Battery system and battery balancing method thereof

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 a charging characteristic curve. [Background technology]

[0003] Secondary batteries are batteries that can be reused by charging after discharging, 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 Energy Storage Systems (ESS) for smart grids.

[0004] Secondary batteries are applied to a system in the form of an assembly such as a battery module in which a number of battery cells are connected in series and parallel, or a battery pack in which battery modules are connected in series and parallel, depending on the requirements of the system. In the case of medium- to large-sized devices such as electric vehicles, a high-capacity battery system in which a number of battery packs are connected in parallel may be applied to meet the capacity requirements of the device.

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

[0006] In recent years, lithium iron phosphate (LiFePO4)-based compounds have been used as the positive electrode active material of lithium secondary batteries. Lithium iron phosphate (LFP) batteries, which use lithium iron phosphate as the positive electrode active material, are superior in terms of thermal stability and cost-effectiveness compared to other batteries. However, LFP batteries have a problem in that they exhibit flat characteristics with a voltage plateau in the charging characteristic curve (the relationship curve between open circuit voltage and SOC), and the SOC (State Of Charge) cannot be accurately estimated in the plateau.

[0007] In order to eliminate imbalances between battery cells during the operation of a battery system, cell balancing control based on an estimated SOC is essential. 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 PRESENT EMBODIMENT 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 for performing such a battery balancing method. [Means for solving the problem]

[0012] To achieve the above objective, 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 constant power rate (CP-rate) or a current rate (C-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 identified 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 when 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 per unit change in the SOC is equal to or greater than a preset reference value.

[0021] The threshold SOC may be defined as the SOC when 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 multiple battery cells, and if it is determined that balancing is necessary, it can perform a predetermined control operation for balancing the multiple battery cells.

[0023] To achieve another object, a battery balancing method according to one embodiment of the present invention is a battery balancing method by a battery management device in conjunction with a battery assembly including a plurality of battery cells, and may include a step of confirming a charging 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 charging 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 a step of 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 a step of checking a voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and a step of 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 a step of checking a voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and a step of 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 per unit change in the SOC is equal to or greater than a preset reference value.

[0031] The threshold SOC may be defined as the SOC when 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 confirm 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 multiple battery cells based on the confirmed charging rate.

[0035] The instruction to check the charging rate of the battery assembly may include an instruction to check a Constant Power-rate (CP-rate) or a Current-rate (C-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 instructions for determining whether to initiate the balancing mode may include an instruction to check a voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and an instruction to initiate 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 for determining whether balancing is necessary based on status information regarding the plurality of battery cells if the balancing mode is initiated, and an instruction for performing a predetermined control operation for balancing the plurality of battery cells if it is determined that balancing is necessary. Effect of the Invention

[0040] According to the above-described embodiment of the present invention, when balancing is performed on a battery having flat characteristics, balancing control can be performed in 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 the conventional technology in which balancing can be performed by switching to the balancing mode only in a resting state, it is possible to switch to the balancing mode and perform balancing control even in a charging state. [Brief description of the drawings]

[0042] [Figure 1] The charging characteristic curve of an LFP battery is shown. [Diagram 2] FIG. 1 is a block diagram illustrating a battery system according to the present invention. [Diagram 3] FIG. 2 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; [Diagram 5] 4 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. 4 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 PREFERRED EMBODIMENTS

[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 includes all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. Similar reference numerals are used for similar components while describing each drawing.

[0044] Terms such as first, second, A, B, etc. 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 named a second component, and similarly, a second component may be named a first component, without departing from the scope of the invention. The term "and / or" includes a combination of multiple associated listed items or any of multiple associated listed items.

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

[0046] The terms used in this application are merely used to describe certain embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and are not intended 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 the present invention belongs. 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 a minimum single structure that electrically connects modular units set by a battery manufacturer and can be monitored and controlled through a BMS (Battery Management System), and may be composed of multiple battery modules and one BPU or protection device.

[0051] A battery bank can refer to a large-scale collection of battery rack systems that are made up of multiple battery racks connected in parallel. The battery bank BMS can monitor and control the rack BMS (RBMS) for each battery rack.

[0052] The battery assembly means an assembly including a plurality of electrically connected battery cells and applied to a specific system or device to function as a power supply source. Here, the battery assembly may mean 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 set capacity [Ah] of a battery set by the battery manufacturer at the time of development.

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

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

[0057] In order to eliminate imbalance between battery cells during the operation of the battery system, the battery management system may compare the SOCs of the battery cells to determine an imbalance state, and perform balancing control if the imbalance state exceeds a predetermined threshold level. Here, in order to determine an imbalance state between battery cells, a method of measuring an open circuit voltage value of the battery and estimating the SOC of the battery based on the measured open circuit voltage value is commonly used.

