Three-active-bridge converter decoupling control method, three-active-bridge converter and photovoltaic system

Abstract

The invention provides a three-active-bridge converter decoupling control method, a three-active-bridge converter and a photovoltaic system. A first port, a second port and a third port of the three-active-bridge converter are coupled through a transformer, the first port, the second port and the third port are each provided with a resonant cavity, each resonant cavity comprises a switch control resonant capacitor and a resonant inductor, the capacitance value of the third port is adjusted, and the capacitance value of the third port is adjusted. And the resonant frequency of the third port is the working frequency of the three-active bridge converter, so that power decoupling between the first port and the second port is realized. By adjusting the number of the switched capacitor branches of different ports, the resonant frequency of the resonant cavity circuit of each port and the transmission power between the ports can be adjusted, and a greater degree of freedom is provided for power adjustment between the ports.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a decoupling control method for a three-active-bridge converter, a three-active-bridge converter and a photovoltaic system. Background Art

[0002] With the rapid development of technologies such as photovoltaic power generation, wind power generation, energy storage batteries and DC microgrids, multi-port converters have attracted more and more attention. Among the multi-port DC transformer topologies, the Three Active Bridge (TAB) converter has high research value and application potential due to its advantages of electrical isolation, wide voltage range and flexible and controllable flow direction. In addition, TAB can also realize single-stage energy exchange between three ports, with higher power density and efficiency. Using TAB to realize the interconnection of energy storage units, new energy power generation units and microgrids has become a research hotspot today.

[0003] However, due to the power coupling between ports, it is difficult to directly control the transmission power between ports. In order to solve the power coupling problem of TAB converter, software decoupling or hardware decoupling methods are often used. Software decoupling is to decouple the energy control between ports by adding a decoupling network to the control system. However, the software decoupling method of TAB converter increases the complexity of control and is not conducive to the stability of the system. Hardware decoupling is mainly divided into inductive type and resonant type, and decoupling is achieved by setting an inductive circuit or a resonant circuit in the TAB converter. However, due to the existence of transformer leakage inductance, the inductive TAB converter cannot truly achieve topological level decoupling. Moreover, due to the current characteristics of the inductive TAB converter, the current stress of the switch tube is large, thereby reducing the efficiency of the system. In contrast, the current stress of the resonant decoupled TAB converter is small, and one of the resonant cavities in its circuit topology usually resonates at the same frequency as the switching frequency, and the frequencies of the other two resonant cavities are slightly lower than the switching frequency. However, the resonant frequency of the decoupling resonant cavity must be consistent with the switching frequency to achieve resonant power decoupling, which puts forward certain requirements for the resonant cavity design of the TAB converter and reduces the adaptability of the system. Summary of the invention

[0004] Technical Problems to be Solved by the Invention

[0005] In view of the above situation, the purpose of the present invention is to overcome the shortcomings of the existing TAB converter power decoupling technology and provide a TAB converter decoupling control method with adjustable resonant capacitance, a TAB converter and a photovoltaic system. By adjusting the resonant capacitance values ​​of the three ports of the TAB converter, resonant hardware power decoupling is achieved, without the need for complex software decoupling strategies or the addition of additional inductors, and the transmission power between each port can be adjusted, thereby improving the efficiency and stability of power transmission and enhancing the overall performance and reliability of the system.

[0006] Technical means for solving technical problems

[0007] To solve the above technical problems, according to some exemplary embodiments of the present disclosure, a decoupling control method for a three-active bridge converter is provided, wherein the first port, the second port and the third port of the three-active bridge converter are coupled via a transformer, the first port, the second port and the third port all have a resonant cavity, and the resonant cavity includes a switch-controlled resonant capacitor and a resonant inductor with adjustable capacitance value, and by adjusting the capacitance value of the third port, the resonant frequency of the third port is made to be the operating frequency of the three-active bridge converter, thereby achieving power decoupling between the first port and the second port.

