ENERGY STORAGE SYSTEM, CONTROL METHOD FOR ENERGY STORAGE SYSTEM, AND SOLAR POWER GENERATION SYSTEM

Abstract

The present application relates to the field of power supply technology and discloses an energy storage system, a control method for the energy storage system, and a photovoltaic power generation system. The energy storage system includes a battery cluster, a power conversion circuit, and a controller. An output end of the battery cluster is connected to a first terminal of the power conversion circuit, and a second terminal of the power conversion circuit is connected to an output end of the energy storage system. The power conversion circuit converts a direct current provided by the battery cluster into an alternating current and transmits the alternating current to an AC power grid, or converts an alternating current obtained from the second terminal of the power conversion circuit into a direct current for charging the battery cluster. Each battery cluster includes at least two energy storage modules connected in series, each energy storage module includes a bypass circuit and a battery pack, and each battery pack includes a plurality of batteries. The controller controls each bypass circuit based on a first parameter value of each battery pack so that the electric quantity of the battery pack is in a balanced state. Based on the energy storage system, the electric quantity of the battery pack can be in a balanced state, whereby the impact on the current of the battery class is reduced and the waste of the electric quantity is reduced.

Description

[Technical field]

[0001] The present application relates to the field of power supply technology, in particular to an energy storage system, a control method for an energy storage system, and a solar power generation system. [Background technology]

[0002] As energy shortage and environmental pollution worsen in modern society, currently, power generation methods such as photovoltaic power generation and wind power generation are used on a large scale. The fluctuation and uncertainty characteristics of such new energy are increasingly prominent, and it is difficult to meet the requirements of continuous power supply on the user side. However, as electrochemical cell technology develops and production capacity increases rapidly, the cost of electrochemical cells decreases, which provides the opportunity for electrochemical cells to participate in the power energy storage of new energy power generation systems. In addition, the energy storage system using electrochemical cells has characteristics such as flexibility, charge and discharge controllability, fast response ability, and high energy density, so that the energy storage system using electrochemical cells is gradually and widely used on the power generation side.

[0003] By adding an energy storage system using electrochemical cells on the generation side, the excess electrical energy not consumed during periods of high energy yield or low power consumption can be stored and discharged during periods of low energy yield or high power consumption, so that the generation tends to be stable and the input to the AC power grid can be reduced. influence teeth Mitigation will be done.

[0004] In an energy storage system using electrochemical cells, in order to increase the backup capacity and meet the voltage level requirements of the power generation system, multiple battery packs are generally connected in series to form a battery cluster with high voltage and large capacity. Each battery pack includes multiple battery cells connected in series or in a series and parallel connection manner. Since the state of health (SOH) or original state of charge (SOC) of the batteries are different, the amount of electricity in the battery packs is unbalanced. As a result, the time to fully charge or discharge the battery packs is different. Specifically, when multiple battery packs are connected in series to form a battery cluster, the current of all the battery packs is the same, so the total current of the battery cluster needs to be limited based on the minimum current of the battery packs. As a result, a battery pack with a large amount of electricity remaining cannot be fully discharged, and a battery pack with a small amount of electricity remaining cannot be fully charged. Therefore, the amount of electricity in the battery packs cannot be fully used, thereby limiting the current of the battery cluster and wasting the amount of electricity. [Prior art document] [Patent documents] [Patent Document 1] Chinese Patent Application No. 104953659 [Patent Document 2] Chinese Patent Application No. 102856942 Summary of the Invention

[0005] The present application provides an energy storage system, a control method for the energy storage system, and a solar power generation system, so that the electrical energy of the battery pack can be in balance, thereby reducing the impact on the current of the battery cluster and further reducing the waste of electrical energy.

[0006] According to a first aspect, the present application provides an energy storage system. The energy storage system is applied to a new energy generation scenario. An output of the energy storage system is connected to an AC power grid, thereby providing a power supply to the AC power grid. influence of Mitigation In order to achieve this, the battery cluster can store excess electric energy that is not consumed during periods of high energy yield or low power consumption, and discharge during periods of low energy yield or high power consumption. The energy storage system includes a battery cluster, a power conversion circuit, and a controller. An output end of the battery cluster is connected to a first terminal of the power conversion circuit, and a second terminal of the power conversion circuit is connected to an output end of the energy storage system. The power conversion circuit is configured to convert a direct current provided by the battery cluster to an alternating current, and transmit the alternating current to an AC power grid, or convert an alternating current obtained from the second terminal of the power conversion circuit to a direct current for charging the battery cluster. When the power conversion circuit charges the battery cluster, the alternating current may be provided by an AC power grid, or may be provided by a new energy generation device. Each battery cluster includes at least two energy storage modules connected in series, each energy storage module includes a bypass circuit and a battery pack, each battery pack includes multiple batteries, and the multiple batteries in the battery pack may be connected in series or in a series and parallel connection manner. The controller controls each bypass circuit based on a first parameter value of each battery pack such that the electrical quantities of the battery packs are in balance.

[0007] According to the energy storage system provided in the present application, each battery pack in the battery cluster is correspondingly connected to one bypass circuit, and the controller controls each bypass circuit according to the first parameter value of each battery pack to allow the battery pack to be bypassed from the battery cluster. When the battery cluster is charged, the bypassed battery pack stops charging first. As the battery pack is gradually bypassed, the electrical quantities of the battery packs in the battery cluster are synchronized. When the battery cluster is discharged, the bypassed battery pack stops discharging first. As the battery pack is gradually bypassed, the electrical quantities of the battery packs in the battery cluster are also synchronized. However, after the battery pack is bypassed, the remaining battery pack can still be charged or discharged at the maximum current. Thus, the current of the battery cluster can remain unchanged. In short, the energy storage system can balance the electrical quantities of the battery packs, thereby reducing the impact on the current of the battery cluster and further reducing the waste of electrical quantities. Furthermore, since the electrical quantities of the battery packs are in balance, the maximum backup period is further realized.

[0008] The controller may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), a digital signal processor (DSP), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0009] The controller may be a single stage controller or a multi-stage controller. When the controller is a multi-stage controller, a higher-level controller may control a lower-level controller, and there may be multiple lower-level controllers. The multi-stage controller may be integrated on a Printed circuit board (PCB) or may be physically divided into multiple parts and placed separately on the PCB at different locations of the energy storage system. The parts cooperate to implement a control function.

[0010] In a possible implementation, the controller is specifically configured to control each bypass circuit to bypass a battery pack whose first parameter value is equal to or greater than a first preset parameter value when the battery cluster is being charged, in which case the remaining battery packs continue to be charged, or to control each bypass circuit to bypass a battery pack whose first parameter value is equal to or less than a second preset parameter value when the battery cluster is being discharged, in which case the remaining battery packs continue to be discharged. After a battery pack is bypassed, the remaining battery pack can still be charged or discharged at a maximum current. Thus, the current of the battery cluster can remain unchanged.

[0011] In a possible implementation, the bypass circuit includes a first controllable switch and a second controllable switch, the positive output terminal of the battery pack is connected to a first terminal of the first controllable switch, the second terminal of the first controllable switch is connected to a first terminal of the second controllable switch and to a positive output terminal of the energy storage module, and the second terminal of the second controllable switch is connected to a first terminal of the second controllable switch and to a positive output terminal of the energy storage module. Energy Storage The negative output of the battery pack is connected to the negative output of the energy storage module, and the negative output of the battery pack is connected to the negative output of the energy storage module.

[0012] In a possible implementation, the controller is specifically configured to initially control both the first controllable switch and the second controllable switch to be open, and after a first preset time, control the second controllable switch to be closed to bypass the battery pack. When both the first controllable switch and the second controllable switch are power switch devices, the first preset time is longer than or equal to the dead time of the first controllable switch, so as to avoid a short circuit between the positive output terminal and the negative output terminal of the battery pack caused by the simultaneous closing of the first controllable switch and the second controllable switch.

[0013] In a possible implementation, the controller is specifically configured to, when the battery cluster is being charged, sequentially bypass battery packs whose first parameter value is equal to or greater than the first preset parameter value until only one remaining battery pack is not bypassed, which indicates that charging of the battery cluster is completed in this case and the only remaining battery pack is not bypassed any more. The controller is specifically configured to, when the battery cluster is being discharged, sequentially bypass battery packs whose first parameter value is equal to or less than the second preset parameter value until only one remaining battery pack is not bypassed, which indicates that discharging of the battery cluster is completed in this case and the only remaining battery pack is not bypassed any more.

