construct an arbitrary-order average value model based on the coefficients of the first state equation, the coefficients of the second state equation, the coefficients of the third state equation, the input variables, the independent variables, and the output variables.

[0164] Each module in the aforementioned average value model construction device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the operations corresponding to each module.

[0165] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 10 As shown, the computer device includes a processor, memory, input / output interfaces, a communication interface, a display unit, and an input device. The processor, memory, and input / output interfaces are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The input / output interfaces are used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements an average value model construction method. The display unit is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0166] Those skilled in the art will understand that Figure 10 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0167] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0168] Based on the analysis of the single-phase-shift modulation waveform of the dual active full-bridge converter driven by the preset switching function, the switching parameters under single-phase-shift modulation are obtained.

[0169] The target state equation is constructed based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0170] Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the target state variables within the switching cycle are decomposed using Fourier decomposition to obtain the target sinusoidal components to be solved.

[0171] Solve the equations using the k-th degree coefficients of the Fourier series, and find the k-th degree coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables.

[0172] Based on the switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation, an arbitrary-order average value model is constructed.

[0173] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0174] Based on the analysis of the single-phase-shift modulation waveform of the dual active full-bridge converter driven by the preset switching function, the switching parameters under single-phase-shift modulation are obtained.

[0175] The target state equation is constructed based on the switching parameters and the circuit parameters of the dual active full-bridge converter.

[0176] Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the target state variables within the switching cycle are decomposed using Fourier decomposition to obtain the target sinusoidal components to be solved.

[0177] Solve the equations using the k-th degree coefficients of the Fourier series, and find the k-th degree coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables.

[0178] Based on the switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation, an arbitrary-order average value model is constructed.

[0179] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0180] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0181] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.< / x> < / x>

Claims

1. A method for constructing an average value model, characterized in that, The method for creating an arbitrary-order average value model for a dual active full-bridge converter includes: Based on the analysis of the single-phase-shift modulation waveform driving the dual active full-bridge converter using a preset switching function, the switching parameters under single-phase-shift modulation are obtained. Based on the switching parameters and the circuit parameters of the dual active full-bridge converter, a corresponding target state equation is constructed. Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the target state variables within the switching cycle are decomposed using Fourier decomposition to obtain the target sinusoidal components to be solved. Solve the equations using the k-th order coefficients of the Fourier series, and then solve for the k-th order coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables. Based on the switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation, an arbitrary order average value model is constructed. The step of analyzing the single-phase-shift modulation waveform driving the dual active full-bridge converter based on a preset switching function to obtain the switching parameters under single-phase-shift modulation includes: The single-phase-shift modulation waveform is analyzed based on the primary H-bridge switching function and the secondary H-bridge switching function to obtain the switching parameters; The construction of an arbitrary-order average value model based on the switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation includes: Based on the multiple parameters of the target state equation and the k-th degree coefficients of the Fourier series, the coefficients of the first state equation, the coefficients of the second state equation, and the coefficients of the third state equation are obtained. The input variables are obtained based on the input voltage and the output current. Based on the target sinusoidal component to be solved, the independent variable is obtained; The output variables are determined based on the inductor current and the output voltage. The arbitrary-order average value model is constructed based on the coefficients of the first state equation, the coefficients of the second state equation, the coefficients of the third state equation, the input variable, the independent variable, and the output variable. The model for the average value of any order is shown in the following formula: ； in, The DC and harmonic components of the inductor current and output voltage state variables to be solved are: To obtain the inductor current and output voltage state variables; is the input variable; A, B, and C are the coefficients of the first, second, and third state equations, respectively, corresponding to the state equations.

2. The method according to claim 1, characterized in that, The primary H-bridge switching function includes: ； The secondary H-bridge switching function includes: ； in, For the first-order H-bridge switching function, It is an integer. For switching cycles; The second-order H-bridge switching function, The phase shift ratio of the primary H-bridge switch and the secondary H-bridge switch in the dual active full-bridge converter is given. It is a time variable.

