Battery control apparatus and method

Abstract

A battery control device according to an embodiment of the present invention may include: at least one processor; and a memory configured to store at least one instruction executed by the at least one processor. Here, the at least one instruction may include: an instruction to monitor a voltage of each of the batteries while the batteries are connected in parallel to a direct current (DC) link and are charged; an instruction to sequentially disconnect at least one battery having reached a predetermined target voltage from the DC link; and an instruction to reconnect, to the DC link, one or more of the at least one batteries disconnected from the DC link, the one or more batteries having a voltage difference from the last battery within a set range when the last battery connected to the DC link reaches the target voltage.

Description

TECHNICAL FIELD

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0061166, filed on May 9, 2024, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to a battery control device and a control method thereof, and more particularly, to a battery control device and a control method thereof suitable for a battery system including a battery having a voltage plateau section. BACKGROUND

[0003] A secondary battery, which can be recharged and reused, can be used as an energy source for small-sized devices such as mobile phones, tablet PCs, and vacuum cleaners, and also can be used as an energy source for medium-to-large-sized devices such as cars and smart grids.

[0004] A secondary battery can be applied to a system in the form of an assembly such as a battery module in which a plurality of battery cells are connected in series and in parallel or a battery rack in which battery modules are connected in series and in parallel according to system requirements. For medium-to-large-sized devices such as a smart grid energy storage system (ESS), a high-capacity battery system having a plurality of battery racks connected in parallel can be applied to satisfy the capacity required for the device.

[0005] A carbon material is mainly used as an anode active material for a lithium secondary battery, and a lithium cobalt oxide (LiCoO2) is mainly used as a cathode active material. In addition, a lithium manganese oxide (LiMnO2, LiMn2O4, etc.) and a lithium nickel oxide (LiNiO2) are also considered. Recently, a lithium iron phosphate (LiFePO4)-based compound has been used as a cathode active material for a lithium secondary battery. A lithium iron phosphate (LFP) battery using lithium iron phosphate as a cathode active material is excellent in thermal stability and cost efficiency compared to other types of batteries.

[0006] However, the LFP battery exhibits a flat characteristic having a voltage plateau in a charging characteristic curve (a curve of a relationship between an open circuit voltage and an SOC), and thus a problem occurs in that the SOC (state of charge) cannot be accurately estimated in the plateau section. Therefore, when the battery voltage is in a high voltage range or a low voltage range, a battery system having the LFP battery performs an SOC compensation process.

[0007] However, when the battery rack is reconnected in parallel with the DC link after the SOC compensation process is completed, a surge current can occur in the battery system due to the characteristic that the LFP battery experiences a rapid voltage drop.

[0008] Among the prior art documents related to the present invention, KR 10-2361334 has some relevance. SUMMARY

[0009] [PROBLEMS TO BE SOLVED BY THE INVENTION]

[0010] To avoid one or more problems of the related art, embodiments of the present disclosure provide a battery control device for preventing inrush current from occurring in a battery system.

[0011] To avoid one or more problems of the related art, embodiments of the present disclosure also provide a battery control method performed by a battery control device.

[0012] [TECHNICAL SOLUTION]

[0013] To achieve the object of the present disclosure, a battery control device can include at least one processor, and a memory for storing at least one instruction executed by the at least one processor.

[0014] Here, the at least one instruction can include an instruction to monitor a voltage of each of the batteries while the batteries are connected in parallel to a direct current (DC) link and are charged, an instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link, and an instruction to reconnect one or more batteries, among the at least one battery disconnected from the DC link, to the DC link when a last battery connected to the DC link reaches the target voltage, the one or more batteries having a voltage difference within a set range from a voltage of the last battery.

[0015] The instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link can include an instruction to transmit a switch control signal for switching a switch connecting the battery and the DC link to an off state to a battery management device of the at least one battery that has reached the predetermined target voltage.

[0016] The instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link can include an instruction to correct a state of charge (SOC) of the at least one battery that has reached the predetermined target voltage and disconnect the at least one battery from the DC link.

[0017] The instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link can include an instruction to correct an SOC of a last battery connected to the DC link while the last battery is connected to the DC link when the last battery reaches the target voltage.

[0018] The instruction to reconnect one or more batteries to the DC link can include an instruction to reconnect, among at least one battery disconnected from the DC link, at least one battery whose voltage difference from the last battery is within a set range and for which SOC correction is completed, to the DC link.

[0019] The instruction to reconnect one or more batteries to the DC link can include an instruction to sequentially reconnect, among at least one battery not reconnected to the DC link, one or more batteries whose voltage difference from at least one battery connected to the DC link falls within a set range, to the DC link during a process of discharging at least one battery connected to the DC link.