[0014] In a possible implementation, the controller is further configured to control each bypass circuit to reconnect the bypassed battery pack to the battery cluster when the battery cluster is charged and the first parameter value of the only remaining battery pack is greater than or equal to a first preset parameter value, or to control each bypass circuit to reconnect the bypassed battery pack to the battery cluster when the battery cluster is discharged and the first parameter value of the only remaining battery pack is less than or equal to a second preset parameter value.

[0015] In a possible implementation, the controller is specifically configured to first control both the first controllable switch and the second controllable switch to open, and after a second preset time, control the first controllable switch to close so that the battery pack reconnects to the battery cluster. When both the first controllable switch and the second controllable switch are power switch devices, the second preset time is longer than or equal to the dead time of the second controllable switch, so as to avoid a short circuit between the positive output terminal and the negative output terminal of the battery pack caused by the simultaneous closing of the first controllable switch and the second controllable switch.

[0016] In a possible implementation, the power conversion circuit includes a DC / DC conversion circuit and a DC / AC conversion circuit. A first terminal of the DC / DC conversion circuit is the first terminal of the power conversion circuit, a second terminal of the DC / DC conversion circuit is connected to the first terminal of the DC / AC conversion circuit, and a second terminal of the DC / AC conversion circuit is the second terminal of the power conversion circuit. The DC / DC conversion circuit is configured to perform DC conversion on the DC provided by the battery cluster, and then transmit the DC obtained through the DC conversion to the DC / AC conversion circuit, or to perform DC conversion on the DC provided by the DC / AC conversion circuit, and then transmit the DC obtained through the DC conversion to the battery cluster. The DC / AC conversion circuit is configured to convert the DC provided by the DC / DC conversion circuit to AC, or to convert the obtained AC to DC, and then transmit the DC to the DC / DC conversion circuit. The controller is further configured to control the DC / DC conversion circuitry to deactivate prior to bypassing or connecting to the battery pack.

[0017] In a possible implementation, the energy storage system further includes a soft start circuit, and a positive port of the output end of the battery cluster is connected to a positive port of the first terminal of the DC / DC conversion circuit through the soft start circuit, or a negative port of the output end of the battery cluster is connected to a negative port of the first terminal of the DC / DC conversion circuit through the soft start circuit. The soft start circuit includes a first relay, a second relay, and a first resistor. The first relay is connected in series to the first resistor and then in parallel to the second relay. The controller is further configured to control the first relay and the second relay to open before bypassing or connecting the battery pack to the battery pack.

[0018] In a possible implementation, the controller is further configured to, after completing the bypass or connection of the battery pack, control the voltage at the first terminal of the DC / DC conversion circuit to be equal to the output voltage of the battery cluster, and control the second relay to be closed. A bus capacitor is usually disposed at the first terminal of the DC / DC conversion circuit. The controller controls the voltage at the first terminal of the DC / DC conversion circuit to be equal to the output voltage of the battery cluster, so that the voltage of the bus capacitor is equal to the output voltage of the battery cluster, and also controls the second relay to be closed. In this case, the voltage of the bus capacitor is supplied to the battery cluster. Unaffected thereby protecting the battery cluster.

[0019] In a possible implementation, the controller is further configured to control the first relay to be closed and the second relay to be open after completing the bypass or connection of the battery pack, and to control the first relay to be open and the second relay to be closed after a third preset time.

[0020] The third preset time is for achieving potential equalization and for the battery cluster to influenceAfter current limiting is performed using a first relay and a first resistor to reduce the current, charging and discharging are set to occur between the first terminal of the DC / DC conversion circuit and the output end of the battery cluster.

[0021] In a possible implementation, the controller includes a first controller and at least two second controllers. The second controllers are connected to the battery packs in a one-to-one correspondence. The second controllers are configured to obtain second parameter values ​​of the corresponding battery packs and send the second parameter values ​​to the first controller. The first controller is configured to determine first parameter values ​​of all the battery packs based on the second parameter values ​​of all the battery packs, determine battery packs whose first parameter values ​​are equal to or greater than a first preset parameter value as bypass target battery packs when the battery cluster is being charged, or determine battery packs whose first parameter values ​​are equal to or less than the second preset parameter value as bypass target battery packs when the battery cluster is being discharged, and send a control command to the second controller. The control command is used to instruct the corresponding second controller to control the bypass circuit to bypass the bypass target battery pack.

[0022] The second controller is a Battery Monitoring Unit (BMU), and the first controller is a Battery Control Unit (BCU).

[0023] In a possible implementation, the second parameter value includes a total capacity of the battery pack, a state of energy SOE value, and a state of health SOH value, and the first parameter value is a state of charge SOC value.

[0024] In a possible implementation, the controller includes a first controller and at least two second controllers, the second controllers being connected to the battery packs in a one-to-one correspondence, the second controllers being configured to obtain first parameter values ​​of the corresponding battery packs and transmit the first parameter values ​​to the first controllers.

[0025] The first controller determines a battery pack whose first parameter value is equal to or greater than a first preset parameter value as a bypass target battery pack when the battery cluster is charged, or determines a battery pack whose first parameter value is equal to or less than a second preset parameter value as a bypass target battery pack when the battery cluster is discharged, and sends a control command to the second controller, where the control command is used to instruct the corresponding second controller to control a bypass circuit to bypass the bypass target battery pack.

[0026] In a possible implementation, the first parameter value is a voltage value or a state of charge SOC value.

[0027] According to a second aspect, the present application further provides a method of controlling an energy storage system, the method being applied to an energy storage system provided in the above implementations, the method comprising: Controlling each bypass circuit based on a first parameter value of each battery pack such that the electrical quantities of the battery packs are in balance.

[0028] Based on the above control method, the electric quantity of the battery packs can be in a balanced state. After the fully charged or discharged battery pack is separated, the other battery packs can be charged or discharged at a maximum current, thereby mitigating the impact on the current of the battery cluster. Furthermore, since the electric quantity of the battery packs is in a balanced state, the maximum backup period is further realized. Furthermore, when it is determined that the battery is abnormal, the bypass circuit may be controlled to bypass the battery pack that is found to be abnormal, in order to repair the malfunction and ensure that the remaining battery packs can continue to operate normally.

[0029] In one possible implementation, controlling each bypass circuit based on the first parameter value of each battery pack includes: controlling each bypass circuit to bypass a battery pack having a first parameter value equal to or greater than a first preset parameter value when the battery cluster is being charged; controlling each bypass circuit to bypass a battery pack having a first parameter value less than or equal to a second preset parameter value when the battery cluster is discharged; In particular:

[0030] In a possible implementation, controlling each bypass circuit to bypass a battery pack having a first parameter value equal to or greater than a first preset parameter value when the battery cluster is being charged includes: Specifically including, when the battery cluster is being charged, sequentially bypassing the battery packs whose first parameter value is equal to or greater than the first preset parameter value until only one remaining battery pack is not bypassed; or controlling each bypass circuit to bypass a battery pack having a first parameter value less than or equal to a second preset parameter value when the battery cluster is discharged; Specifically, when the battery cluster is discharged, bypassing the battery packs having a first parameter value less than or equal to the second preset parameter value in sequence until only one remaining battery pack is not bypassed.

[0031] In a possible implementation, the method comprises: controlling each bypass circuit to reconnect a bypassed battery pack to the battery cluster when the battery cluster is being charged and the first parameter value of only one remaining battery pack is greater than or equal to the first preset parameter value; or controlling each bypass circuit to reconnect the bypassed battery pack to the battery cluster when the battery cluster is discharged and the first parameter value of only one remaining battery pack is less than or equal to a second preset parameter value; Further includes.

[0032] In a possible implementation, the method comprises: Before bypassing or connecting the battery pack, control a DC / DC conversion circuit connected to an output end of the battery cluster to stop operating, and a first terminal of the DC / DC conversion circuit is connected to the output end of the battery cluster; and After completing the bypass or connection of the battery pack, control the voltage at the first terminal of the DC / DC conversion circuit to be equal to the output voltage of the battery cluster, and control the DC / DC conversion circuit to start operating. Further includes.

