A charging and discharging method of a DC charging and discharging machine and a DC charging and discharging machine

Abstract

The present invention relates to a charging and discharging method and a DC charger / discharger for an electric vehicle, which controls the output power of the power supply module of the working part according to a dispatching instruction; the power supply modules of the hot standby part are in a startup state and operate in a hot standby mode; when receiving an instruction to switch the current direction, the power supply modules of the previous working part are in a startup state and operate in a hot standby mode and become the power supply modules of the hot standby part, and the power supply modules of the previous hot standby part output power in the opposite direction to that of the power supply modules of the previous working part according to the dispatching instruction and become the power supply modules of the working part. By setting different state modes for the power supply modules of the working part and the hot standby part, the switching between charging and discharging of the electric vehicle can be completed according to the regulation instruction, not only without the operation of turning off the power supply module, but also with a fast switching speed and convenient operation, thus realizing efficient vehicle-grid interaction.

Description

Technical Field

[0001] The present invention relates to a charging and discharging method for a DC charger and a DC charger, belonging to the field of chargers. Background Art

[0002] With the development and standard improvement of electric vehicles, more and more electric vehicles support the discharging function, which promotes large-scale participation of electric vehicles in vehicle-grid interaction as an important path for the development of future virtual power plants. The rapid switching of charging and discharging of electric vehicles will help to quickly respond to the dispatching requirements of the power grid, enabling electric vehicles to better participate in vehicle-grid interaction.

[0003] The key device in vehicle-grid interaction is the charger. In the published text of the patent application with the application publication number CN103354381A, an electric vehicle charger is disclosed. Among them, the power conversion system can complete the mutual conversion between alternating current and direct current. The control system in the charger completes the charging of the electric vehicle and the discharging and grid connection of the power battery through communication interaction with the human-machine interface and the remote terminal. Specifically: after the charging and discharging plug is connected to the power battery, the charging operation is started (after setting the charging parameters by starting the charger, there will be a charging mode prompt on the display screen, and you can select your suitable mode among the constant charge amount, constant time, automatic full charge and other modes; click OK to start the device to start charging; after charging is completed, the charging and discharging plug can be disconnected; if you want to terminate charging midway, you need to manually terminate charging or send a termination charging command by the monitoring background or the remote end, and the charging and discharging plug can be disconnected after charging is terminated). After the charging and discharging plug is connected to the power battery, the discharging operation is started (start the charger, set the discharging parameters, and the charger sends a discharging request; the monitoring background or the remote terminal sends a discharging or grid connection command to the charger according to the power grid situation; the charger automatically discharges or is connected to the grid according to the command of the monitoring background or the remote terminal; after discharging stops, other operations can be performed). Obviously, when switching between charging and discharging of the charger each time, not only is the operation troublesome, the intelligent charging and discharging state cannot be realized, but also the conversion time of the charging and discharging state is prolonged, which is not conducive to the development of vehicle-grid interaction.

[0004] At the same time, in the existing charger of electric vehicles, multiple power modules are used in parallel to achieve high-power output. When switching between charging and discharging, due to the characteristic requirements of the power modules, the power modules need to be shut down and then restarted. There is an obvious breakpoint in the power transmission, and the overall switching speed is slow, which can only meet the scenarios with relatively weak real-time requirements for charging and discharging switching. Summary of the Invention

[0005] The purpose of the present invention is to provide a charging and discharging method for a DC charger and a DC charger, which is used to solve the problem of slow response speed of charging and discharging switching of electric vehicles, and realize fast and efficient charging and discharging switching of electric vehicles, so as to promote the interaction between electric vehicles and the power grid.

[0006] To achieve the above object, on the one hand, the present invention provides a charging and discharging method for a DC charging and discharging machine, including:

[0007] Controlling the output power of the power module of the working part according to the scheduling instruction; the power module of the hot standby part is in the startup state and operates in the hot standby mode;

[0008] After receiving the instruction to switch the current direction, the power module of the previous working part is in the startup state and operates in the hot standby mode and becomes the power module of the hot standby part, and the power module of the previous hot standby part outputs power in the opposite direction to that of the power module of the previous working part according to the scheduling instruction and becomes the power module of the working part;

[0009] The power module is used for rectifying to output power in the way of charging the vehicle and / or for inverting to output power in the way of discharging the vehicle and transmitting power to the power grid.

