Energy storage system and its control method

Abstract

An energy storage device capable of balancing between battery modules and a method for controlling the same are disclosed. An energy storage device according to one embodiment may include: a battery unit comprising one or more battery modules; a battery management unit comprising one or more battery management systems connected to each of the one or more battery modules; a power conversion unit comprising one or more power conversion modules for charging or discharging the one or more battery modules; a switch unit comprising one or more switches for controlling the connection of power wiring between the one or more battery modules and the one or more power conversion modules; and a control unit connected to at least one of the one or more battery management systems, one or more power conversion modules, and one or more switches, and controlling at least one of the one or more power conversion modules and one or more switches based on state information of the battery modules received from at least one of the one or more battery management systems to control at least one of the voltage and charge state between the one or more battery modules to be uniform within a predetermined range.

Description

Technology Field

[0001] The present invention relates to a technology for energy storage devices, in particular to an energy storage device capable of balancing between battery modules and a method for controlling the same. Background Technology

[0002] Energy storage systems are systems that store electrical energy and supply it as needed, and are used in combination with renewable energy sources such as solar and wind power, or to stabilize the power grid. These devices typically consist of battery modules, each of which stores and releases power independently. However, imbalances in the State of Charge (SOC) and voltage between battery modules can occur within energy storage systems. In particular, when using recycled battery modules (e.g., batteries recycled from electric vehicles), the imbalance problem can be exacerbated due to varying performance and condition of the modules. Such imbalances can lead to reduced system efficiency, shortened lifespan, and even safety issues.

[0003] To solve such problems, a balancing structure and control method that uniformly adjusts the voltage and charge state between battery modules is essential. Balancing can be achieved by transferring energy from a high-voltage battery to a low-voltage battery, or through a control algorithm that detects and adjusts an imbalanced state. The problem to be solved

[0004] The purpose is to provide an energy storage device capable of balancing between battery modules and a method for controlling the same. means of solving the problem

[0005] According to one aspect, the energy storage device may include: a battery unit comprising one or more battery modules; a battery management unit comprising one or more battery management systems connected to each of the one or more battery modules; a power conversion unit comprising one or more power conversion modules for charging or discharging the one or more battery modules; a switch unit comprising one or more switches for controlling the connection of power wiring between the one or more battery modules and the one or more power conversion modules; and a control unit connected to at least one of the one or more battery management systems, one or more power conversion modules, and one or more switches, and controlling at least one of the one or more power conversion modules and one or more switches based on state information of the battery modules received from at least one of the one or more battery management systems to control at least one of the voltage and charge state between the one or more battery modules to be uniform within a predetermined range. Effects of the invention

[0006] The present invention can provide a method to improve the efficiency and stability of an energy storage device by effectively resolving the state of charge (SOC) and voltage imbalance between battery modules. In particular, through precise power adjustment utilizing a balancing DC-DC converter and a control unit, battery life can be extended and performance degradation can be minimized even in reused battery modules. Brief explanation of the drawing

[0007] Figure 1 is a diagram of a conventional energy storage device. FIG. 2 is a configuration diagram of an energy storage device according to one embodiment. FIGS. 3 to 10 are illustrative diagrams for explaining the configuration and operation of an energy storage device according to one embodiment. Specific details for implementing the invention

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings. In describing the present invention, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions may unnecessarily obscure the essence of the present invention. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0009] Hereinafter, embodiments of an energy storage device and method will be described in detail with reference to the drawings.

[0010] Figure 1 is a diagram of a conventional energy storage device.

[0011] Referring to FIG. 1, the energy storage device may be composed of a battery module, a battery management system, and a power conversion module. The battery section, composed of one or more battery modules, is responsible for energy storage of the system. The battery section may be composed of a rack in which one or more battery modules are connected in series, and each rack may or may not include a DC-DC converter (DCDC) for independent operation.

[0012] When a DC-DC converter is included, individual racks can operate independently, which is advantageous in terms of maintenance; however, when a DC-DC converter is absent, the entire system operates integrally, offering a cost advantage. In the event of a battery module failure, if a DC-DC converter is present, only the affected rack becomes inoperable while the remaining racks continue to operate normally; whereas, without a DC-DC converter, there is a limitation in that the entire system becomes inoperable.

