Bus voltage control method, control module and system for charging and discharging device

Abstract

The present invention provides a bus voltage control method, control module and system for a charging and discharging device, the method comprising: obtaining a first bus voltage lower limit value sent by an AC side control module; if the charging and discharging device is in a charging state, calculating a second bus voltage lower limit value based on a charging target value of a DC device; selecting a larger value from the first and second bus voltage lower limits as the first bus voltage target value and sending it to the AC side control module, so that the AC side control module performs loop control on the DC bus voltage; if the charging and discharging device is in a discharging state, calculating a third bus voltage lower limit value according to the actual voltage of the DC device; and selecting a larger value from the first and third bus voltage lower limits as the second bus voltage target value to perform loop control on the DC bus voltage. Through the above scheme, the present application can simultaneously meet the minimum modulation ratio requirement and the system efficiency index requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of charge and discharge control, and in particular to a bus voltage control method, a control module and a system for a charge and discharge device. Background Art

[0002] The charging and discharging device model can realize the two-way flow of energy between the battery side and the grid side. It has two working modes: grid-connected discharge and battery charging, and can achieve stable charging and discharging in a wide voltage range.

[0003] In order to meet the minimum modulation ratio requirement when the battery side voltage is high or the grid side voltage is high when the charging and discharging device is working normally, the bus voltage of the charging and discharging device is usually controlled to be relatively high within the full voltage range in the prior art. However, this will result in low system efficiency and fail to meet the system efficiency index requirements. Summary of the invention

[0004] In view of this, the present invention provides a bus voltage control method, control module and system for a charging and discharging device, which can solve the problem that the minimum modulation ratio requirement and the system efficiency index requirement cannot be met simultaneously when controlling the bus voltage.

[0005] In a first aspect, an embodiment of the present invention provides a bus voltage control method for a charging and discharging device, wherein the charging and discharging device includes a bidirectional DCDC conversion module and a bidirectional DCAC conversion module, wherein a first DC side of the bidirectional DCDC conversion module is used to connect a DC device; a second DC side of the bidirectional DCDC conversion module is connected to a DC side of the bidirectional DCAC conversion module through a DC bus, and an AC side of the bidirectional DCAC conversion module is used to connect a power grid;

[0006] The method is applied to a DC side control module, comprising:

[0007] Obtaining a first bus voltage lower limit value sent by an AC side control module, where the first bus voltage lower limit value is a voltage lower limit value corresponding to the DC bus, and the first bus voltage lower limit value is calculated based on voltage data of the power grid;

[0008] If the charging and discharging device is in a discharging state, the second bus voltage lower limit value is calculated according to the actual voltage of the DC device; the larger value of the first bus voltage lower limit value and the second bus voltage lower limit value is used as the first bus voltage target value; and the voltage of the DC bus is loop-controlled based on the first bus voltage target value;

[0009] If the charging and discharging device is in a charging state, the third bus voltage lower limit value is calculated based on the charging target value of the DC device, and the larger value of the first bus voltage lower limit value and the third bus voltage lower limit value is used as the second bus voltage target value; and the second bus voltage target value is sent to the AC side control module, so that the AC side control module performs loop control on the voltage of the DC bus according to the second bus voltage target value.

[0010] In a second aspect, an embodiment of the present invention provides a bus voltage control method for a charging and discharging device, wherein the charging and discharging device includes a bidirectional DCDC conversion module and a bidirectional DCAC conversion module, wherein a first DC side of the bidirectional DCDC conversion module is used to connect a DC device; a second DC side of the bidirectional DCDC conversion module is connected to a DC side of the bidirectional DCAC conversion module through a DC bus, and an AC side of the bidirectional DCAC conversion module is used to connect a power grid;

[0011] The method is applied to an AC side control module, comprising:

[0012] Acquiring voltage data of the power grid, wherein the voltage data of the power grid includes an effective value of a power grid line voltage and an instantaneous value of a power grid line voltage;

[0013] Calculating a first bus voltage value based on the grid line voltage effective value and the topological parameters of the bidirectional DCAC conversion circuit;

[0014] Selecting the larger value of the first bus voltage value and the instantaneous value of the grid line voltage as the first bus voltage lower limit value;

[0015] Sending the first bus voltage lower limit value to a DC side control module, so that the DC side control module calculates a second bus voltage target value when the charging and discharging device is in a charging state according to the first bus voltage lower limit value;

[0016] The second bus voltage target value sent by the DC side control module is obtained, and the voltage of the DC bus is loop-controlled according to the second bus voltage target value.