[0010] Further, in the above charging and discharging method of the DC charging and discharging machine, the hot standby mode includes a standby state with zero output power.

[0011] Further, in the above charging and discharging method of the DC charging and discharging machine, the hot standby mode includes outputting power in the opposite direction to that of the power module of the working part, and the output power is equal to the actual power of the power module of the working part minus the required power of the power module.

[0012] Further, the above charging and discharging method of the DC charging and discharging machine further includes:

[0013] Within a preset time before switching the current direction, according to the scheduling instruction, set the output total power ratio of the power module of the working part to the power module of the hot standby part to 2:1, adjust the output power of the power module of the hot standby part according to the scheduling instruction to reach the target required power after switching the current direction, and adjust the output power of the power module of the working part to twice the target required power;

[0014] After receiving the instruction to switch the current direction, switch the power module of the previous working part to a standby state with zero output power and become the power module of the hot standby part; the power module of the previous hot standby part maintains the current target required power and becomes the power module of the working part.

[0015] Further, in the above charging and discharging method of the DC charging and discharging machine, the output power of the power module of the hot standby part reaches the target required power after switching the current direction and the output power of the power module of the working part is adjusted to twice the target required power by the way of increasing the current step by step.

[0016] On the other hand, the present invention also provides a DC charging and discharging machine, which includes a controller and at least two power modules. The controller executes instructions for implementing the following method steps:

[0017] Control the output power of the power modules in the working part according to the scheduling instruction; the power modules in the hot standby part are in the startup state and operate in the hot standby mode;

[0018] After receiving the instruction to switch the current direction, the power modules in the previous working part are in the startup state and operate in the hot standby mode and become the power modules in the hot standby part. The power modules in the previous hot standby part output power in the opposite direction to that of the power modules in the previous working part according to the scheduling instruction and become the power modules in the working part;

[0019] The power module is used to rectify and output power in the way of charging the vehicle and / or is used to invert and output power in the way of discharging the vehicle and transmitting power to the power grid.

[0020] Further, in the above DC charging and discharging machine, the hot standby mode includes a standby state with zero output power.

[0021] Further, in the above DC charging and discharging machine, the hot standby mode includes outputting power in the opposite direction to that of the power modules in the working part, and the output power is equal to the actual power of the power modules in the working part minus the required power of the power module.

[0022] Further, in the above DC charging and discharging machine, it also includes performing the following method steps: within a preset time before switching the current direction, set the ratio of the total output power of the power modules in the working part to the power modules in the hot standby part to 2:1 according to the scheduling instruction, adjust the output power of the power modules in the hot standby part according to the scheduling instruction to reach the target required power after switching the current direction, and adjust the output power of the power modules in the working part to twice the target required power;

[0023] After receiving the instruction to switch the current direction, switch the power modules in the previous working part to the standby state with zero output power and become the power modules in the hot standby part; the power modules in the previous hot standby part maintain the current target required power and become the power modules in the working part.

[0024] Further, in the above DC charging and discharging machine, the output power of the power modules in the hot standby part reaches the target required power after switching the current direction and the output power of the power modules in the working part is adjusted to twice the target required power by means of stepwise increasing the current.

[0025] The beneficial effects of the present invention are as follows: controlling the output power of the power supply module of the working part according to the dispatching instruction; the power supply module of the hot standby part is in the startup state and operates in the hot standby mode; when receiving the instruction to switch the current direction, the power supply module of the previous working part is in the startup state and operates in the hot standby mode and becomes the power supply module of the hot standby part, and the power supply module of the previous hot standby part outputs power in the direction opposite to that of the power supply module of the previous working part according to the dispatching instruction and becomes the power supply module of the working part; the power supply module is used for rectifying to output power in the way of charging the vehicle and / or for inverting to output power in the way of discharging the vehicle to transmit power to the power grid. By setting different state modes for the power supply module of the working part and the power supply module of the hot standby part, the switching between charging and discharging of the electric vehicle is completed according to the regulation instruction, which not only does not require operations such as turning off the power supply module, but also has a fast switching speed and is easy to operate, so as to efficiently carry out vehicle-grid interaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 FIG. is a schematic flow chart of the charging and discharging method of a DC charger and discharger in an actual application scenario according to one aspect of the present invention;

[0027] Figure 2 FIG. is a structural diagram of a DC charger and discharger in an actual application scenario according to another aspect of the present invention;

