Three-port dc-ac converter based on interleaved boost and dual active bridge

Abstract

The application discloses a three-port DC-AC converter based on interleaved Boost and double active bridge, which comprises a transformer, a first bridge arm, a second bridge arm, a first inductor, a first capacitor, a first DC port, a second DC port, a third bridge arm, a fourth bridge arm, a second inductor, a second capacitor, a full-bridge inverter circuit, a filter circuit and an AC port. The switching signals of two switching tubes contained in the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are complementary. The three-port DC-AC converter realizes two-way DC input under the condition of fewer circuit devices, and greatly simplifies the circuit structure under the same application function.

Description

Technical Field

[0001] This application relates to the technical field of circuits, and more particularly to a three-port DC-AC converter based on interleaved boost and dual active bridge. Background Technology

[0002] The dual active bridge single-stage DC-AC converter is a widely used circuit device in recent years. It achieves bidirectional buck-boost AC-DC conversion through a single-stage structure and enables soft-switching operation of all power switching devices. Furthermore, because it does not contain large-capacity electrolytic capacitors, its power density and lifespan are significantly improved compared to a two-stage structure. Therefore, the dual active bridge single-stage DC-AC converter's advantages, such as bidirectional wide voltage conversion range, high efficiency, long lifespan, and high power density, are well-suited to the specific needs of AC grid-connected energy storage systems and have broad application prospects.

[0003] However, traditional dual-active-bridge single-stage DC-AC converters typically only have one DC input port on the DC side. If multiple DC inputs are required, multiple DC-DC topologies often need to be connected in parallel, resulting in a larger number of components and higher costs. Multi-port converters (MPCs) are an important component of renewable energy-based power systems, enabling multiple DC inputs with fewer components, thus helping to solve the aforementioned problems. However, existing MPCs are generally used for DC-to-DC power conversion. When renewable energy supplies power to the grid or any AC equipment, an additional DC-AC stage is needed. Therefore, existing dual-active-bridge single-stage DC-AC converters often suffer from complex circuit structures due to the need for multiple DC-DC topologies in parallel when dealing with situations with multiple DC inputs, such as photovoltaic power generation. Summary of the Invention

[0004] This application provides a three-port DC-AC converter based on interleaved boost and dual active bridge, which aims to solve the problem of complex circuit structure caused by the parallel use of multiple DC-DC topologies in traditional dual active bridge single-stage DC-AC converters when facing multiple DC inputs.

[0005] To address the aforementioned technical problems, this application discloses a three-port DC-AC converter based on interleaved boost and dual active bridge, comprising: A transformer includes a first winding and a second winding, the first winding including a first end and a second end, and the second winding including a third end and a fourth end; The first bridge arm includes a first switch and a second switch connected in series, and the first switch and the second switch are connected to form a first connection point; The second bridge arm includes a third switch and a fourth switch connected in series. The third switch and the fourth switch are connected to form a second connection point. The second connection point is electrically connected to the second end of the first winding. The second bridge arm is connected in parallel with the first bridge arm to form the third connection point and the fourth connection point. A first inductor, one end of which is electrically connected to the first end of the first winding, and the other end of which is electrically connected to the first connection point; A first capacitor, the two ends of which are electrically connected to the third connection point and the fourth connection point, respectively; The first DC port, the output of which is electrically connected to the third connection point and the fourth connection point respectively; The second DC port has its output terminal electrically connected to the first connection point, the second connection point, and the fourth connection point, respectively. The third bridge arm includes a fifth switch and a sixth switch connected in series, and the fifth switch and the sixth switch are connected to form a fifth connection point; The fourth bridge arm includes a seventh switch and an eighth switch connected in series. The seventh switch and the eighth switch are connected to form a sixth connection point. The sixth connection point is electrically connected to the fourth end of the second winding. The fourth bridge arm is connected in parallel with the third bridge arm to form the seventh connection point and the eighth connection point. The second inductor has one end electrically connected to the third end of the second winding and the other end electrically connected to the fifth connection point. The second capacitor is electrically connected to the seventh connection point and the eighth connection point, respectively. A full-bridge inverter circuit includes a fifth terminal, a sixth terminal, a seventh terminal, and an eighth terminal, wherein the fifth terminal is electrically connected to the seventh connection point, and the sixth terminal is electrically connected to the eighth connection point; A filter circuit, wherein the input terminals of the filter circuit are electrically connected to the seventh terminal and the eighth terminal, respectively; An AC port, wherein the input terminal of the AC port is electrically connected to the output terminal of the filter circuit; In this configuration, the switching signals of the two switching transistors included in the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm are complementary.