[0013] When energy storage devices are used for a long period (several years), voltage deviations between modules may occur. This is a major cause of reduced capacity in energy storage systems (ESS), and a separate module balancing operation is required to resolve this.

[0014] The energy storage device includes a battery management unit comprising a battery management system (BMS) capable of monitoring and managing the status of each battery module. The power conversion unit is responsible for charging or discharging the battery modules, and this component may include a DC-AC inverter and a DC-DC converter.

[0015] A Battery Management System (BMS) plays a role in maintaining system stability and lifespan by monitoring and managing the battery's condition in real time. The BMS continuously monitors the voltage, temperature, State of Charge (SOC), and the battery's current performance and State of Health (SOH) of each battery module, and can detect abnormalities and perform protective actions. In addition, the BMS can operate as a safety device to prevent battery overcharging, over-discharging, and overheating to ensure efficient battery usage and extend its lifespan.

[0016] A DC-AC converter (inverter) is a device that converts direct current (DC) power into alternating current (AC) power. This device serves to supply DC power generated from solar panels or batteries to a standard power grid or load devices that use AC. The DC-AC converter (inverter) is a core device that manages the bidirectional power flow of energy storage devices and can support both charging and discharging. During charging, it converts an external power grid or AC power into DC to supply power to the battery, and during discharging, it converts the battery's DC power into AC power to release it to the power grid or external loads.

[0017] A DC-DC converter is a device that converts direct current power into direct current at a different voltage level. DC-DC converters can adjust voltage differences between battery modules or control power flow in individual racks. By enabling battery modules to operate independently, DC-DC converters can improve maintenance and operational efficiency.

[0018] FIG. 2 is a configuration diagram of an energy storage device according to one embodiment.

[0019] According to one embodiment, an energy storage device (100) may include a battery unit (110) including one or more battery modules, a battery management unit (120) including one or more battery management systems connected to each of the one or more battery modules, a power conversion unit (130) including one or more power conversion modules for charging or discharging one or more battery modules, a switch unit (140) including one or more switches for controlling the connection of power wiring between one or more battery modules and one or more power conversion modules, and a control unit (150).

[0020] According to one embodiment, the control unit (150) is connected to at least one of one or more battery management systems, one or more power conversion modules, and one or more switches, and can control at least one of one or more power conversion modules and one or more switches based on state information of a battery module received from at least one of one or more battery management systems to control at least one of the voltage and charge state between one or more battery modules to be uniform within a predetermined range.

[0021] The control unit (150) is a core control device of the energy storage system and is connected to at least one of a battery management system (BMS), a power conversion module, and a switch. The control unit (150) can operate to control the power conversion module and the switch based on the status information of each battery module received from the battery management system, so as to maintain key parameters such as voltage and state of charge (SOC) between battery modules uniformly within a predetermined range.

[0022] Between battery modules, an imbalance in voltage and state of charge may occur due to differences in usage during the charging and discharging process, an imbalance in the state of charge (SOC), and battery performance degradation due to long-term use. Such an imbalance may lead to a decrease in the overall efficiency of the energy storage system, a shortened battery life, and safety issues. Accordingly, the control unit (150) performs a balancing operation and can maintain the stability and performance of the system by adjusting the state between each module equally.

[0023] For example, the control unit (150) can evaluate the state of each battery based on the average value of the voltage or state of charge (SOC) of one or more battery modules included in the same rack. The control unit (150) can compare this average value with the voltage or state of charge of individual battery modules and determine that the battery is in an unbalanced state if a specific battery module is outside a predetermined allowable range. In this way, the control unit (150) can detect the difference in state between battery modules in real time and perform necessary measures based on this.

[0024] According to one embodiment, the power conversion unit (130) may include a first power conversion module connected in series with one or more battery modules and a second power conversion module connected in parallel with one or more battery modules. For example, the first power conversion module and the second power conversion module may be connected in parallel.

