Battery management device, battery pack, electric vehicle, and battery management method

Abstract

A battery management device, a battery pack, an electric vehicle, and a battery management method are provided. The battery management device according to one embodiment of the present invention is provided for a battery module including a plurality of battery cells, and includes: a state monitoring unit configured to acquire a plurality of cell state parameters indicating electrical states of the plurality of battery cells; a balancing processing unit configured to execute a balancing process, which is a procedure for selectively discharging or charging each of the plurality of battery cells, to suppress variations in the electrical states among the battery cells; and a control unit configured to control the balancing processing unit to execute the balancing process for at least one battery cell among the plurality of battery cells based on the plurality of cell state parameters.

Description

[Technical Field]

[0001] The present invention relates to a battery management device that differentially applies a balancing process to each of a plurality of battery cells depending on the electrical state of each of the plurality of battery cells.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0113716 filed on September 7, 2022, and Korean Patent Application No. 10-2023-0098407 filed on July 27, 2023, and the contents disclosed in the specifications and drawings of those applications are incorporated herein in their entirety. [Background technology]

[0003] As demand for portable electronic products that use electricity as a power source, such as laptops, video cameras, and mobile phones, has grown rapidly and mobile robots, electric bicycles, electric carts, and electric vehicles have become widely commercialized, active research is being conducted into high-performance secondary batteries that can be repeatedly charged and discharged.

[0004] Commercially available rechargeable secondary batteries (hereinafter referred to as "battery cells" or "cells") include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries have the advantages of being able to be freely charged and discharged because they have almost no memory effect compared to nickel-based secondary batteries, and have an extremely low self-discharge rate. In addition, they have the characteristics of high energy density and high operating voltage, so they have been researched intensively compared to other types of secondary batteries and are being used more widely in actual products.

[0005] BACKGROUND ART In recent years, battery cells have been widely used not only in small devices such as portable electronic devices but also in medium- to large-sized devices such as electric vehicles and energy storage systems (ESS).

[0006] In this case, a battery module in which a plurality of electrically connected battery cells are housed together inside a module case is mainly applied, and when high power or large capacity is required, a battery pack having a plurality of battery modules electrically connected in series and / or in parallel may also be applied.

[0007] Since such battery modules or battery packs (hereinafter collectively referred to as "batteries") are devices that provide power, energy efficiency is an important issue. Therefore, various efforts have been focused on increasing energy density, such as methods for implementing electrode assemblies as multiple unit laminates, methods for improving the physical properties of battery cells, and methods for increasing electrochemical efficiency.

[0008] From this perspective, in order to optimize battery performance, a balancing process is applied in which the electrical characteristics (voltage, SOC, etc.) of multiple battery cells contained in a battery are controlled uniformly (within an appropriate error range) by appropriately using a charging circuit or a discharging circuit, etc.

[0009] In multiple battery cells, the phenomenon of non-uniform electrical characteristics (e.g., voltage or SOC) occurs due to differences in individual dynamic states caused by material characteristics such as internal resistance, artificial deviations due to the usage environment, cooling efficiency, capacity, etc.

[0010] When variations in electrical characteristics occur, the actual available resources are not used in an optimized manner, resulting in a problem of the battery module's performance being lower than the actual available capacity or output.In addition, if at least one battery cell reaches its maximum electrical characteristics before the other battery cells, the charging process ends before the other battery cells with remaining internal capacity can be fully charged, which significantly limits the charge capacity of the entire battery module.

[0011] In an extreme example, if one battery cell has the lowest voltage (charging voltage) and another battery cell has the highest voltage, even if the remaining battery cells have the appropriate voltage, the battery may not be able to charge (storage energy) or discharge (supply power).

[0012] Furthermore, if the battery continues to be used without the voltage deviation being properly corrected, the voltage deviation will become even more severe, which will not only further deteriorate the battery's performance but may also cause safety issues such as fire due to overcharging.

[0013] The balancing process is a way to solve these problems by continuously controlling multiple battery cells to have a uniform electrical state, thereby providing effects such as maintaining stable battery performance, extending service life, and increasing output efficiency.

[0014] The balancing process involves charging battery cells with relatively low electrical characteristics through a separate power source, or transferring the energy of battery cells with relatively high electrical characteristics to battery cells with relatively low electrical characteristics. For ease of circuit configuration, stability, prevention of malfunctions, and clarity of operation, the method of discharging battery cells with relatively high electrical characteristics through a resistive circuit (load circuit) is mainly used.

[0015] However, such balancing is performed based only on formal values ​​that are externally measured or calculated, such as the voltage of the battery cell, without taking into consideration the actual characteristics of the battery cell.

[0016] For example, in the case of a battery cell that is highly deteriorated due to an increase in internal resistance, etc., its electrical characteristics become relatively lower than those of other battery cells during discharge. In this case, however, the conventional balancing process may discharge a healthy battery cell with high electrical characteristics, which can cause the problem of unnecessary consumption of available resources.

[0017] As described above, since balancing is performed continuously according to the current battery condition, such problems occur repeatedly as the battery is used, and since the deterioration rate has a tendency to accelerate over time, the balancing process cycle becomes shorter and shorter, which not only wastes energy and worsens driving performance, but also has a serious adverse effect on the battery life itself. Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention has been invented to solve the above problems, and aims to provide a battery management device and method that can optimize the driving performance of a battery module by selectively or differentially performing a balancing process on at least one battery cell among a plurality of battery cells, taking into consideration not only the electrical state of each of the plurality of battery cells included in a battery module but also the behavioral characteristics of each of the battery cells.

[0019] The technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems will be apparent to those skilled in the art from the following description of the invention. [Means for solving the problem]

[0020] According to one aspect of the present invention, a battery management device is provided for a battery module including a plurality of battery cells, the battery management device including: a state monitoring unit configured to acquire a plurality of cell state parameters indicating electrical states of the plurality of battery cells, a balancing processing unit configured to execute a balancing process that is a procedure for selectively discharging or charging each of the plurality of battery cells to suppress variations in the electrical states among the battery cells, and a control unit configured to control the balancing processing unit to execute the balancing process for at least one battery cell among the plurality of battery cells based on the plurality of cell state parameters.

[0021] The battery management device may further include a cell classifier configured to classify each of the battery cells as a degraded cell or a normal cell based on the cell state parameters, and the controller may control the balancing processor to perform the balancing process differentially based on the cell state parameters of the degraded cells and the normal cells.

[0022] The control unit may control the balancing unit to perform the balancing process on the degraded cell when a cell state parameter of the degraded cell is greater than a cell state parameter of the normal cell. The cell state parameter may indicate at least one of a voltage and a State of Charge (SOC).

[0023] The cell classification unit may include an input unit configured to acquire the plurality of cell state parameters from the state monitoring unit, a calculation processing unit configured to calculate a plurality of cell behavior parameters indicating behavior characteristics of the electrical states of the plurality of battery cells based on the plurality of cell state parameters, and a selection unit configured to classify each of the plurality of battery cells as the degraded cell or the normal cell based on the relative differences between the cell behavior parameters.

[0024] The cell behavior parameter may include a rate of change of the cell state parameter, and the cell classifier may be configured to classify each battery cell mapped to n (n is a natural number equal to or greater than 1) cell behavior parameters that are ranked highest in magnitude among the plurality of cell behavior parameters as the degraded cell.

[0025] The cell behavior parameter may include a rate of change of the cell state parameter. The cell classifier may be configured to select, as the degraded cell, each battery cell that satisfies both that the cell behavior parameter during a charging process of the battery module is equal to or greater than a first reference value and that the cell behavior parameter during a discharging process of the battery module is equal to or greater than a second reference value.

[0026] The state monitoring unit may be configured to obtain a SOC of the battery module as a module state parameter indicating an electrical state of the battery module.

[0027] The control unit may control the balancing processing unit to perform the balancing process on the degraded cells on condition that the module state parameter is equal to or higher than a reference SOC while the battery module is being charged.

[0028] The battery management device may further include an SOC information recording unit configured to record first SOC time series data and second SOC time series data, a statistical processing unit configured to calculate SOC statistics based on the first SOC time series data and second SOC time series data, and a reference setting unit configured to set the reference SOC similar to the SOC statistics.

[0029] The first SOC time series data may include first start SOC through (k-1)th start SOC indicating the SOC of the battery module at the start of each of the first through (k-1)th charging processes previously performed on the battery module. The second SOC time series data may include first end SOC through (k-1)th end SOC indicating the SOC of the battery module at the end of each of the first through (k-1)th charging processes, where k is a natural number greater than or equal to 2.

[0030] The statistical processing unit may be configured to calculate the SOC statistical value further based on a State of Health (SOH) of the battery module.

[0031] The statistical processing unit may be configured to determine a reference number based on the SOH of the battery module. The statistical processing unit may be configured to extract a (kj)th start SOC through a (k-1)th start SOC from the first SOC time series data. The statistical processing unit may be configured to extract a (kj)th end SOC through a (k-1)th end SOC from the second SOC time series data. The statistical processing unit may be configured to calculate the SOC statistical value equal to the average value of the (kj)th start SOC through the (k-1)th start SOC and the (kj)th end SOC through the (k-1)th end SOC, where j is the reference number.