[0006] The three-port DC-AC converter based on interleaved Boost and dual active bridges, wherein the duty cycle of the switching signal of one of the switching transistors on at least one of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm is a preset threshold.

[0007] The three-port DC-AC converter based on interleaved Boost and dual active bridges, wherein the duty cycle of the switching signals of the two switching transistors on each of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm is a preset threshold, wherein the preset threshold is 50%.

[0008] The three-port DC-AC converter based on interleaved boost and dual active bridge further includes a third inductor and a fourth inductor. Wherein, one end of the third inductor is electrically connected to the first connection point, the other end of the third inductor is electrically connected to the fourth inductor to form a ninth connection point, one end of the fourth inductor is electrically connected to the second connection point, and the ninth connection point is electrically connected to the output terminal of the second DC port.

[0009] The three-port DC-AC converter based on interleaved Boost and dual active bridge is wherein the input terminals of the first DC port and the second DC port are electrically connected to the two PV terminals of the photovoltaic panel, respectively, and the output terminal of the AC port is connected to the power grid.

[0010] The aforementioned three-port DC-AC converter based on interleaved boost and dual active bridge, wherein the input terminal of the first DC port is electrically connected to a battery, the input terminal of the second DC port is electrically connected to the PV terminal of a photovoltaic panel, and the output terminal of the AC port is connected to the power grid; or The input terminal of the first DC port is electrically connected to the PV terminal of the photovoltaic panel, the input terminal of the second DC port is electrically connected to the battery, and the output terminal of the AC port is connected to the power grid.

[0011] The three-port DC-AC converter based on interleaved Boost and dual active bridge, wherein the full-bridge inverter circuit includes a fifth bridge arm and a sixth bridge arm, and the fifth bridge arm and the sixth bridge arm are connected in parallel between the seventh connection point and the eighth connection point; The fifth bridge arm includes a ninth switch and a tenth switch connected in series. The ninth switch and the tenth switch are connected to form a tenth connection point, which is electrically connected to the input terminal of the filter circuit. The sixth bridge arm includes an eleventh switch and a twelfth switch connected in series. The eleventh switch and the twelfth switch are connected to form an eleventh connection point, which is electrically connected to the input terminal of the filter circuit. The switching signals of the two switches contained in the fifth bridge arm and the sixth bridge arm are complementary, and the duty cycle of at least one switch in the fifth bridge arm and the sixth bridge arm is 50%.

[0012] The three-port DC-AC converter based on interleaved Boost and dual active bridge is wherein the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch, and the twelfth switch are any one of diodes, MOSFETs, and thyristors.

[0013] The three-port DC-AC converter based on interleaved Boost and dual active bridge is wherein the ninth and tenth switching transistors are thyristors.

[0014] The three-port DC-AC converter based on interleaved Boost and dual active bridge, wherein the filter circuit includes a fifth inductor, a sixth inductor and a third capacitor; Wherein, one end of the fifth inductor is electrically connected to the tenth connection point, the other end of the fifth inductor is electrically connected to the sixth inductor to form the twelfth connection point, one end of the sixth inductor is electrically connected to the input terminal of the AC port, one end of the third capacitor is electrically connected to the twelfth connection point, and the other end of the third capacitor is electrically connected to the eleventh connection point and the input terminal of the AC port, respectively.