[0020] The instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link can include an instruction to calculate an SOC of the battery system based on an SOC of at least one battery connected to the DC link, and an instruction to adjust a charging current of at least one battery connected to the DC link by a predetermined amount if the SOC of the battery system is equal to or greater than a determined SOC.

[0021] According to another embodiment of the disclosure, a battery control method performed by a battery control device located in a battery system including a plurality of batteries can include monitoring a voltage of each of the batteries while the batteries are connected in parallel to a direct current (DC) link and are charged, sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link, and reconnecting one or more batteries, among at least one battery disconnected from the DC link, whose voltage difference from the last battery is within a set range, to the DC link when the last battery connected to the DC link reaches the target voltage.

[0022] The sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link can include transmitting a switch control signal for switching a switch connecting the battery and the DC link to a disconnected state to a battery management device of at least one battery that has reached a predetermined target voltage.

[0023] The sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link can include correcting a state of charge (SOC) of at least one battery that has reached a predetermined target voltage and disconnecting the at least one battery from the DC link.

[0024] The sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link can include correcting an SOC of the last battery while the last battery is connected to the DC link when the last battery connected to the DC link reaches the target voltage.

[0025] Reconnecting one or more batteries to the DC link can include reconnecting at least one battery among the at least one battery disconnected from the DC link, which has a voltage difference from the last battery within a set range and for which SOC correction is completed, to the DC link.

[0026] Reconnecting one or more batteries to the DC link can include sequentially reconnecting one or more batteries among the at least one battery not reconnected to the DC link, which has a voltage difference from the at least one battery connected to the DC link within a set range, to the DC link during a process of discharging the at least one battery connected to the DC link.

[0027] Sequentially disconnecting at least one battery having reached a predetermined target voltage from the DC link can include calculating an SOC of the battery system based on an SOC of at least one battery connected to the DC link, and adjusting a charging current of at least one battery connected to the DC link by a predetermined amount if the SOC of the battery system is equal to or greater than a determined SOC.

[0028] [Advantageous Effects]

[0029] According to the embodiment of the present application as described above, it is possible to prevent inrush current from occurring in the battery system. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a block diagram of a general energy storage system.

[0031] Figure 2 shows a charge characteristic curve of an LFP battery.

[0032] Figure 3 is a graph for explaining a general battery control method.

[0033] Figure 4 is a block diagram of a battery system according to an embodiment of the present application.

[0034] Figure 5 is an operation flowchart of a battery control method according to an embodiment of the present application.

[0035] Figure 6 and Figure 7 is a reference diagram for explaining a battery control method in a charging mode according to an embodiment of the present application.

[0036] Figure 8 is an operation flowchart of a battery control method according to another embodiment of the present application.

[0037] Figure 9 is an operation flowchart of a battery control method according to another embodiment of the present application.

[0038] Figure 10 is a reference diagram for explaining a battery control method according to another embodiment of the present application.

[0039] Figure 11 is a block diagram of a battery control apparatus according to an embodiment of the present application.

[0040] 100: battery

[0041] 200: battery management apparatus

[0042] 300, 1100: battery control apparatus DETAILED DESCRIPTION

[0043] The present application can be modified in various forms and has various embodiments, and specific embodiments thereof are shown in the drawings by way of example and will be described in detail below. It should be understood, however, that the present application is not intended to be limited to a particular embodiment, but rather, the present application is intended to cover all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present application. Throughout the drawings, the same reference numerals refer to the same elements.

[0044] It will be understood that, although the terms such as first, second, A, B can be used herein to describe various elements, the elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present application. As used herein, the term "and / or" includes a combination of the plurality of associated listed items or any one of the plurality of associated listed items.

[0045] It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements present.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", when used herein, specify the presence of stated features, integers, steps, operations, elements, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0047] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0048] Some of the terms used herein are defined as follows.

[0049] A battery cell is a basic unit for storing electric power, and a battery module refers to an assembly in which a plurality of battery cells are electrically connected.

[0050] A battery rack refers to a system of a single structure assembled by connecting module units arranged in series / parallel by a battery manufacturer, and can be monitored and controlled by a battery management device / system (BMS). The battery rack can include several battery modules and a battery protection unit or any other protection device.

[0051] A battery bank refers to a large battery rack system configured by connecting a plurality of battery racks in parallel. A bank BMS for the battery bank can monitor and control several rack BMSs, each of which manages a battery rack.

[0052] A battery assembly can include a plurality of electrically connected battery cells, and refers to an assembly used as a power source by being applied to a specific system or device. Here, the battery assembly can mean a battery module, a battery pack, a battery rack, or a battery bank, but the scope of the present application is not limited to these entities.