[0017] In a third aspect, an embodiment of the present invention provides a DC side control module, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method described in any possible implementation manner of the first aspect are implemented.

[0018] In a fourth aspect, an embodiment of the present invention provides an AC side control module, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method described in any possible implementation manner of the second aspect above are implemented.

[0019] In a fifth aspect, an embodiment of the present invention provides a charging and discharging system, comprising a charging and discharging device, a DC side control module as described in the third aspect above, and an AC side control module as described in the fourth aspect above;

[0020] The charging and discharging device comprises a bidirectional DCDC conversion module and a bidirectional DCAC conversion module, wherein the first DC side of the bidirectional DCDC conversion module is used to connect a DC device; the second DC side of the bidirectional DCDC conversion module is connected to the DC side of the bidirectional DCAC conversion module through a DC bus, and the AC side of the bidirectional DCAC conversion module is used to connect to a power grid;

[0021] The DC side control module is used to control the operation of the bidirectional DCDC conversion module;

[0022] The AC side control module is used to control the operation of the bidirectional DCAC conversion module.

[0023] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0024] The embodiment of the present invention first obtains a first bus voltage lower limit value sent by an AC side control module, and the first bus voltage lower limit value is calculated based on the voltage data of the power grid; if the charging and discharging device is in a discharging state, the second bus voltage lower limit value is calculated according to the actual voltage of the DC device; the larger value of the first bus voltage lower limit value and the second bus voltage lower limit value is used as the first bus voltage target value; the voltage of the DC bus is loop-controlled based on the first bus voltage target value; if the charging and discharging device is in a charging state, the third bus voltage lower limit value is calculated based on the charging target value of the DC device, and the larger value of the first bus voltage lower limit value and the third bus voltage lower limit value is used as the second bus voltage target value; and the second bus voltage target value is sent to the AC side control module, so that the AC side control module performs loop control on the voltage of the DC bus according to the second bus voltage target value. Through the above scheme, this embodiment can comprehensively consider the wide voltage range of the grid side and the DC side, and coordinate the bus voltage target values ​​during the charging process and the discharging process, so as to meet the normal operation of the system topology within a wide voltage range and the high-efficiency control requirements of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 This is an application scenario diagram of the bus voltage control method of the charging and discharging device provided by an embodiment of the present invention;

[0027] Figure 2 is a flow chart of the implementation of the bus voltage control method of the charging and discharging device provided by the embodiment of the present invention;

[0028] Figure 3 is an interactive flow chart of a bus voltage control method of a charging and discharging device provided in an embodiment of the present invention;

[0029] Figure 4 It is a schematic diagram of an AC side control module / DC side control module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0032] Figure 1 This is an application scenario diagram of the bus voltage control method for a charging and discharging device provided by 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;

[0033] The charging and discharging device includes a bidirectional DCDC conversion module 10 and a bidirectional DCAC conversion module 20, wherein the first DC side of the bidirectional DCDC conversion module 10 is used to connect a DC device; the second DC side of the bidirectional DCDC conversion module 10 is connected to the DC side of the bidirectional DCAC conversion module 20 through a DC bus, and the AC side of the bidirectional DCAC conversion module 10 is used to connect to a power grid;

[0034] The DC side control module 30 is used to control the operation of the bidirectional DCDC conversion module 10;

[0035] The AC side control module 40 is used to control the operation of the bidirectional DCAC conversion module 20 .

[0036] See also Figure 2 , which shows a flow chart of the implementation of the bus voltage control method of the charging and discharging device provided by the embodiment of the present invention. The execution subject of the method is the DC side control module, and the process is described in detail as follows:

[0037] S101: Acquire a first bus voltage lower limit value sent by an AC side control module, where the first bus voltage lower limit value is a voltage lower limit value corresponding to the DC bus, and the first bus voltage lower limit value is calculated based on voltage data of the power grid.

[0038] In this embodiment, based on the above circuit topology, it can be seen that the AC side control module of the charging and discharging device controls the voltage of the DC bus based on the grid voltage data in the charging state, and the DC side control module controls the voltage of the DC bus based on the voltage data of the DC device in the discharging state. Therefore, in order for the DC side control module to refer to the grid voltage data when controlling the DC bus, the DC side control module needs to receive the first bus voltage lower limit value calculated from the grid voltage data and sent by the AC side control module.

