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 individual battery cells according to 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 all the contents disclosed in the specifications and drawings of those applications are incorporated herein.

Background Art

[0003] As the demand for portable electronic products such as notebook computers, video cameras, and mobile phones that use electricity as a driving source has rapidly increased, and as mobile robots, electric bicycles, electric carts, electric vehicles, etc. have been widely commercialized, research on high-performance secondary batteries that can be repeatedly charged and discharged has been actively conducted.

[0004] Commercially available rechargeable secondary batteries (hereinafter also referred to as "battery cells" or "cells") include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among them, lithium secondary batteries have almost no memory effect compared to nickel-based secondary batteries, so they can be freely charged and discharged, have the advantage of a very low self-discharge rate, and also have the characteristics of high energy density and high operating voltage. Therefore, they have been intensively studied compared to other types of secondary batteries and are more widely applied to actual products.

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

[0006] In this case, battery modules in which multiple electrically connected battery cells are housed together inside a module case are primarily used. Furthermore, when high power or large capacity is required, battery packs comprising multiple battery modules electrically connected in series and / or parallel may also be used.

[0007] Such battery modules or battery packs (hereinafter collectively referred to as "batteries") are devices that provide power, and therefore energy efficiency is a critical issue. Accordingly, various efforts are focused on increasing energy density, including methods for realizing electrode assemblies as multiple unit stacks, methods for improving the physical properties of battery cells, and methods for increasing electrochemical efficiency.

[0008] From this perspective, a balancing process is applied to optimize battery performance by appropriately using charging or discharging circuits to control the electrical characteristics (voltage, SOC, etc.) of multiple battery cells contained in the battery uniformly (so that they fall within an appropriate error range).

[0009] In multiple battery cells, differences in individual dynamic states, such as internal resistance, material properties, human error due to the operating environment, cooling efficiency, and capacity, can result in non-uniform electrical characteristics (e.g., voltage or state of charge).

[0010] When variations in electrical characteristics occur in this way, the actual available resources are not used in an optimized manner, resulting in a problem where the performance of the battery module is lower than the actual available capacity and available output. Furthermore, if at least one battery cell reaches its peak electrical characteristics before the others, the charging process will be terminated before the other battery cells with remaining internal capacity can finish charging, thus severely limiting the overall charge of the battery module.

[0011] To give 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 become unable to discharge (supply power) as well as charge (store energy).

[0012] Furthermore, if the battery continues to be used without properly correcting the voltage deviation, the voltage deviation will worsen, which will not only further degrade the battery's performance but also potentially cause safety problems such as fire due to overcharging.

[0013] The balancing process, as a way to resolve these problems, continuously controls multiple battery cells to maintain a uniform electrical state, thereby providing benefits such as maintaining stable battery performance, increasing service life, and improving output efficiency.

[0014] Balancing processes include methods such as charging battery cells with relatively low electrical characteristics through a separate power source, and transferring energy from battery cells with relatively high electrical characteristics to battery cells with relatively low electrical characteristics. However, for reasons such as 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, this type of balancing is performed based solely on formal values ​​that are measured or calculated externally, such as the voltage of the battery cells, without considering the actual characteristics of the battery cells.

[0016] For example, in the case of a battery cell that is highly degraded due to increased internal resistance, its electrical characteristics will be relatively lower than other battery cells during discharge. However, even in this case, conventional balancing processes may cause the problem of unnecessarily consuming available resources by discharging normal battery cells that have high electrical characteristics.

[0017] As mentioned above, balancing is performed continuously according to the current state of the battery, so these problems occur repeatedly with battery use, and because degradation accelerates over time, the cycle of the balancing process is further shortened. This not only exacerbates energy waste and a decline in driving performance, but also has a serious negative impact on the battery life itself. [Overview of the Initiative] [Problems that the invention aims to solve]

[0018] The present invention was devised to solve the above-mentioned 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 of the multiple battery cells, taking into account not only the electrical state of each individual battery cell included in the battery module, but also the behavioral characteristics of each individual battery cell.

[0019] The technical problems that this invention aims to solve are not limited to those described above, and other problems can be clearly understood by an ordinary person from the following description of the invention. [Means for solving the problem]

[0020] A battery management device according to one aspect of the present invention is provided for a battery module including a plurality of battery cells. The battery management device includes: a state monitoring unit configured to acquire a plurality of cell state parameters indicating the electrical state of each of the plurality of battery cells; a balancing processing unit configured to perform 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 battery cells; and a control unit configured to control the balancing processing unit so that the balancing process is performed for at least one of the plurality of battery cells based on the plurality of cell state parameters.

[0021] The battery management device may further include a cell classification unit that classifies each of the plurality of battery cells as either a degraded cell or a normal cell based on a plurality of cell state parameters. The control unit may control 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.

[0022] The control unit may control the balancing processing unit so that the balancing process is performed for the degraded cell if the cell state parameter of the degraded cell is greater than the cell state parameter of the normal cell. The cell state parameter may represent at least one of voltage and SOC (State of Charge).

[0023] The cell classification unit may include an input unit configured to acquire a plurality of cell state parameters from the state monitoring unit; a calculation processing unit configured to calculate a plurality of cell behavior parameters that indicate the behavioral characteristics of the electrical state of each 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 either a degraded cell or a normal cell based on the relative differences between the cell behavior parameters.

[0024] The cell behavior parameter may include a change rate of the cell state parameter. The cell classification unit may be configured to classify each battery cell mapped to n (n is a natural number of 1 or more) cell behavior parameters corresponding to the top in descending order among the plurality of cell behavior parameters as the degraded cell.

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

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

[0027] The control unit may control the balancing processing unit so that the balancing process for the degraded cell is executed on the condition that the module state parameter is equal to or greater than the reference SOC during charging of the battery module.

[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 an SOC statistical value based on the first SOC time series data and the second SOC time series data, and a reference setting unit configured to set the reference SOC in the same manner as the SOC statistical value.