[0053] A state of charge (SOC) refers to a current state of charge of a battery, expressed in percentage points [%], and a state of health (SOH) can be a current state of a battery compared to its ideal or original condition, expressed in percentage points [%].

[0054] Figure 1 is a block diagram of a general energy storage system.

[0055] In an energy storage system (ESS), a basic unit of a battery for storing energy or electric power is a battery cell. In general, a series / parallel combination of battery cells can form a battery module, and a plurality of battery modules can form a battery rack. In other words, a battery rack, which is a series / parallel combination of battery modules, can be a basic unit of a battery system. Here, depending on a device or system in which a battery is used, a battery module can be referred to as a battery pack.

[0056] Reference Figure 1The battery rack 10 can include a plurality of battery modules and a battery protection unit or any other protection device. The battery rack can be monitored and controlled by a rack battery management system (RBMS). The RBMS can monitor the current, voltage, and temperature of each battery rack to be managed, calculate the state of charge (SOC) of the battery based on the monitoring results, and control charging and discharging.

[0057] Meanwhile, the battery protection unit (BPU) is a device for protecting the battery from abnormal and fault currents in the battery rack. The BPU can include a main contactor (MC), a fuse, a circuit breaker (CB), or a disconnecting switch (DS). Here, the main contactor can include a positive main contactor and a negative main contactor. The BPU can control the battery system rack by rack by controlling the turn-on / off of the main contactor according to the control of the RBMS. The BPU can also protect the battery from short circuit current by using a fuse when a short circuit occurs. In this way, the existing battery system can be controlled by a protection device such as the BPU or a switch gear.

[0058] In addition, a battery system controller (BSC) 20 can be located in each battery section including a plurality of batteries, peripheral circuits, and devices in order to monitor and control objects such as voltage, current, temperature, and a circuit breaker. The battery system controller can be a top-level controller of a battery system of a library level including a plurality of battery racks, and also serves as a controller in a battery system having a plurality of library level structures.

[0059] In addition, a power conversion system (PCS) 40 installed in each battery section can perform actual charging / discharging based on a charge / discharge command from an energy management system (EMS) 30. The power conversion system can include a DC / AC inverter and a controller. Meanwhile, the output of each BPU can be connected to a power generation device (for example, a photovoltaic system) and the PCS 40 connected to a power grid through a DC link (or a DC bus). In addition, the energy management system (EMS) 30 or the power management system (PMS) can control the energy storage system as a whole.

[0060] Figure 2 A charge characteristic curve of an LFP battery is shown.

[0061] More specifically, Figure 2 A charge characteristic curve of a lithium iron phosphate (LFP) battery in which lithium iron phosphate is used as a positive active material is shown. The charge characteristic curve represents a correspondence between an open circuit voltage (OCV) and an SOC measured during a battery charging process.

[0062] Generally, a battery control device controls a battery by using a charge characteristic curve of the battery. For example, the battery control device can measure an open-circuit voltage value of the battery, estimate an SOC of the battery based on a charge characteristic curve of the battery, and perform balancing between the batteries or control parallel connection between the batteries based on the estimated SOC.

[0063] Referring to Figure 2 , a charge characteristic curve of an LFP battery has a voltage plateau in a SOC range of about 10% to about 90%. In the case of an LFP battery having such a plateau characteristic, it is difficult to accurately estimate the SOC in the plateau section, and thus accurate estimation is only possible in a non-plateau section (e.g., a section in which the SOC is greater than 90% or a section in which the SOC is less than 10%).

[0064] Accordingly, a battery system in which battery racks each including LFP battery cells are connected in parallel performs an SOC compensation process when the voltage of the battery racks is in a high voltage range or a low voltage range.

[0065] Figure 3 is a graph for explaining a general battery control method.

[0066] In a battery system applying one or more LFP batteries, a battery control device can perform an SOC correction process on a battery rack that has reached a high voltage section.

[0067] If a plurality of battery racks are included in the battery system, racks that have reached a high voltage section are sequentially removed from a direct current (DC link), and if all of the racks are removed from the DC link, the battery control device can correct the SOC of each rack. When the SOC correction of all of the racks is completed, all of the racks are simultaneously connected to the DC link and connected in parallel to each other.

[0068] However, when the battery racks are again connected in parallel to the DC link after the completion of this SOC correction process, a surge current can occur in the battery system due to the characteristics of the LFP battery in which the voltage rapidly increases or decreases in a non-plateau section (e.g., a section in which the SOC is 90% or more, or a section in which the SOC is 10% or less).