[0025] Referring to FIG. 3, the first power conversion module is connected in series with the battery module and can primarily support the charging and discharging processes of the energy storage system. This module may be configured as a DC-AC converter (inverter), and may also be configured as a combination of a DC-AC converter and a DC-DC converter as needed. Through this, the DC power of the battery module can be converted into AC power suitable for an external load or power grid, or external power can be stored in the battery.

[0026] The second power conversion module is a balancing DC-DC converter connected in parallel with the battery module and can perform balancing to maintain the balance of voltage or state of charge (SOC) between the battery modules. This module detects the imbalance in the battery system and adjusts the state of individual batteries, thereby increasing the efficiency and extending the lifespan of the energy storage system.

[0027] In one embodiment, a first power conversion module and a second power conversion module may be connected in parallel. For example, the first power conversion module is composed of a DC-AC converter (inverter) and performs the main power conversion operation (charging and discharging) of the energy storage system. The second power conversion module connected in parallel performs the function of balancing and serves to maintain the balance of voltage and state of charge (SOC) between battery modules.

[0028] For example, the second power conversion module can be connected in parallel with the source side (battery module side) of the DC-AC converter. In this configuration, the second power conversion module adjusts the state of the battery module, manages energy flow between specific modules, and performs balancing.

[0029] As another example, the second power conversion module can be connected in parallel between the DC-AC converter and the DC-DC converter. In this case, the second power conversion module interacts with the energy path delivered through the DC-DC converter and can more precisely adjust the voltage and charge state between the battery modules. This parallel connection structure enables independent and harmonious operation of each module within the power conversion unit (130), thereby increasing the stability and efficiency of the entire system.

[0030] According to one embodiment, the switch unit (140) may include a first switch (1) that controls the connection of a power line connected to at least one of the positive and negative poles of each of the one or more battery modules in the power line between the second power conversion module and one or more battery modules, a second switch (2) that controls the connection of a power line connected to the first power conversion module and the second power conversion module with the positive or negative pole of each of the one or more battery modules, and a third switch (3) located on the load-side power line of the second switch and controlling a bypass by connecting the positive and negative poles of each of the one or more battery modules.

[0031] The first switch (1) is a switch that controls the connection between the battery module and the second power conversion module (Balancing DCDC), and operates to selectively connect a specific battery module that requires balancing to the second power conversion module. This allows the second power conversion module to be used to balance the module when an imbalance occurs in voltage or state of charge (SOC) between battery modules.

[0032] The second switch (2) controls the power wiring connected between the positive or negative electrode of the battery module and the first power conversion module and the second power conversion module, and serves to cut off the power to the battery module. When the second switch is in the open state, the power flow to the battery module is interrupted and the module is excluded from the charging or discharging path. This can be used to safely disconnect the module if an abnormal condition of a specific battery module is detected or maintenance is required during system operation.

[0033] The third switch (3) is located on the load-side power wiring of the second switch (2) and has the function of bypassing the module by directly connecting the positive and negative terminals of the battery module. That is, when the second switch is opened and the third switch is closed, the battery module is structured so that its positive and negative terminals are directly connected and it is bypassed from the power flow path. This provides a function to completely exclude the module from the entire system in the event of a problem and to continue operation using only the remaining modules.

[0034] According to one embodiment, the control unit (150) can determine each of the one or more battery modules based on the status information of the battery module received from one or more battery management systems to be in a normal mode, a separation mode in which the battery module is separated from another battery module when it is determined that an abnormality has occurred according to a predetermined standard, and a balancing mode in which at least one of the voltage and charge state between the battery modules is out of a predetermined range.

[0035] For example, the control unit (150), based on the status information of each battery module received from the battery management system (BMS), determines that the battery module is operating normally within a predetermined standard and determines the module to be in normal mode. In normal mode, the battery module performs normal charging and discharging operations together with other components of the system, and power flow and state management are maintained stably. In this state, no separate additional control or adjustment is required, and the system operates efficiently and stably.

