Charging and discharging switching method and device of charging and discharging device, terminal and storage medium

Abstract

The application provides a charging and discharging switching method and device of a charging and discharging device, a terminal and a storage medium. The method comprises the following steps: acquiring the working state of a bidirectional DCAC conversion module sent by an AC side control module in real time; if it is monitored that the working state of the bidirectional DCAC conversion module changes, then the driving signals of a bidirectional BUCK-BOOST circuit and an LLC resonant conversion circuit in a first direction are turned off; then the driving signal of the LLC resonant conversion circuit in a second direction is turned on first, and then the driving signal of the LLC resonant conversion circuit in the second direction is turned on; if the first direction is a charging direction, then the second direction is a discharging direction; if the first direction is a discharging direction, then the second direction is a charging direction. Through the above scheme, the application can adopt correct driving timing to switch the state of the charging and discharging device in a dynamic process, so as to avoid the problem of incorrect timing and false triggering of protection.

Description

Technical Field

[0001] This invention relates to the field of charging pile technology, and in particular to a charging and discharging switching method, device, terminal and storage medium for a charging and discharging device. Background Technology

[0002] The charging and discharging device enables bidirectional energy flow between the battery and the power grid, and has two working modes: grid-connected discharge and battery charging. It can achieve stable charging and discharging over a wide voltage range.

[0003] Currently, the charging and discharging modes of charging and discharging devices can only be switched when the device is powered off, and switching states during dynamic processes can easily trigger the protection system erroneously. Summary of the Invention

[0004] In view of this, the present invention provides a charging and discharging switching method, device, terminal and storage medium for a charging and discharging device, which can solve the problem of false triggering protection caused by charging and discharging switching of the charging and discharging device during dynamic processes.

[0005] In a first aspect, embodiments of the present invention provide a charging and discharging switching method for a charging and discharging device. The charging and discharging device includes a bidirectional DC-DC converter module and a bidirectional DC-AC converter module. The bidirectional DC-DC converter module includes a bidirectional BUCK-BOOST circuit and an LLC resonant converter circuit. The first DC side of the bidirectional BUCK-BOOST circuit is used to connect to a DC device. The second DC side of the bidirectional BUCK-BOOST circuit is connected to one end of the LLC resonant converter circuit via a midpoint bus. The other end of the LLC resonant converter circuit is connected to the DC side of the bidirectional DC-AC converter module via a DC bus. The AC side of the bidirectional DC-AC converter module is used to connect to the power grid.

[0006] The method is applied to the DC-side control module, including:

[0007] The operating status of the bidirectional DC-AC conversion module sent by the AC-side control module is obtained in real time.

[0008] If a change in the operating state of the bidirectional DCAC converter module is detected, the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off.

[0009] After turning off the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction, the drive signal of the LLC resonant converter circuit in the second direction is turned on first, and then the drive signal of the bidirectional BUCK-BOOST circuit in the second direction is turned on.

[0010] If the first direction is the charging direction, then the second direction is the discharging direction; if the first direction is the discharging direction, then the second direction is the charging / discharging direction.

[0011] Secondly, embodiments of the present invention provide a charging and discharging switching method for a charging and discharging device. The charging and discharging device includes a bidirectional DC-DC converter module and a bidirectional DC-AC converter module. The bidirectional DC-DC converter module includes a bidirectional BUCK-BOOST circuit and an LLC resonant converter circuit. The first DC side of the bidirectional BUCK-BOOST circuit is used to connect to a DC device. The second DC side of the bidirectional BUCK-BOOST circuit is connected to one end of the LLC resonant converter circuit via a midpoint bus. The other end of the LLC resonant converter circuit is connected to the DC side of the bidirectional DC-AC converter module via a DC bus. The AC side of the bidirectional DC-AC converter module is used to connect to the power grid.

[0012] The method is applied to the AC-side control module, including:

[0013] When a charge / discharge switching command is detected, the loop control setpoint parameters of the bidirectional DC-AC converter module are determined according to the charge / discharge switching command.