[0069] For example, as Figure 3 shown, if rack #1 reaches a target voltage at time t1 and is removed from the DC link, rack #2 reaches a target voltage at time t2 and is removed from the DC link, and then rack #3 reaches a target voltage at time t3 and is removed from the DC link, a high voltage difference occurs between rack #1, which is first removed from the DC link, and rack #3, which is last removed from the DC link. When rack #1 to rack #3 are simultaneously connected to the DC link after the completion of the SOC correction process, a high surge current can temporarily flow to rack #1 due to this high voltage difference.

[0070] The present invention has been made to solve this problem, and relates to a battery control apparatus and method for preventing inrush current from occurring in a battery system.

[0071] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0072] Figure 4 is a block diagram of a battery system according to an embodiment of the present invention.

[0073] Referring to Figure 4 A battery system according to an embodiment of the present invention can include a plurality of batteries 100, a plurality of battery management apparatuses 200 disposed corresponding to each of the plurality of batteries and managing and controlling the corresponding battery, and a battery control apparatus 300 connected to and interoperating with the plurality of battery management apparatuses 200.

[0074] The battery 100 can be a battery assembly including a plurality of unit cells electrically connected to each other. For example, the battery 100 can mean a battery rack, but the scope of the present invention is not limited thereto. In other words, the battery 100 according to the present invention can correspond to a battery module, a battery pack, or a battery bank.

[0075] The batteries 100 can be configured to be connected in parallel to each other. Here, each battery 100 can be electrically connected to a direct current (DC) link and connected in parallel to other batteries.

[0076] Each battery 100 can include a switch disposed at an input / output terminal, and when the switch is switched from a closed state to an open state, the electrical connection to the DC link is cut off and the parallel connection to another battery can be released. Conversely, when the switch of the battery 100 is switched from the open state to the closed state, the battery 100 can be electrically connected to the DC link and can be connected in parallel to other batteries.

[0077] The battery management apparatus 200 can collect state information about the corresponding battery 100, and perform a predetermined control operation based on the collected state information, thereby managing and controlling the corresponding battery 100. Here, the state information can include at least one of a voltage value and an SOC value of the battery, and a voltage value and an SOC value of each unit cell included in the battery.

[0078] The battery management apparatus 200 can control the operation of the switch disposed at the input / output terminal of the battery 100.

[0079] Each battery management device 200 can be connected to the battery control device 300 through a network, transmit battery state information to the battery control device 300, and receive a control command from the battery control device 300 to operate. Here, the battery management device 200 can receive a switch control signal for controlling the operation of a switch from the battery control device 300, and control the on / off operation of the switch according to the switch control signal.

[0080] The battery control device 300 can monitor and control the operating state of each battery management device 200.

[0081] The battery control device 300 can correspond to a battery system controller (BSC), an energy management system (EMS), or a power management system (PMS).

[0082] The battery control device 300 can monitor the voltage of each battery during a process in which the battery is charged in a state in which the battery is connected in parallel to a DC link (an on-line state), and sequentially disconnect the connection of the battery, which has reached a predetermined target voltage, to the DC link.

[0083] In a process in which the on-line batteries are sequentially switched to an off-line state, when only one battery connected to the DC link remains, the battery control device 300 can select a target battery, which has a voltage difference from the on-line battery within a set range, among the off-line batteries while the last on-line battery is connected to the DC link.

[0084] Thereafter, the battery control device 300 can reconnect the selected target battery to the DC link and switch it to the on-line state.

[0085] Figure 5 is an operation flowchart of a battery control method in a charging mode according to an embodiment of the present application.

[0086] The battery control method according to an embodiment of the present application can be performed by a battery control device located in a battery system including a plurality of batteries. Here, the battery control device can correspond to an upper layer control device connected to and inter-operating with a battery management device of each battery, and can correspond to, for example, a BSC, an EMS, or a PMS connected to and inter-operating with a plurality of battery management systems (BMSs).

[0087] The battery control device can monitor the voltage of each on-line battery during a process in which the battery is charged in a state in which the battery is connected in parallel to a DC link (an on-line state) (S510).

[0088] 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.

[0089] The battery control device can detect one or more batteries among the online batteries that have reached a predetermined target voltage (S520). Here, the target voltage can be predetermined as a minimum voltage value according to which the SOC can be estimated.

[0090] The battery control device can determine a corresponding battery as a battery that has reached the target voltage when a maximum voltage value among voltage values of the unit cells included in the corresponding battery reaches the target voltage.

[0091] The battery control device can sequentially remove the batteries that have reached the target voltage from the DC link until only one battery remains online.