[0036] According to one embodiment, the control unit (150) can control the first switch to open, the second switch to close, and the third switch to open for a battery module determined to be in normal mode. Referring to FIG. 4(a), in normal mode, the control unit (150) controls the first switch to open, the second switch to close, and the third switch to open. This setting allows the battery module to participate in normal charging and discharging operations together with other modules, and maintains a smooth power flow within the system.

[0037] If the status information of a battery module deviates from a predetermined standard or if an abnormal state is detected, the control unit (150) may determine the battery module to be in a disconnection mode. In this mode, the problematic battery module is electrically disconnected from other battery modules of the system. This prevents power imbalance, overcharging, over-discharging, or safety accidents that may occur due to the abnormal battery module. In the disconnection mode, the problematic battery module may be physically excluded from system operation by opening a switch or activating a bypass.

[0038] According to one embodiment, the control unit (150) can control the battery module determined to be in a separation mode by opening the first switch, opening the second switch, and closing the third switch. Referring to FIG. 4(b), in the separation mode, the control unit (150) controls the first switch to open, the second switch to open, and the third switch to closed, thereby bypassing the problematic battery module and excluding it from system operation, thereby maintaining the safety and stability of the remaining modules and the entire system.

[0039] According to one example, the control unit (150) may determine the module to be in a balancing mode when the voltage or state of charge (SOC) between the battery modules deviates from a predetermined allowable range. In the balancing mode, the control unit controls the second power conversion module and the switch to perform balancing operations to resolve the imbalance between the battery modules. In this process, the control unit (150) can optimize the efficiency and lifespan of the system by raising or lowering the state of charge of a specific module to make it uniform with other modules.

[0040] According to one embodiment, the control unit (150) can control the first switch to a closed state, the second switch to a closed state, and the third switch to an open state. Referring to FIG. 4(c), the control unit (150) can activate the second power conversion module by controlling the first switch to a closed state, the second switch to a closed state, and the third switch to an open state, thereby adjusting the state of a specific battery module and matching it uniformly with other modules. This resolves imbalances between battery modules and maintains the efficiency and lifespan of the system.

[0041] According to one embodiment, the control unit (150) controls the second power conversion module to supply power to the battery module determined in the balancing mode when charging is required for the battery module determined in the balancing mode, and controls the second power conversion module to transfer power from the battery module determined in the balancing mode to the outside when discharging is required for the battery module determined in the balancing mode.

[0042] The control unit (150) can perform control operations on a battery module determined to be in a balancing mode to resolve voltage or state of charge (SOC) imbalance between battery modules. Specifically, when charging is required for a battery module determined to be in a balancing mode, the control unit (150) can control the activation of a second power conversion module to supply power to the battery module. In this process, the second power conversion module can charge the battery module set to the balancing mode by switching power stored in another battery module or by using power supplied from an external power source. Through this, the state of a battery module with a low state of charge can be matched uniformly with that of other modules.

[0043] On the other hand, if discharge is required for a battery module set to balancing mode, the control unit (150) can activate a second power conversion module to control the transfer of excess power accumulated in the battery module to the outside. At this time, the discharged power can be transferred to another battery module or released to an external load of the system for use. Through this discharge process, the energy of the battery module with a high charge state is adjusted to balance it with other modules.

[0044] According to one example, the second power conversion module may be a bidirectional DC-DC converter. Both the first side and the second side of the second power conversion module (130-2) may be connected to the positive and negative terminals of the battery module. Subsequently, by controlling a switch for the battery module requiring balancing, one or more battery modules may be set as the input side and one or more battery modules as the output side. For example, the control unit (140) may control the switching unit (140) to control one or more battery modules to be connected to the first side and to control one or more battery modules to be connected to the second side.

[0045] For example, one or more battery modules can be divided into two groups. In this case, the first side of the second power conversion module is connected to the battery module included in the first group, and the second side can be connected to the battery module included in the second group.

[0046] Referring to FIG. 5, the battery module can be divided into a first group (a) and a second group (b). At this time, the first side of the second power conversion module (130-2) is connected to the first group (a), and the second side of the second power conversion module (130-2) can be connected to the second group (b).

