Conversion circuit and control method thereof

Abstract

The invention discloses a conversion circuit and a control method thereof, which are characterized in that a shared second function group is arranged to be shared by all energy transmission paths, and meanwhile, only a third function group with the same circuit function as a first function group is configured for a newly added second energy transmission module. According to the structure, when energy is transmitted from the second direct-current interface to the alternating-current interface, the energy only needs to flow through the third functional group carried by the second direct-current interface and multiplexes the second functional group on the first energy transmission module; energy can be exchanged directly through the respective first / third functional groups and the expansion nodes without flowing through the second functional group, so that the technical problems of high system cost, large size and low energy transmission efficiency caused by repeated configuration of power units in the existing multi-stage conversion architecture are solved; the technical effects of reducing the number of power conversion stages, reducing the number of core power units, optimizing the system structure and improving the overall energy transmission efficiency are achieved.

Description

Technical Field

[0001] This invention relates to the field of power conversion, and in particular to a conversion circuit and its control method. Background Technology

[0002] With the widespread application of renewable energy, distributed energy storage, and DC loads, isolated AC-DC converter circuits that support bidirectional power flow across multiple interfaces have become key equipment in energy systems. Existing technologies generally employ a multi-stage architecture with an independent DC-DC converter for each DC interface to achieve this function, resulting in redundant system components, high costs, long energy transmission paths, and low efficiency.

[0003] Therefore, how to provide a solution to the above-mentioned technical problems is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a conversion circuit and its control method to at least solve the technical problems of high system cost, large size and low energy transmission efficiency caused by the repeated configuration of power units in existing multi-stage conversion architectures.

[0005] To solve the above-mentioned technical problems, the present invention provides a conversion circuit, comprising:

[0006] Communication interface;

[0007] Multiple DC interfaces, including a first DC interface and a second DC interface;

[0008] A first energy transmission module is disposed between the first DC interface and the AC interface. The first energy transmission module includes a first functional group and a second functional group connected in series.

[0009] The second energy transmission module is located between the second DC interface and the expansion node of the first energy transmission module. The expansion node is located at the connection between the first functional group and the second functional group. The second energy transmission module includes a third functional group, which is configured to have the same circuit function as the first functional group.

[0010] The first functional group and / or the second functional group include at least one power unit for performing power conversion operations.

[0011] Optionally, the first functional group and the second functional group are arranged sequentially according to the energy flow direction from the first DC interface to the AC interface.

[0012] Optionally, both the first functional group and the third functional group include a DC-side filter unit, a DC-side power unit, a capacitive inductor unit, and a transformer unit connected in sequence; the second functional group includes an AC-side power unit and an AC-side filter unit connected in sequence; the expansion node is located between the transformer unit and the AC-side power unit; the power unit includes an AC-side power unit and the DC-side power unit.

[0013] Optionally, the first functional group or the second functional group further includes a transformer unit, and the first functional group and / or the second functional group further includes at least one capacitive inductor unit, the capacitive inductor unit including a first inductor and a first capacitor, wherein:

[0014] The first end of the first inductor is connected to the transformer unit, and the second end of the first inductor is connected to the first capacitor.

[0015] Optionally, when the capacitive inductor unit is located on the secondary side of the transformer unit, the capacitive inductor unit further includes a second inductor, which is connected in parallel with the secondary winding of the transformer unit.

[0016] Optionally, there are multiple second DC interfaces and multiple second energy transmission modules, with each of the multiple second energy transmission modules being disposed one-to-one between the multiple second DC interfaces and the expansion node.

[0017] Optionally, the power unit includes multiple switching transistors, and the conversion circuit further includes:

[0018] A detection unit is used to detect the electrical operating parameters of the conversion circuit;

[0019] The control unit is used to control the corresponding switching transistor to perform switching actions according to the electrical operating parameters, so as to transfer energy between the AC interface and any of the DC interfaces, or between multiple DC interfaces.

[0020] This application also provides a control method for a conversion circuit, wherein the conversion circuit is as described in any of the above claims, the conversion circuit includes an AC side power unit, the AC side power unit includes at least one bridge arm, the bridge arm includes two switch groups, and the two switches in the switch groups are respectively located in the upper bridge arm and the lower bridge arm of the bridge arm, and the control method for the conversion circuit includes:

[0021] A first complementary drive signal is output to one switch group, and a second complementary drive signal is output to another switch group after a delay between the delay groups.

[0022] Wherein, the first complementary drive signal and the second complementary drive signal are both used to control one switch in the corresponding switch group to perform a disconnect action, and after a dead time delay, control the other switch to perform a turn-on action, wherein the dead time is less than the inter-group delay time.

[0023] Optionally, the control method for the conversion circuit further includes:

[0024] Obtain the AC side voltage of the conversion circuit;

[0025] Based on the polarity of the AC side voltage, determine the leading group and the lagging group in the two switching groups;

[0026] The process of outputting a first complementary drive signal to one switch group and, after a delay between switch groups, outputting a second complementary drive signal to another switch group includes:

[0027] A first complementary drive signal is output to the leading group, and a second complementary drive signal is output to the lagging group after a delay time between the delay groups.

[0028] Optionally, the control method for the conversion circuit further includes:

[0029] When the AC side voltage is greater than the absolute value of the preset threshold corresponding to the polarity, a target drive signal is output to the leading group and a second complementary drive signal is output to the lagging group. The target drive signal is used to control the two switches in the leading group to maintain the conducting state.

[0030] The process of outputting a first complementary drive signal to the leading group and, after a delay between the delay groups, outputting a second complementary drive signal to the lagging group includes:

[0031] When the AC side voltage is less than or equal to the absolute value of the preset threshold corresponding to the polarity, a first complementary drive signal is output to the leading group, and a second complementary drive signal is output to the lagging group after the delay time between the delay groups.

[0032] Optionally, the difference between the inter-group delay time and the dead time is greater than the turn-on delay time of the switching transistor.

