Inverter, energy storage system and control method of inverter

Abstract

The invention relates to the technical field of energy, and provides an inverter, an energy storage system and a control method of the inverter. An inverter is connected between an alternating current source and an energy storage device cluster, and the energy storage device cluster comprises at least X energy storage devices connected in series. The inverter comprises an AC-DC conversion unit and a control unit. Since the control unit can acquire the voltage value of each energy storage device through the second power branch, the voltage difference between the energy storage devices can be determined based on the voltage value of each energy storage device, and then the target energy storage device to be charged can be determined from the energy storage device cluster. And the first electric power branch or the second electric power branch is conducted to serve as an electricity supplementing path to supplement electricity for the target energy storage equipment, so that the voltage difference between the energy storage equipment in the energy storage equipment cluster can be reduced, and voltage balance between different energy storage equipment in the energy storage equipment cluster is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy, and particularly relates to an inverter, an energy storage system, and a control method of the inverter. BACKGROUND

[0002] With the rapid development of new energy technology, more and more green power generation equipment is popularized and promoted. For example, solar power generation equipment, wind power generation equipment, etc. are installed on the roof of a user to generate power, and then the energy storage equipment is used to store the generated power, which can not only be used by the user at any time, but also can supply power to the power grid. In this way, the demand for users to configure energy storage systems also increases. At present, the energy storage system includes an energy storage device cluster having a plurality of energy storage devices. Due to the inconsistency between the electric cores in the energy storage devices, the pressure difference between the electric cores is likely to be large in long-term use. In order to achieve the balance between the electric cores, a balancing circuit, such as an active balancing circuit or a passive balancing circuit, can be configured in the energy storage device to achieve the balance between the electric cores.

[0003] However, in actual use, there is also a certain pressure difference between different energy storage devices. Only the balance between the electric cores cannot fundamentally eliminate the pressure difference between different energy storage devices in the energy storage device cluster, which still affects the normal charging and discharging work of the entire energy storage device cluster. SUMMARY

[0004] The purpose of the present application is to provide an inverter, an energy storage system, and a control method of the inverter, aiming to provide a new inverter scheme, which can realize the voltage balance between different energy storage devices in the energy storage device cluster.

[0005] The first aspect of the embodiment of the present application provides an inverter connected between an alternating current source and an energy storage device cluster. The energy storage device cluster includes at least X series of energy storage devices, X is an integer, and X≥2. The inverter includes:

[0006] An AC-DC conversion unit is configured with an AC side connection end and a DC side connection end. The AC side connection end is used to connect the AC source, and the DC side connection end is used to connect the first power branch;

[0007] A control unit is connected with each energy storage device through a second power branch;

[0008] The control unit is used to obtain the voltage value of each energy storage device through the second power branch, determine the target energy storage device to be compensated from the energy storage device cluster based on the voltage value of each energy storage device, and turn on the compensation path to compensate the target energy storage device. The compensation path includes the first power branch or the second power branch.

[0009] A second aspect of this application provides an energy storage system, including the inverter provided in the first aspect above, and X energy storage devices.

[0010] A third aspect of this application provides a control method for an inverter, applied to the inverter described in the first aspect, the control method comprising:

[0011] The voltage value of each energy storage device is obtained through the second power branch;

[0012] The target energy storage device to be recharged is determined from the energy storage device cluster based on the voltage value of each energy storage device;

[0013] The power supply path is connected to provide power to the target energy storage device; the power supply path includes a first power branch or a second power branch.

[0014] A fourth aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the electronic device, wherein the processor executes the computer program to implement the steps of the control method for the inverter provided in the third aspect above.

[0015] The fifth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the inverter control method provided in the third aspect above.

[0016] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0017] The inverter described above is connected between an AC source and an energy storage device cluster, which includes at least X energy storage devices connected in series. The inverter includes an AC-DC conversion unit and a control unit. The AC-DC conversion unit is configured with an AC-side connection terminal and a DC-side connection terminal. The AC-side connection terminal is used to connect to the AC source, and the DC-side connection terminal is used to connect to a first power branch. The control unit is connected to each energy storage device through a second power branch. Since the control unit can obtain the voltage value of each energy storage device through the second power branch, it can determine the voltage difference between the energy storage devices based on the voltage value of each device. This allows it to identify the target energy storage device to be recharged from the energy storage device cluster, and then connect either the first or second power branch as a recharge path to recharge the target energy storage device. This reduces the voltage difference between the energy storage devices in the cluster, achieving voltage balance among the different energy storage devices. Therefore, it avoids the voltage difference between different energy storage devices affecting the normal charging and discharging operation of the entire energy storage device cluster, improving the stability, endurance, and service life of the energy storage device cluster.