[0092] Specifically, when the voltage of a particular online battery reaches the target voltage (Yes in S520), the battery control device can check whether the battery is the last battery connected to the DC link (S530).

[0093] If the battery that has reached the target voltage is not the last online battery (No in S530), the battery control device can remove the battery from the DC link and switch it to the offline state (S540). Here, the battery control device can transmit a switch control signal that switches a switch connecting the battery and the DC link to the off state to the battery management device of the online battery that has reached the target voltage, thereby removing the battery from the DC link.

[0094] If the battery that has reached the target voltage is the last online battery (Yes in S530), the battery control device can select one or more target batteries having a voltage difference from the last online battery within a set range among offline batteries that have been disconnected from the DC link while the last online battery is connected to the DC link (S550).

[0095] Thereafter, the battery control device 300 can reconnect the one or more selected target batteries to the DC link and switch the batteries to the online state (S560).

[0096] Figure 6 and Figure 7 is a reference diagram for explaining a battery control method in a charging mode according to an embodiment of the present application. Hereinafter, with reference to Figure 6 and Figure 7 , a battery system including four battery racks connected in parallel will be used as an example to explain the battery control method according to an embodiment of the present application.

[0097] The battery control device can monitor the voltage of each of the racks (rack #1 to rack #4) during the charging process of the racks in the online state.

[0098] If the voltage of rack #1 reaches the target voltage (e.g., 3.6 V) at time t1, as inFigure 6 As shown, the battery control device can disconnect frame #1 from the DC link and switch it to offline state at time t1.

[0099] Subsequently, if the voltage of rack #2 reaches the target voltage at time t2, the battery control device can disconnect rack #2 from the DC link and switch it to offline state at time t2.

[0100] Subsequently, if the voltage of rack #4 reaches the target voltage at time t3, the battery control device can switch rack #4 to offline state by disconnecting rack #4 from the DC link at time t3.

[0101] Subsequently, if the voltage of rack #3 reaches the target voltage, the battery control unit can select at least one target rack while rack #3 is connected to the DC link, without switching rack #3 to offline status.

[0102] For example, such as Figure 7 As shown, if the voltage of rack #3 reaches the target voltage at time t4, the battery control device can calculate the voltage difference between rack #3 and the offline racks (rack #1, rack #2, rack #4). Then, the battery control device can select a rack among the offline racks whose voltage difference with rack #3 is within a preset voltage range (e.g., 0.2V) and switch the selected rack to online status. If all offline racks (rack #1, rack #2, rack #4) are selected as target racks, all offline racks (rack #1, rack #2, rack #4) can be reconnected to the DC link and brought online, as shown. Figure 7 As shown.

[0103] Figure 8 This is an operation flowchart of a battery control method according to another embodiment of the present invention.

[0104] The battery control device can monitor the voltage of each online battery during the charging process (S810).

[0105] The battery control device can detect one or more batteries in the online battery that have reached a predetermined target voltage (S820). Here, the target voltage can be predetermined as the minimum voltage value that can be estimated based on its SOC.

[0106] If the voltage of a particular online battery reaches the target voltage (Yes in S520), the battery control device can check whether the battery is the last online battery (S830).

[0107] If the battery that has reached the target voltage is not the last battery online (No in S830), the battery control device can disconnect the battery from the DC link and switch it to the offline state (S840).

[0108] Thereafter, the battery control device can determine whether the SOC of the battery system is greater than or equal to a set value (S850).

[0109] Specifically, the battery control device can calculate the SOC of the battery system based on the SOC of each online battery currently connected to the DC link.

[0110] In an embodiment, the SOC of the battery system can be calculated as an average of the SOCs of the respective online batteries.

[0111] In another embodiment, the SOC of the battery system can be calculated according to the following equation.

[0112] [Equation 1]

[0113] Here, SOCmaxis the maximum value among the battery SOC values, and SOCminis the minimum value among the battery SOC values. max min

[0114] For example, if the SOCs of five racks are 100%, 99%, 99.5%, 98%, and 99.5%, respectively, the SOC of the battery system can be calculated as 99.2% according to Equation 1.

[0115] Thereafter, the battery control device can determine whether the calculated SOC of the battery system is greater than or equal to a set value (e.g., 98%).

[0116] If the SOC of the battery system is greater than or equal to the set value (Yes in S850), the battery control device can adjust the charging current flowing in the DC link to attenuate by a predetermined size (S860).

[0117] In an 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 the DC link, and control the charging and discharging power of the battery. For example, the battery control device can transmit a command for adjusting the charging power limit value to be attenuated to a power conversion system (PCS) of the battery system. Here, the PCS can reset the predetermined charging power limit value to a value of a low predetermined size (e.g., 0.05 CP), so that the charging current flowing in the DC link is attenuated.