[0028] Among them, the reference numerals are:

[0029] AC: AC power grid; F1: charging operation platform; F2: virtual power plant dispatching platform; EV1, EV2: electric vehicles;

[0030] K1: control module; M1: AC / DC bidirectional power supply module (working part module of charging gun 1); M1`: AC / DC bidirectional power supply module (hot standby part module of charging gun 1); M2: AC / DC bidirectional power supply module (working part module of charging gun 2); M2`: AC / DC bidirectional power supply module (hot standby part module of charging gun 2); D: power distribution module; P0: AC watt-hour meter; P1: DC watt-hour meter of charging gun 1; P2: DC watt-hour meter of charging gun 2; C1: charging gun 1; C2: charging gun 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to make the purpose, technical solution and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0032] The concept of the invention is that in order to accelerate the switching speed between charging and discharging of the DC charging and discharging machine, the power supply module is divided into a working part and a hot standby part, so as to cleverly convert the switching between charging and discharging into the switching between the working part and the hot standby part, without waiting for the charging and discharging machine to respond, and efficiently complete the switching between charging and discharging, providing efficient and stable transmission conditions for the interaction between electric vehicles and the power grid.

[0033] Method Embodiment 1:

[0034] A charging and discharging method for a DC charging and discharging machine according to one aspect of the present invention, wherein the method includes steps S11 - S12, specifically:

[0035] Connect the periphery of the DC charging and discharging machine to the power grid, the operation management platform, the virtual power plant platform and at least one electric vehicle. Among them, the virtual power plant platform sets and issues dispatching instructions according to the needs of different users or different power plants. Among them, the dispatching instructions include but are not limited to the current working direction, the output power of the DC charging and discharging machine equipment, and the dispatching time, etc.

[0036] After the virtual power plant platform issues a dispatching instruction, in step S11, control the output power of the power supply module of the working part according to the dispatching instruction; the power supply module of the hot standby part is in a startup state and operates in the hot standby mode, wherein the power supply module is used for rectifying to output power in the way of charging the vehicle and / or for inverting to output power in the way of discharging the vehicle to transmit power to the power grid.

[0037] Here, the power supply directions provided by the power supply module of the working part and the power supply module of the hot standby part are opposite to each other. For example: the power supply module of the working part is the power supply module that meets the current charging demand of the electric vehicle, while the power supply module of the hot standby part is the power supply module for the discharging demand opposite to the current charging demand of the electric vehicle.

[0038] At the same time, in the actual application scenario, the power supply module includes at least two AC / DC bidirectional power supply modules, and the AC / DC bidirectional power supply modules can operate in parallel; divide the working part and the hot standby part by controlling the current direction of each AC / DC bidirectional power supply module. Of course, the same AC / DC bidirectional power supply module can be used as the working part or the hot standby part under different division situations to realize that the power supply module is used for rectifying and / or for inverting.

[0039] In step S12, when receiving the instruction to switch the current direction, the power supply module of the previous working part is in a startup state and operates in the hot standby mode and becomes the power supply module of the hot standby part, and the power supply module of the previous hot standby part outputs power in the opposite direction to that of the previous power supply module of the working part according to the dispatching instruction and becomes the power supply module of the working part.

[0040] Through steps S11 - S12, by using the division of different power modules, the operating state conversion between the working part and the standby part is directly carried out to achieve the charge - discharge switching of the electric vehicle. And during the switching process, there is no need to wait or perform other operations, which speeds up the charge - discharge switching speed and is conducive to the vehicle - grid interaction after the electric vehicle is connected to the grid, so as to improve user satisfaction.

[0041] The present application provides a preferred embodiment of a charge - discharge method for a DC charger. First, it is preferred that the scheduling instruction issued by the virtual power plant platform is: at time T1, switch the current working direction of electric vehicle Car1 from charging to discharging; it is preferred that the AC / DC bidirectional power module in the working part provides the charging demand. Since the power directions provided by the power modules in the working part and the standby part are opposite to each other, it is preferred that the AC / DC bidirectional power module in the standby part provides the discharging demand. According to the scheduling instruction, control the AC / DC bidirectional power module in the working part to output power to charge electric vehicle Car1, and control the AC / DC bidirectional power module in the standby part to start and work in the standby state. When reaching time T1, convert the previous AC / DC bidirectional power module in the working part to the standby state and make it the AC / DC bidirectional power module in the standby part; the previous AC / DC bidirectional power module in the standby part starts to discharge electric vehicle Car1 and becomes the AC / DC bidirectional power module in the working part.

