Control method and system of single-stage three-port V2G charging device

Abstract

The invention discloses a control method and system for a single-stage three-port V2G charging device, and relates to the technical field of charging pile converters, and the method comprises the steps: constructing a structure of a three-port converter, and obtaining a working mode of the converter; a phase shift control mode is adopted between the ports and between the two bridge arms of the full-bridge circuit; bidirectional power flow of energy between a power grid and a new energy automobile battery is completed, and multifunctional charging and discharging management is achieved. The converter is of a single-stage structure and has high power density, and flexible and bidirectional power exchange between alternating current and direct current ports can be achieved without a two-stage structure. In order to improve the efficiency of the converter, a phase shift angle is calculated by taking power as a constraint condition and taking current stress and soft switching as optimization targets, a three-port converter optimization modulation strategy which is suitable for the topology and takes a wide soft switching range and low current stress into account is designed, and efficient and reliable operation of the converter in three working modes of V2G, G2V and H2L can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of charging pile converters, and in particular to a control method and system for a single-stage three-port V2G charging device. Background Art

[0002] With the severe challenges of global climate change and the continuous increase in energy demand, new energy vehicles are developing rapidly, and their charging systems, as the core units of energy conversion, have received extensive attention. Among them, charging piles with V2G (Vehicle-to-Grid) functions are often installed in commercial areas or residential areas, and their power density, charging flexibility, and charging and discharging efficiency have become important concerns. In order to improve the power density and charging and discharging efficiency of charging piles, many topological structures and corresponding control strategies based on high-frequency switching components have been proposed at home and abroad, represented by CLLC converters and phase-shifted full-bridge converters with high symmetry characteristics. However, these two-port converters cannot simultaneously meet multiple power transmission modes such as V2G, G2V (Grid-to-Vehicle), H2L (High voltage-to-Lowvoltage), and the low integration also limits the improvement of their power density. To solve this problem, some scholars reused the switching devices, passive devices or DC bus of basic topologies such as Boost, Buck, Zeta and their derivative structures to obtain a variety of three-port converters with small and high integration characteristics. However, they do not have electrical isolation between the high and low voltage sides, which is not conducive to the reliability requirements of the charging system; on this basis, isolated three-port topologies with different bridge switching power supplies were proposed, but they generally lack AC ports and cannot be directly applied to AC charging systems; further, some scholars added a rectifier structure to the front stage of the DC / DC three-port converter and proposed a three-port converter with an AC port, which helps to solve the problem of inflexible power transmission between the DC bus, power battery and low-voltage equipment. However, the two-stage structure limits the improvement of its efficiency and power density and increases the cost of the converter. Summary of the invention

[0003] In view of the above-mentioned problems, the present invention is proposed.

[0004] Therefore, the problem to be solved by the present invention is: how to solve the problem that the existing isolated three-port topology structure with different bridge switching power supplies has been proposed, but generally lacks an AC port and cannot be directly applied to the AC charging system, and the two-stage structure of the existing converter limits the improvement of its efficiency and power density, and increases the cost of the converter.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a control method for a single-stage three-port V2G charging device, including: constructing a three-port converter structure to obtain the working mode of the converter; adopting a phase-shift control method between each port and between the two bridge arms of the full-bridge circuit; completing the bidirectional power flow of energy between the power grid and the new energy vehicle battery, and realizing multifunctional charging and discharging management.

[0006] As a preferred solution of the control method of a single-stage three-port V2G charging device described in the present invention, the structure of the three-port converter includes a bidirectional full-bridge circuit composed of MOSFET switching devices, a three-winding high-frequency transformer, a Cf1 filter capacitor and an independent full-bridge circuit composed of MOSFET switching devices; the working modes of the converter include G2V mode, V2G mode and H2L mode.

[0007] As a preferred solution of the control method of a single-stage three-port V2G charging device described in the present invention, the phase shift control method includes adopting a phase shift modulation strategy, there is an internal phase shift angle of the full-bridge circuit and an external phase shift angle between the full-bridge circuits between the grid-side port and the power battery port and the storage battery port, and an extended phase shift EPS modulation mode is adopted.

[0008] As a preferred solution of the control method of a single-stage three-port V2G charging device described in the present invention, the bidirectional power flow includes making the circuit equivalent, obtaining the grid-side port power, calculating the power of the power battery end, reducing the converter switching loss, improving the converter efficiency, and designing a soft switching algorithm.

