Apparatus and method for controlling battery

Abstract

A battery control device according to an embodiment of the present invention is located in a battery system including a plurality of batteries, and may include: at least one processor; and a memory that stores at least one command executed through the at least one processor. The at least one command may comprise: a command for monitoring the voltage of each of the batteries in a process in which the batteries are connected in parallel to a DC link and charged; a command for sequentially dropping, from the DC link, batteries that have reached a predefined target voltage; and a command for stopping a charging process in a state in which the N batteries are connected to the DC link when only N preset batteries remain connected to the DC link.

Description

Battery control device and method

[0001] This application claims the benefit of Korean Patent Application No. 10-2024-0054522, filed with the Korean Intellectual Property Office on April 24, 2024, the entire contents of which are incorporated herein by reference.

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

[0003] Secondary batteries are batteries that can be reused by 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 are also used as an energy source for medium and large devices such as automobiles and ESS (Energy Storage Systems) for smart grids.

[0004] Secondary batteries are applied to systems in the form of assemblies, such as battery modules, in which multiple battery cells are connected in series and parallel, or battery racks, in which battery modules are connected in series and parallel, depending on the system requirements. For medium- to large-sized devices, such as ESS for smart grids, high-capacity battery systems, in which multiple battery racks are connected in parallel, can be applied to meet the device's capacity requirements.

[0005] Carbon materials are mainly used as negative active materials in lithium secondary batteries, and lithium-containing cobalt oxide (LiCoO2) is mainly used as positive active materials. In addition, the use of lithium-containing manganese oxide (LiMnO2, LiMn2O4, etc.) and lithium-containing nickel oxide (LiNiO2) is also being considered. Recently, lithium iron phosphate (LiFePO4) compounds have been used as positive active materials in lithium secondary batteries. Lithium iron phosphate (LFP) batteries that use lithium iron phosphate as a positive active material are superior to other batteries in terms of thermal stability and cost efficiency.

[0006] LFP batteries exhibit flat characteristics, with a voltage plateau in their charge characteristic curve (the curve relating open circuit voltage to SOC). In this plateau, the open circuit voltage cannot be used to accurately estimate the State of Charge (SOC). Therefore, battery systems employing LFP batteries must periodically charge battery racks to a voltage range where SOC estimation is possible, and then perform a process of calibrating the SOC.

[0007] However, after this SOC correction process is completed, when the battery racks are connected in parallel to the DC link again, an inrush current may occur within the battery system due to the characteristics of LFP batteries that experience a rapid voltage drop.

[0008] Related prior literature includes KR No. 10-2361334.

[0009] An object of the present invention to solve the above problems is to provide a battery control device for preventing inrush current from occurring within a battery system.

[0010] Another object of the present invention to solve the above problems is to provide a battery control method using such a battery control device.

[0011] According to one embodiment of the present invention to achieve the above object, a battery control device is provided, which is located in a battery system including a plurality of batteries, and may include at least one processor; and a memory storing at least one command executed through the at least one processor.

[0012] The at least one command may include a command for monitoring the voltage of each of the batteries while the batteries are connected in parallel to the DC link and being charged; a command for sequentially removing batteries that have reached a predetermined target voltage from the DC link; and a command for stopping the charging process while leaving the N batteries connected to the DC link when only a predetermined number of N batteries remain connected to the DC link.

[0013] The command for monitoring the voltage of each of the batteries may include a command for determining whether the maximum voltage value among the voltage values ​​of the unit cells included in the battery reaches the target voltage.

[0014] The command to sequentially disconnect batteries that have reached the target voltage from the DC link may include a command to transmit a switch control signal to the battery management device of the batteries that have reached the target voltage so that a switch connecting the batteries and the DC link is turned into an open state.

[0015] The command to stop the charging process may include a command to stop the charging process while the last battery is connected to the DC link when only one battery remains connected to the DC link and the last battery reaches the target voltage.

[0016] The at least one command may further include a command to correct the SOC (State Of Charge) of a battery disconnected from the DC link and a battery connected to the DC link after the charging process is stopped.

