Battery system and battery balancing method

Abstract

A battery system according to one embodiment of the present invention may include a battery assembly including a plurality of battery cells, and a battery management device that collects status information regarding the battery assembly and manages and controls the battery assembly based on the collected status information. Here, the battery management device can check the charging rate of the battery assembly in the charging mode of the battery assembly, and determine whether to start a balancing mode for balancing the multiple battery cells based on the checked charging rate.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0164439, filed with the Korean Intellectual Property Office on November 30, 2022, and all of the contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery system and a battery balancing method thereof, and more particularly to a battery system and a battery balancing method thereof for balancing batteries having a voltage plateau in their charging characteristic curves. [Background technology]

[0003] Secondary batteries are batteries that can be reused by recharging after discharge and can be used as energy sources for small devices such as mobile phones, tablet PCs, and vacuum cleaners, as well as medium- to large-sized devices such as automobiles and smart grid ESS (Energy Storage Systems).

[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 or parallel, or battery packs in which battery modules are connected in series or parallel, depending on the requirements of the system. In the case of medium to large devices such as electric vehicles, a high-capacity battery system in which multiple battery packs are connected in parallel may be applied to meet the required capacity of the device.

[0005] Carbon materials are mainly used as the negative electrode active material for lithium secondary batteries, and lithium-containing cobalt oxide (LiCoO2) is mainly used as the positive electrode active material, although the use of lithium-containing manganese oxide (LiMnO2, LiMn2O4, etc.) and lithium-containing nickel oxide (LiNiO2) is also being considered.

[0006] In recent years, lithium iron phosphate (LiFePO4)-based compounds have been used as the positive electrode active material in lithium secondary batteries. Lithium iron phosphate (LFP) batteries, which use lithium iron phosphate as the positive electrode active material, offer superior thermal stability and cost-effectiveness compared to other batteries. However, LFP batteries exhibit a flat characteristic with a voltage plateau in their charging characteristic curve (the relationship between open-circuit voltage and SOC), which makes it difficult to accurately estimate the State of Charge (SOC) during this plateau.

[0007] During the operation of a battery system, cell balancing control based on an estimated SOC is essential to resolve imbalances between battery cells. However, in the case of LFP batteries, it is difficult to accurately estimate the SOC in flat sections, so cell balancing control is only performed in non-flat sections (e.g., sections where the SOC is 90% or higher, or sections where the SOC is 10% or lower).

[0008] Therefore, a suitable control technique is needed for balancing batteries that have a voltage plateau in their charging characteristic curve, such as LFP batteries. Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a battery system for balancing batteries having a voltage plateau section in the charging characteristic curve.

[0010] Another object of the present invention to solve the above problems is to provide a battery balancing method for such a battery system.

[0011] Another object of the present invention to solve the above problems is to provide a battery management device that performs such a battery balancing method. [Means for solving the problem]

[0012] To achieve the above object, a battery system according to one embodiment of the present invention can include a battery assembly including a plurality of battery cells, and a battery management device that collects status information regarding the battery assembly and manages and controls the battery assembly based on the collected status information.

[0013] Here, the battery management device can check the charging rate of the battery assembly in the charging mode of the battery assembly, and determine whether to start a balancing mode for balancing the multiple battery cells based on the checked charging rate.

[0014] When the battery management unit is switched to a charging mode of the battery assembly, it can check a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly.

[0015] The battery management unit can determine whether to initiate a balancing mode based on whether a pre-recorded threshold voltage value or threshold SOC corresponding to the confirmed charge rate has been reached.

[0016] The battery management device may check the voltage value of the battery assembly at predetermined time intervals during charging of the battery assembly, and may start a balancing mode if the voltage value reaches a threshold voltage value.

[0017] The battery management device checks the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and can start a balancing mode when the SOC calculated based on the voltage value reaches a threshold SOC.

[0018] The threshold SOC may be defined as a value that is lower the higher the charge rate of the battery assembly.

[0019] The threshold voltage value or threshold SOC may be predefined based on a voltage-SOC correspondence curve or a voltage-SOC correspondence table derived during a pre-charging process according to the charging rate of the battery assembly.