[0039] Specifically, the DC side control module obtains the first bus voltage lower limit value calculated by the AC side control module based on the grid voltage data and the topological characteristics of the bidirectional DCAC conversion module, and the first bus voltage lower limit value can meet the minimum modulation ratio of the topology.

[0040] S102: If the charging and discharging device is in a discharging state, the second bus voltage lower limit value is calculated according to the actual voltage of the DC device; the larger value of the first bus voltage lower limit value and the second bus voltage lower limit value is used as the first bus voltage target value; and the voltage of the DC bus is loop-controlled based on the first bus voltage target value.

[0041] In this embodiment, the bus voltage of the DC bus, as the intermediate connection part of the bidirectional DCDC conversion module and the bidirectional DCAC conversion module, needs to meet the modulation ratio requirements of the two topologies at the same time. Therefore, after determining the actual voltage value of the DC device, it is necessary to convert the actual voltage value into the second bus voltage lower limit value on the DC bus side through the topological parameters of the bidirectional DCDC conversion circuit. The DC bus voltage in the charging state takes the larger value of the first bus voltage lower limit value calculated on the AC side and the second bus voltage lower limit value calculated on the DC side. Then, the voltage of the DC bus is loop-controlled using the obtained first bus voltage target value.

[0042] S103: If the charging and discharging device is in a charging state, the third bus voltage lower limit value is calculated based on the charging target value of the DC device, and the larger value between the first bus voltage lower limit value and the third bus voltage lower limit value is used as the second bus voltage target value; and the second bus voltage target value is sent to the AC side control module, so that the AC side control module performs loop control on the voltage of the DC bus according to the second bus voltage target value.

[0043] In this embodiment, after determining the charging target value of the DC device, it is necessary to convert the charging target value into the third bus voltage lower limit value on the DC bus side through the topological parameters of the bidirectional DCDC conversion circuit. The DC bus voltage in the discharge state takes the larger value of the first bus voltage lower limit value calculated on the AC side and the third bus voltage lower limit value calculated on the DC side. After calculating the second bus voltage target value, the DC side control module completes the control process in the charging state and sends the second bus voltage target value to the AC side control module. The AC side control module controls the operation of the bidirectional DCAC conversion module according to the second bus voltage target value.

[0044] It can be seen from the above embodiments that the bus voltage control method provided in this embodiment can realize real-time and intelligent control of the system bus voltage, and perform linear real-time control of the bus voltage according to different charging voltages (DC equipment voltages), different grid voltages and different load capacities, thereby achieving the purpose of achieving the highest system efficiency while ensuring the normal operation of the topology.

[0045] In one embodiment, Figure 2 The specific implementation process of S102 includes:

[0046] The larger value between the first bus voltage lower limit value and the second bus voltage lower limit value is used as the first bus voltage target minimum value.

[0047] The actual power of the power grid is obtained.

[0048] A first voltage margin is calculated based on the actual power of the power grid and the full load power of the charging and discharging device.

[0049] The first bus voltage target minimum value is added to the first voltage margin to obtain a first bus voltage target value.

[0050] In this embodiment, after calculating the first bus voltage target minimum value, the influence of the load rate on the bus voltage needs to be considered, and a certain margin needs to be left. Specifically, when the charging and discharging device is in the discharging state, the load is the power grid, so the load rate can be taken as the actual power of the power grid, and then based on the formula The first voltage margin is obtained, where ΔU3 represents the first voltage margin, P wIndicates the actual power of the grid, P m represents the full load power of the charging and discharging device, and k represents a preset adjustment coefficient, wherein the preset adjustment coefficient is obtained by actual calculation. For example, k can be 22.

[0051] In this embodiment, after the first bus voltage target value is calculated, in order to prevent the bus voltage from being too high, it is necessary to perform a limit processing on the first bus voltage target value.

[0052] In one embodiment, Figure 2 The specific implementation process of S103 includes:

[0053] The larger value between the first bus voltage lower limit value and the third bus voltage lower limit value is used as the second bus voltage target minimum value;

[0054] Obtaining actual power of the DC device;

[0055] Calculating a second voltage margin based on the actual power of the DC device and the full load power of the charging and discharging device;

[0056] The bus voltage target minimum value is added to the second voltage margin to obtain the second bus voltage target value.

