Charging module impedance modeling method and system of electric vehicle charging pile

Abstract

The invention discloses a charging module impedance modeling method and system for an electric vehicle charging pile, and the method comprises the steps: enabling an AC system to be equivalent to a DC system through abc / dq coordinate transformation, obtaining a DC working point, introducing disturbance on the DC working point, and building a small signal model of a front-stage VIENNA rectifier; the method comprises the following steps: dividing a circuit into independent sub-modules based on an equivalent circuit method, performing small signal analysis on each sub-module, and then establishing a small signal model of a post-stage full-bridge LLC resonant converter; according to the small-signal model of the front-stage VIENNA rectifier and the small-signal model of the rear-stage full-bridge LLC resonant converter, an overall small-signal model is established in combination with the front-stage and rear-stage control strategies; the output impedance transfer function and the voltage and current transfer function of the front and back stages are calculated through the overall small signal model, and then the impedance model of the charging module is obtained, so that a foundation is laid for subsequent analysis of the stability of the parallel charging module; and establishing a system simulation model in the platform to verify the impedance model of the charging module.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic system modeling, and in particular to a charging module impedance modeling method and system for an electric vehicle charging pile. Background Art

[0002] Accelerate the promotion and popularization of electric vehicles and initially form a new energy vehicle industry system. These measures will help reduce dependence on traditional oil energy and promote environmental protection and sustainable development.

[0003] As a key supporting facility for electric vehicles, the topology of the charging module inside the electric vehicle charging pile is one of the key factors that determine the system performance. At present, the high-power charging module in the charging pile usually adopts a two-stage conversion structure. The front-stage AC / DC link adopts a three-phase rectifier circuit, which is responsible for rectification and active power factor correction; the rear-stage DC / DC link adopts a phase-shifted full-bridge converter or LLC resonant converter, which is responsible for electrical isolation and voltage conversion. Among them, the VIENNA rectifier has excellent characteristics such as low switching stress, high power density, and high reliability under the same level number, and is widely used in the front stage of the charging module. The full-bridge LLC resonant converter has the advantages of simple topology and high power density, and is widely used in the rear stage of the charging module.

[0004] Since high-power DC charging uses a structure where multiple charging modules work in parallel, the limitations of process level and differences in component characteristics will lead to instability after parallel connection. Impedance analysis is an effective means to solve or prevent this problem, but there is no report on the impedance modeling method for the DC charging module, a two-stage system. Therefore, in order to solve the above technical problems, it is urgent to propose a method to carry out impedance modeling of the two-stage DC charging module. Summary of the invention

[0005] The purpose of the present invention is to provide a charging module impedance modeling method and system for an electric vehicle charging pile. First, a small signal model of the front-stage VIENNA rectifier and the rear-stage full-bridge LLC resonant converter of the charging module is established. Then, the small signal model of the charging module is constructed by combining the control strategies of the front and rear stages, and then the impedance model of the charging module is derived. Compared with the previous methods, the innovation of the present invention is that the impedance model of the charging module inside the electric vehicle charging pile is established, which lays the foundation for the subsequent analysis of the stability of the parallel charging module.

[0006] Therefore, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a charging module impedance modeling method for an electric vehicle charging pile, comprising: obtaining a DC operating point after converting an AC system into a DC system through coordinate transformation, introducing a disturbance at the DC operating point to establish a small signal model of a front-stage VIENNA rectifier of the charging module; dividing the circuit into independent sub-modules based on an equivalent circuit method, and establishing a small signal model of a rear-stage full-bridge LLC resonant converter of the charging module after performing small signal analysis on each sub-module; establishing an overall small signal model of the charging module based on the small signal model of the front-stage VIENNA rectifier of the charging module and the small signal model of the rear-stage full-bridge LLC resonant converter of the charging module, in combination with the control strategy of the front and rear stages of the charging module; calculating the output impedance transfer function and the voltage-current transfer function of the front and rear stages through the overall small signal model of the charging module, and obtaining the impedance model of the charging module based on the output impedance transfer function and the voltage-current transfer function of the front and rear stages.

[0008] As a preferred solution of the charging module impedance modeling method of the electric vehicle charging pile described in the present invention, wherein: the small signal model of the front-stage VIENNA rectifier of the charging module is established, including:

[0009] According to the topological structure of the VIENNA rectifier in the front stage of the charging module, the circuit loop equation is written as:

[0010]

[0011] Among them, u x (x=a,b,c) represents the three-phase AC grid voltage, i x (x=a,b,c) represents the three-phase output current, L represents the AC side boost inductor, R represents the inductor parasitic resistance, U xO (x=a,b,c) represents the voltage of the input terminal relative to the DC midpoint O, U ON It represents the voltage of the DC side midpoint O relative to the neutral point N of the three-phase AC power grid, C represents the DC output side filter capacitor, u C1 and u C2 Represent the voltage of capacitors C1 and C2 respectively, i C1 and i C2 Respectively represent the current flowing through capacitors C1 and C2, s x Indicates the switching state of the xth phase;

[0012] Define the threshold function sgni x (x=a, b, c) and the rectifier bridge voltage on the AC side, and the circuit loop equation of the front-stage VIENNA rectifier topology of the charging module is linearized by the switching cycle averaging method, which is expressed as:

[0013]

[0014] Among them, V o Indicates the effective value of the DC side output voltage of the previous stage VIENNA rectifier, u Nx (x=a,b,c) represents the phase voltage of the power grid, d x (x=a,b,c) represents the duty cycle;

[0015] The three-phase stationary abc coordinate system is transformed into a two-phase synchronous rotating dq coordinate system through Park transformation. After the dq coordinate system is decoupled, the state equation corresponding to the front-stage VIENNA rectifier of the charging module is:

[0016]

