Control method of power conversion circuit, power conversion device, energy storage device and computer readable storage medium
By controlling the switching unit to disconnect and reducing the inward movement of the original side, the problem of increased hardware cost and size caused by the discharge circuit design in the prior art is solved, and rapid energy discharge and stability assurance are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ECOFLOW INC
- Filing Date
- 2025-08-25
- Publication Date
- 2026-07-21
AI Technical Summary
In existing technologies, the discharge circuit design requires a long time to completely discharge energy, which increases hardware costs, wiring difficulty and equipment size, and cannot meet design requirements.
By controlling the switching unit to disconnect and reducing the inward movement of the primary side of the power conversion unit, energy can be rapidly discharged without the need for additional discharge circuit design.
It enables rapid energy dissipation, reduces hardware costs, wiring complexity, and equipment size, while ensuring the safety and stability of the power conversion circuit.
Smart Images
Figure CN122437356A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power electronics technology, and in particular to a control method for a power conversion circuit, a power conversion device, an energy storage device, and a computer-readable storage medium. Background Technology
[0002] In related technologies, to ensure circuit safety, a bleeder resistor is typically connected in parallel across energy storage components such as capacitors, inductors, and switching transistors, providing a path for energy dissipation. Simultaneously, to prevent the bleeder resistor from continuously consuming energy, it is often connected in series with a relay to form a bleeder circuit. This circuit is then connected in parallel across the energy storage component, and the relay in the bleeder circuit is closed when energy dissipation is needed, thus avoiding parasitic power consumption introduced by the bleeder circuit. However, this approach has several drawbacks: firstly, it takes a considerable amount of time for the bleeder circuit to completely dissipate energy; secondly, the bleeder circuit increases the hardware cost, wiring complexity, and overall size of the electronic device. Clearly, current bleeder circuit designs do not adequately meet the design requirements. Summary of the Invention
[0003] In view of this, this application provides a control method for a power conversion circuit, a power conversion device, an energy storage device, and a computer-readable storage medium, which can realize energy discharge without setting up a discharge circuit, and can effectively reduce hardware costs, wiring difficulty, and device size.
[0004] This application provides a control method for a power conversion circuit. The power conversion circuit includes two power conversion units and a switching unit. Each power conversion unit includes a primary-side circuit and a secondary-side circuit. The switching unit includes a switching switch, which controls the output terminals of the two power conversion units to be in a series output state or a parallel output state. The method includes: receiving a state switching command, the state switching command carrying a target output state, wherein the target output state includes a series output state or a parallel output state; when the target output state is inconsistent with the current output state of the two power conversion units, controlling the switching switch of the switching unit to open and each power conversion unit to stop working; acquiring the actual output voltage of the output terminals of the two power conversion units respectively; when an actual output voltage is greater than a preset voltage threshold, starting the corresponding power conversion unit and reducing the primary-side inward shift ratio of the primary-side circuit in the corresponding power conversion unit to reduce the corresponding actual output voltage; when both actual output voltages are less than or equal to the preset voltage threshold, controlling both power conversion units to stop working; controlling the switching unit to switch the output state of the two power conversion units according to the state switching command, and controlling the two power conversion units to work after the switching is completed.
[0005] In one embodiment, reducing the primary-side inward shift ratio of the primary-side circuit in the corresponding power conversion unit to reduce the corresponding actual output voltage includes: reducing the primary-side inward shift ratio of the primary-side circuit in the corresponding power conversion unit according to a preset adjustment step size.
[0006] In one embodiment, reducing the primary-side inward shift ratio of the primary-side circuit in the corresponding power conversion unit to reduce the corresponding actual output voltage includes: adjusting the primary-side inward shift ratio of the corresponding power conversion unit to a preset primary-side inward shift ratio.
[0007] In one embodiment, the state switching command also carries target electrical parameters. Controlling the switching unit to switch the output states of the two power conversion units according to the state switching command, and controlling the two power conversion units to work after the switching is completed, includes: controlling the switching switch of the switching unit to work according to the target output state so that the output terminals of the two power conversion units are in the target output state; and controlling the two power conversion units to work according to the target electrical parameters after the output terminals of the two power conversion units are in the target output state.
[0008] In one embodiment, the switching unit includes a first switch, a second switch, and a third switch. The two power conversion units include a first power conversion unit and a second power conversion unit. The output terminal of the first power conversion unit includes a first positive output terminal and a first negative output terminal. The output terminal of the second power conversion unit includes a second positive output terminal and a second negative output terminal. The first positive output terminal is connected to the second positive output terminal through the first switch, the first negative output terminal is connected to the second negative output terminal through the second switch, and the first negative output terminal is connected to the second positive output terminal through the third switch. The switching unit's operation is controlled according to the target output state, including: when the target output state is a parallel output state, controlling the first and second switches to be turned on and controlling the third switch to be turned off; when the target output state is a series output state, controlling the third switch to be turned on and controlling the first and second switches to be turned off.
[0009] In one embodiment, the state switching command also carries target electrical parameters. After receiving the state switching command, the control method further includes: when the target output state is consistent with the current output state, controlling the two power conversion units to work according to the target electrical parameters.
[0010] In one embodiment, the target electrical parameters include the target total output voltage. Controlling the operation of two power conversion units according to the target electrical parameters includes: determining the target output voltage of the output terminal of each power conversion unit according to the target output state and the target total output voltage; and controlling the operation of the corresponding power conversion unit according to the target output voltage.
[0011] A second aspect of this application provides a power conversion device, including a power conversion circuit and a controller. The power conversion circuit includes two power conversion units and a switching unit. Each power conversion unit includes a primary-side circuit and a secondary-side circuit. The switching unit includes a switching switch and is used to control the output terminals of the two power conversion units to be in a series output state or a parallel output state. The controller is used to execute the control method of the power conversion circuit as described in any of the preceding claims.
[0012] A third aspect of this application provides an energy storage device, including an energy storage battery and a power conversion device as described above. The energy storage battery is connected to the power conversion device to provide direct current to the power conversion device or to store the direct current output by the power conversion device.