[0009] As a preferred solution of the control method of a single-stage three-port V2G charging device of the present invention, the circuit is equivalently represented as follows:

[0010]

[0011] Among them, L 12eq , L 23eq , L 13eq are the equivalent inductances from port 1 to port 2, port 2 to port 3, and port 1 to port 3, respectively. L1, L2, and L3 are the power transmission inductances of AC ports 1, 2, and 3, respectively. n 12 is the turns ratio between the AC side and the power battery side, n 13 is the turns ratio between the AC side and the low voltage port, n 23 is the turns ratio of the DC high voltage port to the DC low voltage port; the grid side port power calculation is expressed as:

[0012]

[0013] Among them, P G is the network side port power, vpG 、v sH 、v sL are the bridge arm voltages of port 1, port 2, and port 3, respectively, and f s is the switching frequency, D GH is the external shift phase angle between the grid-side bidirectional full-bridge circuit and the power battery-side full-bridge circuit, D GL is the external shift phase angle between the grid-side bidirectional full-bridge circuit and the low-voltage side full-bridge circuit, D L is the internal phase shift angle between the full-bridge circuits on the low-voltage side; the power at the power battery end is calculated as:

[0014]

[0015] Among them, P H is the power of the power battery, D H is the internal phase shift angle between the full-bridge circuits on the low-voltage side; the low-voltage battery end is expressed as:

[0016]

[0017] Among them, P L It is the power of low voltage battery terminal.

[0018] As a preferred solution of the control method of a single-stage three-port V2G charging device described in the present invention, the soft switching algorithm designed includes a lead tube to implement soft switching, which is expressed as:

[0019]

[0020] The soft switching of the hysteresis tube is expressed as:

[0021]

[0022] The full bridge tube realizes soft switching as follows:

[0023]

[0024] Combined with the power transfer expression, the variable D of the critical soft switching condition is obtained H The constraint equation is expressed as:

[0025]

[0026] Among them, M GH is the ratio of the AC side voltage to the high voltage side bridge voltage, P N,GH is the reference voltage; where P N,GH , voltage ratio M GH It is expressed as:

[0027]

[0028] Improve soft switching margin, D H Take the midpoint of the range and get D GH It is expressed as:

[0029]

[0030] Among them, D GH It is the outward shift phase angle between the grid-side bidirectional full-bridge circuit and the power battery-side full-bridge circuit.

[0031] As a preferred solution of the control method of a single-stage three-port V2G charging device of the present invention, the H2L mode includes charging the low-voltage device from the high-voltage power battery in the H2L mode, with the goal of minimizing the inductor current peak and satisfying the power demand as a constraint condition, and the optimization model is expressed as:

[0032]

[0033] Among them, I L2 is the inductor current on the high-voltage DC side, P HL is the actual power from the power battery to the low-voltage battery, P HL,ref is the given power from the power battery to the low voltage battery, P HL,max is the upper limit of power transmission from the power battery to the storage battery; the optimal solution of each control variable obtained by solving the model is expressed as:

[0034]

[0035] Among them, M HL is the ratio of the bridge arm voltage on the high voltage DC side to the bridge arm voltage on the low voltage DC side, P N,HL is the reference voltage in H2L mode.

[0036] Another object of the present invention is to provide a system of a control method for a single-stage three-port V2G charging device, which can solve the control problem of a single-stage three-port V2G charging device by constructing a control system for the single-stage three-port V2G charging device.

[0037] In order to solve the above technical problems, the present invention provides the following technical solutions: a control system for a single-stage three-port V2G charging device, comprising a construction module, a phase shift control module and a power flow module; the construction module is used to construct the structure of the three-port converter to obtain the working mode of the converter; the phase shift control module is used to adopt a phase shift control method between each port and between the two bridge arms of the full-bridge circuit; the power flow module is used to complete the bidirectional power flow of energy between the power grid and the new energy vehicle battery, and support the high-voltage battery to charge the low-voltage equipment, thereby realizing multi-functional charging and discharging management.

[0038] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the control method of the single-stage three-port V2G charging device as described above are implemented.

[0039] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the control method of a single-stage three-port V2G charging device as described above.

[0040] The beneficial effects of the present invention are as follows: the control method of a single-stage three-port V2G charging device provided by the present invention has a high power density, and can realize flexible and bidirectional power exchange between AC and DC ports without a two-stage structure. On this basis, a three-port converter optimization modulation strategy suitable for this topology is designed, which takes into account a wide soft switching range and low current stress, and realizes efficient and reliable operation of the converter in the three working modes of V2G, G2V, and H2L. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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 labor.