[0017] The DC operating point obtained is:

[0018]

[0019] Among them, U d ,I d , D d , D q All are steady-state operating points, I s and U s Respectively represent the RMS value of grid-side current and grid voltage, i d 、i q represents the steady-state current in dq coordinates, U dc represents the steady-state output voltage, i dc Represents the steady-state output current, ω o represents the operating angular frequency, d d d q represents the steady-state duty cycle in dq coordinates;

[0020] When the front-stage VIENNA rectifier of the charging module operates at unity power factor, the q-axis component is 0. A small disturbance is introduced at the stable operating point of the VIENNA rectifier and linearized. The linear small signal state equation of the VIENNA rectifier is obtained by ignoring the high-order terms:

[0021]

[0022] Among them, U dc represents the steady-state output voltage of the VIENNA rectifier, and “^” represents the disturbance amount;

[0023] A small signal model of the front-stage VIENNA rectifier of the charging module is established according to the linear small signal state equation of the VIENNA rectifier.

[0024] As a preferred solution of the charging module impedance modeling method of the electric vehicle charging pile described in the present invention, wherein: the establishment of the small signal model of the rear-stage full-bridge LLC resonant converter of the charging module includes:

[0025] The small signal model of the switch tube and the secondary rectifier diode of the full-bridge LLC resonant converter is:

[0026]

[0027] Among them, u k is the bridge arm output voltage, u dc is the output voltage of the VIENNA rectifier, i.e. the input voltage of the full-bridge LLC resonant converter, is the current flowing through the resonant inductor The real part, i in_LLC is the input current of the full-bridge LLC resonant converter, u R is the transformer primary voltage, R r and R i are the equivalent impedance of the real and imaginary parts of the primary side of the transformer, r is the equivalent impedance, and i t The real and imaginary parts, k r , k i is the coefficient, u o is the output voltage of the full-bridge LLC resonant converter;

[0028] The small signal model of the resonant inductor of the full-bridge LLC resonant converter is:

[0029]

[0030] Among them, L s is the resonant inductance, ω s represents the switching angular frequency, i Ls represents the current flowing through the resonant inductor, u Ls represents the voltage across the resonant inductor, Indicates i Ls The phasor form of

[0031] The small signal model of the magnetizing inductance of the full-bridge LLC resonant converter is:

[0032]

[0033] Among them, L m is the excitation magnetic inductance, i Lm represents the current flowing through the magnetizing inductor, Indicates i Lm The phasor form, u Lm Represents the voltage across the magnetizing inductor;

[0034] The small signal model of the resonant capacitor of the full-bridge LLC resonant converter is:

[0035]

[0036] Among them, C s is the resonant capacitor, i Cs represents the current flowing through the resonant capacitor, u Cs represents the voltage across the resonant capacitor, Indicates u Cs The phasor form of

[0037] When the switching frequency is much larger than the modulation frequency, the resonant network is simplified to an equivalent inductor in series, and the circuits are merged using the Thevenin and Norton branch equivalent transformation methods, reducing the system model order from the original seventh order to the third order.

[0038] When the full-bridge LLC resonant converter operates at a frequency slightly lower than the resonant frequency, R s / ω s L m The value of is approximately zero, at this time γ≈1, and the circuit loop equation is written as:

[0039]

[0040] Among them, L c is the simplified equivalent inductance, R s is the modulus of the impedance of the resonant inductor and the resonant capacitor.

[0041] As a preferred solution of the charging module impedance modeling method of the electric vehicle charging pile described in the present invention, the overall small signal model of the charging module is established by combining the control strategies of the front and rear stages of the charging module, including:

[0042] The front-stage VIENNA rectifier adopts dual closed-loop control including voltage outer loop and current inner loop control, wherein the voltage outer loop mainly adopts proportional integral controller, and the current inner loop mainly adopts feedforward decoupling control to eliminate cross coupling between dq axes;

[0043] According to the closed-loop control structure diagram:

[0044]

[0045] in, and They represent the output voltage reference value and d-axis current reference value of the VIENNA rectifier, G v1 represents the transfer function of the voltage loop controller, k pu1 , k pi1They represent the voltage loop proportional coefficient and integral coefficient respectively, s represents the complex frequency domain variable in Laplace transform, G i1 represents the transfer function of the current loop controller, Indicates the reference value of the q-axis current, k iu1 , k ii1 They represent the proportional coefficient and integral coefficient of the current loop respectively.

[0046] As a preferred solution of the charging module impedance modeling method of the electric vehicle charging pile described in the present invention, the overall small signal model of the charging module established by combining the control strategies of the front and rear stages of the charging module also includes:

[0047] The full-bridge LLC resonant converter control system adopts dual closed-loop control including voltage outer loop and current inner loop control. The voltage outer loop controls the voltage across the output capacitor, while the current inner loop controls the resonant inductor current.

[0048] According to the closed-loop control structure diagram:

[0049]

[0050]

[0051]

[0052] Among them, f s is the operating frequency, and They represent the full-bridge LLC resonant converter output voltage reference value and resonant inductor current reference value, G v2 represents the transfer function of the voltage loop controller, G i2 represents the transfer function of the current loop controller, k pu2 , k pi2 is the proportional coefficient and integral coefficient of the voltage loop, k iu2 , k ii2 are the proportional coefficient and integral coefficient of the current loop;

[0053] According to the small signal model of the front-stage VIENNA rectifier of the charging module and the small signal model of the rear-stage full-bridge LLC resonant converter of the charging module, an overall small signal model of the charging module is established in combination with the control strategies of the front- and rear-stages of the charging module.