[0029] The first SOC time series data may include a first start SOC to the (k-1)th start SOC, which shows the SOC of the battery module at the start of each of the first to (k-1)th charging processes performed on the battery module in the past. The second SOC time series data may include a first end SOC to the (k-1)th end SOC, which shows the SOC of the battery module at each of the end of the first to (k-1)th charging processes. 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 based on the 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 the (kj)th start SOC to the (k-1)th start SOC from the first SOC time series data. The statistical processing unit may be configured to extract the (kj)th end SOC to the (k-1)th end SOC from the second SOC time series data. The statistical processing unit may be configured to calculate the SOC statistic value 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. 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] A battery management method according to yet another aspect of the present invention can be performed by the battery management device. The battery management method includes the steps of: the state monitoring unit acquiring a plurality of cell state parameters indicating the electrical state of each of the plurality of battery cells; and the control unit controlling the balancing processing unit so that the balancing process is performed for at least one of 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 steps of controlling the balancing processing unit may include: classifying each of the plurality of battery cells as a degraded cell or a normal cell based on a plurality of the cell state parameters; and controlling the balancing processing unit so that the balancing process is performed differently 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 the step of acquiring the State of Charge (SOC) of the battery module as a module state parameter indicating the electrical state of the battery module, and the step of controlling the balancing processing unit so that the balancing process for the degraded cell is executed 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, by using the time-series changes in the electrical state and / or behavioral characteristics of individual battery cells, it is possible to identify operating conditions that do not induce a weakening of the driving performance of the battery module, and to selectively perform a balancing process on at least one of the battery cells while the identified operating conditions are met.

[0038] Furthermore, 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 by organically combining the classification results with the control operation for the balancing process, the performance of the battery module can be improved.

[0039] Furthermore, according to one aspect of the present invention, by selectively allowing the execution of a balancing process on at least one battery cell, taking into account the difference between the behavioral characteristics of a normal cell and the behavioral characteristics of a degraded cell, it is possible to effectively resolve not only the problem of unnecessary limitation of the usable capacity and output of normal cells, but also problems such as the solidification of performance degradation or shortening of lifespan.

[0040] Furthermore, according to one aspect of the present invention, statistical values ​​for the swing range of the State of Charge (SOC), which is the main operating range of the battery module, can be calculated based on the charging and / or discharging history of the battery module, and these statistical values ​​can be used as a kind of standard for differential execution of the balancing process, thereby improving the efficiency of the balancing process.

[0041] Furthermore, according to one aspect of the present invention, the balancing process can be performed on only battery cells classified as either degraded cells or normal cells. When the balancing process is performed on only degraded cells instead of normal cells, there is an advantage in that the state deviation between normal and degraded cells is quickly eliminated. When the balancing process is performed on only normal cells instead of degraded cells, the charging and discharging of degraded cells due to the balancing process is reduced accordingly, which helps to equalize the life deviation between normal and degraded cells.

[0042] In addition, the present invention can produce a variety of other effects. These will be described in each embodiment, but effects that can be easily inferred by those skilled in the art will not be described.

[0043] The following drawings accompanying this specification illustrate preferred embodiments of the invention and, together with the detailed description of the invention, serve to further illustrate the technical idea of ​​the invention; therefore, the invention should not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0044] [Figure 1] This is a block diagram schematically showing the configuration of a battery pack according to one embodiment of the present invention. [Figure 2] This diagram schematically shows the configuration of the cell classification unit shown in Figure 1. [Figure 3] This is a block diagram schematically showing the configuration of a battery pack according to another embodiment of the present invention. [Figure 4] Figure 3 is a block diagram that schematically shows the configuration of the reference processing unit. [Figure 5] Figure 1 is a flowchart illustrating an example of a battery management method that can be performed by the battery management device shown. [Figure 6] This flowchart shows another example of a battery management method that can be performed by the battery management device shown in Figure 1. [Figure 7] This flowchart shows yet another example of a battery management method that can be performed by the battery management device shown in Figure 1. [Figure 8] This flowchart illustrates the process of classifying multiple battery cells into either a normal or degraded cell. [Figure 9] Figure 3 is a flowchart illustrating the processes that can be performed by the battery management device shown. [Figure 10] This is a flowchart used to explain the process of determining the standard SOC. [Figure 11] This figure is referenced to illustrate the change in the State of Charge (SOC) of a battery cell over time. [Figure 12] This diagram is used to illustrate the behavioral characteristics of normal cells and degraded cells. [Figure 13] This is an enlarged view of the dotted line area shown in Figure 12. [Figure 14] This diagram is referenced to illustrate the process of performing a differential balancing process for degraded and normal cells according to the baseline SOC. [Figure 15] This diagram is referenced to illustrate the differential balancing process performed when the baseline SOC is 80%. [Figure 16] These figures are referenced to schematically illustrate an example of the balancing processing unit shown in Figures 1 and 3. [Figure 17] These figures are referenced to schematically illustrate other examples of the balancing processing unit shown in Figures 1 and 3. [Modes for carrying out the invention]

[0045] Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Prior to this, terms and words used herein and in the claims shall not be interpreted in their usual and dictionary sense, but rather in a sense and concept that corresponds to the technical idea of ​​the present invention, in accordance with the principle that the inventor himself may appropriately define the concept of terms in order to best describe the invention.

[0046] Therefore, the embodiments and configurations shown in the drawings described herein represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the present invention. It should be understood that there are various equivalents and modifications that can be substituted for these at the time of filing this application.

[0047] Terms that include ordinal numbers, such as "1st," "2nd," etc., are used to distinguish one of several components from other components, and these terms do not limit the components themselves.

[0048] Throughout the specification, when a part of it "includes" a component, this does not exclude other components unless otherwise specified, but rather means that it may include other components. Furthermore, terms such as "[control unit]" in the specification mean a unit that processes at least one function or operation, and can be embodied in hardware, software, or a combination of hardware and software.

