Dual-active bridge series-parallel connection switching control device and method

Abstract

The invention relates to the technical field of converters, and discloses a dual-active-bridge series-parallel switching control device and method, and the method comprises the steps: enabling a negative electrode output end of a front-stage dual-active bridge to be connected with a positive electrode output end of a rear-stage dual-active bridge through a series relay; a first parallel relay connects the positive electrode output end of any one of the other dual-active bridges except the first-stage dual-active bridge with the positive electrode output end of the first-stage dual-active bridge; one second parallel relay is used for connecting the negative electrode output end of any other dual-active bridge except the first-stage dual-active bridge with the negative electrode output end of the first-stage dual-active bridge; the anode output end of the first-stage dual-active bridge is connected with the anode power supply end of the load, and the cathode output end of the last-stage dual-active bridge is connected with the cathode power supply end of the load. According to the invention, the relay self-inspection is introduced, so that whether the relay has a fault can be judged, and serial-parallel non-impact current smooth switching can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and particularly to a control device and method for series-parallel switching of dual active bridges in series and parallel. Background Art

[0002] Dual Active Bridge (DAB for short) DC-DC converters have been widely used in fields such as DC microgrids, green transportation energy systems, rail transit energy systems, and electric vehicle charging because they can achieve bidirectional isolation transmission of power on the input and output sides, and have advantages such as high power density and operation in a wide voltage range.

[0003] The output voltage range of the dual active bridge is limited. In actual application scenarios, in order to achieve a wider output voltage range and a higher power level, multiple modules need to be switched in series and parallel. However, in related technologies, the series-parallel switching control of the power supply is only applicable to converters in a small power range, and does not involve the smooth switching of series-parallel of dual active bridges with wide voltage output and high power without inrush current. Summary of the Invention

[0004] In view of this, the present invention provides a control device and method for series-parallel switching of dual active bridges to solve the problem of how to achieve series-parallel switching control of dual active bridges.

[0005] In a first aspect, the present invention provides a control device for series-parallel switching of dual active bridges, including: at least one series relay, at least one first parallel relay, and at least one second parallel relay, wherein, one series relay is used to connect the negative output terminal of the front-stage dual active bridge to the positive output terminal of the rear-stage dual active bridge; one first parallel relay is used to connect the positive output terminal of any other dual active bridge except the first-stage dual active bridge to the positive output terminal of the first-stage dual active bridge; one second parallel relay is used to connect the negative output terminal of any other dual active bridge except the first-stage dual active bridge to the negative output terminal of the first-stage dual active bridge; the positive output terminal of the first-stage dual active bridge is connected to the positive power supply terminal of the load, and the negative output terminal of the last-stage dual active bridge is connected to the negative power supply terminal of the load.

[0006] The present invention realizes series-parallel switching of multiple dual active bridges through relay switching. In addition, relay self-checking is introduced to determine whether a relay fails. This method not only realizes wide-range output of the converter, improves the power level, realizes smooth switching of series-parallel without inrush current, but also can identify the failed relay.

[0007] In an optional embodiment, the control device for series-parallel switching of dual active bridges further includes: an output relay, wherein the positive output terminal of the first-stage dual active bridge is connected to the positive power supply terminal of the load through the output relay.

[0008] In a second aspect, the present invention provides a control method for series - parallel switching of a dual - active bridge, based on the optional embodiment of the first aspect of the dual - active bridge series - parallel switching control device. The method includes: determining the working mode of the current dual - active bridge; controlling the corresponding target relay to be energized based on the working mode of the current dual - active bridge; and after controlling the target relay to be energized, determining whether the target relay and the remaining relays are faulty.

[0009] In an optional embodiment, the process of controlling the corresponding target relay to be energized includes: if the current dual - active bridge is in the series working mode, taking the series relay as the target relay, controlling the series relay to be energized, and controlling the first parallel relay and the second parallel relay to be de - energized; if the current dual - active bridge is in the parallel working mode, taking the first parallel relay and the second parallel relay as the target relays, controlling the first parallel relay and the second parallel relay to be energized, and controlling the series relay to be de - energized.