[0008] In some embodiments, the switch-controlled resonant capacitor includes: a plurality of resonant capacitors connected in parallel; and a switch tube connected to each of the resonant capacitors. In the third port, the number of the resonant capacitors connected in parallel in the switch-controlled resonant capacitor is changed by controlling the on and off of the switch tube, thereby adjusting the resonant frequency of the third port.

[0009] In some embodiments, the capacitance value of the first port or the second port is adjusted by controlling the on / off of the switch tube in the first port or the second port so that the resonant frequency of the first port or the second port is a preset specified frequency.

[0010] In some embodiments, the switch tube is composed of two source-source connected MOSFET tubes.

[0011] In some embodiments, the plurality of resonant capacitors connected in parallel in each port have the same capacitance value.

[0012] In some embodiments, the inductance value of the resonant inductor is fixed.

[0013] In some embodiments, when the first port and the second port are decoupled, the resonant frequency of the resonant cavity of the third port satisfies:

[0014]

[0015] Among them, f s : The operating frequency of the three active bridge converters;

[0016] f r3 : The resonant frequency of the resonant cavity of the third port

[0017] L r3 : the inductance value of the resonant inductor of the third port;

[0018] C r3 : the capacitance value of the resonant capacitor of the third port;

[0019] N3: the number of the resonant capacitors connected in parallel through the switch tube in the switch-controlled resonant capacitor of the third port.

[0020] In some embodiments, after the power decoupling, the transmission power of the first port is controlled by the phase angle between the input voltage of the first port and the third port, and the transmission power of the second port is controlled by the phase angle between the input voltage of the second port and the third port.

[0021] In some embodiments, closed-loop power control is performed on the transmission power of the first port and the transmission power of the second port, with a specified reference power as input and actual output power of each of the first port and the second port as output.

[0022] In some embodiments, the first port and the second port are located on the primary side of the transformer, and the third port is located on the secondary side of the transformer.

[0023] According to some exemplary embodiments of the present disclosure, there is also provided a three-active bridge converter, comprising a first port, a second port and a third port coupled via a transformer, wherein the first port, the second port and the third port all have a resonant cavity, and the resonant cavity comprises a switch-controlled resonant capacitor and a resonant inductor with adjustable capacitance value, and when power decoupling is performed on the first port and the second port, the capacitance value of the third port is adjusted so that the resonant frequency of the third port is the operating frequency of the three-active bridge converter.

[0024] According to some exemplary embodiments of the present disclosure, a photovoltaic system is further provided, comprising the triple active bridge converter as described above.

[0025] Effects of the Invention

[0026] According to the TAB converter decoupling control method of the present invention, the power decoupling process can be simplified, and the topological level power decoupling can be achieved by adjusting the resonant capacitor value in the TAB converter, thereby avoiding complex software decoupling strategies and additional inductor components. The method realizes power decoupling by adjusting the resonant capacitor of each port at a constant frequency, and at the same time changes the frequency of the resonant cavity and the transmission power between ports by adjusting the number of parallel branches of the resonant capacitor, thereby providing greater adjustment freedom to adapt to different application requirements. By controlling the switching state of the switch tube in the resonant cavity of each port, the resonant capacitor of each port can be accurately adjusted, so that the resonant cavity of each port can operate at the required frequency, thereby improving the efficiency and stability of power transmission. In addition, the present invention is applicable to photovoltaic energy storage systems, which can better adapt to the changing power requirements in photovoltaic power generation and energy storage systems, and improve the overall performance and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0028] Figure 1 4 is a circuit topology diagram of a TAB converter according to an embodiment of the present invention.

[0029] Figure 2A 4 is a Y-type equivalent circuit diagram of a TAB converter according to an embodiment of the present invention.

[0030] Figure 2B This is a Δ-type equivalent circuit diagram of a TAB converter according to an embodiment of the present invention.