[0057] In this embodiment, after calculating the second bus voltage target minimum value, the influence of the load rate on the bus voltage needs to be considered, and a certain margin needs to be left. Specifically, when the charging and discharging device is in the charging state, the load is a DC device, so the load rate can be taken as the actual power of the DC device, and then based on the formula The second voltage margin is obtained, where ΔU4 represents the second voltage margin, P z Indicates the actual power of the DC device, P m represents the full load power of the charging and discharging device, and k represents a preset adjustment coefficient, wherein the preset adjustment coefficient is obtained by actual calculation. For example, k can be 22.

[0058] In one embodiment, the bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; Figure 2 The specific implementation process of S102 also includes:

[0059] Adding the actual voltage of the DC device to the minimum boost value to obtain a first midpoint bus voltage;

[0060] The first midpoint bus voltage is converted into a second bus voltage lower limit value based on the topology parameters of the CLLC resonant conversion circuit.

[0061] In this embodiment, when the charging and discharging device is in the discharging state, that is, the DC device charges the grid, the DC side voltage is the actual voltage of the DC device. According to the characteristics of the bidirectional Buck-Boost circuit, the bus voltage needs to meet the minimum boost value of the topology. Therefore, the DC side control module needs to calculate the minimum value of the midpoint bus voltage according to the actual voltage of the DC device, that is, the first midpoint bus voltage U 21 =U dz +ΔU2. Among them, U 21 Indicates the first midpoint bus voltage, U dz It represents the actual voltage of the DC device, and ΔU2 represents the minimum boost value.

[0062] Specifically, the minimum boost value can be customized according to actual circuit requirements. For example, ΔU2 = 20V.

[0063] After calculating the first midpoint bus voltage, this embodiment also needs to multiply the first midpoint bus voltage by the topology parameter of the CLLC resonant conversion circuit to obtain the lower limit value of the second bus voltage corresponding to the DC bus. The topology parameter of the CLLC resonant conversion circuit can be 13 / 11.

[0064] In one embodiment, the bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; Figure 2 The specific implementation process of S102 also includes:

[0065] Based on the topology parameters of the CLLC resonant conversion circuit, converting the first bus voltage target value into a midpoint bus voltage target value;

[0066] The voltage of the midpoint bus is loop-controlled based on the midpoint bus voltage target value.

[0067] In this embodiment, since the CLLC resonant conversion circuit in this embodiment is open-loop controlled, the DC side voltage loop actually controls the voltage of the midpoint bus, and the circuit forms the corresponding bus voltage according to the transformer ratio.

[0068] In this embodiment, after obtaining the midpoint bus voltage target value, in order to prevent the bus voltage from being too high, the midpoint bus voltage target value needs to be limited. Exemplarily, the midpoint bus voltage target value can be limited to between 850V and 980V. Accordingly, the DC side control module uses the midpoint bus voltage target value after the limit processing as the given value of the midpoint bus to perform loop control on the bidirectional DCDC conversion circuit.

[0069] In one embodiment, the bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; Figure 2 The specific implementation process of S103 also includes:

[0070] Adding the charging target value of the DC device to the minimum boost value to obtain a second midpoint bus voltage;

[0071] The second midpoint bus voltage is converted into a third bus voltage lower limit value based on the topology parameters of the CLLC resonant conversion circuit.

[0072] Specifically, when the charging and discharging device is in the charging state, that is, the power grid charges the DC device, at this time, the DC side voltage is the charging target value of the DC device, and the charging target value can be a voltage value. According to the characteristics of the bidirectional Buck-Boost circuit, the bus voltage needs to meet the minimum boost value of the topology. Therefore, the DC side control module needs to calculate the minimum value of the midpoint bus voltage according to the charging target value of the DC device, that is, the second midpoint bus voltage U 22 =U dl +ΔU2. Among them, U 22 Indicates the second midpoint bus voltage, U dl It represents the charging target value of the DC device, and ΔU2 represents the minimum boost value.

[0073] After the second midpoint bus voltage is calculated, this embodiment also needs to multiply the second midpoint bus voltage by the topology parameter of the CLLC resonant conversion circuit to obtain a lower limit value of the third bus voltage corresponding to the DC bus.