[0042] Method Embodiment 2:

[0043] Following the above - mentioned embodiment of the present application, in a charge - discharge method for a DC charger provided by the present application, the standby mode includes a standby state with zero output power. At the same time, in the embodiments of the present application, the output power of the power module is adjusted by adjusting the current.

[0044] The present application provides a preferred embodiment of a charge - discharge method for a DC charger. It is preferred that the virtual power plant platform issues a control instruction of "at time T2, electric vehicle Car2 needs to switch from charging 20kW to discharging 20kW"; according to the control instruction, the AC / DC bidirectional power module in the working part provides an output current that meets the charging demand of 20kW for electric vehicle Car2, and the AC / DC bidirectional power module in the standby part starts but sets the output current to 0, so that the AC / DC bidirectional power module in the standby part is in the standby state; when reaching time T2, the previous AC / DC bidirectional power module in the working part starts but the output current is 0, and at the same time becomes the AC / DC bidirectional power module in the standby part, so that the previous AC / DC bidirectional power module in the working part is in standby; the previous AC / DC bidirectional power module in the standby part provides an output current that meets the discharging demand of 20kW for electric vehicle Car2, and at the same time becomes the AC / DC bidirectional power module in the working part.

[0045] Method Embodiment 3:

[0046] Continuing with the above embodiments of the present application, in a charging and discharging method of a DC charger provided by the present application, the hot standby mode includes outputting power in a direction opposite to that of the power supply module of the working part, and the output power is equal to the actual power of the power supply module of the working part minus the required power of the power supply module.

[0047] Here, within a preset time before switching the current direction, according to the scheduling instruction, the total output power ratio of the power supply module of the working part to the power supply module of the hot standby part is set to 2:1. According to the scheduling instruction, the output power of the power supply module of the hot standby part is adjusted to reach the target required power after switching the current direction, and the output power of the power supply module of the working part is adjusted to twice the target required power. Here, the target required power refers to the total output power of the final DC charger.

[0048] Among them, by increasing the current step by step, the output power of the power supply module of the hot standby part reaches the target required power after switching the current direction, and the output power of the power supply module of the working part is adjusted to twice the target required power, so as to achieve a total power ratio of 2:1, and part of the output current of the working part cancels out the output current of the hot standby part, ensuring that the electric vehicle is still in the state corresponding to the working part.

[0049] Here, the preset time is set according to different electric vehicle requirements, etc., so as to complete the setting of the total power ratio before the time of reaching the switching current direction.

[0050] When receiving the instruction to switch the current direction, the power supply module of the previous working part is switched to a standby state with zero output power and becomes the power supply module of the hot standby part; the power supply module of the previous hot standby part maintains the current target required power and becomes the power supply module of the working part.

[0051] The present application provides a preferred embodiment of a charging and discharging method of a DC charger. Preferably, the scheduling instruction issued by the virtual power plant platform is: at time T3, electric vehicle Car3 needs to switch from charging 20kW to discharging 20kW. According to the scheduling instruction, within the preset time before time T3 is reached, the total output power ratio of the AC / DC bidirectional power supply module of the working part to the AC / DC bidirectional power supply module of the hot standby part is set to 2:1. Specifically: by adjusting the output current of the AC / DC bidirectional power supply module of the working part in steps of 1-5A to be twice the output current of the AC / DC bidirectional power supply module of the hot standby part (i.e., I 工作 =2I 需求 ), and by adjusting the output current of the AC / DC bidirectional power supply module of the hot standby part in steps of 1-5A to be I 需求, so that the output current of the working part cancels out the output current of the standby part, ensuring that the working part provides a charging current of 20 kW for the electric vehicle Car3. When reaching time T3, the output current of the AC / DC bidirectional power supply module of the previous working part is 0, that is, there is no charging current, and it becomes the AC / DC bidirectional power supply module of the standby part; the AC / DC bidirectional power supply module of the previous standby part provides a discharging current of 20 kW and becomes the AC / DC bidirectional power supply module of the working part.

[0052] Method Embodiment 4:

[0053] In the DC charger / discharger in the actual application scenario, when the standby mode is set to the standby state with zero output power, it enters the normal standby state; when the standby mode is set to output power in the opposite direction to the power supply module of the working part, it enters the enhanced standby state. And it is default that the charger / discharger enters the normal standby state when starting up.