[0031] Figure 3A It is a schematic block diagram of a TAB converter before power decoupling according to an embodiment of the present invention.

[0032] Figure 3B It is a schematic block diagram of a TAB converter after power decoupling according to an embodiment of the present invention.

[0033] Figure 4 It is a schematic diagram of the power flow direction of the TAB converter power decoupling according to the embodiment of the present invention. DETAILED DESCRIPTION

[0034] The specific implementation methods of the present disclosure will be described below. It should be noted that in the specific description of these implementation methods, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual implementation methods. It should be understood that in the actual implementation of any implementation method, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one implementation method to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present disclosure, some changes in design, manufacturing or production based on the technical content disclosed in the present disclosure are just conventional technical means, and should not be understood as insufficient content of the present disclosure.

[0035] Unless otherwise defined, the technical or scientific terms used in the claims and the specification shall have the usual meanings understood by persons with ordinary skills in the technical field to which the present disclosure belongs. The words "first", "second" and similar words used in the patent application specification and the claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "one" or "one" do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalent elements, and do not exclude other elements or objects. Words such as "connect", "couple" or "connected" and similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0036] In the present disclosure, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution. In the present disclosure, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0037] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0038] The following describes in detail a decoupling control method for a three-active-bridge converter provided according to an embodiment of the present disclosure in conjunction with the accompanying drawings.

[0039] Figure 1 The circuit topology diagram of the TAB three-port converter of the embodiment of the present invention is shown. In the circuit of the TAB converter, the three ports, port 1, port 2, and port 3, are coupled via a three-winding high-frequency transformer T, and the turns ratios of the ports are n1, n2, and n3, respectively. In this embodiment, the side where port 1 and port 2 are located is defined as the primary side of the transformer T, and the side where port 3 is located is defined as the secondary side of the transformer T.

[0040] Port 1 includes a DC power supply U1, an H-bridge converter consisting of switch tubes Q1 to Q4 connected in reverse parallel with diodes, and a resonant cavity connected between the H-bridge converter and the inductor L1 of the transformer T. The resonant cavity is controlled by a switch to control the resonant capacitor SCC1 and the resonant inductor L r1 The switch-controlled resonant capacitor SCC1 includes N resonant capacitors C r1 and 2N MOSFET tubes S as switch tubes 1a ~S N1a and S 1b ~S N1b Each resonant capacitor C r1 MOSFET tube S connected to source-source 1a , S 1b (……S N1a , S N1b ) are connected in series to form a branch, and N such branches are connected in parallel to form a switch-controlled resonant capacitor SCC1.

[0041] Ports 2 and 3 also have the same structure. Port 2 includes a DC power supply U2, an H-bridge converter composed of switch tubes Q5 to Q8, and a resonant capacitor SCC2 and a resonant inductor L controlled by switches. r2 The switch-controlled resonant capacitor SCC2 also includes N resonant capacitors C r2 and 2 MOSFET tubes S 2a , S 2b (……S N2a , S N2b ) to form a parallel branch.

[0042] Port 3 includes a DC power supply U3, a switch tube Q9~Q 12 The H-bridge converter is composed of a switch controlling the resonant capacitor SCC3 and the resonant inductor L r3 The switch-controlled resonant capacitor SCC3 also includes N resonant capacitors C r3 and 2N MOSFET tubes S as switch tubes 3a ~S N3a and S 3b ~S N3bEach resonant capacitor C r3 MOSFET tube S connected to source-source 3a , S 3b (……

[0043] S N3a , S N3b ) are connected in series to form a branch, and N such branches are connected in parallel to form a switch-controlled resonant capacitor SCC3.

[0044] here, Figure 1 The switch-controlled resonant capacitors SCC1, SCC2, and SCC3 of the three ports of the TAB converter shown in the figure all have N parallel resonant capacitor branches, but this is only an example and is not limited to this. The number of parallel branches in the resonant cavity of each port may also be different.