[0054] As a preferred solution of the charging module impedance modeling method of the electric vehicle charging pile described in the present invention, the impedance model of the charging module is obtained according to the output impedance transfer function and the voltage and current transfer function of the front and rear stages, including:

[0055] The closed-loop output impedance of the front-stage VIENNA rectifier is:

[0056]

[0057] Among them, G 11 is the open-loop output impedance of the VIENNA rectifier, G 12 is the steady-state duty cycle of the d-axis d To output voltage u dc The transfer function, G c is the current loop open-loop transfer function;

[0058] The closed-loop output impedance of the subsequent full-bridge LLC resonant converter is:

[0059]

[0060] Where Z1 is the open-loop output impedance of the full-bridge LLC resonant converter, G uf is the transfer function from frequency to output voltage, G v2 represents the transfer function of the voltage loop controller, G Li is the transfer function from output current to inductor current, G lf is the transfer function from frequency to inductor current, T is the control loop gain;

[0061] The closed-loop control impedance model of the charging module is obtained according to the closed-loop output impedance of the front-stage VIENNA rectifier and the closed-loop output impedance of the rear-stage full-bridge LLC resonant converter:

[0062]

[0063] Among them, G vv is the transfer function from the VIENNA rectifier input voltage to the full-bridge LLC resonant converter output voltage, G ii is the transfer function from the full-bridge LLC resonant converter output current to the VIENNA rectifier input current, Y L is the input admittance of the full-bridge LLC resonant converter.

[0064] As a preferred solution of the charging module impedance modeling method of the electric vehicle charging pile of the present invention, wherein: building a system simulation model in the platform to verify the impedance model of the charging module includes:

[0065] A simulation model of the charging module is built, and a theoretically derived Bode plot is obtained based on the simulation parameters. When the charging module is operating stably, a disturbance current is injected and the amplitude and phase information of the disturbance current and the response disturbance voltage at each frequency point are extracted to obtain a simulated measured impedance Bode plot. The theoretically derived Bode plot is compared with the impedance Bode plot obtained by simulation measurement to obtain the result of impedance model verification of the charging module.

[0066] In a second aspect, the present invention provides a charging module impedance modeling system for an electric vehicle charging pile, comprising:

[0067] A charging module front-stage modeling unit, used to obtain a DC operating point after converting an AC system into a DC system through coordinate transformation, and introduce a disturbance at the DC operating point to establish a small signal model of a front-stage VIENNA rectifier of the charging module;

[0068] A charging module post-stage modeling unit, used to divide the circuit into independent sub-modules based on an equivalent circuit method, and establish a small signal model of the charging module post-stage full-bridge LLC resonant converter after performing small signal analysis on each sub-module;

[0069] The charging module overall modeling unit is used to establish an overall small signal model of the charging module according to the small signal model of the front-stage VIENNA rectifier of the charging module and the small signal model of the rear-stage full-bridge LLC resonant converter of the charging module, combined with the control strategies of the front-stage and rear-stage of the charging module;

[0070] The impedance model modeling unit is used to calculate the output impedance transfer function and the voltage-current transfer function of the front and rear stages through the overall small signal model of the charging module, and obtain the impedance model of the charging module according to the output impedance transfer function and the voltage-current transfer function of the front and rear stages.

[0071] In a third aspect, the present invention provides a computing device, comprising:

[0072] Memory and processor;

[0073] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the method are implemented.

[0074] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer-executable instructions, which implement the steps of the method when executed by a processor.

[0075] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention first establishes the small signal model of the front-stage VIENNA rectifier and the rear-stage full-bridge LLC resonant converter of the charging module, and then combines the control strategies of the front and rear stages to construct the small signal model of the charging module, and then derives the impedance model of the charging module, which lays the foundation for the subsequent analysis of the stability of the parallel charging module; and the feasibility and correctness of the charging module impedance modeling method of the electric vehicle charging pile proposed in the present invention are verified through simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0077] Figure 1 This is an overall flow chart of a charging module impedance modeling method for an electric vehicle charging pile according to an embodiment of the present invention;

[0078] Figure 2 A schematic diagram of a charging module circuit topology of a charging module impedance modeling method for an electric vehicle charging pile according to an embodiment of the present invention;

[0079] Figure 3 A schematic diagram of a VIENNA rectifier average model under dq rotating coordinates of a charging module impedance modeling method of an electric vehicle charging pile according to an embodiment of the present invention;

[0080] Figure 4 A schematic diagram of a VIENNA rectifier small signal circuit model of a charging module impedance modeling method of an electric vehicle charging pile according to an embodiment of the present invention;

[0081] Figure 5 A schematic diagram of a small signal model of a full-bridge LLC resonant converter according to a charging module impedance modeling method of an electric vehicle charging pile according to an embodiment of the present invention;

[0082] Figure 6 A block diagram of a VIENNA rectifier double closed-loop control transfer function of a charging module impedance modeling method of an electric vehicle charging pile according to an embodiment of the present invention;

[0083] Figure 7 A block diagram of a double closed-loop control transfer function of a full-bridge LLC resonant converter of a charging module impedance modeling method of an electric vehicle charging pile according to an embodiment of the present invention;

[0084] Figure 8 A schematic diagram of a charging module small signal model of a charging module impedance modeling method of an electric vehicle charging pile according to an embodiment of the present invention;

[0085] Fig. 9 A flowchart of an impedance measurement method for an impedance modeling method of a charging module of an electric vehicle charging pile according to an embodiment of the present invention;

[0086] Fig.10 The charging module impedance Bode diagram of the charging module impedance modeling method of the electric vehicle charging pile according to an embodiment of the present invention. DETAILED DESCRIPTION

[0087] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0088] Example 1

[0089] Reference Figures 1 to 8 According to an embodiment of the present invention, a charging module impedance modeling method for an electric vehicle charging pile is provided, which specifically includes the following steps:

[0090] S100: After converting the AC system into a DC system through abc / dq coordinate transformation, a DC operating point is obtained, and a disturbance is introduced at the DC operating point to establish a small signal model of the VIENNA rectifier in the front stage of the charging module;

[0091] It should be noted that since the VIENNA rectifier in the front stage of the charging module is a nonlinear system, it needs to be linearized. Therefore, the linearization of the equation is achieved by averaging the switching cycle. The AC system is equivalent to the DC system through the abc / dq coordinate transformation, and the DC operating point is obtained. Then, a disturbance is introduced at the DC operating point to obtain the small signal model of the VIENNA rectifier in the front stage of the charging module. To simplify the analysis process, the following two assumptions are made first: (1) The capacitance on the DC side is large enough, the DC voltage has no ripple in steady state, the midpoint potential is balanced and the three phases are strictly symmetrical; (2) The fundamental frequency on the AC side is much smaller than the switching frequency, and the grid-side current is in continuous mode.

[0092] In the embodiment of the present application, according to Figure 2 The circuit loop equation of the charging module front-stage VIENNA rectifier topology structure shown is:

[0093]

[0094] Among them, u x (x=a,b,c) represents the three-phase AC grid voltage, i x (x=a,b,c) represents the three-phase output current, L represents the AC side boost inductor, R represents the inductor parasitic resistance, U xO (x=a,b,c) represents the voltage of the input terminal relative to the DC midpoint O, U ON It represents the voltage of the DC side midpoint O relative to the neutral point N of the three-phase AC power grid, C represents the DC output side filter capacitor, and C1=C2=C, u C1 and u C2Represent the voltage of capacitors C1 and C2 respectively, i C1 and i C2 Respectively represent the current flowing through capacitors C1 and C2, s x Represents the switching state of the xth phase. The specific expression is:

[0095]

[0096] Furthermore, the threshold function sgni is defined x (x=a,b,c) is:

[0097]

[0098] The rectifier bridge voltage on the AC side is defined as:

[0099] u x =(1-s x )(sgni x u dc1 -(1-sgni x ) dc2 )

[0100] The circuit loop equation of the VIENNA rectifier topology of the front stage of the charging module is linearized by the switching cycle average method, which is expressed as:

[0101]

[0102] Among them, V o Indicates the effective value of the DC side output voltage of the previous stage VIENNA rectifier, u Nx (x=a,b,c) represents the phase voltage of the power grid, d x (x=a,b,c) represents the duty cycle;

[0103] Furthermore, the three-phase stationary abc coordinate system is transformed into a two-phase synchronous rotating dq coordinate system through Park transformation, and the formula is expressed as:

[0104]

[0105] After decoupling the dq coordinate system, the average model of the VIENNA rectifier in the front stage of the charging module is as follows: Figure 3 As shown, the corresponding state equation is:

[0106]

[0107] The DC operating point obtained is:

[0108]

[0109] Among them, U d ,Id , D d , D q All are steady-state operating points, I s and U s Respectively represent the RMS value of grid-side current and grid voltage, i d 、i q represents the steady-state current in dq coordinates, U dc represents the steady-state output voltage, i dc Represents the steady-state output current, ω o represents the operating angular frequency, d d d q represents the steady-state duty cycle in dq coordinates;

[0110] Furthermore, when the VIENNA rectifier in the front stage of the charging module works at unity power factor, the q-axis component is 0. A small disturbance is introduced at the stable working point of the VIENNA rectifier and linearized:

[0111]

[0112]

[0113] Ignoring the higher-order terms, the linear small-signal state equation of the VIENNA rectifier is:

[0114]

[0115] Among them, U dc represents the steady-state output voltage of the VIENNA rectifier, and “^” represents the disturbance amount;

[0116] According to the linear small signal state equation of the VIENNA rectifier, the small signal model of the front stage VIENNA rectifier of the charging module is established, such as Figure 4 shown.

[0117] S200: dividing the circuit into independent sub-modules based on an equivalent circuit method, and establishing a small signal model of the rear-stage full-bridge LLC resonant converter of the charging module after performing small signal analysis on each sub-module;

[0118] It should be noted that the full-bridge LLC resonant converter is Figure 2 As shown in the following figure, VD1-VD4 are primary switch tubes, L s is the resonant inductor, C s is the resonant capacitor, L m is the excitation magnetic inductance, T r For a transformer, the primary-secondary turns ratio is n, VD R1 -VD R4 is a diode, forming a secondary side rectifier circuit, C f is the output filter capacitor, Rld is the load resistance.

[0119] In the embodiment of the present application, the small signal model of the switch tube and the secondary rectifier diode of the full-bridge LLC resonant converter is:

[0120]

[0121]

[0122] Among them, u k is the bridge arm output voltage, u dc is the output voltage of the VIENNA rectifier, i.e. the input voltage of the full-bridge LLC resonant converter, is the current flowing through the resonant inductor The real part, i in_LLC is the input current of the full-bridge LLC resonant converter, u R is the transformer primary voltage, R r and R i are the equivalent impedance of the real and imaginary parts of the primary side of the transformer, r is the equivalent impedance, and They are The real and imaginary parts, k r , k i is the coefficient, u o is the output voltage of the full-bridge LLC resonant converter;

[0123] In the embodiment of the present application, the small signal model of the resonant inductor of the full-bridge LLC resonant converter is:

[0124]

[0125] Among them, L s is the resonant inductance, ω s represents the switching angular frequency, i Ls represents the current flowing through the resonant inductor, u Ls represents the voltage across the resonant inductor, Indicates i Ls The phasor form of

[0126] In the embodiment of the present application, the small signal model of the excitation inductance of the full-bridge LLC resonant converter is:

[0127]