[0032] A battery pack according to another aspect of the present invention includes the battery management device.

[0033] An electric vehicle according to yet another aspect of the present invention includes the battery pack.

[0034] According to yet another aspect of the present invention, a battery management method can be performed by the battery management device, the battery management method including: a state monitoring unit acquiring a plurality of cell state parameters indicating electrical states of the plurality of battery cells; and a control unit controlling the balancing processing unit to perform the balancing process on at least one battery cell among the plurality of battery cells based on the plurality of cell state parameters in order to suppress variations in the electrical states among the battery cells.

[0035] The step of controlling the balancing processing unit may include the steps of classifying each of the plurality of battery cells as a degraded cell or a normal cell based on the plurality of cell state parameters, and controlling the balancing processing unit so that the balancing process is performed differentially based on the cell state parameters of the degraded cells and the cell state parameters of the normal cells.

[0036] The step of controlling the balancing processing unit may include a step of acquiring an SOC of the battery module as a module state parameter indicating an electrical state of the battery module, and a step of controlling the balancing processing unit so that the balancing process for the degraded cells is performed on the condition that the module state parameter is equal to or greater than a reference SOC while the battery module is being charged. [Effects of the Invention]

[0037] According to one aspect of the present invention, time-series changes in the electrical state and / or behavior characteristics of each of a plurality of battery cells can be used to identify operating conditions that do not induce a weakening of the driving performance of the battery module, and a balancing process can be selectively performed on at least one of the plurality of battery cells while the identified operating conditions are met.

[0038] In addition, according to one aspect of the present invention, it is possible to precisely classify each of the multiple battery cells of a battery module into normal cells or degraded cells, and the classification results can be organically combined with control operations for the balancing process to improve the performance of the battery module.

[0039] In addition, according to one aspect of the present invention, by selectively allowing the execution of a balancing process for at least one battery cell in consideration of the difference between the behavioral characteristics of a normal cell and that of a degraded cell, it is possible to effectively solve problems such as unnecessary limitations on the available capacity and output of normal cells, as well as problems such as the fixed deterioration of performance or shortened lifespan.

[0040] Furthermore, according to one aspect of the present invention, a statistical value for the SOC swing range, which is the main usage range of the battery module, is calculated based on the charge history and / or discharge history of the battery module, and the statistical value is used as a kind of criterion for differential execution of the balancing process, thereby improving the efficiency of the balancing process.

[0041] According to one aspect of the present invention, a balancing process may be performed only on battery cells classified into either a degraded cell or a normal cell. When the balancing process is performed only on the degraded cells instead of the normal cells, it is advantageous in that the state deviation between the normal cells and the degraded cells is quickly eliminated. When the balancing process is performed only on the normal cells instead of the degraded cells, the charging and discharging of the degraded cells due to the balancing process is reduced accordingly, which helps to equalize the life deviation between the normal cells and the degraded cells.

[0042] The present invention can also provide various other effects, which will be described in the respective embodiments, but the description of effects that can be easily inferred by those skilled in the art will be omitted.

[0043] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0044] [Figure 1] 1 is a block diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention; [Figure 2] 2 is a diagram illustrating a schematic configuration of a cell classification unit illustrated in FIG. 1. FIG. [Figure 3] FIG. 10 is a block diagram illustrating a schematic configuration of a battery pack according to another embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram schematically illustrating the configuration of a reference processing unit illustrated in FIG. 3. [Figure 5] 2 is a flow chart illustrating an example of a battery management method that can be performed by the battery management device shown in FIG. 1. [Figure 6] 1. FIG. 4 is a flow chart illustrating another example of a battery management method that can be performed by the battery management device shown in FIG. [Figure 7] 1. FIG. 4 is a flow chart illustrating yet another example of a battery management method that can be performed by the battery management device shown in FIG. [Figure 8] FIG. 10 is a flow diagram illustrating a process for classifying each of a plurality of battery cells as a normal cell or a degraded cell. [Figure 9] 4 is a flow diagram illustrating a process that can be performed by the battery management unit shown in FIG. 3. [Figure 10] FIG. 1 is a flow chart referred to for explaining the process of determining a reference SOC. [Figure 11] 1 is a diagram referred to for illustratively explaining the change in the SOC of a battery cell over time. [Figure 12] 1A and 1B are diagrams referred to for explaining the behavior characteristics of normal cells and the behavior characteristics of degraded cells. [Figure 13] FIG. 13 is an enlarged view of the dotted area shown in FIG. 12. [Figure 14] FIG. 10 is a diagram referred to for explaining a process of differentially performing a balancing process on a degraded cell and a normal cell depending on a reference SOC. [Figure 15] FIG. 10 is a diagram referenced to explain the differential balancing process performed when the reference SOC is 80%. [Figure 16] FIG. 4 is a diagram referred to for schematically explaining an example of the balancing processing unit shown in FIGS. 1 and 3. [Figure 17] 4 is a diagram referred to for roughly explaining another example of the balancing processing unit shown in FIGS. 1 and 3. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0045] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0046] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0047] Terms including ordinal numbers such as "first," "second," etc. are used to distinguish one of various components from other components, and do not limit the components.

[0048] Throughout the specification, when a part "includes" a certain element, this does not exclude other elements and means that it may further include other elements unless otherwise specified. Furthermore, terms such as "controller" in the specification refer to a unit that processes at least one function or operation, and may be embodied in hardware, software, or a combination of hardware and software.

[0049] Furthermore, throughout this specification, when a part is referred to as being "connected" to another part, this includes not only a "direct connection" but also an "indirect connection" via other elements.

[0050] FIG. 1 is a block diagram illustrating a schematic configuration of a battery pack according to an embodiment of the present invention, and FIG. 5 is a flow chart illustrating an example of a battery management method that can be performed by the battery management device illustrated in FIG. 1.

[0051] As shown in FIG. 1, the battery pack 10 includes a battery module 50 and a battery management device 100.

[0052] The battery module 50 includes a plurality of battery cells (#1 to #N), where N is a natural number equal to or greater than 1 and may indicate the total number of battery cells included in the battery module 50. The plurality of battery cells (#1 to #N) may be electrically connected in series with one another. When describing content common to the plurality of battery cells (#1 to #N), the battery cell is denoted by reference numeral 51. Although FIG. 1 illustrates the battery cell 51 as a single unit, this is merely an example, and according to an embodiment, the battery cell 51 may be a cell assembly formed by grouping a plurality of cell units connected in parallel with one another.

[0053] The battery management device 100 can monitor the electrical state of each of the plurality of battery cells (#1 to #N) and the electrical state of the battery module 50.

[0054] As will be described later, the battery management unit 100 executes and controls a balancing process of a plurality of battery cells (#1 to #N).

[0055] It is preferable that the battery cells (#1 to #N) are configured to have the same level of performance and specifications so that the electrical characteristics as well as the charge / discharge efficiency can be stably maintained and managed.

[0056] The battery management device 100 may include a measurement unit 110, a state monitoring unit 120, a balancing processing unit 130, a control unit 140, a cell classification unit 150, and an interface unit 160.

[0057] The battery management system 100 may be realized by applying various combinations of electronic elements and components such as a storage means, a processing means, an input / output means, etc. The components of the battery management system 100 shown in FIG. 1 may be physically separated, or alternatively, may be functionally or logically separated.

[0058] In other words, since each component corresponds to a logical component for realizing the technical idea of ​​the present invention, even if each component is configured as an integrated or separated component, it is considered to fall within the scope of the present invention as long as it can perform the function of the logical component of the present invention, and components performing the same or similar functions are considered to fall within the scope of the present invention regardless of the consistency of their names or the division or integration of their components. The same applies to the configurations of the present invention shown in Figures 2 to 4.

[0059] The state monitoring unit 120 calculates a plurality of cell state parameters indicating the electrical state of each of the plurality of battery cells (#1 to #N) and / or a module state parameter indicating the electrical state of the battery module 50 (S520, see FIG. 5). The module state parameter is an electrical characteristic based on the entire battery module 50 and may depend on the plurality of cell state parameters. The module state parameter may be a value representative of the plurality of cell state parameters. As an example, the SOC of the battery module 50 as a module state parameter may be determined as an average SOC of the plurality of battery cells (#1 to #N) according to the plurality of cell state parameters.

[0060] In an embodiment, the status monitoring unit 120 may be linked to the measurement unit 110, which may be implemented using various voltage sensors, current sensors, temperature sensors, measuring devices, etc., known at the time of filing. When the measurement unit 110 measures the electrical characteristics (voltage, current, and / or temperature) of the plurality of battery cells (#1 to #N) or the battery module 50 (S510), the status monitoring unit 120 may collect (acquire) the electrical characteristics of the battery cells 51 at a fixed sampling rate or a variable sampling rate, which indicate the measured values ​​of the electrical characteristics. In this case, the measured values ​​of the electrical characteristics of the battery cells 51 may themselves be cell status parameters. Alternatively, the status monitoring unit 120 may be configured to determine cell status parameters of the battery cells 51 and module status parameters (e.g., SOC, SOH, etc.) of the battery module 50 by applying a functional calculation process to the measured values ​​of the electrical characteristics of the battery cells 51.

