Battery control device and method

Abstract

A battery control device according to one embodiment of the present invention is a battery control device located in a battery system including a plurality of batteries, and includes at least one processor; and a memory for storing at least one instruction executed through the at least one processor. The at least one instruction may include an instruction for monitoring the voltage of each of the batteries during the process in which the batteries are connected in parallel to a DC link and charged; an instruction for sequentially disconnecting batteries from the DC link as they reach a predetermined target voltage; and an instruction for reconnecting batteries that have been disconnected from the DC link and whose voltage difference from the last battery is within a set range to the DC link once the last battery connected to the DC link has reached the target voltage.

Description

Technical Field

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2024-0061166, filed with the Korean Intellectual Property Office on May 9, 2024, and all of the content disclosed in the document of the Korean patent application is incorporated herein.

[0002] The present invention relates to a battery control device and a control method thereof, and more specifically, to a battery control device applicable to a battery system including a battery having a voltage flat section and a control method thereof.

Background Art

[0003] A secondary battery is a battery that can be reused through charging even after discharge, and can be used as an energy source for small devices such as mobile phones, tablet PCs, and vacuum cleaners, and is also used as an energy source for medium and large devices such as automobiles and smart grid ESSs (Energy Storage Systems).

[0004] A secondary battery is applied to a system in the form of an assembly such as a battery module in which a number of battery cells are connected in series and parallel, or a battery rack in which battery modules are connected in series and parallel according to the requirements of the system. In the case of medium and large devices such as smart grid ESSs, in order to satisfy the required capacity of the device, a high-capacity battery system in which a number of battery racks are connected in parallel can be applied.

[0005] Carbon materials are primarily used as the negative electrode active material in lithium secondary batteries, while lithium-containing cobalt oxide (LiCoO2) is mainly used as the positive electrode active material. Other materials considered include lithium-containing manganese oxide (LiMnO2, LiMn2O4, etc.) and lithium-containing nickel oxide (LiNiO2). Recently, lithium iron phosphate (LiFePO4) compounds have been used as the positive electrode active material in lithium secondary batteries. LFP (Lithium Iron Phosphate) batteries, which use lithium iron phosphate as the positive electrode active material, offer superior thermal stability and cost-effectiveness compared to other types of batteries.

[0006] LFP batteries exhibit a flat characteristic curve, with a voltage plateau in the charging characteristic curve (the curve relating the open-circuit voltage and the State of Charge). This flat characteristic presents a problem in that the State of Charge (SOC) cannot be accurately estimated using the open-circuit voltage during the plateau. Therefore, battery systems using LFP batteries perform an SOC correction process when the battery voltage is in the high-voltage or low-voltage range.

[0007] However, after such SOC correction process is complete, when the battery rack is reconnected in parallel to the DC link, an inrush current may occur in the battery system due to the characteristics of LFP batteries, which cause a rapid voltage drop.

[0008] Related prior literature includes KR 10-2361334. [Overview of the project] [Problems that the invention aims to solve]

[0009] The objective of the present invention, which aims to solve the above-mentioned problems, is to provide a battery control device that prevents inrush current from occurring in a battery system.

[0010] Another objective of the present invention, in order to solve the above-mentioned problems, is to provide a battery control method using such a battery control device. [Means for solving the problem]

[0011] A battery control device according to one embodiment of the present invention for achieving the above objective is a battery control device located in a battery system including a plurality of batteries, and may include at least one processor; and a memory for storing at least one instruction executed through the at least one processor.

[0012] At least one of the above commands may include: a command to monitor the voltage of each of the batteries during the process of the batteries being connected in parallel to the DC link and being charged; a command to sequentially disconnect batteries from the DC link as they reach a predetermined target voltage; and, once the last battery connected to the DC link reaches the target voltage, a command to reconnect any batteries that have been disconnected from the DC link and whose voltage difference from the last battery is within a set range to the DC link.

[0013] The command to sequentially disconnect batteries from the DC link as they reach the target voltage may include a command to send a switch control signal to the battery management device of the battery that has reached the target voltage, causing the switch connecting the battery and the DC link to be switched to the open state.

[0014] The command to sequentially disconnect batteries from the DC link as they reach the target voltage may include a command to correct the State of Charge (SOC) of the batteries that have reached the target voltage and then disconnect them from the DC link.

[0015] The command to sequentially disconnect batteries from the DC link as they reach the target voltage may include a command to correct the State of Charge (SOC) of the last battery connected to the DC link when the last battery reaches the target voltage, while the last battery is still connected to the DC link.

[0016] The command to reconnect the above battery to the above DC link may include a command to reconnect the battery that has been disconnected from the above DC link, whose voltage difference with the last battery is within the above setting range, and whose SOC correction has been completed.