[0015] This application discloses a three-port DC-AC converter based on interleaved Boost and dual active bridges. The circuit includes a transformer, a first bridge arm, a second bridge arm, a first inductor, a first capacitor, a first DC port, a second DC port, a third bridge arm, a fourth bridge arm, a second inductor, a second capacitor, a full-bridge inverter circuit, a filter circuit, and an AC port. The switching signals of the two transistors included in the first, second, third, and fourth bridge arms are complementary. This three-port DC-AC converter allows for DC input via either the first or second DC port, achieving two DC inputs with fewer circuit components, significantly simplifying the circuit structure for the same application function. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A circuit diagram of a three-port DC-AC converter based on interleaved Boost and dual active bridge provided for embodiments of this application; Figure 2The equivalent circuit structure diagram of a three-port DC-AC converter based on interleaved Boost and dual active bridge provided for embodiments of this application; Figure 3 Another equivalent circuit diagram of a three-port DC-AC converter based on interleaved Boost and dual active bridge provided in the embodiments of this application; Figure 4 Another equivalent circuit diagram of a three-port DC-AC converter based on interleaved Boost and dual active bridge provided in the embodiments of this application; Figure 5 Another equivalent circuit diagram of a three-port DC-AC converter based on interleaved Boost and dual active bridge provided in the embodiments of this application.

[0018] Figure reference numerals: 20, Full-bridge inverter circuit; 30, Filter circuit; Port-1, First DC port; Port-2, Second DC port; Port-3, AC port; L1, First inductor; L2, Second inductor; L3, Third inductor; L4, Fourth inductor; L5, Fifth inductor; L6, Sixth inductor; S1, First switch; S2, Second switch; S3, Third switch; S4, Fourth switch; S5, Fifth switch; S6, Sixth switch; S 7. Seventh switch; S8. Eighth switch; Q1. Ninth switch; Q2. Tenth switch; S9. Eleventh switch; S10. Twelfth switch; C1. First capacitor; C3. Second capacitor; C2. Third capacitor; T. Transformer; 1. First connection point; 2. Second connection point; 3. Third connection point; 4. Fourth connection point; 5. Fifth connection point; 6. Sixth connection point; 7. Seventh connection point; 8. Eighth connection point; 9. Ninth connection point; 10. Tenth connection point. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0023] This application discloses a three-port DC-AC converter based on interleaved boost and dual active bridge, such as... Figure 1As shown, the system includes: a transformer T, comprising a first winding and a second winding, the first winding including a first end and a second end, and the second winding including a third end and a fourth end; a first bridge arm, comprising a first switch S1 and a second switch S2 connected in series, the first switch S1 and the second switch S2 being connected to form a first connection point 1; a second bridge arm, comprising a third switch S3 and a fourth switch S4 connected in series, the third switch S3 and the fourth switch S4 being connected to form a second connection point 2, the second connection point 2 being electrically connected to the second end of the first winding; and the second bridge arm being connected in parallel with the first bridge arm to form a third connection point 3 and a fourth connection point 4. Point 4; First inductor L1, one end of the first inductor L1 is electrically connected to the first end of the first winding, and the other end of the first inductor L1 is electrically connected to the first connection point 1; First capacitor C1, the two ends of the first capacitor C1 are respectively electrically connected to the third connection point 3 and the fourth connection point 4; First DC port Port-1, the output terminal of the first DC port Port-1 is respectively electrically connected to the third connection point 3 and the fourth connection point 4; Second DC port Port-2, the output terminal of the second DC port Port-2 is respectively electrically connected to the first connection point 1, the second connection point 2 and the fourth connection point 4; Third bridge arm, including series The fifth switch S5 and the sixth switch S6 are connected in series to form a fifth connection point 5; the fourth bridge arm includes a seventh switch S7 and an eighth switch S8 connected in series to form a sixth connection point 6, which is electrically connected to the fourth terminal of the second winding; the fourth bridge arm is connected in parallel with the third bridge arm to form a seventh connection point 7 and an eighth connection point 8; a second inductor L2, one end of which is electrically connected to the third terminal of the second winding, and the other end of which is electrically connected to the fifth connection point 5; a second capacitor C3, ... The two ends of the second capacitor C3 are electrically connected to the seventh connection point 7 and the eighth connection point 8, respectively; the full-bridge inverter circuit 20 includes a fifth terminal, a sixth terminal, a seventh terminal, and an eighth terminal, with the fifth terminal electrically connected to the seventh connection point 7 and the sixth terminal electrically connected to the eighth connection point 8; the filter circuit 30 has its input terminals electrically connected to the seventh terminal and the eighth terminal, respectively; the AC port Port-3 has its input terminal electrically connected to the output terminal of the filter circuit 30; wherein, the switching signals of the two switching transistors included in the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm are complementary.