[0017] The at least one command may further include a command to collectively reconnect batteries disconnected from the DC link to the DC link when the SOC of the batteries connected to the DC link reaches a preset SOC after the charging process is interrupted and the battery system is switched to a standby mode.

[0018] The at least one command may further include a command to sequentially reconnect, to the DC link, batteries that have been disconnected from the DC link during the process of discharging batteries connected to the DC link, the voltage difference between the batteries connected to the DC link and the batteries being connected to the DC link falling within a preset range, when the battery system switches to a discharge mode after the charging process is stopped.

[0019]

[0020] According to one embodiment of the present invention for achieving the above other object, a battery control method is provided, by a battery control device located in a battery system including a plurality of batteries, the method including: a step of monitoring the voltage of each of the batteries while the batteries are connected in parallel to a DC link and charged; a step of sequentially disconnecting batteries that have reached a predetermined target voltage from the DC link; and a step of stopping the charging process while the N batteries are connected to the DC link when only a predetermined number of N batteries remain connected to the DC link.

[0021] The step of monitoring the voltage of each of the batteries may include a step of determining whether the maximum voltage value among the voltage values ​​of the unit cells included in the battery reaches the target voltage.

[0022] The step of sequentially disconnecting batteries that have reached the target voltage from the DC link may include a step of transmitting a switch control signal that causes a switch connecting the battery and the DC link to be switched to an open state to a battery management device of the battery that has reached the target voltage.

[0023] The step of stopping the charging process may include the step of stopping the charging process while the last battery is connected to the DC link when only one battery remains connected to the DC link and the last battery reaches the target voltage.

[0024] The above battery control method may further include a step of correcting the SOC (State Of Charge) of a battery disconnected from the DC link and a battery connected to the DC link after the charging process is stopped.

[0025] The above battery control method may further include a step of reconnecting batteries disconnected from the DC link to the DC link in batches when the SOC of the batteries connected to the DC link reaches a preset SOC when the battery system is switched to a standby mode after the charging process is stopped.

[0026] The above battery control method may further include a step of sequentially reconnecting, to the DC link, batteries that have been disconnected from the DC link during the process of discharging batteries connected to the DC link, the voltage difference between the batteries connected to the DC link and the batteries falling within a preset range, when the battery system switches to a discharge mode after the charging process is stopped.

[0027] According to the above-described embodiment of the present invention, it is possible to prevent inrush current from occurring within a battery system.

[0028] Figure 1 is a block diagram of a typical energy storage system.

[0029] Figure 2 shows the charging characteristic curve of an LFP battery.

[0030] Figure 3 is a graph illustrating a general battery control method.

[0031] Figure 4 is a block diagram of a battery system according to an embodiment of the present invention.

[0032] Figure 5 is an operation flowchart of a battery control method in a charging mode according to an embodiment of the present invention.

[0033] FIG. 6 is a reference diagram for explaining a battery control method in charging mode according to an embodiment of the present invention.

[0034] Figure 7 is an operation flowchart of a battery control method in standby mode according to an embodiment of the present invention.

[0035] FIG. 8 is a reference diagram for explaining a battery control method in standby mode according to an embodiment of the present invention.

[0036] Figure 9 is an operation flowchart of a battery control method in discharge mode according to an embodiment of the present invention.

[0037] Fig. 10 is a reference diagram for explaining a battery control method in discharge mode according to an embodiment of the present invention.

[0038] Figure 11 is a block diagram of a battery control device according to an embodiment of the present invention.

[0039] 100: Battery

[0040] 200: Battery management device

[0041] 300, 1100: Battery control unit

[0042] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0043] Terms such as "first," "second," "A," and "B" may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, the first component could be referred to as the "second component," and similarly, the second component could also be referred to as the "first component." The term "and / or" includes any combination of multiple related items listed or any one of multiple related items listed.

[0044] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0045] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0046] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0047]

[0048] Some terms used in this specification are defined as follows:

[0049] A battery cell is the smallest unit that stores electricity, and a battery module is a collection of multiple battery cells that are electrically connected.