[0045] according to Figure 1 As shown, the MOSFET tube S in each parallel branch of the resonant capacitors SCC1, SCC2, and SCC3 is controlled by the control switch. 1a ~S N1a and S 1b ~S N1b , S 2a ~S N2a and S 2b ~S N2b , S 3a ~S N3a and S 3b ~S N3b The on and off of the three ports can change the resonant capacitor C connected in parallel r1 , C r2 , C r3 The number of ports can be changed to change the resonant capacitance value of each port.

[0046] like Figure 1 As shown, the capacitance values ​​of the switch-controlled resonant capacitors SCC1, SCC2, and SCC3 of each port are respectively:

[0047] C SCC1 =N1C r1 ,C SCC2 =N2C r2 ,C SCC3 =N3C r3 (1)

[0048] Among them, N1, N2 and N3 represent the resonant capacitors C of each port connected by the MOSFET tube. r1 , C r2 , C r3 The number of .

[0049] right Figure 1The circuit structure of the TAB converter shown in the figure can be simplified to obtain Figure 2A The Y-type equivalent circuit diagram is shown in the figure. The equivalent reactances Z1, Z2 and Z3 of the three ports can be expressed as:

[0050]

[0051] Therefore, the resonant frequency of each port of the resonant cavity is r1 、f r2 and f r3 It can be expressed as:

[0052]

[0053] In addition, in order to analyze the power transfer between each port, through Y-△ transformation, we can get Figure 2B The △-shaped equivalent circuit shown in the figure. At this time, the TAB converter can be analyzed as three independent DAB (Dual Active Bridge) converters. The equivalent reactance Z between port 1 and port 2 is 12 , the equivalent reactance Z between port 1 and port 3 13 , the equivalent reactance Z between port 2 and port 3 23 It can be expressed as follows:

[0054]

[0055] based on Figure 2B The Δ model shown in the figure performs fundamental wave analysis, and the fundamental components v of the three-port input voltages v1, v2 and v3 are 1p , v 2p and v 3p Respectively expressed as:

[0056]

[0057] in, represents the phase angle between the centers of the voltages v1 and v2 at ports 1 and 2, represents the phase angle between the centers of the voltages v1 and v3 at ports 1 and 3, α1, α2, and α3 represent the internal phase shift angles of ports 1, 2, and 3, and ω = 2πf s , f s represents the operating frequency of the TAB converter, and U1, U2, and U3 represent the voltages of the DC power supplies of ports 1, 2, and 3 respectively.

[0058] From the turns ratios n1, n2, and n3, we can get the voltage gains of ports 2 and 3 relative to port 1:

[0059]

[0060] The equivalent fundamental current from port 1 to port 2 can be expressed as:

[0061]

[0062] Based on this, the transmission power P between ports 1 and 2 can be calculated 12 for:

[0063]

[0064] Similarly, the transmission power P between ports 1 and 3 can be obtained 13 The transmission power P between ports 2 and 3 23 as follows:

[0065]

[0066] Take the case where the power source transmits power from port 1 and port 2 to port 3 as an example, that is, the TAB converter is a dual-input single-output operating condition. Figure 2B As shown in the figure, although the TAB converter is equivalent to three independent DAB converters, due to the equivalent reactance Z between port 1 and port 2 12 In the presence of , power will be coupled between port 1 and port 2.

[0067] In order to offset the power coupling component between ports, the embodiment of the present invention adopts a hardware power decoupling control method, which specifically adjusts the resonant frequency of each port resonant cavity by changing the number of parallel resonant capacitors (adjusting the values ​​of N1, N2 and N3 in formula (1)), thereby realizing topological level power decoupling of the circuit at a constant frequency, and ultimately enabling each power output of the system to be adjusted by a separate control loop.

