Swiss rectifier control method and system applied to electric vehicle charger

Abstract

The application discloses a Swiss rectifier control method and system applied to an electric vehicle charger, the modeling precision of the Swiss rectifier is improved, the output current ripple amplitude is reduced, the quality of input and output currents is improved, and therefore the reliability of battery charging is improved by combining passive control and fractional order theory.

Description

Technical Field

[0001] This invention belongs to the technical field of electric vehicle charging control, and particularly relates to a Swiss rectifier control method and system applied to electric vehicle chargers. Background Technology

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

[0003] With the increasing environmental pollution caused by automobiles and the growing oil crisis, the development of electric vehicles is attracting more and more attention. However, driving range remains a significant obstacle to the widespread adoption of electric vehicles. This is not solely determined by battery technology performance; how batteries are used and charged also greatly influence their performance. From this perspective, battery charger technology is crucial to battery performance.

[0004] Common charger topologies such as six-switch buck-type rectifiers, matrix rectifiers, and Vienna rectifiers have a high DC voltage output range, requiring an additional DC / DC converter to step down the voltage before connecting to the load. In contrast, Swiss rectifiers require only a single-stage conversion to output a DC voltage suitable for electric vehicle batteries. Compared to two-stage conversion, single-stage conversion offers higher output efficiency and lower cost.

[0005] In terms of control schemes, rectifiers generally employ PI control, with a faster inner current loop controlling the input current to maintain a sinusoidal shape, and a slower outer voltage loop stabilizing the output voltage. However, due to the limited gain and bandwidth of the PI controller, it cannot effectively suppress the influence of inductor current on the input current. Furthermore, due to the nonlinear characteristics of the switching converter, traditional linear control strategies are difficult to meet high control requirements. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a Swiss rectifier control method and system for electric vehicle chargers.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solution: a Swiss rectifier control method applied to an electric vehicle charger, comprising:

[0008] The Swiss rectifier is converted into a fractional-order equivalent DC / DC model, and the duty cycle control law is obtained based on the fractional-order equivalent DC / DC model.

[0009] Based on the dynamic model of the Swiss rectifier with inductor charge and capacitor charge as generalized coordinates, the Swiss rectifier system EL equation is established. Based on the transformation relationship between the generalized coordinates and the state variables in the Swiss rectifier circuit, the periodic average value of the inductor current is obtained after transforming the Swiss rectifier system EL equation.

[0010] Based on the fractional-order equivalent DC / DC model, the instantaneous equivalent model of the Swiss rectifier is derived. Based on the duty cycle control law, the duty cycle condition function of the Swiss rectifier switch is obtained. The periodic average value of the inductor current is substituted into the duty cycle condition function of the Swiss rectifier switch, thereby controlling the Swiss rectifier.

[0011] Secondly, an embodiment of the present invention provides a Swiss rectifier control system applied to an electric vehicle charger, comprising:

[0012] Fractional-order model conversion module: Converts the Swiss rectifier into a fractional-order equivalent DC / DC model, and obtains the duty cycle control law based on the fractional-order equivalent DC / DC model;

[0013] Dynamics modeling module: Based on the dynamics model of the Swiss rectifier with inductor charge and capacitor charge as generalized coordinates, the EL equation of the Swiss rectifier system is established. Based on the transformation relationship between the generalized coordinates and the state variables in the Swiss rectifier circuit, the EL equation of the Swiss rectifier system is transformed to obtain the periodic average value of the inductor current.

[0014] Control module: Based on the fractional-order equivalent DC / DC model, the instantaneous equivalent model of the Swiss rectifier is derived. Based on the duty cycle control law, the duty cycle condition function of the Swiss rectifier switch is obtained. The periodic average value of the inductor current is substituted into the duty cycle condition function of the Swiss rectifier switch to control the Swiss rectifier.

[0015] Thirdly, embodiments of the present invention provide a computer device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the computer device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, they perform the steps of the Swiss rectifier control method applied to an electric vehicle charger as described above.

[0016] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the Swiss rectifier control method for an electric vehicle charger described above.

[0017] The above one or more technical solutions have the following beneficial effects:

[0018] In this invention, by combining passive control and fractional-order theory, the modeling accuracy of the Swiss rectifier is improved, the amplitude of the output current ripple is reduced, and the quality of the input and output current is improved, thereby improving the reliability of battery charging.