[0018] Furthermore, after identifying the target energy storage device to be recharged from the energy storage device cluster, either the first power branch or the second power branch can be activated as a recharge path to power the target energy storage device. This means at least two types of power branches can be provided for recharging the target energy storage device, or at least two recharge schemes can be offered. Since the control unit can obtain the voltage value of each energy storage device through the second power branch (i.e., this second power branch serves as a sampling branch for the energy storage device), the recharge requirements of the target energy storage device under different voltage differential conditions can be met. This, in turn, can minimize the voltage differential between the energy storage devices in the cluster and improve the accuracy of voltage equalization among different energy storage devices within the cluster. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an inverter provided in an embodiment of this application;

[0020] Figure 2 This is a schematic diagram of the specific structure of an inverter provided in an embodiment of this application;

[0021] Figure 3 A schematic diagram of the specific structure of an inverter provided in another embodiment of this application;

[0022] Figure 4 A schematic diagram of the specific structure of an inverter provided in another embodiment of this application;

[0023] Figure 5 A schematic diagram of the specific structure of an inverter provided in another embodiment of this application;

[0024] Figure 6 A flowchart illustrating the implementation of an inverter control method provided in this application embodiment;

[0025] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0027] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0028] For example, due to the inconsistencies between the cells in an energy storage device, a large voltage difference between the cells may easily occur during long-term use. In order to achieve balance between the cells, a balancing circuit, such as an active balancing circuit or a passive balancing circuit, can be configured in the energy storage device to achieve balance between the cells.

[0029] However, in actual use, there is a certain pressure difference between different energy storage devices. Simply achieving balance between cells cannot fundamentally eliminate the pressure difference between different energy storage devices in the energy storage device cluster, and will still affect the normal charging and discharging operation of the entire energy storage device cluster.

[0030] To address the aforementioned technical problems, this embodiment provides an inverter connected between an AC source and an energy storage device cluster, which includes at least X energy storage devices connected in series. The inverter includes an AC-DC conversion unit and a control unit. The AC-DC conversion unit is configured with an AC-side connection terminal and a DC-side connection terminal. The AC-side connection terminal is used to connect to the AC source, and the DC-side connection terminal is used to connect to a first power branch. The control unit is connected to each energy storage device through a second power branch. Since the control unit can obtain the voltage value of each energy storage device through the second power branch, it can determine the voltage difference between the energy storage devices based on the voltage value of each device. This allows it to identify the target energy storage device to be recharged from the energy storage device cluster, and then connect either the first or second power branch as a recharge path to recharge the target energy storage device. This reduces the voltage difference between the energy storage devices in the cluster and achieves voltage balance among the different energy storage devices. This avoids the voltage difference between different energy storage devices in the energy storage cluster from affecting the normal charging and discharging operation of the entire energy storage cluster, thereby improving the stability, endurance and service life of the energy storage cluster.

[0031] Furthermore, after identifying the target energy storage device to be recharged from the energy storage device cluster, either the first power branch or the second power branch can be activated as a recharge path to power the target energy storage device. This means at least two types of power branches can be provided for recharging the target energy storage device, or at least two recharge schemes can be offered. Since the control unit can obtain the voltage value of each energy storage device through the second power branch (i.e., this second power branch serves as a sampling branch for the energy storage device), the recharge requirements of the target energy storage device under different voltage differential conditions can be met. This, in turn, can minimize the voltage differential between the energy storage devices in the cluster and improve the accuracy of voltage equalization among different energy storage devices within the cluster.

[0032] This embodiment provides an inverter that can be configured in energy storage device clusters. Unlike energy storage devices that achieve voltage equalization between cells through their built-in equalization circuits, the inverter provided in this embodiment uses an AC source as its power source to replenish the target energy storage device in the energy storage device cluster. In the process of achieving voltage parity between the target energy storage device and the energy storage device with the highest voltage, no energy is discharged from the target energy storage device due to equalization requirements. This not only avoids energy waste but also improves the overall endurance of the energy storage device cluster.

[0033] The following provides a detailed description of an inverter provided in this embodiment through specific implementation methods.

[0034] Figure 1 A schematic diagram of the structure of an inverter provided in an embodiment of this application is shown. Figure 1 As shown, the inverter 100 is connected between the AC source 110 and the energy storage device cluster 120, which includes at least X energy storage devices 121 connected in series, where X is an integer and X≥2. Figure 1 In this inverter 100, there are AC / DC conversion unit 10 and control unit 20. Specifically:

[0035] The AC / DC conversion unit 10 is configured with an AC-side connection terminal and a DC-side connection terminal. The AC-side connection terminal is used to connect to an AC source 110, and the DC-side connection terminal is used to connect to the first power branch 30. The control unit 20 is connected to each energy storage device 121 through a second power branch 40. The control unit 20 is used to obtain the voltage value of each energy storage device 121 through the second power branch 40, determine the target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, and conduct a recharge path to recharge the target energy storage device. The recharge path includes either the first power branch 30 or the second power branch 40.

[0036] In this embodiment, the AC / DC conversion unit 10 can be used to realize the exchange of electrical energy between the AC source 110 and the energy storage device cluster 120. Specifically, the AC / DC conversion unit 10 can be a bidirectional AC-DC conversion circuit with bidirectional conversion capability. For example, the bidirectional AC-DC conversion circuit in the AC / DC conversion unit 10 can convert the AC power provided by the AC source 110 into DC power, and use this DC power to charge the energy storage device cluster 120. As another example, the bidirectional AC-DC conversion circuit in the AC / DC conversion unit 10 can convert the electrical energy provided by the energy storage device cluster 120 into AC power and output it to the AC source 110.