[0058] 1, the charging characteristic curve of an LFP battery has a voltage plateau in an SOC range of about 10% to about 90%. In the case of an LFP battery having such a plateau characteristic, since it is difficult to accurately estimate the SOC in the plateau range, balancing control is performed only in non-plateau ranges (e.g., ranges where the SOC is 90% or more or ranges where the SOC is 10% or less). In other words, a battery system using an LFP battery can perform balancing control only 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 performing balancing control in a wider SOC range than the conventional technology, and a battery system performing such balancing control.

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

[0061] FIG. 2 is a block diagram for explaining 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 number of battery cells 10 may be electrically connected to each other and configured into 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 these. That is, the battery cell according to the present invention may correspond to a battery having at least a partial voltage plateau in the charging characteristic curve.

[0065] The battery management device 200 can collect status information on 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 device 200 can control charging and discharging of the battery cells, diagnose whether or not the battery cells are faulty, 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 in an energy storage system (ESS), but the scope of the present invention is not limited thereto. That is, the battery system according to the embodiment of the present invention may be applied to various devices such as an electric vehicle.

[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 a charging mode (S310), the battery management device 200 can check the charging rate of the battery assembly 100 (S320). 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.

[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 state 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 may determine whether a predetermined balancing mode start condition is satisfied 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 a charging rate.

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

[0075] For example, when the battery assembly is being charged at 0.10 CP, the battery management device 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 decide to start the balancing mode.

[0076] As another example, when the battery assembly is being charged at 0.50C, the battery management unit 200 can check 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), 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, when the balancing mode start condition is satisfied and the balancing mode is started, the battery management unit 200 may collect state information (e.g., voltage value or SOC) regarding a plurality of battery cells. Thereafter, the battery management unit 200 may determine whether a predetermined imbalance condition is satisfied based on the collected state information, and may determine whether balancing is necessary. For example, the imbalance condition may be defined as a state in which a difference between a minimum value and a maximum value among state values ​​(voltage value or SOC) of the battery cells is equal to or greater than a predetermined threshold value. When 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 an imbalance state between the battery cells. For example, the battery management unit 200 may control a cell balancing circuit to reduce a voltage variation or SOC variation 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 the embodiment of the present invention may be defined as a lower value as the charging rate of the battery assembly increases, and the threshold voltage value according to the 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 a charging characteristic curve derived by carrying out a pre-charging test at different charging rates for a battery assembly using an LFP battery. In the graph of Figure 4, the horizontal axis shows the SOC, and the vertical axis shows the voltage value of the battery assembly measured during the charging process.

[0083] 4, it can be seen that the lower the charge rate, the wider the SOC range in which a plateau appears, but the higher the charge rate, the narrower the SOC range in which a plateau appears. This is because when charging is performed at a high charge rate, the voltage due to the current and resistance has a large 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 even in a part of the flat region (e.g., the region where the SOC is 70-90%) 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, it is possible to estimate the SOC with high accuracy even in a relatively low SOC region, and even if the balancing mode is switched to in a relatively low SOC region, accurate balancing control can be performed.

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

[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 96, which is a threshold SOC 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 if the SOC of the battery assembly reaches 86, which is a lower value than 96, which is a threshold SOC value defined corresponding to 0.50 CP.

[0087] As another example, when the battery assembly is being charged at 0.05 CP, the balancing mode may be initiated if the voltage value of the battery assembly reaches 3.3877V (a voltage value corresponding to the threshold SOC) which is a threshold voltage value defined corresponding to 0.05 CP, whereas when the battery assembly is being charged at 0.50 CP, the balancing mode may be initiated if the voltage value of the battery assembly reaches 3.46V (a 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 is a voltage-SOC correspondence table derived by changing the charge rate and proceeding with pre-charging for a battery assembly using an LFP battery. 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 value may be defined as a voltage value when 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 Fig. 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., a minimum voltage value that may be determined by a voltage measuring device). That is, 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 start the battery balancing mode.

[0092] In an embodiment, the threshold SOC may be defined as an SOC value when the change in voltage value per unit change in SOC is equal to or greater than a preset 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 may be 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 may be 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 may be defined as 3.46 V and the threshold SOC as 86.

[0094] Meanwhile, the threshold voltage value or threshold SOC for the charge rate not performed in the pre-charge test process may be estimated and defined based on other pre-defined values. For example, as shown in FIG 5, if only pre-tests are performed with 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) and defined 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 when 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 of S640), the battery management unit 200 can determine to start a balancing mode (S650).

[0101] When the balancing mode is started, the battery management unit 200 may determine whether a predetermined imbalance condition is satisfied based on state information on a plurality of battery cells, and determine 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 it is determined that the imbalance condition is satisfied and balancing is necessary (Y of S660), the battery management unit 200 may perform a predetermined balancing control operation (S670). Here, the balancing control operation may include an operation of controlling a balancing circuit provided in the battery system to reduce the imbalance state 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 can 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 charging 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 an 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 a balancing mode (S750).

[0109] When the balancing mode is started, the battery management unit 200 may determine whether a predetermined imbalance condition is satisfied based on state information on a plurality of battery cells, and determine 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 required (Y of 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] The battery management device 800 according to the 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 for storing at least one instruction to be executed by the processor, and a transceiver 830 for communicating with a network.