[0033] This application provides a conversion circuit and its control method. By setting a shared second functional group for all energy transmission paths, and configuring a third functional group with identical circuit functions to the first functional group only for newly added second energy transmission modules, this architecture allows energy to flow only through its own carried third functional group and reuse the second functional group on the first energy transmission module when transferring energy from the second DC interface to the AC interface. Furthermore, when transferring energy between multiple DC interfaces, energy can be directly exchanged through their respective first / third functional groups and extension nodes without flowing through the second functional group. This solves the technical problems of high system cost and large size caused by redundant power unit configuration in existing multi-stage conversion architectures, achieving the effects of reducing the number of power conversion stages, reducing the number of core power units, optimizing system structure, and improving overall energy transmission efficiency. Attached Figure Description

[0034] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of a conversion circuit provided by the present invention;

[0036] Figure 2 This is a schematic diagram of the first functional group division provided by the present invention;

[0037] Figure 3 This is a schematic diagram of the second type of functional group division provided by the present invention;

[0038] Figure 4 This is a schematic diagram of the structure of a first energy transmission module provided by the present invention;

[0039] Figure 5 A schematic diagram of another first energy transmission module provided by the present invention;

[0040] Figure 6 This is a schematic diagram of the third type of functional group division provided by the present invention;

[0041] Figure 7 This is a schematic diagram of the fourth type of functional group division provided by the present invention;

[0042] Figure 8 This is a schematic diagram of the fifth type of functional group division provided by the present invention;

[0043] Figure 9 This is a schematic diagram of the sixth functional group division provided by the present invention;

[0044] Figure 10 This is a schematic diagram of the seventh functional group division provided by the present invention;

[0045] Figure 11 This is a schematic diagram of the eighth functional group division provided by the present invention;

[0046] Figure 12 This is a schematic diagram of the structure of the first capacitive sensing unit provided by the present invention;

[0047] Figure 13 This is a schematic diagram of the structure of the second type of capacitive sensing unit provided by the present invention;

[0048] Figure 14 This is a schematic diagram of the structure of the third type of capacitive sensing unit provided by the present invention;

[0049] Figure 15 This is a schematic diagram of the structure of the fourth type of capacitive sensing unit provided by the present invention;

[0050] Figure 16 A schematic diagram of another conversion circuit provided by the present invention;

[0051] Figure 17 This is a schematic diagram of the structure of a control system provided by the present invention;

[0052] Figure 18 A schematic diagram of a synchronous switch driving logic provided for related technologies;

[0053] Figure 19 A synchronous switch drive waveform diagram provided by the present invention;

[0054] Figure 20 This is a schematic diagram of a high-frequency driving method for Vac as a timing lead group provided by the present invention;

[0055] Figure 21 This is a schematic diagram of a high-frequency driving mechanism for a lead group when Vac is negative, provided by the present invention.

[0056] Figure 22 This is a schematic diagram of a switching advance group operating mode based on a threshold voltage provided by the present invention;

[0057] Figure 23 This is a schematic diagram of a drive where Vac is normally open for timing lead group, provided by the present invention.

[0058] Figure 24 This is a schematic diagram of a normally open lead group drive provided by the present invention when Vac is negative;

[0059] Figure 25 This invention provides a schematic diagram of a working current loop where Vac is positive for t1~t3.

[0060] Figure 26 This is a schematic diagram of the working current loop for Vac when it is positive, t3~t4, provided by the present invention;

[0061] Figure 27 This is a schematic diagram of the working current loop for Vac when it is positive, t4~t5, provided by the present invention;

[0062] Figure 28 This is a schematic diagram of the working current loop for Vac when it is positive, t5~t7, provided by the present invention;

[0063] Figure 29 This is a schematic diagram of the working current loop for Vac at time t7~t8 provided by the present invention;

[0064] Figure 30 The schematic diagram of the Vac positive time t8~t9 working current loop provided by the present invention. Detailed Implementation

[0065] The core of this invention is to provide a conversion circuit and its control method to at least solve the technical problems of high system cost, large size and low energy transmission efficiency caused by the repeated configuration of power units in existing multi-stage conversion architectures.

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] Firstly, please refer to Figure 1 The present invention provides a conversion circuit, comprising:

[0068] Communication interface;

[0069] Multiple DC interfaces, including a first DC interface and a second DC interface;

[0070] The first energy transmission module is located between the first DC interface and the AC interface. The first energy transmission module includes a first functional group and a second functional group connected in series.

[0071] The second energy transmission module is located between the second DC interface and the expansion node of the first energy transmission module. The expansion node is located at the connection between the first functional group and the second functional group. The second energy transmission module includes a third functional group, which is configured to have the same circuit function as the first functional group.

[0072] The first functional group and / or the second functional group include at least one power unit for performing power conversion operations.

[0073] In this embodiment, the conversion circuit can realize DC-AC and / or AC-DC and / or DC-DC power conversion. The conversion circuit includes an AC interface and multiple DC interfaces. The AC interface is used to connect to an AC power source, which can be of various types, including but not limited to single-phase AC and three-phase AC, with voltage levels such as 110V, 220V, and 380V. The number of AC interfaces can be one or more. The DC interfaces are used to connect to DC power sources, including but not limited to batteries, supercapacitors, photovoltaic panels, fuel cells, and DC microgrids. Any two DC interfaces can connect to different types of DC power sources or the same type of DC power source. For example, the first DC interface DC1 can be connected to a battery, and the second DC interface DC2 can be connected to a photovoltaic power source. Alternatively, both the first DC interface DC1 and the second DC interface DC2 can be connected to a battery. This embodiment does not impose any limitations on this.

[0074] The multiple DC interfaces include at least one first DC interface and at least one second DC interface. In this embodiment, the DC interface connected to the first energy transmission module is designated as the first DC interface, and the DC interface connected to the second energy transmission module is designated as the second DC interface. Accordingly, the number of first energy transmission modules can be one or more, and the number of second energy transmission modules can also be one or more.

[0075] The first energy transmission module is located between the first DC interface and the AC interface. This module includes multiple functional units connected in sequence, forming a complete power conversion link. These functional units include at least a power unit for performing power conversion operations, and may also include a filter unit for filtering, a transformer unit for transformation, etc. The power unit is composed of fully controllable switching devices (such as MOSFETs and IGBTs), and bidirectional energy flow and conversion are achieved by controlling the on and off states of these switching devices. In this embodiment, the multiple functional units connected in sequence are divided into a first functional group and a second functional group connected in sequence. For example, suppose the first energy transfer module includes five functional units, namely M1, M2, M3, M4 and M5 connected in sequence. M1, M2 and M3 can be divided into a first functional group, and M4 and M5 into a second functional group. Alternatively, M1, M2, M3 and M4 can be divided into a first functional group, and M5 into a second functional group. Of course, M5 and M4 can also be divided into a first functional group, and M3, M2 and M1 into a second functional group, and so on. Of course, in addition to the above methods, other methods can also be used, such as dividing according to the layout of the application environment, the number of devices and cost.

[0076] As an optional embodiment, the more costly and bulky functional units can be divided into the second functional group for sharing, while the necessary basic functional units can be retained in the first functional group. The selection can be made according to the actual engineering needs, and this embodiment does not limit this.