[0037] In practical applications, the energy storage device 121 mentioned in this embodiment can specifically be an existing battery pack, battery, or cell cluster. Since the energy storage device cluster 120 includes X energy storage devices 121 connected in series, when the inverter 100 converts the electrical energy from the AC source 110 into DC power to charge the energy storage device cluster 120, the charging voltage output by the inverter 100 needs to be greater than the sum of the voltages of the X energy storage devices 121. That is, when using the inverter 100 to charge the energy storage device cluster 120, the more energy storage devices 121 in the cluster, the higher the charging voltage output by the inverter 100.

[0038] For example, taking an energy storage device 121 comprising four series-connected cell clusters, each cell cluster consisting of 13 cells, each cell being 3.5V, when charging a single energy storage device 121, its charging voltage must be at least greater than 3.5 * 13 * 4 = 182V. If an energy storage device cluster 120 includes X energy storage devices 121, taking X = 8 as an example, when using an inverter 100 to charge the energy storage device cluster 120, the charging voltage must be at least equal to or greater than 182 * 8 = 1456V.

[0039] It should be noted that when the inverter 100 is used to charge the energy storage device cluster 120, it is actually charging X energy storage devices 121 connected in series. At this time, the AC power provided by the AC source 110 can be converted by the AC-DC conversion unit 10 to obtain DC power that is compatible with the energy storage device cluster 120. Then, the DC power is used to charge the energy storage device cluster 120 through the charging and discharging circuit.

[0040] For example, as one possible implementation, the AC / DC conversion unit 10 can be implemented using a unidirectional AC-DC conversion circuit. Here, the unidirectional AC-DC conversion circuit can specifically include a rectifier circuit, which rectifies the AC power provided by the AC source 110 and outputs it to the charging / discharging circuit to charge the energy storage device cluster 120. Here, the charging / discharging circuit refers to a circuit that can be used to charge the energy storage device cluster 120 and also to obtain electrical energy from the energy storage device cluster 120 and transfer it to the AC source 110. This charging / discharging circuit is different from the first power branch 30 and also different from the second power branch 40. In a specific implementation, the charging / discharging circuit can be considered as the main energy transfer circuit between the energy storage device cluster 120 and the inverter 100. Figure 1 As shown, the inverter 100 can form a charging and discharging circuit with the energy storage device cluster 120 through the transmission ports (P+, P-). Here, the transmission ports (P+, P-) can also be understood as nodes of the DC bus (not shown in the figure) in the inverter 100.

[0041] In this embodiment, the first power branch 30 differs from the charging / discharging circuit in that it is used to replenish the voltage of the energy storage device 121 (i.e., the target energy storage device) when there is a large voltage difference between some energy storage devices 121 in the energy storage device cluster 120 and the energy storage device with the highest voltage. That is, each energy storage device 121 in the energy storage device cluster 120 can be connected in parallel to the first power branch 30. Therefore, when replenishing the target energy storage device through the first power branch 30 as a replenishment path, the voltage supplied to the first power branch 30 is necessarily lower than the voltage of the charging / discharging circuit.

[0042] In conjunction with the above examples, in some examples, the AC / DC conversion unit 10 may also include a DC-DC conversion circuit. The rectifier circuit rectifies the AC power supplied by the AC source 110 to output initial DC power. The DC-DC conversion circuit then performs voltage conversion on this DC power, for example, converting the initial DC power into a high-frequency square wave voltage or current, and then smoothing it through rectification to output a lower voltage DC power. Specifically, the lower voltage DC power can be DC power with a voltage greater than or equal to 42V, for example, DC power with a voltage between 50V and 55V.

[0043] It is easy to understand that, in specific implementations, the AC source 110 can be mains power, an uninterruptible power supply, etc. Here, considering that when the inverter 100 charges the energy storage device cluster 120, the charging status of each energy storage device 121 in the cluster 120 is different, leading to a gradual increase in the voltage difference between the energy storage devices 121. To achieve charging balance within the energy storage device cluster 120, the control unit 20 in the inverter 100 obtains the voltage value of each energy storage device 121 through the second power branch 40. Here, the second power branch 40 can be understood as a communication branch between the control unit 20 and each energy storage device 121. It is understood that each energy storage device 121 is equipped with a battery management system, which can obtain the voltage value of each cell in the energy storage device 121 and calculate the voltage value of the energy storage device 121 itself.

[0044] As one possible implementation, in practice, the control unit 20 connects to the battery management system in the energy storage device 121 via the second power branch 40, thereby obtaining the voltage value of each energy storage device 121. Here, the second power branch 40 can also refer to the branch connecting the inverter 100 and the sampling branch of the energy storage device 121.

[0045] In all embodiments of this application, the control unit 20 determines the target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121. The target energy storage device generally refers to the energy storage device in the energy storage device cluster 120 with a lower voltage value and a larger voltage difference compared to the energy storage device with the highest voltage. Specifically, when the control unit 20 determines the target energy storage device from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, it can be done by comparing the voltage differences between each energy storage device 121.

[0046] For example, by comparing the voltage values ​​of each energy storage device, the energy storage device with the lowest voltage value can be selected as the target energy storage device.