[0033] In a possible implementation, the method comprises: Obtaining second parameter values ​​corresponding to all of the battery packs; determining first parameter values ​​for all of the battery packs based on second parameter values ​​corresponding to all of the battery packs; Further includes.

[0034] In a possible implementation, the second parameter value includes a total capacity of the battery pack, a state of energy SOE value, and a state of health SOH, and the first parameter value is a state of charge SOC value.

[0035] In a possible implementation, the first parameter value is a voltage value or a state of charge SOC value.

[0036] According to a third aspect, the present application further provides a photovoltaic power generation system, which includes the energy storage system provided in the above implementation, and further includes a photovoltaic power end. The output end of the photovoltaic power end is configured to connect to an AC power grid. The photovoltaic power end is configured to generate AC by using light energy. The AC can be transmitted to the AC power grid or can charge a battery cluster after passing through a power conversion circuit of the energy storage system.

[0037] According to a fourth aspect, the present application further provides a solar power generation system, the solar power generation system including the energy storage system provided in the above implementation, further comprising: Photovoltaic Module The solar power generation module is configured to generate direct current by using light energy to charge the battery cluster.

[0038] Each battery pack in the battery cluster of the photovoltaic power generation system provided in the present application is correspondingly connected to one bypass circuit, and the controller controls each bypass circuit based on the first parameter value of each battery pack to allow the battery pack to be bypassed from the battery cluster. When the battery cluster is charged, the bypassed battery pack stops charging first. As the battery pack is gradually bypassed, the electrical quantities of the battery packs in the battery cluster are synchronized. When the battery cluster is discharged, the bypassed battery pack stops discharging first. As the battery pack is gradually bypassed, the electrical quantities of the battery packs in the battery cluster are also synchronized. However, after the battery pack is bypassed, the remaining battery pack can still be charged or discharged at the maximum current. Thus, the current of the battery cluster can remain unchanged. In short, the photovoltaic power generation system can balance the electrical quantities of the battery packs, thereby reducing the impact on the current of the battery cluster and further reducing the waste of electrical quantities. Furthermore, since the electrical quantities of the battery packs are in a balanced state, the maximum backup period is further realized. [Brief description of the drawings]

[0039] [Figure 1] 1 is a schematic diagram of a new energy power generation system according to an embodiment of the present application; [Diagram 2] FIG. 1 is a schematic diagram of an energy storage system according to an embodiment of the present application. [Diagram 3] FIG. 1 is a schematic diagram of a battery cluster according to an embodiment of the present application. [Figure 4] FIG. 2 is a schematic diagram of another battery cluster according to an embodiment of the present application. [Diagram 5] FIG. 2 is a schematic diagram of another energy storage system according to an embodiment of the present application. [Figure 6] FIG. 2 is a schematic diagram of yet another energy storage system according to an embodiment of the present application. [Figure 7] 4 is a flowchart of a method for determining a charge / discharge state of a battery pack according to an embodiment of the present application. [Figure 8A] FIG. 2 is a schematic diagram of a method for controlling an energy storage system according to an embodiment of the present application. [Figure 8B] FIG. 2 is a schematic diagram of a method for controlling an energy storage system according to an embodiment of the present application. [Figure 9] FIG. 2 is a schematic diagram of another method for controlling an energy storage system according to an embodiment of the present application. [Figure 10] FIG. 13 is a schematic diagram of yet another method for controlling an energy storage system, according to an embodiment of the present application. [Figure 11] 1 is a schematic diagram of a solar power generation system according to an embodiment of the present application. [Figure 12] FIG. 2 is a schematic diagram of another solar power generation system according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In order to enable people skilled in the art to better understand the technical solutions provided in the embodiments of the present application, application scenarios of the technical solutions of the present application are first described below.

[0041] FIG. 1 is a schematic diagram of a new energy power generation system according to an embodiment of the present application.

[0042] The new energy power generation system includes a battery cluster 10, a power conversion circuit 20, a new energy power generation end 30, and a load 40.

[0043] The new energy power generation end 30 is configured to output AC. Because the new energy power generation end 30 has the characteristics of fluctuation and uncertainty, the energy yield of the new energy power generation end 30 fluctuates. When the AC output by the new energy power generation end 30 is higher than the power consumption demand of the AC power grid 50, the power conversion circuit 20 converts the surplus electricity into DC to charge the battery cluster 10. When the AC output by the new energy power generation end 30 is lower than the power consumption demand of the AC power grid 50, the power conversion circuit 20 converts the DC output by the battery cluster 10 into AC, and then outputs the AC to the AC power grid 50, so that the AC power grid 50 tends to be stable.

[0044] For example, the new energy power generation end 30 is a photovoltaic power generation end. The new energy power generation end 30 includes a photovoltaic power generation module and a direct current (DC) / alternating current (AC) conversion circuit (sometimes called an inverter circuit or inverter). The photovoltaic power generation module generates direct current by using light energy. The DC / AC conversion circuit converts the direct current into alternating current, and then outputs the alternating current to the AC power grid 50 and / or charges the battery cluster 10.

[0045] The load 40 is an electric device of a new energy power generation system, which is not particularly limited in the present application.

[0046] The battery cluster 10 includes a plurality of battery packs, each of which includes a plurality of battery cells connected in series or in a series and parallel connection manner. Since the SOH or original SOC of the batteries are different, the electric quantity of the battery packs is unbalanced. As a result, the time to fully charge or discharge the battery packs is different. Specifically, when a plurality of battery packs are connected in series to form a battery cluster, the current of all the battery packs is the same, so the total current of the battery cluster needs to be limited based on the minimum current of the battery packs. As a result, the battery pack with a large electric quantity cannot be fully discharged, and the battery pack with a small electric quantity cannot be fully charged. Therefore, the electric quantity of the battery packs cannot be fully used, thereby limiting the current of the battery cluster and wasting the electric quantity. During the next charge or discharge, the battery cluster cannot achieve the maximum backup period due to the electric quantity of the battery packs being unbalanced.

[0047] In order to solve the above technical problems, the present application provides an energy storage system, a control method for the energy storage system, and a photovoltaic power generation system. Each battery pack in a battery cluster of the energy storage system is connected to one bypass circuit accordingly. A controller controls each bypass circuit based on a first parameter value of each battery pack to allow the battery pack to be bypassed from the battery cluster, thereby balancing the electric quantity of the battery packs. After a battery pack is bypassed, the remaining battery packs can still be charged or discharged at a maximum current. Thus, the current of the battery cluster can remain unchanged. Based on the energy storage system, the electric quantity of the battery packs can be in a balanced state, thereby reducing the impact on the current of the battery cluster, reducing the waste of electric quantity, and further realizing the maximum backup period.

[0048] In order to make those skilled in the art understand the technical solutions of the present application more clearly, the following describes the technical solutions of the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application.

[0049] Terms such as "first" and "second" in the specification of this application are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or the quantity of the technical features depicted.

[0050] In this application, unless expressly specified and limited otherwise, the term "connection" should be understood in a broad sense, for example, the connection may be a fixed connection, a detachable connection, or an integral connection, or may be a direct connection or an indirect connection based on an intermediate medium.

[0051] Please refer to both Figures 2 and 3. Figure 2 is a schematic diagram of an energy storage system according to an embodiment of the present application. Figure 3 is a schematic diagram of a battery cluster according to an embodiment of the present application.

[0052] The energy storage system includes a battery cluster 10, a power conversion circuit 20, and a controller 100.

[0053] An output of the battery cluster 10 is connected to a first terminal of a power conversion circuit 20. A second terminal of the power conversion circuit 20 is connected to an output of an energy storage system and is configured to output electrical energy for an AC power grid.

[0054] The power conversion circuit 20 is configured to convert the direct current supplied by the battery cluster 10 into alternating current, and then transmit the alternating current to the AC power grid 50, or convert the alternating current obtained from the second terminal of the power conversion circuit 20 into direct current for charging the battery cluster. That is, the power conversion circuit 20 can implement bidirectional power conversion, and may charge the battery cluster 10 by using the alternating current supplied by the AC power grid or the new energy generation end, or may supply power to the AC power grid 50 by using the direct current output by the battery cluster 10.

[0055] As shown in Figure 3, each battery cluster 10 includes at least two energy storage modules connected in series. In the figure, the energy storage modules are designated 10a1 to 10a m It is represented by:

[0056] Each energy storage module includes a bypass circuit and a battery pack, and each battery pack includes multiple batteries.