[0013] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, can implement the control method for the power conversion circuit as described in any of the preceding claims.
[0014] In summary, the control method for the power conversion circuit provided in this application, upon receiving a state switching command, when confirming that the current output state of the two power conversion units is inconsistent with the target output state carried by the state switching command, controls the switching switches of the switching units to be turned off and each power conversion unit to stop working. Then, it obtains the actual output voltage at the output terminals of the two power conversion units. When the actual output voltage is greater than a preset voltage threshold, it reduces the ratio of the primary side shift in the power conversion unit corresponding to the actual output voltage greater than the preset voltage threshold to reduce the corresponding actual output voltage. In this way, without the need for additional discharge circuit design, the electronic devices inside the two power conversion units can consume energy by reducing the ratio of the primary side shift in, thereby achieving rapid energy discharge at the output terminal, effectively reducing the discharge time, and helping to reduce the hardware cost, wiring difficulty and equipment size of the power conversion circuit. Furthermore, when the energy at the output end is discharged to the point that the actual output voltage is less than the preset voltage threshold, the two power conversion units are controlled to stop working. The switching unit is controlled to switch the output state of the two power conversion units according to the state switching command, and the two power conversion units are controlled to work after the switching is completed. This achieves rapid switching of the output state of the power conversion circuit while ensuring the safety and stability of the power conversion circuit. Attached Figure Description
[0015] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation on the scope of protection of this application. In the various drawings, similar components are numbered similarly.
[0016] Figure 1This is a circuit block diagram of a power conversion circuit provided in an embodiment of this application.
[0017] Figure 2 for Figure 1 The circuit diagram shown is a partial circuit diagram of the power conversion unit.
[0018] Figure 3 for Figure 1 The circuit block diagram shown illustrates the power conversion circuit with a discharge loop.
[0019] Figure 4 This is a flowchart illustrating a control method for a power conversion circuit provided in an embodiment of this application.
[0020] Figure 5 for Figure 2 The timing logic diagram of the DAB circuit is shown.
[0021] Figure 6 for Figure 2 The diagram shows the seven states of the DAB circuit.
[0022] Figure 7 This is a flowchart illustrating a sub-step of step S406 in one embodiment of this application.
[0023] Figure 8 This is a flowchart illustrating the sub-step of controlling the operation of two power conversion units according to target electrical parameters in step S702 of one embodiment of this application.
[0024] Figure 9 A flowchart illustrating a control method for a power conversion circuit provided in another embodiment of this application.
[0025] Figure 10 This is a schematic diagram of the actual output voltage curve when the voltage at the output terminal of the power conversion unit corresponding to the power conversion circuit in one embodiment of this application is naturally consumed.
[0026] Figure 11 This is a schematic diagram of the actual output voltage curve of the corresponding power conversion unit when the power conversion circuit in one embodiment of the present application performs a control method for the power conversion circuit and discharges energy by reducing the primary side inward shift ratio.
[0027] Figure 12 This is a functional block diagram of a power conversion device provided in an embodiment of this application.
[0028] Figure 13 A functional block diagram of an energy storage device provided in an embodiment of this application.
[0029] Figure 14 This is a functional block diagram of a control device provided in an embodiment of this application.
[0030] Figure 15 A functional block diagram of a computer-readable storage medium provided in an embodiment of this application. Detailed Implementation
[0031] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.
[0032] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have an intervening component. When a component is considered to be "placed" on another component, it can be directly placed on the other component or may also have an intervening component.
[0033] It should also be noted that the methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged, and some steps can also be deleted.
[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.
[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0036] Some embodiments will now be described with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0037] First, please refer to Figure 1 , Figure 1This is a circuit block diagram of a power conversion circuit 10 provided in one embodiment of this application. The power conversion circuit 10 includes at least two power conversion units, such as a first power conversion unit 110 and a second power conversion unit 120, and a switching unit 130. Each power conversion unit is used to implement forward power transmission or reverse power transmission. For example, when the power conversion unit implements forward transmission, it converts the power at the input terminal and outputs a preset power at the output terminal. When the power conversion unit implements reverse transmission, it converts the power at the output terminal and outputs a preset power at the input terminal. The power conversion unit can be a DC-DC conversion unit or a DC-AC conversion unit. This application does not limit the specific circuit type of the power conversion unit. That is, the input terminal of the power conversion unit can be a DC input terminal or an AC input terminal, and the output terminal of the power conversion unit can be a DC output terminal or an AC output terminal. This application does not limit the specific circuit type of the power conversion unit. In this application, a DC-DC conversion unit is used as an example of the power conversion unit. The switching unit 130 is used to control the output terminals of the two power conversion units to be in series output state or parallel output state.
[0038] The first power conversion unit 110 has an input terminal including a first positive input terminal IN1+ and a first negative input terminal IN1-. The first power conversion unit 110 also has an output terminal including a first positive output terminal OUT1+ and a first negative output terminal OUT1-. The second power conversion unit 120 has an input terminal including a second positive input terminal IN2+ and a second negative input terminal IN2-. The second power conversion unit 120 also has an output terminal including a second positive output terminal OUT2+ and a second negative output terminal OUT2-. The switching unit 130 includes a switching switch; for example, the switching switch includes a first switch, a second switch, and a third switch.
[0039] In this configuration, the first positive input terminal IN1+ and the second positive input terminal IN2+ are both connected to the positive transmission terminal VIN+, and the first negative input terminal IN1- and the second negative input terminal IN2- are both connected to the negative transmission terminal VIN-. The first positive output terminal OUT1+ is connected to the positive transmission bus BUS+, which is also connected to the positive connection terminal BAT+. The first positive output terminal OUT1+ is also connected to the second positive output terminal OUT2+ via the first switch K1. The first negative output terminal OUT1- is connected to the negative transmission bus BUS- via the second switch K2, and the second negative output terminal OUT2- is connected to the negative transmission bus BUS-, which is also connected to the negative connection terminal BAT-. Thus, the first negative output terminal OUT1- is connected to the second negative output terminal OUT2- via the second switch K2. The first negative output terminal OUT1- is also connected to the second positive output terminal OUT2+ via the third switch K3. In some embodiments, the first switch K1 and the second switch K2 are two relays connected in parallel, and both are normally open relays. The third switch K3 may include two relays connected in series. The third switch being on means both relays are conducting, and the third switch being off means at least one of the relays is off. Thus, when the first switch K1 and the second switch K2 are on, and the third switch K3 is off, the outputs of the first power conversion unit 110 and the second power conversion unit 120 are in a parallel output state. When the first switch K1 and the second switch K2 are off, and the third switch K3 is on, the outputs of the first power conversion unit 110 and the second power conversion unit 120 are in a series output state.