[0020] The threshold voltage value may be defined as a voltage value at which the amount of change in the voltage value relative to a unit amount of change in the SOC is equal to or greater than a preset reference value.

[0021] The threshold SOC may be defined as the SOC at which the amount of change in voltage value per unit change in SOC is equal to or greater than a preset reference value.

[0022] When the balancing mode is initiated, the battery management device determines whether balancing is necessary based on status information regarding the plurality of battery cells, and if it determines that balancing is necessary, it can perform a predetermined control operation for balancing the plurality of battery cells.

[0023] To achieve another object, a battery balancing method according to one embodiment of the present invention is a battery balancing method using a battery management device that interfaces with a battery assembly including a plurality of battery cells, and can include a step of confirming a charge rate of the battery assembly in a charging mode of the battery assembly, and a step of determining whether to start a balancing mode for balancing the plurality of battery cells based on the confirmed charge rate.

[0024] The step of checking the charging rate of the battery assembly may include checking a CP-rate (Constant Power-rate) or C-rate (Current-rate) for charging the battery assembly when the battery assembly is switched to a charging mode.

[0025] The step of determining whether to initiate the balancing mode may include determining whether to initiate the balancing mode based on whether a pre-recorded threshold voltage value or threshold SOC corresponding to the identified charge rate has been reached.

[0026] The step of determining whether to start the balancing mode may include the steps of checking the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and starting the balancing mode if the voltage value reaches a threshold voltage value.

[0027] The step of determining whether to start the balancing mode may include the steps of checking the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and starting the balancing mode if the SOC calculated based on the voltage value reaches a threshold SOC.

[0028] The threshold SOC may be defined as a value that is lower the higher the charge rate of the battery assembly.

[0029] The threshold voltage value or threshold SOC may be predefined based on a voltage-SOC correspondence curve or a voltage-SOC correspondence table derived during a pre-charging process according to the charging rate of the battery assembly.

[0030] The threshold voltage value may be defined as a voltage value at which the amount of change in the voltage value relative to a unit amount of change in the SOC is equal to or greater than a preset reference value.

[0031] The threshold SOC may be defined as the SOC at which the amount of change in voltage value per unit change in SOC is equal to or greater than a preset reference value.

[0032] The battery balancing method may further include, if the balancing mode is initiated, determining whether balancing is necessary based on status information regarding the plurality of battery cells, and, if it is determined that balancing is necessary, performing a predetermined control operation for balancing the plurality of battery cells.

[0033] In order to achieve the above-mentioned yet another object, a battery management device according to one embodiment of the present invention is a battery management device that operates in conjunction with a battery assembly including a plurality of battery cells, and may include at least one processor and a memory that stores at least one instruction that is executed through the at least one processor.

[0034] Here, the at least one instruction may include an instruction to check a charging rate of the battery assembly in a charging mode of the battery assembly, and an instruction to determine whether to start a balancing mode for balancing the plurality of battery cells based on the checked charging rate.

[0035] The instruction to check the charging rate of the battery assembly may include an instruction to check the CP-rate (Constant Power-rate) or C-rate (Current-rate) for charging the battery assembly when the battery assembly is switched to a charging mode.

[0036] The instructions for determining whether to initiate the balancing mode may include instructions for determining whether to initiate the balancing mode based on whether a pre-recorded threshold voltage value or threshold SOC corresponding to the identified charge rate has been reached.

[0037] The instruction to determine whether to start the balancing mode may include an instruction to check the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and an instruction to start the balancing mode if the voltage value reaches a threshold voltage value.

[0038] The command to determine whether to start the balancing mode may include a command to check the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and a command to start the balancing mode if the SOC calculated based on the voltage value reaches a threshold SOC.

[0039] The at least one instruction may further include an instruction to determine whether balancing is necessary based on status information regarding the plurality of battery cells if the balancing mode is initiated, and an instruction to perform a predetermined control operation for balancing the plurality of battery cells if it is determined that balancing is necessary. [Effects of the Invention]

[0040] According to the above-described embodiments of the present invention, when balancing a battery having flat characteristics, balancing control can be performed over a wider SOC range than in the prior art.