[0047] For example, by calculating the voltage difference between the various energy storage devices, the energy storage device with the lower voltage among the two energy storage devices with the largest voltage difference is selected as the target energy storage device. It can be understood that the two energy storage devices with the largest voltage difference here must be the target energy storage device with the lowest voltage and the energy storage device with the highest voltage in the energy storage device cluster 120.

[0048] After the control unit 20 determines the target energy storage device from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, it can replenish power to the target energy storage device by connecting a power replenishment path. Here, the power replenishment path includes a first power branch 30 or a second power branch 40. Since the first power branch 30 is the branch connected to the DC side of the AC / DC conversion unit 10, and the second power branch 40 can be understood as the communication branch between the control unit 20 and each energy storage device 121, the replenishment voltage / power when using the first power branch 30 as the power replenishment path to replenish power to the target energy storage device is greater than the replenishment voltage / power when using the second power branch 40 as the power replenishment path to replenish power to the target energy storage device.

[0049] As one embodiment, the AC / DC conversion unit 10 is used to output a first supplementary power to the first power branch 30 using the AC power provided by the AC source 110. Correspondingly, the control unit 20 is also used to output a second supplementary power to the second power branch 40.

[0050] In this embodiment, the voltage of the first replenishing energy is greater than the voltage of the second replenishing energy.

[0051] It should be noted that when using the first power branch 30 as a charging path to charge the target energy storage device, the charging is applied to the entire target energy storage device in the energy storage device cluster 120. That is, when using the first power branch 30 as a charging path to charge the target energy storage device, one or more target energy storage devices in the energy storage device cluster 120 can be charged simultaneously. When using the second power branch 40 as a charging path to charge the target energy storage device, if there are multiple target energy storage devices, they can be charged through the second power branch 40 connected to each target energy storage device. It is worth noting that since the second power branch 40 is used to connect the control unit 20 and the battery management system of the energy storage device 121, for a single target energy storage device, when the control unit 20 activates the second power branch as a charging path to charge the target energy storage device, the second charging power output by the control unit 20 to the second power branch 40 can charge any one cell in the target energy storage device through the battery management system and cell circuit.

[0052] As an example, the control unit 20 is also used to instruct the energy storage device cluster 120 to disconnect the series path between each energy storage device 121 before the power supply path is connected to supply power to the target energy storage device.

[0053] As one possible implementation, the control unit 20 can interact with each energy storage device 121 in the energy storage device cluster 120 via the second power branch 40. For example, the control unit 20 can interact with the battery management system of each energy storage device 121 via the second power branch 40. Based on this, the control unit 20 can send control commands to each energy storage device 121 via the second power branch 40, instructing the battery management systems of all energy storage devices 121 to disconnect the charge / discharge switches, thereby instructing the energy storage device cluster 120 to disconnect the series connection between the energy storage devices 121.

[0054] As another possible implementation, when all energy storage devices 121 in the energy storage device cluster 120 are connected in series, the energy management system in the energy storage device cluster 120 can be selected. That is, the battery management system of the energy storage device 121 with the highest voltage in the energy storage device cluster 120 can be used as the energy management system. The control unit 20 can interact with the battery management system (energy management system) of the energy storage device 121 with the highest voltage through the second power branch 40. Based on this, the control unit 20 can send control commands to the battery management system (energy management system) of the energy storage device 121 with the highest voltage through the second power branch 40, instructing the battery management system (energy management system) of the energy storage device 121 with the highest voltage to instruct the battery management systems of all energy storage devices 121 to disconnect the charge and discharge switches, thereby instructing the energy storage device cluster 120 to disconnect the series path between the energy storage devices 121.

[0055] It is easy to understand that, in practical implementation, the control unit 20 can decide whether to activate the first power branch 30 or the second power branch 40 to replenish power to the target energy storage device based on the voltage difference between the target energy storage device and the energy storage device with the highest voltage. It is worth noting that for a single target energy storage device, only one power branch is activated for replenishment; that is, when activating the connection between the target energy storage device and the first power branch 30, the connection between the target energy storage device and the second power branch 40 will not be activated. Similarly, when activating the connection between the target energy storage device and the second power branch 40, the connection between the target energy storage device and the first power branch 30 will not be activated.

[0056] The above scheme utilizes the control unit 20 in the inverter 100 to obtain the voltage value of each energy storage device 121 through the second power branch, thereby identifying the target energy storage device to be recharged from the energy storage device cluster 120. By using the control unit 20 to connect the first power branch 30 or the second power branch 40 as a recharge path to recharge the target energy storage device, the voltage difference between the energy storage devices 121 in the energy storage device cluster 120 can be reduced, achieving voltage balance among different energy storage devices in the energy storage device cluster 120. This avoids the voltage difference between different energy storage devices in the energy storage device cluster 120 affecting the normal charging and discharging operation of the entire energy storage device cluster 120, thus improving the stability, endurance, and service life of the energy storage device cluster 120.

[0057] Figure 2 A schematic diagram of the specific structure of an inverter provided in an embodiment of this application is shown. As an embodiment, the AC / DC conversion unit 10 includes an AC / DC conversion circuit 11, which is configured with a positive connection terminal 11+ and a negative connection terminal 11-.