[0017] The command to reconnect the above-mentioned batteries to the above-mentioned DC link may include a command to sequentially reconnect to the above-mentioned DC link any batteries that are not yet reconnected to the above-mentioned DC link and whose voltage difference with the batteries connected to the above-mentioned DC link falls within a set range, during the process of the batteries connected to the above-mentioned DC link being discharged.

[0018] The command to sequentially disconnect batteries from the DC link once they reach the target voltage may include a command to calculate the State of Charge (SOC) of the battery system based on the SOC of the batteries connected to the DC link, and a command to adjust the charging current of the batteries connected to the DC link to decrease by a predetermined amount if the SOC of the battery system is equal to or greater than the set SOC.

[0019] A battery control method according to one embodiment of the present invention for achieving the above-mentioned other objective is a battery control method by a battery control device located in a battery system including a plurality of batteries, and includes the steps of: monitoring the voltage of each of the batteries during the process in which the batteries are connected in parallel to a DC link and charged; sequentially disconnecting batteries from the DC link as they reach a predetermined target voltage; and, when the last battery connected to the DC link reaches the target voltage, reconnecting to the DC link any batteries that have been disconnected from the DC link and whose voltage difference with the last battery is within a set range.

[0020] The step of sequentially disconnecting batteries from the DC link as they reach the target voltage may include sending a switch control signal to the battery management device of the battery that has reached the target voltage, causing the switch connecting the battery and the DC link to be switched to the open state.

[0021] The step of sequentially disconnecting the battery that has reached the target voltage from the DC link may include the step of correcting the SOC (State Of Charge) of the battery that has reached the target voltage and then disconnecting it from the DC link.

[0022] The step of sequentially disconnecting the battery that has reached the target voltage from the DC link may include the step of correcting the SOC of the last battery connected to the DC link while the last battery remains connected to the DC link if the last battery connected to the DC link reaches the target voltage.

[0023] The step of reconnecting the battery to the DC link may include the step of reconnecting to the DC link a battery among the batteries disconnected from the DC link whose voltage difference from the last battery is within the set range and for which the SOC correction has been completed.

[0024] The step of reconnecting the battery to the DC link may include the step of sequentially reconnecting to the DC link a battery among the batteries not yet reconnected to the DC link whose voltage difference from the battery connected to the DC link falls within the set range during the process of discharging the battery connected to the DC link.

[0025] The step of sequentially disconnecting the battery that has reached the target voltage from the DC link may include the step of calculating the SOC of the battery system based on the SOC of the battery connected to the DC link; and, when the SOC of the battery system is greater than or equal to the set SOC, the step of adjusting to attenuate the charging current of the battery connected to the DC link by a predefined magnitude.

Advantages of the Invention

[0028] The present invention can be modified in various ways and has many embodiments; therefore, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this should be understood not as limiting the present invention to specific embodiments, but rather as including all modifications, equivalents, or substitutes that fall within the spirit and technical scope of the present invention. Similar reference numerals are used for similar components in the description of each drawing.

[0029] Terms such as First, Second, A, B, etc., may be used to describe various components, but the components should not be limited by such terms. The terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the First component may be named the Second component, and similarly, the Second component may be named the First component. The term "and / or" includes a combination of multiple related items or one of multiple related items.

[0030] When it is stated that one component is "combined" or "connected" to another component, it should be understood that this may mean that it is directly combined or connected to the other component, but that another component may exist in between. Conversely, when it is stated that one component is "directly combined" or "directly connected" to another component, it should be understood that there is no other component in between.

[0031] The terms used in this application are used solely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless they are clearly different in context. In this application, terms such as “includes” or “having” are intended to specify the presence of features, figures, steps, actions, components, parts, or combinations thereof as described in the specification, and should not be understood to preemptively exclude the presence or possibility of adding one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0032] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as ideal or overly formal unless explicitly defined herein.

[0033] Some terms used in this specification are defined as follows:

[0034] A battery cell is a basic unit that stores electricity, while a battery module refers to an assembly of multiple battery cells that are electrically connected.

[0035] A battery rack refers to a single-structure system assembled by electrically connecting modular units defined by the battery manufacturer, and can be monitored and controlled by a Battery Management System (BMS). A battery rack can consist of multiple battery modules (or battery packs) and one battery protection unit (BPU) or protection device.

[0036] A battery bank can refer to a collection of large-scale battery rack systems, each consisting of multiple battery racks connected in parallel. Monitoring and control of the rack-based battery management systems (RBMS) can be performed through a battery bank-level BMS.