[0042] Figure 1 This is a flow chart of a control method for a single-stage three-port V2G charging device provided in the first embodiment of the present invention.

[0043] Figure 2 This is a diagram of an isolated three-port bidirectional AC / DC converter device for a control method of a single-stage three-port V2G charging device provided in the first embodiment of the present invention.

[0044] Figure 3 A control block diagram of V2G and G2V control modes of a control method for a single-stage three-port V2G charging device provided by the first embodiment of the present invention.

[0045] Figure 4 This is a H2L mode control block diagram of a control method for a single-stage three-port V2G charging device provided in the first embodiment of the present invention.

[0046] Figure 5 This is a structural diagram of a control system of a single-stage three-port V2G charging device provided in accordance with a second embodiment of the present invention.

[0047] Figure 6The key waveform of the switching cycle of the V2G mode of the control method of a single-stage three-port V2G charging device provided by the third embodiment of the present invention.

[0048] Figure 7 The key waveform of the switching cycle of the G2V mode of the control method of a single-stage three-port V2G charging device provided by the third embodiment of the present invention.

[0049] Figure 8 The key waveforms of the switching cycle of the H2L mode of the control method of a single-stage three-port V2G charging device provided by the third embodiment of the present invention are shown. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, 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 accompanying drawings.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Example 1, reference Figure 1 to Figure 4 , which is the first embodiment of the present invention, provides a control method for a single-stage three-port V2G charging device, including: constructing a three-port converter structure to obtain a converter working mode; using a phase-shift control method between each port and between two bridge arms of a full-bridge circuit; completing a bidirectional power flow of energy between a power grid and a new energy vehicle battery, and realizing multifunctional charging and discharging management.

[0053] The present invention proposes a novel three-port bidirectional AC / DC converter suitable for V2G charging piles. The converter has a high power density and can realize flexible and bidirectional power exchange between AC and DC ports without a two-stage structure. On this basis, a three-port converter optimization modulation strategy suitable for this topology is designed, which takes into account a wide soft switching range and low current stress, so as to realize efficient and reliable operation of the converter in the three working modes of V2G, G2V and H2L.

[0054] S1. Construct the structure of a three-port converter and obtain the working mode of the converter.

[0055] The converter structure includes: a bidirectional full-bridge circuit composed of switches Q1-Q8, a three-winding high-frequency transformer, C f1 Filter capacitor. S 1H -S 4H , S 1L -S 4LThe independent full-bridge circuit is composed of switches. Phase shift control is adopted between each port and between the two bridge arms of the full-bridge circuit to complete the bidirectional power flow of energy between the power grid and the new energy vehicle battery, and support the high-voltage battery to charge the low-voltage equipment, realizing flexible and efficient battery charge and discharge management.

[0056] The power transfer inductors L2 and L3 on the winding N2 and N3 sides and the square wave voltage v between the two full-bridge arms sH 、v sL All are converted to the winding N1 side, ignoring the transformer excitation inductance L m , the equivalent power transfer model can be obtained, and the turns ratio n is defined xy =N x / N y , then the equivalent power transfer inductance is (n 12 ) 2 L2、(n 13 ) 2 L3, equivalent port voltage n 12 v sH 、n 13 v sL ,i L1 is the current of inductor L1.

[0057] like Figure 2 As shown in FIG. 1 , an isolated three-port bidirectional AC / DC converter device according to the present invention is shown. The converter has a three-winding high-frequency transformer (the transformer turns ratio is N1:N2:N3), i s is the transformer current, C f1 The transformer high voltage primary winding N1 is connected to the bidirectional full bridge circuit composed of switches Q1-Q8, and the grid-side filter inductor L g With the power grid (voltage is recorded as v ac ) for power exchange. The secondary windings N2 and N3 of the transformer are each connected through an independent full-bridge circuit (S 1H -S 4H , S 1L -S 4L ) and power battery (voltage is recorded as v dcH ) port and low voltage device (voltage is recorded as v dcL ) ports are connected, and phase-shift control is adopted between each port and between the two bridge arms of the full-bridge circuit to complete the two-way power flow of energy between the power grid and the new energy vehicle battery, and support the high-voltage battery to charge the low-voltage equipment, so as to realize flexible and efficient charging and discharging management of the battery.