[0050] A battery rack is a single-structure system that electrically connects module units set by a battery manufacturer and can be monitored and controlled through a BMS (Battery Management System). It can be configured to include multiple battery modules (or battery packs) and one BPU or protection device.

[0051] A battery bank can refer to a large-scale battery rack system comprised of multiple battery racks connected in parallel. A battery bank-level BMS can monitor and control the rack BMS (RBMS) at the battery rack level.

[0052] A battery assembly is a collection of multiple electrically connected battery cells that function as a power source when applied to a specific system or device. Here, the battery assembly may refer to a battery module, battery pack, battery rack, or battery bank, but the scope of the present invention is not limited to these entities.

[0053] SOC (State of Charge) is the current charged state of the battery expressed as a percentage [%], and SOH (State of Health) is the current remaining state of the battery expressed as a percentage [%].

[0054]

[0055] Figure 1 is a block diagram of a typical energy storage system.

[0056] In an energy storage system (ESS), the smallest unit of a battery that stores power is typically a battery cell. A series / parallel combination of battery cells forms a battery module, and multiple battery modules can form a battery rack. In other words, a battery rack, consisting of a series / parallel combination of battery modules, can be the smallest unit of a battery system. Depending on the device or system in which the battery is used, a battery module may also be referred to as a battery pack.

[0057] Referring to Fig. 1, a single battery rack (10) may include multiple battery modules and a single BPU or protection device. The battery rack can be monitored and controlled through a Rack Battery Management System (RBMS). The RBMS monitors the current, voltage, and temperature of each battery rack it manages, and based on the monitoring results, calculates the battery's State of Charge (SOC) and controls charging and discharging.

[0058] Meanwhile, the Battery Protection Unit (BPU) is a device that protects batteries from abnormal current and fault current at the rack level. The BPU may include a main contactor (MC), a fuse, a circuit breaker (CB), or a disconnect switch (DS). The main contactor may include a positive main contactor and a negative main contactor. The BPU can control the battery system at the rack level by turning the main contactor on and off under the control of the RBMS. The BPU can also protect the battery from short-circuit current using a fuse in the event of a short-circuit. In this way, a typical battery system can be controlled through protective devices such as the BPU and switch gear.

[0059] Meanwhile, each battery section, which is composed of a plurality of batteries and peripheral circuits, devices, etc., is equipped with a BSC (Battery System Controller) (20) to monitor and control control targets such as voltage, current, temperature, circuit breakers, etc. The BSC is the top-level control device of a battery system including a bank-level battery system including a plurality of battery racks, and is also used as a control device in a battery system having a multiple bank-level structure.

[0060] In addition, the power conversion system (PCS) (40) installed in each battery section is a device that performs actual charging / discharging based on the charging / discharging command from the EMS (30), and may be configured to include a power conversion unit (DC / AC inverter) and a controller. Meanwhile, the output of each BPU may be connected to a power generation device (e.g., a solar power generation device) and the PCS (40) via a DC link (or DC bus), and the PCS (40) may be connected to the grid. In addition, the EMS (Energy Management System) (30) or PMS (Power Management System) manages the ESS system as a whole.

[0061]

[0062] Figure 2 shows the charging characteristic curve of an LFP battery.

[0063] More specifically, Fig. 2 shows the charge characteristic curve of a lithium iron phosphate (LFP) battery using lithium iron phosphate as a positive electrode active material. The charge characteristic curve shows the relationship between the open circuit voltage (OCV) measured during the battery charging process and the SOC.

[0064] Typically, a battery control device controls a battery using its charge characteristic curve. For example, the battery control device may measure the open circuit voltage of the battery, estimate the battery's SOC based on the battery's charge characteristic curve, and then perform balancing between batteries or control parallel connection of the batteries based on the estimated SOC.