[0014] The drive signal of the bidirectional DCAC converter module is generated according to the given parameters of the loop control. The drive signal of the bidirectional DCAC converter module is used to control the switching of the working state of the bidirectional DCAC converter module.

[0015] The operating status of the bidirectional DC-AC converter module is monitored and sent to the DC-side control module, so that when the DC-side control module detects a change in the operating status of the bidirectional DC-AC converter module, it controls the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit to switch their operating states.

[0016] Thirdly, embodiments of the present invention provide a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method as described in any possible implementation of the first or second aspect above.

[0017] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method as described in any possible implementation of the first or second aspect above.

[0018] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0019] The charging / discharging switching method provided in this embodiment of the invention acquires the operating status of the bidirectional DC-AC converter module sent by the AC-side control module in real time. If a change in the operating status of the bidirectional DC-AC converter module is detected, the driving signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off. After turning off the driving signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction, the driving signal of the LLC resonant converter circuit in the second direction is turned on first, followed by the driving signal of the bidirectional BUCK-BOOST circuit in the second direction. Through the above scheme, this embodiment can use the correct driving timing to switch the state of the charging / discharging device in a dynamic process, thereby avoiding the problem of false triggering of protection due to incorrect timing. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the charging and discharging system provided in an embodiment of the present invention;

[0022] Figure 2 This is a flowchart illustrating the implementation of the charge / discharge switching method of the charging / discharge device provided in this embodiment of the invention.

[0023] Figure 3 This is a flowchart illustrating the implementation of the charge / discharge switching method of the charging / discharge device provided in this embodiment of the invention.

[0024] Figure 4 This is a block diagram of the AC side loop control provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the charge / discharge switching device of the charge / discharge apparatus provided in an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the terminal provided in an embodiment of the present invention. Detailed Implementation

[0027] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0029] Figure 1 This is a schematic diagram of the charging and discharging system provided in an embodiment of the present invention. Figure 1 As shown, the charging and discharging system includes a charging and discharging device, a DC-side control module 30, and an AC-side control module 40;

[0030] The charging and discharging device includes a bidirectional DC-DC converter module and a bidirectional DC-AC converter module. The bidirectional DC-DC converter module includes a bidirectional BUCK-BOOST circuit and an LLC resonant converter circuit. The first DC side of the bidirectional BUCK-BOOST circuit is used to connect to DC equipment. The second DC side of the bidirectional BUCK-BOOST circuit is connected to one end of the LLC resonant converter circuit through a midpoint bus. The other end of the LLC resonant converter circuit is connected to the DC side of the bidirectional DC-AC converter module through a DC bus. The AC side of the bidirectional DC-AC converter module is used to connect to the power grid.

[0031] The DC-side control module 30 is used to control the operation of the bidirectional DC-DC converter module 10; the AC-side control module 40 is used to control the operation of the bidirectional DC-AC converter module 20.

[0032] See Figure 2 The flowchart illustrating the charging / discharging switching method of the charging / discharging device provided in this embodiment of the invention is described in detail below:

[0033] S101: Real-time acquisition of the operating status of the bidirectional DC-AC conversion module sent by the AC-side control module.

[0034] In this embodiment, the charging and discharging system may further include a host computer, which can establish a communication connection with either the DC-side control module or the AC-side control module; both the DC-side control module and the AC-side control module can be DSP (Digital Signal Processing) chips. When the host computer establishes a communication connection with the DC-side control module, before S101, the method provided in this embodiment further includes:

[0035] Upon receiving a charge / discharge switching command, the command is sent to the AC-side control module, so that the AC-side control module switches the operating state of the bidirectional DC-AC converter module according to the charge / discharge switching command.

[0036] Specifically, the charge / discharge switching command includes a discharge command that switches the charging / discharge device from a charging state to a discharging state, and a charging command that switches the charging / discharging device from a discharging state to a charging state.