[0037] A battery assembly refers to a collection comprising multiple electrically connected battery cells that is applied to a specific system or device to function as a power source. Here, a battery assembly can mean a battery module, battery pack, battery rack, or battery bank, but the scope of the present invention is not limited to these individuals.

[0038] SOC (State of Charge) represents the current charge level of the battery as a percentage [%], while SOH (State of Health) represents the current state of the battery as a percentage [%] compared to its current or initial state.

[0039] Figure 1 is a block diagram of a typical energy storage system.

[0040] The basic unit of a battery that stores power in an energy storage system (ESS) is usually a battery cell. A series or parallel combination of battery cells forms a battery module, and a large number of battery modules can constitute a battery rack. In other words, a battery rack is a series or parallel combination of battery modules and can be the basic unit of a battery system. Here, depending on the device or system in which the battery is used, a battery module may also be called a battery pack.

[0041] Referring to Figure 1, a single battery rack 10 can include multiple battery modules and one BPU or protection device. The battery rack can be monitored and controlled through a rack BMS (RBMS). The RBMS can monitor the current, voltage, and temperature of each battery rack under its management, calculate the battery's State of Charge (SOC) based on the monitoring results, and control charging and discharging.

[0042] On the other hand, a Battery Protection Unit (BPU) is a device for protecting batteries from abnormal and fault currents on a rack-by-rack basis. A BPU can include a main contactor (MC), fuse, circuit breaker (CB), or disconnect switch (DS). Here, the main contactor can include a positive and negative main contactor. The BPU can control the battery system on a rack-by-rack basis by turning the main contactor on and off according to the control of the Battery Battery Management System (RBMS). The BPU can also protect the batteries from short-circuit currents using a fuse in the event of a short circuit. Thus, a typical battery system can be controlled through protective devices such as a BPU and switchgear.

[0043] On the other hand, each battery section, which consists of numerous batteries and peripheral circuits and devices, is equipped with a BSC (Battery System Controller) 20 that can monitor and control controlled objects such as voltage, current, temperature, and circuit breakers. The BSC is the highest-level control device for a battery system, including a bank-unit battery system that includes multiple battery racks, and can also be used as a control device in battery systems with multiple bank-level structures.

[0044] Furthermore, a Power Conversion System (PCS) 40, provided for each battery section, performs the actual charging and discharging based on charge / discharge commands from the EMS 30. The Power Conversion System may include a power conversion unit (DC / AC inverter) and a controller. On the other hand, the output of each BPU can be connected to a power generation device (e.g., a solar power generation system) and the PCS 40 via a DC link (or DC bus), and the PCS 40 can be connected to the grid. In addition, the Energy Management System (EMS) 30 or Power Management System (PMS) manages the ESS system as a whole.

[0045] Figure 2 shows the charging characteristic curve of the LFP battery.

[0046] More specifically, Figure 2 shows the charging characteristic curve of an LFP (Lithium Iron Phosphate) battery in which lithium iron phosphate oxide is used as the positive electrode active material. The charging characteristic curve shows the correspondence between the open circuit voltage (OCV) measured during the battery charging process and the state of charge (SOC).

[0047] Generally, battery control devices control batteries using their charging characteristic curves. For example, a battery control device can measure the open-circuit voltage of a battery, estimate the battery's state of charge (SOC) based on its charging characteristic curve, and then perform balancing between batteries or control the parallel connection between batteries based on the estimated SOC.

[0048] As shown in Figure 2, the charging characteristic curve of an LFP battery has a voltage plateau in the state of charge (SOC) range of approximately 10% to 90%. In the case of an LFP battery with such a plateau characteristic, it is difficult to accurately estimate the SOC in the plateau range, and accurate estimation is only possible in the non-flat range (for example, the range where the SOC is 90% or higher, or the range where the SOC is 10% or lower).

[0049] Therefore, a battery system in which battery racks, each containing an LFP battery cell, are connected in parallel performs a SOC correction process when the voltage of the battery rack is in a high-voltage or low-voltage range.

[0050] Figure 3 is a graph illustrating a typical battery control method.

[0051] In a battery system using LFP batteries, the battery control unit performs a SOC correction process on battery racks that have reached the high-voltage section.

[0052] If the battery system includes multiple battery racks, racks that reach the high-voltage section are sequentially disconnected from the DC link. Once all racks are disconnected from the DC link, the battery control unit can correct the SOC of each rack. After all racks have been corrected for SOC, all racks are simultaneously connected to the DC link and connected in parallel.

[0053] However, after such a SOC correction process is completed, when the battery rack is reconnected in parallel to the DC link, inrush current may occur in the battery system due to the characteristics of LFP batteries, where the voltage rises or falls sharply in non-flat sections (e.g., sections where the SOC is 90% or higher, or sections where the SOC is 10% or lower).