[0118] ​​In another embodiment, the battery control device can transmit the attenuation-adjusted charging current value or the charging power value to a power control apparatus connected to the DC link, and control charging and discharging power of the battery. For example, the battery control device can transmit the attenuation-adjusted charging power limit value (e.g., 0.05 CP) to a power conversion system (PCS) of the battery system. Here, the PCS can reset the predetermined charging power limit value to the value received from the battery control device, thereby attenuating the charging current flowing in the DC link.

[0119] If the SOC of the battery system is less than the set value (NO in S850), the battery control device can monitor the voltage of the online battery without attenuation adjustment of the charging current (S810).

[0120] If the battery that has reached the target voltage is the last online battery (YES in S830), the battery control device can select one or more target batteries within a set range of the voltage of the last online battery from among the offline batteries that have been disconnected from the DC link while the last online battery is connected to the DC link (S870).

[0121] Thereafter, the battery control device 300 can reconnect the one or more selected target batteries to the DC link to switch them to the online state (S880).

[0122] In other words, the battery control device can monitor the SOC of the online battery during the process in which the online battery that has reached the target voltage is sequentially switched to the offline state. Here, when the online battery approaches a fully charged state, the battery control device can control the charging current to be attenuated, thereby minimizing an increase in internal resistance (IR) of the online battery and minimizing a voltage drop of the online battery due to charging. Accordingly, when all the batteries are fully charged and connected in parallel, a voltage deviation between the batteries can be minimized.

[0123] Figure 9 is an operation flowchart of a battery control method according to another embodiment of the present application.

[0124] The battery control device can monitor the voltage of each online battery during the charging process of the online battery (S910).

[0125] The battery control device can detect one or more batteries that have reached a predetermined target voltage among the online batteries (S920). Here, the target voltage can be predetermined as a minimum voltage value according to which the SOC can be estimated.

[0126] If the voltage of a specific online battery reaches the target voltage (YES in S920), the battery control device can correct the SOC of the battery (S925).

[0127] Thereafter, the battery control device can check whether the battery is the last online battery (S930).

[0128] If the battery that has reached the target voltage is not the last online battery (NO in S930), the battery control device can disconnect the battery from the DC link and switch it to an offline state (S940).

[0129] Thereafter, the battery control device can determine whether the SOC of the battery system is greater than or equal to a determined value (S950). Here, the battery control device 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 device can calculate the SOC of the battery system according to Equation 1 above.

[0130] If the SOC of the battery system is greater than or equal to the determined value (YES in S950), the battery control device can adjust the charging current flowing in the DC link to decay by a predetermined amount (S960).

[0131] If the SOC of the battery system is less than the determined value (NO in S950), the battery control device can monitor the voltage of the online battery without the decay adjustment of the charging current (S910).

[0132] If the battery that has reached the target voltage is the last online battery (YES in S930), the battery control device can compensate for the SOC of the last online battery while the last online battery is still connected to the DC link (S935).

[0133] The battery control device can select one or more target batteries, among offline batteries disconnected from the DC link, whose voltage difference from the last online battery is within a set range, and switch the selected target batteries to an online state (S970). In other words, the target battery can be a battery, among offline batteries charged to the target voltage and having completed SOC correction, whose voltage difference from the last online battery is within a set range.

[0134] Thereafter, the battery control device can check whether there is an offline battery that is not connected to the DC link (S980). That is, the battery control device can check whether there is an offline battery that is charged to the target voltage and has completed SOC correction, but whose voltage difference from the last online battery exceeds the set range.

[0135] If there is an offline battery (YES in S980), the battery control device can select one or more additional target batteries during a process of discharging at least one battery currently in an online state (S990), and sequentially switch the selected target batteries to an online state (S970).

[0136] In other words, when all of the batteries are fully charged and the SOC compensation is completed, but there is a voltage difference between the batteries, the battery control device can preferentially switch the battery within the set voltage range to the online state based on the voltage of the battery that was most recently fully charged. Thereafter, when the voltage of the online battery reaches the voltage of a specific offline battery during discharging of the online battery, the battery control device can switch the specific offline battery to the online state.

[0137] Figure 10 is a reference diagram for explaining a battery control method according to another embodiment of the present application.

[0138] Hereinafter, referring to Figure 10 , a battery control method according to another embodiment of the present application will be explained using a battery system including four battery racks connected in parallel as an example.

[0139] While the racks are charged in the online state, the battery control device can monitor the voltage of each of the racks (rack #1 to rack #4).