[0037] When the host computer establishes a communication connection with the AC side control module, the DC side control module directly obtains the working status of the bidirectional DC-AC conversion module sent by the AC side control module.

[0038] S102: If a change in the operating state of the bidirectional DCAC converter module is detected, the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off.

[0039] In one embodiment, the specific implementation process of S102 includes:

[0040] If a change in the working state of the bidirectional DC-AC converter module is detected, the DC state machine is controlled to switch to the first state, and when the DC state machine is detected to enter the first state, the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off.

[0041] The first state is the working state corresponding to the first direction, and the DC state machine is a program that controls the working state of the bidirectional DC-DC conversion module.

[0042] In this embodiment, the DC state machine is a program stored in the DC-side control module and used to control the working state of the bidirectional DC-DC converter module. The working states of the DC state machine include initialization state, parameter update state, standby state, power saving state, LLC soft start state, DC-side soft start state, BOOST soft start state, BUCK soft start state, BUCK state, BOOST state, and fault state.

[0043] In existing technologies, to avoid accidental triggering of protection during charge / discharge switching, the DC state machine is typically switched from its current operating state to a standby state first, and then from the standby state to the required operating state, resulting in a relatively long switching time. In this embodiment, when a change in the operating state of the bidirectional DC-AC converter is detected, the DC state machine is directly switched from its current operating state to the required operating state, eliminating the need for a standby transition and thus shortening the charge / discharge switching time.

[0044] Specifically, if the charge / discharge switching command is to switch the charging / discharge device from charging to discharging, the AC side control module controls the bidirectional DC-AC converter module to switch its operating state from charging to discharging. When the DC side control module detects that the bidirectional DC-AC converter module has switched its operating state from charging to discharging, it immediately controls the DC state machine to switch to discharging. When the DC state machine enters the discharging state, it simultaneously shuts down the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the charging direction.

[0045] If the charge / discharge switching command is to switch the charging / discharge device from discharging to charging, the AC side control module controls the bidirectional DC-AC converter module to switch its operating state from discharging to charging. When the DC side control module detects that the bidirectional DC-AC converter module has switched its operating state from discharging to charging, it immediately controls the DC state machine to switch to charging. When the DC state machine enters the charging state, it simultaneously shuts down the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the discharging direction.

[0046] S103: After turning off the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction, first turn on the drive signal of the LLC resonant converter circuit in the second direction, and then turn on the drive signal of the bidirectional BUCK-BOOST circuit in the second direction.

[0047] If the first direction is the charging direction, then the second direction is the discharging direction; if the first direction is the discharging direction, then the second direction is the charging / discharging direction.

[0048] In one embodiment, the operating state includes a discharge state; the specific implementation process of S103 includes:

[0049] If the DC state machine is detected to have entered a discharge state for a first preset time, the drive signal of the LLC resonant converter circuit in the discharge direction is turned on.

[0050] If the DC state machine is detected to have entered a discharge state for a second preset time, the drive signal of the bidirectional BUCK-BOOST circuit in the discharge direction is turned on.

[0051] The second preset time is greater than the first preset time.

[0052] In this embodiment, if the DC state machine is detected to have entered a discharge state for a first preset time, and both the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit are fault-free, then the drive signal of the LLC resonant converter circuit in the discharge direction is turned on. If the DC state machine is detected to have entered a discharge state for a second preset time, the bidirectional BUCK-BOOST circuit is operational, and the DC state machine is currently in a discharge state, then the drive signal of the bidirectional BUCK-BOOST circuit in the discharge direction is turned on.

[0053] In practical applications, when a DC state machine is operating in BOOST state or BOOST soft start state, it can be considered that the DC state machine is currently in a discharging state.

[0054] In one embodiment, the operating state includes a charging state; the specific implementation process of S103 includes:

[0055] If the DC state machine is detected to have entered the charging state for a first preset time, the drive signal of the LLC resonant converter circuit in the charging direction is turned on.