[0077] The second energy transmission module is located between the second DC interface and the expansion node of the first energy transmission module. The expansion node is located at the connection between the first functional group and the second functional group of the first energy transmission module. For example, if M1, M2, and M3 are classified as the first functional group, and M4 and M5 as the second functional group, then the expansion node is located at the connection between M3 and M4. Conversely, if M1, M2, M3, and M4 are classified as the first functional group, and M5 is classified as the second functional group, then the expansion node is located at the connection between M4 and M5. The second energy transmission module includes a third functional group. The third functional group has the same circuit function as the first functional group. As an optional embodiment, the third functional group has the same circuit topology as the first functional group. The same circuit topology includes at least identical electrical components and identical connection relationships. (Refer to...) Figure 2 As shown, assuming the first functional group includes M1, M2, and M3 connected in sequence, then the third functional group also includes M1, M2, and M3 connected in sequence. (Refer to...) Figure 3As shown, assuming the first functional group includes M1, M2, M3, and M4 connected in sequence, the third functional group also includes M1, M2, M3, and M4 connected in sequence. With this architecture, energy exchange between the second DC interface and the AC interface is achieved jointly by the third functional group of the second energy transmission module and the second functional group of the first energy transmission module. Because the second functional group of the first energy transmission module is reused, the deployment of functional units in the second energy transmission module can be reduced, effectively lowering hardware costs. This architecture is particularly suitable for applications requiring the expansion of multiple DC interfaces. When the number of DC interfaces increases, each newly added DC interface only needs to be configured with the third functional group to share the existing second functional group, avoiding redundant construction of functional units and achieving cost reduction. This effect is especially significant for converter circuits with multiple DC interfaces.

[0078] It is understood that, due to the different division methods for the multiple functional units sequentially connected in the first energy transmission module in this embodiment, there are cases where the first functional group includes one power unit for performing power conversion operations, the second functional group includes one power unit for performing power conversion operations, the first functional group includes two power units for performing power conversion operations and the second functional group does not include any power units, and the first functional group does not include any power units and the second functional group includes two power units. It is also understood that, since the third functional group of the second energy transmission module has the same circuit topology as the first functional group, when the first functional group includes one power unit for performing power conversion operations, the third functional group also includes one power unit for performing power conversion operations, and so on. Based on their position in the energy transmission path, the power units include DC-side power units and AC-side power units, wherein the DC-side power units are used to implement DC-side power conversion operations, and the AC-side power units are used to implement AC-side power conversion operations.

[0079] As an optional embodiment, there are multiple second DC interfaces and multiple second energy transmission modules, with each of the multiple second energy transmission modules being disposed one-to-one between the multiple second DC interfaces and the expansion node.

[0080] The architecture of this embodiment allows for the simultaneous connection of more DC devices, such as photovoltaic panels, batteries, and supercapacitors, eliminating the hassle and cost of equipping each device with a separate conversion circuit. Energy can be transferred not only between each DC device and the AC grid but also directly between different DC devices. For example, batteries can directly charge supercapacitors, or photovoltaic power can directly supply DC loads without first converting to AC and back, reducing the number of power conversions, minimizing energy loss during multiple conversions, and improving overall efficiency. When one DC device is not working or malfunctions, energy exchange between other devices can still proceed normally, preventing a system shutdown and improving the continuity and reliability of power supply.

[0081] The conversion circuit in this embodiment supports multiple operating modes. In AC-DC mode, power from the AC interface can be transferred to each DC interface simultaneously or selectively. In DC-AC mode, power from any one or more DC interfaces can be fed to the AC interface; energy only needs to flow through one functional group and another shared functional group to complete the conversion, reducing the number of power conversion stages compared to traditional architectures. In DC-DC mode, power can be directly transferred between any two DC interfaces, i.e., energy is directly transferred between DC interfaces through their respective first / third functional groups, avoiding the multi-stage DC-AC-DC conversion required in traditional architectures. This embodiment reduces the number of core power units and optimizes the system structure through functional group multiplexing. Simultaneously, due to the shortened energy transmission path and reduced conversion times, the overall energy transmission efficiency is significantly improved.

[0082] In this embodiment, the power units are all built with switching transistors. By controlling each switching transistor in the power unit to perform the corresponding switching action (conduction or deactivation), the direction of energy transmission can be switched, such as realizing bidirectional energy flow between any DC interface and AC interface, or realizing bidirectional energy flow between multiple DC interfaces.

[0083] This embodiment significantly reduces the hardware cost required for adding new DC interfaces through the sharing mechanism of the second functional group, avoids redundant configuration of functional units, optimizes the energy transmission path, eliminates the need for multi-stage AC-DC-AC conversion during energy transmission between DC interfaces, reduces the number of power conversions, improves the overall system efficiency, provides high architectural flexibility, can adapt to different application requirements through different functional group division methods, supports bidirectional energy flow of multiple interfaces, and enhances the application scope and practicality of the system.

[0084] Based on the above embodiments:

[0085] In an exemplary embodiment, the first functional group and the second functional group are arranged sequentially according to the energy flow direction from the first DC interface to the AC interface.

[0086] In this embodiment, in application scenarios such as photovoltaic power generation grid-connected systems and energy storage systems feeding power to the grid, energy mainly flows from the DC side to the AC side. In this configuration, the first functional group is closer to the DC side and is primarily responsible for power processing and conversion at the DC end. This includes, for example, a DC-side filtering unit, a DC-DC conversion unit (DC-side power unit), and may even include an AC-side power unit for AC-DC or DC-AC conversion, depending on the division method. The second functional group is closer to the AC interface, and its core function is to standardize the electrical energy ultimately fed into the AC interface. This includes, for example, at least an AC-side filtering unit, ensuring that the output electrical energy meets grid connection or load requirements. Under this architecture, regardless of which DC interface the electrical energy comes from, it undergoes final processing via the same second functional group (especially the filtering unit) before being fed into the grid or supplied to the AC load. This ensures a high degree of consistency in the power quality (such as harmonic content and electromagnetic interference levels) output from all interfaces, simplifying the complexity of grid connection certification and system testing. Furthermore, AC-side filtering units (such as LCL filters) typically contain bulky and costly magnetic components (inductors). By reusing this unit, each new DC interface no longer requires a separate, costly AC filter circuit, thus reducing costs during system expansion, avoiding the duplication of multiple bulky filters, significantly saving internal system space, facilitating higher power density, and making the equipment more compact. At the same time, this centralized filtering design also improves system reliability and reduces maintenance complexity.

[0087] It should be noted that although this embodiment mainly illustrates the functional group configuration order with energy flow from DC to AC, it is understood that by adjusting the control strategy, this architecture can also support reverse energy flow, i.e., energy transfer from the AC interface to the DC interface. Furthermore, as mentioned above, the functional group configuration order can also be adjusted according to actual application requirements, including but not limited to configuring them in order from the AC interface to the DC interface. For example, in systems primarily powered by the power grid, the AC-side processing unit can be preferentially configured as the first functional group. This flexible configuration allows the conversion circuit of this invention to adapt to diverse application scenarios and system architecture requirements.

[0088] Reference Figure 4 As shown, the first energy transmission module may include a DC-side filter unit, a DC-side power unit, a capacitive inductor unit, a transformer unit, an AC-side power unit, and an AC-side filter unit connected in sequence. The DC-side filter unit is connected to a DC interface, and the AC-side filter unit is connected to an AC interface. (Refer to...) Figure 5As shown, the DC-side filter unit includes at least two capacitors (C1 and C2) and one inductor (L1), the DC-side power unit includes at least four switching transistors (Q1, Q2, Q3, Q4), the transformer unit includes at least one transformer (T1), the capacitive-inductor unit includes at least one inductor (L2), the AC-side power unit includes at least four switching transistors (Q5, Q6, Q7, Q8) and two capacitors (C3, C4), and the AC-side filter unit includes at least one inductor (L3) and one capacitor (C5).