[0019] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is the Swiss rectifier circuit topology in Embodiment 1 of the present invention;

[0022] Figure 2 shows the symbol of the fractional-order reactance element in Embodiment 1 of the present invention;

[0023] Figure 3 This is the Swiss rectifier circuit topology that incorporates fractional reactance in Embodiment 1 of the present invention;

[0024] Figure 4 The first embodiment of this invention is a fractional-order equivalent DC / DC model of a Swiss rectifier;

[0025] Figure 5 This is the instantaneous equivalent model of the Swiss rectifier in Embodiment 1 of the present invention;

[0026] Figure 6(a) shows the Swiss rectifier T in Embodiment 1 of the present invention. p =1,T n When = 1, the switch is in working state;

[0027] Figure 6(b) shows the Swiss rectifier T in Embodiment 1 of the present invention. p =1,T n =0 indicates the switch is in operation.

[0028] Figure 6(c) shows the Swiss rectifier T in Embodiment 1 of the present invention. p =0,T nWhen = 1, the switch is in working state;

[0029] Figure 6(d) shows the Swiss rectifier T in Embodiment 1 of the present invention. p =0,T n =0 indicates the switch is in operation.

[0030] Figure 7 The steady-state voltage and current waveforms of the Swiss rectifier in Embodiment 1 of the present invention are shown below.

[0031] Figure 8 This is a block diagram of the Swiss rectifier based on fractional-order passive control in Embodiment 1 of the present invention;

[0032] Figure 9 The AC side voltage and current waveforms are shown in Embodiment 1 of the present invention;

[0033] Figure 10 This is a comparison of the system power factor under two control schemes in Embodiment 1 of the present invention;

[0034] Figure 11(a) is a diagram of total harmonic distortion of the system under the passive control scheme based on fractional order in Embodiment 1 of the present invention;

[0035] Figure 11(b) is a total harmonic distortion diagram of the PI control scheme system in Embodiment 1 of the present invention;

[0036] Figure 12(a) shows the output voltage waveform under the passive control scheme based on fractional order in Embodiment 1 of the present invention;

[0037] Figure 12(b) is a waveform diagram of the output voltage of the PI control scheme in Embodiment 1 of the present invention;

[0038] Figure 13(a) shows the output current waveform under the passive control scheme based on fractional order in Embodiment 1 of the present invention;

[0039] Figure 13(b) shows the output current waveform under the PI control scheme in Embodiment 1 of the present invention. Detailed Implementation

[0040] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0042] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0043] Example 1

[0044] like Figure 1-Figure 1 As shown in Figure 3, this embodiment discloses a Swiss rectifier control method applied to an electric vehicle charger, including:

[0045] The Swiss rectifier is converted into a fractional-order equivalent DC / DC model, and the duty cycle control law is obtained based on the fractional-order equivalent DC / DC model.

[0046] Based on the dynamic model of the Swiss rectifier with inductor charge and capacitor charge as generalized coordinates, the Swiss rectifier system EL equation is established. Based on the transformation relationship between the generalized coordinates and the state variables in the Swiss rectifier circuit, the periodic average value of the inductor current is obtained after transforming the Swiss rectifier system EL equation.

[0047] Based on the fractional-order equivalent DC / DC model, the instantaneous equivalent model of the Swiss rectifier is derived. Based on the duty cycle control law, the duty cycle condition function of the Swiss rectifier switch is obtained. The periodic average value of the inductor current is substituted into the duty cycle condition function of the Swiss rectifier switch, thereby controlling the Swiss rectifier.

[0048] The Swiss rectifier is a Buck-type rectifier with power factor correction. It features unity power factor operation, low switching losses, adjustable output voltage, and low harmonic pollution. Therefore, the Swiss rectifier is well-suited for use in the circuit topology of electric vehicle battery chargers. Its structure is as follows: Figure 1 As shown.

[0049] However, since capacitors and inductors in actual circuits are components with fractional-order characteristics, different orders affect the actual impedance of the capacitors and inductors, and thus affect their dynamic processes. Therefore, for systems with fractional-order capacitors and inductors, their dynamic characteristics are also affected by the fractional-order characteristics. Therefore, it is necessary to... Figure 1 The capacitors and inductors of the Swiss rectifier are converted into fractional-order reactance components, as shown in Figure 2. The converted fractional-order Swiss circuit is as follows. Figure 3 As shown.