[0040] For example, the positive transmission terminal VIN+ and the negative transmission terminal VIN- can serve as the high-voltage side and be connected to, for example, a charger or load, while the positive connection terminal BAT+ and the negative connection terminal BAT- can serve as the low-voltage side and be connected to an energy storage battery or any device equipped with an energy storage battery, such as a battery pack. Thus, the power conversion circuit 10 can realize the conversion of energy between the high-voltage side and the low-voltage side. In particular, when both power conversion units are bidirectional power conversion units, bidirectional conversion of energy between the high-voltage side and the low-voltage side can also be realized.
[0041] In some embodiments, a capacitor C1 is connected between the first positive output terminal OUT1+ and the first negative output terminal OUT1-, a capacitor C2 is connected between the second positive output terminal OUT2+ and the second negative output terminal OUT2-, and a capacitor C3 is connected between the positive transmission terminal VIN+ and the negative transmission terminal VIN-. This helps to stabilize the voltage at each terminal of the power conversion circuit 10.
[0042] In some embodiments, the power conversion circuit 10 further includes a main switching circuit 140 and a pre-charging circuit 150. The positive transmission bus BUS+ is connected to a first terminal of the main switching circuit 140, and the second terminal of the main switching circuit 140 is connected to the positive connection terminal BAT+. The first terminal of the pre-charging circuit 150 is connected between the positive transmission bus BUS+ and the first terminal of the main switching circuit 140, and the second terminal of the pre-charging circuit 150 is connected between the second terminal of the main switching circuit 140 and the positive connection terminal BAT+. Thus, when the pre-charging circuit 150 is turned on, it can provide voltage to the positive connection terminal BAT+ and the negative connection terminal BAT-. When the voltage between the positive connection terminal BAT+ and the negative connection terminal BAT- rises to the pre-charging voltage threshold, the pre-charging circuit 150 can be turned off and the main switching circuit 140 can be turned on, thereby switching from the pre-charging state to the normal power supply state, thereby reducing the safety risks of the power conversion circuit 10.
[0043] The main switch circuit 140 may include a relay K4, and the pre-charging circuit 150 may include a relay K5 and a current-limiting resistor R1. In other embodiments, the main switch circuit 140 and the pre-charging circuit 150 may also have other circuit structures. This application does not limit the specific circuit structure of the main switch circuit 140 and the pre-charging circuit 150.
[0044] In some embodiments, each power conversion unit includes a primary-side circuit and a secondary-side circuit. Please continue reading. Figure 2 Taking the first power conversion unit 110 as an example, the first power conversion unit 110 includes a primary circuit 111, a secondary circuit 112, and a resonant cavity 113. The primary circuit 111 and the secondary circuit 112 are coupled through the resonant cavity 113. The primary circuit 111 is a DC / AC conversion circuit, and the secondary circuit 112 is an AC / DC conversion circuit.
[0045] The primary circuit 111 includes switching transistors Q1, Q2, Q3, and Q4. The secondary circuit 112 includes switching transistors Q5, Q6, Q7, and Q8. The resonant cavity 113 includes a first resonant inductor L1 and a first transformer T1. The first terminals of switching transistors Q1 and Q3 are electrically connected to the first positive input terminal IN1+. The second terminal of switching transistor Q1 is electrically connected to the first terminal of switching transistor Q2. The second terminal of switching transistor Q3 is electrically connected to the first terminal of switching transistor Q4. The second terminals of switching transistors Q2 and Q4 are both electrically connected to the first negative input terminal IN1-. The first terminal of the first resonant inductor L1 is connected to the midpoint a between switching transistors Q1 and Q2, and the second terminal of the first resonant inductor L1 is electrically connected to the first terminal of the first winding of transformer T1. The second terminal of the first winding of transformer T1 is electrically connected between the second terminal of switching transistor Q1 and the first terminal of switching transistor Q2, i.e., the midpoint b. The first terminal of the second winding of transformer T1 is electrically connected to the second terminal of switching transistor Q7, i.e., midpoint d. The second terminal of the second winding of transformer T1 is electrically connected to the second terminal of switching transistor Q5, i.e., midpoint c. The first terminals of both switching transistors Q7 and Q5 are electrically connected to the first positive output terminal OUT1+. The second terminal of switching transistor Q5 is also electrically connected to the first terminal of switching transistor Q6. The second terminal of switching transistor Q7 is also electrically connected to the first terminal of switching transistor Q8. The second terminals of both switching transistors Q6 and Q8 are electrically connected to the first negative output terminal OUT1-.
[0046] The primary-side circuit 111 includes two bridge arms. One bridge arm 1111 consists of switches Q1 and Q2, and the other bridge arm 1112 consists of switches Q3 and Q4. When the primary-side circuit 111 is operating, switches Q1 and Q4 form one group, and switches Q3 and Q2 form the other group. Switches in the same group are turned on or off simultaneously, while switches in different groups are turned on alternately. That is, in each cycle, one group of switches is on for half the cycle, and the other group is on for the other half. Furthermore, after one group of switches is turned off, the other group is turned on after a dead time delay. Switches Q5, Q6, Q7, and Q8 in the secondary-side circuit 112 correspond one-to-one with switches Q1, Q2, Q3, and Q4 in the primary-side circuit 111. Furthermore, the working principle of the secondary circuit 112 is roughly the same as that of the primary circuit 111, and will not be described in detail here. The first power conversion unit 110 can realize bidirectional conversion of energy between the input end, i.e., the first positive input terminal IN1+ and the first negative input terminal IN1-, and the output end, i.e., the first positive output terminal OUT1+ and the first negative output terminal OUT1-.