[0058] The converter's operating modes include G2V mode, V2G mode and H2L mode.

[0059] S2, phase shift control is adopted between each port and between the two bridge arms of the full-bridge circuit.

[0060] The converter adopts a phase-shift modulation strategy, and there is an internal phase shift angle of the full-bridge circuit and an external phase shift angle between the full-bridge circuits between the grid-side port and the power battery port and the storage battery port. Therefore, an extended-phase-shift EPS (extended-phase-shift) modulation mode can be adopted.

[0061] S3. Complete the two-way power flow of energy between the power grid and new energy vehicle batteries, and realize multi-functional charging and discharging management.

[0062] The circuit is equivalent to obtain the grid-side port power, calculate the power of the power battery end, reduce the converter switching loss, improve the converter efficiency, and design a soft switching algorithm.

[0063] Calculate the three square wave voltages v after conversion to the winding N1 side pG 、n 12 v sH 、n 13 v sL The equivalent inductance between the two can be obtained as L 12eq , L 13eq , L 23eq The expression is as follows:

[0064]

[0065] Among them, L 12eq , L 23eq , L 13eq are the equivalent inductances from port 1 (AC side port) to port 2 (DC side high voltage port), port 2 to port 3 (DC side low voltage port), and port 1 to port 3. L1, L2, and L3 are the power transmission inductances of AC ports 1, 2, and 3, respectively. n 12 is the turns ratio between the AC side and the power battery side, n 13 is the turns ratio between the AC side and the low voltage port, n 23 is the turns ratio of the DC high voltage port to the DC low voltage port.

[0066] The converter transmission power is the integral of the product of the average value of the inductor current and the voltage. The power expression of the converter grid-side port can be obtained by calculation, which is expressed as:

[0067]

[0068] Among them, P G is the network side port power, v pG 、v sH 、v sL are the bridge arm voltages of port 1, port 2, and port 3, respectively, and f s is the switching frequency, D GH is the external shift phase angle between the grid-side bidirectional full-bridge circuit and the power battery-side full-bridge circuit, DGL is the external shift phase angle between the grid-side bidirectional full-bridge circuit and the low-voltage side full-bridge circuit, D L is the internal phase shift angle between the full-bridge circuits on the low-voltage side.

[0069] The power expression of the power battery side port is:

[0070]

[0071] Among them, P H is the power of the power battery, D H is the internal phase shift angle between the full-bridge circuits on the low-voltage side.

[0072] The low voltage battery terminal is represented as:

[0073]

[0074] Among them, P L It is the power of low voltage battery terminal.

[0075] like Figure 3 As shown in the figure, it is a control block diagram of V2G and G2V control modes. In the V2G mode, the phase information of the grid voltage is first obtained through the phase-locked loop, where v ac is the grid voltage, θ is the grid phase, V dcH With V dcL They are respectively the high and low voltages on the DC side. Combined with the grid-side current given value amplitude i acmref Get the reference current signal i acref , and the actual current signal i ac The comparison is then completed through the PR controller to close the loop. 12ref With P 13ref For a given power generated, M GL 、M GH are the ratio of the DC side low voltage to the grid voltage, and the ratio of the DC side high voltage to the grid voltage. H and feedforward value D GHf , D GLf Calculated by the proposed algorithm, I dcL with I dcH are high and low voltage battery currents respectively. In G2V mode, the grid side supplies power to both the power battery and the storage battery at the same time. H , D L Remain unchanged, D GL , D GH are opposite to each other, and the converter operation can be regarded as completing the reverse power transmission of two V2Gs independently through two equivalent inductors. In this mode, a double closed-loop strategy is used to control D GH and D GL When the voltage is much smaller than the given voltage V dcH_ref 、VdcL_ref When the voltage loop is saturated, the constant current charging mode is adopted to quickly increase the voltage. When the voltage is close to the given voltage, the constant voltage charging mode is adopted, and the charging current continues to decrease. When it decreases to the threshold, the charging ends.