[0056] If the DC state machine is detected to have entered the charging state for a second preset time, the drive signal of the bidirectional BUCK-BOOST circuit in the charging direction is turned on.

[0057] The second preset time is greater than the first preset time.

[0058] In this embodiment, if the DC state machine is detected to have entered the charging state for a first preset time, and both the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit are fault-free, then the drive signal of the LLC resonant converter circuit in the charging direction is turned on. If the DC state machine is detected to have entered the charging state for a second preset time, the bidirectional BUCK-BOOST circuit is operational, and the DC state machine is currently in the charging state, then the drive signal of the bidirectional BUCK-BOOST circuit in the charging direction is turned on.

[0059] In practical applications, when the DC state machine is working in the BUCK state or the BUCK soft start state, it can be considered that the DC state machine is currently in a charging state.

[0060] As can be seen from the above embodiments, in order to prevent the voltage difference between the bus voltage on both sides of the LLC resonant converter circuit and the midpoint bus voltage from being too large, it is necessary to ensure that the drive of the LLC resonant converter circuit is turned on first and the drive of the bidirectional BUCK-BOOST circuit is turned on later during the charging and discharging switching process. Otherwise, it is very easy to cause the system to have problems with the LLC resonant converter circuit hardware overcurrent or midpoint bus overvoltage protection.

[0061] For example, the first preset time can be 1ms, and the second preset time can be 2ms. Taking the switching from charging state to charging state as an example, a specific method for switching charging and discharging timing is as follows:

[0062] 1. When the DC-side control module receives a discharge command from the host computer, it sends the discharge command to the AC-side control module. This communication time is T1. The AC-side control module switches its operating state according to the discharge command and sends the operating state to the DC-side control module. This communication time is T2. When the DC-side control module detects that the bidirectional DC-AC converter module has switched from charging to discharging, it immediately closes the LLC resonant converter module and the bidirectional BUCK-BOOST circuit in the charging direction, and then delays the first preset time T3 to enable the LLC resonant converter module in the discharging direction, and delays the second preset time T4 to enable the bidirectional BUCK-BOOST circuit in the discharging direction. It can be seen that the above timing transformation method does not require shutting down and restarting the device. After receiving the discharge command, only T1+T2+T4 is needed to achieve the transition from charging to discharging, which satisfies the charging / discharging mode switching time requirements and prevents the system from triggering protection during the switching process.

[0063] In one embodiment, the first preset time is determined based on the bus capacitance on the DC bus of the charging and discharging device.

[0064] In this embodiment, during the charging-to-discharging process, there is a short period during which the bidirectional DC-DC converter module is pulse-blocked, while the bidirectional DC-AC converter module is in discharge mode. The duration of this process needs to be evaluated based on the capacity of the bus electrolytic capacitor. It is essential to ensure that the decrease in bus voltage during this period is not lower than a preset voltage threshold; otherwise, switching failure may occur, triggering system fault protection.

[0065] In one embodiment of the present invention, see Figure 3 The diagram illustrates a flowchart of a charging / discharging switching method for another charging / discharging device provided in an embodiment of the present invention. This method is applied to the AC-side control module and is described in detail below:

[0066] The method is applied to the AC-side control module, including:

[0067] When a charge / discharge switching command is detected, the loop control setpoint parameters of the bidirectional DC-AC converter module are determined according to the charge / discharge switching command.

[0068] The drive signal of the bidirectional DCAC converter module is generated according to the given parameters of the loop control. The drive signal of the bidirectional DCAC converter module is used to control the switching of the working state of the bidirectional DCAC converter module.

[0069] The operating status of the bidirectional DC-AC converter module is monitored and sent to the DC-side control module, so that when the DC-side control module detects a change in the operating status of the bidirectional DC-AC converter module, it controls the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit to switch their operating states.

[0070] In this embodiment, the AC-side control module also includes a state machine for controlling the working state of the bidirectional DC-AC converter module. During charging and discharging switching, the AC-side state machine is always in the grid-connected state, the grid-connected relay does not operate, and there is no loop switching involved. It is only necessary to adjust the loop control given parameters to the corresponding working state.