[0089] Specifically, the DC-side filter unit can be used to stabilize the DC-side voltage, suppress current ripple and electromagnetic interference (MEI), and capacitors C1 and C2 mainly serve to stabilize the voltage and filter out high-frequency noise, providing a low-impedance voltage source for the subsequent switching transistors. Inductor L1, together with the capacitors, forms an LC filter network to smooth the current from the DC interface and prevent high-frequency noise generated by the switching transistors from propagating back to the DC power supply side.

[0090] The DC-side power unit is used for power conversion and control on the DC side to achieve DC-DC conversion. These four switching transistors (usually MOSFETs or IGBTs) form a full-bridge topology. By controlling them to alternately turn on and off in a specific sequence and frequency, the input DC power is converted into a high-frequency AC square wave. This high-frequency square wave is a prerequisite for subsequent efficient energy transfer through the transformer. When working in reverse (energy flows from AC to DC), this unit is responsible for rectifying the high-frequency AC power from the transformer into DC power.

[0091] The capacitive inductor unit can be used in conjunction with the transformer leakage inductance to form a resonant network, enabling soft switching. Inductor L2 acts as a resonant inductor in this case. It, along with the leakage inductance of transformer T1 and the parasitic capacitances in the circuit (mainly the junction capacitance of the switching transistor), constitute an LLC resonant network (or a similar resonant topology). The resonance process allows the current or voltage flowing through the switching transistor to naturally cross zero at the moment of switching action, thereby achieving zero-voltage switching (ZVS) or zero-current switching (ZCS). This reduces switching losses and noise, and improves system efficiency and electromagnetic compatibility (EMI) performance.

[0092] The transformer unit is used to achieve electrical isolation and voltage transformation. There is no direct electrical connection between the primary and secondary sides of transformer T1, ensuring safe isolation between the DC and AC sides. At the same time, by adjusting the turns ratio of the primary and secondary windings, the voltage can be flexibly increased or decreased to meet different voltage level requirements. The high-frequency AC square wave energy generated by the DC power unit is transferred to the secondary side through magnetic coupling.

[0093] The AC-side power unit is used for power conversion on the AC side, realizing DC-AC inversion or AC-DC rectification. When energy flows from DC to AC (inverter mode), the four switching transistors in the AC-side power unit modulate the high-frequency AC power from the secondary side of the transformer into a sinusoidal AC power at the power frequency. Capacitors C3 and C4 serve to support voltage and filter the signal. When energy flows from AC to DC (rectification mode), this unit converts the power frequency AC power into high-frequency AC power for transmission to the primary side via the transformer.

[0094] The AC side filter unit is used to filter out high-frequency switching harmonics and output high-quality sinusoidal current. Inductor L3 and capacitor C5 form an L-type or LC-type low-pass filter to filter out the high-frequency PWM carrier component generated by the switching action of the AC side power unit, ensuring that the current finally injected into the grid or supplied to the load is a smooth and pure sinusoidal wave, meeting the requirements of grid-connected power quality standards.

[0095] by Figure 4 and Figure 5 Taking the first energy transmission module as an example, the optional division methods of the first functional group and the second functional group are explained in detail.

[0096] The first division method: The DC-side filter unit, DC-side power unit, transformer unit, capacitive inductor unit, and AC-side power unit, connected in sequence, are divided into the first functional group; the AC-side filter unit is divided into the second functional group; correspondingly, the third functional group also includes the DC-side filter unit, DC-side power unit, transformer unit, capacitive inductor unit, and AC-side power unit connected in sequence. The extension node is located between the AC-side power unit and the AC-side filter unit, as shown in the reference. Figure 6 , Figure 7 As shown, Figure 6 and Figure 7 In this architecture, DC1 is the first DC interface, and DC2...DCN are all second DC interfaces. All DC interfaces share the AC-side filter unit. This partitioning method treats the AC-side filter unit as a shared resource, eliminating the need for a separate AC filter circuit for each newly added DC port. This approach reduces the number of components and cost during system expansion, while also helping to maintain consistent power quality across all ports.

[0097] The second division method: The DC-side filter unit, DC-side power unit, transformer unit, and capacitive inductor unit, connected in sequence, are divided into the first functional group; the AC-side power unit and AC-side filter unit, connected in sequence, are divided into the second functional group. Correspondingly, the third functional group also includes the DC-side filter unit, DC-side power unit, transformer unit, and capacitive inductor unit, connected in sequence. The extension node is located between the capacitive inductor unit and the AC-side power unit, as shown in the reference. Figure 8 , Figure 9 As shown. Figure 8, Figure 9 In this architecture, DC1 is the first DC interface, and DC2...DCN are all second DC interfaces. All DC interfaces share the AC-side power unit and the AC-side filter unit. This approach reduces system cost while maintaining the independence of each port from the DC-side isolation conversion section by sharing the AC-side power unit and filter unit. This allows the system to adapt to DC sources with different characteristics, such as batteries and photovoltaic modules.

[0098] The third partitioning method: The DC-side filter unit, DC-side power unit, and transformer unit, connected in sequence, are divided into the first functional group; the capacitive inductor unit, AC-side power unit, and AC-side filter unit, connected in sequence, are divided into the second functional group; and correspondingly, the third functional group also includes the DC-side filter unit, DC-side power unit, and transformer unit, connected in sequence. The extension node is located between the transformer unit and the capacitive inductor unit. In this architecture, all DC interfaces share the capacitive inductor unit, AC-side power unit, and AC-side filter unit. Including the capacitive inductor unit and AC-side unit in the shared portion unifies the system's resonant network, simplifies resonant parameter design, reduces performance inconsistencies caused by differences in parameters of multiple independent resonant units, and positively impacts the overall system efficiency.

[0099] The fourth partitioning method: The sequentially connected DC-side filter unit and DC-side power unit are divided into the first functional group; the sequentially connected transformer unit, capacitive inductor unit, AC-side power unit, and AC-side filter unit are divided into the second functional group; correspondingly, the third functional group also includes the sequentially connected DC-side filter unit and DC-side power unit. The expansion node is located between the DC-side power unit and the transformer unit. In this architecture, all DC interfaces share the transformer unit, capacitive inductor unit, AC-side power unit, and AC-side filter unit. This partitioning achieves sharing of the transformer and all subsequent functional units, resulting in high system integration. New ports only require the upstream DC-DC converter unit, significantly reducing the overall complexity and cost of the multi-port system, and is suitable for applications with similar DC source voltage levels.