[0049] Furthermore, when a part of the specification is described as being "connected" to another part, this includes not only "direct connections" but also "indirect connections" mediated by other elements.

[0050] Figure 1 is a schematic block diagram showing the configuration of a battery pack according to one embodiment of the present invention, and Figure 5 is a flowchart showing an example of a battery management method that can be performed by the battery management device shown in Figure 1.

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

[0052] The battery module 50 includes multiple battery cells (#1 to #N). N is a natural number greater than or equal to 2 and may represent the total number of battery cells included in the battery module 50. The multiple battery cells (#1 to #N) may be electrically connected in series with each other. When describing the common features of the multiple battery cells (#1 to #N), the battery cells are denoted by reference numeral 51. In Figure 1, the battery cell 51 is shown as a single unit, but this is merely an example, and depending on the embodiment, the battery cell 51 may be a cell assembly formed by grouping multiple cell units connected in parallel with each other.

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

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

[0055] In order to ensure stable maintenance and management of electrical characteristics as well as charging and discharging efficiency, it is preferable that multiple battery cells (#1 to #N) be configured to have equivalent levels of performance and specifications.

[0056] The battery management device 100 may include a measurement unit 110, a status 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 device 100 can be realized through the application of various combinations of electronic elements and components such as recording means, arithmetic processing means, and input / output means. Each component of the battery management device 100 shown in Figure 1 may be physically separated, or alternatively, functionally or logically separated.

[0058] In other words, since each component corresponds to a logical component for realizing the technical concept of the present invention, if the functions of the logical configuration of the present invention can be performed even if each component is integrated or separated, it is interpreted as falling within the scope of the present invention. If the components perform the same or similar functions, they are interpreted as falling within the scope of the present invention, regardless of whether their names are the same or whether their configurations are divided or integrated. The same applies to the configurations of the present invention shown in Figures 2 to 4.

[0059] The state monitoring unit 120 calculates multiple cell state parameters that indicate the individual electrical states of multiple battery cells (#1 to #N) and / or module state parameters that indicate the electrical state of the battery module 50 (see S520, Figure 5). The module state parameters are electrical characteristics based on the entire battery module 50 and may depend on the multiple cell state parameters. The module state parameters may be values ​​that represent the multiple cell state parameters. For example, the SOC of the battery module 50 as a module state parameter can be determined in the same way as the average SOC of multiple battery cells (#1 to #N) based on the multiple cell state parameters.

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

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

[0062] In this embodiment, the acquisition period for cell state parameters may be set to be 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 acquisition period for cell state parameters may be pre-recorded in a lookup table.

[0063] According to this embodiment, the more rapidly electricity is used, the more precise information can be interfaced to users, and the efficiency of data processing can be increased by reducing the processing speed and amount of computation in sections where the need for precise information provision is relatively low.

[0064] It is preferable that the cell state parameters and / or module state parameters are generated not only during the charging process in which power is supplied (stored) to the battery module 50 from an external power supply device, but also during the discharge process in which power is supplied to a load such as an electric motor, so that the electrical state or behavioral characteristics of the battery cell 51 can be understood more precisely.

[0065] The balancing processing unit 130 is configured to perform a balancing process on multiple battery cells (#1 to #N) constituting the battery module 50, and may include hardware configurations such as well-known relays (switches), load resistors, and timers. The balancing processing unit 130 may be electrically connected to the battery cells 51 and configured to perform functions such as discharging and / or charging the corresponding battery cells 51 according to control signals. The hardware implementation of the balancing processing unit 130 will be described later with reference to Figures 16 and 17.

[0066] When the module state parameters for the battery module 50 are generated, the control unit 140 executes a procedure (S530) to determine whether the module state parameters satisfy predetermined specific conditions for initiating the balancing process. For example, the specific conditions may be a combination of (i) the module state parameters being equal to or greater than the reference SOC, and (ii) the voltage of a degraded cell being higher than the voltage of a normal cell. As another example, the specific conditions may be a combination of (i) the module state parameters being equal to or less than the 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 so that the balancing process is performed for at least one of the multiple battery cells (#1 to #N) (S540).

[0067] The processes of the present invention described above may be designed to be applied cyclically so that continuous battery management is maintained unless events such as power off, firmware replacement, or fulfillment of previously set termination conditions occur. Depending on the embodiment, the step of checking whether the termination conditions are met (S550) from the method in Figure 5 may be omitted. The termination conditions may be, for example, that the voltage deviation (e.g., the difference between the maximum voltage and the minimum voltage) of a plurality of battery cells (#1 to #N) falls within a predetermined tolerance range.

[0068] When an event requiring balancing occurs, such as the voltage deviation of any battery cell (e.g., #1) among multiple battery cells (#1 to #N) exceeding a reference deviation, the battery management device 100 can proactively determine negative situations where the balancing process might actually cause a decrease in the performance of the battery module 50 or deterioration of the battery cell (e.g., #1), rather than immediately executing the balancing process for the battery cell (e.g., #1).

[0069] The battery management device 100 is configured to perform a balancing process on a battery cell (e.g., #1) only if it is determined that performing the balancing process on that battery cell (e.g., #1) will not result in any negative consequences. Here, the voltage deviation of any battery cell (e.g., #1) may mean the difference between the average voltage value of multiple battery cells (#1 to #N) and the voltage value of the battery cell (e.g., #1).

[0070] Figure 6 is a flowchart illustrating another example of a battery management method that can be performed by the battery management device shown in Figure 1.

[0071] Referring to Figure 6, the status monitoring unit 120 acquires multiple cell status parameters indicating the individual electrical states of multiple battery cells (#1 to #N) (S610). The status monitoring unit 120 can generate and store the individual cell status parameters of multiple battery cells (#1 to #N) through cooperation with the measurement unit 110.