[0050] The Swiss rectifier is considered to be two traditional Buck converters connected in series, so it can also be equivalent to a single-switch Buck converter. Kolar later proposed an equivalent DC / DC model for the Swiss rectifier. Based on this, by incorporating fractional-order reactive components, a fractional-order equivalent DC / DC model was obtained, such as... Figure 4 As shown.

[0051] In this embodiment, taking the fractional-order equivalent DC / DC model as an example, the average value of the input current switching cycle and the average value of the inductor current switching cycle are compared under CCM operating mode. T The relationship is:

[0052] in > T =d T (1)

[0053] If you want the input current in > T Tracking a reference current value I ref ,Right now:

[0054] in > T =I ref (2)

[0055] Combining the above equations, we can obtain the control law equation for the switching duty cycle d of the equivalent DC / DC model:

[0056]

[0057] Among them <> T This represents the average value over a single switching cycle.

[0058] like Figure 5 As shown, the DC / DC equivalent model is inversely derived back to the instantaneous equivalent model of the Swiss rectifier. Specifically, this is achieved using the DC-side inductor current i. Lf Through the switching transistor T p ,T n Control i respectively p i n Tracking the voltage u of the instantaneous maximum and minimum phase voltage pY ,u nY (Y is the neutral point of the power supply) phase, i.e., i p i n Tracking reference current value i p,ref i n,ref ( They are u pY ,u nY (per unit value), i l Peak phase current:

[0059]

[0060] according to Figure 5 From the instantaneous equivalent circuit of the Swiss rectifier, we can see that i p i n The instantaneous value expression is:

[0061]

[0062]

[0063] The above instantaneous value relationship can be expressed in terms of average value as: d p ,d n For the switching transistor T p ,T​​ n Equivalent duty cycle per unit period:

[0064]

[0065] i p i n Tracking Reference i p,ref i n,ref That is, its switching cycle average value is required to track the reference value. Combining equations (4) and (7), we get:

[0066]

[0067] Where Re is the equivalent input resistance of the power supply, substituting equation (3) into equation (8), i.e., the switching transistor T P ,T n To satisfy:

[0068]

[0069] According to equation (9), it is only necessary to obtain the average value of the inductor current over a unit period. This will ultimately yield the duty cycle functions of the two switching transistors.

[0070] In this embodiment, the Swiss rectifier is dynamically modeled. Since classical control theory is only suitable for linear systems and cannot describe the nonlinear characteristics of power electronic systems, passive control is based on the energy balance of the system. In the modeling process, no approximation is made to the nonlinear signals of the system. It is a universal control method that can reflect the essence of nonlinear systems.

[0071] The analogy between electrical systems and mechanical systems is shown in Table 1.

[0072] Table 1: Analogy between Mechanical Systems and Electrical Systems

[0073]

[0074]

[0075] As shown in Figure 6, the four operating states of the two high-frequency switches of the Swiss rectifier are illustrated. If line and component losses are ignored, the inductor charge q in the Swiss rectifier circuit is selected. Lf With capacitor charge q C As the generalized coordinates of the system, that is:

[0076]

[0077] Therefore, the inductor current and capacitor current in the equivalent DC / DC model circuit are:

[0078]

[0079] According to Table 1, the kinetic energy K(i) in the electrical system can be obtained. Lf Potential energy P(q) C ), dissipation function D(i) Lf i C They are respectively:

[0080]

[0081] Based on the definitions of the Lagrangian function and the EL equation for mechanical systems, and drawing an analogy between electrical systems and mechanical systems, we obtain the EL equation for circuits:

[0082]

[0083] In the above equation, F represents the external force received by the circuit, generally referring to the circuit's input voltage. The meaning of the EL equation for the circuit obtained above is: the sum of the voltage or current sources and the induced electromotive force in any loop is equal to the voltage drop across the resistors, inductors, and capacitors in the loop. Therefore, the EL equation is also a generalized representation of Kirchhoff's laws in the circuit. Since the EL equation only relates to the global energy of the system, it can also be used as an analysis method for passive control. In the above equation, λ takes the value 0-1, indicating that the inductor in the loop is actually a fractional-order component, that is, the inductor-induced electromotive force is the fractional derivative of the inductor current.