[0024] The three-port DC-AC converter proposed in this application consists of three circuit parts, including a front-end boost converter, a full-bridge inverter circuit 20, and a filter circuit 30. The boost converter is a three-port DC-DC boost circuit based on interleaved boost and dual active bridge. The first DC port Port-1 and the second DC port Port-2 of the boost converter are both DC input ports, that is, the boost converter has two DC input terminals. The input voltage can be boosted and the bidirectional flow of energy can be achieved by controlling the switching signals (such as controlling the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7, and the eighth switch S8 respectively) through the output switching signals of the MCU control signal. The subsequent DC-AC conversion is configured as a full-bridge inverter circuit 20. The AC power output by the full-bridge inverter circuit 20 is filtered by the filter circuit 30 to make the output AC power meet the grid connection requirements. The two connection terminals of the filter circuit 30 are the phase line connection terminal and the neutral line connection terminal, respectively. These two connection terminals combine to form the AC port Port-3. Therefore, the aforementioned three-port DC-AC converter includes three ports: the first DC port Port-1, the second DC port Port-2, and the AC port Port-3. The introduction of the three ports allows the converter structure to achieve two DC inputs with fewer required components. Furthermore, the introduction of the interleaved Boost structure enables DC-to-DC energy transfer compared to traditional topologies, without the need for transformer T isolation. Therefore, this three-port DC-AC converter does not require a three-winding transformer T; only one transformer T is needed to achieve the function of two DC inputs, significantly simplifying the circuit structure. In this circuit, the switching signals of the two switches on one bridge arm are complementary; that is, when one switch is on, the other switch is off.

[0025] In a more specific embodiment, the duty cycle of the switching signal of one of the switching transistors on at least one of the first, second, third, and fourth bridge arms is a preset threshold. Specifically, the duty cycle of the switching signals of the two switching transistors on each of the first, second, third, and fourth bridge arms is a preset threshold of 50%.

[0026] Furthermore, assuming the duty cycles of the switching signals of the two switching transistors on the bridge arm are complementary, the duty cycles of the switching signals of the two switching transistors on the bridge arm can also be set to a preset threshold. Furthermore, to improve the circuit conversion effect, the duty cycles of the switching signals of the two switching transistors on all bridge arms can be set to a preset threshold, where the preset threshold can be set to 50%.

[0027] In a more specific embodiment, a third inductor L3 and a fourth inductor L4 are also included; wherein one end of the third inductor L3 is electrically connected to the first connection point 1, the other end of the third inductor L3 is electrically connected to the fourth inductor L4 to form a ninth connection point 9, one end of the fourth inductor L4 is electrically connected to the second connection point 2, and the ninth connection point 9 is electrically connected to the output terminal of the second DC port Port-2.

[0028] In a more specific embodiment, the input terminals of the first DC port Port-1 and the second DC port Port-2 are electrically connected to the two PV terminals of the photovoltaic panel, respectively, and the output terminal of the AC port Port-3 is connected to the power grid. Specifically, the input terminal of the first DC port Port-1 is electrically connected to a battery, the input terminal of the second DC port Port-2 is electrically connected to the PV terminal of the photovoltaic panel, and the output terminal of the AC port Port-3 is connected to the power grid; or the input terminal of the first DC port Port-1 is electrically connected to the PV terminal of the photovoltaic panel, the input terminal of the second DC port Port-2 is electrically connected to a battery, and the output terminal of the AC port Port-3 is connected to the power grid.