[0041] Furthermore, according to the above-described embodiment of the present invention, when performing cell balancing on a battery having flat characteristics, unlike conventional technology in which balancing can be performed by switching to balancing mode only in a resting state, it is possible to switch to balancing mode and perform balancing control even in a charging state. [Brief explanation of the drawings]

[0042] [Figure 1] The charging characteristic curve of an LFP battery is shown. [Figure 2] 1 is a block diagram illustrating a battery system according to the present invention. [Figure 3] FIG. 1 is a flow diagram of a battery balancing method according to an embodiment of the present invention. [Figure 4] 1 is a reference diagram for explaining a battery balancing method according to an embodiment of the present invention; [Figure 5] 1 is a reference table for explaining a battery balancing method according to an embodiment of the present invention. [Figure 6] FIG. 2 is a flow diagram of a threshold voltage based battery balancing method according to an embodiment of the present invention. [Figure 7] FIG. 10 is a flow diagram of a threshold SOC based battery balancing method according to another embodiment of the present invention. [Figure 8] 1 is a block diagram of a battery management device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, it is understood that this is not intended to limit the present invention to the specific embodiments, but rather to include all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. Similar reference numerals are used to refer to similar components throughout the description of the various drawings.

[0044] Terms such as "first," "second," "A," and "B" may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be designated as a second component, and similarly, a second component may be designated as a first component, without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any one of multiple associated listed items.

[0045] When a component is referred to as being "coupled" or "connected" to another component, it is understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is referred to as being "directly coupled" or "directly connected" to another component, it is understood that there are no other components in between.

[0046] The terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and are understood not to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0047] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless expressly defined in this application.

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

[0049] A battery cell is the smallest unit that serves to store power, and a battery module refers to an assembly of a plurality of battery cells that are electrically connected together.

[0050] A battery pack or battery rack refers to a system with the smallest single structure that can be monitored and controlled through a BMS (Battery Management System) by electrically connecting module units set by a battery manufacturer, and may be composed of multiple battery modules and one BPU or protection device.

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

[0052] A battery assembly refers to an assembly including a plurality of electrically connected battery cells that is applied to a specific system or device and functions as a power supply source. Here, the battery assembly may refer to a battery module, a battery pack, a battery rack, a battery bank, or the like, but the scope of the present invention is not limited to these.

[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] Nominal Capacity (Nominal Capa.) can refer to the battery's set capacity [Ah] set by the battery manufacturer at the time of development.

[0055] Figure 1 shows the charging characteristic curve of an LFP battery.

[0056] More specifically, Figure 1 shows the charging characteristic curve of an LFP (Lithium Iron Phosphate) battery, which uses lithium iron phosphate as the positive electrode active material. The charging characteristic curve shows the relationship between the open circuit voltage (OCV) measured during the charging process of the battery and the SOC.

[0057] In order to resolve imbalances between battery cells during the operation of a battery system, a battery management system may compare the SOCs of the battery cells to determine an imbalance, and perform balancing control if the imbalance exceeds a predetermined threshold level. Here, a commonly used method for determining an imbalance between battery cells is to measure the open-circuit voltage of the battery and estimate the SOC of the battery based on the measured open-circuit voltage.

[0058] Referring to Figure 1, the charging characteristic curve of an LFP battery has a voltage plateau in the SOC range of approximately 10% to approximately 90%. For an LFP battery with such a plateau characteristic, it is difficult to accurately estimate the SOC in the plateau range, so balancing control is performed only in non-plateau ranges (e.g., SOC above 90% or SOC below 10%). In other words, a battery system using an LFP battery can only perform balancing control in a very limited SOC range, which limits the operational stability of the system.

[0059] The present invention has been devised to solve the problems of the conventional technology, and relates to a battery system capable of balancing control over a wider SOC range than the conventional technology, and a battery system for performing such control.

[0060] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0061] FIG. 2 is a block diagram illustrating the battery system according to the present invention.

[0062] Referring to FIG. 2, the battery system includes a battery assembly 100 including a plurality of battery cells 10 and a battery management device 200.

[0063] A plurality of battery cells 10 may be electrically connected to each other to form a battery assembly.