[0074] In one embodiment, this embodiment provides an implementation process of a bus voltage control method for a charging and discharging device. The execution subject of the method is an AC side control module, and the process is described in detail as follows:

[0075] S201: Acquire voltage data of the power grid, where the voltage data of the power grid includes an effective value of a power grid line voltage and an instantaneous value of a power grid line voltage.

[0076] S202: Calculate a first bus voltage value based on the effective value of the grid line voltage and the topological parameters of the bidirectional DCAC conversion circuit.

[0077] Specifically, according to the bidirectional DCAC topology characteristics, the bus voltage requires a lower limit value to meet the minimum modulation ratio of the topology. Therefore, the AC side control module in this embodiment converts the real-time effective value of the grid voltage into the corresponding bus voltage lower limit value, that is, the first bus voltage value. The formula can be:

[0078]

[0079] S203: Selecting a larger value between the first bus voltage value and the grid line voltage instantaneous value as a first bus voltage lower limit value.

[0080] In this embodiment, the dynamic grid voltage fluctuation is considered. Since the instantaneous fluctuation time of the grid voltage is short, the effective value of the grid voltage cannot be calculated in time. Among them, U1 represents the lower limit of the first bus voltage, U n Indicates the effective value of the grid voltage, U s Indicates the instantaneous value of the grid voltage.

[0081] In one embodiment, after S203, the method provided in this embodiment further includes:

[0082] Adding the first bus voltage lower limit value to a preset modulation ratio margin to obtain a compensated first bus voltage lower limit value;

[0083] Accordingly, the specific implementation process of S204 includes:

[0084] The compensated first bus voltage lower limit value is sent to the DC side control module.

[0085] Specifically, in order to meet actual needs, the bidirectional DCAC conversion module needs to have a certain modulation ratio margin. The modulation ratio margin ΔU1 can be customized according to actual circuit requirements. For example, ΔU1 = 50V.

[0086] S204: Sending the first bus voltage lower limit value to a DC side control module, so that the DC side control module calculates a second bus voltage target value when the charging and discharging device is in a charging state according to the first bus voltage lower limit value.

[0087] S205: Acquire the second bus voltage target value sent by the DC side control module, and perform loop control on the voltage of the DC bus according to the second bus voltage target value.

[0088] In this embodiment, after obtaining the second bus voltage target value sent by the DC side control module, in order to avoid the bus voltage being too high, the AC side control module needs to limit the second bus voltage target value. Exemplarily, the limit range of the second bus voltage target value can be 720V-830V.

[0089] After obtaining the second bus voltage target value after the limiting process, the AC side control module uses the second bus voltage target value after the limiting process as the bus voltage set value of the DC bus to perform loop control on the bidirectional DCAC conversion circuit.

[0090] As another specific embodiment, when the bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit, another implementation method of the bus voltage control method of the charging and discharging device provided in this embodiment directly calculates the required data on the midpoint bus side through the DC side control module; its interaction process is described in detail as follows (wherein, the execution subject of SA1~SA5 is the DC side control module, and the execution subject of SB1~SB5 is the AC side control module):

[0091] SB1: Acquire voltage data of the power grid, wherein the voltage data of the power grid includes an effective value of a power grid line voltage and an instantaneous value of a power grid line voltage.

[0092] SB2: Calculate a first bus voltage value based on the effective value of the grid line voltage and the topological parameters of the bidirectional DCAC conversion circuit.

[0093] SB3: Select the larger value of the first bus voltage value and the instantaneous value of the grid line voltage as the first bus voltage lower limit value.

[0094] SB4: Send the first bus voltage lower limit value to the DC side control module.

[0095] SA1: Get the lower limit value of the first bus voltage sent by the AC side control module.

[0096] SA2: Based on the topological parameters of the CLLC resonant conversion circuit, the lower limit value of the first bus voltage is converted into a third midpoint bus voltage.

[0097] SA3: If the charging and discharging device is in a charging state, the second midpoint bus voltage is calculated based on the charging target value of the DC device; and the larger value of the second midpoint bus voltage and the third midpoint bus voltage is selected as the first midpoint bus voltage target value; based on the topological parameters of the CLLC resonant conversion circuit, the first midpoint bus voltage target value is converted into a second bus voltage target value, and the second bus voltage target value is sent to the AC side control module.