[0054] For example, as shown in Figure 3, if Rack #1 reaches the target voltage at time t1 and is disconnected from the DC link, then Rack #2 reaches the target voltage at time t2 and is disconnected from the DC link, and then Rack #3 reaches the target voltage at time t3 and is disconnected from the DC link, a high voltage difference will occur between Rack #1, which was disconnected first from the DC link, and Rack #3, which was disconnected last. If Racks #1 through #3 are connected to the DC link simultaneously after the SOC correction process is completed, such a high voltage difference may cause a momentary high inrush current to flow to Rack #1.

[0055] The present invention was devised to solve these problems and relates to a battery control device and method for preventing inrush current from occurring in a battery system.

[0056] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] Figure 4 is a block diagram of a battery system according to an embodiment of the present invention.

[0058] Referring to Figure 4, the battery system according to an embodiment of the present invention may include a plurality of batteries 100, a plurality of battery management devices 200 provided in correspondence with each of the plurality of batteries for managing and controlling the corresponding batteries, and a battery control device 300 that works in conjunction with the plurality of battery management devices 200.

[0059] The battery 100 may be a battery assembly comprising a plurality of unit cells electrically connected to one another. For example, the battery 100 may mean a battery rack, but the scope of the present invention is not limited thereto. That is, the battery 100 according to the present invention may correspond to a battery module, a battery pack, or a battery bank.

[0060] The batteries 100 can be configured by connecting them in parallel. Here, each of the batteries 100 can be electrically connected to a DC link and connected in parallel with the other batteries.

[0061] Each of the batteries 100 may include a switch located on the input / output side. When the switch is switched from the closed state to the open state, the electrical connection to the DC link is disconnected, and the parallel connection with other batteries is released. Conversely, when the switch of battery 100 is switched from the open state to the closed state, it can be electrically connected to the DC link and connected in parallel with other batteries.

[0062] The battery management device 200 can manage and control the corresponding battery 100 by collecting status information about the corresponding battery 100 and performing predefined control operations based on the collected status information. Here, the status information may include one or more of the following: the voltage value and state of charge (SOC) value of the battery, and the voltage value and SOC value of each unit cell contained in the battery.

[0063] The battery management device 200 can control the operation of switches provided on the input and output sides of the battery 100.

[0064] Each of the battery management devices 200 is connected to the battery control device 300 via a network and can transmit battery status information to the battery control device 300 and receive control commands from the battery control device 300 to operate. Here, the battery management device 200 can receive switch control signals from the battery control device 300 to control the operation of the switches and can control the on / off operation of the switches according to the switch control signals.

[0065] The battery control device 300 can monitor and control the operating status of each of the battery management devices 200.

[0066] The battery control device 300 can be a BSC (Battery System Controller), an EMS (Energy Management System), or a PMS (Power Management System).

[0067] The battery control device 300 monitors the voltage of each battery during the charging process while the batteries are connected in parallel to the DC link (online state), and can sequentially disconnect batteries from the DC link once they reach a predetermined target voltage.

[0068] In the process of sequentially switching online batteries to an offline state, if only one battery remains connected to the DC link, the battery control device 300 can select a target battery from among the offline batteries whose voltage difference from the online batteries is within a set range, while the last online battery is connected to the DC link.

[0069] Subsequently, the battery control device 300 can reconnect the selected target battery to the DC link and switch it to an online state.

[0070] Figure 5 is an operation flowchart of the battery control method in charging mode according to an embodiment of the present invention.

[0071] The battery control method according to an embodiment of the present invention can be performed by a battery control device located within a battery system including multiple batteries. Here, the battery control device can correspond to a higher-level control device that works in conjunction with each battery management device of the batteries, and can correspond to, for example, a BSC, EMS, or PMS that works in conjunction with multiple BMSs.

[0072] The battery control device can monitor the voltage of each online battery during the charging process while the batteries are connected in parallel to the DC link (online state) (S510).

[0073] Here, the battery control device can receive the battery voltage, or the voltage of each individual cell, from the battery management device of each battery.

[0074] The battery control device can determine whether any of the online batteries have reached a predefined target voltage (S520). Here, the target voltage can be predefined as the minimum voltage value at which the State of Charge (SOC) can be estimated.

[0075] The battery control device can determine a battery as having reached its target voltage if the maximum voltage value among the voltage values ​​of the unit cells contained in that particular battery reaches the target voltage.

[0076] The battery control device can sequentially disconnect batteries from the DC link as they reach the target voltage, until only one battery remains online.