[0100] To avoid the lack of a capacitive inductor unit when the transformer unit is connected to the energy conversion between multiple DC ports, this embodiment adjusts the position of the capacitive inductor unit between the DC-side power unit and the transformer unit. This results in a fifth division method: the sequentially connected DC-side filter unit, DC-side power unit, and capacitive inductor unit are divided into a first functional group; the sequentially connected transformer unit, AC-side power unit, and AC-side filter unit are divided into a second functional group; correspondingly, the third functional group also includes the sequentially connected DC-side filter unit, DC-side power unit, and capacitive inductor unit, with the expansion node located between the capacitive inductor unit and the transformer unit, as shown in the reference. Figure 10 and Figure 11 As shown. Figure 10 and Figure 11 In this architecture, DC1 is the first DC interface, and DC2...DCN are all second DC interfaces. All DC interfaces share the transformer unit, AC-side power unit, and AC-side filter unit. By adjusting the capacitive inductor unit to the first functional group, each DC port has an independent resonant conversion link. This division supports efficient direct energy exchange between DC ports and reduces costs by sharing the transformer and AC-side units, making it suitable for systems with frequent inter-port energy dispatching.

[0101] In an exemplary embodiment, the first functional group or the second functional group further includes a transformer unit, and the first functional group and / or the second functional group further includes at least one capacitive inductor unit, the capacitive inductor unit including a first inductor and a first capacitor, wherein:

[0102] The first end of the first inductor is connected to the transformer unit, and the second end of the first inductor is connected to the first capacitor.

[0103] In this embodiment, since there are different ways to divide the multiple functional units connected sequentially in the first energy transmission module, there are cases where the first functional group includes one capacitive inductor unit and the second functional group includes one capacitive inductor unit; cases where the first functional group includes two capacitive inductor units and the second functional group does not include any capacitive inductor units; and cases where the first functional group does not include any capacitive inductor units and the second functional group includes two capacitive inductor units. That is, at least one capacitive inductor unit can be set on the energy transmission path in this embodiment. In this embodiment, the capacitive inductor unit includes a first capacitor (Cs) in addition to the first inductor (L2), forming an inductor-capacitor series structure. It can be understood that the first capacitor and the first inductor together constitute a defined series resonant cavity, which can work in conjunction with other reactive components in the circuit (such as transformer leakage inductance). Through resonant operation, the switching transistor can complete the switching under zero-voltage switching or zero-current switching conditions, thereby systematically reducing switching losses and electromagnetic interference and improving conversion efficiency.

[0104] When setting up a capacitive inductor unit, it can be placed on the primary side of the transformer unit, such as... Figure 12 As shown, implementing soft switching of the primary-side switching transistors (such as Q1-Q4) directly improves the efficiency and reliability of the primary-side power unit while maintaining the simplicity of the secondary-side circuit; alternatively, the capacitive inductor unit can be placed on the secondary side of the transformer unit, such as... Figure 13 As shown, placing the resonant network on the secondary side can create soft-switching conditions for the AC / DC conversion stage. At the same time, this LC structure can also play a certain filtering role, which helps to improve the output current waveform.

[0105] When setting up multiple capacitive inductor units, capacitive inductor units can be set on both the primary and secondary sides of the transformer unit, such as... Figure 14As shown, the primary side of the transformer unit is equipped with the first capacitive inductor unit (including Cp and Lp), and the secondary side of the transformer unit is equipped with the second capacitive inductor unit (including L2 and Cs). By setting independent resonant networks on the primary and secondary sides respectively, the optimal soft-switching conditions can be created for the power switching transistors on both sides more flexibly and accurately, thereby improving the degree of freedom in optimizing the overall system efficiency and enabling efficient operation over a wider load range.

[0106] In an exemplary embodiment, when the capacitive inductor is disposed on the secondary side of the transformer unit, the capacitive inductor further includes a second inductor, which is connected in parallel with the secondary winding of the transformer unit.

[0107] In this embodiment, the second inductor (Lm) serves as a parallel magnetizing inductor, forming an LCL or LLC type resonant network together with the first inductor and the first capacitor connected in series. (See attached diagram.) Figure 15 When Lm and Cs are added simultaneously to the capacitive inductance unit on the secondary side of the transformer unit, an LLC resonant network can be formed. Lm can utilize the excitation inductance of the transformer itself. This network can achieve zero-voltage switching (ZVS) of the switching transistor and zero-current switching (ZCS) of the secondary rectifier transistor over a wide load range, significantly reducing switching losses.

[0108] In one exemplary embodiment, reference is made to Figure 16 As shown, the power unit includes multiple switching transistors, and the conversion circuit also includes:

[0109] The detection unit is used to detect the electrical operating parameters of the conversion circuit;

[0110] The control unit is used to control the corresponding switching transistor to perform switching actions according to electrical operating parameters, so as to transfer energy between the AC interface and any DC interface, or between multiple DC interfaces.

[0111] In this embodiment, the electrical operating parameters include, but are not limited to, the voltage and current of the DC interface, the voltage and current of the AC interface, the primary and secondary electrical parameters of the transformer unit, and the operating status parameters of each power unit. (Refer to...) Figure 17 As shown, the detection unit includes multiple input ports, which are used to connect to the electrical operating parameters of the energy transmission path corresponding to each DC interface. By sampling and processing these parameters in real time, the accurate operating status of the conversion circuit is obtained, and then the detection unit processes and sends it to the control unit. The control unit adds a multi-channel control function, that is, it has the ability to generate multiple independent PWM signals. The multiple control ports of the control unit are used to connect to the power units on the energy transmission path corresponding to each DC interface, realizing independent control and coordinated management of each port.

[0112] As an example, in an integrated photovoltaic-storage-charging system, the detection unit simultaneously monitors the output power of the photovoltaic array, the charge / discharge status of the battery, the voltage level of the supercapacitor, and the operating condition of the AC grid. Based on this data, the control unit can perform the following controls: during the day when photovoltaic power generation is sufficient, it controls the corresponding switching transistors to supply part of the photovoltaic energy to the AC load and part to charge the battery; during peak electricity consumption, it controls the battery energy to feed into the grid; when an electric vehicle is connected, it coordinates the battery and the grid to charge the vehicle together; in the event of a grid failure, it switches to off-grid operation mode, with the photovoltaic system and battery ensuring power supply to the local load.

[0113] This detection and control architecture, combined with the aforementioned circuit topology, enables intelligent energy scheduling and flexible switching between multiple modes. Through precise real-time control, it ensures that soft-switching technology can be effectively implemented in various operating modes, further improving the overall system efficiency. The independent port control capability allows the system to manage DC sources with different characteristics simultaneously and fully leverages the advantages of functional group multiplexing in the aforementioned circuit topology, enhancing the system's reliability and safety. Real-time monitoring of various electrical parameters enables rapid fault diagnosis and protection.