[0084] The passivity of the Swiss rectifier in Figure 6 is studied based on fractional calculus for each of the four switching states:

[0085] (a) at switch T p On, T n When the circuit is conducting, as shown in Figure 6(a), the kinetic energy, potential energy, and dissipation functions in the circuit are:

[0086]

[0087] At this time, the forces acting on the capacitor and inductor in the circuit are:

[0088] F(q Lf ,q C )=[u pY +u Yn ,0] (15)

[0089] At this point, the Lagrange function of the circuit is:

[0090]

[0091] Therefore, we can conclude that:

[0092]

[0093] In the above equation, α is a real number between 0 and 1, representing that the inductor voltage is the fractional derivative of the inductor current. The EL equation then becomes:

[0094]

[0095] in, For Caputo differential operators, d represents fractional differential operations. α / dt α .

[0096] (b) When switch Tp is on and Tn is off, the kinetic energy, potential energy, and dissipation function (i.e., the Lagrange function) in the circuit are the same as in (a). Therefore, according to equation (14), the forces acting on the inductor and capacitor in the circuit are as follows:

[0097] F(q Lf ,q C )=[u pY ,0] (19)

[0098] According to equation (17), the EL equation for this stage of the circuit is:

[0099]

[0100] (c) When switch Tp is closed and Tn is open, the kinetic energy, potential energy, dissipation function, and Lagrangian function in the circuit are equivalent to (a). The forces acting on the inductor and current at this time are:

[0101] F(q Lf ,q C )=[u Yn ,0] (21)

[0102] Similarly, the EL equation at this time is:

[0103]

[0104] (d) When switch Tp is closed and Tn is closed, the kinetic energy, potential energy, dissipation function, and Lagrangian function in the circuit are equivalent to (a). The forces acting on the inductor and current are:

[0105] F(q Lf ,q C = [0,0] (23)

[0106] The EL equation for the circuit at this point is:

[0107]

[0108] Combining equations (18), (20), (22), and (24), we get:

[0109]

[0110] Formula (25) is for the SWISS rectifier with [q Lf ,q C The dynamic model is based on generalized coordinates. Since passive control establishes the system's EL equations from a global energy perspective, it better reflects the system's dynamic characteristics. However, in typical circuits, inductor current and capacitor voltage are generally used as the state variables of the Swiss rectifier system. The relationship between generalized coordinates and capacitor voltage and current is as follows:

[0111]

[0112] In the above formula, β takes values ​​from 0 to 1, which means that capacitors in actual circuits are fractional-order components, just like inductors. That is, the capacitor current is the fractional derivative of its voltage.

[0113] Substituting formula (26) into formula (25), we get:

[0114]

[0115] Therefore, in continuous conduction mode (CCM), the inductor current and capacitor voltage are chosen as the new state variables of the system, i.e., x1 = i Lf and x2=u C Equation (27) is rearranged as follows:

[0116]

[0117] In order to obtain U S Assume the three-phase input is symmetrical and the power factor is 1, that is:

[0118]

[0119] In the above formula, u l i l d represents the peak values ​​of the input phase voltage and phase current, respectively, in formula (7). p ,d n like Figure 7 As shown, its duty cycle function should satisfy:

[0120]

[0121] When the circuit is in the first sector, u at this time pY ,u Yn according to Figure 7 We can obtain:

[0122]

[0123] Substituting equations (30) and (31) into equation (28), we get:

[0124]

[0125] In the above formula, u l ,u ll i represents the peak values ​​of the phase voltage and line voltage of the input power supply, respectively. l ,I dc These represent the peak phase current and the output DC current, respectively.

[0126] Assuming that the inductance and capacitance have the same order, i.e., α = β, substituting equation (32) into equation (28) and expressing equation (28) in matrix form, we get:

[0127]

[0128]

[0129] Let the desired state variable be The state vector error is e = xx * Then the state error equation can be obtained as follows:

[0130]

[0131] Take the error energy storage function To accelerate H e (x) converges quickly to 0. The fractional-order passive controller design adopts energy shaping and damping injection methods, adding a damping dissipation term R to both sides of the error dynamic equation above. a e, R a for:

[0132]

[0133] When taking a fractional-order passive controller, we can obtain:

[0134]

[0135]

[0136] Find H e (x) is the fractional derivative of time.