[0065] The charge characteristic curve of an LFP battery has a voltage plateau in the SOC range of about 10% to about 90%, as illustrated in Fig. 2. For an LFP battery with such a plateau characteristic, it is difficult to accurately estimate the SOC in the plateau range, and accurate estimation is possible only in uneven ranges (e.g., ranges where the SOC is 90% or higher, or ranges where the SOC is 10% or lower).

[0066] Accordingly, a battery system in which battery racks each containing LFP battery cells are connected in parallel must periodically perform a process of charging the battery racks to a voltage range in which SOC estimation is possible and then correcting the SOC.

[0067]

[0068] Figure 3 is a graph illustrating a general battery control method.

[0069] In a battery system using LFP batteries, the battery control unit performs a charging process until the battery racks reach a predetermined high voltage range (e.g., 3.6 V) to compensate for the SOC of the battery racks.

[0070] Here, racks that reach the high voltage range are sequentially disconnected from the DC link. Once all racks are disconnected from the DC link, the battery control unit can compensate for the SOC of each rack. Once the SOC compensation is complete, all racks are simultaneously connected to the DC link and connected in parallel.

[0071] However, after this SOC correction process is completed, when the battery racks are connected in parallel to the DC link again, an inrush current may occur within the battery system due to the characteristics of LFP batteries, in which the voltage rises or falls rapidly in uneven sections (e.g., sections where the SOC is 90% or higher, or sections where the SOC is 10% or lower).

[0072] For example, as illustrated in FIG. 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 occurs between Rack #1, which is the first to be disconnected from the DC link, and Rack #3, which is the last to be disconnected. After the SOC compensation process is completed, if Racks #1 to #3 are connected to the DC link at the same time, a high inrush current may momentarily flow toward Rack #1 due to this high voltage difference.

[0073] The present invention has been devised to solve such problems, and relates to a battery control device and method for preventing inrush current from occurring in a battery system.

[0074] Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings.

[0075]

[0076] Figure 4 is a block diagram of a battery system according to an embodiment of the present invention.

[0077] Referring to FIG. 4, a battery system according to an embodiment of the present invention may include a plurality of batteries (100), a plurality of battery management devices (200) that are provided corresponding to each of the plurality of batteries and manage and control the corresponding batteries, and a battery control device (300) that is linked to the plurality of battery management devices (200).

[0078] The battery (100) may be a battery assembly comprising a plurality of unit cells electrically connected to each other. For example, the battery (100) may refer to 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.

[0079] The batteries (100) may be configured to be connected in parallel with each other. Here, each of the batteries (100) may be electrically connected to a DC link and connected in parallel with another battery.

[0080] Each of the batteries (100) may include a switch positioned at the input / output terminal. When the switch is switched from a closed state to an open state, the electrical connection with the DC link is cut off, thereby releasing the parallel connection with other batteries. Conversely, when the switch of the battery (100) is switched from an open state to a closed state, the battery (100) is electrically connected to the DC link, thereby allowing the battery to be connected in parallel with other batteries.

[0081] The battery management device (200) can collect status information about the corresponding battery (100) and perform a predefined control operation based on the collected status information, thereby managing and controlling the corresponding battery (100). Here, the status information can include one or more of the voltage value and SOC value of the battery and the voltage value and SOC value of each of the unit cells included in the battery.

[0082] The battery management device (200) can control the operation of a switch provided at the input / output terminal of the battery (100).

[0083] Each of the battery management devices (200) is connected to the battery control device (300) via a network, transmits battery status information to the battery control device (300), and receives control commands from the battery control device (300) to operate. Here, the battery management device (200) receives a switch control signal for controlling the operation of the switch from the battery control device (300), and controls the on / off operation of the switch according to the switch control signal.

[0084] The battery control device (300) can monitor and control the operating status of each of the battery management devices (200).

[0085] The battery control device (300) may correspond to a BSC (Battery System Controller), an EMS (Energy Management System), or a PMS (Power Management System).

[0086] The battery control device (300) can perform a control process defined in response to the operation mode of the battery system.