[0058] like Figure 2 As shown, in this embodiment, the first power branch 30 includes a positive power line 31 and a negative power line 32. The positive power line 31 is used to connect the positive connection terminal 11+ to the positive terminal B+ of each energy storage device 121, and the negative power line 32 is used to connect the negative connection terminal 11- to the negative terminal B- of each energy storage device 121.

[0059] For example, when the control unit 20 determines the target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, it can choose to activate the first power branch 30 or the second power branch 40 to recharge the target energy storage device.

[0060] For example, when the voltage difference between the target energy storage device and the energy storage device with the highest voltage in the energy storage device cluster 120 is greater than 1V to 1.2V, the first power branch 30 can be turned on to supplement the target energy storage device.

[0061] For example, when the voltage difference between the target energy storage device and the energy storage device with the highest voltage in the energy storage device cluster 120 is less than 1V to 1.2V, the second power branch 40 can be turned on to supplement the target energy storage device.

[0062] As one possible implementation method, when the control unit 20 connects the first power branch 30 to replenish the target energy storage device, the control unit 20 can specifically control the AC-DC conversion circuit 11 to work, and / or control the AC-DC conversion circuit 11 to connect its connection with the positive power line 31 and the negative power line 32, thereby enabling the AC-DC conversion circuit 11 to use the AC power provided by the AC source 110 to perform AC-DC conversion, output the first replenishment power to the first power branch 30, and use the first replenishment power to replenish the target energy storage device.

[0063] As another possible implementation, a first switching unit for connecting the energy storage device 121 is provided in the first power branch 30, and / or a second switching unit connected to the first power branch 30 is provided in the energy storage device 121. When the control unit 20 turns on the first power branch 30 to replenish power to the target energy storage device, it can specifically turn on the first switching unit and / or the second switching unit, so that the target energy storage device is connected to the first power branch 30, thereby enabling the AC / DC conversion circuit 11 to perform AC / DC conversion using the AC power provided by the AC source 110, outputting first replenishing power to the first power branch 30, and using this first replenishing power to replenish power to the target energy storage device.

[0064] It is easy to understand that since the control unit 20 obtains the voltage value of each energy storage device 121 through the second power branch 40, meaning that the second power branch 40 is physically conductive, when the control unit 20 activates the second power branch 40 to replenish power to the target energy storage device, it can be understood that it outputs a replenishing voltage to the target energy storage device through the second power branch 40. In specific implementation, when the control unit 20 activates the second power branch 40 to replenish power to the target energy storage device, it can specifically output a replenishing voltage to the target energy storage device through the second power branch 40.

[0065] Figure 3 A schematic diagram of the specific structure of an inverter according to another embodiment of this application is shown. As an embodiment, it is related to... Figure 2 The difference in the illustrated embodiment is that, Figure 3 In the illustrated embodiment, the first power branch 30 further includes a first switch pair 33 for connecting the energy storage device 121. Specifically, the control unit 20 is configured to determine, based on the voltage value of each energy storage device 121, a first target energy storage device to be recharged from the energy storage device cluster 120, control the first switch pair 33 connected to the first target energy storage device to be turned on, and use the first rechargeable energy to recharge the first target energy storage device. Wherein, the first voltage difference between the first target energy storage device and the energy storage device with the highest voltage is equal to or greater than a first threshold.

[0066] In this embodiment, any one of the energy storage devices 121 in the energy storage device cluster 120 can be connected to the first power branch 30 via the first switch pair 33. The first threshold refers to the voltage difference value condition that triggers the use of the first supplementary power to replenish the first target energy storage device, and is also the condition for determining the first target energy storage device. That is, when the voltage difference between any two energy storage devices 121 in the energy storage device cluster 120 is equal to or greater than the first threshold, the first target energy storage device can be determined, and the use of the first supplementary power to replenish the first target energy storage device can be triggered.

[0067] Combination Figures 1 to 3 It is easy to understand that in the energy storage device cluster 120, among the X energy storage devices 121 connected in series, the positive terminal of the first energy storage device is connected to the positive terminal P+ of the inverter 100, and the negative terminal of the last energy storage device is connected to the negative terminal P- of the inverter 100. The positive terminal B+ and the negative terminal B- of each energy storage device 121 in the energy storage device cluster 120 can be connected to the first power branch 30 through the first switch pair 33. In a specific implementation, the energy storage device 121 can be configured with two interfaces, one for connecting the energy storage devices in series and the other for connecting to the first switch pair 33 in the inverter 100. Of course, in a specific implementation, different connecting wires or ports can also be led out through one interface to achieve the connection between the energy storage devices in series and the connection to the first switch pair 33 in the inverter 100; this is not limited here.

[0068] like Figure 3 As shown, the first switch pair 33 includes a first switch S1 and a second switch S2. In a specific implementation, the first switch pair 33 is controlled by the control unit 20. That is, when the control unit 20 determines the first target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, it can send a control signal to the first switch pair 33 connected to the first target energy storage device to control the first switch pair 33 to close, thereby opening the path between the first target energy storage device and the first power branch 30, and using the first rechargeable energy to recharge the first target energy storage device.