[0029] This three-port DC-AC converter has diverse and flexible applications. It can be used in photovoltaic micro-inverters. The first DC port (Port-1) and the second DC port (Port-2) can be connected to the PV1 terminal (first photovoltaic input terminal) and the PV2 terminal (second photovoltaic input terminal) of the photovoltaic panel, respectively. The AC port (Port-3) serves as the output port, connected to the power grid, allowing PV1 and PV2 to supply energy to the grid together, achieving a structure similar to a one-to-two splitter configuration in a micro-inverter. Alternatively, the first DC port (Port-1) can be connected to a battery, the second DC port (Port-2) to the PV terminal (photovoltaic input terminal) of the photovoltaic panel, and the AC port (Port-3) to the power grid. This allows the photovoltaic panel to generate electricity and transmit it to the grid, and it can also store the energy of the photovoltaic panel in the battery by controlling the operating mode. Furthermore, it can control the photovoltaic panel and the battery to charge the grid together when the output voltage of the photovoltaic panel is too low, offering flexible and diverse operating modes.

[0030] In a more specific embodiment, the full-bridge inverter circuit 20 includes a fifth bridge arm and a sixth bridge arm, which are connected in parallel between the seventh connection point 7 and the eighth connection point 8. The fifth bridge arm includes a ninth switch Q1 and a tenth switch Q2 connected in series, forming a tenth connection point 10, which is electrically connected to the input terminal of the filter circuit 30. The sixth bridge arm includes an eleventh switch S9 and a twelfth switch S10 connected in series, forming an eleventh connection point, which is electrically connected to the input terminal of the filter circuit 30. The switching signals of the two switches in the fifth and sixth bridge arms are complementary, and the duty cycle of at least one switch in the fifth and sixth bridge arms is 50%. Wherein, the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7, the eighth switch S8, the ninth switch Q1, the tenth switch Q2, the eleventh switch S9, and the twelfth switch S10 are any one of diodes, MOSFETs, and thyristors.

[0031] Specifically, the switching transistors included in the boost converter can all be MOSFETs, and the switching signal is input from the gate of the MOSFET; the switching transistors included in the boost converter can also be diodes with unidirectional conduction function, in which case a control switch that can receive the switching signal is connected in series on one side of the diode, and the conduction and disconnection of the control switch are controlled, thereby achieving the purpose of controlling the duty cycle of the diode through the switching signal.

[0032] In a typical embodiment, such as Figure 1As shown, the boost converter contains MOSFETs as the switching transistors. The first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7, and the eighth switch S8 are the first MOSFET, the second MOSFET, the third MOSFET, the fourth MOSFET, the fifth MOSFET, the sixth MOSFET, the seventh MOSFET, and the eighth MOSFET, respectively. The drain of the first MOSFET is connected to the drain of the third MOSFET, and the connection point serves as the first connection terminal of the boost converter; one end of the third inductor L3 is connected to one end of the fourth inductor L4, and the connection point serves as the second connection terminal of the boost converter; the source of the second MOSFET is connected to the source of the fourth MOSFET, and the connection point serves as the third connection terminal of the boost converter; the first connection terminal and the third connection terminal combine to form the first DC port Port-1; the second connection terminal and the third connection terminal combine to form the second DC port Port-2; the source of the first MOSFET is connected to the drain of the second MOSFET, the other end of the third inductor L3, and one end of the first inductor L1; the source of the third MOSFET is connected to the drain of the fourth MOSFET, the other end of the fourth inductor L4, and one end of the first winding of the transformer T; the other end of the first inductor L1 is connected to the transformer... The other end of the first winding of transformer T is connected; one end of the second winding of transformer T is connected to one end of the second inductor L2, and the other end of the second inductor L2 is connected to the source of the fifth MOSFET and the drain of the sixth MOSFET; the other end of the second winding of transformer T is connected to the source of the seventh MOSFET and the drain of the eighth MOSFET; the drain of the fifth MOSFET is connected to the drain of the sixth MOSFET, and the connection point serves as the first conversion terminal of the boost converter, connected to the first inverter terminal of the full-bridge inverter circuit 20; the source of the sixth MOSFET is connected to the source of the eighth MOSFET, and the connection point serves as the second conversion terminal of the boost converter, connected to the second inverter terminal of the full-bridge inverter circuit 20; the two inverter connection terminals of the full-bridge inverter circuit 20 are respectively connected to the two filter connection terminals of the filter circuit 30; the two connection terminals of the filter circuit 30 are combined to form AC port Port-3.