[0047] The control unit (150) can control the switch module, DC-DC converter, DC-AC converter, and Balancing DC-DC converter connected to the BMS via communication for stable and efficient operation of the energy storage device. Each switch is responsible for a specific role, and the control unit (150) can dynamically control the switches according to the system's operating mode (normal mode, disconnected mode, balancing mode).

[0048] For example, in normal mode, all battery modules are integrated into the system and participate in charging, discharging, and normal power flow. In this case, switch 2 is set to the closed state to connect the battery modules to the system, and switch 3 is set to the open state to prevent bypassing of the battery modules.

[0049] The disconnection mode is used when a specific battery module malfunctions or requires maintenance. The control unit (150) can disconnect the module from the system by setting switch 2 of the battery module to the open state, and simultaneously bypass the battery module by setting switch 3 to the closed state.

[0050] This is performed to resolve imbalances in voltage and state of charge (SOC) between battery modules in balancing mode. In this state, the control unit (150) keeps switch 2 of the corresponding battery module in a closed state so that the module is connected to the system, and keeps switch 3 in an open state to prevent bypass. Additionally, switches 1, 4, and 5 required for balancing can be set to a closed state to enable power flow between the Balancing DC-DC converter and the corresponding battery module. Specifically, the control unit (150) controls switches 1 and 5 for one or more battery modules included in the first group (a) and controls switches 4 and 5 for one or more battery modules included in the second group (b) to transfer power from the first group (a) to the second group (b), or perform the opposite operation to balance the battery modules. If two or more modules are included in the balancing operation, the control unit (150) can close two switches No. 5 to activate each balancing path. At this time, the battery module in disconnect mode is not included in the balancing operation.

[0051] For example, the second power conversion module can be configured as shown in FIG. 6. The second power conversion module may be a Balancing Converter, and the second power conversion module is a power conversion device that optimizes the efficiency and lifespan of the battery system by adjusting the imbalance of voltage and state of charge (SOC) between battery modules. The second power conversion module is designed to transfer power bidirectionally between battery modules to resolve the imbalance of voltage and SOC. Through this, it adjusts performance deviations between battery modules that may occur in an energy storage system (ESS) or an electric vehicle battery management system (BMS), and supports stable system operation.

[0052] Referring to FIG. 6, the second power conversion module (130-2) is a device for resolving voltage and state of charge (SOC) imbalances between battery modules and may be composed of a switching element consisting of a diode and a MOSFET, an inductor, and a capacitor. Each component may be used to transfer energy bidirectionally between battery modules.

[0053] Switching elements (a) through (d) are formed by connecting a diode and a MOSFET in parallel, controlling the flow of current and transferring power through switching operations. (a) and (c) form a path for extracting or transferring power from battery module 1, while (b) and (d) serve to extract or transfer power from battery module 2. The inductor (e) stores and releases current in the form of a magnetic field to smoothly transfer energy. The inductor is a key component for storing and transferring energy between battery module 1 and battery module 2, and can adjust voltage and current in combination with switching operations. The capacitor (f) can reduce voltage ripple that may occur on the battery module side and flatten the voltage, thereby increasing the stability of the power transfer process.

[0054] In the power transfer operation from battery module 1 to battery module 2, (c) a MOSFET can extract current from battery module 1 through a switching operation and store it in an inductor (e). At this time, the diode in (a) can induce the current toward the inductor and block reverse current. The energy stored in the inductor is released to battery module 2 as (d) the MOSFET switches, and the diode in (b) can control the current to flow only to battery module 2.

[0055] Conversely, when power is transferred from battery module 2 to battery module 1, (d) the MOSFET is switched so that the current from battery module 2 is stored in the inductor (e). During this process, the diode in (b) induces current into the inductor and blocks reverse current. The stored energy is transferred to battery module 1 as (c) the MOSFET is switched, and the diode in (a) can control the current to flow to battery module 1.

[0056] According to one embodiment, the energy storage device (100) further includes one or more photovoltaic (PV) panels (160), and one or more photovoltaic panels are each connected in parallel with one or more battery modules to supply power to the battery modules.