3. The method according to claim 2, characterized in that, The construction of the corresponding target state equation based on the switching parameters and the circuit parameters of the dual active full-bridge converter includes: The inductor current state equation is constructed based on the switching parameters and the circuit parameters of the dual active full-bridge converter. The output voltage state equation is constructed based on the switching parameters and the circuit parameters of the dual active full-bridge converter. The switching parameters include the switching parameters of the primary H-bridge switch and the switching parameters of the secondary H-bridge switch. The circuit parameters include inductor current, input voltage, output voltage, output current, output resistance, output capacitance, transformer equivalent inductance, wire switch equivalent resistance, and the transformation ratio of the primary and secondary windings of the transformer.

4. The method according to claim 3, characterized in that, The step of performing Fourier decomposition on the non-sinusoidal signals corresponding to the target state variables within the switching cycle according to the Fourier series decomposition equation to obtain the target sinusoidal components includes: Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the inductor current state variables within the switching cycle are decomposed using Fourier decomposition to obtain the DC component and harmonic component of the inductor current state variables to be solved. Based on the Fourier series decomposition equation, the non-sinusoidal signals corresponding to the output voltage state variables within the switching cycle are decomposed using Fourier decomposition to obtain the DC component and harmonic components of the output voltage state variables to be solved.

5. The method according to claim 4, characterized in that, The step of solving the equation based on the k-th order coefficients of the Fourier series, and solving for the k-th order coefficients of the Fourier series corresponding to the switch switching parameters and the target state variable, includes: Solve the equations using the k-th order coefficients of the Fourier series to determine the k-th order coefficients of the Fourier series corresponding to the switching parameters, the inductor current state variable, and the output voltage state variable.

6. An apparatus for constructing an average value model, characterized in that, The apparatus for creating an arbitrary-order average value model for a dual active full-bridge converter includes: The waveform analysis module is used to analyze the single-phase-shift modulation waveform driving the dual active full-bridge converter based on a preset switching function, so as to obtain the switching parameters under single-phase-shift modulation. The state equation construction module is used to construct the corresponding target state equation based on the switch switching parameters and the circuit parameters of the dual active full-bridge converter. The Fourier decomposition module is used to perform Fourier decomposition on the non-sinusoidal signals corresponding to the target state variables within the switching cycle according to the Fourier series decomposition equation, so as to obtain the target sinusoidal components to be solved. The coefficient calculation module is used to solve the equation based on the k-th degree coefficients of the Fourier series, and to solve for the k-th degree coefficients of the Fourier series corresponding to the switch switching parameters and the target state variables. The model building module is used to construct an arbitrary-order average value model based on the switch switching parameters, the target sinusoidal component to be solved, the k-th order coefficients of the Fourier series, and the multinomial parameters of the target state equation. The waveform analysis module is also used to analyze the single-phase-shift modulation waveform based on the primary H-bridge switching function and the secondary H-bridge switching function to obtain the switching parameters; The model building module is also used to obtain the coefficients of the first state equation, the coefficients of the second state equation, and the coefficients of the third state equation based on the multiple parameters of the target state equation and the k-th degree coefficients of the Fourier series. The input variables are obtained based on the input voltage and the output current. Based on the target sinusoidal component to be solved, the independent variable is obtained; The output variables are determined based on the inductor current and the output voltage. The arbitrary-order average value model is constructed based on the coefficients of the first state equation, the coefficients of the second state equation, the coefficients of the third state equation, the input variable, the independent variable, and the output variable. The model for the average value of any order is shown in the following formula: ； in, The DC and harmonic components of the inductor current and output voltage state variables to be solved are: To obtain the inductor current and output voltage state variables; is the input variable; A, B, and C are the coefficients of the first, second, and third state equations, respectively, corresponding to the state equations.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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