[0076] In V2G mode, energy is fed back to the grid by the power battery. In order to reduce the switching loss of the converter and improve the efficiency of the converter, the soft switching conditions must be analyzed. 1H , S 2H The conditions for soft switching are:

[0077]

[0078] Hysteresis tube S 1H , S 2H The conditions for soft switching are:

[0079]

[0080] The conditions for realizing the bidirectional full-bridge soft switch are:

[0081]

[0082] Combined with the power transfer expression, the variable D of the critical soft switching condition can be obtained H The constraint equations are as follows:

[0083]

[0084] Among them, M GH is the ratio of the AC side voltage to the high voltage side bridge voltage, P N,GH is the reference voltage;

[0085] Where P N,GH , voltage ratio M GH It is expressed as:

[0086]

[0087] To improve the soft switching margin, D H Taking the midpoint of this range and substituting it into the power transfer expression, we can get D GH The expression is:

[0088]

[0089] Among them, D GH It is the outward shift phase angle between the grid-side bidirectional full-bridge circuit and the power battery-side full-bridge circuit.

[0090] like Figure 4 As shown in the figure, it is the control block diagram of H2L control mode. dcLref Indicates the given current at the low-voltage device side port, idcL Indicates the actual current at the low-voltage device side port. The two are compared and passed through the PI controller. HL is the ratio of the DC side low voltage to the DC side high voltage, P 12ref This mode is the power given value. HL The feedforward value D HLf , and D generated by the phase shift generation module H , D L , the energy transmission from the power battery to the storage battery is completed through the phase-shift controller control circuit.

[0091] In H2L mode, the high voltage power battery charges the low voltage equipment. This control strategy involves D GL , D GH , D HL Three control variables, to be consistent with the above control variables, D GL Set to zero, then D HL Available through D GH Control, with the goal of minimizing the inductor current peak and the constraint of meeting the power demand, the optimization model is as follows:

[0092]

[0093] Among them, I L2 is the inductor current on the high-voltage DC side, P HL is the actual power from the power battery to the low-voltage battery, P HL,ref is the given power from the power battery to the low voltage battery, P HL,max is the upper limit of power transmission from the power battery to the storage battery. Solving the model to obtain the optimal solution of each control variable is as follows:

[0094]

[0095]

[0096] Among them, M HL is the ratio of the bridge arm voltage on the high voltage DC side to the bridge arm voltage on the low voltage DC side, P N,HL is the reference voltage in H2L mode.

[0097] Example 2, reference Figure 5 , which is the second embodiment of the present invention, is different from the previous embodiment in that it provides a control system for a single-stage three-port V2G charging device, including: a construction module 100, a phase shift control module 200 and a power flow module 300.

[0098] The construction module 100 is used to construct the structure of a three-port converter and obtain the working mode of the converter.

[0099] The phase shift control module 200 is used to adopt a phase shift control method between each port and between two bridge arms of a full-bridge circuit.

[0100] The power flow module 300 is used to complete the bidirectional power flow of energy between the power grid and the new energy vehicle battery, and supports the high-voltage battery to charge the low-voltage equipment, realizing multi-functional charging and discharging management.

[0101] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0102] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0103] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0104] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0105] Example 3, reference Figure 6 to Figure 8 , which is the third embodiment of the invention, and which is different from the first two embodiments in that: it is used to verify and illustrate the technical effects adopted in the present invention in order to verify the real effects of this method.

[0106] Figure 6 It is the key waveform of the switching cycle of the V2G mode involved in the present invention. Under the condition of 2000W transmission power, the effective value of the inductor current is about 18A, and all the switch tubes of the converter have achieved ZVS, which verifies the effectiveness of the control strategy.

[0107] Figure 7 It is the key waveform of the switching cycle of the G2V mode involved in the present invention. It can be seen that at this time, the power flows from the grid side to the battery side, the power battery and the storage battery are both in a charging state, and at the same time, each switch of the converter still meets the soft switching conditions, which verifies the effectiveness of its control strategy in the G2V working mode.

[0108] Figure 8 The key waveform of the switching cycle of the H2L mode involved in the present invention. In the H2L mode, the TPS low current stress wide soft switching range modulation strategy is adopted, the current stress is low most of the time, and all switch tubes realize soft switching, which verifies the effectiveness of the optimization algorithm in the H2L mode.

[0109] 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.

Claims

1. A control method for a single-stage three-port V2G charging device, characterized in that: include, Construct the structure of the three-port converter and obtain the converter's operating mode; Phase shift control is adopted between each port and between the two bridge arms of the full-bridge circuit; Complete the two-way power flow of energy between the power grid and new energy vehicle batteries, and realize multi-functional charging and discharging management.

2. The control method of a single-stage three-port V2G charging device according to claim 1, characterized in that: The structure of the three-port converter includes a bidirectional full-bridge circuit composed of MOSFET switching devices, a three-winding high-frequency transformer, a Cf1 filter capacitor and an independent full-bridge circuit composed of MOSFET switching devices; The operation modes of the converter include a G2V mode, a V2G mode and a H2L mode.