[0033] The aforementioned three-port DC-AC converter includes three ports: a first DC port (Port-1), a second DC port (Port-2), and an AC port (Port-3). It can transfer energy from the first DC port (Port-1) to the AC port (Port-3), meaning that the first DC port (Port-1) receives DC power and the AC port (Port-3) outputs AC power; or it can transfer energy from the second DC port (Port-2) to the AC port (Port-3), meaning that the second DC port (Port-2) receives DC power and the AC port (Port-3) outputs AC power; it can also transfer energy from the second DC port (Port-2) to the first DC port (Port-1), meaning that the second DC port (Port-2) receives DC power and the first DC port (Port-1) outputs DC power; furthermore, it can transfer energy from both the first DC port (Port-1) and the second DC port (Port-2) to the AC port (Port-3) simultaneously, meaning that both the first DC port (Port-1) and the second DC port (Port-2) receive DC power simultaneously and the AC port (Port-3) outputs AC power. In other words, the aforementioned three-port DC-AC converter can realize four application functions, thereby greatly expanding the application scenarios of the three-port DC-AC converter and improving the flexibility of circuit use.

[0034] The control method of the above-mentioned three-port DC-AC converter is relatively simple and is basically the same as that of the traditional dual active bridge DC-AC converter. First, the duty cycle of all switching signals is configured to be constant at 50%, ensuring that the switching signals of the two switches on the same bridge arm are complementary (if one switch is on, the other is off). The phase shift angle of the switching signal between the first switch S1 and the fourth switch S4 is defined as D1, the phase shift angle between the first switch S1 and the fifth switch S5 is defined as D2, and the phase shift angle between the fifth switch S5 and the eighth switch S8 is defined as D3. Simultaneously, D1 and D3 are ensured to be consistent. Thus, by controlling the values ​​of D1 (D3) and D2, the three-port DC-AC converter can switch between the above-mentioned operating states. The first operating mode involves energy transfer from the first DC port (Port-1) to the AC port (Port-3), and its equivalent circuit diagram is shown below. Figure 2 As shown; the second operating mode involves energy transfer from the second DC port (Port-2) to the AC port (Port-3), and its equivalent circuit diagram is shown below. Figure 3 As shown; the third operating mode involves energy transfer from the second DC port (Port-2) to the first DC port (Port-1), and its equivalent circuit diagram is shown below. Figure 4 As shown; the fourth operating mode involves energy being simultaneously transferred from the first DC port (Port-1) and the second DC port (Port-2) to the AC port (Port-3), and its equivalent circuit diagram is shown below. Figure 5 As shown.

[0035] In a more specific embodiment, the ninth switch Q1 and the tenth switch Q2 are thyristors. Specifically, the filter circuit 30 includes a fifth inductor L5, a sixth inductor L6, and a third capacitor C2; wherein, one end of the fifth inductor L5 is electrically connected to the tenth connection point 10, the other end of the fifth inductor L5 is electrically connected to the sixth inductor L6 to form the twelfth connection point, one end of the sixth inductor L6 is electrically connected to the input terminal of the AC port Port-3, one end of the third capacitor C2 is electrically connected to the twelfth connection point, and the other end of the third capacitor C2 is electrically connected to the eleventh connection point and the input terminal of the AC port Port-3, respectively.