[0064] The battery cell 10 may be an LFP battery cell, but the scope of the present invention is not limited to this. That is, the battery cell according to the present invention may correspond to a battery having at least a partial voltage plateau in its charging characteristic curve.

[0065] The battery management unit 200 can collect status information about the plurality of battery cells 10 and perform a predetermined control operation based on the collected status information to manage and control the battery assembly 100. Here, the battery management unit 200 can control charging and discharging of the battery cells, diagnose whether or not there is a failure in the battery cells, and determine an imbalance state of the battery cells to perform balancing control.

[0066] The battery management device 200 may be embodied and included in a BMS located inside the battery system.

[0067] The battery system according to the embodiment of the present invention may be embodied as an energy storage system (ESS), but the scope of the present invention is not limited thereto. That is, the battery system according to the present invention may be applied to various devices such as electric vehicles.

[0068] FIG. 3 is a flow diagram of a battery balancing method according to an embodiment of the present invention.

[0069] When the battery system is switched to the charging mode (S310), the battery management device 200 can check the charging rate of the battery assembly 100 (S320). Here, the charging rate may refer to a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly 100.

[0070] The battery management device 200 can check the charging rate from a charging / discharging device (not shown) that charges the battery assembly 100, or can check the charging rate based on one or more status values ​​of a charging voltage value and a charging current value sensed through one or more voltage sensors and current sensors provided in the battery system.

[0071] The battery management unit 200 can determine whether a predetermined balancing mode start condition is met based on the confirmed charging rate (S330) and decide whether to start a balancing mode for balancing a plurality of battery cells.

[0072] If the balancing mode start condition is satisfied, the battery management unit 200 can start the balancing mode (S340).

[0073] The balancing mode start condition according to an embodiment of the present invention may be defined based on the charging rate.

[0074] In an embodiment, the balancing mode start condition may be defined as reaching a threshold voltage value or a threshold SOC stored corresponding to the charge rate.

[0075] For example, if the battery assembly is being charged at 0.10 CP, the battery management unit 200 checks the voltage value of the battery assembly at predetermined time intervals during the charging process, and if the voltage value of the battery assembly reaches a predefined threshold voltage value (e.g., 3.4009 V) corresponding to 0.10 CP (satisfying the balancing mode start condition), it can determine to start the balancing mode.

[0076] As another example, when a battery assembly is being charged at 0.50C, the battery management unit 200 checks the SOC of the battery assembly at predetermined time intervals during the charging process, and if the SOC of the battery assembly reaches a predefined threshold SOC (e.g., 86) corresponding to 0.50C (satisfying the balancing mode start condition), it can decide to start the balancing mode.

[0077] When the balancing mode is started, the battery management unit 200 determines whether balancing is necessary, and if balancing is necessary, can perform a predetermined control operation for balancing.

[0078] More specifically, if the balancing mode start condition is satisfied and the balancing mode is initiated, the battery management unit 200 may collect state information (e.g., voltage values ​​or SOC) about a plurality of battery cells. Then, the battery management unit 200 may determine whether a predetermined imbalance condition is satisfied based on the collected state information, thereby determining whether balancing is necessary. For example, the imbalance condition may be defined as a state in which the difference between the minimum and maximum state values ​​(voltage values ​​or SOC) of the battery cells is equal to or greater than a predetermined threshold. If the imbalance condition is satisfied and it is determined that balancing is necessary, the battery management unit 200 may perform a predetermined balancing control operation. Here, the balancing control operation may include an operation of controlling a balancing circuit provided in the battery system to reduce the imbalance between the battery cells. For example, the battery management unit 200 may control the cell balancing circuit to reduce voltage variations or SOC variations between the battery cells. Meanwhile, the balancing control method may be a known technique such as a passive balancing control method, and detailed description of the balancing method and balancing circuit is omitted since they are not essential components of the present invention.

[0079] FIG. 4 is a reference diagram for explaining the battery balancing method according to the embodiment of the present invention, and FIG. 5 is a reference table for explaining the battery balancing method according to the embodiment of the present invention.