[0128] Among them, L m is the excitation magnetic inductance, i Lm represents the current flowing through the magnetizing inductor, Indicates i Lm The phasor form, u LmRepresents the voltage across the magnetizing inductor;

[0129] In the embodiment of the present application, the small signal model of the resonant capacitor of the full-bridge LLC resonant converter is:

[0130]

[0131] Among them, C s is the resonant capacitor, i Cs represents the current flowing through the resonant capacitor, u Cs represents the voltage across the resonant capacitor, Indicates u Cs The phasor form of

[0132] It should be noted that the resonant converter has a unique feature. When the switching frequency is much larger than the modulation frequency, the parallel complex impedance capacitor can be simplified to a series equivalent inductor. The two have the same complex impedance, and the inductance value is determined by the switching frequency and the capacitance value. Based on this discovery, the resonant network can be simplified, and the circuit can be merged using the Thevenin and Norton branch equivalent transformation method. The system model order is reduced from the original seventh order to the third order, such as Figure 5 As shown;

[0133] Figure 5 in,i in-llc is the input current of the full-bridge LLC resonant converter, u dc is the output voltage of the VIENNA rectifier, i.e. the input voltage of the full-bridge LLC resonant converter, L c is the simplified equivalent inductance, R e is the load resistance R ld The resistance equivalent to the primary side of the transformer, R q For R e and L m The impedance amplitude after parallel equivalent, R s is the modulus of the impedance of the resonant inductor and capacitor, and X is R q and R e The sum of the impedances, R r , R i and r is the equivalent reactance of the primary side of the transformer, and They are The real and imaginary parts, U Cs-r and U Cs-i They are The real and imaginary parts, I Ls-r and I Ls-i I Ls The real and imaginary parts, I Lm-r and I Lm-i They are The real and imaginary parts of ω sis the switching angular frequency, k r , k i , γ are coefficients, and the specific parameter expressions are as follows

[0134]

[0135] Furthermore, when the full-bridge LLC resonant converter operates at a frequency slightly lower than the resonant frequency, R s / ω s L m The value of is approximately zero, at this time γ≈1, and the circuit loop equation is written as:

[0136]

[0137] Among them, L c is the simplified equivalent inductance, R s is the modulus of the impedance of the resonant inductor and the resonant capacitor.

[0138] S300: establishing an overall small signal model of the charging module according to the small signal model of the VIENNA rectifier at the front stage of the charging module and the small signal model of the full-bridge LLC resonant converter at the rear stage of the charging module, combined with the control strategies of the front and rear stages of the charging module;

[0139] In the embodiment of the present application, the front-stage VIENNA rectifier adopts dual closed-loop control including voltage outer loop and current inner loop control, wherein the voltage outer loop mainly adopts proportional integral controller, and the current inner loop mainly adopts feedforward decoupling control to eliminate the cross coupling between dq axes. The transfer function block diagrams are as follows: Figure 6 As shown;

[0140] According to the closed-loop control structure diagram:

[0141]

[0142] in, and They represent the output voltage reference value and d-axis current reference value of the VIENNA rectifier, G v1 represents the transfer function of the voltage loop controller, k pu1 , k pi1 They represent the voltage loop proportional coefficient and integral coefficient respectively, s represents the complex frequency domain variable in Laplace transform, G i1 represents the transfer function of the current loop controller, Indicates the reference value of the q-axis current, k iu1 , k ii1 They represent the proportional coefficient and integral coefficient of the current loop respectively.

[0143] In the embodiment of the present application, the full-bridge LLC resonant converter control system adopts a dual closed-loop control including a voltage outer loop and a current inner loop control. The voltage outer loop controls the voltage across the output capacitor, and the current inner loop controls the resonant inductor current. s is the operating frequency, the transfer function diagram is as follows Figure 7 As shown;

[0144] According to the closed-loop control structure diagram:

[0145]

[0146] Among them, f s is the operating frequency, and They represent the full-bridge LLC resonant converter output voltage reference value and resonant inductor current reference value, G v2 represents the transfer function of the voltage loop controller, G i2 represents the transfer function of the current loop controller, k pu2 , k pi2 is the proportional coefficient and integral coefficient of the voltage loop, k iu2 , k ii2 are the proportional coefficient and integral coefficient of the current loop;

[0147] Furthermore, according to the small signal model of the VIENNA rectifier at the front stage of the charging module and the small signal model of the full-bridge LLC resonant converter at the rear stage of the charging module, the overall small signal model of the charging module is established in combination with the control strategies of the front and rear stages of the charging module, such as Figure 8 shown.

[0148] S400: Calculating the output impedance transfer function and the voltage-current transfer function of the front and rear stages through the overall small signal model of the charging module, and obtaining the impedance model of the charging module according to the output impedance transfer function and the voltage-current transfer function of the front and rear stages;

[0149] In the embodiment of the present application, the closed-loop output impedance of the front-stage VIENNA rectifier is:

[0150]

[0151] Among them, G 11 is the open-loop output impedance of the VIENNA rectifier, G 12 is the steady-state duty cycle of the d-axis d To output voltage u dc The transfer function, G 13 is the steady-state duty cycle of the d-axis d To the d-axis steady-state current i d The transfer function, G c is the current loop open-loop transfer function, G svmis the carrier-SVM link transfer function, and the specific expressions of each transfer function are

[0152]

[0153] In the embodiment of the present application, the closed-loop output impedance of the subsequent full-bridge LLC resonant converter is:

[0154]

[0155] Where Z1 is the open-loop output impedance of the full-bridge LLC resonant converter, G uf is the transfer function from frequency to output voltage, G v2 represents the transfer function of the voltage loop controller, G Li is the transfer function from output current to inductor current, G lf is the transfer function from frequency to inductor current, T is the control loop gain, and the specific expressions of each transfer function are:

[0156]