[0057] For example, the energy storage module 10a1 includes a bypass circuit 101b1 and a battery pack 101a1.

[0058] The batteries in each battery pack may be connected in series or in a series and parallel connection manner, which is not particularly limited in this embodiment of the present application. In FIG. 3 and the following description, the batteries in the battery pack are connected in series as an example.

[0059] The bypass circuit of this embodiment of the present application includes two working states. In the first working state, the corresponding battery pack is not bypassed, so that the corresponding battery pack can be connected in series to the battery cluster. In the second working state, the corresponding battery pack is bypassed, that is, the battery pack is equivalently disconnected from the battery cluster. Specifically, when the battery cluster is in a charging state, the battery pack stops charging after being bypassed, or when the battery cluster is in a discharging state, the battery pack stops discharging after being bypassed.

[0060] The first parameter value may represent the electrical quantity of the battery pack. The controller 100 may determine the electrical quantity of the corresponding battery pack based on the first parameter value, and control the bypass circuit to switch between the aforementioned two working states, so that the electrical quantity of the battery pack is in a balanced state.

[0061] The aforementioned controller may be an ASIC, a PLD, a DSP, or a combination thereof. The PLD may be a CPLD, an FPGA, a GAL, or any combination thereof, which is not particularly limited in this embodiment of the present application.

[0062] The controller in the above description of this embodiment of the present application may be a single-stage controller or a multi-stage controller. When the controller is a multi-stage controller, the upper controller may receive information sent by the lower controller, and there may be multiple lower controllers, and the upper controller may control the lower controllers. The multi-stage controller may be independently integrated on a printed circuit board (PCB), or may be physically divided into multiple parts and separately placed on the PCB at different positions of the energy storage system. The parts cooperate to implement a control function. This is not particularly limited in this embodiment of the present application.

[0063] The battery cells in the battery pack may be of types such as lithium ion batteries, lead acid batteries, supercapacitors, or combinations of these types, which is not particularly limited in this embodiment of the present application.

[0064] Based on the energy storage system provided in this embodiment of the present application, when the battery cluster is charged, the bypassed battery pack stops charging first. As the battery pack is gradually bypassed, the electrical quantities of the battery packs in the battery cluster are synchronized. When the battery cluster is discharged, the bypassed battery pack stops discharging first. As the battery pack is gradually bypassed, the electrical quantities of the battery packs in the battery cluster are also synchronized. After the battery pack is bypassed, the remaining battery pack can still be charged or discharged at the maximum current. Thus, the current of the battery cluster can remain unchanged. In summary, the energy storage system can balance the electrical quantities of the battery packs, thereby reducing the impact on the current of the battery cluster and reducing the waste of electrical quantities. Moreover, since the electrical quantities of the battery packs are in balance, the maximum backup period is further realized.

[0065] Below, a description will be given with reference to a specific implementation of the energy storage system.

[0066] FIG. 4 is a schematic diagram of another battery cluster according to an embodiment of the present application.

[0067] The controller in the figure is a two-stage controller, i.e. First Controller 1001 and Second Controller Includes 1002a1~1002am.

[0068] The number of second stage controllers is the same as the number of battery packs. The second stage controllers are connected to the battery packs in a one-to-one correspondence. Each second controller is connected to a first controller 1001, and each second controller can communicate with the first controller 1001.

[0069] Each bypass circuit in the figure includes a first controllable switch and a second controllable switch. Energy StorageWhen including the module, the first controllable switches in the battery cluster are S11-Sm1, and the second controllable switches in the battery cluster are S12-Sm2.

[0070] The energy storage module 10a1 is used as an example. The first controllable switch is S11, and the second controllable switch is S12. The positive output terminal of the battery pack 101a1 is connected to the first terminal of the first controllable switch S11, the second terminal of the first controllable switch S11 is connected to the first terminal of the second controllable switch S12 and the positive output terminal of the energy storage module 10a1, and the second terminal of the second controllable switch S12 is connected to the first terminal of the second controllable switch S12 and the positive output terminal of the energy storage module 10a1. Energy Storage Module 10a1 and the negative output terminal of the battery pack 101a1 is connected to the negative output terminal of the energy storage module 10a1.

[0071] Similarly, S21 and S22 are batteries pack 101a2, and by analogy, Sm1 and Sm2ha batteries pack 101a m Corresponds to.

[0072] each Energy Storage The first controllable switch and the second controllable switch in the module may be an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MFET), or a semiconductor field effect transistor (SFET). - Oxide Semiconductor Field- Effect Transistor, MOSFET, Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor - Oxide Semiconductor Field-Effect Transistor, SiC MOSFET), mechanical switch, a combination thereof, etc. The second controller controls the operation state of the second controller by sending a control signal to the first controllable switch and the second controllable switch. In a possible implementation, the control signal is a Pulse Width Modulation (PWM) signal.

[0073] For example, the first controllable switch and the second controllable switch are both N-type MOSFETs. In this case, the first terminal of each of the first controllable switch and the second controllable switch is a drain, and the second terminal of each of the first controllable switch and the second controllable switch is a gate. The direction of the body diode of S11 is opposite to the direction of the battery voltage, and the direction of the body diode of S12 is opposite to the direction of the body diode of S11. Energy Storage The module is not directly shorted using the body diode.

[0074] In some other embodiments, an additional diode connected in parallel may also be used to replace the body diode of the switch device.

[0075] The aforementioned switch device is Energy Storage It may be located in the module, integrated with the second controller, or designed independently on a PCB and integrated in or outside the battery pack, which is not particularly limited in this embodiment of the present application.

[0076] In some embodiments, the second controller is a battery monitoring unit and the first controller is a battery control unit.

[0077] The controller is specifically configured to control each bypass circuit to bypass a battery pack whose first parameter value is equal to or greater than a first preset parameter value when the battery cluster is being charged, or to control each bypass circuit to bypass a battery pack whose first parameter value is equal to or less than a second preset parameter value when the battery cluster is being discharged. The operating principle of the controller will be described in detail below.

[0078] The following will first describe a first implementation of the control of the bypass circuit.

[0079] Each second controller obtains second parameter values ​​of the corresponding battery pack and sends the second parameter values ​​to the first controller, the second parameter values ​​including a total capacity Q, a State of Energy (SOE) value, and a State of Health (SOH) value of the battery pack.

[0080] The SOE value represents the current controllable amount of electricity in the battery pack. value represents the capacity of the current battery pack for storing electrical energy relative to the new battery pack, expressed in the form of a percentage, and may be understood as the ratio of the current available capacity to the total capacity Q.

[0081] The first controller controls all the battery packs based on the acquired second parameter values ​​of all the battery packs. pack and determining a battery pack whose first parameter value is equal to or greater than a first preset parameter value as a bypass target battery pack if the battery cluster is being charged, or determining a battery pack whose first parameter value is equal to or less than a second preset parameter value as a bypass target battery pack if the battery cluster is being discharged.

[0082] The first parameter value is a State of Charge (SOC) value. The first preset parameter value and the second preset parameter value are preset and stored in the first controller based on the actual situation, and are called when the first preset parameter value and the second preset parameter value should be used. The first preset parameter value and the second preset parameter value are not particularly limited in this embodiment of the present application.

[0083] Specifically, the first controller is configured as follows: SOC=SOE / (Q / SOH) (1) The SOC value may be determined according to:

[0084] The SOC obtained by Eq. (1) value is the actual SOC of the battery pack, i.e., the ratio of the current amount of electricity to the current capacity.

[0085] The first controller then sends a control command to the second controller, and the control command is used to instruct the corresponding second controller to control the bypass circuit to bypass the bypass target battery pack.

[0086] For example, when the battery pack 101a1 is determined to be a bypass target battery pack, the control command sent by the first controller is used to instruct the second controller 1002a1 to control S11 and S12 so as to bypass the battery pack 101a1.

[0087] When the battery pack 101a1 is normally connected in series to the battery cluster, the first controllable switch S11 is closed and the second controllable switch S12 is open. When bypassing the battery pack 101a1, the second controller 1002a1 first controls both the first controllable switch S11 and the second controllable switch S12 to be open, and after a first preset time, controls the second controllable switch S12 to be closed.