[0137]

[0138] Because of the theorem in fractional differentials:

[0139]

[0140] Therefore, the above equation applies to H. e The fractional derivative of (x) with respect to time can be further expressed as:

[0141]

[0142] Therefore, this fractional-order system is strictly passive, and the aforementioned fractional-order passive controller can achieve the control objective.

[0143] Expanding equation (36) gives:

[0144]

[0145] According to the first formula of equation (41), the duty cycle function of the fractional-order equivalent DC / DC model is obtained as follows:

[0146]

[0147] Substituting the duty cycle function into equation (3) above, we obtain the periodic average value of the inductor current:

[0148]

[0149] In the above formula, u PI This means that the output voltage is passed through a PI controller to obtain I. ref Then substitute equation (43) into equation (9) to obtain i p i n Reference value i p,ref i n,ref Thus, T is obtained. p ,T n Duty cycle:

[0150]

[0151] Substituting equation (44) into the instantaneous response model of the Swiss rectifier, we obtain the system control block diagram, as follows: Figure 8 As shown. Equation (44) is actually obtained by combining equations (42), (43), and (9), that is, firstly, the duty cycle d of the equivalent DC / DC model based on the passive theory is obtained through equation (42). Figure 8 The FPBC module in the middle, and then substitute the obtained d into equation (43), u in equation (43) PI It is the output voltage U o The difference between the voltage and the expected voltage is processed by the PI module, and finally the result obtained from equation (43) is... Substituting into equation (9), we obtain equation (44), where They are u pY ,u nY The per-unit value, i.e., u pY ,u nY Divide by the phase voltage of the input power supply The final duty cycle function d p d n The PWM module generates its own high-frequency switching drive PWM signal.

[0152] The fractional-order passive control and the traditional PI control scheme were simulated and verified in terms of output current ripple, THD and output voltage waveform. The main circuit parameters are shown in Table 2.

[0153] Table 2: Main System Parameters

[0154]

[0155]

[0156] like Figure 9 and Figure 10 As shown, the AC current waveforms of both control schemes begin to operate in phase with the AC voltage after approximately 0.1 seconds, with power factors both above 0.99. Furthermore, the power factor of the fractional-order passive control exhibits a significantly smaller fluctuation range compared to the PI control. After adding system load at 0.15 seconds, the output remains stable with no significant change in power factor.

[0157] As shown in Figure 11, the THD of the system under the PI control scheme is 4.68%, while that under the fractional-order passive control scheme is 3.55%, indicating that the fractional-order passive control system has less negative feedback to the power grid. Figure 12 shows that the output voltage of both control schemes stabilizes at the set value. After doubling the load after 0.15 seconds, the output voltage fluctuation range is very small, with the fractional-order passive control scheme showing a faster voltage recovery time. Finally, Figure 13 shows that the output current fluctuation range under the fractional-order passive control scheme is significantly smaller than that under PI control, resulting in a smoother battery charging current and contributing to a safer and more stable charging process.

[0158] Example 2

[0159] This embodiment discloses a Swiss rectifier control system applied to an electric vehicle charger, comprising:

[0160] Fractional-order model conversion module: Converts the Swiss rectifier into a fractional-order equivalent DC / DC model, and obtains the duty cycle control law based on the fractional-order equivalent DC / DC model;

[0161] Dynamics modeling module: Based on the dynamics model of the Swiss rectifier with inductor charge and capacitor charge as generalized coordinates, the EL equation of the Swiss rectifier system is established. Based on the transformation relationship between the generalized coordinates and the state variables in the Swiss rectifier circuit, the EL equation of the Swiss rectifier system is transformed to obtain the periodic average value of the inductor current.

[0162] Control module: Based on the fractional-order equivalent DC / DC model, the instantaneous equivalent model of the Swiss rectifier is derived. Based on the duty cycle control law, the duty cycle condition function of the Swiss rectifier switch is obtained. The periodic average value of the inductor current is substituted into the duty cycle condition function of the Swiss rectifier switch to control the Swiss rectifier.

[0163] Example 3

[0164] The purpose of this embodiment is to provide a computing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method.

[0165] Example 4

[0166] The purpose of this embodiment is to provide a computer-readable storage medium.

[0167] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the above method.