[0047] When energy flows from the input to the output, the primary circuit 111 acts as the input-side bridge arm circuit to convert the DC power at the input to AC power and output it to the resonant cavity 113. The secondary circuit 112 acts as the output-side bridge arm circuit to convert the AC power output from the resonant cavity 113 to DC power and output it through the output terminal. When energy flows from the output to the input, the secondary circuit 112 acts as the input-side bridge arm circuit to convert the DC power at the output to AC power and output it to the resonant cavity 113. The primary circuit 111 acts as the output-side bridge arm circuit to convert the AC power output from the resonant cavity 113 to DC power and output it through the input terminal.
[0048] The circuit structure and working principle of the second power conversion unit 120 are roughly the same as those of the first power conversion unit 110, and will not be described again here.
[0049] Understandably, the switching transistors mentioned in this application are, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors).
[0050] In related technologies, to ensure circuit safety, a bleeder resistor is typically connected in parallel across energy storage components such as capacitors, inductors, and switching transistors, providing a path for energy dissipation. Simultaneously, to prevent the bleeder resistor from continuously consuming energy, it is often connected in series with a relay to form a bleeder circuit. This circuit is then connected in parallel across the energy storage component, and the relay in the bleeder circuit is closed when energy dissipation is needed, thus avoiding parasitic power consumption introduced by the bleeder circuit. Figure 1 The power conversion circuit 10 shown is an example; please refer to [link / reference]. Figure 3 According to relevant technologies, a discharge circuit 160 can be set between the positive connection terminal BAT+ and the negative connection terminal BAT- of the power conversion circuit 10. Thus, regardless of whether the switch is switching from a series output state to a parallel output state or vice versa, to prevent residual voltage on capacitor C1 or capacitor C2 from causing instantaneous overcurrent and sticking of the switching switch in the switching unit 130 at the moment of closure, it is necessary to wait for the voltage on capacitors C1 and C2 to discharge to a low value, ensuring that the voltage difference between capacitors C1 and C2 is less than or equal to a preset voltage threshold, before controlling the switching switch in the switching unit 130 to perform the switching operation.
[0051] However, this approach has several drawbacks. First, it takes a considerable amount of time for the discharge circuit 160 to completely discharge the energy. Second, the discharge circuit 160 increases the hardware cost, wiring complexity, and size of the electronic device housing the power conversion circuit 10. Clearly, the current discharge circuit design does not adequately meet the design requirements.
[0052] Based on this, this application provides a control method for a power conversion circuit, a power conversion device, an energy storage device, and a computer-readable storage medium, which can realize energy discharge without setting up a discharge circuit, effectively reducing hardware costs, wiring difficulty, and device size.
[0053] In the following embodiment, the control method of the power conversion circuit is applied... Figure 1 The power conversion circuit 10 shown is used as an example to illustrate the working principle and process of the control method for the power conversion circuit provided in this application. It is worth noting that the control method for the power conversion circuit provided in this application can also be applied to other circuits that include at least two power conversion units and require a switching unit to change the output state of at least two power conversion units. This application does not specifically limit the circuit structure to which the control method for the power conversion circuit is applied.
[0054] Please see Figure 4 , Figure 4 This is a flowchart illustrating a control method for a power conversion circuit according to an embodiment of this application. It can be understood that this control method can be implemented by a controller of the power conversion circuit 10. Figure 1 (Not shown) is executed. The control method for the power conversion circuit includes the following steps S401-S406.
[0055] Step S401: Receive a state switching instruction. The state switching instruction carries the target output state, wherein the target output state includes a series output state or a parallel output state.
[0056] In some embodiments, the controller of the power conversion circuit 10 can communicate with another controller loaded with an Energy Management System (EMS), and the state switching command can be sent by the EMS. In other embodiments, the state switching command can be sent to the controller of the power conversion circuit 10 by a user triggering a corresponding button / control on an electronic device (e.g., a smartphone or control terminal) with an application (APP) installed. Alternatively, the state switching command can be sent to the controller of the power conversion circuit 10 in response to a user's key press or touch operation on the electronic device where the power conversion circuit 10 is located. This application does not limit the source of the state switching command.
[0057] In some embodiments, after receiving a state switching command, the controller of the power conversion circuit 10 can parse the state switching command to obtain a data frame, and then determine the target state based on the data frame.
[0058] In this embodiment, when the two power conversion units are in a series output state, the first positive output terminal OUT1+ of the first power conversion unit 110 is connected to the positive transmission bus BUS+, the first negative output terminal OUT1- of the first power conversion unit 110 is connected to the second positive output terminal OUT2+ of the second power conversion unit 120 via the switching unit 130, and the second negative output terminal OUT2- of the second power conversion unit 120 is connected to the negative transmission bus BUS-. When the two power conversion units are in a parallel output state, the second positive output terminal OUT2+ of the second power conversion unit 120 is connected to the first positive output terminal OUT1+ of the first power conversion unit 110 via the switching unit 130, and the second negative output terminal OUT2- of the second power conversion unit 120 is connected to the first negative output terminal OUT1- of the first power conversion unit 110 via the switching unit 130.
[0059] Step S402: When the target output state is inconsistent with the current output state of the two power conversion units, the switching switches of the control switching unit are all turned off and each power conversion unit stops working.
[0060] It is understandable that when the target output state is inconsistent with the current output state of the two power conversion units, it indicates that the switching switch in the switching unit 130 should be activated to switch the output state of the two power conversion units. In this case, the switching switches in the switching unit 130 are first activated and each power conversion unit stops working in preparation for the switching.
[0061] Step S403: Obtain the actual output voltage of the output terminals of the two power conversion units respectively.