[0140] The battery control device can correct the SOC of the online rack that has reached the target voltage until only one online battery remains, and can switch the rack that completed the SOC correction to the offline state. For example, as Figure 10 shown, the remaining racks (rack #1, rack #2, rack #4) except for rack #3 can be sequentially switched to the offline state.

[0141] Then, at time t5, if the voltage of rack #3 reaches the target voltage, the battery control device can compensate for the SOC of rack #3 while rack #3 is connected to the DC link, and select a target rack whose voltage difference from rack #3 is within a set voltage range (for example, 0.2V). If rack #4 is selected as the target rack, rack #4 can be reconnected to the DC link at time t5 and switched to the online state, as Figure 10 shown.

[0142] Thereafter, the battery control device can select additional target racks while the online racks (rack #3, rack #4) are discharging, 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, rack #4) and rack #2 enters the set range, the battery control device can switch rack #2 to the online state. In addition, at time t7, if the voltage difference between the online racks (rack #2, rack #3, rack #4) and rack #1 falls within the set range, the battery control device can bring rack #1 online.

[0143] Figure 11 is a block diagram of a battery control device according to an embodiment of the present application.

[0144] The battery control device 1100 according to an embodiment of the present application can be located in a battery system and linked with a battery management device of each battery. For example, the battery control device 1100 can correspond to a battery system controller (BSC), an energy management system (EMS), or a power management system (PMS), or can be implemented by being included in any one of them.

[0145] The battery control device 1100 can include at least one processor 1110, a memory 1120 storing at least one instruction executed by the processor, and a transceiver 1130 connected to a network and performing communication.

[0146] Here, the at least one instruction can include an instruction to monitor a voltage of each of the batteries while the batteries are connected in parallel to a direct current (DC) link and are charged, an instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link, and an instruction to reconnect one or more batteries, among the at least one battery disconnected from the DC link, having a voltage difference from a last battery connected to the DC link within a set range to the DC link when the last battery reaches the target voltage.

[0147] The instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link can include an instruction to transmit a switch control signal for switching a switch connecting the battery and the DC link to an off state to a battery management device of the at least one battery that has reached the predetermined target voltage.

[0148] The instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link can include an instruction to correct a state of charge (SOC) of the at least one battery that has reached the predetermined target voltage and disconnect the at least one battery from the DC link.

[0149] The instruction to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link can include an instruction to correct an SOC of a last battery connected to the DC link while the last battery is connected to the DC link when the last battery reaches a target voltage.

[0150] The instruction to reconnect one or more batteries to the DC link can include an instruction to reconnect at least one battery, among the at least one battery disconnected from the DC link, having a voltage difference from a last battery connected to the DC link within a set range and completing an SOC correction to the DC link.

[0151] The instruction to reconnect one or more of the batteries to the DC link can include an instruction to sequentially reconnect one or more of the at least one battery, among the at least one battery not reconnected to the DC link, having a voltage difference from the at least one battery connected to the DC link falling within a set range, to the DC link during a process of discharging the at least one battery connected to the DC link.

[0152] The instruction to sequentially disconnect the at least one battery having reached the predetermined target voltage from the DC link can include an instruction to calculate an SOC of the battery system based on an SOC of the at least one battery connected to the DC link; and an instruction to adjust a charging current of the at least one battery connected to the DC link by a predetermined amount if the SOC of the battery system is equal to or greater than a determined SOC.

[0153] The battery control apparatus 1100 according to the embodiment of the present application can further include an input interface device 1140, an output interface device 1150, a storage device 1160, etc. The respective components included in the battery control apparatus 1100 can be connected by a bus 1170 and can communicate with each other.

[0154] Here, the processor 1110 can mean a central processing unit (CPU), a graphic processing unit (GPU), or a dedicated processor on which a method according to an embodiment of the present application is executed. The memory (or storage unit) can include at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory can include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0155] The operations of the method according to the embodiment of the present application can be implemented as a computer readable program or code on a computer readable recording medium. The computer readable recording medium includes all types of recording devices in which data readable by a computer system are stored. In addition, the computer readable recording medium can be distributed in a distributed manner among network connected computer systems to store and execute the computer readable program or code.

[0156] Although some aspects of the present application have been described in the context of an apparatus, it is clear that separate aspects of the present application also can be carried out according to a corresponding method, with corresponding actions carried out by one or more of the elements of the apparatus. Similarly, aspects described in the context of a method can also be carried out by means of an apparatus having one or more of the corresponding features of the method. Some or all of the method steps can be executed by (or using) a hardware apparatus, like for example, a microprocessor, a programmable computer or electronic circuit. In some embodiments, one or more of the most important method steps can be executed by such an apparatus.