[0098] SA4: If the charging and discharging device is in a discharging state, the first midpoint bus voltage is calculated according to the actual voltage of the DC device; and the larger value of the first midpoint bus voltage and the third midpoint bus voltage is selected as the midpoint bus voltage target value; and the voltage of the midpoint bus is loop-controlled based on the midpoint bus voltage target value.

[0099] SB5: Acquire the second bus voltage target value sent by the DC side control module, and perform loop control on the voltage of the DC bus according to the second bus voltage target value.

[0100] This embodiment can not only meet the normal operation of the system topology within a wide voltage range, but also meet the system's real-time and intelligent control of the system bus voltage through the above process. According to different charging voltages (DC source voltages), different grid voltages, and different load capacities, the bus voltage is linearly controlled in real time, while ensuring the normal operation of the topology, the system achieves the highest efficiency and high-efficiency control requirements.

[0101] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean 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 embodiment of the present invention.

[0102] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0103] An embodiment of the present invention provides a bus voltage control device for a charging and discharging device, which is applied to a DC side control module, including:

[0104] A first bus voltage lower limit value acquisition module, used to acquire a first bus voltage lower limit value sent by an AC side control module, wherein the first bus voltage lower limit value is a voltage lower limit value corresponding to the DC bus, and the first bus voltage lower limit value is calculated based on voltage data of the power grid;

[0105] a first bus voltage control module, configured to calculate a second bus voltage lower limit value according to the actual voltage of the DC device if the charging and discharging device is in a discharging state; use the larger value of the first bus voltage lower limit value and the second bus voltage lower limit value as a first bus voltage target value; and perform loop control on the voltage of the DC bus based on the first bus voltage target value;

[0106] a second bus voltage control module, for calculating a third bus voltage lower limit value based on a charging target value of the DC device if the charging and discharging device is in a charging state, and taking a larger value between the first bus voltage lower limit value and the third bus voltage lower limit value as a second bus voltage target value; and sending the second bus voltage target value to the AC side control module, so that the AC side control module performs loop control on the voltage of the DC bus according to the second bus voltage target value.

[0107] In one embodiment, the first bus voltage control module includes:

[0108] The larger value between the first bus voltage lower limit value and the second bus voltage lower limit value is used as the first bus voltage target minimum value;

[0109] Obtaining actual power of the power grid;

[0110] Calculating a first voltage margin based on the actual power of the power grid and the full load power of the charging and discharging device;

[0111] The first bus voltage target minimum value is added to the first voltage margin to obtain a first bus voltage target value.

[0112] In one embodiment, the second bus voltage control module includes:

[0113] The larger value between the first bus voltage lower limit value and the third bus voltage lower limit value is used as the second bus voltage target minimum value;

[0114] Obtaining actual power of the DC device;

[0115] Calculating a second voltage margin based on the actual power of the DC device and the full load power of the charging and discharging device;

[0116] The bus voltage target minimum value is added to the second voltage margin to obtain the second bus voltage target value.

[0117] In one embodiment, the bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; the first bus voltage control module also includes:

[0118] Adding the actual voltage of the DC device to the minimum boost value to obtain a first midpoint bus voltage;

[0119] The first midpoint bus voltage is converted into a second bus voltage lower limit value based on the topology parameters of the CLLC resonant conversion circuit.

[0120] In one embodiment, the bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; the second bus voltage control module also includes:

[0121] Adding the charging target value of the DC device to the minimum boost value to obtain a second midpoint bus voltage;

[0122] The second midpoint bus voltage is converted into a third bus voltage lower limit value based on the topology parameters of the CLLC resonant conversion circuit.

[0123] In one embodiment, the bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; the first bus voltage control module includes:

[0124] Based on the topology parameters of the CLLC resonant conversion circuit, converting the first bus voltage target value into a midpoint bus voltage target value;

[0125] The voltage of the midpoint bus is loop-controlled based on the midpoint bus voltage target value.

[0126] The embodiment of the present invention further discloses a structure of a bus voltage control device for a charging and discharging device, which is applied to an AC side control module and includes:

[0127] A voltage data acquisition module, used to acquire the voltage data of the power grid, wherein the voltage data of the power grid includes an effective value of a power grid line voltage and an instantaneous value of a power grid line voltage;

[0128] A first bus voltage calculation module, used for calculating a first bus voltage value based on the effective value of the grid line voltage and the topological parameters of the bidirectional DCAC conversion circuit;

[0129] A first bus voltage lower limit value calculation module, used for selecting the larger value between the first bus voltage value and the grid line voltage instantaneous value as the first bus voltage lower limit value;

[0130] A first bus voltage lower limit value sending module, used for sending the first bus voltage lower limit value to a DC side control module, so that the DC side control module calculates a second bus voltage target value when the charging and discharging device is in a charging state according to the first bus voltage lower limit value;

[0131] The third bus voltage control module is used to obtain the second bus voltage target value sent by the DC side control module, and perform loop control on the voltage of the DC bus according to the second bus voltage target value.