[0072] In this embodiment, the state monitoring unit 120 can directly utilize the cell state parameters measured by the measurement unit 110. However, 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 state monitoring unit 120 may include a hardware configuration to appropriately adjust or filter these components, or it may be equipped with a software algorithm to process them.

[0073] The battery management device 100 is an embodiment that, through a comparison of the electrical state and / or behavioral characteristics of a plurality of battery cells (#1 to #N), classifies battery cells that fall within the normal range (hereinafter referred to as "normal cells") and battery cells that have relatively deteriorated behavioral characteristics (hereinafter referred to as "deteriorated cells") over time, and uses the results to apply a balancing process differently to the plurality of battery cells (#1 to #N).

[0074] Voltage values ​​have the advantage of being measurable or generated with a relatively simple circuit configuration (such as a configuration that measures the voltage difference across the terminals of the battery cell 51), and they also have the characteristic of clearly outwardly representing the intrinsic characteristics of the battery cell 51. Therefore, when used as raw data, it is possible to clearly estimate and select whether or not a cell is degraded.

[0075] From this perspective, the cell state parameters are not particularly limited as long as they can indicate the electrical state of the battery cell 51 as described above, and typically include the voltage value of the battery cell 51.

[0076] If the status monitoring unit 120 acquires the individual cell status parameters (e.g., voltage values) of multiple battery cells (#1 to #N) (S610), the cell classification unit 150 can use the individual voltage values ​​of the multiple battery cells (#1 to #N) to classify each of the multiple battery cells (#1 to #N) of the battery module 50 as either a degraded cell or a normal cell (S620). Embodiments 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 executed 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 state parameters satisfy predetermined specific conditions for initiating the balancing process. Step S630 may be executed on the condition that the module state parameters are equal to or greater than the reference SOC, or that the module state parameters are less than or equal to the reference SOC.

[0079] Figure 14 is a diagram referenced to illustrate the process of performing a differential balancing process for degraded cells and normal cells according to the baseline SOC.

[0080] The control unit 140 can control the balancing process for degraded cells to be executed (S640). For example, if the module state parameter is above the reference SOC, the control unit 140 can control the balancing processing unit 130 (see Figure 16) to execute the balancing process for degraded cells during a time interval in which the voltage of the degraded cells is higher than the voltage of the normal cells (the "DA" interval in Figure 14). As another example, if the module state parameter is below the reference SOC, the control unit 140 can control the balancing processing unit 130 (see Figure 17) to execute the balancing process for degraded cells during a time interval in which the voltage of the normal cells is higher than the voltage of the degraded cells (the "DI" interval in Figure 14).

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

[0082] On the other hand, if the value of step S630 is "no", the balancing processing unit 130 can be controlled so that the balancing process for both degraded cells and normal cells is deactivated. This process can also be configured to be applied recursively, as described above, depending on whether the termination conditions are met. Depending on the embodiment, the step of confirming whether the termination conditions are met (S650) may be omitted.

[0083] Hereinafter, with reference to Figures 2, 7, and 8, a specific embodiment of the present invention that classifies each of multiple battery cells (#1 to #N) into a degraded cell or a normal cell will be described in detail.

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

[0085] After explaining the behavioral characteristics of the battery cell 51 with reference to Figures 11 and 12, the specific functions of the selection unit 155, which organically reflects these behavioral characteristics to select degraded cells and normal cells, will be described in detail later.

[0086] Figure 11 is a diagram referenced to illustrate the change in the State of Charge (SOC) of battery cell 51 over time. The SOC of battery cell 51 may be included as a cell state parameter of battery cell 51.

[0087] Referring to Figure 11, the battery cell 51 exhibits a behavioral characteristic in which its voltage value increases during the charging period (t0~t1). Therefore, the State of Charge (SOC) of the battery cell 51, estimated by applying a functional calculation to the voltage value, also exhibits a behavioral characteristic of increasing.

[0088] After charging is complete (for example, reaching a fully charged state of charge of 100%), the State of Charge (SOC) of the battery cell 51 remains constant during a rest period (t1-t2) when both charging and discharging are stopped, provided that other external factors such as standby current consumption are not considered. Subsequently, during the discharge period (t2-t3) for driving a load (such as an electric motor), the voltage value and SOC of the battery cell 51 exhibit a decreasing (decreasing) behavioral characteristic.

[0089] Once the rest period (t3-t4) following the discharge period (t2-t3) is over, the charging period (t4-t5) begins again through an external power supply means, and the voltage value and state of charge (SOC) of the battery cell 51 rise again during the charging period (t4-t5). These behavioral characteristics of the battery cell 51 are repeated chronologically during the charging, rest, and / or discharging cycles.

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

[0091] For reference, Figure 11 and other figures show that the behavioral characteristics of the battery cell 51 change linearly with time for the sake of explanation, but it goes without saying that the actual behavioral characteristics of the battery cell 51 involve a mixture of linearity and nonlinearity. If the measurement and generation of electrical characteristics are performed intermittently at specific intervals, the results may be discontinuous and differ from those shown in the figures unless post-processing methods such as interpolation are taken into consideration.

[0092] Figure 12 is a reference diagram used to illustrate the behavioral characteristics of a normal cell (N-Cell) and a degraded cell (D-Cell), and Figure 13 is an enlarged view of the dotted line region B shown in Figure 12.

[0093] As mentioned above and shown in Figure 11, both normal cells (N-Cell) and degraded cells (D-Cell) show an increase in voltage during charging and a decrease in voltage during discharging.

[0094] If performance degradation occurs in the battery cell 51 due to aging over time, material properties, or artificial usage environment, the factors and causes of performance degradation will mostly manifest as intrinsic resistance components. As a result, the internal resistance and similar resistance components (collectively referred to as "internal resistance") of the cell in which performance degradation or decline has occurred will increase.

[0095] Battery cell 51, with its relatively increased internal resistance, will experience a relatively higher voltage increase compared to other battery cells 51, even when the same amount of current flows through it, according to general laws regarding the correlation between voltage and current (Ohm's law). In other words, even with a relatively small current, it will achieve a voltage increase at the same level as other battery cells 51.