[0087] When the battery system operates in charging mode, the battery control device (300) can monitor the voltage of each battery while the batteries are connected in parallel to the DC link and being charged, and sequentially disconnect batteries that have reached a predetermined target voltage from the DC link. Here, the battery control device (300) can stop the charging process while leaving the N batteries connected to the DC link when only a preset number of N batteries remain connected to the DC link.

[0088] When the charging process is interrupted, the battery control device (300) can compensate the SOC of the battery disconnected from the DC link and the battery connected to the DC link.

[0089] When the battery system switches from charge mode to standby mode, the battery control device (300) can collectively reconnect the batteries disconnected from the DC link to the DC link when the SOC of the batteries connected to the DC link reaches a preset SOC.

[0090] When the battery system switches from a charge mode to a discharge mode, the battery control device (300) can sequentially reconnect to the DC link, among the batteries disconnected from the DC link during the process of discharging the batteries connected to the DC link, the batteries whose voltage difference with the batteries connected to the DC link falls within a preset range.

[0091]

[0092] Figure 5 is an operation flowchart of a battery control method in a charging mode according to an embodiment of the present invention.

[0093] A battery control method according to an embodiment of the present invention may be performed by a battery control device located within a battery system including a plurality of batteries. Here, the battery control device may correspond to an upper control device that interfaces with the battery management devices of each battery, and may correspond to, for example, a BSC, EMS, or PMS that interfaces with a plurality of BMSs.

[0094] When the battery system operates in charging mode, the battery control device can monitor the voltage of each online battery while the batteries connected in parallel to the DC link (online state) are being charged (S510).

[0095] Here, the battery control device can receive the voltage of the battery, or the voltage of each unit cell, from the battery management device of each battery.

[0096] The battery control device can determine whether any of the batteries has reached a predefined target voltage (S520). Here, the target voltage can be predefined as the minimum voltage value for estimating the SOC.

[0097] The battery control device can determine that the battery has reached the target voltage when the maximum voltage value among the voltage values ​​of the unit cells included in the specific battery reaches the target voltage.

[0098] The battery control unit can sequentially disconnect batteries that have reached a target voltage from the DC link until only a preset number of N batteries remain online.

[0099] Specifically, when the voltage of a specific battery reaches the target voltage (Y of S520), the battery control device can determine whether there are N batteries currently online (S530).

[0100] If there are more than N batteries currently online (N in S530), the battery control unit can switch the batteries to an offline state by disconnecting them from the DC link (S540).

[0101] Here, the battery control device can transmit a switch control signal to the battery management device of the battery that has reached the target voltage so that the switch connecting the battery and the DC link is turned into an open state, thereby causing the battery to be disconnected from the DC link.

[0102] If there are N batteries currently online (Y in S530), the battery control unit can stop the charging process while the online batteries, including the corresponding batteries, remain connected to the DC link.

[0103] That is, the battery control device can switch the online batteries connected to the DC link to the offline state in the order in which they reach the target voltage, and stop the charging process when only a predefined N number of online batteries remain.

[0104] In an embodiment, N may be defined as 1. Here, the battery control device may stop the charging process when only one online battery remains and the last online battery reaches the target voltage, with the last online battery connected to the DC link.

[0105] The purpose of keeping the last battery to reach the target voltage online is to allow the voltage to decrease faster than the batteries that are taken offline.

[0106] When the charging process is interrupted, the battery control unit can compensate the SOC of the offline battery and each of the N online batteries.

[0107]

[0108] FIG. 6 is a reference diagram for explaining a battery control method in charging mode according to an embodiment of the present invention. Hereinafter, referring to FIG. 6, a battery system including four battery racks connected in parallel will be described as an example, and a battery control method in charging mode according to an embodiment of the present invention will be explained.

[0109] The battery control unit can monitor the voltage of each rack (Rack #1 to #4) while the racks are being charged online.

[0110] When the maximum voltage value (hereinafter, maximum cell voltage value) among the voltage values ​​of the unit cells included in Rack #1 at time t1 reaches the target voltage (e.g., 3.6 V), the battery control device can switch Rack #1 to an offline state by disconnecting it from the DC link at time t1.