[0157] Furthermore, according to the closed-loop output impedance of the front-stage VIENNA rectifier and the closed-loop output impedance of the rear-stage full-bridge LLC resonant converter, the closed-loop control impedance model of the charging module is obtained as follows:

[0158]

[0159] Among them, G vv is the transfer function from the VIENNA rectifier input voltage to the full-bridge LLC resonant converter output voltage, G ii is the transfer function from the full-bridge LLC resonant converter output current to the VIENNA rectifier input current, Y L is the input admittance of the full-bridge LLC resonant converter, and the specific expressions of each transfer function are:

[0160]

[0161] S500: Building a system simulation model in the platform to verify the impedance model of the charging module;

[0162] In an embodiment of the present application, a simulation model of the charging module is built in the MATLAB / Simulink simulation software, and a theoretically derived Bode plot is obtained based on the simulation parameters. When the charging module is operating stably, a disturbance current is injected and the amplitude and phase information of the disturbance current and the response disturbance voltage at each frequency point are extracted to obtain a simulated measured impedance Bode plot. The theoretically derived Bode plot and the impedance Bode plot obtained by simulation measurement are compared to obtain the result of impedance model verification of the charging module.

[0163] From the above, it can be seen that the present invention first establishes the small signal model of the front-stage VIENNA rectifier and the rear-stage full-bridge LLC resonant converter of the charging module, and then combines the control strategies of the front and rear stages to construct the small signal model of the charging module, and then derives the impedance model of the charging module, which lays the foundation for the subsequent analysis of the stability of the parallel charging module; and verifies the feasibility and correctness of the charging module impedance modeling method of the electric vehicle charging pile proposed in the present invention through simulation.

[0164] The above is a schematic scheme of a charging module impedance modeling method for an electric vehicle charging pile in this embodiment. It should be noted that the technical scheme of the charging module impedance modeling system of the electric vehicle charging pile and the technical scheme of the charging module impedance modeling method of the electric vehicle charging pile mentioned above belong to the same concept. The details not described in detail in the technical scheme of the charging module impedance modeling system of the electric vehicle charging pile in this embodiment can be referred to the description of the technical scheme of the charging module impedance modeling method of the electric vehicle charging pile mentioned above.

[0165] This embodiment also provides a charging module impedance modeling system for an electric vehicle charging pile, including:

[0166] The charging module front-stage modeling unit is used to obtain the DC operating point after converting the AC system into a DC system through abc / dq coordinate transformation, and introduce disturbances on the DC operating point to establish a small signal model of the charging module front-stage VIENNA rectifier;

[0167] The charging module post-stage modeling unit is used to divide the circuit into independent sub-modules based on the equivalent circuit method, and establish a small signal model of the charging module post-stage full-bridge LLC resonant converter after performing small signal analysis on each sub-module;

[0168] The charging module overall modeling unit is used to establish an overall small signal model of the charging module based on the small signal model of the VIENNA rectifier at the front stage of the charging module and the small signal model of the full-bridge LLC resonant converter at the rear stage of the charging module, combined with the control strategies of the front and rear stages of the charging module;

[0169] An impedance model modeling unit is used to calculate the output impedance transfer function and the voltage-current transfer function of the front and rear stages through the overall small signal model of the charging module, and obtain the impedance model of the charging module according to the output impedance transfer function and the voltage-current transfer function of the front and rear stages;

[0170] The simulation verification unit is used to build a system simulation model in the platform to verify the impedance model of the charging module.

[0171] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0172] This embodiment also provides a computing device, which includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a charging module impedance modeling method for an electric vehicle charging pile is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a button, a trackball or a touchpad set on the housing of the computer device, or an external keyboard, touchpad or mouse.

[0173] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method proposed in the above embodiment is implemented.

[0174] The storage medium proposed in this embodiment and the method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0175] Through the above description of the implementation methods, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (RandomAccess Memory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0176] Example 2

[0177] Reference Fig. 9 and Fig.10 Based on the previous embodiment, this embodiment provides an application example of a charging module impedance modeling method and system for an electric vehicle charging pile, in order to verify and illustrate the technical effects adopted in this method.

[0178] A simulation model of the charging module is built in the MATLAB / Simulink simulation software, and the impedance model verification work is carried out on the basis that the system can operate stably. The simulation parameters are shown in Table 1.

[0179] Table 1: Charging module simulation parameters.

[0180]

[0181] In order to verify the correctness of the proposed charging module impedance modeling method and the derived impedance model, it is necessary to measure through simulation experiments. The current perturbation method is used. The measured quantity is the disturbance voltage corresponding to the disturbance current. The ratio of the disturbance voltage to the disturbance current is the impedance of the charging module, such as Fig. 9 As shown, is the injected disturbance current source, and are the disturbance currents flowing into the charging module side and the load side respectively, is the disturbance voltage, and The ratio of is the output impedance of the charging module.

[0182] Based on the simulation parameters in Table 1, the theoretically derived Bode diagram can be obtained in MATLAB. According to the above measurement principle, when the charging module is running stably, the disturbance current is injected and the amplitude and phase information of the disturbance current and the response disturbance voltage at each frequency point are extracted to obtain the impedance Bode diagram of the simulated measurement. The impedance Bode diagram derived theoretically is compared with the impedance Bode diagram obtained by simulation measurement, as shown in Figure 1. Fig.10 As shown in the figure, the lines represent the theoretical Bote diagram obtained in MATLAB based on the system simulation parameters, and "·" represents the Bote diagram obtained by simulation measurement. According to the comparison between the two, it can be seen that the impedance curve obtained by theoretical deduction and the impedance curve obtained by simulation measurement have a good agreement, which verifies the feasibility and correctness of the charging module impedance modeling method of the electric vehicle charging pile proposed in the present invention.