[0071] In one embodiment, the loop control given parameters include a bus voltage given value and a grid-connected current given value;

[0072] The step of generating the drive signal for the bidirectional DC-AC conversion module based on the loop control given parameters includes:

[0073] Obtain the actual value of the DC bus voltage and the actual value of the grid-connected current on the AC side of the bidirectional DC-DC converter module;

[0074] Calculate the voltage loop control quantity based on the given bus voltage value and the actual bus voltage value;

[0075] The larger value between the voltage loop control quantity and the actual value of the grid-connected current is selected as the current loop control quantity.

[0076] Calculate the difference between the current loop control quantity and the grid-connected current setpoint, and use this difference as the target difference. Generate the drive signal for the bidirectional DCAC conversion module based on the target difference.

[0077] In this embodiment, Figure 4 The block diagram of the AC side loop control provided in this embodiment is shown. See [link / reference]. Figure 4 The AC-side control module first acquires the actual values ​​of the bus voltage and grid-connected current. Then, it subtracts the actual bus voltage from the given bus voltage to obtain the bus voltage difference. This difference is input to the first PI controller to obtain the voltage loop control input. The larger of the voltage loop control input and the actual grid-connected current is then selected as the current loop control input. Based on the current loop control input and the given grid-connected current, a target difference is calculated and input to the second PI controller to obtain the duty cycle information of the drive signal. Finally, the drive signal PWM1 for the bidirectional DC-AC converter module is generated based on the duty cycle information. It is evident that the AC-side bus voltage loop output and the given grid-connected current are in a competitive relationship.

[0078] Upon receiving a discharge command, the AC-side control module sets the bus voltage setpoint to the lower limit of the bus voltage, which is less than the actual bus voltage value. Therefore, the bus voltage loop output is always the voltage loop limit value, which can be -100A. At this time, the minimum value in the grid-connected current setpoint range can be set to a value greater than the voltage loop limit value, for example: (-3)A to (-80)A. Therefore, the grid-connected current setpoint serves as the current loop setpoint for grid-connected current loop control. When the actual bus voltage value is lower than the lower limit of the bus voltage, the bus voltage loop is activated to stabilize the bus voltage.

[0079] When a charging command is received, the AC side control module sets the bus voltage setpoint to the bus target value, which can be in the range of 720V to 830V. The grid current setpoint can be assigned a value of -100A. At this time, it is a dual closed-loop control of voltage and current.

[0080] As can be seen from the above embodiments, this embodiment sends the charging and discharging status of the AC-side control module to the DC-side control module. The DC-side control module can accurately determine the state switching time of the bidirectional DC-AC converter module based on its operating status, avoiding the problem of voltage difference between the midpoint bus and the main bus caused by the mismatch between the charging and discharging modes of the DC-side circuit and the AC-side circuit. Furthermore, this embodiment estimates the first preset time using the bus capacitor charge, ensuring that the bus voltage does not drop excessively when the DC-side circuit is blocked and the AC side is in a charging / discharging state; otherwise, switching failure may occur, triggering system fault protection. Further, during charging and discharging switching, the DC side must first activate the CLLC harmonic converter circuit drive, and then activate the bidirectional BUCK-BOOST converter circuit drive; otherwise, inconsistent changes in the midpoint bus and the main bus may occur, easily leading to CLLC hardware overcurrent protection or midpoint bus overvoltage protection at the moment the CLLC harmonic converter circuit drive is activated.

[0081] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0082] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0083] Figure 5 A schematic diagram of the charge / discharge switching device of the charging / discharge apparatus provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below:

[0084] like Figure 5As shown, the charge / discharge switching device 100 for the charge / discharge device applied to the DC-side control module includes:

[0085] The working status acquisition module is used to acquire the working status of the bidirectional DCAC conversion module sent by the AC side control module in real time.

[0086] A drive signal shutdown module is used to shut down the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction if a change in the operating state of the bidirectional DCAC converter module is detected.