[0061] The cell state parameters indicate the electrical state of the battery cell 51 and may include at least one of voltage, current, temperature, SOC, and SOH. The cell state parameters may be generated periodically at unit time intervals that can be variably set by design of hardware or software.

[0062] In an embodiment, the cell state parameter acquisition period may be set shorter as the discharge or charge rate increases, and longer as the discharge or charge rate decreases. The correspondence between the discharge or charge rate and the cell state parameter acquisition period may be pre-recorded in a look-up table.

[0063] According to such an embodiment, the more rapidly power is used, the more precise information can be interfaced to the user, etc., and in sections where the need for precise information provision is relatively low, the calculation processing speed, amount of calculation, etc. can be reduced, thereby improving the efficiency of data processing.

[0064] It is preferable that the cell state parameters and / or module state parameters are configured to be generated during each of the charging process in which power is supplied (stored) in the battery module 50 from an external power supply device, as well as the discharging process in which power is supplied to a load such as an electric motor, so that the electrical state or behavior characteristics of the battery cell 51 can be more precisely understood.

[0065] The balancing processor 130 is configured to perform a balancing process on a plurality of battery cells (#1 to #N) constituting the battery module 50, and may include well-known hardware components such as a relay (switch), a load resistor, a timer, etc. The balancing processor 130 is electrically connected to the battery cells 51, and may be configured to perform functions such as discharging and / or charging the corresponding battery cells 51 according to control signals, etc. The hardware implementation of the balancing processor 130 will be described later with reference to FIGS. 16 and 17.

[0066] When the module status parameter of the battery module 50 is generated, the control unit 140 executes a procedure (S530) of determining whether the module status parameter satisfies a predetermined specific condition for starting a balancing process. As an example, the specific condition may be a combination of (i) the module status parameter being equal to or greater than a reference SOC and (ii) the voltage of a degraded cell being higher than the voltage of a normal cell. As another example, the specific condition may be a combination of (i) the module status parameter being equal to or less than a reference SOC and (ii) the voltage of a normal cell being higher than the voltage of a degraded cell. If the value of step S530 is "yes," the control unit 140 controls the balancing processing unit 130 to perform a balancing process on at least one battery cell among the plurality of battery cells (#1 to #N) (S540).

[0067] The above-described process of the present invention may be designed to be applied cyclically so that continuous battery management is maintained unless an event such as power off, firmware replacement, or satisfaction of a preset termination condition occurs. Depending on the embodiment, the step of checking whether a termination condition is satisfied (S550) may be omitted from the method of Fig. 5. The termination condition may be, for example, that the voltage deviation (e.g., the difference between the maximum voltage and the minimum voltage) of the plurality of battery cells (#1 to #N) falls within a predetermined tolerance range.

[0068] When an event requiring balancing occurs in which the voltage deviation of any battery cell (e.g., #1) among the plurality of battery cells (#1 to #N) becomes equal to or greater than a reference deviation, the battery management device 100 may proactively determine a negative situation in which the balancing process may actually result in a decrease in performance of the battery module 50 or deterioration of the battery cell (e.g., #1), instead of immediately performing a balancing process on the battery cell (e.g., #1).

[0069] The battery management unit 100 is configured to execute the balancing process for the battery cell (e.g., #1) only when it is determined that executing the balancing process for the battery cell (e.g., #1) will not result in any negative consequences. Here, the voltage deviation of a battery cell (e.g., #1) may refer to the difference between the average voltage value of the plurality of battery cells (#1 to #N) and the voltage value of the battery cell (e.g., #1).

[0070] FIG. 6 is a flow chart illustrating another example of a battery management method that can be performed by the battery management device shown in FIG.

[0071] 6, the state monitoring unit 120 acquires a plurality of cell state parameters indicating the electrical states of the plurality of battery cells (#1 to #N) (S610). The state monitoring unit 120 may generate and store the cell state parameters of the plurality of battery cells (#1 to #N) in cooperation with the measurement unit 110.

[0072] In an embodiment, the status monitoring unit 120 may directly utilize the cell status parameters measured by the measurement unit 110, but if the signal output from the measurement unit 110 contains noise components such as impulses or fluctuation waves due to signal interference, distortion, disturbance, etc., the status monitoring unit 120 may include a hardware configuration that appropriately adjusts or filters these components, or the status monitoring unit 120 may be equipped with an algorithm for processing them in a software manner.

[0073] The battery management device 100 corresponds to an embodiment in which, through a comparison of the electrical states and / or behavioral characteristics of a plurality of battery cells (#1 to #N), the battery cells falling within the normal range (hereinafter referred to as "normal cells") and the battery cells having relatively deteriorated behavioral characteristics (hereinafter referred to as "deteriorated cells") are chronologically distinguished over time, and a balancing process is differentially applied to the plurality of battery cells (#1 to #N) using the results.

[0074] The voltage value not only has the advantage of being able to be measured or generated with a relatively simple circuit configuration (such as a configuration for measuring the voltage difference between both ends of the battery cell 51), but also has the characteristic of clearly representing the intrinsic characteristics of the battery cell 51 externally, so when used as raw data, it is possible to clearly estimate and determine whether the cell is degraded or not.

[0075] In this respect, the cell state parameter is not particularly limited as long as it can indicate the electrical state of the battery cell 51 as described above, and typically includes the voltage value of the battery cell 51.

[0076] When the cell state parameters (e.g., voltage values) of each of the plurality of battery cells (#1 to #N) are acquired by the state monitoring unit 120 (S610), the cell classifying unit 150 may classify each of the plurality of battery cells (#1 to #N) of the battery module 50 into a degraded cell or a normal cell using the individual voltage values ​​of the plurality of battery cells (#1 to #N) (S620). An embodiment of the present invention for classifying normal cells and degraded cells will be described in detail later.

[0077] In this case, the control unit 140 controls the balancing processing unit 130 so that the balancing process is performed differently depending on the cell state parameters of the degraded cells and the normal cells (S640).

[0078] Specifically, in step S630, the control unit 140 may determine whether the module status parameter satisfies a predetermined specific condition for starting the execution of the balancing process. Step S630 may be executed on the condition that the module status parameter is equal to or greater than the reference SOC or the module status parameter is equal to or less than the reference SOC.

[0079] FIG. 14 is a diagram referred to for explaining the process of differentially performing the balancing process on degraded cells and normal cells according to the reference SOC.

[0080] The control unit 140 may control the balancing process to be performed on the degraded cells (S640). As an example, if the module state parameter is equal to or greater than the reference SOC, the control unit 140 may control the balancing processing unit 130 (see FIG. 16) to perform the balancing process on the degraded cells in a time period when the voltage of the degraded cells is higher than the voltage of the normal cells (the "DA" period in FIG. 14). As another example, if the module state parameter is equal to or less than the reference SOC, the control unit 140 may control the balancing processing unit 130 (see FIG. 17) to perform the balancing process on the degraded cells in a time period when the voltage of the normal cells is higher than the voltage of the degraded cells (the "DI" period in FIG. 14).

[0081] Here, the balancing process for the degraded cells may refer to a balancing process for each battery cell classified as a degraded cell among the plurality of battery cells (#1 to #N).

[0082] On the other hand, if the result of step S630 is "No," the balancing processor 130 may be controlled to deactivate all balancing processes for the degraded cells and the normal cells. This process may also be configured to be applied recursively depending on whether the termination condition is satisfied, as described above. Depending on the embodiment, the step of checking whether the termination condition is satisfied (S650) may be omitted.

[0083] Hereinafter, a specific embodiment of the present invention in which each of a plurality of battery cells (#1 to #N) is classified into a deteriorated cell or a normal cell will be described in detail with reference to FIGS. 2, 7, and 8. FIG.

[0084] As shown in FIG. 2, the cell classifier 150 may include an input unit 151, a calculation processing unit 153, and a selection unit 155.

[0085] The behavioral characteristics of the battery cells 51 will be described with reference to Figures 11 and 12, and then the specific functions of the selection unit 155 that organically reflects the behavioral characteristics to select deteriorated cells and normal cells will be described in detail below.

[0086] 11 is a diagram referred to for exemplarily explaining the change over time in the SOC of the battery cell 51. The SOC of the battery cell 51 may be included as a cell state parameter of the battery cell 51.

[0087] 11, the battery cell 51 has a behavior characteristic in which the voltage value rises (increases) during the charging period (t0 to t1). Therefore, the SOC of the battery cell 51, which is estimated by applying a functional operation to the voltage value, also has a behavior characteristic in which the SOC rises (increases).

[0088] After charging is completed (e.g., a fully charged state where the SOC reaches 100%), the SOC of the battery cell 51 is maintained constant during a rest period (t1 to t2) in which both charging and discharging are stopped, ignoring other external factors such as standby current consumption. Thereafter, during a discharge period (t2 to t3) for driving a load means (such as an electric motor), the voltage value and SOC of the battery cell 51 exhibit a downward (decreasing) behavior characteristic.