[0096] As mentioned above, since the State of Charge (SOC) is calculated functionally from the voltage of the battery cell 51, the SOC also exhibits characteristic changes corresponding to changes in voltage.

[0097] From a discharge perspective, discharge is the release of the charge (electric 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 differences in internal resistance.

[0098] Referring to Figure 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 voltage change during the same charging period is relatively larger for the degraded cell D-Cell compared to the normal cell N-Cell.

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

[0100] Although the drawings show the behavioral characteristics of the charging and discharging processes as corresponding (symmetrical), the behavioral 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 load means (electric motor, etc.), as well as the electrochemical properties inherent in charging and discharging, respectively.

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

number

[0102] In the formula, Δt is a predetermined small time interval, 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, during the charging process, SD will have a larger value than SN, and during the discharging process, SD will also have a larger value than SN (based on absolute value).

[0103] In this way, the level of performance degradation 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 change in the voltage value over time (cell behavior parameters).

[0104] Furthermore, the degree or magnitude of degradation of each battery cell (#1 to #N) can be mathematically quantified by comparing the magnitude (absolute value) of the rate of change per unit time of the individual cell state parameters of multiple battery cells (#1 to #N). That is, the multiple battery cells (#1 to #N) can be ranked in descending or ascending order based on their respective cell behavior parameters (corresponding to the degree of degradation).

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

[0106] Figure 7 is a flowchart illustrating yet another example of a battery management method that can be performed by the battery management device shown in Figure 1.

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

[0108] As described above, the cell behavior parameters of any battery cell 51 may include the rate of change per unit time of the cell state parameters of the battery cell 51. In the embodiment, the rate of change per unit time of the State of Electricity (SOC) or the magnitude difference of the SOC, generated through functional processing of the difference values ​​of electrical characteristics, voltage values, etc., at multiple points in time or multiple time intervals may be used as the behavior characteristics.

[0109] Once the cell behavior parameters of the battery cell 51 have been calculated, the selection unit 155 classifies each of the multiple battery cells (#1 to #N) as either 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 less than or equal to the set number (n, a natural number between 1 and N, inclusive), all identified target cells may be classified as degraded cells. If the number of target cells identified in step S730 exceeds the set number (n), step S740 may be executed.

[0111] In step S740, the selection unit 155 sorts the multiple cell behavior parameters that are mapped one-to-one to the multiple target cells identified in step S730 in order of magnitude, and can select each battery cell mapped to the highest number of cell behavior parameters (n) as a degraded cell D-Cell (S740). The remaining battery cells that are not selected as degraded cells D-Cells in step S740 are classified as normal cells.

[0112] The number of settings (n) may be a predetermined constant. Alternatively, the selection unit 155 may determine the number of settings (n) based on environmental information such as battery efficiency, current output characteristics, specifications of the load means (electric motor, etc.), battery cell durability, battery cell usage period, charge / discharge cycle, and SOH. The process described above may also be configured to be applied recursively depending on whether the termination conditions are met, as described above. Depending on the embodiment, the step of confirming whether the termination conditions are met (S750) may be omitted.

[0113] Furthermore, the selection unit 155 may be configured to determine (S730) whether or not there are any battery cells (hereinafter also referred to as "target cells") whose cell behavior parameters (such as the rate of change of cell state parameters per unit time or their absolute value) are equal to or greater than a reference value, and then select at least one of the target cells as a degraded cell D-Cell (S740).

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

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

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

[0117] According to this embodiment, not only can the time interval in which the balancing process is deactivated be optimized, but the energy consumption of the degraded cell D-Cell due to the balancing process can be appropriately limited, thereby maintaining that the overall output performance of the battery module 50 does not deviate significantly from the normal range.

[0118] If each of the multiple battery cells (#1 to #N) is classified as either a normal cell N-Cell or a degraded cell D-Cell, the control unit 140 can control the system so that a balancing process for the degraded cell D-Cell is performed for at least the time interval DA, as shown in Figure 12. The time interval DA is part of the charging period of the battery module 50, and during the time interval DA, the voltage value of the degraded cell D-Cell is greater than or equal to the voltage value of the normal cell N-Cell.

[0119] The control unit 140 controls the system so that the balancing process is not executed even if a voltage deviation occurs during intervals (DI) when 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 interval DI corresponds to the discharge period of the battery module 50.

[0120] On the other hand, if the voltage deviation of all battery cells (#1 to #N) is below the reference deviation, then of course the balancing process will not be performed for any of the battery cells (#1 to #N).

[0121] The battery management device 100 can perform a balancing process differentially by selecting normal cells (N-Cell) and degraded cells (D-Cell) and using their electrical characteristics (voltage values, etc.) and behavioral characteristics. Table 1 below shows an example of operating conditions referenced for performing the balancing process. [Table 1]

[0122] Figure 8 is a flowchart illustrating the process of classifying each of the multiple battery cells (#1 to #N) into either a normal cell (N-Cell) or a degraded cell (D-Cell).

[0123] Referring to Figure 8, when the cell state parameters (e.g., voltage) 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 and other related matters have been described above with reference to Figure 7, so a detailed explanation is omitted here.

[0124] Next, the selection unit 155 may be configured to select a degraded cell D-Cell or the like based on the charging procedure and the discharging procedure, respectively.

[0125] Specifically, the selection unit 155 can rank the battery cells (#1 to #N) by arranging multiple cell behavior parameters, which are mapped one-to-one to multiple battery cells (#1 to #N), in order of magnitude during at least one of the discharge and charge processes.