[0054] As Figure 1 shown, it is a schematic flowchart of the charging and discharging method of a DC charger / discharger according to an aspect of the present invention in the actual application scenario. Among them, after the charger / discharger is connected to the electric vehicle and outputs normally, it is default set to the normal standby state, that is, the standby mode is the standby state with zero output power, and the total power ratio of the working part and the standby part is set to 1:1. It is judged whether the control module receives the scheduling instruction issued by the virtual power plant platform. If not, the current normal standby state is maintained.

[0055] If so, it is selected whether to continue in the normal standby state. If so, in the normal standby mode, the output current of the power supply module of the working part is controlled to be 0, the output current of the power supply module of the standby part is set to the target demand current in the scheduling instruction, and the working part module and the standby part module are interchanged.

[0056] If not, it is switched to the enhanced standby mode, the current magnitude is adjusted according to the scheduling instruction, and it is judged whether it reaches 90 s before the time to switch the current direction. If not, the current magnitude is continuously adjusted; if so, the total power ratio of the power supply module of the working part and the power supply module of the standby part is set to 2:1. The output current of the standby part module starts from 0 and increases to the target demand current in steps of 1 - 5 A (select an appropriate current value according to the actual situation), and at the same time, the output current of the power supply module of the working part increases (in steps of 1 - 5 A) to 2 times the target demand current to complete the preparation for the enhanced standby mode. When reaching the time to switch the current direction, the current direction is immediately switched, that is, the power supply module of the working part enters standby, that is, the output current of the working part is 0, the output current of the power supply module of the standby part is set to the target demand current, and the working part and the standby part are interchanged.

[0057] Enhance the hot standby state. Utilize the redundant power modules of the DC charger / discharger to set the current of the hot standby part to the reverse of the current direction of the current demand, and gradually increase the reverse output power to make the hot standby modules in the high-power output state. When the current changes, seamless switching can be achieved, saving the time required for the output current to rise and quickly responding to the regulation instructions of the virtual power plant platform.

[0058] The number of power modules in the working part and the hot standby part can both be adjusted according to the actual situation, and can be set to the hybrid hot standby mode according to the specific application scenario, that is, part of the output power of the hot standby part can be 0, and the output power of the other part is greater than 0. Achieve a balance between energy saving and quick response.

[0059] Embodiment 1 of the DC charger / discharger:

[0060] As Figure 2 shown, it is a structural diagram of a DC charger / discharger in an actual application scenario according to another aspect of the present invention. Among them, the DC charger / discharger includes a control module K1, a power distribution module D, an AC / DC bidirectional power module array (M1, M1`, M2, M2`, where M1: AC / DC bidirectional power module, that is, the working part module of charging gun 1; M1`: AC / DC bidirectional power module, that is, the hot standby part module of charging gun 1; M2: AC / DC bidirectional power module, that is, the working part module of charging gun 2; M2`: AC / DC bidirectional power module, that is, the hot standby part module of charging gun 2), a metering module (P0 - P2, where P0: AC energy meter; P1: DC energy meter of charging gun 1; P2: DC energy meter of charging gun 2;), charging guns (C1, C2), etc. The control module has a built-in current quick switching algorithm and control logic. The periphery of the DC charger / discharger includes an AC power grid AC, a charging operation platform F1, a virtual power plant dispatching platform F2, electric vehicles (EV1, EV2), etc.

[0061] The metering module is divided into an AC metering module and a DC metering module. The AC metering module P0 is used to measure parameters such as the AC side charging and discharging electric energy, voltage, current, and power of the DC charger / discharger. The DC metering modules (P1, P2) correspond one-to-one with the charging guns (C1, C2) and are used to measure parameters such as the DC input and output electric energy, voltage, current, and power of each charging gun.

[0062] The AC / DC bidirectional power module array includes multiple AC / DC bidirectional power modules. The AC / DC bidirectional power modules can operate in parallel. The control module K1 distributes AC / DC bidirectional power modules to each charging gun by controlling the switch matrix in the power distribution module D (distributing C1 to M1 and M1'; distributing C2 to M2 and M2'), and sets these bidirectional power modules into a working part and a hot standby part. Among them, the power modules in the working part output according to the current demand directions of the electric vehicle EV1 and the electric vehicle EV2, the working direction of the power modules in the hot standby part is set to be reverse, and they are set to the startup state.