[0132] It can be seen from the above embodiments that the bus voltage control method provided in this embodiment can realize real-time and intelligent control of the system bus voltage, and perform linear real-time control of the bus voltage according to different charging voltages (DC equipment voltages), different grid voltages and different load capacities, thereby achieving the purpose of achieving the highest system efficiency while ensuring the normal operation of the topology.

[0133] Figure 4 FIG. 1 is a schematic diagram of an AC side control module / DC side control module provided by an embodiment of the present invention. Figure 4 As shown, the AC side control module / DC side control module 4 of this embodiment includes: a processor 40, a memory 41, and a computer program 42 stored in the memory 41 and executable on the processor 40. When the processor 40 executes the computer program 42, the steps in the above-mentioned bus voltage control method embodiments of each charging and discharging device are implemented. For example, when it is a DC side control module, Figure 2 Steps 101 to 103 are shown.

[0134] Exemplarily, the computer program 42 may be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, which are used to describe the execution process of the computer program 42 in the AC side control module / DC side control module 4.

[0135] The AC side control module / DC side control module 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will appreciate that Figure 4 It is only an example of the AC side control module / DC side control module 4 and does not constitute a limitation of the AC side control module / DC side control module 4. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the terminal may also include input and output devices, network access devices, buses, etc.

[0136] The processor 40 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) 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, etc.

[0137] The memory 41 may be an internal storage unit of the AC side control module / DC side control module 4, such as a hard disk or memory of the AC side control module / DC side control module 4. The memory 41 may also be an external storage device of the AC side control module / DC side control module 4, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the AC side control module / DC side control module 4. Further, the memory 41 may also include both the internal storage unit of the AC side control module / DC side control module 4 and an external storage device. The memory 41 is used to store the computer program and other programs and data required by the terminal. The memory 41 may also be used to temporarily store data that has been output or is to be output.

[0138] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by 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 embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0139] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0140] Those skilled in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0141] In the embodiments provided by the present 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 only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0142] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0143] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0144] If the integrated module / unit is implemented in the form of 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, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the bus voltage control method embodiment of each charging and discharging device can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practices in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practices, computer-readable media does not include electrical carrier signals and telecommunication signals.

[0145] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A bus voltage control method for a charging and discharging device, characterized in that: The charging and discharging device comprises a bidirectional DCDC conversion module and a bidirectional DCAC conversion module, wherein the first DC side of the bidirectional DCDC conversion module is used to connect a DC device; the second DC side of the bidirectional DCDC conversion module is connected to the DC side of the bidirectional DCAC conversion module through a DC bus, and the AC side of the bidirectional DCAC conversion module is used to connect to a power grid; The method is applied to a DC side control module, comprising: Obtaining a first bus voltage lower limit value sent by an AC side control module, where the first bus voltage lower limit value is a voltage lower limit value corresponding to the DC bus, and the first bus voltage lower limit value is calculated based on voltage data of the power grid; If the charging and discharging device is in a discharging state, the second bus voltage lower limit value is calculated according to the actual voltage of the DC device; the larger value of the first bus voltage lower limit value and the second bus voltage lower limit value is used as the first bus voltage target value; and the voltage of the DC bus is loop-controlled based on the first bus voltage target value; If the charging and discharging device is in a charging state, the third bus voltage lower limit value is calculated based on the charging target value of the DC device, and the larger value of the first bus voltage lower limit value and the third bus voltage lower limit value is used as the second bus voltage target value; and the second bus voltage target value is sent to the AC side control module, so that the AC side control module performs loop control on the voltage of the DC bus according to the second bus voltage target value.