[0080] The battery management unit 200 may determine whether to start the balancing mode by determining whether a predetermined balancing mode start condition is satisfied based on the charging rate of the battery assembly. Here, the balancing mode start condition may be defined as a state in which a threshold voltage value or a threshold SOC stored corresponding to the charging rate is reached.

[0081] The threshold SOC according to an embodiment of the present invention may be defined as a value that decreases as the charging rate of the battery assembly increases, and the threshold voltage according to an embodiment of the present invention may be defined as a voltage value corresponding to the threshold SOC on a charging characteristic curve.

[0082] Figure 4 shows charging characteristic curves derived from a pre-charge test conducted at different charging rates for a battery assembly using an LFP battery. In the graph of Figure 4, the horizontal axis represents the SOC, and the vertical axis represents the voltage of the battery assembly measured during the charging process.

[0083] 4, it can be seen that a plateau appears in a wider SOC range as the charge rate decreases, but a plateau appears in a narrower SOC range as the charge rate increases. This is because when charging proceeds at a high charge rate, the voltage due to current and resistance has a significant effect on the voltage profile during charging of the LFP battery.

[0084] As shown in Figure 4, the charging characteristic curve at a high charging rate (e.g., 0.50 CP) shows a slope in a certain region (e.g., the SOC range of 70-90%) of the flat region of the charging characteristic curve at a low charging rate (e.g., 0.05 CP). As a result, when charging at a high charging rate, SOC can be estimated with high accuracy even in a relatively low SOC range, and accurate balancing control can be performed even when switching to balancing mode in a relatively low SOC range.

[0085] Based on the above principle, the threshold SOC according to the embodiment of the present invention may be defined as a value that decreases as the charging rate of the battery assembly increases.

[0086] For example, when the battery assembly is being charged at 0.05 CP, the balancing mode may be initiated if the SOC of the battery assembly reaches a threshold SOC value of 96 defined corresponding to 0.05 CP. On the other hand, when the battery assembly is being charged at 0.50 CP, the balancing mode may be initiated if the SOC of the battery assembly reaches a threshold SOC value of 86 defined corresponding to 0.50 CP, which is lower than 96.

[0087] As another example, when the battery assembly is being charged at 0.05 CP, the balancing mode may be initiated when the voltage value of the battery assembly reaches 3.3877 V (the voltage value corresponding to the threshold SOC) which is a threshold voltage value defined corresponding to 0.05 CP. On the other hand, when the battery assembly is being charged at 0.50 CP, the balancing mode may be initiated when the voltage value of the battery assembly reaches 3.46 V (the voltage value corresponding to the threshold SOC of 86) which is a threshold voltage value defined corresponding to 0.50 CP.

[0088] In an embodiment, the threshold voltage value or threshold SOC may be predefined based on a voltage-SOC correspondence value, a voltage-SOC correspondence curve, or a voltage-SOC correspondence table derived during a pre-charging process according to the charging rate of the battery assembly.

[0089] FIG. 5 shows a voltage-SOC correspondence table derived by pre-charging a battery assembly using an LFP battery while changing the charge rate. FIGS. 5(A) to 5(D) show voltage-SOC correspondence tables for charge rates of 0.05, 0.10, 0.40, and 0.50 CP, respectively.

[0090] In an embodiment, the threshold voltage may be defined as a voltage value at which a change in voltage value per unit change in SOC is equal to or greater than a preset reference value, where the reference value may be set based on the measurement accuracy of a voltage measuring device included in the battery system.

[0091] For example, referring to Figure 5A, when the charging rate is 0.05 CP, the voltage difference gradually increases as the SOC increases by 1. Here, the threshold voltage value may be defined as 3.3877 V, which is the voltage value when the voltage difference is equal to or greater than a predetermined reference value of 0.03 V (e.g., the minimum voltage value that may be determined by a voltage measuring device). In other words, when the battery assembly transitions to a state where an imbalance state can be determined through the voltage measuring device, the battery management device may initiate a battery balancing mode.

[0092] In an embodiment, the threshold SOC may be defined as the SOC value when the change in voltage value per unit change in SOC is equal to or greater than a predetermined reference value. For example, referring to FIG. 5A, when the charging rate is 0.05 CP, the threshold SOC may be defined as 96, which is the SOC when the voltage difference is equal to or greater than a predetermined reference value (0.03 V).