[0111] Afterwards, when the maximum cell voltage value of Rack #2 reaches the target voltage at time t2, the battery control unit can switch Rack #2 to an offline state by disconnecting it from the DC link at time t2.

[0112] Afterwards, when the maximum cell voltage value 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.

[0113] Thereafter, when the maximum cell voltage value of Rack #3 reaches the target voltage, the battery control unit can stop the charging process while Rack #3 is connected to the DC link without switching Rack #3 to an offline state.

[0114] When the charging process is interrupted, the battery control unit can update the SOC of each of the racks (Rack #1 to #4) based on the voltage value of each of the racks (Rack #1 to #4).

[0115] Meanwhile, when the charging process is interrupted, the voltage of Rack #3, which is online, decreases faster than the voltages of Rack #1, Rack #2, and Rack #4, which were previously switched to offline status.

[0116]

[0117] Figure 7 is an operation flowchart of a battery control method in standby mode according to an embodiment of the present invention.

[0118] After the charging process in the charging mode is stopped and the battery system switches to the standby mode, the battery control device can monitor the SOC of each of the N online batteries (S710).

[0119] Here, the battery control device can receive the SOC value of the online battery from the battery management device of the online battery.

[0120] The battery control device can determine whether the SOC of the online battery reaches a preset SOC (S720).

[0121] When the SOC of the online battery reaches the preset SOC (Y of S720), the battery control device can collectively reconnect the offline batteries to the DC link and switch them to the online state (S730). Here, the SOC setting value (SOC_set) can be defined as the SOC value at the point when the online battery becomes stabilized. If there are multiple online batteries (N is 2 or more), the battery control device can collectively switch the offline batteries to the online state when the SOC of each of the online batteries reaches the preset SOC.

[0122] That is, when the battery system switches from charge mode to standby mode, the battery control device can prevent inrush current from being generated due to the voltage difference by controlling all batteries to be connected in parallel at a point in time when the voltage of the online battery stabilizes after a rapid decrease.

[0123]

[0124] FIG. 8 is a reference diagram for explaining a battery control method in standby mode according to an embodiment of the present invention.

[0125] Hereinafter, with reference to FIG. 8, a battery control method in standby mode according to an embodiment of the present invention will be described using a battery system including four battery racks connected in parallel as an example.

[0126] After the charging process in the charging mode is stopped and the battery system switches to the standby mode, the battery control unit can monitor the SOC of Rack #3, which is an online rack.

[0127] When the SOC of Rack #3 gradually decreases and reaches a preset SOC at time t4, the battery control unit can collectively switch Rack #1, Rack #2, and Rack #4, which are in an offline state, to an online state at time t4.

[0128]

[0129] Figure 9 is an operation flowchart of a battery control method in discharge mode according to an embodiment of the present invention.

[0130] When the battery system switches to the discharge mode after the charging process in the charge mode is stopped, the battery control device can monitor the voltage of each of the online battery and the offline battery during the process of discharging the online battery (S910).

[0131] The battery control device can determine whether there is a battery among offline batteries whose voltage difference with the online battery falls within a preset range (S920).

[0132] Here, the battery control device can calculate a voltage difference between the offline battery and the online battery based on the average cell voltage of the offline battery and the average cell voltage of the online battery.

[0133] The battery control unit can sequentially reconnect offline batteries to the DC link when the voltage difference with the online battery falls within a preset range.

[0134] Specifically, when the voltage difference between a specific offline battery and an online battery becomes less than a set value (Y in S920), the battery control device can reconnect the offline battery to the DC link and switch it to an online state (S930).

[0135] Here, the battery control device can transmit a switch control signal to the battery management device of the offline battery to cause the switch connecting the battery and the DC link to be turned into a closed state, thereby causing the offline battery to be reconnected to the DC link.

[0136] Thereafter, the battery control device can check whether the battery that has been switched online is the last battery (S940), and if it is not the last battery (N of S940), perform steps S910 to S930 until all offline batteries are switched online.