[0077] Specifically, if the voltage of a particular online battery reaches the target voltage (Y in S520), the battery control unit can determine whether that battery is the last battery connected to the DC link (S530).

[0078] If the battery that has reached the target voltage is not the last online battery (N in S530), the battery control device can disconnect the battery from the DC link and switch it to an offline state (S540). Here, the battery control device can send a switch control signal to the battery management device of the online battery that has reached the target voltage, causing the switch connecting the battery and the DC link to be switched to the open state, thereby disconnecting the battery from the DC link.

[0079] If the battery that has reached the target voltage is the last online battery (Y in S530), the battery control device can select one or more target batteries from among the offline batteries that have been disconnected from the DC link, while the last online battery is connected to the DC link, such that the voltage difference between them and the last online battery is within a set range (S550).

[0080] Subsequently, the battery control device 300 can reconnect the selected target battery to the DC link and switch it to an online state (S560).

[0081] Figures 6 and 7 are reference diagrams illustrating a battery control method in charging mode according to an embodiment of the present invention. Hereinafter, with reference to Figures 6 and 7, a battery system including four battery racks connected in parallel will be used as an example to describe the battery control method according to an embodiment of the present invention.

[0082] The battery control unit can monitor the voltage of each rack (Rack #1 to #4) while they are charging online.

[0083] If, for example, the voltage of Rack #1 reaches the target voltage (e.g., 3.6V) at time t1, the battery control device can disconnect Rack #1 from the DC link at time t1 and switch it to an offline state, as shown in Figure 6.

[0084] Subsequently, if the voltage of Rack #2 reaches the target voltage at time t2, the battery control unit can disconnect Rack #2 from the DC link at time t2 and switch it to an offline state.

[0085] Subsequently, if the voltage of Rack #4 reaches the target voltage at time t3, the battery control unit can disconnect Rack #4 from the DC link at time t3 and switch it to an offline state.

[0086] Subsequently, if the voltage of Rack #3 reaches the target voltage, the battery control unit can select a target rack while Rack #3 remains connected to the DC link, without switching Rack #3 to an offline state.

[0087] For example, as shown in Figure 7, if the voltage value of Rack #3 reaches the target voltage at time t4, the battery control unit can calculate the voltage difference between Rack #3 and the offline racks (Racks #1, 2, and 4). The battery control unit can then select the offline racks whose voltage difference with Rack #3 is within a preset voltage range (e.g., 0.2V) and switch the selected racks online. If all offline racks (Racks #1, 2, and 4) are selected as target racks, then, as shown in Figure 7, all offline racks (Racks #1, 2, and 4) can be reconnected to the DC link and switched online.

[0088] Figure 8 is an operation flowchart of a battery control method according to another embodiment of the present invention.

[0089] The battery control unit can monitor the voltage of each online battery during the charging process (S810).

[0090] The battery control device can determine whether any of the online batteries have reached a predefined target voltage (S820). Here, the target voltage can be predefined as the minimum voltage value at which the State of Charge (SOC) can be estimated.

[0091] If the voltage of a particular online battery reaches the target voltage (Y in S520), the battery control unit can determine whether that battery is the last online battery (S830).

[0092] If the battery that has reached the target voltage is not the last online battery (N in S830), the battery control device can disconnect the battery from the DC link and switch it to an offline state (S840).

[0093] Subsequently, the battery control unit can determine whether the State of Charge (SOC) of the battery system is equal to or greater than the set value (S850).

[0094] Specifically, the battery control unit can calculate the State of Charge (SOC) of the battery system based on the SOC of each online battery currently connected to the DC link.

[0095] In this embodiment, the State of Charge (SOC) of the battery system can be calculated as the average value of the SOCs of the individual online batteries.

[0096] In another embodiment, the State of Charge (SOC) of the battery system can be calculated using the following formula.

[0097]

number

[0098] (Here, SOC max This is the maximum value among the battery SOC values, and SOC min This is the minimum value among the battery's SOC values.

[0099] For example, if the SOCs of the five racks are 100%, 99%, 99.5%, 98%, and 99.5%, the SOC of the battery system can be calculated as 99.2%.

[0100] Subsequently, the battery control device can determine whether the calculated State of Charge (SOC) of the battery system is equal to or greater than a set value (for example, 98%).

[0101] If the State of Charge (SOC) of the battery system is above a set value (Y in S850), the battery control unit can adjust the charging current flowing through the DC link to be attenuated by a predetermined amount (S860).