[0088] The first preset time is longer than or equal to the dead time of the first controllable switch S11, so as to avoid a short circuit between the positive output terminal and the negative output terminal of the battery pack 101a1 caused by the simultaneous closing of the first controllable switch S11 and the second controllable switch S12. The first preset time is not particularly limited in this embodiment of the present application.

[0089] The principle of bypassing other battery packs is similar, and the details will not be described here again in this embodiment of the present application.

[0090] When the battery cluster is charged, the electric power of the battery packs is unbalanced, so the time period for fully charging the battery packs may be different. The first controller sequentially determines the battery packs whose first parameter value is equal to or greater than the first preset parameter value as bypass target battery packs, and sends a control command to the second controller, so that the second controller controls the bypass circuit to sequentially bypass the bypass target battery packs until only one remaining battery pack is not bypassed. In this case, the electric power of the other bypassed battery packs is in a balanced state.

[0091] In this case, only one remaining battery pack continues to be charged. When the first controller determines that the first parameter value of the only remaining battery pack is equal to or greater than the first preset value, it indicates that the charging of the battery cluster is completed in this case. The only remaining battery pack is no longer bypassed. Meanwhile, the second controller controls all bypassed battery packs to be reconnected to the battery cluster.

[0092] When the battery cluster is discharged, the electric charge of the battery packs may be unbalanced, so that the time period for fully discharging the battery packs may be different. The first controller sequentially determines the battery packs whose first parameter value is equal to or less than the second preset parameter value as bypass target battery packs, and sends a control command to the second controller, so that the second controller controls the bypass circuit to sequentially bypass the bypass target battery packs until only one remaining battery pack is not bypassed. In this case, the electric charge of the other bypassed battery packs is in a balanced state.

[0093] Only one remaining battery pack continues to be discharged. When the first controller determines that the first parameter value of the only remaining battery pack is equal to or less than the second preset value, it indicates that the discharging of the battery cluster is completed in this case. The only remaining battery pack is no longer bypassed. Meanwhile, the second controller controls all bypassed battery packs to be reconnected to the battery cluster.

[0094] For example, the battery pack 101a1 is reconnected to the circuit. When the battery pack 101a1 is in a bypassed state, the first controllable switch S11 is open and the second controllable switch S12 is closed. When controlling the battery pack 101a1 to be reconnected to the circuit, the controller first controls both the first controllable switch S11 and the second controllable switch S12 to be open, and after a second preset time, controls the first controllable switch S11 to be closed.

[0095] The second preset time is longer than or equal to the dead time of the second controllable switch S12, so as to avoid a short circuit between the positive output terminal and the negative output terminal of the battery pack 101a1 caused by the simultaneous closing of the first controllable switch S11 and the second controllable switch S12. The second preset time is not particularly limited in this embodiment of the present application.

[0096] The principle of bypassing other battery packs is similar, and the details will not be described here again in this embodiment of the present application.

[0097] During practical application, when the first controllable switch S11 and the second controllable switch S12 use the same specification components, the first preset time and the second preset time can be the same.

[0098] The following describes a second implementation of the control of the bypass circuit.

[0099] Each second controller is configured to obtain a first parameter value of a corresponding battery pack, and send the first parameter value to the first controller 1001. The first parameter value is a voltage value or a SOC value.

[0100] The first controller determines a battery pack whose first parameter value is equal to or greater than a first preset parameter value as a bypass target battery pack when the battery cluster is charged, or determines a battery pack whose first parameter value is equal to or less than a second preset parameter value as a bypass target battery pack when the battery cluster is discharged. Then, the first controller 1001 sends a control command to each second controller. The control command is used to instruct the corresponding second controller to control a bypass circuit to bypass the bypass target battery pack. A detailed description is given below.

[0101] When the first parameter value is a voltage value, the first preset parameter value is a first preset voltage value, and the second preset parameter value is a second preset voltage value. When the battery cluster is charged, the electric quantities of the battery packs may be unbalanced, so that the time periods for fully charging the battery packs may be different, which is represented by the different voltage values ​​of the battery packs. The first controller sequentially determines the battery packs whose voltage values ​​are equal to or greater than the first preset voltage value as bypass target battery packs, and sends a control command to the second controller, so that the second controller controls the bypass circuit to sequentially bypass the bypass target battery packs until only one remaining battery pack is not bypassed. In this case, the electric quantities of the other bypassed battery packs are in a balanced state, and charging is completed.

[0102] In this case, only one remaining battery pack continues to be charged. When the first controller determines that the voltage value of the only remaining battery pack is equal to or greater than the first preset voltage value, it indicates that the charging of the battery cluster is completed in this case. The only remaining battery pack is no longer bypassed. Meanwhile, the second controller controls all bypassed battery packs to be reconnected to the battery cluster.

[0103] When the battery cluster is discharged, the electric quantity of the battery packs may be unbalanced, so the time period for fully discharging the battery packs may be different. Therefore, the voltages of the battery packs are different. The first controller sequentially determines the battery packs whose voltage value is equal to or lower than the second preset voltage value as bypass target battery packs, and sends a control command to the second controller, so that the second controller controls the bypass circuit to sequentially bypass the bypass target battery packs until only one remaining battery pack is not bypassed. In this case, the electric quantity of the other bypassed battery packs is balanced, and the discharge is completed.

[0104] In this case, only one remaining battery pack continues to be discharged. When the first controller determines that the voltage value of the only remaining battery pack is equal to or lower than the second preset voltage value, it indicates that the discharging of the battery cluster is completed in this case. The only remaining battery pack is no longer bypassed. Meanwhile, the second controller controls all bypassed battery packs to be reconnected to the battery cluster.

[0105] The implementation in which the controller controls the bypass circuit so that the battery packs are bypassed or reconnected in series to the battery cluster is the same as that described above, and the details will not be described again here.

[0106] In the above description, the first parameter value is used as an example that the voltage value. When the first parameter value is the SOC value, the first preset parameter value is the first preset SOC value, and the second preset parameter value is the second preset SOC value. The specific working process of the controller is the same as that described above, and the details are not described here again in this embodiment.

[0107] In summary, the energy storage system can keep the electric quantity of the battery packs in balance. After a fully charged or discharged battery pack is isolated, the other battery packs can be charged or discharged at the maximum current, thereby mitigating the impact on the current of the battery cluster. Furthermore, since the electric quantity of the battery packs is in balance, the maximum backup period is further realized. Furthermore, when a battery is determined to be abnormal, a bypass circuit may be controlled to bypass the battery pack found to be abnormal, in order to repair the malfunction and ensure that the remaining battery packs can continue to operate normally.

[0108] The controller of this embodiment of the present application may further control the working state of the power conversion circuit.The following provides a specific description with reference to the accompanying drawings.

[0109] FIG. 5 is a schematic diagram of another energy storage system according to an embodiment of the present application.

[0110] The power conversion circuit 20 of the energy storage system includes a DC / DC conversion circuit 201 and a DC / AC conversion circuit 202.

[0111] A first terminal of the DC / DC conversion circuit 201 is a first terminal of the power conversion circuit 20, a second terminal of the DC / DC conversion circuit 201 is connected to a first terminal of the DC / AC conversion circuit 202, and a second terminal of the DC / AC conversion circuit 202 is connected to the power conversion circuit 20. 20 This is the second terminal of the

[0112] The DC / DC conversion circuit 201 is configured to perform DC conversion on the DC supplied by the battery cluster 10 and then transmit the DC obtained by the DC conversion to the DC / AC conversion circuit 202, or to perform DC conversion on the DC supplied by the DC / AC conversion circuit 202 and then transmit the DC obtained by the DC conversion to the battery cluster 10 for charging the battery cluster 10.

[0113] The DC / AC conversion circuit 202 is configured to convert the DC provided by the DC / DC conversion circuit 201 into AC, or convert the AC acquired into DC, and then transmit the DC to the DC / DC conversion circuit 201. A second terminal of the DC / AC conversion circuit 202 can acquire AC from an AC power grid or a new energy power generation end.

[0114] In some embodiments, the DC / AC conversion circuit 202 is a bidirectional DC / AC converter, and may optionally be a neutral point clamped T-type three-level circuit, a neutral point clamped (NPC) circuit, an active neutral point clamped (ANPC) circuit, a flying capacitor multi-level circuit, etc. Since the port voltage of the battery cell varies with the energy storage capacity, the port output voltage of the battery cluster is a wide range of output voltage. Therefore, to match the variation range of the port voltage of the battery cluster, the DC / DC conversion circuit 201 and the DC / AC conversion circuit 202 generally support a wide range of input and output capabilities.