[0093] In the same manner as above, when the charging rate is 0.10 CP (see FIG. 5(B)), the threshold voltage value is defined as 3.4009 V and the threshold SOC as 95; when the charging rate is 0.40 CP (see FIG. 5(C)), the threshold voltage value is defined as 3.4443 V and the threshold SOC as 88; and when the charging rate is 0.50 CP (see FIG. 5(D)), the threshold voltage value is defined as 3.46 V and the threshold SOC as 86.

[0094] Meanwhile, the threshold voltage or threshold SOC for a charge rate not subjected to a pre-test may be estimated based on other pre-defined values. For example, as shown in FIG. 5, if pre-tests are performed only at charge rates of 0.05, 0.10, 0.40, and 0.50 CP, the threshold SOC for 0.02 and 0.03 CP may be estimated (e.g., 93, 91) based on the correlation between the charge rates (0.05, 0.10, 0.40, 0.50) and the threshold SOC (96, 95, 88, 86).

[0095] FIG. 6 is a flow diagram of a threshold voltage based battery balancing method according to an embodiment of the present invention.

[0096] When the battery system is switched to the charging mode (S610), the battery management device 200 can check the charging rate of the battery assembly 100 (S620). Here, the charging rate can refer to a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly 100.

[0097] The battery management device 200 may check the voltage value of the battery assembly 100 at predetermined time intervals during the charging process of the battery assembly 100 (S630).

[0098] The battery management unit 200 may determine whether the voltage value of the battery assembly reaches a predefined threshold voltage value corresponding to the charging rate confirmed in S620 (S640).

[0099] Here, the threshold voltage value may be predefined based on a voltage-SOC correspondence value, a voltage-SOC correspondence curve, or a voltage-SOC correspondence table derived during a pre-charging process according to the charging rate of the battery assembly. In an embodiment, the threshold voltage value may be defined as a voltage value at which a change in voltage value per unit change in SOC is equal to or greater than a predefined reference value.

[0100] If the voltage value of the battery assembly reaches a predefined threshold voltage value (Y in S640), the battery management unit 200 can determine to start the balancing mode (S650).

[0101] When the balancing mode is initiated, the battery management unit 200 determines whether a predetermined imbalance condition is satisfied based on the state information of the plurality of battery cells, and determines whether balancing is necessary (S660). Here, the imbalance condition may be defined as a state in which the difference between the minimum and maximum state values ​​(voltage value or SOC) of the battery cells is equal to or greater than a predetermined threshold value.

[0102] If the imbalance condition is satisfied and balancing is required (Y in S660), the battery management unit 200 may perform a predetermined balancing control operation (S670). Here, the balancing control operation may include controlling a balancing circuit provided in the battery system to reduce the imbalance between the battery cells. For example, the battery management unit 200 may control the cell balancing circuit to reduce the voltage variation or SOC variation between the battery cells.

[0103] FIG. 7 is a flow diagram of a threshold SOC based battery balancing method according to another embodiment of the present invention.

[0104] When the battery system is switched to the charging mode (S710), the battery management device 200 can check the charging rate of the battery assembly 100 (S720). Here, the charging rate may refer to a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly 100.

[0105] The battery management device 200 may check the SOC of the battery assembly at predetermined time intervals (S730) during the charging process of the battery assembly 100. Here, the SOC of the assembly may correspond to a value estimated based on the voltage value of the battery assembly.

[0106] The battery management unit 200 may determine whether the SOC of the battery assembly reaches a predefined threshold SOC corresponding to the charge rate confirmed in S720 (S740).

[0107] Here, the threshold SOC may be predefined based on a voltage-SOC correspondence value, a voltage-SOC correspondence curve, or a voltage-SOC correspondence table derived during a pre-charging process according to the charging rate of the battery assembly. In an embodiment, the threshold SOC may be defined as the SOC when a change in voltage value per unit change in SOC is equal to or greater than a predefined reference value.

[0108] If the SOC of the battery assembly reaches a predefined threshold SOC (Y in S740), the battery management unit 200 can determine to start the balancing mode (S750).