[0102] In this embodiment, the battery control device can transmit a control signal for adjusting the attenuation of the charging current to a power control device connected to a DC link that controls the charging and discharging power of the battery. For example, the battery control device can transmit a command to the PCS of the battery system to adjust the attenuation of the charging power limit. Here, the PCS can reset the preset charging power limit to a value lowered by a predetermined amount (e.g., 0.05CP) so that the charging current flowing through the DC link is attenuated.

[0103] In another embodiment, the battery control device can transmit a damped charging current value or charging power value to a power control device connected to a DC link that controls the charging and discharging power of the battery. For example, the battery control device can transmit a damped charging power limit value (e.g., 0.05CP) to the PCS of the battery system. The PCS can then reset the preset charging power limit value to the value received from the battery control device so that the charging current flowing through the DC link is damped.

[0104] If the State of Charge (SOC) of the battery system is below a set value (N in S850), the battery control unit can monitor the voltage of the online battery without adjusting the charging current (S810).

[0105] If the battery that has reached the target voltage is the last online battery (Y in S830), the battery control unit may select one or more target batteries from among the offline batteries that have been disconnected from the DC link, while the last online battery is connected to the DC link, such that the voltage difference with the last online battery is within a set range (S870).

[0106] Subsequently, the battery control device 300 can reconnect the selected target battery to the DC link and switch it to an online state (S880).

[0107] In other words, the battery control unit can monitor the state of charge (SOC) of online batteries as they are sequentially switched to the offline state after reaching the target voltage. As the online batteries approach full charge, the battery control unit controls the charging current to decrease, thereby minimizing the increase in the internal resistance (IR) of the online batteries and minimizing the voltage drop of the online batteries due to charging. This minimizes voltage variation between batteries when they are connected in parallel after all batteries have been fully charged.

[0108] Figure 9 is an operation flowchart of a battery control method according to yet another embodiment of the present invention.

[0109] The battery control unit can monitor the voltage of each online battery during the charging process (S910).

[0110] The battery control unit can determine whether any of the online batteries have reached a predefined target voltage (S920). Here, the target voltage can be predefined as the minimum voltage value at which the State of Charge (SOC) can be estimated.

[0111] If the voltage of a particular online battery reaches the target voltage (Y in S920), the battery control unit can correct the state of charge (SOC) of that battery (S925).

[0112] Subsequently, the battery control unit can verify whether the battery in question is the last online battery (S930).

[0113] If the battery that has reached the target voltage is not the last online battery (N in S930), the battery control device can disconnect the battery from the DC link and switch it to an offline state (S940).

[0114] Subsequently, the battery control unit can determine whether the State of Charge (SOC) of the battery system is equal to or greater than a set value (S950). Here, the battery control unit can calculate the SOC of the battery system based on the SOC of each online battery currently connected to the DC link. For example, the battery control unit can calculate the SOC of the battery system using the above formula 1.

[0115] If the State of Charge (SOC) of the battery system is above a set value (Y in S950), the battery control unit can adjust the charging current flowing through the DC link to be attenuated by a predetermined amount (S960).

[0116] If the State of Charge (SOC) of the battery system is below a set value (N in S950), the battery control unit can monitor the voltage of the online battery without adjusting the charging current (S910).

[0117] If the battery that has reached the target voltage is the last online battery (Y in S930), the battery control unit can correct the state of charge (SOC) of the last online battery while the last online battery is connected to the DC link (S935).

[0118] The battery control device can select one or more target batteries from among the offline batteries disconnected from the DC link whose voltage difference with the last online battery is within a set range, and switch the selected target batteries to the online state (S970). In other words, the target batteries may be offline batteries that have been charged to a target voltage and whose SOC correction has been completed, and whose voltage difference with the last online battery is within a set range.

[0119] Subsequently, the battery control unit can check whether there are any offline batteries that are not connected to the DC link (S980). In other words, the battery control unit can check whether there are any offline batteries that have been charged to the target voltage and whose SOC correction has been completed, but whose voltage difference from the last online battery exceeds the set range.

[0120] If offline batteries exist (Y in S980), the battery control unit can select additional target batteries during the discharge process of the currently online batteries (S990) and sequentially switch the selected target batteries to the online state (S970).

[0121] In other words, if all batteries are fully charged and SOC correction is complete, but a voltage difference exists between the batteries, the battery control unit can preferentially switch batteries within the set voltage range, using the voltage of the last fully charged battery as a reference, to the online state. Subsequently, during the discharge process of the online batteries, if the voltage of an online battery reaches the voltage of a specific offline battery, the battery control unit can switch that offline battery to the online state.

[0122] Figure 10 is a reference diagram illustrating a battery control method according to yet another embodiment of the present invention.

[0123] In the following, with reference to Figure 10, a battery control method according to another embodiment of the present invention will be described using a battery system including four battery racks connected in parallel as an example.