[0010] In an optional embodiment, if the current dual - active bridge is in the series working mode, the process of determining whether the target relay and the remaining relays are faulty includes: after controlling the series relay to be energized, determining whether the series relay, the first parallel relay, and the second parallel relay are energized; if the series relay is not normally energized, determining that the series relay is faulty; if the first parallel relay is energized, determining that the first parallel relay is faulty; if the second parallel relay is energized, determining that the second parallel relay is energized.

[0011] In an optional embodiment, if the current dual - active bridge is in the parallel working mode, the process of determining whether the target relay and the remaining relays are faulty includes: after controlling the first parallel relay and the second parallel relay to be energized, determining whether the series relay, the first parallel relay, and the second parallel relay are energized; if the first parallel relay is not normally energized, determining that the first parallel relay is faulty; if the second parallel relay is not normally energized, determining that the second parallel relay is faulty; if the series relay is energized, determining that the series relay is faulty.

[0012] In an optional embodiment, before controlling the corresponding target relay to be energized based on the working mode of the current dual - active bridge, it further includes: determining whether the output relay is energized; if the output relay is energized, determining that the output relay is faulty.

[0013] In an alternative embodiment, after controlling the target relay to be energized, if the target relay is not faulty, the method further includes: determining whether the output voltage after the dual active bridges are connected in series or parallel reaches the energizing voltage of the output relay; if the output voltage reaches the energizing voltage of the output relay, controlling the output relay to be energized, otherwise waiting until the output voltage reaches the energizing voltage of the output relay and then controlling the output relay to be energized.

[0014] In a third aspect, the present invention provides a computer device, including: a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the dual active bridge series-parallel switching control method according to the second aspect or any corresponding embodiment thereof.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium, on which computer instructions are stored. The computer instructions are used to cause a computer to perform the dual active bridge series-parallel switching control method according to the second aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 is a composition diagram of a dual active bridge series-parallel switching control device according to an embodiment of the present invention;

[0018] Figure 2 is a composition diagram of another dual active bridge series-parallel switching control device according to an embodiment of the present invention;

[0019] Figure 3 is a flowchart of a dual active bridge series-parallel switching control method according to an embodiment of the present invention;

[0020] Figure 4 is a flowchart of another dual active bridge series-parallel switching control method according to an embodiment of the present invention;

[0021] Figure 5 is a schematic hardware structure diagram of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can also be the internal communication of two components. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] In this embodiment, a dual-active-bridge series-parallel switching control device is provided, as Figure 1 shown, including: at least one series relay RLY1, at least one first parallel relay RLY2, and at least one second parallel relay RLY3, where Figure 1 Taking two dual-active bridges as an example.

[0027] Specifically, one series relay RLY1 is used to connect the negative output terminal of the front-stage dual-active bridge to the positive output terminal of the rear-stage dual-active bridge; one first parallel relay RLY2 is used to connect the positive output terminal of any other dual-active bridge except the first-stage dual-active bridge to the positive output terminal of the first-stage dual-active bridge; one second parallel relay RLY3 is used to connect the negative output terminal of any other dual-active bridge except the first-stage dual-active bridge to the negative output terminal of the first-stage dual-active bridge; the positive output terminal of the first-stage dual-active bridge is connected to the positive power supply terminal of the load, and the negative output terminal of the last-stage dual-active bridge is connected to the negative power supply terminal of the load.

[0028] Specifically, Figure 1 in, DAB1 is the front-stage dual-active bridge and the first-stage dual-active bridge, and DAB2 is the rear-stage dual-active bridge and the last-stage dual-active bridge.

[0029] Specifically, when the output voltage of a DAB is insufficient to supply power to the load, at least two DABs can be connected in series to supply power to the load; when multiple DABs are required to achieve redundant power supply, at least two DABs can be connected in parallel to supply power to the load.

[0030] Specifically, Figure 1 In, when the series relay RLY1 is closed and the first parallel relay RLY2 and the second parallel relay RLY3 are open at the same time, two dual-active bridges are connected in series, that is, DAB1 and DAB2 are connected in series; when the series relay RLY1 is open and the first parallel relay RLY2 and the second parallel relay RLY3 are closed at the same time, two dual-active bridges are connected in parallel, that is, DAB1 and DAB2 are connected in parallel.