[0109] When the balancing mode is initiated, the battery management unit 200 determines whether a predetermined imbalance condition is satisfied based on the state information of the plurality of battery cells, and determines whether balancing is necessary (S760). Here, the imbalance condition may be defined as a state in which the difference between the minimum and maximum state values ​​(voltage value or SOC) of the battery cells is equal to or greater than a predetermined threshold value.

[0110] If it is determined that the imbalance condition is satisfied and balancing is necessary (Y in S760), the battery management unit 200 can perform a predetermined balancing control operation (S770).

[0111] FIG. 8 is a block diagram of a battery management device according to an embodiment of the present invention.

[0112] A battery management device 800 according to an embodiment of the present invention may be located in a battery system and may operate in conjunction with a battery assembly including a plurality of battery cells. The battery management device 800 may include at least one processor 810, a memory 820 that stores at least one instruction to be executed by the processor, and a transceiver 830 that is connected to a network for communication.

[0113] The at least one instruction may include an instruction to confirm a charge rate of the battery assembly in a charging mode of the battery assembly, and an instruction to determine whether to initiate a balancing mode for balancing the plurality of battery cells based on the confirmed charge rate.

[0114] The instruction to check the charging rate of the battery assembly may include an instruction to check the CP-rate (Constant Power-rate) or C-rate (Current-rate) for charging the battery assembly when the battery assembly is switched to a charging mode.

[0115] The instructions for determining whether to initiate the balancing mode may include instructions for determining whether to initiate the balancing mode based on whether a pre-recorded threshold voltage value or threshold SOC corresponding to the identified charge rate has been reached.

[0116] The command to determine whether to start the balancing mode may include a command to check the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and a command to start the balancing mode if the voltage value reaches a threshold voltage value.

[0117] The command to determine whether to start the balancing mode may include a command to check the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and a command to start the balancing mode if the SOC calculated based on the voltage value reaches a threshold SOC.

[0118] The at least one instruction may further include an instruction to determine whether balancing is necessary based on status information regarding the plurality of battery cells if the balancing mode is initiated, and an instruction to perform a predetermined control operation for balancing the plurality of battery cells if it is determined that balancing is necessary.

[0119] The battery management device 800 may further include an input interface device 840, an output interface device 850, a storage device 860, etc. The components included in the battery management device 800 are connected to each other by a bus 870 to communicate with each other.

[0120] Here, the processor 810 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the method according to the embodiment of the present invention is performed. 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).

[0121] The operations of the method according to the embodiment of the present invention may be embodied as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium may include any type of storage device in which data that can be read by a computer system is stored. The computer-readable recording medium may also be distributed among computer systems connected via a network, so that the computer-readable program or code may be stored and executed in a distributed manner.

[0122] Some aspects of the invention have been described in the context of an apparatus, but they may also be described in terms of a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may be described in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0123] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and variations can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. [Explanation of symbols]

[0124] 10: Battery cell 100: Battery assembly 200, 800: Battery management device

Claims

1. a battery assembly including a plurality of battery cells; and a battery management device that collects status information about the battery assembly and manages and controls the battery assembly based on the collected status information; The battery management device In a charging mode of the battery assembly, confirming a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly; determining whether to start a balancing mode for balancing the plurality of battery cells based on whether a voltage value or a SOC of the battery assembly reaches a pre-recorded threshold voltage value or a pre-recorded threshold SOC corresponding to the confirmed CP-rate or C-rate; Battery system.

2. The battery management device During the charging of the battery assembly, a voltage value of the battery assembly is checked at predetermined time intervals, and when the voltage value reaches the threshold voltage value, the balancing mode is initiated. The battery system of claim 1.

3. The battery management device During the charging process of the battery assembly, a voltage value of the battery assembly is checked at predetermined time intervals, and when an SOC calculated based on the voltage value reaches the threshold SOC, the balancing mode is initiated. The battery system according to claim 1 .

4. The threshold SOC is: The higher the CP-rate or C-rate of the battery assembly, the lower the value is defined as; The battery system according to claim 1 .