[0126] The selection unit 155 may be configured to perform the following steps based on multiple cell behavior parameters indicating the behavioral characteristics of each of the multiple battery cells (#1 to #N) input sequentially from the calculation processing unit 153: a process (S830) to confirm the existence of a first target cell, which is a battery cell whose cell behavior parameters acquired during the charging process are equal to or greater than a first reference value; and a process (S840) to confirm the existence of a second target cell, which is a battery cell whose cell behavior parameters (absolute value) acquired during the discharging process are equal to or greater than a second reference value. The cell behavior parameters acquired during the charging process are referred to as the first cell behavior parameters, and the cell behavior parameters acquired during the discharging process are referred to as the second cell behavior parameters. The first reference value may be the average value of the first cell behavior parameters of the multiple battery cells (#1 to #N). The second reference value may be the average value of the second cell behavior parameters of the multiple battery cells (#1 to #N).

[0127] To optimize each reference value, the length of the charging process for determining the first cell behavior parameter and the length of the discharging process for determining the second cell behavior parameter can each be set to be longer than a predetermined reference time.

[0128] Thus, a process to check whether the individual cell behavior parameters of multiple battery cells (#1 to #N) are equal to or greater than a first reference value, based on the charging state, and a process to check whether the individual cell behavior parameters of multiple battery cells (#1 to #N) are equal to or greater than a second reference value, based on the discharging state, can be performed in advance.

[0129] The selection unit 155 can be configured to select a battery cell 51 from among a plurality of battery cells (#1 to #N) whose cell behavior parameters are identified as being above a reference value in both the charging and discharging processes as a degraded cell D-Cell (S850).

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

[0131] On the other hand, if the number of battery cells among the multiple battery cells (#1 to #N) that correspond to both the first target cell and the second target cell exceeds the critical number (m), the selection unit 155 may select only the battery cells that correspond to both the first target cell and the second target cell and that correspond to the critical number (m) as degraded cells D-Cell (S850). In this case, the battery cells that correspond to the critical number (m) can be selected as degraded cells D-Cell in order of the highest 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 and the transient nature of deviations caused by noise signals and the like can be eliminated in advance, thereby improving the overall efficiency and accuracy of the balancing process.

[0133] The critical number (m) can be a predetermined constant. Alternatively, it is preferable to configure the system so that the critical number (m) is variably set based on environmental information such as battery efficiency, current output characteristics, specifications of the load (electric motor, etc.), battery cell durability, battery cell usage period, charge / discharge cycle, and SOH.

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

[0135] The control unit 140 can control the system to intentionally refrain from performing the balancing process for the normal cell N-Cell during time intervals when the voltage of the normal cell N-Cell remains higher than the voltage of the degraded cell D-Cell, while restrictively performing the balancing process for the degraded cell D-Cell only during time intervals when the voltage of the degraded cell D-Cell remains higher than the voltage of the normal cell N-Cell.

[0136] This prevents energy charged to normal cells N-Cells, which have sufficient usable capacity and excellent behavioral characteristics, from being unnecessarily consumed by the balancing process, and effectively resolves the problem that the usable capacity of the battery module 50 is not fully utilized because the State of Charge (SOC) of the battery module 50 is limited early by the behavioral characteristics of degraded cells D-Cells.

[0137] The control unit 140 may be configured to transmit various information and data generated by the above-described process to an external control device 200 or the like, which is installed in an electric vehicle, via 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 via the interface unit 160.

[0138] Furthermore, the cell classification unit 150 or the control unit 140 may be configured to transmit alarm information regarding the need to replace a battery cell (e.g., #1) to the external control device 200 via the interface unit 160 if a battery cell (e.g., #1) is identified as being selected as a degraded cell D-Cell for a specified period of time or more, or repeated more than a specified number of times.

[0139] From this perspective, if identification information of the battery cells 51 constituting the battery module 50 is pre-databased, information that physically identifies the battery cells 51 classified as degraded cells (D-Cells) can also be transmitted to the external control device 200 along with the alarm information.

[0140] Figure 3 is a schematic block diagram showing the configuration of a battery pack according to another embodiment of the present invention, and Figure 9 is a flowchart showing the processes that can be executed by the battery management device shown in Figure 3.

[0141] The battery pack 10 shown in Figure 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 multiple battery cells (#1 to #N) to be performed differently, reflecting statistical values ​​calculated based on a reference SOC or the user's charging and discharging patterns.

[0143] In comparison to the detailed configuration shown in Figure 1, the reference processing unit 170 is replaced by the cell classification unit 150 in Figure 3. However, this is only one embodiment, and the battery management device 100 may be implemented in a form that includes both the reference processing unit 170 and the cell classification unit 150.

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

[0145] In step S910, the status monitoring unit 120 acquires multiple cell status parameters (e.g., voltage values) from the measurement unit 110, which are mapped one-to-one to multiple battery cells (#1 to #N).

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

[0147] In step S930, the control unit 140 may determine whether the current module state parameter (e.g., SOC) is greater than or equal to the reference SOC stored in the reference processing unit 170. If the value in step S930 is "yes", the process proceeds to step S932. If the value in step S930 is "no", it means that the module state parameter is less than the reference SOC. If the value in step S930 is "no", the process proceeds to step S934.

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

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

[0150] In step S940, the control unit 140 can control the balancing processing unit 130 so that a balancing process is performed on at least one battery cell classified as a degraded cell D-Cell among the multiple battery cells (#1 to #N).

[0151] If the process proceeds from step S932 to step S940, the control unit 140 can control the balancing processing unit 130 shown in Figure 16 to execute a balancing process for the degraded cell D-Cell. On the other hand, if the process proceeds from step S934 to step S940, the control unit 140 can control the balancing processing unit 130 shown in Figure 17 to execute a balancing process for the degraded cell D-Cell.

[0152] The process described above can also be configured to be applied recursively, depending on whether the termination conditions are met, as described above. Depending on the embodiment, the step of confirming whether the termination conditions are met (S950) may be omitted.

[0153] In connection with this, in order to classify each of the multiple battery cells (#1 to #N) as either 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 classification. Therefore, the charging process and discharging process performed prior to the cell classification procedure can be called a pre-charging process and a pre-discharging process, respectively.