[0069] As one possible implementation, X energy storage devices 121 connected in series in the energy storage device cluster 120 are correspondingly connected to X sets of first switch pairs 33. In a specific implementation, the identification correspondence between the energy storage devices 121 and the first switch pairs 33 can be pre-configured in the control unit 20. Based on this, when the control unit 20 determines the first target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, it can determine the first switch pair 33 connected to the first target energy storage device according to the identification correspondence, and then send a control signal to the first switch pair 33 connected to the first target energy storage device to control the first switch pair 33 to close, thereby opening the path between the first target energy storage device and the first power branch 30, and using the first rechargeable energy to recharge the first target energy storage device.

[0070] Figure 4 A schematic diagram of the specific structure of an inverter according to another embodiment of this application is shown. As an embodiment, it is related to... Figure 2 The difference in the illustrated embodiment is that, Figure 4 In the illustrated embodiment, the energy storage device 121 includes a second pair of switches (S3, S4) for connecting the positive power line 31 and the negative power line 32, respectively. The control unit 20 is specifically configured to determine a first target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, instruct the first target energy storage device to control the second pair of switches (S3, S4) to turn on, and use the first rechargeable energy to recharge the first target energy storage device. The first voltage difference between the first target energy storage device and the energy storage device with the highest voltage is equal to or greater than a first threshold.

[0071] like Figure 4 As shown, in this embodiment, the second switch pair includes a third switch S3 and a fourth switch S4. The third switch S3 and the fourth switch S4 are specifically controlled by the Voltage Current Management System (VCMU) in the energy storage device 121. Here, when the control unit 20 determines the first target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, it can send a command to the VCMU of the first target energy storage device, instructing the VCMU of the first target energy storage device to control the third switch S3 and the fourth switch S4 to be turned on, thereby using the first rechargeable energy to recharge the first target energy storage device.

[0072] like Figure 4As shown in the illustration, in one embodiment, the second power branch 40 is connected to the sampling branch of the energy storage device 121. Here, the sampling branch includes a VCMU and a sampling circuit. The control unit 20 is specifically used to determine the second target energy storage device to be recharged from the energy storage device cluster 120 based on the voltage value of each energy storage device 121, and to recharge the second target energy storage device through the second power branch 40 using preset power. The second voltage difference between the second target energy storage device and the energy storage device with the highest voltage is equal to or greater than a second threshold, and the second threshold is less than a first threshold.

[0073] In this embodiment, the second threshold refers to the voltage difference value condition that triggers the second target energy storage device to be recharged through the second power branch 40, and it is also the condition for determining the second target energy storage device. That is, when the voltage difference between any two energy storage devices 121 in the energy storage device cluster 120 is equal to or greater than the second threshold, the second target energy storage device can be determined, and the second target energy storage device can be recharged through the second power branch 40.

[0074] It is easy to understand that when using preset electrical energy to replenish the second target energy storage device through the second power branch 40, the voltage and / or power of the preset electrical energy is less than the voltage and / or power of the first replenishing electrical energy. In practical use, since the second threshold is less than the first threshold, when the voltage difference between any two energy storage devices 121 in the energy storage device cluster 120 is equal to or greater than the first threshold, the voltage difference must also be greater than the second threshold. That is, when the first target energy storage device is determined, the first replenishing electrical energy with a larger voltage and / or power can be used to replenish the first target energy storage device through the first power branch 30. For example, the first threshold can be any voltage value between 1V and 1.5V. Taking the first threshold as V1 as an example, V1 satisfies: V1∈[1, 1.5]. When the voltage difference between any two energy storage devices 121 in the energy storage device cluster 120 is equal to or greater than the second threshold, that is, when the second target energy storage device is determined, a preset electrical energy with a lower voltage and / or lower power can be used to supplement the second target energy storage device through the second power branch 40. For example, the second threshold can be any voltage value between 0.3V and 1V. Taking the second threshold as V2 as an example, V2 satisfies: V2∈[0.3,1).

[0075] Figure 5 A schematic diagram of the specific structure of an inverter according to another embodiment of this application is shown. As an embodiment, it is related to... Figure 4 The difference in the illustrated embodiment is that, Figure 5 In the embodiment shown, the inverter 100 further includes a power supply unit 50.

[0076] In this embodiment, the power supply unit 50 is used to provide preset electrical energy. Here, the power supply unit 50 can be regarded as an auxiliary power source in the inverter 100. The preset electrical energy can be used to power each power-consuming unit in the inverter 100. In addition, the control unit 20 can also use the preset electrical energy to supplement the power of the second target energy storage device in the energy storage device cluster 120 through the second power branch 40.

[0077] Based on the above example, in a specific implementation, the power supply unit 50 may include a secondary DC-DC converter circuit. This secondary DC-DC converter circuit can be connected to the AC-DC converter circuit 11. The DC-DC converter circuit in the AC-DC converter circuit 11 steps down the DC power output from the AC-DC converter circuit and then outputs the stepped-down DC power to the secondary DC-DC converter circuit. The secondary DC-DC converter circuit can further step down the stepped-down DC power to obtain a low-voltage DC power corresponding to a preset energy level. For example, this low-voltage DC power can specifically be a DC power of 5.5V to 3.3V.

[0078] It is easy to understand that this low-voltage DC power, as a preset power source, can power the electrical components in the inverter 100. When the control unit 20 uses this preset power source to replenish the power of the second target energy storage device through the second power branch 40, it can specifically replenish the power of some of the battery cells in the second target energy storage device.