[0057] Solar panels are photovoltaic modules that convert sunlight into electrical energy, serving to transfer the generated power to battery modules or supply it directly to system loads. These panels can be configured in series or parallel depending on system requirements. Series connections generate high voltage, while parallel connections provide high current, supporting flexible design. Furthermore, solar panels can be combined with a PV Optimizer to maximize efficiency. The PV Optimizer optimizes the power of each panel through Maximum Power Point Tracking (MPPT), and configuring them in series or parallel can further enhance the performance of the entire system.

[0058] Referring to FIG. 7, a PV DC-DC converter (130-3) may be used to control power transfer between a solar panel and a battery module. The PV DC-DC converter converts power generated from the solar panel into a voltage and current suitable for the battery module. This converter may be composed of a buck, boost, or buck-boost converter. A buck converter lowers the voltage when the voltage of the solar panel is higher than the battery charging voltage, while a boost converter raises the voltage when the voltage of the solar panel is lower than the battery charging voltage. A buck-boost converter is a flexible design capable of handling all situations where the voltage is higher or lower than the battery charging voltage, and can operate stably under various conditions.

[0059] PV DC-DC converters can maximize the output power of solar panels through MPPT functionality. MPPT optimizes the output characteristics of each panel, whether connected in series or parallel, and effectively manages power output that fluctuates due to external conditions such as weather. The combination of PV DC-DC converters and solar panels, when linked with battery modules, can support stable and efficient power supply and storage.

[0060] According to one example, the switch unit (140) may include a second switch (2) that controls the connection of power wiring connected to the positive or negative electrode of each of one or more battery modules and the first power conversion module (130-1) and the first power conversion module (130-3); a third switch (3) located on the load-side power wiring of the second switch and controlling a bypass by connecting the positive and negative electrodes of each of one or more battery modules; and a fourth switch (4) that controls the connection of one or more solar panels and one or more battery modules with the first power conversion module (130-1).

[0061] For example, the second switch (2) may be provided on the positive (2) wiring of the battery module or on the negative (a) wiring as shown in FIG. 7. Additionally, the fourth switch (4) may be provided on the positive (4) wiring of the battery module or on the negative (b) wiring.

[0062] According to one embodiment, the switch unit (140) further includes a fourth switch that controls the connection of one or more solar panels and one or more battery modules with the first power conversion module, and the first switch may be further connected to one or more solar panels.

[0063] Referring to FIG. 8, the switch unit (140) includes various switches to control the power flow of the energy storage device and controls the connection between one or more solar panels, battery modules, a first power conversion module, and a second power conversion module. The switch unit includes a fourth switch and a first switch, and the power flow of the solar panels and battery modules is controlled according to their respective operations.

[0064] The fourth switch controls the connection between the solar panel and battery module and the first power conversion module. When the fourth switch is opened, the power generated by the solar panel and the power stored in the battery module are not transferred to the first power conversion module, thereby blocking the power flow. This is used to protect the power conversion module during maintenance or abnormal conditions and to ensure the safety of the system.

[0065] The first switch controls the connection between the solar panel and battery module and the second power conversion module. When the first switch is opened, power from the solar panel and battery module is not transferred to the second power conversion module, and thus the power flow is blocked.

[0066] Referring to FIG. 8, the second switch (2) may be provided on the positive (2) wiring of the battery module or on the negative (a) wiring. Additionally, the fourth switch (4) may be provided on the positive (4) wiring of the battery module or on the negative (b) wiring.

[0067] FIG. 9(a) shows a situation in which an energy storage system operates in normal mode. The first power conversion module can be represented as the Main DCDC, and the second power conversion module as the Sub DCDC. The first switch (1) is in a closed state, connecting the battery to the sub DC-DC converter so that power stored in the battery can be transferred to the sub DC-DC converter. The second switch (2) is also set to a closed state, connecting the battery to the PV DC-DC converter, the main DCDC, and the sub DCDC so that power generated from the solar panel can be stored in the battery and the battery module can be connected to the system.

[0068] The third switch (3) is in the open state, so that the bypass function is disabled and the battery participates normally in the system's power flow. This is the setting used when the battery is operating normally. The fourth switch (4) is in the closed state, connecting the Main DC-DC, the battery module, and the solar panel.