[0087] The drive signal activation module is used to first activate the drive signal of the LLC resonant converter in the second direction, and then activate the drive signal of the bidirectional BUCK-BOOST circuit in the second direction after the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter in the first direction are deactivated.

[0088] If the first direction is the charging direction, then the second direction is the discharging direction; if the first direction is the discharging direction, then the second direction is the charging / discharging direction.

[0089] In one embodiment, the drive signal shutdown module includes:

[0090] If a change in the working state of the bidirectional DC-AC converter module is detected, the DC state machine is controlled to switch to the first state, and when the DC state machine is detected to enter the first state, the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off.

[0091] The first state is the working state corresponding to the first direction, and the DC state machine is a program that controls the working state of the bidirectional DC-DC conversion module.

[0092] In one embodiment, the operating state includes a discharge state; the drive signal activation module includes:

[0093] If the DC state machine is detected to have entered a discharge state for a first preset time, the drive signal of the LLC resonant converter circuit in the discharge direction is turned on.

[0094] If the DC state machine is detected to have entered a discharge state for a second preset time, the drive signal of the bidirectional BUCK-BOOST circuit in the discharge direction is turned on.

[0095] The second preset time is greater than the first preset time.

[0096] In one embodiment, the operating state includes a charging state; the drive signal activation module includes:

[0097] If the DC state machine is detected to have entered the charging state for a first preset time, the drive signal of the LLC resonant converter circuit in the charging direction is turned on.

[0098] If the DC state machine is detected to have entered the charging state for a second preset time, the drive signal of the bidirectional BUCK-BOOST circuit in the charging direction is turned on.

[0099] The second preset time is greater than the first preset time.

[0100] In one embodiment, the first preset time is determined based on the bus capacitance on the DC bus of the charging and discharging device.

[0101] In one embodiment, the charge / discharge switching device further includes:

[0102] The instruction sending module is used to send the charge / discharge switching instruction to the AC-side control module when a charge / discharge switching instruction is received, so that the AC-side control module switches the working state of the bidirectional DC-AC converter module according to the charge / discharge switching instruction.

[0103] In one embodiment of the present invention, the charge / discharge switching device for the charge / discharge device applied to the AC side control module includes:

[0104] A given parameter determination module is used to determine the loop control given parameters of the bidirectional DCAC conversion module according to the charge / discharge switching command when a charge / discharge switching command is detected.

[0105] A state switching module is used to generate a drive signal for the bidirectional DCAC converter module based on the given parameters of the loop control. The drive signal for the bidirectional DCAC converter module is used to control the bidirectional DCAC converter module to switch its working state.

[0106] The status transmission module is used to monitor and send the operating status of the bidirectional DC-AC converter module to the DC-side control module, so that when the DC-side control module detects a change in the operating status of the bidirectional DC-AC converter module, it controls the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit to switch their operating states.

[0107] In one embodiment, the loop control given parameters include a bus voltage given value and a grid-connected current given value; the state switching module includes:

[0108] Obtain the actual value of the DC bus voltage and the actual value of the grid-connected current on the AC side of the bidirectional DC-DC converter module;

[0109] Calculate the voltage loop control quantity based on the given bus voltage value and the actual bus voltage value;

[0110] The larger value between the voltage loop control quantity and the actual value of the grid-connected current is selected as the current loop control quantity.

[0111] Calculate the difference between the current loop control quantity and the grid-connected current setpoint, and use this difference as the target difference. Generate the drive signal for the bidirectional DCAC conversion module based on the target difference.

[0112] As can be seen from the above embodiments, this embodiment of the invention acquires the operating status of the bidirectional DC-AC converter module sent by the AC-side control module in real time; if a change in the operating status of the bidirectional DC-AC converter module is detected, the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off; after turning off the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction, the drive signal of the LLC resonant converter circuit in the second direction is turned on first, and then the drive signal of the bidirectional BUCK-BOOST circuit in the second direction is turned on. Through the above scheme, this embodiment can use the correct drive timing to switch the state of the charging and discharging device in a dynamic process, thereby avoiding the problem of false triggering of protection due to incorrect timing.