[0183] Therefore, it can be seen from the above that the present invention first establishes the small signal model of the front-stage VIENNA rectifier and the rear-stage full-bridge LLC resonant converter of the charging module, and then combines the control strategies of the front and rear stages to construct the small signal model of the charging module, and then derives the impedance model of the charging module, which lays the foundation for the subsequent analysis of the stability of the parallel charging module; and verifies the feasibility and correctness of the charging module impedance modeling method of the electric vehicle charging pile proposed in the present invention through simulation.

[0184] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0185] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0186] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0187] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1A function specified in one or more boxes.

[0188] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0189] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0190] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A charging module impedance modeling method for an electric vehicle charging pile, characterized in that: include: The AC system is equivalent to a DC system through coordinate transformation to obtain a DC operating point, and a disturbance is introduced at the DC operating point to establish a small signal model of the front-stage VIENNA rectifier of the charging module; Based on the equivalent circuit method, the circuit is divided into independent sub-modules, and a small signal model of the rear-stage full-bridge LLC resonant converter of the charging module is established after performing small signal analysis on the sub-modules; According to the small signal model of the VIENNA rectifier at the front stage of the charging module and the small signal model of the full-bridge LLC resonant converter at the rear stage of the charging module, an overall small signal model of the charging module is established in combination with the control strategies of the front and rear stages of the charging module; The output impedance transfer function and the voltage-current transfer function of the front and rear stages are calculated through the overall small signal model of the charging module, and the impedance model of the charging module is obtained according to the output impedance transfer function and the voltage-current transfer function of the front and rear stages.

2. The charging module impedance modeling method of the electric vehicle charging pile according to claim 1, characterized in that: The small signal model of the front-stage VIENNA rectifier of the charging module is established as follows: According to the topological structure of the VIENNA rectifier in the front stage of the charging module, the circuit loop equation is written as: Among them, u x (x=a,b,c) represents the three-phase AC grid voltage, i x (x=a,b,c) represents the three-phase output current, L represents the AC side boost inductor, R represents the inductor parasitic resistance, U xO (x=a,b,c) represents the voltage of the input terminal relative to the DC midpoint O, U ON It represents the voltage of the DC side midpoint O relative to the neutral point N of the three-phase AC power grid, C represents the DC output side filter capacitor, u C1 and u C2 Represent the voltage of capacitors C1 and C2 respectively, i C1 and i C2 Respectively represent the current flowing through capacitors C1 and C2, s x Indicates the switching state of the xth phase; Define the threshold function sgni x (x=a, b, c) and the rectifier bridge voltage on the AC side, and the circuit loop equation of the front-stage VIENNA rectifier topology of the charging module is linearized by the switching cycle averaging method, which is expressed as: Among them, V o Indicates the effective value of the DC side output voltage of the previous stage VIENNA rectifier, u Nx (x=a,b,c) represents the phase voltage of the power grid, d x (x=a,b,c) represents the duty cycle; The three-phase stationary abc coordinate system is transformed into a two-phase synchronous rotating dq coordinate system through Park transformation. After the dq coordinate system is decoupled, the state equation corresponding to the front-stage VIENNA rectifier of the charging module is: The DC operating point obtained is: Among them, U d ,I d , D d , D q All are steady-state operating points, I s and U s Respectively represent the RMS value of grid-side current and grid voltage, i d 、i q represents the steady-state current in dq coordinates, U dc represents the steady-state output voltage, i dc Represents the steady-state output current, ω o Indicates the operating angular frequency, d d ,d q represents the steady-state duty cycle in dq coordinates; When the front-stage VIENNA rectifier of the charging module operates at unity power factor, the q-axis component is 0. A small disturbance is introduced at the stable operating point of the VIENNA rectifier and linearized. The linear small signal state equation of the VIENNA rectifier is obtained by ignoring the high-order terms: Among them, U dc represents the steady-state output voltage of the VIENNA rectifier, "^" represents the disturbance amount; A small signal model of the front-stage VIENNA rectifier of the charging module is established according to the linear small signal state equation of the VIENNA rectifier.

3. The charging module impedance modeling method of the electric vehicle charging pile according to claim 1, characterized in that: The small signal model of the full-bridge LLC resonant converter at the rear stage of the charging module is established as follows: The small signal model of the switch tube and the secondary rectifier diode of the full-bridge LLC resonant converter is: Among them, u k is the bridge arm output voltage, u dc is the output voltage of the VIENNA rectifier, i.e. the input voltage of the full-bridge LLC resonant converter, is the current flowing through the resonant inductor The real part, i in_LLC is the input current of the full-bridge LLC resonant converter, u R is the transformer primary voltage, R r and R i are the equivalent impedance of the real and imaginary parts of the primary side of the transformer, r is the equivalent impedance, and They are The real and imaginary parts, k r , k i is the coefficient, u o is the output voltage of the full-bridge LLC resonant converter; The small signal model of the resonant inductor of the full-bridge LLC resonant converter is: Among them, L s is the resonant inductance, ω s represents the switching angular frequency, i Ls represents the current flowing through the resonant inductor, u Ls represents the voltage across the resonant inductor, Indicates i Ls The phasor form of The small signal model of the magnetizing inductance of the full-bridge LLC resonant converter is: Among them, L m is the excitation magnetic inductance, i Lm represents the current flowing through the magnetizing inductor, Indicates i Lm The phasor form, u Lm Represents the voltage across the magnetizing inductor; The small signal model of the resonant capacitor of the full-bridge LLC resonant converter is: Among them, C s is the resonant capacitor, i Cs represents the current flowing through the resonant capacitor, u Cs represents the voltage across the resonant capacitor, Indicates u Cs The phasor form of When the switching frequency is much larger than the modulation frequency, the resonant network is simplified to an equivalent inductor in series, and the circuits are merged using the Thevenin and Norton branch equivalent transformation methods, reducing the system model order from the original seventh order to the third order. When the full-bridge LLC resonant converter operates at a frequency slightly lower than the resonant frequency, R s / ω s L m The value of is approximately zero, at this time γ≈1, and the circuit loop equation is written as: Among them, L c is the simplified equivalent inductance, R s is the modulus of the impedance of the resonant inductor and the resonant capacitor.