[0079] The above solution, by setting a power supply unit 50 in the inverter 100, provides a basis for replenishing power to the second target energy storage device through the second power branch 40. Furthermore, since the preset power provided by the power supply unit 50 can power the power-consuming units / devices in the inverter 100, it is possible to replenish power to the cells in the second target energy storage device without adding other power circuits by reusing the preset power provided by the power supply unit 50, thus providing a lower-cost and more efficient power replenishment solution.

[0080] This application also provides an energy storage system, including the inverter provided in any of the above embodiments, and X energy storage devices.

[0081] It is understood that the improvements and specific implementation methods of the energy storage system in this embodiment related to this application have already been... Figures 1 to 5 The corresponding embodiments are described in detail. In specific implementation, it can be... Figures 1 to 5 Based on the corresponding embodiment, the inverter 100 and the energy storage device 121 are configured in the energy storage system, so they will not be described in detail here.

[0082] This embodiment also provides a control method for an inverter, used to determine the inverter 100 in the above embodiment. It is understood that the execution entity of the inverter control method can be the control unit 20 in the inverter. In specific implementation, the inverter control method can be configured as a corresponding code program. By configuring this code program into the control unit of the inverter, the steps of the inverter control method can be executed.

[0083] Figure 6 A flowchart illustrating the implementation of an inverter control method according to an embodiment of this application is shown. The following is in conjunction with... Figure 6 This embodiment provides a detailed description of a control method for an inverter. For example... Figure 6 As shown, the control methods for the inverter include:

[0084] S110: Obtain the voltage value of each energy storage device through the second power branch.

[0085] In 110, the second power branch can be understood as the communication branch between the control unit and each energy storage device. This means that each energy storage device is equipped with a battery management system, which can obtain the voltage value of each cell in the energy storage device and calculate the voltage value of the energy storage device itself.

[0086] In practical implementation, the control unit connects to the battery management system in the energy storage device via the second power branch to obtain the voltage value of each energy storage device. Here, the second power branch can also refer to the branch connecting the inverter and the sampling branch of the energy storage device.

[0087] S120: Determine the target energy storage device to be recharged from the energy storage device cluster based on the voltage value of each energy storage device.

[0088] In 120, the target energy storage device generally refers to the energy storage device in the energy storage device cluster with a lower voltage value and a larger voltage difference between it and the energy storage device with the highest voltage.

[0089] In a specific implementation, when the control unit determines the target energy storage device from the energy storage device cluster based on the voltage value of each energy storage device, it can be done by comparing the voltage difference between each energy storage device.

[0090] For example, by comparing the voltage values ​​of each energy storage device, the energy storage device with the lowest voltage value can be selected as the target energy storage device.

[0091] For example, by calculating the pressure difference between each energy storage device, the energy storage device with the smaller voltage among the two energy storage devices with the largest pressure difference can be selected as the target energy storage device.

[0092] S130: Connect the power supply path to supply power to the target energy storage device; wherein, the power supply path includes a first power branch or a second power branch.

[0093] In 130, the first power branch and the second power branch are different supplementary power branches.

[0094] It should be noted that when using the first power branch as a charging path to charge the target energy storage device, the charging is applied to the entire target energy storage device cluster. That is, when using the first power branch as a charging path, one or more target energy storage devices in the cluster can be charged simultaneously. When using the second power branch as a charging path to charge the target energy storage device, if there are multiple target energy storage devices, they can be charged through the second power branch connected to each target energy storage device. It is worth noting that since the second power branch connects the control unit to the battery management system of the energy storage device, for a single target energy storage device, when the control unit activates the second power branch as a charging path, the second charging power output from the control unit to the second power branch can charge any single cell in the target energy storage device through the battery management system and cell circuit.

[0095] In this embodiment, since the first power branch is the branch connected to the DC side of the AC / DC conversion unit, and the second power branch can be understood as the communication branch between the control unit and each energy storage device, the replenishment voltage / replenishment power when using the first power branch as the replenishment path to replenish the target energy storage device is greater than the replenishment voltage / replenishment power when using the second power branch as the replenishment path to replenish the target energy storage device.

[0096] As an example, before step S130, the inverter control method further includes: instructing the energy storage device cluster to disconnect the series path between each energy storage device.

[0097] As an example, after step S130, the inverter control method further includes: instructing the energy storage device cluster to connect the series path between each energy storage device.

[0098] It is easy to understand that, since the inverter control method provided in this embodiment is applied to... Figures 1 to 5 The inverter provided in any embodiment is specifically applied to the control unit in the inverter. Therefore, the steps in the above embodiments can be specifically executed by the control unit in the inverter, and will not be described again here.

[0099] It is understood that the improvements and specific implementation methods of the energy storage system in this embodiment related to this application have already been... Figures 1 to 5The corresponding embodiments are described in detail. In specific implementation, it can be... Figures 1 to 5 The control method for the inverter provided in this embodiment is implemented based on the corresponding embodiment, so it will not be described in detail here.