[0089] After the rest period (t3 to t4) following the discharge period (t2 to t3) ends, a charging period (t4 to t5) begins again via an external power supply, etc., and the voltage value and SOC of the battery cell 51 increase again during the charging period (t4 to t5). Such behavioral characteristics of the battery cell 51 are repeated chronologically during the progress of charging, resting, and / or discharging.

[0090] 11 is a graph illustrating an embodiment in which a full charge (SOC 100%) and a full discharge (SOC 0%) are performed. The behavioral characteristics of the battery cell 51, in which the SOC of the battery cell 51 increases (slope S1) during charging and decreases (slope S2) during discharging, correspond to the essential characteristics of the battery cell 51.

[0091] For reference, in Fig. 11 and the like, for convenience of explanation, the behavior characteristics of the battery cell 51 are shown to change linearly with time, but it goes without saying that linearity and nonlinearity are mixed in the behavior characteristics of the actual battery cell 51. When the measurement and generation of electrical characteristics are performed intermittently at specific cycles, the characteristics may become discontinuous, unlike the drawings, unless post-processing such as interpolation is taken into consideration.

[0092] FIG. 12 is a diagram referred to for explaining the behavior characteristics of the normal cell N-Cell and the degraded cell D-Cell, and FIG. 13 is an enlarged view of the dotted line area B shown in FIG.

[0093] As described above with reference to FIG. 11, the voltage values ​​of both the normal cell N-Cell and the degraded cell D-Cell rise during charging and fall during discharging.

[0094] If performance degradation occurs in the battery cell 51 due to aging over time, material characteristics, artificial usage environment, etc., most of the factors and factors that cause performance degradation are expressed as inherent resistance components, and therefore the internal resistance and related resistance components (collectively referred to as "internal resistance") of the cell in which performance degradation or deterioration has occurred will increase.

[0095] According to the general law (Ohm's law) regarding the correlation between voltage and current, the battery cell 51 with a relatively increased internal resistance will have a relatively higher voltage rise than the other battery cells 51 even when the same amount of current flows. In other words, even when a relatively small current flows, the voltage rises to the same level as the other battery cells 51.

[0096] As described above, since the SOC is calculated functionally from the voltage of the battery cell 51, the SOC also has a characteristic change corresponding to the change in voltage.

[0097] From the viewpoint of discharging, discharging is the release of the charge (charge, current component) stored in the battery cell 51 to the outside. Therefore, when the same amount of current is released to the outside, the voltage drop will be relatively larger than that of other battery cells 51 due to the difference in internal resistance.

[0098] 12, during the same charging period (t0 to t1), the voltage of the degraded cell D-Cell rises significantly from Va2 to Va1, while the voltage of the normal cell N-Cell rises only slightly from Vb2 to Vb1. In other words, the amount of voltage change during the same charging period for the degraded cell D-Cell is relatively larger than that for the normal cell N-Cell.

[0099] During the same discharge period (t2 to t3), the voltage of the degraded cell D-Cell drops from Va1 to Va2, while the voltage of the normal cell N-Cell drops from Vb1 to Vb2, so the voltage change rate of the degraded cell D-Cell is greater than that of the normal cell N-Cell during the discharge period (t2 to t3). In other words, during both the charge and discharge processes, the degraded cell D-Cell has a relatively larger rate of change in its electrical characteristics (such as voltage) than the normal cell N-Cell.

[0100] Although the figures show the behavior characteristics of the charging and discharging processes as corresponding (symmetrical) to each other, the behavior characteristics of the charging and discharging processes may not correspond (symmetrical) due to the influence of external factors such as the power characteristics and specifications of the external power supply means and the load means (such as an electric motor), as well as the inherent electrochemical characteristics of charging and discharging.

[0101] Based on these behavioral characteristics, the cell behavior parameters of the normal cell N-Cell and the degraded cell D-Cell as shown in FIG. 13 can be expressed by the following equations.

number

[0102] In the formula, Δt is a predetermined small time, SD is the rate of change of the voltage value as a cell characteristic parameter of the degraded cell D-Cell, and SN is the rate of change of the voltage value as a cell characteristic parameter of the normal cell N-Cell. Therefore, SD has a larger value than SN during the charging process, and SD also has a larger value (absolute value basis) than SN during the discharging process.

[0103] In this way, the performance degradation level of the battery cell 51 can be effectively identified based on the voltage value of the battery cell 51 at a specific point in time and / or the transition of the voltage value over time (cell behavior parameter).

[0104] Furthermore, the degree or magnitude of deterioration of each of the plurality of battery cells (#1 to #N) may be mathematically quantified through a relative comparison of the magnitude (absolute value magnitude) of the rate of change per time of the cell status parameters of each of the plurality of battery cells (#1 to #N). That is, the plurality of battery cells (#1 to #N) may be ranked in ascending or descending order based on their respective cell behavior parameters (corresponding to the degree of deterioration).

[0105] The cell classification unit 150 is configured to classify each of the plurality of battery cells (#1 to #N) into a degraded cell D-Cell or a normal cell N-Cell based on a plurality of cell behavior parameters that indicate the behavior characteristics of the electrical state of each of the plurality of battery cells (#1 to #N).

[0106] FIG. 7 is a flow chart illustrating yet another example of a battery management method that can be performed by the battery management device shown in FIG.

[0107] Referring to FIG. 7, when the cell state parameters (e.g., voltage, SOC, etc.) of the battery cell 51 are inputted in time series from the state monitoring unit 120 to the input unit 151 (S710), the calculation processing unit 153 calculates cell behavior parameters indicating the behavior characteristics of the cell state parameters of the battery cell 51 (S720).

[0108] As described above, the cell behavior parameter of any battery cell 51 may include the rate of change per time of the cell state parameter of the battery cell 51. In an embodiment, the behavior characteristic may be the rate of change per time of the SOC or the magnitude difference value of the SOC generated through functional processing of the difference values, voltage values, etc. of the electrical characteristics at multiple points in time or multiple time intervals.

[0109] Once the cell behavior parameters of the battery cell 51 are calculated, the selection unit 155 classifies each of the multiple battery cells (#1 to #N) into a degraded cell D-Cell or a normal cell N-Cell based on the relative differences between the multiple cell behavior parameters that correspond one-to-one to the multiple battery cells (#1 to #N).

[0110] If the number of target cells identified in step S730 is equal to or less than a predetermined number (n, a natural number greater than or equal to 1 and less than N), all of the identified target cells may be classified as degraded cells. If the number of target cells identified in step S730 exceeds the predetermined number (n), step S740 may be performed.

[0111] In operation S740, the selection unit 155 may sort the plurality of cell behavior parameters that are one-to-one mapped to the plurality of target cells identified in operation S730 in order of magnitude, and select each battery cell that is mapped to the predetermined number (n) of cell behavior parameters that correspond to the highest ranking as a degraded cell (D-cell) (S740). The remaining battery cells that are not selected as degraded cells (D-cell) in operation S740 are classified as normal cells.

[0112] The set number (n) may be a predetermined constant. Alternatively, the selection unit 155 may determine the set number (n) based on environmental information such as battery efficiency, current output characteristics, specifications of the load means (e.g., electric motor), durability of the battery cells, service life of the battery cells, charge / discharge cycle, and SOH. The above-described process may also be configured to be recursively applied depending on whether the termination condition is satisfied, as described above. Depending on the embodiment, the step of checking whether the termination condition is satisfied (S750) may be omitted.

[0113] In addition, the selection unit 155 may be configured to determine (S730) whether there is a battery cell (hereinafter also referred to as a "target cell") whose cell behavior parameter (such as the rate of change per hour of a cell state parameter or its absolute value) of the battery cell 51 is greater than or equal to a reference value, and then select at least one of the target cells as a degraded cell D-Cell (S740).

[0114] According to this embodiment, in which the target cell is first determined before selecting the degraded cell D-Cell, errors due to noise signals, the temporary nature of deviations, voltage deviations that do not adversely affect the normal operation of the battery, etc. can be filtered more precisely, thereby further optimizing the efficiency of differential application of the balancing process.

[0115] The reference value (also referred to as a "reference change rate") may be set to a calculated average value, a weighted average value, a change rate having a standard deviation range, an average value excluding maximum and minimum values, etc. of the cell behavior parameters of all battery cells (#1 to #N) constituting the battery module 50. The reference value may be determined in advance separately for charging and discharging.

[0116] Also, a value that makes the number of normal cells N-Cells greater than the number of degraded cells D-Cells based on the number of selected cells may be set as the reference value. For example, if the total number N of battery cells (#1 to #N) included in the battery module 50 is 30, a value that makes the number of battery cells 51 classified as normal cells N-Cells at least 16 may be set as the reference rate of change.

[0117] According to such an embodiment, not only can the time period during which the balancing process is inactivated be optimized, but also the energy consumption of the degraded cell D-Cell due to the balancing process can be appropriately limited, thereby maintaining the output performance of the entire battery module 50 so that it does not deviate significantly from the normal range.