[0168] The steps and methods involved in the apparatuses of Embodiments 2, 3, and 4 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0169] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0170] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention. ​

Claims

1. A Swiss rectifier control method applied to electric vehicle chargers, characterized in that, include: The Swiss rectifier is converted into a fractional-order equivalent DC / DC model, and the duty cycle control law is obtained based on the fractional-order equivalent DC / DC model. Based on the dynamic model of the Swiss rectifier with inductor charge and capacitor charge as generalized coordinates, the Swiss rectifier system EL equation is established. Based on the transformation relationship between the generalized coordinates and the state variables in the Swiss rectifier circuit, the periodic average value of the inductor current is obtained after transforming the Swiss rectifier system EL equation. The transformation relationship between the generalized coordinates and the state variables in the Swiss rectifier circuit is as follows: Where β takes values ​​from 0 to 1, meaning that the capacitor current is the fractional derivative of its voltage; The capacitor charge in the Swiss rectifier circuit; In continuous conduction mode, if inductor current and capacitor voltage are selected as the new state variables of the system, the transformed EL equation is: in, For the Caputo differential operator, These are the voltages of the phases with the maximum and minimum instantaneous voltages, respectively. , ; Based on the fractional-order equivalent DC / DC model, the instantaneous equivalent model of the Swiss rectifier is derived. Based on the duty cycle control law, the duty cycle condition function of the Swiss rectifier switch is obtained. The periodic average value of the inductor current is substituted into the duty cycle condition function of the Swiss rectifier switch, thereby controlling the Swiss rectifier.

2. The Swiss rectifier control method for electric vehicle chargers as described in claim 1, characterized in that, In the fractional-order equivalent DC / DC model, under continuous conduction mode, the duty cycle control law is obtained based on the relationship between the average value of the input current switching cycle and the average value of the inductor current switching cycle.

3. The Swiss rectifier control method for electric vehicle chargers as described in claim 1 establishes the EL equation in the dynamic model using the inductor charge and capacitor charge of the Swiss rectifier as generalized coordinates. Specifically, based on the four switching states of the Swiss rectifier (switch Tp on, Tn on, switch Tp on, Tn off, switch Tp off, Tn on, and switch Tp off, Tn off), the EL equations for different switching states are obtained according to the kinetic energy, potential energy, dissipation function, Lagrange function, and the force relationship between the inductor and capacitor in the circuit under different switching states. The EL equations for different switching states are then combined to obtain the EL equation in the dynamic model.

4. The Swiss rectifier control method for electric vehicle chargers as described in claim 1, wherein the formula for the periodic average value of the inductor current is: in, This means that the output voltage is obtained by passing it through a PI controller. d represents the duty cycle.

5. The Swiss rectifier control method for electric vehicle chargers as described in claim 4, characterized in that, Based on the periodic average value of the inductor current and the control law for the duty cycle obtained from the fractional-order equivalent DC / DC model, the instantaneous equivalent model of the Swiss rectifier is derived by back-reaming, resulting in the Swiss rectifier switching function, which is as follows: 。 6. A Swiss rectifier control system for electric vehicle chargers, characterized in that, The Swiss rectifier control method for an electric vehicle charger, as described in any one of claims 1 to 5, includes: Fractional-order model conversion module: Converts the Swiss rectifier into a fractional-order equivalent DC / DC model, and obtains the duty cycle control law based on the fractional-order equivalent DC / DC model; Dynamics Modeling Module: Based on the dynamics model of the Swiss rectifier with inductor charge and capacitor charge as generalized coordinates, the EL equation of the Swiss rectifier system is established. Based on the transformation relationship between the generalized coordinates and the state variables in the Swiss rectifier circuit, the EL equation of the Swiss rectifier system is transformed to obtain the periodic average value of the inductor current. Control module: Based on the fractional-order equivalent DC / DC model, the instantaneous equivalent model of the Swiss rectifier is derived. Based on the duty cycle control law, the duty cycle condition function of the Swiss rectifier switch is obtained. The periodic average value of the inductor current is substituted into the duty cycle condition function of the Swiss rectifier switch to control the Swiss rectifier.

7. A computer device, characterized in that, include: The system includes a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the computer device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, they perform the steps of a Swiss rectifier control method for an electric vehicle charger as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of a Swiss rectifier control method for an electric vehicle charger as described in any one of claims 1 to 5.

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