[0157] In the foregoing, the present application has been described with reference to exemplary embodiments thereof. It will, however, be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the application as set forth in the appended claims.

Claims

1. A battery control device located in a battery system, the battery system comprising a plurality of batteries, the device comprising: At least one processor; as well as A memory configured to store at least one instruction executed by the at least one processor; Wherein, the at least one instruction includes: Instructions to monitor the voltage of each battery while the batteries are connected in parallel to a DC link and being charged; Commands to sequentially disconnect at least one battery that has reached a predetermined target voltage from the DC link; and When the last battery connected to the DC link reaches the target voltage, an instruction is given to reconnect one or more batteries from at least one battery disconnected from the DC link that have a voltage difference with the last battery within a set range to the DC link.

2. The apparatus according to claim 1, wherein, The instruction to sequentially disconnect at least one battery that has reached the predetermined target voltage from the DC link includes: A switch control signal for switching the switch connecting the battery and the DC link to the off state is sent to the battery management device of the at least one battery that has reached the predetermined target voltage.

3. The apparatus according to claim 1, wherein, The instruction to sequentially disconnect at least one battery that has reached the predetermined target voltage from the DC link includes: The instruction to correct the state of charge (SOC) of the at least one battery that has reached the predetermined target voltage and to disconnect the at least one battery from the DC link.

4. The apparatus according to claim 1, wherein, The instruction to sequentially disconnect at least one battery that has reached the predetermined target voltage from the DC link includes: When the last battery connected to the DC link reaches the target voltage, the instruction to correct the SOC of the last battery is given while the last battery is connected to the DC link.

5. The apparatus according to claim 4, wherein, Instructions for reconnecting one or more batteries to the DC link include: An instruction to reconnect at least one of the at least one batteries that has been disconnected from the DC link, whose voltage difference with the last battery is within the set range, and whose SOC correction has been completed, to the DC link.

6. The apparatus according to claim 1, wherein, Instructions for reconnecting one or more batteries to the DC link include: During the discharge process of at least one battery connected to the DC link, an instruction is given to sequentially reconnect one or more batteries that are not reconnected to the DC link and whose voltage difference with the at least one battery connected to the DC link falls within a set range to the DC link.

7. The apparatus according to claim 1, wherein, The instruction to sequentially disconnect at least one battery that has reached the predetermined target voltage from the DC link includes: Instructions for calculating the SOC of the battery system based on the SOC of at least one battery connected to the DC link; and If the SOC of the battery system is equal to or greater than a determined SOC, then the charging current of the at least one battery connected to the DC link is adjusted to a predetermined amount of attenuation.

8. A battery control method executed by a battery control device located in a battery system, the battery system comprising a plurality of batteries, the method comprising: The voltage of each cell in the battery is monitored while the battery is connected in parallel to a DC link and being charged. Sequentially disconnect at least one battery that has reached the predetermined target voltage from the DC link; and When the last battery connected to the DC link reaches the target voltage, one or more batteries that have been disconnected from the DC link and whose voltage difference with the last battery is within a set range are reconnected to the DC link.

9. The method according to claim 8, wherein, Sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link includes: A switch control signal for switching the switch connecting the battery and the DC link to the off state is sent to the battery management device of the at least one battery that has reached the predetermined target voltage.

10. The method according to claim 8, wherein, Sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link includes: Correct the state of charge (SOC) of the at least one battery that has reached the predetermined target voltage and disconnect the at least one battery from the DC link.

11. The method according to claim 8, wherein, Sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link includes: When the last battery connected to the DC link reaches the target voltage, the SOC of the last battery is corrected while the last battery is connected to the DC link.

12. The method according to claim 11, wherein, Reconnecting one or more batteries to the DC link includes: At least one battery that has been disconnected from the DC link, whose voltage difference with the last battery is within the set range, and whose SOC correction has been completed, is reconnected to the DC link.

13. The method according to claim 8, wherein, Reconnecting one or more batteries to the DC link includes: During the discharge process of at least one battery connected to the DC link, one or more batteries that are not reconnected to the DC link and whose voltage difference with the at least one battery connected to the DC link is within a set range are sequentially reconnected to the DC link.

14. The method according to claim 8, wherein, Sequentially disconnecting at least one battery that has reached a predetermined target voltage from the DC link includes: The SOC of the battery system is calculated based on the SOC of at least one battery connected to the DC link; and If the SOC of the battery system is equal to or greater than a determined SOC, the charging current of the at least one battery connected to the DC link is adjusted to decrease by a predetermined amount.

Images