[0031] Specifically, Figure 1 In, based on the above analysis, the target relay can be selected according to the current working mode of the dual-active bridge, and the target relay is controlled to be closed while other relays are open. For example: if the working mode is the series mode, the series relay RLY1 is selected as the target relay; if the working mode is the parallel mode, the first parallel relay RLY2 and the second parallel relay RLY3 are selected as the target relay.

[0032] The present invention can make two DABs work in series or parallel mode by switching the relay, realizing a wide voltage range and high-power output. In addition, a relay self-check control method is introduced, which can detect the working state of the relay during the series-parallel switching process and identify the faulty relay. In addition, this method can also achieve smooth switching of series-parallel without inrush current. Compared with the traditional series-parallel switching control method, the present invention not only realizes high-power and wide-range voltage output of two DABs and smooth switching of series-parallel without inrush current, but also can detect the working state of the relay during the relay switching process, increasing the reliability of the circuit.

[0033] In some alternative embodiments, as Figure 2 shown, the dual-active bridge series-parallel switching control device further includes: an output relay BUS_RLY, wherein the positive output terminal of the first-stage dual-active bridge is connected to the positive power supply terminal of the load through the output relay.

[0034] Specifically, in order to further improve safety, an output relay is added between the load and the dual-active bridge. When the dual-active bridge fails, the output relay can be disconnected to cut off the connection between the dual-active bridge and the load.

[0035] Specifically, after the target relay is closed and the output voltage of the dual-active bridge reaches the closing voltage of the output relay, the output relay is controlled to be closed.

[0036] In some alternative embodiments, Figure 1 in order to further improve safety, after the target relay is energized, it is possible to determine whether the target relay is properly energized and whether the non-target relays are abnormally energized, so as to determine whether each relay is operating properly.

[0037] In some alternative embodiments, Figure 2 before the series-parallel switching, it is possible to first determine whether the output relay is in the off state. If the output relay is in the off state, it is determined that the output relay is normal. If the output relay is in the energized state, it is determined that the output relay has a fault.

[0038] In some alternative embodiments, Figure 1 and Figure 2 the relays in are all relays with feedback contacts. The relay can feed back information such as its own current value, voltage value, or resistance value to the control terminal. The control terminal determines whether the relay is in the energized or off state based on the feedback information to determine whether the relay has a fault.

[0039] In this embodiment, a method for controlling the series-parallel switching of a dual-active bridge is provided, and a dual-active bridge series-parallel switching control device based on the alternative embodiments of the above embodiments, that is, based on Figure 1 the structure shown in, as Figure 3 shown, the method includes:

[0040] Step S1: Determine the operating mode of the current dual-active bridge.

[0041] Optionally, the operating modes include a series mode, a parallel mode, etc., which are not limited herein.

[0042] Step S2: Control the corresponding target relay to be energized based on the operating mode of the current dual-active bridge.

[0043] Specifically, referring to Figure 1 , if the operating mode is the series mode, the series relay RLY1 is selected as the target relay; if the operating mode is the parallel mode, the first parallel relay RLY2 and the second parallel relay RLY3 are selected as the target relays.

[0044] Optionally, Figure 1 and Figure 2 take two dual-active bridges as an example, but when the number of dual-active bridges reaches three or more, based on the supply voltage level of the load, some of the dual-active bridges can be selected to be connected in series or in parallel, and the remaining dual-active bridges can be non-operating, or the remaining dual-active bridges can supply power to another load.

[0045] Step S3: After controlling the target relay to be energized, determine whether the target relay and the remaining relays have faults.

[0046] Specifically, referring to Figure 1 , in order to prevent abnormal power supply caused by relay failure after the series - parallel switching of the dual - active bridge, relay self - inspection is introduced. By judging whether the target relay is normally pulled in and whether the non - target relay is abnormally pulled in, the fault of the relay can be determined.

[0047] Optionally, there are several methods for judging whether a relay is pulled in. The following are just examples and not limitations:

[0048] (1) Observation method

[0049] Observing the contact state of the relay is the most direct method. When the relay is pulled in, its contacts will close, forming a circuit path. It can be judged whether the relay is pulled in by visually checking whether the contacts are in close contact. If the relay is equipped with an indicator light, the indicator light will light up when pulled in.