4. The charging module impedance modeling method of the electric vehicle charging pile according to claim 2 or 3, characterized in that: The overall small signal model of the charging module is established by combining the control strategies of the front and rear stages of the charging module, including: The front-stage VIENNA rectifier adopts dual closed-loop control including voltage outer loop and current inner loop control, wherein the voltage outer loop mainly adopts proportional integral controller, and the current inner loop mainly adopts feedforward decoupling control to eliminate cross coupling between dq axes; According to the closed-loop control structure diagram: in, and They represent the output voltage reference value and d-axis current reference value of the VIENNA rectifier, G v1 represents the transfer function of the voltage loop controller, k pu1 , k pi1 They represent the voltage loop proportional coefficient and integral coefficient respectively, s represents the complex frequency domain variable in Laplace transform, G i1 represents the transfer function of the current loop controller, represents the reference value of the q-axis current, k iu1 , k ii1 They represent the proportional coefficient and integral coefficient of the current loop respectively.

5. The charging module impedance modeling method of the electric vehicle charging pile as claimed in claim 4, characterized in that: The overall small signal model of the charging module is established by combining the control strategies of the front and rear stages of the charging module, and further includes: The full-bridge LLC resonant converter control system adopts dual closed-loop control including voltage outer loop and current inner loop control. The voltage outer loop controls the voltage across the output capacitor, while the current inner loop controls the resonant inductor current. According to the closed-loop control structure diagram: Among them, f s is the operating frequency, and They represent the full-bridge LLC resonant converter output voltage reference value and resonant inductor current reference value, G v2 represents the transfer function of the voltage loop controller, G i2 represents the transfer function of the current loop controller, k pu2 , k pi2 is the proportional coefficient and integral coefficient of the voltage loop, k iu2 , k ii2 are the proportional coefficient and integral coefficient of the current loop; According to the small signal model of the front-stage VIENNA rectifier of the charging module and the small signal model of the rear-stage full-bridge LLC resonant converter of the charging module, an overall small signal model of the charging module is established in combination with the control strategies of the front- and rear-stages of the charging module.

6. The charging module impedance modeling method of the electric vehicle charging pile as claimed in claim 5, characterized in that: The impedance model of the charging module obtained according to the output impedance transfer function and the voltage and current transfer function of the previous and next stages includes: The closed-loop output impedance of the front-stage VIENNA rectifier is: Among them, G 11 is the open-loop output impedance of the VIENNA rectifier, G 12 is the steady-state duty cycle of the d-axis d To output voltage u dc The transfer function, G c is the current loop open-loop transfer function; The closed-loop output impedance of the subsequent full-bridge LLC resonant converter is: Where Z1 is the open-loop output impedance of the full-bridge LLC resonant converter, G uf is the transfer function from frequency to output voltage, G v2 represents the transfer function of the voltage loop controller, G Li is the transfer function from output current to inductor current, G lf is the transfer function from frequency to inductor current, T is the control loop gain; The closed-loop control impedance model of the charging module is obtained according to the closed-loop output impedance of the front-stage VIENNA rectifier and the closed-loop output impedance of the rear-stage full-bridge LLC resonant converter: Among them, G vv is the transfer function from the VIENNA rectifier input voltage to the full-bridge LLC resonant converter output voltage, G ii is the transfer function from the full-bridge LLC resonant converter output current to the VIENNA rectifier input current, Y L is the input admittance of the full-bridge LLC resonant converter.

7. The charging module impedance modeling method of the electric vehicle charging pile according to claim 6, characterized in that: Building a system simulation model in the platform to verify the impedance model of the charging module includes: A simulation model of the charging module is built, and a theoretically derived Bode plot is obtained based on the simulation parameters. When the charging module is operating stably, a disturbance current is injected and the amplitude and phase information of the disturbance current and the response disturbance voltage at each frequency point are extracted to obtain a simulated measured impedance Bode plot. The theoretically derived Bode plot is compared with the impedance Bode plot obtained by simulation measurement to obtain the result of impedance model verification of the charging module.

8. A system using the charging module impedance modeling method of an electric vehicle charging pile as claimed in any one of claims 1 to 7, characterized in that: include: A charging module front-stage modeling unit, used to obtain a DC operating point after converting an AC system into a DC system through coordinate transformation, and introduce a disturbance at the DC operating point to establish a small signal model of a front-stage VIENNA rectifier of the charging module; A charging module post-stage modeling unit, used to divide the circuit into independent sub-modules based on an equivalent circuit method, and establish a small signal model of the charging module post-stage full-bridge LLC resonant converter after performing small signal analysis on each sub-module; The charging module overall modeling unit is used to establish an overall small signal model of the charging module according to the small signal model of the front-stage VIENNA rectifier of the charging module and the small signal model of the rear-stage full-bridge LLC resonant converter of the charging module, combined with the control strategies of the front-stage and rear-stage of the charging module; The impedance model modeling unit is used to calculate the output impedance transfer function and the voltage-current transfer function of the front and rear stages through the overall small signal model of the charging module, and obtain the impedance model of the charging module according to the output impedance transfer function and the voltage-current transfer function of the front and rear stages.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having computer program instructions stored thereon, wherein the computer-executable instructions, when executed by a processor, implement the steps of the method according to any one of claims 1 to 7.

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