[0115] In some embodiments, online bypass or online connection may be performed when the battery pack is bypassed or connected, in which case the DC / DC conversion circuit 201 operates normally.

[0116] In some other embodiments, the controller 100 is further configured to control the DC / DC conversion circuit 201 to stop operating before bypassing or connecting the battery pack, and to resume operating after the battery pack is bypassed or connected. The DC / DC conversion circuit 201 stops operating, i.e., the DC / DC conversion circuit 201 is controlled to be powered off or the control signal is stopped being sent to the DC / DC conversion circuit 201.

[0117] The following specifically describes a method for controlling the DC / DC conversion circuit.

[0118] FIG. 6 is a schematic diagram of yet another energy storage system according to an embodiment of the present application.

[0119] The illustrated energy storage system further includes a soft start circuit 60. The positive port of the output end of the battery cluster 10 is connected to the positive port of the first terminal of the DC / DC conversion circuit 201 through the soft start circuit 60, or the negative port of the output end of the battery cluster 10 is connected to the negative port of the first terminal of the DC / DC conversion circuit 201 through the soft start circuit 60. Figure 6 shows an implementation in which the soft start circuit 60 is connected to the positive port of the first terminal of the DC / DC conversion circuit 201.

[0120] The soft-start circuit 60 specifically includes a first relay K1, a second relay K2, and a first resistor R1.

[0121] A first relay K1 is connected in series with a first resistor R1, which is then connected in parallel with a second relay K2.

[0122] The controller 100 is further configured to control the first relay and the second relay to be open before bypassing or connecting the battery pack, so that the DC / DC conversion circuit 201 stops operating.

[0123] Further, to protect the battery cluster, in some embodiments, the controller 100 is further configured to control the voltage at the first terminal of the DC / DC conversion circuit 201 to be equal to the output voltage of the battery cluster 10 and control the second relay K2 to be closed after completing the bypass or connection of the battery pack.

[0124] A bus capacitor (not shown) is usually disposed at the first terminal of the DC / DC conversion circuit 201. The controller 100 controls the voltage at the first terminal of the DC / DC conversion circuit 201 to be equal to the output voltage of the battery cluster 10, so that the voltage of the bus capacitor is equal to the output voltage of the battery cluster 10, and also controls the second relay K2 to be closed. In this case, the voltage of the bus capacitor is equal to the output voltage of the battery cluster 10. Unaffected This protects the battery cluster 10.

[0125] In some other embodiments, the controller 100 is further configured to initially control the first relay K1 to be closed and the second relay K2 to be open after completing the bypass or connection of the battery pack, and to control the first relay K1 to be open and the second relay K2 to be closed after a third preset time.

[0126] The role of setting the third preset time is to achieve potential equalization and to set the time for the battery cluster. influence After current limiting is performed using the first relay K1 and the first resistor R1 to reduce the charging and discharging between the first terminal of the DC / DC conversion circuit 201 and the output end of the battery cluster 10. The third preset time may be set based on the actual situation, which is not particularly limited in this embodiment of the present application.

[0127] The aforementioned soft-start circuit 60 may be integrated with the DC / DC conversion circuit 201, or the soft-start circuit 60 is arranged independently, which is not particularly limited in this embodiment of the present application.

[0128] In summary, based on the energy storage system provided in this embodiment of the present application, the electrical quantity of the battery pack can be in a balanced state. The DC / DC conversion circuit and the soft start circuit can prevent a relatively large current from flowing when the battery pack is bypassed or reconnected. ImpactIt may be further controlled to avoid the impact on the battery cluster caused by the above to protect the battery cluster.

[0129] Based on the energy storage system provided in the above embodiment, the present embodiment further provides an energy storage system control method applied to the energy storage system provided in the above embodiment. The method includes controlling a bypass circuit corresponding to each battery pack based on a first parameter value of each battery pack, so as to balance the electric quantity of the battery packs. The following provides a specific description with reference to the accompanying drawings.

[0130] The charge / discharge status of the battery pack is first determined.

[0131] FIG. 7 is a flow chart of a method for determining the charge / discharge state of a battery pack according to an embodiment of the present application.

[0132] The method includes the following steps:

[0133] S701: Start.

[0134] S702: Determine whether the battery pack has reached a fully charged state.

[0135] The battery pack reaches a fully charged state Execute S704 if The battery pack has not reached a fully charged state In this case, S703 is executed.

[0136] S703: Determine whether the battery pack has reached an end-of-discharge state.

[0137] If "no", continue to perform the decision again and perform S702 again after a certain period of delay, or if "yes", perform S705.

[0138] S704: A charging completion flag is set in the battery pack.

[0139] It indicates that the battery pack is in a fully charged state and may be bypassed.

[0140] S705: A discharge completion flag is set in the battery pack.

[0141] It indicates that the battery pack is in a discharged state and may be bypassed.

[0142] S706: Finished.

[0143] The following describes a method for controlling each battery pack to maintain electrical balance.

[0144] 8A and 8B are schematic diagrams of a method for controlling an energy storage system according to an embodiment of the present application.

[0145] S801: Start.

[0146] S802: Determine whether the battery pack is in a charging state.

[0147] If "yes", execute S803; if not, execute S804.

[0148] S803: Is the current battery pack fully charged?

[0149] If "yes", execute S805; if not, execute S806.

[0150] In some embodiments, it may be determined whether charging of the current battery pack is complete based on the charging completion flag for the battery pack in S704.

[0151] S804: Whether the current battery pack is completely discharged.

[0152] If "yes", execute S810; if not, execute S811.

[0153] In some embodiments, it may be determined whether discharging of the current battery pack is complete based on the discharge completion flag for the battery pack in S705.

[0154] S805: Determine whether the number of remaining non-bypassed battery packs is greater than one.

[0155] If "yes", execute S808; if not, execute S809.

[0156] S806: Determine whether detection of all battery packs has been completed.

[0157] If "yes", execute S815; if not, execute S807.

[0158] S807: Detect the next battery pack.

[0159] S808: Bypass the battery pack whose first parameter value is greater than or equal to the first preset parameter value.

[0160] That is, when the battery cluster is being charged, the battery packs whose first parameter value is greater than or equal to the first preset parameter value are sequentially bypassed until only one remaining battery pack is not bypassed.

[0161] In some embodiments, a second parameter value corresponding to the battery pack is first obtained, and then a first parameter value corresponding to the battery pack is determined based on the second parameter value corresponding to the battery pack, the second parameter value including a total capacity, a state of energy (SOE) value, and a state of health (SOH) value of the battery pack, and the first parameter value is a state of charge (SOC) value.

[0162] In some other embodiments, the first parameter value corresponding to the battery pack is obtained directly, and the first parameter value is a voltage value or a state of charge SOC value.

[0163] When the battery pack is bypassed, both the first controllable switch and the second controllable switch of the bypass circuit corresponding to the battery pack are controlled to open first, and after a first preset time, the second controllable switch is controlled to close. The first preset time is longer than or equal to the dead time of the first controllable switch, so as to avoid a short circuit between the positive output terminal and the negative output terminal of the battery pack caused by the simultaneous closing of the first controllable switch and the second controllable switch. The first preset time is not particularly limited in this embodiment of the present application.

[0164] S809: Control each bypass circuit so that the bypassed battery packs are reconnected to the battery cluster.

[0165] In this case, the electric quantity of the other bypassed battery packs is in a balanced state. If the first parameter value of only one remaining battery pack is equal to or greater than the first preset parameter value, it indicates that the charging of the battery cluster is completed in this case. The only remaining battery pack is no longer bypassed. Meanwhile, each bypass circuit is controlled to reconnect the bypassed battery pack to the battery cluster.

[0166] When the battery pack is controlled to be reconnected to the battery cluster, both the first controllable switch and the second controllable switch of the bypass circuit corresponding to the battery pack are initially controlled to be open, and then, after a second preset time value, the first controllable switch is controlled to be closed.

[0167] The second preset time is longer than or equal to the dead time of the second controllable switch, so as to avoid a short circuit between the positive output terminal and the negative output terminal of the battery pack caused by the simultaneous closing of the first controllable switch and the second controllable switch. The second preset time is not particularly limited in this embodiment of the present application.