[0036] The full-bridge inverter circuit 20 consists of the ninth switch Q1, the tenth switch Q2, the eleventh switch S9, and the twelfth switch S10. The ninth switch Q1 and the tenth switch Q2 are thyristors. The use of thyristors to replace the MOSFETs in the existing technology effectively reduces the overall production cost of the circuit while ensuring circuit performance.

[0037] In a more specific embodiment, the filter circuit 30 includes a fifth inductor L5, a sixth inductor L6, and a third capacitor C2; one end of the fifth inductor L5 serves as the first filter connection terminal of the filter circuit 30 and is connected to the first inverter connection terminal of the full-bridge inverter circuit 20; the other end of the fifth inductor L5 is connected to one end of the sixth inductor L6 and one end of the second capacitor C3, and the other end of the second capacitor C3 serves as the second filter connection terminal of the filter circuit 30 and is connected to the second inverter connection terminal of the full-bridge inverter circuit 20; the other end of the sixth inductor L6 serves as the phase line connection terminal of the filter circuit 30, and the second filter connection terminal serves as the neutral line connection terminal of the filter circuit 30.

[0038] Furthermore, to improve the filtering effect of the filter circuit 30, the filter circuit 30 can be configured to consist of a fifth inductor L5, a sixth inductor L6, and a second capacitor C3. With this configuration, noise in the AC power output from the first inverter connection terminal and the second inverter connection terminal can be effectively filtered out, thereby improving the quality of the AC power output through the AC port Port-3.

[0039] The three-port DC-AC converter based on interleaved boost and dual active bridge proposed in this application can achieve multiple DC inputs with fewer components and can simultaneously transfer energy from the DC side to the DC side and from the DC side to the AC side. Furthermore, the use of a dual-winding transformer T can replace the three-winding transformer T in traditional multi-port converters, compressing the overall size of the circuit structure and thus solving the problem of designing a three-winding transformer T in a compact package under high power flow conditions.

[0040] This application discloses a three-port DC-AC converter based on interleaved Boost and dual active bridges. The circuit includes a transformer, a first bridge arm, a second bridge arm, a first inductor, a first capacitor, a first DC port, a second DC port, a third bridge arm, a fourth bridge arm, a second inductor, a second capacitor, a full-bridge inverter circuit, a filter circuit, and an AC port. The switching signals of the two transistors included in the first, second, third, and fourth bridge arms are complementary. This three-port DC-AC converter allows for DC input via either the first or second DC port, achieving two DC inputs with fewer circuit components, significantly simplifying the circuit structure for the same application function.