[0068] Figure 3A It is a schematic block diagram of a TAB converter before power decoupling according to an embodiment of the present invention, that is, a control strategy block diagram of traditional power decoupling. Figure 3B 1 is a schematic block diagram of a TAB converter after power decoupling according to an embodiment of the present invention. Here, the decoupling between port 1 and port 2 is taken as an example.

[0069] Figure 3A In the traditional power decoupling, the basic principle is to use a given power reference value P 1_ref , P 2_ref Through closed-loop power control, ports 1 and 2 of the TAB converter output the required power P1 and P2 respectively. At the same time, in the closed-loop power control, a mutually coupled phase shift control variable H is introduced to achieve power decoupling. 11 , H 22 Represents the phase shift control variables of ports 1 and 2, which are independent of each other and are responsible for their own port control. 12 , H 21It represents the power coupling relationship (coupling component) between ports 1 and 2, where H 12 Represents the phase angle between the center of the voltage v3 and v1 at port 3 and port 1 The impact on the actual output power P2 of port 2, H 21 Represents the phase angle between the center of voltage v3 and v2 at port 3 and port 2 Impact on the actual output power P1 of port 1.

[0070] According to equations (8) and (9), the output power of port 1 and port 2 under traditional power decoupling can be expressed as:

[0071]

[0072] At this time H 12 and H 21 Both are not 0, indicating that there is a coupling relationship between ports 1 and 2:

[0073]

[0074] To achieve power decoupling between port 1 and port 2, it is necessary to eliminate H 12 , H 21 These two coupling components enable each output of the system to be regulated by a separate control loop. Traditional decoupling methods include software decoupling and hardware decoupling. The software decoupling method that adds a decoupling network to the control system increases the complexity of control and is not conducive to the stability of the system. The inductive hardware decoupling method cannot truly achieve topological level decoupling. It not only requires additional inductance, but also reduces the efficiency of the system. Although the resonant hardware decoupling method can reduce circuit stress, it requires that the resonant frequency of the resonant cavity of one of the ports be strictly consistent with the operating frequency of the TAB converter, which limits the adaptability of the system and cannot meet different application requirements.

[0075] According to the power decoupling control method of the embodiment of the present invention, the number of resonant capacitors connected in parallel to each port is adjustable, so that the resonant frequency of each port can also be adjusted, thereby realizing topological level power decoupling, avoiding complex software decoupling strategies and additional inductor components, and simplifying the implementation process of power decoupling.

[0076] The specific process is as follows.

[0077] according to Figure 2B The Δ model, when the resonant frequency of port 3 is f r3 Equal to the operating frequency f of the TAB converter s When Z3=0, Z 12 =∞,P 12 = 0. At this time, the output power of port 1 and port 2 can be expressed as:

[0078]

[0079] The output power of port 3 is:

[0080]

[0081] The power of the three ports satisfies the following formula:

[0082] P3=P1+P2 (17)

[0083] At this time, the power coupling relationship between ports 1 and 2 is H 12 and H 21 for:

[0084]

[0085] Therefore, the coupling relationship between ports 1 and 2 is released.

[0086] according to Figure 1 The circuit topology of the TAB converter shown in the figure is combined with the above equations (1) and (3). By adjusting the resonant capacitor C connected in parallel in port 3, r3 The number of N3 makes the resonant frequency of port 3 f r3 is the operating frequency f of the TAB converter s ,Right now:

[0087]

[0088] The power P1 output from port 1 can be (Right now ) is independently controlled (Equation (14)), the output power P2 of port 2 is given by (Right now ) independent control (Equation (15)), such as Figure 3B At this time, the resonant capacitor C connected in parallel in ports 1 and 2 r1 , C r2 The number N1 and N2 can be flexibly set according to the required transmission power.

[0089] Figure 3A and Figure 3B The power decoupling between port 1 and port 2 is taken as an example, but the present invention is not limited thereto. There are three power decoupling situations in the TAB converter. Figure 4 The power flow directions under three operating modes are given.