[0168] S810: Determine whether the number of remaining non-bypassed battery packs is greater than one.

[0169] S811: Determine whether detection of all battery packs has been completed.

[0170] If "yes", execute S815; if not, execute S812.

[0171] S812: Detect the next battery pack.

[0172] S813: Bypass the battery packs whose first parameter value is less than or equal to the second preset parameter value.

[0173] That is, when the battery cluster is discharged, the battery packs whose first parameter value is less than or equal to the second preset parameter value are sequentially bypassed until only one remaining battery pack is not bypassed.

[0174] S814: Control each bypass circuit so that the bypassed battery packs are reconnected to the battery cluster.

[0175] In this case, the electric quantity of the other bypassed battery packs is in a balanced state. When the first parameter value of only one remaining battery pack is equal to or less than the second preset parameter value, it indicates that the discharge of the battery cluster is completed in this case. The only remaining battery pack is no longer bypassed. Meanwhile, each bypass circuit is controlled to reconnect the bypassed battery pack to the battery cluster.

[0176] S815: Finished.

[0177] The division and order of the above steps are merely for the purpose of simplifying the description, and do not constitute any limitation on the technical solutions of the present application. Those skilled in the art can make appropriate adjustments based on the actual situation.

[0178] In summary, based on the above control method provided in this embodiment of the present application, the electrical quantity of the battery packs can be in a balanced state. After a fully charged or discharged battery pack is separated, the other battery packs can be charged or discharged at a maximum current, thereby mitigating the impact on the current of the battery cluster. Furthermore, since the electrical quantity of the battery packs is in a balanced state, a maximum backup period is further realized. Furthermore, when it is determined that a battery is abnormal, a bypass circuit may be controlled to bypass the battery pack found to be abnormal, in order to repair the malfunction and ensure that the remaining battery packs can continue to operate normally.

[0179] The following describes a method for controlling a soft start circuit and a DC / DC conversion circuit in a power conversion circuit.

[0180] The positive port of the output end of the battery cluster is connected to the positive port of the first terminal of the DC / DC conversion circuit through the soft start circuit, or the negative port of the output end of the battery cluster is connected to the negative port of the first terminal of the DC / DC conversion circuit through the soft start circuit.

[0181] The soft start circuit specifically includes a first relay K1, a second relay K2, and a first resistor R1. The first relay K1 is connected in series with the first resistor R1, and then connected in parallel with the second relay K2.

[0182] For the specific implementation and working principle of the DC / DC conversion circuit, please refer to the description of the preceding embodiment, and the details will not be described again in this embodiment of the present application.

[0183] FIG. 9 is a schematic diagram of another control method for an energy storage system according to an embodiment of the present application.

[0184] S901: Before bypassing or connecting the battery pack to the battery pack, control a DC / DC conversion circuit connected to the output terminal of the battery cluster to stop operating, and at this time, a first terminal of the DC / DC conversion circuit is connected to the output terminal of the battery cluster.

[0185] S902: After completing the bypass or connection of the battery pack, control the voltage at the first terminal of the DC / DC conversion circuit to be equal to the output voltage of the battery cluster.

[0186] A bus capacitor is usually placed at the first terminal of the DC / DC conversion circuit. The voltage at the first terminal of the DC / DC conversion circuit is controlled to be equal to the output voltage of the battery cluster, so that the voltage of the bus capacitor is equal to the output voltage of the battery cluster, and then the second relay is controlled to be closed. In this case, the voltage of the bus capacitor is supplied to the battery cluster. Unaffected thereby protecting the battery cluster.

[0187] S902: The second relay K2 is controlled to be closed.

[0188] After the second relay K2 is closed, the DC / DC conversion circuit is controlled to start operating.

[0189] FIG. 10 is a schematic diagram of yet another method for controlling an energy storage system according to an embodiment of the present application.

[0190] S1001: Before bypassing or connecting the battery pack to the battery pack, a DC / DC conversion circuit connected to the output terminal of the battery cluster is controlled to stop operating, and both a first relay K1 and a second relay K2 are controlled to open, and at this time, a first terminal of the DC / DC conversion circuit is connected to the output terminal of the battery cluster.

[0191] S1002: Control the first relay K1 to be closed and the second relay K2 to be opened, and after a third preset time, control the first relay K1 to be opened and the second relay K2 to be closed.

[0192] The role of setting the third preset time is to achieve potential equalization and to set the time for the battery cluster. influence After current limiting is performed using the first relay and the first resistor to reduce the charging and discharging between the first terminal of the DC / DC conversion circuit and the output end of the battery cluster 10. The third preset time may be set based on the actual situation, which is not particularly limited in this embodiment of the present application.

[0193] In summary, based on the control method provided in this embodiment of the present application, the electrical quantity of the battery pack can be in a balanced state. The DC / DC conversion circuit and the soft start circuit can prevent a relatively large current from flowing when the battery pack is bypassed or reconnected. Impact It may be further controlled to avoid the impact on the battery cluster caused by the above to protect the battery cluster.

[0194] Based on the energy storage system provided in the foregoing embodiment, an embodiment of the present application further provides a solar power generation system. The following is given in detail with reference to the accompanying drawings.

[0195] FIG. 11 is a schematic diagram of a solar power generation system according to an embodiment of the present application.

[0196] The illustrated solar power system includes an energy storage system and a solar power end 301 .

[0197] The energy storage system includes a battery cluster 10, a power conversion circuit 20, and a controller 100.

[0198] A battery cluster is connected to a power conversion circuit to form an energy storage branch, and the energy storage system includes at least one energy storage branch.

[0199] For the specific implementation and working principle of the energy storage system, please refer to the relevant descriptions of the preceding embodiments, and the details will not be described again in this embodiment of the present application.

[0200] The solar power end 301 specifically includes a solar power generation module and a power conversion system, a detailed description of which is given below.

[0201] Photovoltaic modules are configured to generate direct current by using light energy.

[0202] The power conversion system is configured to convert direct current generated by the solar photovoltaic module into alternating current.

[0203] In some embodiments, the power conversion system includes a DC combiner box and a centralized inverter. The centralized inverter includes an inverter circuit configured to convert a DC input by at least one current combiner box to an AC input. Each centralized inverter has a relatively high power.

[0204] In some other embodiments, the power conversion system includes a string inverter and an AC combiner box. The DC side of the string inverter is connected to one or more photovoltaic modules. In practical applications, the DC side of the string inverter is generally connected to multiple photovoltaic modules.

[0205] The power of string inverters is smaller than that of centralized inverters. Therefore, string inverters mostly use outdoor modular and contain two-stage power conversion circuits. The first stage is a DC / DC conversion circuit, which is generally a boost circuit, and the second stage is an inverter circuit.

[0206] In some other embodiments, the power conversion system includes an inverter and a maximum power point tracking (MPPT) boost combiner box, the MPPT boost combiner box being a boost converter, an input of the MPPT boost combiner box being connected to the photovoltaic module, and an output of the MPPT boost combiner box being connected to the input of the inverter.

[0207] The output of the photovoltaic power generation end is configured to be connected to an AC power grid and to transmit the generated AC to the AC power grid or to charge the battery cluster 10 through the power conversion circuit 20 .

[0208] FIG. 12 is a schematic diagram of another solar power generation system according to an embodiment of the present application.

[0209] The illustrated solar power generation system includes an energy storage system and a solar power generation module 80 .

[0210] A battery cluster is connected to a power conversion circuit to form an energy storage branch, and the energy storage system includes at least one energy storage branch. Each battery cluster 10 is connected to at least one photovoltaic power generation module 80. In practical application, each battery cluster 10 is generally connected to multiple photovoltaic power generation modules accordingly.

[0211] The photovoltaic module 80 is configured to generate direct current by using light energy to charge the battery cluster 10 .

[0212] Each battery pack in the battery cluster of the photovoltaic power generation system provided in this embodiment of the present application is connected to one bypass circuit accordingly, and the controller controls each bypass circuit according to the first parameter value of each battery pack, so that the battery pack can be bypassed from the battery cluster. When the battery cluster is charged, the bypassed battery pack stops charging first. As the battery pack is gradually bypassed, the electric amount of the battery pack in the battery cluster is synchronized. When the battery cluster is discharged, the bypassed battery pack stops discharging first. As the battery pack is gradually bypassed, the electric amount of the battery pack in the battery cluster is also synchronized. However, after the battery pack is bypassed, the remaining battery pack can still be charged or discharged with the maximum current. Therefore, the current of the battery cluster can remain unchanged. In short, the energy storage system can balance the electric amount of the battery pack, thereby reducing the impact on the current of the battery cluster and further reducing the waste of the electric amount. Furthermore, since the electric amount of the battery pack is in a balanced state, the maximum backup period is further realized.