[0050] (2) Auditory method

[0051] When the relay is pulled in, it usually makes a slight "click" sound. This is a sound of mechanical action, and it can be judged whether the relay is pulled in by listening to this sound. This method is applicable in a noisy environment or when the relay is installed in a position that is difficult to directly observe.

[0052] (3) Measurement method

[0053] A multimeter can be used to accurately measure the state of the relay.

[0054] (4) Measuring the coil resistance

[0055] Use the resistance range of the multimeter (usually select R×10Ω or R×1Ω) to measure the resistance of the relay coil. If the resistance value is infinite, it may indicate an open - circuit coil; if the resistance value is close to zero, it may indicate a short - circuit coil. The normal resistance value should conform to the technical parameters of the relay.

[0056] (5) Measuring the contact resistance

[0057] Also use the resistance range of the multimeter to measure the resistance of the relay contacts. For normally - closed contacts, the resistance should be zero, indicating that the contacts are closed; for normally - open contacts, the resistance should be infinite, indicating that the contacts are open. If the contact resistance is not the expected value, it may indicate contact ablation or poor contact.

[0058] (6) Measuring the pull - in voltage and pull - in current

[0059] Use a regulated power supply and an ammeter to gradually increase the voltage applied to the relay coil while monitoring the current. When the sound of the relay closing is heard, record the voltage and current values at this time. These values should match the specifications of the relay. Repeat the measurement several times to obtain more accurate results.

[0060] In some alternative embodiments, the process of controlling the corresponding target relay to close includes:

[0061] (1) If the current dual-active bridge is in series operation mode, take the series relay RLY1 as the target relay, control the series relay RLY1 to close, and control the first parallel relay RLY2 and the second parallel relay RLY3 to open.

[0062] (2) If the current dual-active bridge is in parallel operation mode, take the first parallel relay RLY2 and the second parallel relay RLY3 as the target relays, control the first parallel relay RLY2 and the second parallel relay RLY3 to close, and control the series relay RLY1 to open.

[0063] Specifically, referring to Figure 1 , if the current dual-active bridge is in series operation mode, control the series relay RLY1 to close, control the first parallel relay RLY2 and the second parallel relay RLY3 to open, so that the positive output terminal of DAB1 is connected to the positive power supply terminal of the load, the negative output terminal of DAB1 is connected to the positive output terminal of DAB2, and the negative output terminal of DAB2 is connected to the negative power supply terminal of the load.

[0064] Specifically, referring to Figure 1 , if the current dual-active bridge is in parallel operation mode, control the series relay RLY1 to open, control the first parallel relay RLY2 and the second parallel relay RLY3 to close, so that the positive output terminal of DAB1 is connected to the positive power supply terminal of the load and the positive output terminal of BAB2, and the negative output terminal of DAB1 is connected to the positive output terminal of DAB2 and the negative power supply terminal of the load.

[0065] In some alternative embodiments, if the current dual-active bridge is in series operation mode, the process of determining whether the target relay and the remaining relays are faulty includes:

[0066] (1) After controlling the series relay RLY1 to close, determine whether the series relay RLY1, the first parallel relay RLY2, and the second parallel relay RLY3 are closed;

[0067] (2) If the series relay RLY1 fails to close properly, it is determined that the series relay RLY1 is faulty; if the first parallel relay RLY2 closes, it is determined that the first parallel relay RLY2 is faulty; if the second parallel relay RLY3 closes, it is determined that the second parallel relay RLY3 closes.

[0068] In some alternative embodiments, when the current dual active bridge is in the parallel operating mode, the process of determining whether the target relay and the remaining relays are faulty includes:

[0069] (1) After controlling the first parallel relay RLY2 and the second parallel relay RLY3 to close, determine whether the series relay RLY1, the first parallel relay RLY2, and the second parallel relay RLY3 are closed;

[0070] (2) If the first parallel relay RLY2 fails to close properly, it is determined that the first parallel relay RLY2 is faulty; if the second parallel relay RLY3 fails to close properly, it is determined that the first parallel relay RLY2 is faulty; if the series relay RLY1 closes, it is determined that the series relay RLY1 is faulty.