[0154] As an example, steps S510 in Figure 5, S610 in Figure 6, S710 in Figure 7, S810 in Figure 8, and S910 in Figure 9 can each be performed while at least one of the pre-charging process and pre-discharging process is in progress.

[0155] Furthermore, steps S540 in Figure 5, S640 in Figure 6, and S940 in Figure 9 may be performed in a charging process and / or discharge process that follows a pre-charging process and / or pre-discharging process, respectively.

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

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

[0158] Assuming that the State of Charge (SOC) of battery module 50 is above the appropriate level, the higher the voltage of a battery cell (#1 to #N) among the multiple battery cells, the relatively higher the probability that it is a degraded cell (D-Cell) compared to the other battery cells.

[0159] From a corresponding perspective, if the State of Charge (SOC) of the battery module 50 is lower than the appropriate level, the battery cell 51 with a relatively higher voltage is relatively more likely to be a normal N-Cell compared to other battery cells.

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

[0161] The control unit 140 can control the balancing process for degraded cells (D-Cells) to be performed if the current SOC of the battery module 50 is equal to or greater than the reference SOC.

[0162] On the other hand, if the current SOC of the battery module 50 is less than the reference SOC, the control unit 140 may deactivate the balancing process for both degraded cells (D-Cells) and normal cells (N-Cells).

[0163] By controlling the balancing process to be performed differentially in this way, it is possible to eliminate not only the problem of energy stored in the normal cell N-Cell being repeatedly consumed unnecessarily and the available capacity of the battery module 50 not being fully utilized as a power source, but also various problems such as performance degradation, shortened lifespan, and overcharging that result from this.

[0164] Referring to Figure 14, the first SOC interval (Section 1) is when the SOC of the battery module 50 is the reference SOC (Z R The second SOC interval (section 2) corresponds to the region where the SOC of the battery module 50 is less than the reference SOC (ZR).

[0165] The first SOC interval (Section 1) can be estimated to be a region where the influence of degraded cells (D-Cells) is relatively large. Therefore, the control unit 140 can control the balancing processing unit 130 so that the balancing process for degraded cells (D-Cells) is activated in the time interval DA from time Ta to Tb, which corresponds to the first SOC interval (Section 1).

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

[0167] Figure 4 is a block diagram schematically showing the configuration of the reference processing unit 170 shown in Figure 3, and Figure 10 is a flowchart referenced to explain the process of determining the reference SOC.

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

[0169] The SOC information recording unit 171, in conjunction with the status monitoring unit 120, can record the first SOC, which is the SOC of the battery module 50 at the start of the charging process, and the second SOC, which is the SOC of the battery module 50 at the end of the charging process, by mapping them to the charging process number. As a result, the first SOC time-series data and the second SOC time-series data can be recorded in the SOC information recording unit 171.

[0170] The first SOC time series data includes the first start SOC to the (k-1)th start SOC, which show the SOC of the battery module 50 at the start of each of the first to (k-1)th charging processes performed on the battery module 50 in the past. k is an index that points to the iteration of the most recent charging process and is a natural number greater than or equal to 2. That is, each time the previous charging process for the battery module 50 is completed and a new charging process is performed, k increases by 1.

[0171] The second SOC time series data includes the first end SOC to the (k-1) end SOC, which show the SOC of the battery module 50 at the end of each of the first to (k-1) charging processes.

[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 to 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 to the (k-1)th end SOC from the second SOC time series data, where j is the reference number.

[0174] The reference number (j) can be a predetermined natural number greater than or equal to 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 can 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 can be used to calculate a reference SOC applicable 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 the reference SOC based on the SOC statistics calculated by the statistical processing unit 173.

[0177] The method shown in Figure 10 can be configured to be applied recursively depending on whether the termination condition is satisfied. Depending on the embodiment, the step of checking whether the termination condition is satisfied (S1060) may be omitted.

[0178] The statistical processing unit 173 can update the first SOC time series data, the second SOC time series data, and the SOC statistics used in previous charging processes each time a new charging process is completed.

[0179] For example, if the current charging process is the 31st charging process (i.e., k=31), then 30 first SOCs and 30 second SOCs have already been recorded in the SOC information recording unit 171 from the 1st to the 30th charging processes. The statistical processing unit 173 can 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 this embodiment, the statistical processing unit 173 can selectively use only S (1 or more, less than k) first and second SOCs in reverse order based on the current cycle to calculate the SOC statistic. For example, if k=31 and S=5, the SOC statistic for the current charging process can be calculated based on the five first SOCs and five second SOCs obtained from the 26th to the 30th charging process.

[0181] According to this embodiment, since the SOC statistics are calculated using recent results, the past charge-discharge patterns of the battery module 50 can be effectively reflected by the differential execution of the balancing process.

[0182] For example, the SOC statistic may be the average of S first SOCs and S second SOCs. The reference setting unit 175 may determine a reference SOC that is equal to the SOC statistic or equal to the SOC statistic multiplied 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] Figure 15 is a diagram referenced to illustrate the differential balancing process performed when the baseline SOC is 80%. Figure 15 illustrates that the SOC swing range is 60% to 100%, and the baseline SOC is at 80%, which is the middle of the SOC swing range.

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

[0185] On the other hand, the SOH calculation unit 177 may be configured to calculate the SOH of the battery cell 51 and / or battery module 50 using information such as the electrical characteristics of the battery cell 51 or battery module 50 input from the condition monitoring unit 120, and recorded information such as the durability period or lifespan of the battery cell 51.

[0186] The aforementioned SOH is information representing a kind of degradation level, and the higher the degradation level, the more likely it is that the rate of change in electrical characteristics will accelerate due to an increase in internal resistance, etc.