[0213] In this application, it should be understood that "at least one (item)" refers to one or more, and "multiple" refers to two or more. The term "and / or" is used to indicate an association relationship between related objects, and indicates that three relationships may exist. For example, "A and / or B" can indicate three cases: only A is present, only B is present, and both A and B are present, where A and B may be singular or plural. The character " / " generally indicates a "logical or" relationship between related objects. "At least one of the following items (parts)" or similar expressions refers to any combination of items, including any combination of a singular item (part) or multiple items (parts). For example, at least one of a, b, and c can indicate a, b, c, a and b, a and c, b and c, a, b, and c, where a, b, and c may be singular or plural.

[0214] The above embodiments are not intended to limit the present application, but are merely intended to describe the technical solutions of the present application. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art can easily understand the technical solutions of the embodiments of the present application. Suitable for It should be understood that the technical solutions described in the above embodiments may still be modified or some of the technical features may be equivalently substituted without departing from the scope of the present invention.

Claims

1. 1. An energy storage system comprising a battery cluster, a power conversion circuit, and a controller, comprising: an output terminal of the battery cluster is connected to a first terminal of the power conversion circuit, and a second terminal of the power conversion circuit is connected to the output terminal of the energy storage system; Each battery cluster has at least two energy storage modules connected in series, each energy storage module having a bypass circuit and a battery pack, each battery pack including a plurality of batteries; the controller is configured to control the bypass circuit based on a first parameter value of each battery pack such that the electrical quantities of the battery packs are in balance; The controller includes a first controller and at least two second controllers; the second controller is connected to the battery pack in a one-to-one correspondence; each of the second controllers is configured to obtain a second parameter value of a corresponding battery pack and transmit the second parameter value to the first controller; the first controller is configured to determine first parameter values ​​of all the battery packs based on second parameter values ​​of all the battery packs, determine the battery packs whose first parameter values ​​are equal to or greater than a first preset parameter value as bypass target battery packs when the battery cluster is being charged, and determine the battery packs whose first parameter values ​​are equal to or less than a second preset parameter value as bypass target battery packs when the battery cluster is being discharged, and send a control command to a corresponding one of the second controllers associated with the bypass target battery packs, the control command instructing the corresponding one of the second controllers to control the bypass circuit to bypass the bypass target battery packs. Energy storage systems.

2. the bypass circuit includes a first controllable switch and a second controllable switch; a positive output terminal of the battery pack is connected to a first terminal of the first controllable switch, a second terminal of the first controllable switch is connected to a first terminal of the second controllable switch and to a positive output terminal of the energy storage module, a second terminal of the second controllable switch is connected to a negative output terminal of the energy storage module, and a negative output terminal of the battery pack is connected to the negative output terminal of the energy storage module; 10. The energy storage system of claim 1 .

3. the controller is specifically configured to initially control both the first controllable switch and the second controllable switch to be open, and after a first preset time, control the second controllable switch to be closed to bypass the battery pack.

3. The energy storage system of claim 2.

4. The power conversion circuit includes a DC / DC conversion circuit, The DC / DC conversion circuit is configured to perform DC conversion on an input DC.

4. An energy storage system according to any one of claims 1 to 3.

5. The power conversion circuit further includes a DC / AC conversion circuit, a first terminal of the DC / DC conversion circuit is the first terminal of the power conversion circuit, a second terminal of the DC / DC conversion circuit is connected to the first terminal of the DC / AC conversion circuit, and a second terminal of the DC / AC conversion circuit is the second terminal of the power conversion circuit; the DC / AC conversion circuit is configured to convert the DC provided by the DC / DC conversion circuit into an AC current, or convert the AC current obtained through the second terminal of the DC / AC conversion circuit into a DC current, and then transmit the DC current obtained through the conversion to the DC / DC conversion circuit; 5. The energy storage system of claim 4.

6. The energy storage system further includes a soft start circuit, and the positive port of the output end of the battery cluster is connected to the positive port of the first terminal of the DC / DC conversion circuit through the soft start circuit, or the negative port of the output end of the battery cluster is connected to the negative port of the first terminal of the DC / DC conversion circuit through the soft start circuit, and the soft start circuit includes a first relay, a second relay, and a first resistor; the first relay is connected in series to the first resistor and then in parallel to the second relay; The controller is further configured to control the first relay and the second relay to be open prior to bypassing or connecting to the battery pack.

6. An energy storage system according to claim 4 or 5.

7. The controller is further configured to control a voltage at the first terminal of the DC / DC conversion circuit to be equal to an output voltage of the battery cluster after completing the bypass or connection of the battery pack, and to control the second relay to be closed.

7. The energy storage system of claim 6.

8. The controller is further configured to control the first relay to be closed and the second relay to be open after completing the bypass or connection of the battery pack, and to control the first relay to be open and the second relay to be closed after a third preset time.

7. The energy storage system of claim 6.

9. the second parameter value includes a total capacity of the battery pack, a state of energy (SOE) value, and a state of health (SOH) value, and the first parameter value is a state of charge (SOC) value.

9. An energy storage system according to any one of claims 1 to 8.

10. 1. A method of controlling an energy storage system, wherein each battery cluster in the energy storage system has at least two energy storage modules connected in series, each energy storage module having a bypass circuit and a battery pack, each battery pack including a plurality of batteries, the method comprising: controlling each bypass circuit based on a first parameter value of each battery pack such that the electrical quantities of the battery packs are in a balanced state; Controlling each of the bypass circuits includes: acquiring a second parameter value of the corresponding battery pack by each of the second controllers connected to the battery packs in a one-to-one correspondence, and sending the second parameter value to a first controller which is a higher-level controller of the second controllers; determining, by the first controller, first parameter values ​​of all the battery packs in the battery cluster based on second parameter values ​​of the all the battery packs in the battery cluster, determining, when the battery cluster is being charged, a battery pack in the battery cluster whose first parameter value is equal to or greater than a first preset parameter value as a bypass target battery pack, and when the battery cluster is being discharged, determining, when the battery cluster is being discharged, a battery pack in the battery cluster whose first parameter value is equal to or less than a second preset parameter value as a bypass target battery pack, and sending a control command to a corresponding one of the second controllers associated with the bypass target battery pack; and controlling, by the corresponding second controller, a corresponding bypass circuit to bypass the bypass target battery pack according to the control command. method.

11. The method comprises: Prior to bypassing or connecting to the battery pack, control a DC / DC conversion circuit connected to an output end of the battery cluster to stop operating, and a first terminal of the DC / DC conversion circuit is connected to the output end of the battery cluster; and After completing the bypass or connection of the battery pack, controlling the voltage at the first terminal of the DC / DC conversion circuit to be equal to the output voltage of the battery cluster, and controlling the DC / DC conversion circuit to start operating. Further comprising 11. The method of controlling an energy storage system according to claim 10.

12. The battery pack according to claim 11, wherein the second parameter value includes a total capacity of the battery pack, a state of energy (SOE) value, and a state of health (SOH) value, and the first parameter value is a state of charge (SOC) value.

12. A method for controlling an energy storage system according to claim 10 or 11.

13. The battery pack includes a second controller, a bypass circuit, and a battery pack, each battery pack including a plurality of batteries. the second controller is connected to the battery pack; the second controller is configured to obtain a second parameter value of the battery pack, and send the second parameter value to a first controller that is a higher-level controller of the second controller, so that the first controller can determine a first parameter value of the battery pack based on the second parameter value; the second controller is further configured to receive a control command sent by the first controller based on the first parameter value, and to control the bypass circuit to bypass the battery pack according to the control command; the second controller is specifically configured to control the bypass circuit to bypass the battery pack when the battery pack is charged and the first parameter value of the battery pack is equal to or greater than a first preset parameter value, or to control the bypass circuit to bypass the battery pack when the battery pack is discharged and the first parameter value of the battery pack is equal to or less than a second preset parameter value. Energy storage module.

Images