[0071] In some alternative embodiments, before controlling the corresponding target relay to close based on the operating mode of the current dual active bridge, it further includes:

[0072] (1) Determine whether the output relay is closed;

[0073] (2) If the output relay is closed, it is determined that the output relay is faulty.

[0074] Specifically, referring to Figure 2 , before the series-parallel switching, it is possible to first determine whether the output relay is in the open state. If the output relay is in the open state, it is determined that the output relay is normal; if the output relay is in the closed state, it is determined that the output relay is faulty.

[0075] In some alternative embodiments, after controlling the target relay to close, if the target relay is not faulty, the method further includes:

[0076] (1) Determine whether the output voltage after the series or parallel connection of the dual active bridge reaches the closing voltage of the output relay;

[0077] (2) If the output voltage reaches the closing voltage of the output relay, control the output relay to close; otherwise, wait until the output voltage reaches the closing voltage of the output relay and then control the output relay to close.

[0078] Specifically, since the voltage is established slowly, it takes a certain amount of time for the output relay to close. The output relay will only close when the output voltage reaches the closing voltage, where the closing voltage refers to the minimum voltage at which the relay can close.

[0079] Specifically, referring to Figure 2 、 Figure 4 , when the dual-active bridge is in the series working mode, control the series relay RLY1 to close, and control the first parallel relay RLY2 and the second parallel relay RLY3 to open; then, determine whether the series relay RLY1 is closed. If the series relay RLY1 is not closed, it is determined that the series relay RLY1 is faulty. If the series relay RLY1 is closed, determine whether the first parallel relay RLY2 and the second parallel relay RLY3 are closed; if the first parallel relay RLY2 and the second parallel relay RLY3 are closed, it is determined that the first parallel relay RLY2 and the second parallel relay RLY3 are faulty. If the first parallel relay RLY2 and the second parallel relay RLY3 are not closed, determine whether the output voltage reaches the closing voltage of the output relay. If the output voltage reaches the closing voltage of the output relay, the output relay closes. Otherwise, wait for the output voltage to reach the closing voltage of the output relay, and then the output relay closes.

[0080] Specifically, referring to Figure 2 、 Figure 4 , when the dual-active bridge is in the parallel working mode, control the series relay RLY1 to open, and control the first parallel relay RLY2 and the second parallel relay RLY3 to close; then, determine whether the first parallel relay RLY2 and the second parallel relay RLY3 are closed. If the first parallel relay RLY2 and the second parallel relay RLY3 are not closed, it is determined that the first parallel relay RLY2 and the second parallel relay RLY3 are faulty. If the first parallel relay RLY2 and the second parallel relay RLY3 are closed, determine whether the series relay RLY1 is closed; if the series relay RLY1 is closed, it is determined that the series relay RLY1 is faulty. If the series relay RLY1 is not closed, determine whether the output voltage reaches the closing voltage of the output relay. If the output voltage reaches the closing voltage of the output relay, the output relay closes. Otherwise, wait for the output voltage to reach the closing voltage of the output relay, and then the output relay closes.

[0081] Please refer to Figure 5 , Figure 5 is a schematic structural diagram of a computer device provided by an alternative embodiment of the present invention. As Figure 5As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Each component communicates with each other using different buses and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed within the computer device, including instructions stored in the memory or on the memory to display graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some alternative embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (such as an array of servers, a set of blade servers, or a multi-processor system). Figure 5 In the figure, a processor 10 is taken as an example.

[0082] The processor 10 can be a central processing unit, a network processor, or a combination thereof. Among them, the processor 10 can further include a hardware chip. The above hardware chip can be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The above programmable logic device can be a complex programmable logic device, a field programmable gate array, a generic array logic, or any combination thereof.

[0083] Among them, the memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiments.

[0084] The memory 20 can include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the computer device presented by a kind of landing page of a small program, etc. In addition, the memory 20 can include high-speed random access memory and can also include non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some alternative embodiments, the memory 20 can optionally include a memory remotely set relative to the processor 10, and these remote memories can be connected to the computer device through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0085] The memory 20 can include volatile memory, such as random access memory; the memory can also include non-volatile memory, such as flash memory, a hard disk, or a solid-state drive; the memory 20 can also include a combination of the above types of memory.