[0124] The battery control unit can monitor the voltage of each rack (Rack #1 to #4) while they are charging online.

[0125] The battery control unit can correct the State of Charge (SOC) of online racks that have reached the target voltage until only one online battery remains, and can switch the racks that have completed SOC correction to an offline state. For example, as shown in Figure 10, the remaining racks (Racks #1, #2, and #4), excluding Rack #3, can be sequentially switched to an offline state.

[0126] Subsequently, at time t5, if the voltage of Rack #3 reaches the target voltage, the battery control unit can correct the SOC of Rack #3 while Rack #3 is connected to the DC link and select a target rack where the voltage difference with Rack #3 is within the set voltage range (e.g., 0.2V). If Rack #4 is selected as the target rack, as shown in Figure 10, Rack #4 can be reconnected to the DC link and switched online at time t5.

[0127] Subsequently, as the online racks (Rack #3, #4) are discharged, the battery control unit can select additional target racks and sequentially switch the selected target racks to the online state. For example, at time t6, if the voltage difference between the online racks (Rack #3, #4) and Rack #2 falls within a set range, the battery control unit can switch Rack #2 to the online state. Also, at time t7, if the voltage difference between the online racks (Rack #2, #3, #4) and Rack #1 falls within a set range, the battery control unit can switch Rack #1 to the online state.

[0128] Figure 11 is a block diagram of a battery control device according to an embodiment of the present invention.

[0129] The battery control device 1100 according to an embodiment of the present invention is located within a battery system and can be linked to each battery management device of the battery. For example, the battery control device 1100 may correspond to or be implemented as part of a BSC, EMS, or PMS.

[0130] The battery control device 1100 may include at least one processor 1110, a memory 1120 that stores at least one instruction executed through the processor, and a transceiver 1130 that is connected to a network and performs communication.

[0131] At least one of the above commands may include: a command to monitor the voltage of each of the batteries during the process of the batteries being connected in parallel to the DC link and being charged; a command to sequentially disconnect batteries from the DC link as they reach a predetermined target voltage; and, once the last battery connected to the DC link reaches the target voltage, a command to reconnect any batteries that have been disconnected from the DC link and whose voltage difference from the last battery is within a set range to the DC link.

[0132] The command to sequentially disconnect batteries from the DC link as they reach the target voltage may include a command to send a switch control signal to the battery management device of the battery that has reached the target voltage, causing the switch connecting the battery and the DC link to be switched to the open state.

[0133] The command to sequentially disconnect batteries from the DC link as they reach the target voltage may include a command to correct the State of Charge (SOC) of the batteries that have reached the target voltage and then disconnect them from the DC link.

[0134] The command to sequentially disconnect batteries from the DC link as they reach the target voltage may include a command to correct the State of Charge (SOC) of the last battery connected to the DC link when the last battery reaches the target voltage, while the last battery is still connected to the DC link.

[0135] The command to reconnect the above battery to the above DC link may include a command to reconnect the battery that has been disconnected from the above DC link, whose voltage difference with the last battery is within the above setting range, and whose SOC correction has been completed.

[0136] The command to reconnect the above-mentioned batteries to the above-mentioned DC link may include a command to sequentially reconnect to the above-mentioned DC link any batteries that are not yet reconnected to the above-mentioned DC link and whose voltage difference with the batteries connected to the above-mentioned DC link falls within a set range, during the process of the batteries connected to the above-mentioned DC link being discharged.

[0137] The command to sequentially disconnect batteries from the DC link once they reach the target voltage may include a command to calculate the State of Charge (SOC) of the battery system based on the SOC of the batteries connected to the DC link, and a command to adjust the charging current of the batteries connected to the DC link to decrease by a predetermined amount if the SOC of the battery system is equal to or greater than the set SOC.

[0138] The battery control device 1100 may further include an input interface device 1140, an output interface device 1150, a storage device 1160, and the like. Each component included in the battery control device 1100 can communicate with one another via a bus 1170.

[0139] Here, processor 1110 can mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the method according to the embodiment of the present invention is performed. Memory (or storage device) can consist of at least one of a volatile storage medium and a non-volatile storage medium. For example, memory can consist of at least one of a read-only memory (ROM) and a random access memory (RAM).

[0140] The operation of the method according to an embodiment of the present invention can be embodied as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes all types of recording devices that store data that can be read by a computer system. Furthermore, computer-readable recording media can be distributed across networked computer systems, allowing computer-readable programs or code to be stored and executed in a distributed manner.

[0141] Some aspects of the present invention have been described in the context of apparatus, but they can also be described by corresponding methods, where a block or apparatus corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method can be described by corresponding blocks or items or features of corresponding apparatus. Some or all of the method steps can be carried out by (or using) hardware devices such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps can be carried out by such devices.