[0062] Understandably, voltage sampling circuits can be provided at the output terminals of the first power conversion unit 110 (i.e., the first positive output terminal OUT1+ and the first negative output terminal OUT1-) and the output terminals of the second power conversion unit 120 (i.e., the second positive output terminal OUT2+ and the second negative output terminal OUT2-), respectively, to sample the actual output voltages of the two power conversion units, i.e., the voltages across capacitor C1 and capacitor C2, according to a preset sampling period. This application does not limit the duration of the preset sampling period.
[0063] Step S404: When the actual output voltage is greater than the preset voltage threshold, start the corresponding power conversion unit and reduce the primary side shift ratio of the primary side circuit in the corresponding power conversion unit to reduce the corresponding actual output voltage.
[0064] The preset voltage threshold in step S404 represents the safe voltage limit of the switching switch in the switching unit 130. That is, when the actual output voltage is greater than the preset voltage threshold, it indicates that the actual output voltage poses a risk of causing the switching switch to overcurrent and sticking at the moment of closing. When the actual output voltage is less than or equal to the preset voltage threshold, it indicates that the risk of the actual output voltage causing the switching switch to overcurrent at the moment of closing is low, and the corresponding switching switch can be closed. Thus, when the actual output voltage of one power conversion unit is greater than the preset voltage threshold, or the actual voltages of both power conversion units are greater than the preset voltage threshold, it is necessary to reduce the actual output voltage of the power conversion unit corresponding to the actual output voltage greater than the preset voltage threshold. The preset voltage threshold can be, for example, 20V. This application does not limit the specific value of the preset voltage threshold; in other embodiments, the preset voltage threshold can also be other values.
[0065] Please refer to the following: Figure 2 , Figure 5 and Figure 6 Both the first power conversion unit 110 and the second power conversion unit 120 include Figure 2 The illustrated example of a dual active bridge (DAB) circuit, as described above, shows that each power conversion unit can be configured according to... Figure 5 The timing logic diagram shown illustrates the operation. Under the DPS (Dual Phase Shift Control) strategy, in normal operation, adjusting the outer phase shift ratio Dφ ensures the output power meets expectations, while adjusting the inner phase shift ratio Dy1 reduces losses. The outer phase shift ratio Dφ represents the phase difference between the drive signals of the corresponding switches in the two full-bridge circuits of the DAB circuit. The inner phase shift ratio Dy1 represents the phase difference between the drive signals of diagonal switches within the same full-bridge circuit.
[0066] Specifically, taking the DAB circuit in the first power conversion unit 110 as an example, its single-cycle operating modes include Figure 6 The seven states are shown. From Figure 6 It can be seen that in states (a), (d), (e), (f), and (g), energy interaction occurs between the actual output voltage and the first resonant inductor L1. The current in these five states flows through the four switches, transformer T1, and the first resonant inductor L1, resulting in some energy loss. Furthermore, under the DPS strategy, the operating principle of the DAB circuit dictates that the switches in the same bridge arm of the first power conversion unit 110 are complementary and have a duty cycle of 50%. Thus, switches Q5 and Q8 in the secondary circuit 112 are simultaneously turned on or off, and the shift inwards corresponds to the time of Dy1 (i.e.,...). Figure 5In the equation Dy1*Ts / 2, where Ts represents the period, the time during which switching transistors Q1 and Q4 are simultaneously on can be reduced by decreasing the inward shift relative to Dy1. This reduces the duration of the DAB circuit in states (b) and (c), and consequently increases the duration of the DAB circuit in states (a), (d), (e), (f), and (g). This increases the energy loss of the circuit after the first power conversion unit 110 is started, thereby achieving the goal of rapidly reducing the actual output voltage at the output terminal of the first power conversion unit 110. In other words, by executing step S404, the reactive power components in the DAB circuit of the power conversion unit, as well as the switching and conduction losses of each switching transistor, and the losses caused by transformer magnetic losses and line impedance, can be utilized to meet the requirement of rapid discharge of the port capacitor of the power conversion unit without adding an additional discharge circuit. It can be understood that the method provided in step S404 is applicable to circuit topologies where reactive power circulating current exists during operation.
[0067] Step S405: When both actual output voltages are less than or equal to the preset voltage threshold, control both power conversion units to stop working.
[0068] When both actual output voltages are less than or equal to the preset voltage threshold, it indicates that the risk of overcurrent caused by the switching switch closing at this time is low. At this point, both power conversion units can be controlled to stop operating, thereby improving the safety of the subsequent switching unit 130 when switching the output states of the two power conversion units.
[0069] Step S406: Control the switching unit to switch the output states of the two power conversion units according to the state switching command, and control the two power conversion units to work after the switching is completed.
[0070] It is understood that by executing steps S401-S405, the actual output voltages of the two power conversion units are both less than or equal to the preset voltage threshold, both power conversion units stop working, and the switching switches in the switching unit 130 are both turned off. At this time, the switching unit controls the switching unit to switch the output state of the two power conversion units according to the state switching command, and controls the two power conversion units to work after the switching is completed. This can ensure the safety and stability of the output state switching of the two power conversion units, so that the power conversion circuit 10 that can achieve safe switching of output state can meet various power demand scenarios.
[0071] In summary, the control method for the power conversion circuit provided in this application, upon receiving a state switching command, when it is confirmed that the current output state of the two power conversion units is inconsistent with the target output state carried by the state switching command, controls the switching switches of the switching unit 130 to be turned off and each power conversion unit to stop working. Then, it obtains the actual output voltage of the output terminals of the two power conversion units. When the actual output voltage is greater than a preset voltage threshold, it reduces the ratio of the primary side shift in the power conversion unit corresponding to the actual output voltage greater than the preset voltage threshold to reduce the corresponding actual output voltage. In this way, without the need for additional discharge circuit design, the electronic devices inside the two power conversion units can consume energy by reducing the ratio of the primary side shift in, thereby achieving rapid energy discharge at the output terminal, effectively reducing the discharge time, and helping to reduce the hardware cost, wiring difficulty and equipment size of the power conversion circuit. Furthermore, when the energy at the output end is discharged to the point that the actual output voltage is less than the preset voltage threshold, the two power conversion units are controlled to stop working, and the switching unit is controlled to switch the output state of the two power conversion units according to the state switching command. After the switching is completed, the two power conversion units are controlled to work, thereby achieving rapid switching of the output state of the power conversion circuit 10 while ensuring the safety and stability of the power conversion circuit 10.