[0086] The computer device further includes a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0087] Embodiments of the present invention also provide a computer-readable storage medium. The method according to the embodiments of the present invention can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-transitory machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored as such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code, and when the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiments is implemented.

[0088] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A dual active bridge series-parallel switching control device, characterized in that: include: at least one series relay, at least one first parallel relay and at least one second parallel relay, wherein: One of the series relays is used to connect the negative output terminal of the preceding dual active bridge with the positive output terminal of the succeeding dual active bridge; One of the first parallel relays is used to connect the positive output terminal of any other dual active bridge except the first-stage dual active bridge to the positive output terminal of the first-stage dual active bridge; One of the second parallel relays is used to connect the negative output terminal of any other dual active bridge except the first-stage dual active bridge to the negative output terminal of the first-stage dual active bridge; The positive output terminal of the first-stage dual active bridge is connected to the positive power supply terminal of the load, and the negative output terminal of the last-stage dual active bridge is connected to the negative power supply terminal of the load.

2. The dual active bridge series-parallel switching control device according to claim 1, characterized in that: Also includes: Output relays, where The positive output terminal of the first-stage dual active bridge is connected to the positive power supply terminal of the load through the output relay.

3. A dual active bridge series-parallel switching control method, characterized in that: Based on the dual active bridge series-parallel switching control device according to claim 2, the method comprises: Determine the current working mode of the dual active bridge; Controlling the corresponding target relay to be attracted based on the current working mode of the dual active bridge; After the target relay is controlled to be energized, it is determined whether the target relay and the remaining relays are faulty.

4. The dual active bridge series-parallel switching control method according to claim 3, characterized in that: The process of controlling the corresponding target relay to be energized includes: If the current dual active bridge is in the series working mode, the series relay is used as the target relay, and the series relay is controlled to be closed, and the first parallel relay and the second parallel relay are controlled to be disconnected; If the current dual active bridge is in the parallel working mode, the first parallel relay and the second parallel relay are used as the target relays, and the first parallel relay and the second parallel relay are controlled to be attracted, and the series relay is controlled to be disconnected.

5. The dual active bridge series-parallel switching control method according to claim 4, characterized in that: If the current dual active bridge is in the series working mode, the process of determining whether the target relay and the remaining relays are faulty includes: After the series relay is controlled to be energized, it is determined whether the series relay, the first parallel relay, and the second parallel relay are energized; If the series relay does not normally close, it is determined that the series relay is faulty; if the first parallel relay is closed, it is determined that the first parallel relay is faulty; if the second parallel relay is closed, it is determined that the second parallel relay is closed.

6. The dual active bridge series-parallel switching control method according to claim 4, characterized in that: If the current dual active bridge is in parallel working mode, the process of judging whether the target relay and the remaining relays are faulty includes: After controlling the first parallel relay and the second parallel relay to be energized, determining whether the series relay, the first parallel relay, and the second parallel relay are energized; If the first parallel relay is not normally energized, it is determined that the first parallel relay is faulty; if the second parallel relay is not normally energized, it is determined that the first parallel relay is faulty; if the series relay is energized, it is determined that the series relay is faulty.

7. The dual active bridge series-parallel switching control method according to claim 3, characterized in that: Before controlling the corresponding target relay to be attracted based on the current working mode of the dual active bridge, the method further includes: Determine whether the output relay is energized; If the output relay is energized, it is determined that the output relay is faulty.

8. The dual active bridge series-parallel switching control method according to claim 3, characterized in that: After controlling the target relay to be energized, if the target relay is not faulty, the method further includes: Determine whether the output voltage of the dual active bridges connected in series or in parallel reaches the pull-in voltage of the output relay; If the output voltage reaches the pull-in voltage of the output relay, the output relay is controlled to be pulled in; otherwise, the output relay is controlled to be pulled in after the output voltage reaches the pull-in voltage of the output relay.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the dual active bridge series-parallel switching control method according to any one of claims 3 to 8 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the dual active bridge series-parallel switching control method according to any one of claims 3 to 8.

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