[0142] While preferred embodiments of the present invention have been described above with reference to the present invention, those skilled in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as set forth in the following claims. [Explanation of Symbols]

[0143] 100:Battery 200:Battery management device 300, 1100: Battery control device

Claims

1. A battery control device located within a battery system containing multiple batteries, At least one processor; and Includes memory configured to store at least one instruction executed through the at least one processor, The at least one instruction is, A command to monitor the voltage of each of the batteries during the process of charging them while they are connected in parallel to a DC link; A command to sequentially disconnect batteries from the DC link once they reach a predetermined target voltage; and A battery control device that, when the last battery connected to the DC link reaches the target voltage, includes a command to reconnect to the DC link any batteries that have been disconnected from the DC link and whose voltage difference from the last battery is within a set range.

2. The command to sequentially disconnect batteries that have reached the target voltage from the DC link is: The battery control device according to claim 1, comprising a command to send a switch control signal to a battery management device of a battery that has reached the target voltage, causing the switch connecting the battery and the DC link to be switched to the open state.

3. The command to sequentially disconnect batteries that have reached the target voltage from the DC link is: The battery control device according to claim 1, which includes a command to correct the State of Charge (SOC) of a battery that has reached the target voltage and disconnect it from the DC link.

4. The command to sequentially disconnect batteries that have reached the target voltage from the DC link is: The battery control device according to claim 1, which includes an instruction to correct the SOC of the last battery while the last battery connected to the DC link is connected, when the last battery connected to the DC link reaches the target voltage.

5. The command to reconnect the battery to the DC link is: The battery control device according to claim 4, which includes a command to reconnect to the DC link a battery among those disconnected from the DC link whose voltage difference with the last battery is within the set range and whose SOC correction has been completed.

6. The command to reconnect the battery to the DC link is: The battery control device according to claim 1, which includes a command to sequentially reconnect to the DC link any batteries that are not reconnected to the DC link, during the process in which the batteries connected to the DC link are discharged, and whose voltage difference with the batteries connected to the DC link falls within a set range.

7. The command to sequentially disconnect batteries that have reached the target voltage from the DC link is: A command to calculate the State of Control (SOC) of the battery system based on the SOC of the battery connected to the DC link; and The battery control device according to claim 1, further comprising a command to adjust the charging current of the battery connected to the DC link by a predetermined amount if the SOC of the battery system is equal to or greater than a set SOC.

8. A battery control method using a battery control device located within a battery system containing multiple batteries, A step of monitoring the voltage of each of the batteries during the process of charging them while they are connected in parallel to a DC link; A step of sequentially disconnecting batteries that have reached a predetermined target voltage from the DC link; and A battery control method comprising the step of reconnecting to the DC link any batteries that have been disconnected from the DC link and whose voltage difference from the last battery is within a set range, once the last battery connected to the DC link has reached the target voltage.

9. The step of sequentially disconnecting batteries that have reached the target voltage from the DC link is: The battery control method according to claim 8, further comprising the step of sending a switch control signal to a battery management device of a battery that has reached the target voltage, which causes a switch connecting the battery and the DC link to be switched to the open state.

10. The step of sequentially disconnecting batteries that have reached the target voltage from the DC link is: The battery control method according to claim 8, further comprising the step of correcting the State of Charge (SOC) of a battery that has reached the target voltage and disconnecting it from the DC link.

11. The step of sequentially disconnecting batteries that have reached the target voltage from the DC link is: The battery control method according to claim 8, further comprising the step of correcting the SOC of the last battery while the last battery connected to the DC link is connected, once the last battery connected to the DC link reaches the target voltage.

12. The step of reconnecting the battery to the DC link is: The battery control method according to claim 11, further comprising the step of reconnecting to the DC link a battery among those disconnected from the DC link whose voltage difference with the last battery is within the set range and whose SOC correction has been completed.

13. The step of reconnecting the battery to the DC link is: The battery control method according to claim 8, further comprising the step of sequentially reconnecting to the DC link, among the batteries that are not reconnected to the DC link, any batteries whose voltage difference with the batteries connected to the DC link falls within a set range, during the process in which the batteries connected to the DC link are being discharged.

14. The step of sequentially disconnecting batteries that have reached the target voltage from the DC link is: A step of calculating the State of Control (SOC) of the battery system based on the SOC of the battery connected to the DC link; and The battery control method according to claim 8, further comprising the step of adjusting the charging current of the battery connected to the DC link to decrease by a predetermined amount if the SOC of the battery system is equal to or greater than a set SOC.

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