[0072] In some embodiments, after executing step S403, when the actual output voltage of both power conversion units is less than or equal to a preset voltage threshold, step S406 is executed directly to switch the output state of the power conversion circuit 10 to the target state for operation.
[0073] In some embodiments, step S404 includes: reducing the primary side of the primary circuit in the corresponding power conversion unit by a preset adjustment step size.
[0074] The preset adjustment step size is used to represent the amount of change compared to each adjustment of the original side inward. In some embodiments, the preset adjustment step size can be a preset value, and the preset adjustment step size can be set according to the specific circuit parameters of each power conversion unit. This application does not limit the specific value of the preset adjustment step size.
[0075] Thus, after activating the corresponding power conversion unit, by gradually reducing the inward movement of the primary side of the corresponding power conversion unit according to the preset adjustment step size, the energy at the output end of the corresponding power conversion unit can be discharged quickly, while reducing the overcurrent risk of the DAB circuit and achieving a smooth transition during the energy discharge process.
[0076] In other embodiments, the preset adjustment step size can also be a dynamically changing value. Furthermore, the preset adjustment step size can be adjusted based on the voltage difference between the actual output voltage and a preset voltage threshold. For example, the preset adjustment step size can be configured to have a positive correlation with the voltage difference. Thus, when the actual output voltage is greater than the preset voltage threshold, and the difference between the actual output voltage and the preset voltage threshold is larger, reducing the primary side inward of the corresponding power conversion unit by a larger preset adjustment step size can further improve the energy dissipation speed at the output of the corresponding power conversion unit, thereby reducing the actual output voltage at the output terminal more quickly.
[0077] In summary, by adjusting the step size according to the preset value and shifting the primary side of the primary circuit in the corresponding power conversion unit inward, the overcurrent risk of the corresponding power conversion unit can be reduced, and a smooth transition can be achieved during the energy dissipation process.
[0078] In another embodiment, step S404 includes: adjusting the primary side inward shift ratio of the corresponding power conversion unit to a preset primary side inward shift ratio.
[0079] Understandably, the preset primary-side inward shift ratio involved in this application is greater than 0 and less than 1. For example, the preset primary-side inward shift ratio can be 0.1. This application does not limit the specific value of the preset primary-side inward shift ratio. Thus, in this embodiment, by directly adjusting the primary-side inward shift ratio of the corresponding power conversion unit to the preset primary-side inward shift ratio, the energy dissipation speed can be improved and the adjustment time reduced.
[0080] Please see Figure 7 In some embodiments, when the state switching command carries target electrical parameters, step S406 includes the following steps S701-S702.
[0081] Step S701: Control the switching switch of the switching unit to work according to the target output state so that the output terminals of the two power conversion units are in the target output state.
[0082] In some embodiments, the controller of the power conversion circuit 10 can control the switching switches in the switching unit 130 to operate according to a preset lookup table, so that the output terminals of the two power conversion units are in the target output state. The preset lookup table records the on / off state of each switching switch in the switching unit 130 corresponding to the series output state and the parallel output state, respectively.
[0083] Step S702: After the output terminals of the two power conversion units are in the target output state, control the two power conversion units to work according to the target electrical parameters.
[0084] Target electrical parameters are used to represent a given parameter associated with each power conversion unit. For example, a target electrical parameter may be at least one of a target output power, a target output voltage, a target output current, and other target electrical parameters. In some embodiments, different target output states may correspond to different target electrical parameters. For instance, when the target output state is a series output state, the target electrical parameter may include the target total output voltage of the two power conversion units, for example, 800V. When the target output state is a parallel output state, the target electrical parameter may include the given output voltage of each power conversion unit, for example, 400V for each.
[0085] It is understood that in step S702, the two power conversion units can be controlled to operate according to the target electrical parameters and a preset control loop. The preset control loop may include at least one of a voltage loop, current loop, power loop, combined loop, or other control loops. This application does not limit the specific loop. The preset control loop may include one or more control loops / controllers, such as adders, subtractors, derivative controllers (D), proportional-integral (PI) controllers, proportional-integral-derivative (PI-D) controllers, limiters, etc., and this application does not limit these. It is understood that different algorithms can be used to control the two power conversion units to operate according to the target electrical parameters, depending on the design of the preset control loop.
[0086] In summary, by executing steps S701-S702, when the actual output voltages at the output terminals of the two power conversion units drop to or below a preset voltage threshold, the switching unit 130 can be quickly controlled to switch the output states of the two power conversion units according to the state switching command, and the two power conversion units can be controlled to work after the switching is completed to meet the user's power requirements.
[0087] Please refer to the following: Figure 1 In some embodiments, when the switching unit 130 includes a first switch K1, a second switch K2, and a third switch K3, step S701 includes:
[0088] When the target output state is parallel output state, control the first switch K1 and the second switch K2 to be turned on, and control the third switch K3 to be turned off;
[0089] When the target output state is a series output state, control the third switch K3 to turn on, and control the first switch K1 and the second switch K2 to turn off.
[0090] Specifically, when the outputs of the two power conversion units are in series output mode, the power conversion circuit 10 can support a higher output voltage; when the outputs of the two power conversion units are in parallel output mode, the power conversion circuit 10 can support a larger output current. Thus, by controlling the switching switch of the switching unit 130, the power conversion circuit 10 can switch between two output states to adapt to more application scenarios and meet more diverse power needs of users.
[0091] Thus, based on Figure 1 The circuit design of the switching unit 130 allows for flexible switching of the output states of the two power conversion units in the power conversion circuit 10 by controlling the first switch K1, the second switch K2, and the third switch K3. Furthermore, since the energy at the output of the corresponding power conversion unit has been discharged before step S701 by reducing the internal shift ratio, the overcurrent risk during switching of the first switch K1, the second switch K2, and the third switch K3 in the switching unit 130 is greatly reduced.