[0114] In summary, this invention provides a multi-port, single-stage, bidirectional isolated AC-CDC converter architecture. The single-stage, bidirectional isolated AC-CDC converter architecture includes a DC-side filter unit, a DC-side power unit, a transformer unit, a capacitive inductor unit, an AC-side power unit, an AC-side filter unit, a detection unit, and a control unit. This invention achieves a multi-port, single-stage, bidirectional isolated AC-CDC converter architecture by expanding the number of branches in the transformer unit, capacitive inductor unit, or AC-side power unit; adding multi-channel detection functionality to the detection unit; and adding multi-channel control functionality to the control unit. The single-stage power conversion is low-cost and highly efficient.

[0115] Furthermore, based on the above circuit structure, considering that the control system of the conversion circuit (including the detection unit and control unit mentioned above) generally has a certain sampling and control delay, distorted transient reverse voltage of the power grid can cause a short circuit risk in the bridge arm of the AC side power unit of the conversion circuit. In related technologies, such as... Figure 18 As shown, a voltage threshold Vth is typically set. When the AC voltage Vac is less than Vth, the four switching transistors (Q5, Q6, Q7, Q8) of the AC side power unit are controlled by a set of complementary drive signals, such as... Figure 19 As shown in Table 1. Specifically, Q5 and Q6 are defined as one switch group, and Q7 and Q8 are defined as another switch group. In the complementary drive mode, Q5 and Q6 are driven synchronously (i.e., they are turned on or off simultaneously), Q7 and Q8 are driven synchronously, and the drive signals of the two switch groups are complementary (i.e., when Q5 and Q6 are on, Q7 and Q8 are off, and vice versa). Their switching actions are shown in Table 1.

[0116] Table 1 Switching Action Table of Switching Transistors in AC Side Power Unit

[0117]

[0118] By forcing the upper and lower switch groups of the same bridge arm to not conduct simultaneously, the risk of bridge arm shoot-through short circuits caused by control system delays or voltage distortions is fundamentally avoided. However, since Q5 and Q6 always operate synchronously, and Q7 and Q8 also always operate synchronously, the switching transistors lose the independent switching sequence necessary to achieve soft switching (such as zero-voltage switching, ZVS), causing all switching transistors to operate in hard-switching mode. When the absolute value of the AC voltage Vac is lower than the set Vth threshold, the control system forces all switching transistors of the AC side power unit into a complementary-driven hard-switching mode to absolutely avoid the risk of bridge arm shoot-through. If Vth is set too low, its protection range (i.e., the hard-switching operating area) is very narrow. When a momentary overshoot or distortion occurs in the power grid, causing the instantaneous value of Vac to exceed this narrow Vth range, the control system will erroneously exit the protective hard-switching mode. At this time, if a control delay exists, the risk of bridge arm shoot-through short circuits will increase significantly. If Vth is set too high, it means that the conversion circuit operates in hard-switching mode for most of its operating time (as long as the absolute value of Vac is less than this large Vth). Hard switching generates significant switching losses, leading to a decrease in overall system efficiency. It also increases the temperature of the power switching transistors and heatsinks, increasing thermal stress and reducing reliability.

[0119] Based on this, this application also provides a control method for a conversion circuit, wherein the conversion circuit is the conversion circuit described in any of the embodiments above, the conversion circuit includes an AC side power unit, the AC side power unit includes at least one bridge arm, the bridge arm includes two switch groups, and the two switches in the switch groups are respectively located in the upper bridge arm and the lower bridge arm of the bridge arm, and the control method for the conversion circuit includes:

[0120] A first complementary drive signal is output to one switch group, and a second complementary drive signal is output to another switch group after a delay between the delay groups.

[0121] The first complementary drive signal and the second complementary drive signal are both used to control one of the switches in the corresponding switch group to perform a disconnection action, and after a dead time delay, control the other switch to perform a conduction action. The dead time is less than the inter-group delay time.

[0122] In this embodiment, the AC-side power unit includes at least one bridge arm. The following description uses one bridge arm as an example; the other bridge arms are described similarly. Each bridge arm includes two switch groups, and each switch group includes two switching transistors. The two switching transistors in each switch group are located in the upper and lower bridge arms of that bridge arm, respectively. (Refer to...) Figure 5As shown, the bridge arm includes four switching transistors, namely Q5, Q6, Q7, and Q8. Q5, Q6, Q7, and Q8 are connected in series between the positive and negative terminals of the busbar. In this embodiment, the first switching group is Q5 and Q7, and the second switching group is Q6 and Q8. Unlike the vertical grouping in related technologies, this embodiment divides the four switching transistors on the bridge arm into two complementary groups. That is, the two switching transistors in each switching group in this embodiment will not be turned on at the same time.

[0123] Specifically, in this embodiment, a first complementary drive signal is output to one of the switch groups on the bridge arm. The first complementary drive signal is a set of complementary drive signals used to control two switches in the switch group to perform complementary switching actions respectively. Specifically, the first complementary drive signal first controls the switch in the switch group that is currently in the on state to perform an off action, and then, after a dead time delay, controls the other switch in the switch group to perform an on action.

[0124] After outputting the first complementary drive signal to the first switch group, a delay of one inter-group delay time is applied before outputting the second complementary drive signal to the other switch group. The second complementary drive signal is also a set of complementary drive signals, used to control two switches in the other switch group to perform complementary switching actions. Its control logic is the same as that of the first complementary drive signal: first, disconnect the currently conducting switch, delay the dead time, and then turn on the other switch in the same group.

[0125] Dead time refers to the waiting time within the same switching group after one switch is turned off, before another switch is turned on. This delay ensures that no common circuit occurs within the switching group, preventing the simultaneous turn-on of two switches due to overlapping off and on signals, thus preventing short circuits within the switching group. During the dead time, both switches in the same switching group are in the off state. At this time, parasitic inductance in the circuit (such as transformer leakage inductance or wiring inductance) maintains the current flow. This current charges and discharges the junction capacitance of the switches. Specifically, it removes the charge from the junction capacitance of the switch about to be turned on, creating a zero-voltage turn-on condition for it.

[0126] In this embodiment, the inter-group delay time is greater than the dead time, so that the second switch group is controlled only after the first switch group has switched to the new state and stabilized, thereby avoiding the control of the second switch group during the dead time of the first switch group. It is understandable that when the second switching group enters the dead time, two switches in the second switching group are off, while one switch in the first switching group is on and one is off. At this time, three of the four switches in this bridge arm are off, and one is on. Since the switches in the first switching group are on, and the two switches in the second group are off, the freewheeling current maintained by the inductance (leakage inductance of the transformer, etc.) in the circuit is forced to flow through the on-circuit switch in the first switching group, and then charge and discharge the junction capacitance of the two switches in the second switching group. Depending on the circuit's operating state, this charging and discharging process will produce two possible soft-switching conditions. When the resonant process resonates the voltage across the switch that is about to be turned on to zero, the switch is turned on after the dead time of the second group, thus achieving zero-voltage switching (ZVS). Under certain operating states, the freewheeling current will naturally cross zero during the dead time, so that when the switch is turned on after the dead time of the second group, the current starts from zero, thus achieving zero-current switching (ZCS).