3. The control method of a single-stage three-port V2G charging device according to claim 2, characterized in that: The phase shift control method includes adopting a phase shift modulation strategy, with an internal phase shift angle of the full-bridge circuit and an external phase shift angle between the full-bridge circuits between the grid-side port and the power battery port and the storage battery port, and adopting an extended phase shift EPS modulation mode.

4. The control method of a single-stage three-port V2G charging device according to claim 3, characterized in that: The bidirectional power flow includes making the circuit equivalent, obtaining the grid-side port power, calculating the power of the power battery end, reducing the converter switching loss, improving the converter efficiency, and designing a soft switching algorithm.

5. The control method of a single-stage three-port V2G charging device according to claim 4, characterized in that: The circuit is equivalently represented as: Among them, L 12eq , L 23eq , L 13eq are the equivalent inductances from port 1 to port 2, port 2 to port 3, and port 1 to port 3, respectively. L1, L2, and L3 are the power transmission inductances of AC ports 1, 2, and 3, respectively. n 12 is the turns ratio between the AC side and the power battery side, n 13 is the turns ratio between the AC side and the low voltage port, n 23 is the turns ratio of the DC high voltage port to the DC low voltage port; The network side port power calculation is expressed as: Among them, P G is the power of the network side port, v pG 、v sH 、v sL are the bridge arm voltages of port 1, port 2, and port 3, respectively, and f s is the switching frequency, D GH is the external shift phase angle between the grid-side bidirectional full-bridge circuit and the power battery-side full-bridge circuit, D GL is the external shift phase angle between the grid-side bidirectional full-bridge circuit and the low-voltage side full-bridge circuit, D L is the internal phase shift angle between the full-bridge circuits on the low-voltage side; The power of the power battery terminal is calculated as: Among them, P H is the power of the power battery, D H is the internal phase shift angle between the full-bridge circuits on the low-voltage side; The low voltage battery terminal is represented as, Among them, P L It is the power of low voltage battery terminal.

6. The control method of a single-stage three-port V2G charging device according to claim 5, characterized in that: The soft switching algorithm designed includes the advance tube to achieve soft switching, which is expressed as: The soft switching of the hysteresis tube is expressed as: The full bridge tube realizes soft switching as follows: Combined with the power transfer expression, the variable D of the critical soft switching condition is obtained H The constraint equation is expressed as, Among them, M GH is the ratio of the AC side voltage to the high voltage side bridge voltage, P N,GH is the reference voltage; Where P N,GH , voltage ratio M GH It is expressed as, Improve soft switching margin, D H Take the midpoint of the range and get D GH It is expressed as, Among them, D GH It is the outward shift phase angle between the grid-side bidirectional full-bridge circuit and the power battery-side full-bridge circuit.

7. The control method of a single-stage three-port V2G charging device according to claim 6, characterized in that: The H2L mode includes charging the low-voltage device from the high-voltage power battery in the H2L mode, with the goal of minimizing the inductor current peak and satisfying the power demand as a constraint condition. The optimization model is expressed as: Among them, I L2 is the inductor current on the high-voltage DC side, P HL is the actual power from the power battery to the low-voltage battery, P HL,ref is the given power from the power battery to the low voltage battery, P HL,max The upper limit of power transfer from the power battery to the storage battery; Solving the model to obtain the optimal solution of each control variable is expressed as: Among them, M HL is the ratio of the bridge arm voltage on the high voltage DC side to the bridge arm voltage on the low voltage DC side, P N,HL is the reference voltage in H2L mode.

8. A system using a control method of a single-stage three-port V2G charging device as claimed in any one of claims 1 to 7, characterized in that: It includes a construction module (100), a phase shift control module (200) and a power flow module (300); The construction module (100) is used to construct the structure of a three-port converter to obtain the working mode of the converter; The phase shift control module (200) is used to adopt a phase shift control method between each port and between two bridge arms of a full-bridge circuit; The power flow module (300) is used to complete the bidirectional power flow of energy between the power grid and the new energy vehicle battery, and supports the high-voltage battery to charge the low-voltage equipment, thereby realizing multifunctional charging and discharging management.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the control method of a single-stage three-port V2G charging device according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a control method of a single-stage three-port V2G charging device according to any one of claims 1 to 7 are implemented.

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