[0092] In some embodiments, when the state switching command carries target electrical parameters, the control method of the power conversion circuit after receiving the state switching command further includes:
[0093] When the target output state is consistent with the current output state, the two power conversion units are controlled to work according to the target electrical parameters.
[0094] Similarly, at this point, the two power conversion units can be controlled to operate separately based on the target electrical parameters and the preset control loop. Further details will not be elaborated here.
[0095] Please see Figure 8 In some embodiments, the target electrical parameters include the target total output voltage. Step S702, which controls the operation of the two power conversion units according to the target electrical parameters, includes:
[0096] Step S801: Determine the target output voltage of each power conversion unit's output terminal based on the target output state and the target total output voltage.
[0097] The target total output voltage is used to represent the total output voltage at the output terminal of the power conversion circuit 10, that is, the target value of the total output voltage between the positive transmission bus BUS+ and the negative transmission bus BUS-.
[0098] In step S801, when the target output state is a parallel output state, the target output voltage at the output terminal of each power conversion unit is determined to be equal to the total target output voltage. When the target output state is a series output state, a target output voltage is allocated to each power conversion unit according to the total target output voltage. For example, in some embodiments, the target output voltage of each power conversion unit can be configured to be equal to half of the total target output voltage. In other embodiments, when the target output state is a series output state, the target output voltages of the two power conversion units may not be equal; it is sufficient that the sum of the target output voltages of the two power conversion units equals the total target output voltage. This application does not limit the specific algorithm for determining the target output voltage at the output terminal of each power conversion unit according to the target output state and the total target output voltage in step S801. In other embodiments, other algorithms may also be used to determine the target output voltage at the output terminal of each power conversion unit.
[0099] Step S802: Control the operation of the corresponding power conversion unit according to the target output voltage.
[0100] In some embodiments, the actual output voltage of each power conversion unit can be sampled, and then the voltage deviation between the actual output voltage and the corresponding target output voltage can be calculated. The voltage deviation is then adjusted to calculate the control signal corresponding to each power conversion unit. The control signal can be a pulse width modulation (PWM) signal. Thus, the conduction logic and duty cycle of the switching transistors in the corresponding power conversion unit can be controlled based on the PWM signal, thereby achieving the purpose of controlling the operation of the corresponding power conversion unit according to the target output voltage.
[0101] Understandably, the deviation adjustment mentioned in this application can be based on at least one of the following algorithms: PID (Proportion-Integration Differential control), PI (Proportional-Integral control), etc., or other adjustment algorithms. This application does not limit the specific algorithm used for deviation adjustment.
[0102] In summary, by executing steps S801-S802, the operation of the two power conversion units can be effectively controlled according to the target electrical parameters.
[0103] Please see Figure 9An embodiment of this application also provides a control method for a power conversion circuit, including the following steps S901-S912. It is understood that this control method for the power conversion circuit can also be executed by a controller of the power conversion circuit.
[0104] Step S901: Start the power conversion circuit.
[0105] In some embodiments, after the power conversion circuit 10 is started, it can operate according to an initial preset state. The initial preset state can be configured so that the output states of the output terminals of the first power conversion unit 110 and the second power conversion unit 120 are either a series output state or a parallel output state.
[0106] Step S902: Determine whether to establish communication with EMS.
[0107] Step S903: If communication with EMS is not established, determine whether the communication timeout has occurred.
[0108] If communication with EMS is not established within a preset time period, it is determined that the power conversion circuit 10 has experienced a communication timeout.
[0109] Step S904: When a communication timeout is determined, the control power conversion circuit stops working and reports a communication fault.
[0110] Step S905: When communication is established with EMS, a status switching instruction is received, and the status switching instruction carries the target output status.
[0111] Step S906: When the target output state is consistent with the current output state of the two power conversion units, control the two power conversion units to work according to the target electrical parameters carried by the state switching command.
[0112] Step S907: When the target output state is inconsistent with the current output state of the two power conversion units, the switching switches of the control switching unit are all turned off and each power conversion unit stops working.
[0113] Step S908: Obtain the actual output voltage of the output terminals of the two power conversion units respectively.
[0114] Step S909: When the actual output voltage of both power conversion units is less than or equal to the preset voltage threshold, control the switching unit to switch the output state of the two power conversion units according to the state switching command, and control the two power conversion units to work after the switching is completed.
[0115] Step S910: When any actual output voltage is greater than a preset voltage threshold, start the power conversion unit corresponding to the actual output voltage that is greater than the preset voltage threshold and reduce the primary side shift ratio of the primary side circuit in the corresponding power conversion unit to reduce the corresponding actual output voltage.
[0116] Step S911: When both actual output voltages are less than or equal to the preset voltage threshold, control both power conversion units to stop working.
[0117] Step S912: Control the switching unit to switch the output states of the two power conversion units according to the state switching command, and control the two power conversion units to work after the switching is completed.
[0118] Understandably, the specific execution process of steps S901-S912 above is described in the relevant description above and will not be repeated here.
[0119] Please continue reading. Figure 10 and Figure 11 , Figure 10 This is a schematic diagram of the actual output voltage curve when the voltage at the output terminal of the power conversion unit corresponding to the power conversion circuit 10 in one embodiment of this application is naturally consumed. Figure 11 This diagram illustrates the actual output voltage curve (curve L111) of the corresponding power conversion unit when the power conversion circuit in one embodiment of this application performs a control method for the power conversion circuit by reducing the primary side inward shift ratio to dissipate energy. Taking a preset voltage threshold of 48 volts as an example... Figure 10 The horizontal time base of the image shown is 5 seconds. Thus, it can be seen that the actual output voltage curve drops from 795V to 15V in approximately 51 seconds. Figure 11 The horizontal time base of the image shown is 100 milliseconds. Thus, it can be seen that the actual output voltage drops from 572V to 44V in approximately 500 milliseconds. Clearly, by implementing the control method of the power conversion circuit provided in this application, rapid energy dissipation can be achieved without setting up a discharge circuit.