[0137] That is, when the battery system switches from a charge mode to a discharge mode, the battery control device can prevent an inrush current from being generated due to a voltage difference by controlling the off-line battery to be individually connected to the DC link at a point in time when the voltage of the off-line battery approaches the voltage of the on-line battery.

[0138]

[0139] Fig. 10 is a reference diagram for explaining a battery control method in discharge mode according to an embodiment of the present invention.

[0140] Hereinafter, with reference to FIG. 10, a battery control method in a discharge mode according to an embodiment of the present invention will be described using a battery system including four battery racks connected in parallel as an example.

[0141] The battery control unit can monitor the voltage of each of the racks (Rack #1 to #4) while Rack #3, which is an online rack, is being discharged.

[0142] When the voltage of Rack #3, which is in an online state, gradually decreases and reaches the voltage of Rack #4 at time t5, the battery control unit can switch Rack #4, which is in an offline state, to an online state at time t5.

[0143] Afterwards, when the voltages of Rack #3 and Rack #4, which are in an online state, gradually decrease and reach the voltage of Rack #2 at time t6, the battery control unit can switch Rack #2, which is in an offline state, to an online state at time t6.

[0144] Afterwards, when the voltages of Rack #2, Rack #3, and Rack #4, which are in an online state, gradually decrease and reach the voltage of Rack #1 at time t7, the battery control unit can switch Rack #1, which is in an offline state, to an online state at time t7.

[0145] Afterwards, all racks (Rack #1 to #4) can be discharged in a state where they are connected in parallel to the DC link.

[0146]

[0147] Figure 11 is a block diagram of a battery control device according to an embodiment of the present invention.

[0148] The battery control device (1100) according to an embodiment of the present invention is positioned within a battery system and can be interoperable with the battery management devices of each battery. For example, the battery control device (1100) may correspond to a BSC, an EMS, or a PMS, or may be implemented as an integral part of any of these.

[0149] The battery control device (1100) may include at least one processor (1110), a memory (1120) that stores at least one command executed through the processor, and a transmission / reception device (1130) that is connected to a network and performs communication.

[0150] The at least one command may include a command for monitoring the voltage of each of the batteries while the batteries are connected in parallel to the DC link and being charged; a command for sequentially removing batteries that have reached a predetermined target voltage from the DC link; and a command for stopping the charging process while leaving the N batteries connected to the DC link when only a predetermined number of N batteries remain connected to the DC link.

[0151] The command for monitoring the voltage of each of the batteries may include a command for determining whether the maximum voltage value among the voltage values ​​of the unit cells included in the battery reaches the target voltage.

[0152] The command to sequentially disconnect batteries that have reached the target voltage from the DC link may include a command to transmit a switch control signal to the battery management device of the batteries that have reached the target voltage so that a switch connecting the batteries and the DC link is turned into an open state.

[0153] The command to stop the charging process may include a command to stop the charging process while the last battery is connected to the DC link when only one battery remains connected to the DC link and the last battery reaches the target voltage.

[0154] The at least one command may further include a command to correct the SOC (State Of Charge) of a battery disconnected from the DC link and a battery connected to the DC link after the charging process is stopped.

[0155] The at least one command may further include a command to collectively reconnect batteries disconnected from the DC link to the DC link when the SOC of the batteries connected to the DC link reaches a preset SOC after the charging process is interrupted and the battery system is switched to a standby mode.

[0156] The at least one command may further include a command to sequentially reconnect, to the DC link, batteries that have been disconnected from the DC link during the process of discharging batteries connected to the DC link, the voltage difference between the batteries connected to the DC link and the batteries being connected to the DC link falling within a preset range, when the battery system switches to a discharge mode after the charging process is stopped.

[0157] The battery control device (1100) may further include an input interface device (1140), an output interface device (1150), a storage device (1160), etc. Each component included in the battery control device (1100) may be connected by a bus (1170) and communicate with each other.

[0158] Here, the processor (1110) may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. The memory (or storage device) may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory may be composed of at least one of a read-only memory (ROM) and a random access memory (RAM).