[0127] It is understandable that by using two sets of complementary drive signals to control the four switches in the bridge arm to perform complementary switching actions, the four switches will not conduct simultaneously at the same time, thus reliably avoiding the risk of bridge arm short circuits caused by distorted transient reverse voltage of the power grid. Moreover, a certain delay is added between the two sets of complementary drive signals. By setting the inter-set delay time to be greater than the dead time, the conditions for the switches to achieve zero-voltage switching / zero-current switching are created while ensuring safety, enabling soft switching and improving efficiency.

[0128] In one exemplary embodiment, the control method for the conversion circuit further includes:

[0129] Obtain the AC side voltage of the conversion circuit;

[0130] Based on the polarity of the AC side voltage, determine the leading and lagging groups in the two switching groups;

[0131] The process of outputting a first complementary drive signal to one switch group and, after a delay between switch groups, outputting a second complementary drive signal to another switch group includes:

[0132] The first complementary drive signal is output to the leading group, and the second complementary drive signal is output to the lagging group after the inter-group delay time.

[0133] In this embodiment, the leading group refers to the switching group that receives the drive signal and performs the switching action first in each switching cycle, while the lagging group refers to the switching group that receives the drive signal and performs the switching action after a delay between groups. The division of labor between the two groups is dynamically adjusted according to the polarity of the AC side voltage to ensure optimal soft-switching effect. First, the AC side voltage Vac of the conversion circuit is obtained, and then the polarity of the AC side voltage Vac is determined, that is, whether Vac is positive or negative. When Vac is positive or negative, the leading and lagging groups in the two switching groups are different. Specifically, when Vac is positive, the first switching group (Q5, Q7) is determined as the leading group, and the second switching group (Q6, Q8) is determined as the lagging group. When Vac is negative, the first switching group (Q5, Q7) is determined as the lagging group, and the second switching group (Q6, Q8) is determined as the leading group.

[0134] This mechanism of dynamically allocating the leading and lagging groups based on voltage polarity ensures that the switching group subjected to higher voltage stress can obtain optimal soft-switching conditions in any half-cycle, thereby optimizing overall efficiency throughout the entire cycle. In this embodiment, the leading group switches are first controlled to perform their corresponding switching actions. Then, after a delay between groups, the lagging group switches are controlled to perform their corresponding switching actions. Through this adaptive allocation strategy, the system can automatically optimize the switching sequence according to actual operating conditions, creating optimal soft-switching opportunities for switches with different polarities.

[0135] As a specific example, during the positive half-cycle of Vac, a first complementary drive signal is first output to the first switch group (Q5, Q7) of the leading group to control its switching action; after the inter-group delay time, a second complementary drive signal is then output to the second switch group (Q6, Q8) of the lagging group, as follows: Figure 20 As shown. During the negative half-cycle of Vac, the drive signal is first output to the second switch group (Q6, Q8) which is the leading group. After the inter-group delay time, the drive signal is then output to the first switch group (Q5, Q7) which is the lagging group, as shown. Figure 21 As shown.

[0136] In one exemplary embodiment, the control method for the conversion circuit further includes:

[0137] When the AC side voltage is greater than the absolute value of the preset threshold corresponding to the polarity, a target drive signal is output to the leading group and a second complementary drive signal is output to the lagging group. The target drive signal is used to control the two switches in the leading group to maintain the conducting state.

[0138] The process of outputting a first complementary drive signal to the leading group and, after a delay between the delay groups, outputting a second complementary drive signal to the lagging group includes:

[0139] When the AC side voltage is less than or equal to the absolute value of the preset threshold corresponding to the polarity, the first complementary drive signal is output to the leading group, and after the delay time between the delay groups, the second complementary drive signal is output to the lagging group.

[0140] In this embodiment, to further reduce the switching losses of the lead group, two preset thresholds are set for the polarity of the AC side voltage, namely... Figure 22 The positive and negative threshold voltages in the settings, with the absolute values ​​of the preset thresholds including both positive and negative threshold voltages, correspond to the protection intervals of the positive and negative half-cycles of the AC side voltage, respectively. The target drive signal is a special drive signal that keeps two switching transistors in the switching group conducting simultaneously; this operating mode is called the normally-on mode. The first and second complementary drive signals are complementary drive signals with dead time, used to achieve high-frequency switching action for soft switching.

[0141] In this embodiment, the operating mode can be dynamically adjusted according to the amplitude of the AC side voltage. A hybrid mode of normally-on and high-frequency switching is used in regions with large voltage amplitudes, while a full-frequency soft-switching mode is used near the voltage zero-crossing region, thereby achieving efficiency optimization across the entire cycle. Specifically, when the polarity is positive and the AC side voltage is greater than the positive threshold voltage, the two switches in the leading group are controlled to be normally open (i.e., normally conducting), and the two switches in the lagging group are controlled to perform high-frequency operations, such as... Figure 23 As shown, when the AC side voltage is less than or equal to the positive threshold voltage, the two switches in the lead group and the two switches in the lag group execute their respective high-frequency switching actions, i.e., complementary switching actions with dead time. This design allows the lead group, which bears greater voltage stress at higher voltages, to avoid high-frequency switching losses, while the lag group undertakes the main power regulation function.

[0142] As a concrete example, consider a 230V AC system with a positive threshold voltage of 50V. During the positive half-cycle, when the voltage rises from zero and does not exceed 50V, the system adopts a full-frequency soft-switching mode; when the voltage exceeds 50V, the lead group switches to a normally-on mode, and only the lagging group performs high-frequency switching operation; when the voltage drops from its peak and reaches 50V again, the system switches back to the full-frequency soft-switching mode. The operating logic of the negative half-cycle is symmetrical, but uses a negative threshold voltage of -50V as the mode switching point.

[0143] When the polarity is negative and the AC side voltage is less than the negative threshold voltage, the two switches in the lead group are normally open (i.e., normally conducting). When the AC side voltage is greater than or equal to the negative threshold voltage, the two switches in the lead group and the two switches in the lag group respectively execute their corresponding high-frequency switching actions, i.e., complementary switching actions with dead time, such as... Figure 24As shown in the diagram, this symmetrical control strategy ensures that the system achieves optimal performance in both the positive and negative half-cycles.

[0144] This embodiment introduces a hybrid control mode based on voltage amplitude, which significantly reduces the number of switching operations in the peak region of AC voltage, thereby reducing the total switching loss of the system. By reasonably setting the threshold voltage, the system efficiency is maximized while ensuring waveform quality. This hybrid control strategy complements the aforementioned soft-switching technology, adopting the most suitable control method in different operating ranges to achieve optimal efficiency across the entire operating range, reducing the thermal stress on power devices, and still using precise high-frequency control in the voltage zero-crossing region to ensure waveform quality.