[0069] According to one embodiment, when the control unit (150) determines that an abnormality has occurred according to a predetermined standard and separates the battery module from another battery module, the first switch is closed, the second switch is open, the third switch is closed, and the fourth switch is open, thereby separating the battery module that has an abnormality from another battery module and connecting the power wiring of the solar panel to the second power conversion module.

[0070] If the control unit (150) determines that a specific battery module has an abnormality according to a predetermined standard, it can disconnect the battery module from the system and control a switch to supply power from the solar panel to the system. This operation is performed to prevent the abnormal state of the battery module from affecting the entire system and to continue supplying power using the solar panel.

[0071] Referring to FIG. 9(b), the first power conversion module can be represented as a Main DCDC, and the second power conversion module as a Sub DCDC. In this case, the Sub DCDC can operate as a balancing DCDC. The control unit (150) sets the first switch to a closed state to connect the power of the solar panel to the second power conversion module. At the same time, the second switch is set to an open state to disconnect the faulty battery module from the system. Additionally, the third switch is set to a closed state to bypass the battery module, thereby preventing interruption of the power flow. Finally, the fourth switch is set to an open state to cut off the connection between the faulty battery module and the first power conversion module.

[0072] Through this switch control, the battery module is cut off and safely disconnected, and the power generated from the solar panel can be transferred to a second power conversion module and supplied to the system. This allows the stability and continuity of the energy storage device to be maintained and prevents abnormal conditions from affecting the entire system.

[0073] According to one embodiment, the control unit (150) controls the first to fourth switches to open when the user stops the operation of the energy storage device, and controls the second switch to close when it is determined that over-discharge has occurred based on the state information of the battery module according to a predetermined standard, so that the over-discharged battery module can be charged using the power of the solar panel.

[0074] Referring to FIG. 10(a), the control unit (150) can control all switches from the first to the fourth to be in an open state to completely cut off the power flow within the system when a user issues a command to stop the operation of the energy storage device. This operation stops power transmission by disconnecting the connection between the battery module, the Main DC-DC, Sub DC-DC converters, and the solar panel, and safely switches the system to a stopped state. In this state, the solar panel no longer supplies power to the battery module or the power conversion module, and the battery is also disconnected from other loads.

[0075] On the other hand, if it is determined that over-discharge has occurred according to a predetermined standard based on the status information of the battery module, the control unit (150) controls the second switch to a closed state so that power generated from the solar panel can be transferred to the battery module. The solar panel supplies power converted to an appropriate charging voltage through a PV DC-DC converter to the battery module, and can charge the battery in an over-discharged state. At this time, the first, third, and fourth switches are maintained in an open state so that the connection between the battery module and other loads or power conversion modules is blocked.

[0076] Accordingly, the control unit (150) maintains the safety and efficiency of the system by appropriately controlling each switch in situations where the user needs to stop the system operation or charge the battery module in an over-discharged state. In particular, when the solar panel is operating normally, the battery module can be charged through the PV DC-DC converter, thereby preventing battery damage caused by over-discharge.

[0077] FIG. 10(b) illustrates a method to prevent over-discharge when the solar panel is unable to generate power. In this situation, the control unit (150) recognizes that power cannot be supplied from the solar panel to the battery and appropriately controls the switch to prevent over-discharge of the battery module.

[0078] The control unit (150) can control all switches from the first to the fourth switch to an open state to completely cut off the power flow within the system when the user issues a command to stop the operation of the energy storage device. In the event of over-discharge, the control unit (150) can set the second switch and the first switch to a closed state to connect the battery to the Sub DC-DC converter. Through this, the battery can be charged by receiving power from the Sub DC-DC converter.

[0079] One aspect of the present invention may be implemented as computer-readable code on a computer-readable recording medium. Codes and code segments implementing the above program can be easily inferred by a computer programmer in the art. A computer-readable recording medium may include any type of recording device in which data that can be read by a computer system is stored. Examples of computer-readable recording media may include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical disk, etc. Additionally, a computer-readable recording medium may be distributed across networked computer systems and written and executed as computer-readable code in a distributed manner.