[0113] Figure 6 This is a schematic diagram of a terminal provided in an embodiment of the present invention. Figure 6 As shown, the terminal 6 in this embodiment includes: a processor 60, a memory 61, and a computer program 62 stored in the memory 61 and executable on the processor 60. When the processor 60 executes the computer program 62, it implements the steps in the charge / discharge switching method embodiments of the various charge / discharge devices described above, for example... Figure 2 Steps 101 to 103 are shown. Alternatively, when the processor 60 executes the computer program 62, it implements the functions of each module / unit in the above-described device embodiments, for example... Figure 5 The functions of modules 110 to 130 are shown.

[0114] For example, the computer program 62 can be divided into one or more modules / units, which are stored in the memory 61 and executed by the processor 60 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 62 in the terminal 6.

[0115] The terminal 6 may include, but is not limited to, a processor 60 and a memory 61. Those skilled in the art will understand that... Figure 6 This is merely an example of terminal 6 and does not constitute a limitation on terminal 6. It may include more or fewer components than shown, or combine certain components, or different components. For example, the terminal may also include input / output devices, network access devices, buses, etc.

[0116] The processor 60 may be a Central Processing Unit (CPU), or 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, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0117] The memory 61 can be an internal storage unit of the terminal 6, such as a hard disk or memory of the terminal 6. The memory 61 can also be an external storage device of the terminal 6, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the terminal 6. Furthermore, the memory 61 can include both internal storage units and external storage devices of the terminal 6. The memory 61 is used to store the computer program and other programs and data required by the terminal. The memory 61 can also be used to temporarily store data that has been output or will be output.

[0118] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0119] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0120] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0121] In the embodiments provided by this invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0122] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0123] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0124] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the charging and discharging switching method embodiments of the various charging and discharging devices described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content contained in the computer-readable medium may be appropriately added to or subtracted from the content as required by the legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium may not include electrical carrier signals and telecommunication signals.

[0125] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for switching between charging and discharging in a charging and discharging device, characterized in that, The charging and discharging device includes a bidirectional DC-DC converter module and a bidirectional DC-AC converter module. The bidirectional DC-DC converter module includes a bidirectional BUCK-BOOST circuit and an LLC resonant converter circuit. The first DC side of the bidirectional BUCK-BOOST circuit is used to connect to DC equipment. The second DC side of the bidirectional BUCK-BOOST circuit is connected to one end of the LLC resonant converter circuit through a midpoint bus. The other end of the LLC resonant converter circuit is connected to the DC side of the bidirectional DC-AC converter module through a DC bus. The AC side of the bidirectional DC-AC converter module is used to connect to the power grid. The method is applied to the DC-side control module, including: The operating status of the bidirectional DC-AC conversion module sent by the AC-side control module is obtained in real time. If a change in the operating state of the bidirectional DCAC converter module is detected, the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off. After turning off the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction, the drive signal of the LLC resonant converter circuit in the second direction is turned on first, and then the drive signal of the bidirectional BUCK-BOOST circuit in the second direction is turned on. If the first direction is the charging direction, then the second direction is the discharging direction; if the first direction is the discharging direction, then the second direction is the charging / discharging direction.

2. The charging / discharging switching method of the charging / discharging device according to claim 1, characterized in that, If a change in the operating state of the bidirectional DC-AC converter module is detected, the driving signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off, including: If a change in the working state of the bidirectional DC-AC converter module is detected, the DC state machine is controlled to switch to the first state, and when the DC state machine is detected to enter the first state, the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction are turned off. The first state is the working state corresponding to the first direction, and the DC state machine is a program that controls the working state of the bidirectional DC-DC conversion module.