[0100] Figure 7 This is a structural block diagram of an electronic device provided in an embodiment of this application. For example... Figure 7 As shown, the electronic device 7 of this embodiment includes: a processor 70, a memory 71, and a computer program 72 stored in the memory 71 and executable on the processor 70, such as a program for an inverter control method. When the processor 70 executes the computer program 72, it implements the steps of the various embodiments of the inverter control methods described above, for example... Figure 6 The steps shown are not repeated here.

[0101] For example, the computer program 72 can be divided into one or more units, which are stored in the memory 71 and executed by the processor 70 to complete this application. The one or more 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 72 in the electronic device 7. The electronic device may include, but is not limited to, the processor 70 and the memory 71. Those skilled in the art will understand that... Figure 7 This is merely an example of electronic device 7 and does not constitute a limitation on electronic device 7. It may include more or fewer components than shown, or combine certain components, or different components. For example, the electronic device may also include input / output devices, network access devices, buses, etc.

[0102] The processor 70 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.

[0103] The memory 71 can be an internal storage unit of the electronic device 7, such as a hard disk or memory of the electronic device 7. The memory 71 can also be an external storage device of the electronic device 7, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the electronic device 7. Furthermore, the memory 71 can include both internal and external storage units of the electronic device 7. The memory 71 is used to store the computer program and other programs and data required by the electronic device. The memory 71 can also be used to temporarily store data that has been output or will be output.

[0104] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 this application, and should all be included within the protection scope of this application.

Claims

1. An inverter, characterized by comprising: The inverter is connected between an alternating current (AC) source and a cluster of energy storage devices, the cluster of energy storage devices including at least X energy storage devices connected in series, X being an integer and X≥2, and the inverter including: an AC-DC conversion unit configured with an AC side connection end and a DC side connection end, the AC side connection end being configured to connect the AC source, and the DC side connection end being configured to connect a first power branch; a control unit connected to each of the energy storage devices through a second power branch; the control unit being configured to obtain a voltage value of each of the energy storage devices through the second power branch, determine a target energy storage device to be compensated from the cluster of energy storage devices based on the voltage value of each of the energy storage devices, and turn on a compensation path to compensate the target energy storage device, wherein the compensation path includes the first power branch or the second power branch.

2. The inverter of claim 1, wherein, the AC-DC conversion unit being configured to output first compensation power to the first power branch using AC power provided by the AC source.

3. The inverter of claim 2, wherein, the AC-DC conversion unit including an AC-DC conversion circuit configured with a positive connection end and a negative connection end; the first power branch including a positive power line and a negative power line, the positive power line being configured to connect the positive connection end and a positive electrode of each of the energy storage devices, and the negative power line being configured to connect the negative connection end and a negative electrode of each of the energy storage devices.

4. The inverter of claim 3, wherein, the first power branch further including a first switch pair configured to connect the energy storage devices; the control unit being specifically configured to determine a first target energy storage device to be compensated from the cluster of energy storage devices based on the voltage value of each of the energy storage devices, control a first switch pair connected to the first target energy storage device to be turned on, and compensate the first target energy storage device using the first compensation power; wherein a first voltage difference between the first target energy storage device and an energy storage device with the highest voltage is equal to or greater than a first threshold value.

5. The inverter of claim 3, wherein, the energy storage device including a second switch pair configured to connect the positive power line and the negative power line, respectively; the control unit being specifically configured to determine a first target energy storage device to be compensated from the cluster of energy storage devices based on the voltage value of each of the energy storage devices, instruct the first target energy storage device to control the second switch pair to be turned on, and compensate the first target energy storage device using the first compensation power; wherein a first voltage difference between the first target energy storage device and an energy storage device with the highest voltage is equal to or greater than a first threshold value.

6. The inverter according to claim 4 or 5, characterized by the second power branch being connected to a sampling branch of the energy storage device; the control unit being specifically configured to determine a second target energy storage device to be compensated from the cluster of energy storage devices based on the voltage value of each of the energy storage devices, and compensate the second target energy storage device using preset power through the second power branch; wherein a second voltage difference between the second target energy storage device and an energy storage device with the highest voltage is equal to or greater than a second threshold value, and the second threshold value is less than the first threshold value.

7. The inverter according to any one of claims 1 to 5, characterized by The control unit is further configured to instruct the cluster of energy storage devices to disconnect the series connection between the energy storage devices before the power supply path is turned on to supply power to the target energy storage device.

8. An energy storage system characterized by, The inverter of any one of claims 1 to 7, and X energy storage devices.

9. A control method of an inverter, characterized by, The control method of the inverter of any one of claims 1 to 7, comprising: obtaining a voltage value of each of the energy storage devices via the second power branch; determining a target energy storage device to be supplied with power from the cluster of energy storage devices based on the voltage value of each of the energy storage devices; turning on the power supply path to supply power to the target energy storage device; wherein the power supply path comprises the first power branch or the second power branch.

10. The control method of the inverter according to claim 9, characterized by, The control method of the inverter of any one of claims 1 to 7, further comprising, before the step of turning on the power supply path to supply power to the target energy storage device: instructing the cluster of energy storage devices to disconnect the series connection between the energy storage devices; and / or The control method of the inverter of any one of claims 1 to 7, further comprising, after the step of turning on the power supply path to supply power to the target energy storage device: instructing the cluster of energy storage devices to connect the series connection between the energy storage devices.

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