5. The threshold voltage value or threshold SOC is: The voltage-SOC curve or the voltage-SOC table is predefined based on the voltage-SOC curve or the voltage-SOC table, which is derived during the pre-charging process of the battery assembly at the CP-rate or the C-rate. The battery system of claim 1.

6. The threshold voltage value is It is defined as the voltage value when the change in voltage value per unit change in SOC is equal to or greater than a preset reference value. The battery system according to claim 5 .

7. The threshold SOC is: It is defined as the SOC when the change in voltage value per unit change in SOC is equal to or greater than a preset reference value. The battery system according to claim 5 .

8. When the balancing mode is initiated, The battery management device determining whether balancing is necessary based on the state information regarding the plurality of battery cells, and if it is determined that balancing is necessary, performing a predetermined control operation for balancing the plurality of battery cells; The battery system according to claim 1 .

9. 1. A battery balancing method using a battery management device in conjunction with a battery assembly including a plurality of battery cells, comprising: In a charging mode of the battery assembly, determining a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly; and determining whether to initiate a balancing mode for balancing the plurality of battery cells based on whether a voltage value or a SOC of the battery assembly reaches a pre-recorded threshold voltage value or a threshold SOC corresponding to the confirmed CP-rate or C-rate; Battery balancing method.

10. The step of determining whether to initiate a balancing mode includes: checking a voltage value of the battery assembly at predetermined time intervals during charging of the battery assembly; and and initiating the balancing mode if the voltage value reaches the threshold voltage value.

10. The battery balancing method of claim 9.

11. The step of determining whether to initiate a balancing mode includes: checking a voltage value of the battery assembly at predetermined time intervals during charging of the battery assembly; and and starting the balancing mode when an SOC calculated based on the voltage value reaches the threshold SOC.

10. The battery balancing method of claim 9.

12. The threshold SOC is: The higher the CP-rate or C-rate of the battery assembly, the lower the value is defined as; 10. The battery balancing method of claim 9.

13. The threshold voltage value or threshold SOC is: The voltage-SOC curve or the voltage-SOC table is predefined based on the voltage-SOC curve or the voltage-SOC table, which is derived during the pre-charging process of the battery assembly at the CP-rate or C-rate.

10. The battery balancing method of claim 9.

14. The threshold voltage value is It is defined as the voltage value when the change in voltage value per unit change in SOC is equal to or greater than a preset reference value.

14. The battery balancing method of claim 13.

15. The threshold SOC is: It is defined as the SOC when the change in voltage value per unit change in SOC is equal to or greater than a preset reference value.

14. The battery balancing method of claim 13.

16. When the balancing mode is initiated, determining whether balancing is required based on status information about the plurality of battery cells; and If it is determined that balancing is necessary, performing a predetermined control action for balancing the plurality of battery cells.

12. The battery balancing method of claim 11.

17. 1. A battery management device for use with a battery assembly including a plurality of battery cells, comprising: at least one processor; and a memory for storing at least one instruction to be executed by said at least one processor; The at least one instruction: In a charging mode of the battery assembly, an instruction to confirm a CP-rate (Constant Power-rate) or C-rate (Current-rate) for charging the battery assembly; and and an instruction to determine whether to initiate a balancing mode for balancing the plurality of battery cells based on whether a voltage value or a SOC of the battery assembly reaches a pre-recorded threshold voltage value or a threshold SOC corresponding to the confirmed CP-rate or C-rate. Battery management device.

18. The instruction for determining whether to initiate the balancing mode includes: an instruction to check the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly; and and instructions for initiating the balancing mode if the voltage value reaches the threshold voltage value. The battery management device according to claim 17.

19. The instruction for determining whether to initiate the balancing mode includes: an instruction to check the voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly; and and a command to start the balancing mode when an SOC calculated based on the voltage value reaches the threshold SOC. The battery management device according to claim 17.

20. The at least one instruction: When the balancing mode is initiated, instructions for determining whether balancing is required based on status information about the plurality of battery cells; and and if it is determined that balancing is necessary, instructions for performing a predetermined control action for balancing the plurality of battery cells. The battery management device according to claim 17.

21. A computer program which, when executed by a processor of the battery management unit, causes the battery management unit to perform the battery balancing method of any one of claims 9 to 16.

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