3. The charging / discharging switching method of the charging / discharging device according to claim 2, characterized in that, The operating state includes the discharge state; The step of turning off the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction, and then turning on the drive signal of the LLC resonant converter circuit in the second direction, includes: If the DC state machine is detected to have entered a discharge state for a first preset time, the drive signal of the LLC resonant converter circuit in the discharge direction is turned on. If the DC state machine is detected to have entered a discharge state for a second preset time, the drive signal of the bidirectional BUCK-BOOST circuit in the discharge direction is turned on. The second preset time is greater than the first preset time.

4. The charging / discharging switching method of the charging / discharging device according to claim 2, characterized in that, The operating state includes the charging state; The step of turning off the drive signals of the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit in the first direction, and then turning on the drive signal of the LLC resonant converter circuit in the second direction, includes: If the DC state machine is detected to have entered the charging state for a first preset time, the drive signal of the LLC resonant converter circuit in the charging direction is turned on. If the DC state machine is detected to have entered the charging state for a second preset time, the drive signal of the bidirectional BUCK-BOOST circuit in the charging direction is turned on. The second preset time is greater than the first preset time.

5. The charge / discharge switching method of the charge / discharge device according to any one of claims 3 or 4, characterized in that, The first preset time is determined based on the bus capacitor capacity on the DC bus of the charging and discharging device.

6. The charge / discharge switching method of the charge / discharge device according to claim 1, characterized in that, Before acquiring the operating status of the bidirectional DC-AC converter module sent by the AC-side control module in real time, the method further includes: Upon receiving a charge / discharge switching command, the command is sent to the AC-side control module, so that the AC-side control module switches the operating state of the bidirectional DC-AC converter module according to the charge / discharge switching command.

7. A method for switching between charging and discharging in a charging and discharging device, characterized in that, The charging and discharging device includes a bidirectional DC-DC converter module and a bidirectional DC-AC converter module. The bidirectional DC-DC converter module includes a bidirectional BUCK-BOOST circuit and an LLC resonant converter circuit. The first DC side of the bidirectional BUCK-BOOST circuit is used to connect to DC equipment. The second DC side of the bidirectional BUCK-BOOST circuit is connected to one end of the LLC resonant converter circuit through a midpoint bus. The other end of the LLC resonant converter circuit is connected to the DC side of the bidirectional DC-AC converter module through a DC bus. The AC side of the bidirectional DC-AC converter module is used to connect to the power grid. The method is applied to the AC-side control module, including: When a charge / discharge switching command is detected, the loop control setpoint parameters of the bidirectional DC-AC converter module are determined according to the charge / discharge switching command. The drive signal of the bidirectional DCAC converter module is generated according to the given parameters of the loop control. The drive signal of the bidirectional DCAC converter module is used to control the switching of the working state of the bidirectional DCAC converter module. The operating status of the bidirectional DC-AC converter module is monitored and sent to the DC-side control module, so that when the DC-side control module detects a change in the operating status of the bidirectional DC-AC converter module, it controls the bidirectional BUCK-BOOST circuit and the LLC resonant converter circuit to switch their operating states.

8. The charge / discharge switching method of the charge / discharge device according to claim 7, characterized in that, The loop control given parameters include the bus voltage given value and the grid-connected current given value; The step of generating the drive signal for the bidirectional DC-AC conversion module based on the loop control given parameters includes: Obtain the actual value of the DC bus voltage and the actual value of the grid-connected current on the AC side of the bidirectional DC-DC converter module; Calculate the voltage loop control quantity based on the given bus voltage value and the actual bus voltage value; The larger value between the voltage loop control quantity and the actual value of the grid-connected current is selected as the current loop control quantity. Calculate the difference between the current loop control quantity and the grid-connected current setpoint, and use this difference as the target difference. Generate the drive signal for the bidirectional DCAC conversion module based on the target difference.

9. A terminal, characterized in that, It includes a processor and a memory, the memory being used to store a computer program, and the processor being used to call and run the computer program stored in the memory to perform the method as described in any one of claims 1 to 6.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 6 above.

Images