[0118] If each of the plurality of battery cells (#1 to #N) is classified as a normal cell N-Cell or a degraded cell D-Cell, the control unit 140 may control the balancing process to be performed on the degraded cell D-Cell at least during the time period DA, as shown in Figure 12. The time period DA belongs to the charging period of the battery module 50, and during the time period DA, the voltage value of the degraded cell D-Cell is equal to or greater than the voltage value of the normal cell N-Cell.

[0119] The control unit 140 controls the balancing process not to be performed even if a voltage deviation occurs during a period (DI) in which the voltage value of the degraded cell D-Cell is lower than the voltage value of the normal cell N-Cell, i.e., when the voltage value of the normal cell N-Cell is higher than the voltage value of the degraded cell D-Cell. The time period DI belongs to the discharge period of the battery module 50.

[0120] On the other hand, if the voltage deviations of all the battery cells (#1 to #N) are less than the reference deviation, the balancing process is not performed on any of the battery cells (#1 to #N).

[0121] The battery management unit 100 can perform the balancing process differentially by selecting the normal cell N-Cell and the degraded cell D-Cell and using the behavior characteristics of their electrical characteristics (such as voltage values). Table 1 below is an example of operating conditions referenced for performing the balancing process. [Table 1]

[0122] FIG. 8 is a flow diagram showing a process for classifying each of a plurality of battery cells (#1 to #N) into a normal cell N-Cell or a deteriorated cell D-Cell.

[0123] 8, when the cell state parameters (e.g., voltage, etc.) of the battery cell 51 are input from the state monitoring unit 120 to the input unit 151 (S810), the calculation processing unit 153 calculates the cell behavior parameters from the cell state parameters of the battery cell 51 (S820). The calculation of the cell behavior parameters has been described above with reference to FIG. 7, and therefore a detailed description thereof will be omitted.

[0124] Then, the selection unit 155 may be configured to select a degraded cell, such as D-Cell, based on each of the charging procedure and the discharging procedure.

[0125] Specifically, the selection unit 155 may rank the battery cells (#1 to #N) by sorting the cell behavior parameters, which are mapped one-to-one to the battery cells (#1 to #N), in order of magnitude during at least one of a discharging process and a charging process.

[0126] The selection unit 155 may be configured to execute a step (S830) of confirming the presence of a first target cell, which is a battery cell whose cell behavior parameter acquired during charging is equal to or greater than a first reference value, and a step (S840) of confirming the presence of a second target cell, which is a battery cell whose cell behavior parameter (absolute value) acquired during discharging is equal to or greater than a second reference value, based on a plurality of cell behavior parameters indicating individual behavior characteristics of the plurality of battery cells (#1 to #N) input in time series from the calculation processing unit 153. The cell behavior parameter acquired during charging is referred to as the first cell behavior parameter, and the cell behavior parameter acquired during discharging is referred to as the second cell behavior parameter. The first reference value may be an average value of the first cell behavior parameters of the plurality of battery cells (#1 to #N). The second reference value may be an average value of the second cell behavior parameters of the plurality of battery cells (#1 to #N).

[0127] In order to optimize each reference value, the length of time of the charging process for determining the first cell behavior parameter and the length of time of the discharging process for determining the second cell behavior parameter may each be set to be equal to or greater than a predetermined reference time.

[0128] In this way, a process of checking whether the cell behavior parameter of each of the plurality of battery cells (#1 to #N) is equal to or greater than a first reference value when charging, and a process of checking whether the cell behavior parameter of each of the plurality of battery cells (#1 to #N) is equal to or greater than a second reference value when discharging, can be performed in advance.

[0129] The selection unit 155 may be configured to select a battery cell 51, among the plurality of battery cells (#1 to #N), whose cell behavior parameters are identified as being equal to or greater than a reference value in both the charging process and the discharging process, as a deteriorated cell D-Cell (S850).

[0130] In step S850, if the number of battery cells among the plurality of battery cells (#1 to #N) that correspond to both the first target cell and the second target cell is less than or equal to a critical number (m, where m is a natural number greater than or equal to 1 and less than N), the selection unit 155 may select each of the battery cells that correspond to both the first target cell and the second target cell as a degraded cell D-Cell.

[0131] Meanwhile, if the number of battery cells corresponding to both the first target cell and the second target cell among the plurality of battery cells (#1 to #N) exceeds a critical number (m), the selection unit 155 may select only the critical number (m) of battery cells among the battery cells corresponding to both the first target cell and the second target cell as degraded cells D-Cell (S850). In this case, the critical number (m) of battery cells may be selected as degraded cells D-Cell in descending order of the average values ​​of the cell behavior parameters related to the charging process and the cell behavior parameters related to the discharging process.

[0132] According to this embodiment, as described above, errors due to noise signals, the transience of deviations, etc. can be eliminated in advance, thereby improving the overall efficiency and accuracy of the balancing process.

[0133] The critical number (m) may be a predetermined constant, or alternatively, it is preferable that the critical number (m) is variably set based on the efficiency of the battery, the current output characteristics, the specifications of the load means (such as an electric motor), the durability of the battery cells, the period of use of the battery cells, the charge / discharge cycle, environmental information such as SOH, etc.

[0134] Although not separately illustrated, input / output or measured data or information, calculated data or information, etc. may be recorded, updated, or read and utilized in hardware means in which the corresponding functions are implemented. The process shown in Figure 8 may also be designed to be applied cyclically. Depending on the embodiment, the step of checking whether the termination condition is satisfied (S860) may be omitted.

[0135] The control unit 140 may intentionally not perform the balancing process for the normal cell N-Cell during the time period in which the voltage of the normal cell N-Cell is maintained higher than the voltage of the degraded cell D-Cell, but may control the balancing process for the degraded cell D-Cell to be performed only during the time period in which the voltage of the degraded cell D-Cell is maintained higher than the voltage of the normal cell N-Cell.

[0136] This prevents the energy charged to the normal cell N-Cell, which has sufficient available capacity and excellent behavior characteristics, from being unnecessarily consumed by the balancing process, and effectively solves the problem of the available capacity of the battery module 50 not being fully utilized due to the SOC of the battery module 50 being limited early due to the behavior characteristics of the degraded cell D-Cell.

[0137] The control unit 140 may be configured to transmit various information and data generated by the above-described processes to an external control device 200 provided in an electric vehicle or the like through the interface unit 160. The control unit 140 may be configured to execute various processes according to the present invention based on control signals or set values ​​received from the external control device 200 through the interface unit 160.

[0138] In addition, the cell classification unit 150 or the control unit 140 may be configured to transmit alarm information regarding the need to replace the battery cell (e.g., #1) to the external control device 200 via the interface unit 160 when a battery cell (e.g., #1) selected as a degraded cell D-Cell is identified continuously for a specific period of time or repeatedly for a specific number of times.

[0139] From this perspective, if the identification information of the battery cells 51 that constitute the battery module 50 is stored in a database in advance, information that physically identifies the battery cells 51 classified as degraded cells D-Cell can also be transmitted to the external control device 200 together with the alarm information.

[0140] FIG. 3 is a block diagram illustrating a schematic configuration of a battery pack according to another embodiment of the present invention, and FIG. 9 is a flow chart illustrating a process that can be performed by the battery management device shown in FIG.

[0141] The battery pack 10 shown in FIG. 3 includes a battery module 50 and a battery management device 100.

[0142] The battery management device 100 is provided to control the balancing process of each of a plurality of battery cells (#1 to #N) to be performed differentially, reflecting a reference SOC or a statistical value calculated based on a user's charging / discharging pattern.

[0143] 3, the reference processing unit 170 is replaced with the cell classification unit 150. However, this is only one embodiment, and the battery management device 100 may be embodied in a form including both the reference processing unit 170 and the cell classification unit 150.

[0144] The reference processing unit 170 stores a reference SOC that is used for differential control of the balancing process performed by the balancing processing unit 130 .

[0145] In step S910, the state monitoring unit 120 acquires from the measurement unit 110 a plurality of cell state parameters (for example, voltage values, etc.) that are mapped one-to-one to a plurality of battery cells (#1 to #N).

[0146] In step S920, the status monitoring unit 120 calculates module status parameters indicating the electrical status of the battery module 50 based on the plurality of cell status parameters. The module status parameters include the SOC of the battery module 50. The SOC of the battery module 50 may be an average value, a minimum value, or a maximum value of the SOC of the plurality of battery cells (#1 to #N) based on the plurality of cell status parameters.

[0147] In step S930, the control unit 140 may determine whether the current module status parameter (e.g., SOC) is equal to or greater than the reference SOC stored in the reference processing unit 170. If the value of step S930 is "Yes," the process proceeds to step S932. If the value of step S930 is "No," the process proceeds to step S934.

[0148] In step S932, the control unit 140 may determine whether the voltage of the degraded cell is higher than the voltage of the normal cell. If the value of step S932 is "YES", the control unit 140 proceeds to step S940.