[0063] The DC charging and discharging machine is designed with two hot standby modes: ordinary hot standby and enhanced hot standby. Among them, in the ordinary hot standby mode, the output power of the power modules in the working part is the vehicle demand power of the electric vehicle EV1 and the electric vehicle EV2, the power of the power modules in the hot standby part is 0, and the module ratio of the working part to the hot standby part is 1:1. In the enhanced hot standby mode, the total power ratio of the working part to the hot standby part is preferably 2:1, and this total power ratio can be set according to different requirements. The ordinary hot standby mode shortens the switching time of the charging and discharging current direction to within 3 s, and the enhanced hot standby mode shortens the switching time of the charging and discharging current direction to within 100 ms.

Claims

1. A charging and discharging method for a DC charging and discharging machine, characterized in that: include: The output power of the power module of the working part is controlled according to the dispatching instruction; the power module of the hot standby part is in the startup state and works in the hot standby mode; Within a preset time before switching the current direction, the output power of the power module of the working part and the power module of the hot standby part are adjusted according to the scheduling instruction, and the output power of the power module of the hot standby part is adjusted in the opposite direction of the power module of the working part according to the scheduling instruction to reach the target required power after switching the current direction; When receiving the instruction to switch the current direction, the power module of the working part is in the startup state and works in the hot standby mode with zero output power and becomes the power module of the hot standby part, and the power module of the hot standby part maintains the current target required power and becomes the power module of the working part; The power module is used for rectifying to output power in a manner of charging the vehicle and / or for inverting to output power in a manner of discharging the vehicle and transmitting power to the power grid.

2. The charging and discharging method of a DC charger and discharger according to claim 1, characterized in that: Also includes: Within a preset time before switching the current direction, according to the scheduling instruction, the total output power ratio of the power module of the working part and the power module of the hot standby part is set to 2:1, and according to the scheduling instruction, the output power of the power module of the hot standby part is adjusted to reach the target required power after switching the current direction, and the output power of the power module of the working part is adjusted to twice the target required power; When receiving the instruction to switch the current direction, the power module of the previous working part is switched to the standby state with zero output power and becomes the power module of the hot standby part; the power module of the previous hot standby part maintains the current target demand power and becomes the power module of the working part.

3. The charging and discharging method of a DC charger and discharger according to claim 2, characterized in that: By increasing the current in steps, the output power of the power module of the hot standby part reaches the target required power after switching the current direction, and the output power of the power module of the working part is adjusted to twice the target required power.

4. A DC charging and discharging machine, characterized in that: The invention comprises a controller and at least two power supply modules, wherein the controller executes instructions for implementing the following method steps: The output power of the power module of the working part is controlled according to the dispatching instruction; the power module of the hot standby part is in the startup state and works in the hot standby mode; Within a preset time before switching the current direction, the output power of the power module of the working part and the power module of the hot standby part are adjusted according to the scheduling instruction, and the output power of the power module of the hot standby part is adjusted in the opposite direction of the power module of the working part according to the scheduling instruction to achieve the target required power after switching the current direction; When receiving the instruction to switch the current direction, the power module of the working part is in the startup state and works in the hot standby mode with zero output power and becomes the power module of the hot standby part, and the power module of the hot standby part maintains the current target required power and becomes the power module of the working part; The power module is used for rectifying to output power in a manner of charging the vehicle and / or for inverting to output power in a manner of discharging the vehicle and transmitting power to the power grid.

5. The DC charger and discharger according to claim 4, characterized in that: Also includes: Within a preset time before switching the current direction, according to the scheduling instruction, the total output power ratio of the power module of the working part and the power module of the hot standby part is set to 2:1, and according to the scheduling instruction, the output power of the power module of the hot standby part is adjusted to reach the target required power after switching the current direction, and the output power of the power module of the working part is adjusted to twice the target required power; When receiving the instruction to switch the current direction, the power module of the previous working part is switched to the standby state with zero output power and becomes the power module of the hot standby part; the power module of the previous hot standby part maintains the current target demand power and becomes the power module of the working part.

6. The DC charger and discharger according to claim 5, characterized in that: By increasing the current in steps, the output power of the power module of the hot standby part reaches the target required power after switching the current direction, and the output power of the power module of the working part is adjusted to twice the target required power.

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