[0090] Figure 4 The operation mode ① in FIG. 1 corresponds to the power decoupling between port 1 and port 2 described in the present embodiment. In this case, as described above, by adjusting the resonant capacitor C connected in parallel to port 3,r3 The number of N3 makes its resonant frequency f r3 Equal to the operating frequency f of the TAB converter s , thereby offsetting the power decoupling component between ports 1 and 2, achieving power decoupling between ports 1 and 2, so that each power output of the system can be regulated by a separate control loop.

[0091] Figure 4 Operation mode ② in FIG. 2 corresponds to the power decoupling between port 1 and port 3. Similarly, by adjusting the resonant capacitor C connected in parallel to port 2, r2 The number of N2 makes its resonant frequency f r2 Equal to the operating frequency f of the TAB converter s , thereby offsetting the power decoupling components between ports 1 and 3, achieving power decoupling between ports 1 and 3, so that each power output of the system can be regulated by a separate control loop.

[0092] Operation mode ③ corresponds to the power decoupling between port 2 and port 3. Similarly, by adjusting the resonant capacitor C connected in parallel to port 1 r1 The number of N1 makes its resonant frequency f r1 Equal to the operating frequency f of the TAB converter s , thereby canceling out the power decoupling component between ports 2 and 3, achieving power decoupling between ports 2 and 3, so that each power output of the system can be regulated by a separate control loop.

[0093] In summary, the hardware power decoupling strategy of this embodiment can achieve a change in the resonant frequency of a port by changing the number of resonant capacitors connected in parallel in a certain port. By making its resonant frequency equal to the operating frequency of the TAB converter, the power coupling component between the other two ports is offset, power decoupling is achieved, and ultimately the power output of each port can be adjusted by a separate control loop. Therefore, topological level power decoupling can be achieved by adjusting the resonant capacitance values ​​of the three ports. There is no need for complex software decoupling strategies or adding additional inductors. Resonant hardware decoupling can be achieved by controlling the number of switches connected in series with the resonant capacitor at each port according to the required transmission power.

[0094] According to the decoupling control method of the three active bridge converters in the embodiment of the present invention, topological level power decoupling is achieved by adjusting the resonant capacitance values ​​of the three ports. Complex software decoupling strategies are no longer required, and there is no need to add additional inductors. Resonant hardware decoupling can be achieved by controlling the number of switches connected in series with the resonant capacitors at each port according to the required transmission power. This provides greater adjustment freedom and can adapt to different application requirements.

[0095] In addition, by controlling the switching state of the switch tube connected in series with the resonant capacitor in the resonant cavity of each port, the resonant capacitor of each port can be accurately adjusted so that the resonant cavity of each port can operate at the required frequency, thereby improving the efficiency and stability of power transmission.

[0096] The three-active-bridge converter decoupling control method and the three-active-bridge converter of the present invention are applicable to a photovoltaic energy storage system, can better adapt to the changing power requirements in photovoltaic power generation and energy storage systems, and improve the overall performance and reliability of the system.

[0097] It should be understood that the above description is illustrative and not restrictive. For example, the above embodiments (and / or their various aspects) can be used in combination with each other. In addition, without departing from the scope of the present disclosure, many modifications can be made to adapt specific conditions or materials to the teachings of the various embodiments of the present disclosure. Although the size and type of the material described herein are used to define the parameters of the various embodiments of the present disclosure, the various embodiments are not meant to be restrictive, but exemplary embodiments. In reading the above description, many other embodiments are obvious to those skilled in the art. Therefore, the scope of the various embodiments of the present disclosure should be determined with reference to the attached claims, and the full range of equivalent forms claimed by these claims.