[0149] In step S934, the control unit 140 may determine whether the voltage of the normal cell is higher than the voltage of the degraded cell. If the value of step S934 is "YES", the control unit 140 proceeds to step S940.

[0150] In operation S940, the control unit 140 may control the balancing processing unit 130 to perform a balancing process on at least one battery cell classified as a degraded cell D-Cell among the plurality of battery cells (#1 to #N).

[0151] When proceeding from step S932 to step S940, the control unit 140 may control the balancing processing unit 130 shown in Fig. 16 to perform a balancing process for the degraded cell D-Cell. On the other hand, when proceeding from step S934 to step S940, the control unit 140 may control the balancing processing unit 130 shown in Fig. 17 to perform a balancing process for the degraded cell D-Cell.

[0152] The above process may also be configured to be applied recursively depending on whether the termination condition is satisfied, etc. Depending on the embodiment, the step of checking whether the termination condition is satisfied (S950) may be omitted.

[0153] In this regard, in order to classify each of the plurality of battery cells (#1 to #N) into a degraded cell D-cell or a normal cell N-cell, at least one of a charging process and a discharging process must be performed prior to the cell classification procedure. Therefore, the charging process and the discharging process performed prior to the cell classification procedure may be referred to as a pre-charging process and a pre-discharging process, respectively.

[0154] As an example, step S510 of FIG. 5, step S610 of FIG. 6, step S710 of FIG. 7, step S810 of FIG. 8, and step S910 of FIG. 9 may each be performed during at least one of the pre-charging process and the pre-discharging process.

[0155] Also, step S540 of FIG. 5, step S640 of FIG. 6, and step S940 of FIG. 9 may be performed in the charging process and / or discharging process subsequent to the pre-charging process and / or pre-discharging process, respectively.

[0156] As described above with reference to Figure 11, the cell behavior parameters of the degraded cell D-Cell may be relatively larger than the cell behavior parameters of the normal cell N-Cell. In other words, under conditions where the same current flows, the degraded cell D-Cell has behavior characteristics in which its charge rate and discharge rate are higher than the charge rate and discharge rate of the normal cell N-Cell.

[0157] The SOC of the battery module 50 may be determined depending on the battery cell 51 having a relatively high voltage among the plurality of battery cells (#1 to #N).

[0158] Assuming that the SOC of the battery module 50 is above an appropriate level, it can be said that the higher the voltage of a battery cell among the multiple battery cells (#1 to #N), the more likely it is to be a degraded cell D-Cell compared to other battery cells.

[0159] From a corresponding perspective, when the SOC of the battery module 50 is lower than the optimum level, the battery cell 51 having a relatively higher voltage is more likely to be a normal cell N-Cell than other battery cells.

[0160] Taking these points into consideration, the reference processing unit 170 may set the reference SOC as a value according to the overall behavior characteristics of the battery module 50.

[0161] When the current SOC of the battery module 50 is equal to or greater than the reference SOC, the control unit 140 may control the balancing process for the degraded cell D-Cell to be performed.

[0162] Meanwhile, when the current SOC of the battery module 50 is lower than the reference SOC, the control unit 140 may deactivate the balancing process for both the degraded cell D-Cell and the normal cell N-Cell.

[0163] If the balancing process is controlled to be performed differentially in this way, not only the problem of the energy stored in the normal cell N-Cell being unnecessarily consumed repeatedly, resulting in the battery module 50's available capacity not being fully used as a driving source, but also various problems caused by this, such as performance degradation, shortened lifespan, and overcharging, can be resolved.

[0164] Referring to FIG. 14, in the first SOC section (section 1), the SOC of the battery module 50 is equal to or lower than the reference SOC (Z R ) or more, and the second SOC section (section 2) corresponds to a region where the SOC of the battery module 50 is less than the reference SOC (ZR).

[0165] The first SOC section (section 1) can be estimated as a region where the influence of the degraded cell D-Cell is relatively large. Therefore, the control unit 140 can control the balancing processing unit 130 to activate the balancing process for the degraded cell D-Cell during the time period DA from time Ta to time Tb corresponding to the first SOC section (section 1).

[0166] The second SOC section (section 2) may correspond to a region where the influence of the normal cell N-Cell is relatively large. Therefore, the control unit 140 may control the balancing processing unit 130 so that the balancing process is not performed on all of the battery cells (#1 to #N) during the time period DI from time Tb to time Tc corresponding to the second SOC section (section 2).

[0167] FIG. 4 is a block diagram showing a schematic configuration of the reference processing unit 170 shown in FIG. 3, and FIG. 10 is a flow chart to be referred to in order to explain the process of determining the reference SOC.

[0168] Referring to FIG. 4, the reference processing unit 170 may include a SOC information recording unit 171, a statistical processing unit 173, a reference setting unit 175, and a SOH calculation unit 177.

[0169] Every time a charging process of the battery module 50 is performed, the SOC information recording unit 171 may, in conjunction with the state monitoring unit 120, map a first SOC, which is the SOC of the battery module 50 at the start of the charging process, and a second SOC, which is the SOC of the battery module 50 at the end of the charging process, to the number of the charging process, and record the mapped data. In this way, the first SOC time series data and the second SOC time series data may be recorded in the SOC information recording unit 171.

[0170] The first SOC time-series data includes first start SOC to (k-1)th start SOC indicating the SOC of the battery module 50 at the start of each of the first to (k-1)th charging processes previously performed on the battery module 50. k is an index indicating the number of the latest charging process and is a natural number equal to or greater than 2. That is, k is incremented by 1 each time a new charging process is performed after the previous charging process on the battery module 50 is completed.

[0171] The second SOC time-series data includes a first ending SOC to a (k-1)th ending SOC indicating the SOC of the battery module 50 at the end of each of the first charging process to the (k-1)th charging process.

[0172] In step S1010 , the statistical processing unit 173 acquires the first SOC time series data and the second SOC time series data from the SOC information recording unit 171 .

[0173] In step S1020, the statistical processing unit 173 may extract the (kj)th start SOC through the (k-1)th start SOC from the first SOC time series data. The statistical processing unit 173 may also extract the (kj)th end SOC through the (k-1)th end SOC from the second SOC time series data, where j is a reference number.

[0174] The reference number (j) may be a predetermined natural number equal to or greater than 1. Alternatively, the statistical processing unit 173 may determine the reference number (j) based on the SOH of the battery module.

[0175] In step S1030, the statistical processing unit 173 may calculate an SOC statistic equal to the average value of the (kj)th start SOC to the (k-1)th start SOC and the (kj)th end SOC to the (k-1)th end SOC. The SOC statistic may be used to calculate a reference SOC to be applied to the period from the end of the (k-1)th charging process to the start of the (k+1)th charging process.

[0176] In step S1040 , the reference setting unit 175 determines a reference SOC based on the SOC statistics calculated by the statistical processing unit 173 .

[0177] 10 may be configured to be applied recursively depending on whether a termination condition is satisfied, etc. Depending on the embodiment, the step of checking whether a termination condition is satisfied (S1060) may be omitted.

[0178] Each time a new charging process is completed, the statistical processing unit 173 may update the first SOC time series data, the second SOC time series data, and the SOC statistical values ​​used in the previous charging process.

[0179] For example, if the current charging process is the 31st charging process (i.e., k=31), 30 first SOCs and 30 second SOCs from the first to 30th charging processes have already been recorded in the SOC information recording unit 171. The statistical processing unit 173 may calculate an SOC statistic for the current charging process based on at least one of the 30 first SOCs and at least one of the 30 second SOCs.

[0180] In an embodiment, the statistical processing unit 173 may calculate the SOC statistics by selectively using only S (1 to less than k) first SOCs and second SOCs in reverse order based on the current charging process. For example, if k=31 and S=5, the statistical processing unit 173 may calculate the SOC statistics for the current charging process based on five first SOCs and five second SOCs obtained from the 26th to 30th charging processes.

[0181] According to this embodiment, the SOC statistics are calculated using recent results, so that the past charging and discharging patterns of the battery modules 50 can be more effectively reflected in the differential execution of the balancing process.

[0182] For example, the SOC statistical value may be an average value of S first SOCs and S second SOCs. The reference setting unit 175 may determine a reference SOC equal to the SOC statistical value or equal to a value obtained by multiplying the SOC statistical value by a correction factor. The correction factor may be a predetermined constant or an adjustable value based on the SOH of the battery module 50.

[0183] 15 is a diagram used to explain the differential balancing process when the reference SOC is 80%. In FIG. 15, the SOC swing range is 60% to 100%, and the reference SOC is 80%, which is in the middle of the SOC swing range.

[0184] Although the embodiment shown in FIG. 15 does not exactly correspond to the above-described embodiment in which the balancing process is performed differentially through calculation and comparison of the voltage values ​​(electrical characteristics) of the degraded cell D-Cell and the normal cell N-Cell, the methodology using the SOC value of the battery module 50 as described above inherently reflects the behavioral characteristics of the degraded cell D-Cell and the normal cell N-Cell, and therefore the two can provide results that correspond to each other.