2. The bus voltage control method of the charging and discharging device according to claim 1, characterized in that: The taking the larger value of the first bus voltage lower limit value and the second bus voltage lower limit value as the first bus voltage target value comprises: The larger value between the first bus voltage lower limit value and the second bus voltage lower limit value is used as the first bus voltage target minimum value; Obtaining actual power of the power grid; Calculating a first voltage margin based on the actual power of the power grid and the full load power of the charging and discharging device; The first bus voltage target minimum value is added to the first voltage margin to obtain a first bus voltage target value.

3. The bus voltage control method of the charging and discharging device according to claim 1, characterized in that: The taking the larger value of the first bus voltage lower limit value and the third bus voltage lower limit value as the second bus voltage target value comprises: The larger value between the first bus voltage lower limit value and the third bus voltage lower limit value is used as the second bus voltage target minimum value; Obtaining actual power of the DC device; Calculating a second voltage margin based on the actual power of the DC device and the full load power of the charging and discharging device; The bus voltage target minimum value is added to the second voltage margin to obtain the second bus voltage target value.

4. The bus voltage control method of the charging and discharging device according to claim 1, characterized in that: The bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; The calculating the lower limit value of the second bus voltage according to the actual voltage of the DC device includes: Adding the actual voltage of the DC device to the minimum boost value to obtain a first midpoint bus voltage; The first midpoint bus voltage is converted into a second bus voltage lower limit value based on the topology parameters of the CLLC resonant conversion circuit.

5. The bus voltage control method of the charging and discharging device according to claim 1, characterized in that: The bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; The calculating the lower limit value of the third bus voltage based on the charging target value of the DC device includes: Adding the charging target value of the DC device to the minimum boost value to obtain a second midpoint bus voltage; The second midpoint bus voltage is converted into a third bus voltage lower limit value based on the topology parameters of the CLLC resonant conversion circuit.

6. The bus voltage control method of the charging and discharging device according to claim 1, characterized in that: The bidirectional DCDC conversion module includes a bidirectional BUCK-BOOST circuit and a CLLC resonant conversion circuit; and the bidirectional BUCK-BOOST circuit is connected to the CLLC resonant conversion circuit through a midpoint bus, and the CLLC resonant conversion circuit is connected to the bidirectional DCAC conversion module through a DC bus; The loop controlling the voltage of the DC bus based on the first bus voltage target value includes: Based on the topology parameters of the CLLC resonant conversion circuit, converting the first bus voltage target value into a midpoint bus voltage target value; The voltage of the midpoint bus is loop-controlled based on the midpoint bus voltage target value.

7. A bus voltage control method for a charging and discharging device, characterized in that: The charging and discharging device comprises a bidirectional DCDC conversion module and a bidirectional DCAC conversion module, wherein the first DC side of the bidirectional DCDC conversion module is used to connect a DC device; the second DC side of the bidirectional DCDC conversion module is connected to the DC side of the bidirectional DCAC conversion module through a DC bus, and the AC side of the bidirectional DCAC conversion module is used to connect to a power grid; The method is applied to an AC side control module, comprising: Acquiring voltage data of the power grid, wherein the voltage data of the power grid includes an effective value of a power grid line voltage and an instantaneous value of a power grid line voltage; Calculating a first bus voltage value based on the grid line voltage effective value and the topological parameters of the bidirectional DCAC conversion circuit; Selecting the larger value of the first bus voltage value and the instantaneous value of the grid line voltage as the first bus voltage lower limit value; Sending the first bus voltage lower limit value to a DC side control module, so that the DC side control module calculates a second bus voltage target value when the charging and discharging device is in a charging state according to the first bus voltage lower limit value; The second bus voltage target value sent by the DC side control module is obtained, and the voltage of the DC bus is loop-controlled according to the second bus voltage target value.

8. A DC side control module, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. An AC side control module, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to claim 7 are implemented.

10. A charging and discharging system, characterized in that: comprising a charging and discharging device, a DC side control module according to any one of claims 1 to 6, and an AC side control module according to claim 7; The charging and discharging device comprises a bidirectional DCDC conversion module and a bidirectional DCAC conversion module, wherein the first DC side of the bidirectional DCDC conversion module is used to connect a DC device; the second DC side of the bidirectional DCDC conversion module is connected to the DC side of the bidirectional DCAC conversion module through a DC bus, and the AC side of the bidirectional DCAC conversion module is used to connect to a power grid; The DC side control module is used to control the operation of the bidirectional DCDC conversion module; The AC side control module is used to control the operation of the bidirectional DCAC conversion module.

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