[0113] The at least one instruction may include an instruction to, in a charging mode of the battery assembly, confirm a charging rate 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 charging rate.

[0114] The instruction to check the charging rate of the battery assembly may include an instruction to check a Constant Power-rate (CP-rate) or a Current-rate (C-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 instructions for determining whether to initiate the balancing mode may include an instruction to check a voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and an instruction to initiate 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 for determining whether balancing is necessary based on status information regarding the plurality of battery cells if the balancing mode is initiated, and an instruction for performing 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. Each component included in the battery management device 800 may be connected 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 operation of the method according to the embodiment of the present invention can be embodied as a computer readable program or code in a computer readable recording medium. The computer readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. In addition, the computer readable recording medium may be distributed to 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 it may also be presented in terms of a corresponding method, where a block or apparatus corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may be presented 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 with reference to preferred embodiments thereof, those skilled in the art will understand that various modifications and variations of the present invention can be made without departing from the spirit and scope of the present invention as set forth in the following claims. [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 regarding the battery assembly and manages and controls the battery assembly based on the collected status information; The battery management device includes: confirming a charging rate of the battery assembly in a charging mode of the battery assembly, and determining whether to start a balancing mode for balancing the plurality of battery cells based on the confirmed charging rate. Battery system.

2. The battery management device includes: When the battery assembly is switched to a charging mode, a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly is confirmed. The battery system according to claim 1 .

3. The battery management device includes: determining whether to initiate the balancing mode based on whether a pre-recorded threshold voltage value or threshold SOC corresponding to the determined charge rate has been reached; The battery system according to claim 1 .

4. The battery management device includes: checking a voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly, and starting the balancing mode when the voltage value reaches the threshold voltage value; The battery system according to claim 3 .

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

6. The threshold SOC is: The higher the charging rate of the battery assembly, the lower the charging rate is defined as the charging rate. The battery system according to claim 3 .

7. The threshold voltage value or threshold SOC is: It is 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; The battery system according to claim 3 .

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

9. 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 7 .

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

11. 1. A method of battery balancing using a battery management device in conjunction with a battery assembly including a plurality of battery cells, comprising: checking a charging rate of the battery assembly in a charging mode of the battery assembly; and determining whether to initiate a balancing mode for balancing the plurality of battery cells based on the confirmed charging rate; Battery balancing methods.

12. The step of checking the charging rate of the battery assembly includes: When the charging mode of the battery assembly is switched to, a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly is confirmed.

12. The method of claim 11.

13. The step of determining whether to initiate a balancing mode includes: determining whether to initiate the balancing mode based on whether a pre-recorded threshold voltage value or threshold SOC corresponding to the determined charge rate has been reached; 12. The method of claim 11.

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

14. The method of claim 13.

15. The step of determining whether to initiate a balancing mode includes: checking a voltage value of the battery assembly at predetermined time intervals during the charging process of the battery assembly; and starting the balancing mode when an SOC calculated based on the voltage value reaches the threshold SOC; 14. The method of claim 13.

16. The threshold SOC is: The higher the charging rate of the battery assembly, the lower the charging rate is defined as the charging rate.

14. The method of claim 13.

17. The threshold voltage value or threshold SOC is: The voltage-SOC curve or the voltage-SOC table is 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.

14. The method of claim 13.

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

20. The method of claim 17.

19. 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.

20. The method of claim 17.

20. When the balancing mode is started, determining whether balancing is required based on status information regarding 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 method of claim 11.

21. 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 the at least one processor; The at least one instruction: instructions for checking a charging rate of the battery assembly in a charging mode of the battery assembly; and determining whether to initiate a balancing mode for balancing the plurality of battery cells based on the confirmed charge rate; Battery management device.

22. The instructions for checking the charge rate of the battery assembly include: When the battery assembly is switched to a charging mode, the instruction includes an instruction to confirm a CP-rate (Constant Power-rate) or a C-rate (Current-rate) for charging the battery assembly. The battery management device of claim 21.

23. The instruction for determining whether to enter the balancing mode includes: determining whether to initiate the balancing mode based on whether a prerecorded threshold voltage value or threshold SOC corresponding to the determined charge rate has been reached; The battery management device of claim 21.

24. The instruction for determining whether to enter the balancing mode includes: an instruction to check a voltage value of the battery assembly at predetermined time intervals during a 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 of claim 23.

25. The instruction for determining whether to enter the balancing mode includes: an instruction to check a voltage value of the battery assembly at predetermined time intervals during a charging process of the battery assembly; and and an instruction to start the balancing mode if an SOC calculated based on the voltage value reaches the threshold SOC. The battery management device of claim 23.

26. The at least one instruction: When the balancing mode is started, instructions for determining whether balancing is required based on status information regarding the plurality of battery cells; and and if balancing is determined to be necessary, instructions for performing a predetermined control action for balancing the plurality of battery cells. The battery management device of claim 21.

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