[0120] Please see Figure 12 An embodiment of this application also provides a power conversion device 100, including a power conversion circuit 10 and a controller 101. The controller 101 is used to execute the control method of the power conversion circuit as described in any of the above embodiments.
[0121] Please see Figure 13 An embodiment of this application also provides an energy storage device 200, including an energy storage battery 201 and a power conversion device 100 as described above. The energy storage battery 201 is connected to the power conversion device 100 to provide DC power to the power conversion device 100 or to store the DC power output by the power conversion device 100.
[0122] It is understandable that the energy storage device 200 can be a device with pure energy storage function, or it can be an electronic device with energy storage function, such as an air conditioner, refrigerator, or self-moving device with a battery pack.
[0123] Please see Figure 14 An embodiment of this application also provides a control device 300, including a memory 301 and a processor 302. The memory 301 stores a computer program so that when the processor 302 executes the computer program, it implements the control method of the power conversion circuit as described in any of the above embodiments.
[0124] It is understood that the control device 300 can be a standalone electronic device or integrated with the power conversion circuit 10 on the same device. This application does not limit the specific form of the control device 300.
[0125] Please see Figure 15 This application also provides a computer-readable storage medium 400 storing a computer program 401 thereon. When executed by a processor, the computer program 401 implements the control method for the power conversion circuit as described in the above technical solutions. The computer-readable storage medium may be a portable compact disc read-only memory (CD-ROM) and include program code, and may run on a terminal device, such as a personal computer. However, the program product of this invention is not limited thereto. In this document, the readable storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, apparatus, or device.
[0126] It is understood that the controller 101 and processor 302 mentioned in this application may include a microcontroller unit (MCU), a central processing unit (CPU), other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, etc.
[0127] The above-described program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.
[0128] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.
[0129] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.
[0130] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java and C++, and conventional procedural programming languages such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).
[0131] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.
[0132] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A control method for a power conversion circuit, characterized in that, The power conversion circuit includes two power conversion units and a switching unit. Each power conversion unit includes a primary-side circuit and a secondary-side circuit. The switching unit includes a switching switch and is used to control the output terminals of the two power conversion units to be in a series output state or a parallel output state. The method includes: Receive a state switching instruction, the state switching instruction carrying a target output state, wherein the target output state includes the series output state or the parallel output state; When the target output state is inconsistent with the current output state of the two power conversion units, the switching switches of the switching unit are all disconnected and each power conversion unit stops working. The actual output voltages at the output terminals of the two power conversion units are obtained respectively; When the actual output voltage is greater than a preset voltage threshold, the corresponding power conversion unit is activated and the primary side of the primary circuit in the corresponding power conversion unit is shifted inward to reduce the corresponding actual output voltage. When both actual output voltages are less than or equal to the preset voltage threshold, both power conversion units are controlled to stop working. The switching unit is controlled to switch the output states of the two power conversion units according to the state switching command, and the two power conversion units are controlled to work after the switching is completed.
2. The control method according to claim 1, characterized in that, The reduction of the primary-side inward shift of the primary-side circuit in the corresponding power conversion unit to reduce the corresponding actual output voltage includes: According to the preset adjustment step size, the primary side of the primary circuit in the corresponding power conversion unit is shifted inward.
3. The control method according to claim 1, characterized in that, The reduction of the primary-side inward shift of the primary-side circuit in the corresponding power conversion unit to reduce the corresponding actual output voltage includes: The original side inward shift ratio of the corresponding power conversion unit is adjusted to a preset original side inward shift ratio.
4. The control method according to claim 1, characterized in that, The state switching command also carries target electrical parameters. The step of controlling the switching unit to switch the output states of the two power conversion units according to the state switching command, and controlling the two power conversion units to operate after the switching is completed, includes: The switching unit is controlled to operate according to the target output state, so that the output terminals of the two power conversion units are in the target output state; After the output terminals of the two power conversion units are in the target output state, the two power conversion units are controlled to work according to the target electrical parameters.
5. The control method according to claim 4, characterized in that, The switching switch includes a first switch, a second switch, and a third switch. The two power conversion units include a first power conversion unit and a second power conversion unit. The output terminal of the first power conversion unit includes a first positive output terminal and a first negative output terminal. The output terminal of the second power conversion unit includes a second positive output terminal and a second negative output terminal. The first positive output terminal is connected to the second positive output terminal via the first switch, the first negative output terminal is connected to the second negative output terminal via the second switch, and the first negative output terminal is connected to the second positive output terminal via the third switch; The step of controlling the switching switch of the switching unit to operate according to the target output state includes: When the target output state is the parallel output state, control the first switch and the second switch to be turned on, and control the third switch to be turned off; When the target output state is the series output state, the third switch is turned on, and the first switch and the second switch are turned off.
6. The control method according to claim 1, characterized in that, The state switching command also carries target electrical parameters. After receiving the state switching command, the control method further includes: When the target output state is consistent with the current output state, the two power conversion units are controlled to work according to the target electrical parameters.
7. The control method according to claim 4 or 6, characterized in that, The target electrical parameters include the target total output voltage, and the step of controlling the operation of the two power conversion units according to the target electrical parameters includes: The target output voltage of the output terminal of each power conversion unit is determined according to the target output state and the target total output voltage. The power conversion unit is controlled to operate according to the target output voltage.
8. A power conversion device, the power conversion device comprising a power conversion circuit and a controller, characterized in that, The power conversion circuit includes two power conversion units and a switching unit. Each power conversion unit includes a primary circuit and a secondary circuit. The switching unit includes a switching switch. The switching unit is used to control the output terminals of the two power conversion units to be in a series output state or a parallel output state. The controller is used to execute the control method of the power conversion circuit as described in any one of claims 1 to 7.
9. An energy storage device, characterized in that, The energy storage device includes an energy storage battery and a power conversion device as described in claim 8, wherein the energy storage battery is connected to the power conversion device to provide DC power to the power conversion device or to store the DC power output by the power conversion device.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the control method for the power conversion circuit as described in any one of claims 1-7.