Claims

1. A decoupling control method for a three-active bridge converter, characterized in that: The first port, the second port and the third port of the three active bridge converter are coupled via a transformer. The first port, the second port and the third port all have a resonant cavity, and the resonant cavity includes a switch-controlled resonant capacitor and a resonant inductor with adjustable capacitance value. By adjusting the capacitance value of the third port, the resonant frequency of the third port is made to be the operating frequency of the three-active bridge converter, thereby achieving power decoupling between the first port and the second port.

2. The decoupling control method of the three active bridge converter according to claim 1, characterized in that: The switch-controlled resonant capacitor comprises: a plurality of parallel-connected resonant capacitors; and A switch tube connected to each of the resonant capacitors, In the third port, the number of the resonant capacitors connected in parallel in the switch-controlled resonant capacitor is changed by controlling the on-off of the switch tube, thereby adjusting the resonant frequency of the third port.

3. The decoupling control method of the three-active-bridge converter according to claim 2, characterized in that: By controlling the on / off of the switch tube in the first port or the second port, the capacitance value of the first port or the second port is adjusted so that the resonant frequency of the first port or the second port is a preset specified frequency.

4. The decoupling control method for a triple active bridge converter according to any one of claims 1 to 3, characterized in that: The switch tube is composed of two source-source connected MOSFET tubes.

5. The decoupling control method for a triple active bridge converter according to any one of claims 1 to 3, characterized in that: The plurality of resonant capacitors connected in parallel in each port have the same capacitance value.

6. The decoupling control method for a triple active bridge converter according to any one of claims 1 to 3, characterized in that: The inductance value of the resonant inductor is fixed.

7. The decoupling control method of the three active bridge converter according to claim 6, characterized in that: When the first port and the second port are decoupled, the resonant frequency of the resonant cavity of the third port satisfies: Among them, f s : The operating frequency of the three active bridge converters; f r3 : The resonant frequency of the resonant cavity of the third port L r3 : the inductance value of the resonant inductor of the third port; C r3 : the capacitance value of the resonant capacitor of the third port; N3: the number of the resonant capacitors connected in parallel through the switch tube in the switch-controlled resonant capacitor of the third port.

8. The decoupling control method for a triple active bridge converter according to any one of claims 1 to 3, characterized in that: After the power decoupling, the transmission power of the first port is controlled by the phase angle between the input voltages of the first port and the third port, and the transmission power of the second port is controlled by the phase angle between the input voltages of the second port and the third port.

9. The decoupling control method of the three active bridge converter according to claim 8, characterized in that: Closed-loop power control is performed on the transmission power of the first port and the transmission power of the second port, with a specified reference power as input and actual output power of each of the first port and the second port as output.

10. The decoupling control method of the three active bridge converter according to claim 9, characterized in that: The first port and the second port are located on the primary side of the transformer, and the third port is located on the secondary side of the transformer.

11. A triple active bridge converter, characterized in that: comprising a first port, a second port and a third port coupled via a transformer, The first port, the second port and the third port all have a resonant cavity, and the resonant cavity includes a switch-controlled resonant capacitor and a resonant inductor with adjustable capacitance value. When power decoupling is performed on the first port and the second port, the capacitance value of the third port is adjusted so that the resonant frequency of the third port is the operating frequency of the three-active bridge converter.

12. The triple active bridge converter according to claim 11, characterized in that: The switch-controlled resonant capacitor comprises: a plurality of parallel-connected resonant capacitors; and A switch tube connected to each of the resonant capacitors, In the third port, the number of the resonant capacitors connected in parallel in the switch-controlled resonant capacitor is changed by controlling the on-off of the switch tube, thereby adjusting the resonant frequency of the third port.

13. The triple active bridge converter according to claim 12, characterized in that: By controlling the on / off of the switch tube in the first port or the second port, the capacitance value of the first port or the second port is adjusted so that the resonant frequency of the first port or the second port is a preset specified frequency.

14. A photovoltaic system, characterized in that: Comprising a triple active bridge converter as claimed in any one of claims 11 to 13.

Images