[0159] The operations of the method according to an embodiment of the present invention can be implemented as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes any type of recording device that stores data readable by a computer system. Furthermore, a computer-readable recording medium can be distributed across network-connected computer systems, allowing the computer-readable program or code to be stored and executed in a distributed manner.

[0160] While some aspects of the present invention have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most significant method steps may be performed by such a device.

[0161] Although the present invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. A battery control device located within a battery system including a plurality of batteries, at least one processor; and A memory that stores at least one instruction to be executed through at least one processor, At least one of the above commands, A command to monitor the voltage of each of the batteries while the batteries are connected in parallel to the DC link and charged; A command to sequentially disconnect batteries from the DC link that have reached a predetermined target voltage; and A battery control device comprising a command to stop a charging process while the N batteries are connected to the DC link when only a preset number of N batteries remain connected to the DC link.

2. In claim 1, The command to monitor the voltage of each of the above batteries is: A battery control device including a command for determining whether the maximum voltage value among the voltage values ​​of the unit cells included in the battery reaches the target voltage.

3. In claim 1, A command to sequentially disconnect batteries that have reached the target voltage from the DC link is: A battery control device comprising a command for transmitting a switch control signal to a battery management device of a battery that has reached the target voltage, the switch controlling signal causing the switch connecting the battery and the DC link to be turned into an open state.

4. In claim 1, The command to stop the above charging process is: A battery control device comprising a command to stop the charging process while the last battery is connected to the DC link when only one battery remains connected to the DC link and the last battery reaches the target voltage.

5. In claim 1, At least one of the above commands, A battery control device further comprising a command for correcting the SOC (State Of Charge) of a battery disconnected from the DC link and a battery connected to the DC link after the charging process is stopped.

6. In claim 1, At least one of the above commands, After the above charging process is interrupted, if the battery system switches to standby mode, A battery control device further comprising a command to collectively reconnect batteries disconnected from the DC link to the DC link when the SOC of the batteries connected to the DC link reaches a preset SOC.

7. In claim 1, At least one of the above commands, After the above charging process is interrupted, if the battery system switches to discharge mode, A battery control device further comprising a command to sequentially reconnect, to the DC link, batteries among those disconnected from the DC link, whose voltage difference with respect to the batteries connected to the DC link falls within a preset range during the process of discharging the batteries connected to the DC link.

8. A battery control method by a battery control device located in a battery system including a plurality of batteries, A step of monitoring the voltage of each of the batteries during the process of charging the batteries while they are connected in parallel to the 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 stopping a charging process while the N batteries are connected to the DC link when only a preset number of N batteries remain connected to the DC link.

9. In claim 8, The step of monitoring the voltage of each of the above batteries is: A battery control method, comprising a step of determining whether the maximum voltage value among the voltage values ​​of the unit cells included in the battery reaches the target voltage.

10. In claim 8, The step of sequentially disconnecting the batteries that have reached the target voltage from the DC link is as follows: A battery control method comprising the step of transmitting a switch control signal to a battery management device of a battery that has reached the target voltage, the switch controlling signal causing a switch connecting the battery and the DC link to be turned into an open state.

11. In claim 8, The step of stopping the above charging process is: A battery control method, comprising the step of stopping the charging process while the last battery is connected to the DC link when only one battery remains connected to the DC link and the last battery reaches the target voltage.

12. In claim 8, A battery control method further comprising the step of correcting the SOC (State Of Charge) of a battery disconnected from the DC link and a battery connected to the DC link after the charging process is stopped.

13. In claim 8, After the above charging process is interrupted, if the battery system switches to standby mode, A battery control method further comprising a step of reconnecting batteries disconnected from the DC link to the DC link in batches when the SOC of the batteries connected to the DC link reaches a preset SOC.

14. In claim 8, After the above charging process is interrupted, if the battery system switches to discharge mode, A battery control method further comprising a step of sequentially reconnecting, to the DC link, batteries among those disconnected from the DC link, whose voltage difference with respect to the batteries connected to the DC link falls within a preset range during the process of discharging the batteries connected to the DC link.

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