[0145] In an exemplary embodiment, the difference between the inter-group delay time and the dead time is greater than the turn-on delay time of the switching transistor.

[0146] In this embodiment, the turn-on delay time includes the turn-on delay time Td(on) and rise time Tr of the switching transistor. This is the physical response time required for the power switching device to fully turn on from receiving the drive signal. That is, the switching transistor does not immediately perform the switching action when the drive signal is issued. For example, if the controller issues a signal to turn on switch B at time t1, but due to the delay in switch B, it will take longer to turn on. Since the connection is only truly established at a certain moment, this embodiment stipulates that the difference between the inter-group delay time Tdelay and the dead time Tdead must meet specific conditions: This ensures that zero voltage or zero current conditions are met when the switching transistor performs the switching action, thereby improving the reliability of soft switching and the stability and efficiency of the system across the entire operating range.

[0147] In summary, combining Figure 23 The complete control process of four switching transistors on one bridge arm is explained.

[0148] Reference for operating current loop at times t1~t3 Figure 25 As shown, Q8 ZVS is off at time t1, and Q6 ZCS is on at time t2. The operating current loop at times t3~t4 is referenced. Figure 26 As shown, Q7 is disconnected at time t3. The operating current loop at times t4~t5 is referenced. Figure 27 As shown, Q5 ZVS is turned on at time t4. The operating current loop from t5 to t7 is referenced. Figure 28 As shown, at time t5, Q6 ZVS is off, and at time t6, Q8 ZCS is on. The operating current loop at times t7~t8 is referenced. Figure 29 As shown, Q5 is hard-switched off at time t7, and the operating current loop at times t8~t9 is referenced. Figure 30As shown, Q7 ZVS is turned on at time t8. Refer to Table 2 for an explanation of the switching modes of the switching transistors.

[0149] Table 2 Switching Modes of Switching Transistors

[0150]

[0151] In summary, this application reliably avoids the risk of bridge arm short circuits caused by distorted grid transient reverse voltage by controlling the complementary switching of power switching devices within the bridge arm through two sets of complementary conduction control signals; a certain delay can be applied between the two sets of complementary conduction control signals to achieve soft switching and improve efficiency; at the same time, a threshold voltage can be set, and when the grid voltage exceeds the threshold voltage, the normally open lead group of the two sets of complementary conduction control signals is controlled to reduce the switching losses of the lead group power switching devices and further improve system efficiency.

[0152] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0153] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A conversion circuit, characterized by, The application relates to a conversion circuit. The conversion circuit comprises: an alternating current (AC) interface; a plurality of direct current (DC) interfaces, including a first DC interface and a second DC interface; a first energy transmission module arranged between the first DC interface and the AC interface, the first energy transmission module comprising a first functional group and a second functional group connected in series; a second energy transmission module arranged between the second DC interface and an extension node of the first energy transmission module, the extension node being located at a connection between the first functional group and the second functional group, the second energy transmission module comprising a third functional group configured to have the same circuit function as the first functional group; 2. The conversion circuit of claim 1, wherein wherein the first functional group and / or the second functional group comprises at least one power unit for performing a power conversion operation.

3. The conversion circuit of claim 1, wherein The first functional group and the second functional group are arranged in sequence in the direction of energy flow from the first DC interface to the AC interface.

4. The conversion circuit of claim 1, wherein The first functional group and the third functional group each comprise a DC side filter unit, a DC side power unit, a capacitance and inductance unit and a transformer unit connected in sequence, the second functional group comprises an AC side power unit and an AC side filter unit connected in sequence, and the extension node is arranged between the transformer unit and the AC side power unit; the power unit comprises the AC side power unit and the DC side power unit. The first functional group or the second functional group further comprises a transformer unit, and the first functional group and / or the second functional group further comprises at least one capacitance and inductance unit, the capacitance and inductance unit comprising a first inductor and a first capacitor, wherein:

5. The conversion circuit of claim 4, wherein, a first end of the first inductor is connected to the transformer unit, and a second end of the first inductor is connected to the first capacitor.

6. The conversion circuit of claim 1, wherein When the capacitance and inductance unit is arranged on the secondary side of the transformer unit, the capacitance and inductance unit further comprises a second inductor, and the second inductor is connected in parallel to the secondary winding of the transformer unit.

7. The conversion circuit according to any one of claims 1 to 6, characterized by The number of the second DC interfaces and the number of the second energy transmission modules are both plural, and the plurality of second energy transmission modules are arranged one-to-one between the plurality of second DC interfaces and the extension node. The power unit comprises a plurality of switch tubes, and the conversion circuit further comprises: a detection unit for detecting an electrical operating parameter of the conversion circuit; 8. A control method of a conversion circuit, characterized by, a control unit for controlling the switch tubes to perform switching actions according to the electrical operating parameter, so as to enable energy transmission between the AC interface and any DC interface or between the plurality of DC interfaces. The conversion circuit is the conversion circuit according to any one of claims 1-7, the conversion circuit comprises an AC side power unit, the AC side power unit comprises at least one bridge arm, the bridge arm comprises two switch groups, two switch tubes in the switch groups are located on upper and lower bridge arms of the bridge arm respectively, and the control method of the conversion circuit comprises: outputting a first complementary driving signal to one switch group, and outputting a second complementary driving signal to another switch group after a delay time between the groups. The first complementary drive signal and the second complementary drive signal are used to control one switch tube in the corresponding switch group to perform the off action, delay a dead time, and then control the other switch tube to perform the on action, and the dead time is less than the inter-group delay time.

9. The control method of a conversion circuit according to claim 8, characterized by, The control method of the conversion circuit further includes: obtaining an alternating current side voltage of the conversion circuit; determining a leading group and a lagging group in the two switch groups according to a polarity of the alternating current side voltage; the process of outputting the first complementary drive signal to one switch group and outputting the second complementary drive signal to the other switch group after delaying the inter-group delay time includes: outputting the first complementary drive signal to the leading group and outputting the second complementary drive signal to the lagging group after delaying the inter-group delay time.

10. The control method of a conversion circuit according to claim 9, characterized by, The control method of the conversion circuit further includes: when the alternating current side voltage is greater than an absolute value of a preset threshold corresponding to the polarity, outputting a target drive signal to the leading group and outputting the second complementary drive signal to the lagging group, the target drive signal being used to control two switches in the leading group to maintain the on state; the process of outputting the first complementary drive signal to the leading group and outputting the second complementary drive signal to the lagging group after delaying the inter-group delay time includes: when the alternating current side voltage is less than or equal to the absolute value of the preset threshold corresponding to the polarity, outputting the first complementary drive signal to the leading group and outputting the second complementary drive signal to the lagging group after delaying the inter-group delay time.

11. The control method of a conversion circuit according to any one of claims 8 to 10, characterized by, The difference between the inter-group delay time and the dead time is greater than a turn-on delay time of the switch tube.

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