[0041] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A three-port DC-AC converter based on interleaved Boost and dual active bridge, characterized in that, include: A transformer includes a first winding and a second winding, the first winding including a first end and a second end, and the second winding including a third end and a fourth end; The first bridge arm includes a first switch and a second switch connected in series, and the first switch and the second switch are connected to form a first connection point; The second bridge arm includes a third switch and a fourth switch connected in series. The third switch and the fourth switch are connected to form a second connection point. The second connection point is electrically connected to the second end of the first winding. The second bridge arm is connected in parallel with the first bridge arm to form the third connection point and the fourth connection point. A first inductor, one end of which is electrically connected to the first end of the first winding, and the other end of which is electrically connected to the first connection point; A first capacitor, the two ends of which are electrically connected to the third connection point and the fourth connection point, respectively; The first DC port, the output of which is electrically connected to the third connection point and the fourth connection point respectively; The second DC port has its output terminal electrically connected to the first connection point, the second connection point, and the fourth connection point, respectively. The third bridge arm includes a fifth switch and a sixth switch connected in series, and the fifth switch and the sixth switch are connected to form a fifth connection point; The fourth bridge arm includes a seventh switch and an eighth switch connected in series. The seventh switch and the eighth switch are connected to form a sixth connection point. The sixth connection point is electrically connected to the fourth end of the second winding. The fourth bridge arm is connected in parallel with the third bridge arm to form the seventh connection point and the eighth connection point. The second inductor has one end electrically connected to the third end of the second winding and the other end electrically connected to the fifth connection point. The second capacitor is electrically connected to the seventh connection point and the eighth connection point, respectively. A full-bridge inverter circuit includes a fifth terminal, a sixth terminal, a seventh terminal, and an eighth terminal, wherein the fifth terminal is electrically connected to the seventh connection point, and the sixth terminal is electrically connected to the eighth connection point; A filter circuit, wherein the input terminals of the filter circuit are electrically connected to the seventh terminal and the eighth terminal, respectively; An AC port, wherein the input terminal of the AC port is electrically connected to the output terminal of the filter circuit; A third inductor and a fourth inductor, one end of the third inductor being electrically connected to the first connection point, the other end of the third inductor being electrically connected to the fourth inductor to form a ninth connection point, one end of the fourth inductor being electrically connected to the second connection point, and the ninth connection point being electrically connected to the output terminal of the second DC port; In this case, the switching signals of the two switching transistors included in the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm are complementary; The full-bridge inverter circuit includes a fifth bridge arm and a sixth bridge arm, and the fifth bridge arm and the sixth bridge arm are connected in parallel between the seventh connection point and the eighth connection point; The fifth bridge arm includes a ninth switch and a tenth switch connected in series. The ninth switch and the tenth switch are connected to form a tenth connection point, which is electrically connected to the input terminal of the filter circuit. The sixth bridge arm includes an eleventh switch and a twelfth switch connected in series. The eleventh switch and the twelfth switch are connected to form an eleventh connection point, which is electrically connected to the input terminal of the filter circuit. The switching signals of the two switches included in the fifth bridge arm and the sixth bridge arm are complementary, and the duty cycle of at least one switch in the fifth bridge arm and the sixth bridge arm is 50%. The filter circuit includes a fifth inductor, a sixth inductor, and a third capacitor; Wherein, one end of the fifth inductor is electrically connected to the tenth connection point, the other end of the fifth inductor is electrically connected to the sixth inductor to form the twelfth connection point, one end of the sixth inductor is electrically connected to the input terminal of the AC port, one end of the third capacitor is electrically connected to the twelfth connection point, and the other end of the third capacitor is electrically connected to the eleventh connection point and the input terminal of the AC port, respectively.

2. The three-port DC-AC converter based on interleaved Boost and dual active bridges according to claim 1, characterized in that, The duty cycle of the switching signal of one of the switching transistors on at least one of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm is a preset threshold.

3. The three-port DC-AC converter based on interleaved Boost and dual active bridge according to claim 1 or 2, characterized in that, The duty cycle of the switching signals of the two switching transistors on each of the first bridge arm, the second bridge arm, the third bridge arm, and the fourth bridge arm is a preset threshold, which is 50%.

4. The three-port DC-AC converter based on interleaved Boost and dual active bridges according to claim 1, characterized in that, The input terminals of the first DC port and the second DC port are electrically connected to the two PV terminals of the photovoltaic panel, respectively, and the output terminal of the AC port is connected to the power grid.

5. The three-port DC-AC converter based on interleaved Boost and dual active bridges according to claim 1, characterized in that, The input terminal of the first DC port is electrically connected to the battery, the input terminal of the second DC port is electrically connected to the PV terminal of the photovoltaic panel, and the output terminal of the AC port is connected to the power grid; or The input terminal of the first DC port is electrically connected to the PV terminal of the photovoltaic panel, the input terminal of the second DC port is electrically connected to the battery, and the output terminal of the AC port is connected to the power grid.

6. The three-port DC-AC converter based on interleaved Boost and dual active bridges according to claim 1, characterized in that, The first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch, and the twelfth switch are any one of diodes, MOSFETs, and thyristors.

7. The three-port DC-AC converter based on interleaved Boost and dual active bridges according to claim 6, characterized in that, The ninth and tenth switching transistors are thyristors.

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