[0185] Meanwhile, the SOH calculation unit 177 may be configured to calculate the SOH of the battery cell 51 and / or the battery module 50 using the electrical characteristics of the battery cell 51 or the battery module 50 input from the status monitoring unit 120, information about the durability or lifespan of the recorded battery cell 51, etc.

[0186] The SOH is a type of information indicating the degree of deterioration, and as the degree of deterioration increases, the rate of change in electrical characteristics may accelerate due to an increase in internal resistance, etc.

[0187] Therefore, the reference setting unit 175 may determine the reference SOC further based on the SOH of the battery module 50. As an example, the reference setting unit 175 may determine a correction factor corresponding to the current SOH of the battery module 50 based on a predetermined negative correspondence between the SOH and the correction factor, and then determine the reference SOC by multiplying the SOC statistical value by the determined correction factor. Accordingly, the correction factor increases as the SOH of the battery module 50 decreases. As a result, even if the SOC statistical value is the same, the reference SOC increases as the SOH of the battery module 50 decreases.

[0188] As described above, by determining the reference SOC by reflecting the SOH of the battery module 50, it is possible to more precisely distinguish the interval in which the cell state parameters of the degraded cell D-Cell are higher than the cell state parameters of the normal cell N-Cell, and the efficiency of the differential balancing process can also be improved.

[0189] In addition to the battery module 50 and the battery management device 100, the battery pack 10 may further include various components, such as a BMS (Battery Management System), bus bars, a pack case, a relay, a current sensor, and other battery pack components known at the time of filing of the present invention.

[0190] The battery management system 100 may be included in an electric vehicle. That is, the electric vehicle according to the present invention may include the above-described battery management system 100 or a battery pack including the same. Furthermore, the electric vehicle according to the present invention may further include various other components such as a vehicle body, a motor, an ECU (Electronic Control Unit), etc. in addition to the battery management system 100 and the battery pack.

[0191] Fig. 16 is a diagram referred to for schematically explaining an example of the balancing processing unit shown in Fig. 1 and Fig. 3. To facilitate understanding, Fig. 16 also shows the configuration of the balancing processing unit 130, as well as the coupling relationship between the battery module 50 and the balancing processing unit 130.

[0192] Referring to FIG. 16, the balancing processor 130 may include a plurality of buck balancing circuits (D#1 to D#N).

[0193] The control unit 140 is operatively coupled to the plurality of back-balancing circuits (D#1 to D#N) so as to be able to output a control signal to each of the plurality of back-balancing circuits (D#1 to D#N).

[0194] The control signal output from the control unit 140 to each of the back-balancing circuits (D#1 to D#N) may be a PWM (Pulse Width Modulation) signal in which a high-level voltage and a low-level voltage are alternately repeated.

[0195] A plurality of back-balancing circuits (D#1 to D#N) are provided in a one-to-one correspondence with a plurality of battery cells (#1 to #N). That is, where i is a natural number less than or equal to N, a back-balancing circuit D#i is provided for selectively performing a balancing process for battery cell #i.

[0196] The back-balancing circuit D#i may include a balancing switch SW and a resistor R. That is, the back-balancing circuit D#i includes a series circuit of the balancing switch SW and the resistor R. The back-balancing circuit D#i is connected in parallel to the battery cell #i.

[0197] The balancing switch SW may be turned on in response to a high-level voltage of the control signal from the control unit 140. The balancing switch SW may be turned off in response to a low-level voltage of the control signal from the control unit 140.

[0198] While the balancing switch SW is turned on, a closed circuit including the back-balancing circuit D#i and the battery cell #i is formed, and current flows through the closed circuit.

[0199] If the balancing switch SW of the back-balancing circuit D#i is turned on during a pause period (e.g., from time t1 to time t2 in FIG. 14) when both charging and discharging of the battery module 50 are stopped, the energy stored in the battery cell #i is consumed by the back-balancing circuit D#i, and the cell state parameter of the battery cell #i gradually decreases.

[0200] If the balancing switch SW of the back-balancing circuit D#i is turned on during the charging period of the battery module 50 (for example, from time Ta to time t1 in FIG. 14), the charging current of the battery module 50 is distributed between the battery cell #i and the back-balancing circuit D#i. Therefore, the charging speed of the battery cell #i slows down.

[0201] If the balancing switch SW of the back-balancing circuit D#i is turned on during the discharge period of the battery module 50 (for example, from time t2 to time Tb in FIG. 14), the battery cell #i may be additionally discharged by the back-balancing circuit D#i in addition to the discharge current of the battery module 50. Therefore, the discharge rate of the battery cell #i increases.

[0202] <Balancing process for only degraded cells among normal cells and degraded cells> Let us assume that battery cell #1 is a degraded cell D-Cell and battery cell #2 is a normal cell N-Cell. Then, the reference SOC (Z RDuring a period (e.g., from time Ta to time Tb in FIG. 14) corresponding to the SOC range above, the balancing switch SW of the back-balancing circuit D#1 provided to battery cell #1 maintains a turned-on state, while the balancing switch SW of the back-balancing circuit D#2 provided to battery cell #2 maintains a turned-off state. That is, the balancing processes for battery cell #1 and battery cell #2 are performed differentially.

[0203] During the charging period (for example, from time Ta to time t1 in FIG. 14), only the charging rate of battery cell #1 decreases among battery cell #1 and battery cell #2.

[0204] During the rest period (for example, from time t1 to time t2 in FIG. 14), only the battery cell #1 of the battery cells #1 and #2 is discharged.

[0205] During the discharge period (for example, from time t2 to time Tb in FIG. 14), the discharge rate of battery cell #1 is faster than the discharge rate of battery cell #2.

[0206] As a result, by performing the differential balancing process during the period from time Ta to time Tb, the cell state parameters of battery cell #1 as the degraded cell D-Cell and the cell state parameters of battery cell #2 as the normal cell N-Cell can be effectively equalized.

[0207] <Balancing process for only normal cells among normal and degraded cells> Let us assume that battery cell #1 is a degraded cell D-Cell and battery cell #2 is a normal cell N-Cell. Then, the reference SOC (Z RDuring a period (e.g., from time Tb to time Tc in FIG. 14) corresponding to the SOC range below, the balancing switch SW of the back-balancing circuit D#1 provided to battery cell #1 maintains a turned-off state, while the balancing switch SW of the back-balancing circuit D#2 provided to battery cell #2 maintains a turned-on state. That is, the balancing processes for battery cell #1 and battery cell #2 are performed differentially.

[0208] During the discharge period (eg, from time Tb to time t3 in FIG. 14), the discharge rate of battery cell #2 is accelerated by back-balancing circuit D#2.

[0209] During the rest period (for example, from time t3 to time t4 in FIG. 14), only battery cell #2 of battery cell #1 and battery cell #2 is discharged.

[0210] During the charging period (for example, from time t4 to time Tc in FIG. 14), the charging rate of battery cell #2 out of battery cell #1 and battery cell #2 is reduced by back-balancing circuit D#2.

[0211] As a result, by performing the differential balancing process during the period from time Tb to time Tc, the cell state parameters of battery cell #1 as the degraded cell D-Cell and the cell state parameters of battery cell #2 as the normal cell N-Cell can be effectively equalized.

[0212] Figure 17 is a diagram referred to for schematically explaining another example of the balancing processor shown in Figures 1 and 3. To facilitate understanding, Figure 17 also shows the configuration of the balancing processor 130, as well as the coupling relationship between the battery module 50 and the balancing processor 130.

[0213] In contrast to the balancing processing unit 130 shown in FIG. 16, the balancing processing unit 130 shown in FIG. 17 may include a plurality of boost balancing circuits (U#1 to U#N).

[0214] The control unit 140 is operatively coupled to the plurality of boost balancing circuits (U#1 to U#N) so as to be able to output a control signal to each of the plurality of boost balancing circuits (U#1 to U#N).

[0215] A plurality of boost balancing circuits (U#1 to U#N) are provided in a one-to-one correspondence with a plurality of battery cells (#1 to #N), i.e., where i is a natural number less than or equal to N, a boost balancing circuit U#i is provided for selectively performing a balancing process for battery cell #i.

[0216] The boost balancing circuit U#i may be a DC voltage source, such as a DC-DC converter.

[0217] The boost balancing circuit U#i responds to a control signal from the control unit 140 to supply charging power to the battery cell #i during operation.

[0218] If the boost balancing circuit U#i operates during the discharge period of the battery module 50 (for example, from time Tb to time t3 in FIG. 14), the discharge power of the battery cell #i is supplemented by the charging power supplied from the boost balancing circuit U#i, thereby slowing down the discharge rate of the battery cell #i.

[0219] If the boost balancing circuit U#i operates during a rest period of the battery module 50 (for example, from time t3 to time t4 in FIG. 14), the cell state parameter of the battery cell #i gradually increases.

[0220] If the boost balancing circuit U#i operates during the charging period of the battery module 50 (for example, from time t4 to time Tc in FIG. 14), the battery cell #i can be additionally charged by the boost balancing circuit U#i in addition to the charging current of the battery module 50. Therefore, the charging speed of the battery cell #i increases.