[0080] The present invention has been described above focusing on its preferred embodiments. Those skilled in the art will understand that the present invention may be implemented in modified forms without departing from the essential characteristics of the invention. Accordingly, the scope of the present invention should not be limited to the aforementioned embodiments but should be interpreted to include various embodiments within the scope equivalent to those described in the claims. Explanation of the symbols

[0081] 100: Energy storage device 110: Battery section 120: Battery Management Department 130: Power converter 140: Switch section 150: Control unit

Claims

Claim 1 A battery unit comprising one or more battery modules; a battery management unit comprising one or more battery management systems connected to each of the one or more battery modules; a power conversion unit comprising one or more power conversion modules for charging or discharging the one or more battery modules; and a switch unit comprising one or more switches for controlling the connection of power wiring between the one or more battery modules and the one or more power conversion modules. and a control unit connected to at least one of the one or more battery management systems, the one or more power conversion modules, and the one or more switches, and controlling at least one of the one or more power conversion modules and the one or more switches based on state information of a battery module received from at least one of the one or more battery management systems to control at least one of the voltage and charge state between the one or more battery modules to be uniform within a predetermined range; wherein the power conversion unit includes a first power conversion module connected in series with the one or more battery modules and a second power conversion module connected in parallel with the one or more battery modules; and the switch unit includes a first switch that controls the connection of a power wiring connected to at least one of the positive and negative poles of each of the one or more battery modules in the power wiring between the second power conversion module and the one or more battery modules, a second switch that controls the connection of a power wiring connected to the positive or negative pole of each of the one or more battery modules and the first power conversion module and the second power conversion module, and is located on the load-side power wiring of the second switch and connects the positive and negative poles of each of the one or more battery modules. It includes a third switch for controlling a bypass, wherein the control unit, based on status information of a battery module received from one or more battery management systems, for each of the one or more battery modules, a normal mode in which the battery module operates within a predetermined standard,It is determined to be either a separation mode, in which a battery module is separated from another battery module because it is determined that an abnormality has occurred by deviating from the above-mentioned predetermined criteria, or a balancing mode, in which the battery module operates within the predetermined criteria but an imbalance has occurred between battery modules because the balance between battery modules deviates from a predetermined range based on at least one of voltage and charge state; in the case of a battery module determined to be in normal mode, the first switch is controlled to be open, the second switch to be closed, and the third switch to be open; in the case of a battery module determined to be in separation mode, the first switch is controlled to be open, the second switch to be open, and the third switch to be closed; in the case of a battery module determined to be in balancing mode, the first switch is controlled to be closed, the second switch to be closed, and the third switch to be open; if charging is required for a battery module determined to be in balancing mode, the second power conversion module is controlled to supply power to the battery module determined to be in balancing mode; and if discharging is required for a battery module determined to be in balancing mode, the second power conversion module An energy storage device that controls the second power conversion module to transfer power from the battery module determined by the balancing mode to the outside. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 An energy storage device according to claim 1, further comprising one or more photovoltaic (PV) panels, wherein the one or more photovoltaic panels are each connected in parallel with the one or more battery modules to supply power to the battery modules. Claim 8 In claim 7, the switch unit further includes a fourth switch that controls the connection between the one or more solar panels and the one or more battery modules and the first power conversion module, and the first switch is further connected to the one or more solar panels, an energy storage device. Claim 9 An energy storage device according to claim 8, wherein, when the control unit determines that an abnormality has occurred according to a predetermined standard and separates the battery module from another battery module, the first switch is closed, the second switch is open, the third switch is closed, and the fourth switch is open to separate the battery module that has an abnormality from another battery module, and the power wiring of the solar panel is connected to the second power conversion module. Claim 10 In claim 8, the control unit controls the first to fourth switches to open when the user stops the operation of the energy storage device, and controls the second switch to close when it is determined that over-discharge has occurred based on the status information of the battery module according to a predetermined standard, thereby charging the over-discharged battery module using the power of the solar panel.

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