[0221] <Balancing process for only degraded cells among normal cells and degraded cells> Let us assume that battery cell #1 is a degraded cell D-Cell and battery cell #2 is a normal cell N-Cell. Then, the reference SOC (Z R During a period corresponding to the SOC range below (e.g., from time Tb to time Tc in FIG. 14), the boost balancing circuit U#1 provided to battery cell #1 operates, while the boost balancing circuit U#2 provided to battery cell #2 ceases to operate.

[0222] During the discharge period (for example, from time Tb to time t3 in FIG. 14), the discharge rate of only the battery cell #1 decreases among the battery cell #1 and the battery cell #2.

[0223] During the pause period (for example, from time t3 to time t4 in FIG. 14), only the battery cell #1 of the battery cell #1 and the battery cell #2 is charged independently.

[0224] During the charging period (for example, from time t4 to Tc in FIG. 14), the charging rate of battery cell #1 is faster than the charging rate of battery cell #2.

[0225] As a result, by performing the differential balancing process during the period from time Tb to time Tc, the cell state parameters of battery cell #1 as the degraded cell D-Cell and the cell state parameters of battery cell #2 as the normal cell N-Cell can be effectively equalized.

[0226] <Balancing process for only normal cells among normal and degraded cells> Let us assume that battery cell #1 is a degraded cell D-Cell and battery cell #2 is a normal cell N-Cell. Then, the reference SOC (Z RDuring a period (e.g., from time Ta to time Tb in FIG. 14) corresponding to an SOC range above 1 / 2, the boost balancing circuit U#1 provided to battery cell #1 does not operate, while the boost balancing circuit U#2 provided to battery cell #2 operates.

[0227] During the charging period (eg, from time Ta to time t1 in FIG. 14), the charging rate of battery cell #2 is accelerated by boost balancing circuit U#2.

[0228] During the pause period (for example, from time t1 to time t2 in FIG. 14), only battery cell #2 of battery cell #1 and battery cell #2 is charged independently.

[0229] During the discharge period (for example, from time t2 to time Tb in FIG. 14), the discharge rate of only battery cell #2 out of battery cell #1 and battery cell #2 is reduced by boost balancing circuit U#2.

[0230] As a result, by performing the differential balancing process during the period from time Ta to time Tb, the cell state parameters of battery cell #1 as the degraded cell D-Cell and the cell state parameters of battery cell #2 as the normal cell N-Cell can be effectively equalized.

[0231] On the other hand, the balancing processor 130 may include both the back balancing circuits (D#1 to D#N) according to FIG. 16 and the boost balancing circuits (U#1 to U#N) according to FIG.

[0232] Assume that battery cell #1 is a degraded cell D-Cell and battery cell #2 is a normal cell N-Cell.

[0233] Then, the standard SOC (Z RAt least temporarily during the period from time Ta to time Tb corresponding to the SOC range above, the balancing switch SW of the back balancing circuit D#1 provided to battery cell #1 can be controlled to a turned-on state, and the boost balancing circuit U#2 provided to battery cell #2 can be controlled to an operating state.

[0234] Reference SOC(Z R ) At least temporarily during the period from time Tb to time Tc corresponding to the following SOC range, the boost balancing circuit U#2 provided to battery cell #1 can be controlled to an operating state, and the balancing switch SW provided to battery cell #2 can be controlled to a turned-on state.

[0235] The balancing process using the back-balancing circuits (D#1 to D#N) can be called a back-balancing process, a passive balancing process, or a first balancing process.

[0236] The balancing process using the boost balancing circuits (U#1 to U#N) may be referred to as a boost balancing process, an active balancing process, or a second balancing process.

[0237] The above-described embodiments of the present invention may be realized not only by an apparatus and a method, but also by a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such realization would be easily achievable by a person skilled in the art from the description of the above-described embodiments.

[0238] As described above, the present invention has been described using limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims.

[0239] Furthermore, the present invention described above is susceptible to various substitutions, modifications, and alterations by a person having ordinary knowledge in the technical field to which the present invention pertains, within the scope that does not deviate from the technical concept of the present invention, and is not limited to the above-described embodiments and the accompanying drawings, but may be configured by selectively combining all or part of each embodiment for various modifications.

Claims

1. A battery management device for a battery module including a plurality of battery cells, comprising: a state monitoring unit configured to obtain a plurality of cell state parameters indicative of an electrical state of each of the plurality of battery cells; a balancing processing unit configured to execute a balancing process, which is a procedure for selectively discharging or charging each of the plurality of battery cells, in order to suppress variations in the electrical states among the plurality of battery cells; a control unit configured to control the balancing processing unit to perform a balancing process on at least one battery cell among the plurality of battery cells based on the plurality of cell state parameters.

2. a cell classifier configured to classify each of the plurality of battery cells as a degraded cell or a normal cell based on the plurality of cell state parameters; The control unit The battery management device according to claim 1 , configured to control the balancing processing unit so that the balancing process is performed differentially based on cell state parameters of the degraded cells and cell state parameters of the normal cells.

3. The control unit configured to control the balancing processing unit so that the balancing process is performed on the degraded cell when the cell state parameter of the degraded cell is greater than the cell state parameter of the normal cell; The battery management device of claim 2 , wherein the cell state parameter indicates at least one of a voltage and an SOC.

4. The cell classification unit an input unit configured to obtain the plurality of cell state parameters from the state monitor unit; a processing unit configured to calculate a plurality of cell behavior parameters indicating behavior characteristics of the electrical states of the individual battery cells based on the plurality of cell state parameters; 3. The battery management device of claim 2, further comprising: a selection unit configured to classify each of the plurality of battery cells as the degraded cell or the normal cell based on relative differences between the plurality of cell behavior parameters.

5. the plurality of cell behavior parameters include rates of change of the plurality of cell state parameters; The cell classification unit The battery management device of claim 4, wherein each battery cell mapped to n (n is a natural number greater than or equal to 1) cell behavior parameters that are ranked in the top order of magnitude among the plurality of cell behavior parameters is classified as a degraded cell.

6. the plurality of cell behavior parameters include rates of change of the plurality of cell state parameters; The cell classification unit 5. The battery management device of claim 4, wherein each battery cell that satisfies both a cell behavior parameter during a charging process of the battery module that is equal to or greater than a first reference value and a cell behavior parameter during a discharging process of the battery module that is equal to or greater than a second reference value is selected as the degraded cell.

7. The state monitoring unit The battery module is configured to acquire an SOC of the battery module as a module status parameter indicating an electrical status of the battery module; The control unit 3. The battery management device according to claim 2, wherein the balancing processing unit is controlled so that the balancing process is performed on the degraded cells on the condition that the module state parameter is equal to or greater than a reference SOC while the battery module is being charged.

8. an SOC information recording unit configured to record the first SOC time-series data and the second SOC time-series data; a statistical processing unit configured to calculate an SOC statistical value based on the first SOC time series data and the second SOC time series data; a reference setting unit configured to set the reference SOC similarly to the SOC statistical value; the first SOC time-series data includes first to (k-1)th starting SOCs indicating the SOCs of the battery module at respective start times of first to (k-1)th charging processes previously performed on the battery module; the second SOC time-series data includes first to (k-1)th end SOCs indicating the SOCs of the battery module at respective end points of the first to (k-1)th charging processes; The battery management device according to claim 7 , wherein k is a natural number equal to or greater than 2.

9. The statistical processing unit The battery management device according to claim 8 , configured to calculate the SOC statistic further based on an SOH of the battery module.

10. The statistical processing unit determining a reference number based on the SOH of the battery module; extracting a (k-j)th starting SOC to a (k-1)th starting SOC from the first SOC time series data; extracting a (k-j)th ending SOC to a (k-1)th ending SOC from the second SOC time series data; The SOC statistical value is calculated to be equal to an average value of the (k-j)th starting SOC to the (k-1)th starting SOC and the (k-j)th ending SOC to the (k-1)th ending SOC, The battery management device of claim 9 , wherein j is the reference number.

11. A battery pack comprising the battery management device according to any one of claims 1 to 10.

12. An electric vehicle comprising the battery pack of claim 11.

13. A battery management method executable by a battery management device according to any one of claims 1 to 10, comprising: The state monitoring unit acquires the plurality of cell state parameters indicating the electrical states of the plurality of battery cells; a step in which the control unit controls the balancing processing unit to perform the balancing process on at least one battery cell among the plurality of battery cells based on the plurality of cell state parameters in order to suppress variations in the electrical states among the battery cells.

14. The step of controlling the balancing processing unit includes: classifying each of the plurality of battery cells as a degraded cell or a normal cell based on the plurality of cell condition parameters; 14. The battery management method of claim 13, further comprising: controlling the balancing processing unit so that the balancing process is performed differentially based on cell state parameters of the degraded cells and cell state parameters of the normal cells.

15. The step of controlling the balancing processing unit includes: acquiring an SOC of the battery module as a module status parameter indicating an electrical status of the battery module; and controlling the balancing processing unit to perform the balancing process on the degraded cells on condition that the module state parameter is equal to or greater than a reference SOC during charging of the battery module.

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