[0187] Therefore, the reference setting unit 175 can determine the reference SOC based on the SOH of the battery module 50. For example, the reference setting unit 175 can determine a correction coefficient corresponding to the current SOH of the battery module 50 based on a predetermined negative correspondence between SOH and a correction coefficient, and then determine the reference SOC by multiplying the determined correction coefficient by the SOC statistic. According to this, the correction coefficient increases as the SOH of the battery module 50 decreases. As a result, even if the SOC statistic is the same, the reference SOC will increase as the SOH of the battery module 50 decreases.

[0188] As described above, by determining the reference SOC based on the SOH of the battery module 50, it is possible to more precisely divide the interval in which the cell state parameters of the degraded cell D-Cell are higher than those of the normal cell N-Cell, thereby improving the efficiency of the differential balancing process.

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

[0190] The battery management device 100 may be included in the electric vehicle. That is, the electric vehicle according to the present invention may include the battery management device 100 described above or a battery pack containing it. In addition to the battery management device 100 and the battery pack, the electric vehicle according to the present invention may further include a variety of other components such as a vehicle body, a motor, and an ECU (Electronic Control Unit).

[0191] Figure 16 is a diagram that is referenced to schematically illustrate an example of the balancing processing unit shown in Figures 1 and 3. For the sake of understanding, Figure 16 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 Figure 16, the balancing processing unit 130 may include a plurality of buck balancing circuits (D#1 to D#N).

[0193] The control unit 140 is operably coupled to multiple back balancing circuits (D#1 to D#N) so that it can output control signals to each of the multiple back balancing circuits (D#1 to D#N).

[0194] The control signals output from the control unit 140 to each of the multiple back balancing circuits (D#1 to D#N) may be PWM (Pulse Width Modulation) signals in which high-level voltages and low-level voltages alternate.

[0195] Multiple back-balancing circuits (D#1 to D#N) are provided one-to-one with multiple battery cells (#1 to #N). That is, if i is a natural number less than or equal to N, back-balancing circuit D#i is provided for the selective execution of the 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 battery cell #i.

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

[0198] While the balancing switch SW is turned on, a closed circuit is formed including the back balancing circuit D#i and the battery cell #i, 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 dormant period when both charging and discharging of the battery module 50 are stopped (for example, time points t1-t2 in Figure 14), the energy stored in the battery cell #i is consumed by the back balancing circuit D#i, and the cell state parameters of the battery cell #i gradually decrease.

[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 t1 in Figure 14), the charging current of the battery module 50 will be distributed between the battery cell #i and the back balancing circuit D#i. Consequently, the charging speed of the battery cell #i will slow 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 Tb in Figure 14), the battery cell #i can be discharged not only by the discharge current of the battery module 50 but also additionally by the back balancing circuit D#i. Therefore, the discharge rate of the battery cell #i increases.

[0202] <Balancing process for degraded cells only, among normal and degraded cells> Let's 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 the period corresponding to a SOC range of ) or more (for example, from time point Ta to time point Tb in Figure 14), the balancing switch SW of the back balancing circuit D#1 supplied to battery cell #1 remains in the turned-on state, while the balancing switch SW of the back balancing circuit D#2 supplied to battery cell #2 remains in the turned-off state. In other words, the balancing process is performed differently for battery cell #1 and battery cell #2.

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

[0204] During the idle period (for example, time points t1 to t2 in Figure 14), only battery cell #1 discharges from battery cell #2.

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

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

[0207] <Balancing process for normal cells only, among normal and degraded cells> Let's 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 the period corresponding to the following SOC range (for example, from time Tb to time Tc in Figure 14), the balancing switch SW of the back balancing circuit D#1 supplied to battery cell #1 remains in the turned-off state, while the balancing switch SW of the back balancing circuit D#2 supplied to battery cell #2 remains in the turned-on state. In other words, the balancing process is performed differently for battery cell #1 and battery cell #2.

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

[0209] During the idle period (for example, time points t3 to t4 in Figure 14), only battery cell #2 discharges from battery cell #1.

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

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

[0212] Figure 17 is a diagram referenced to schematically illustrate other examples of the balancing unit shown in Figures 1 and 3. For the sake of understanding, Figure 17 shows the configuration of the balancing unit 130, along with the coupling relationship between the battery module 50 and the balancing unit 130.

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

[0214] The control unit 140 is operably coupled to the multiple boost balancing circuits (U#1 to U#N) so that it can output control signals to each of the multiple boost balancing circuits (U#1 to U#N).

[0215] Multiple boost balancing circuits (U#1 to U#N) are provided one-to-one with multiple battery cells (#1 to #N). That is, if i is a natural number less than or equal to N, boost balancing circuit U#i is provided for the selective execution of the balancing process for battery cell #i.

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

[0217] The boost balancing circuit U#i supplies charging power to battery cell #i while operating in response to a control signal from the control unit 140.

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

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

[0220] If the boost balancing circuit U#i operates during the charging period of the battery module 50 (for example, from time t4 to Tc in Figure 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 degraded cells only, among normal and degraded cells> Let's 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 the period corresponding to the following SOC range (for example, from time Tb to time Tc in Figure 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 is deactivated.

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

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

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

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

[0226] <Balancing process for normal cells only, among normal and degraded cells> Let's 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 the period corresponding to a SOC range greater than or equal to (for example, from time Ta to time Tb in Figure 14), 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 (for example, from time point Ta to t1 in Figure 14), the charging speed of battery cell #2 is accelerated by the boost balancing circuit U#2.

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

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

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

[0231] On the other hand, the balancing processing unit 130 may include both the back balancing circuit (D#1~D#N) shown in Figure 16 and the boost balancing circuit (U#1~U#N) shown in Figure 17.

[0232] Let's assume that battery cell #1 is a degraded cell (D-Cell) and battery cell #2 is a normal cell (N-Cell).

[0233] Then, the reference SOC(Z RDuring the period from time Ta to time Tb corresponding to a SOC range of ) or higher, at least temporarily, the balancing switch SW of the back balancing circuit D#1 provided to battery cell #1 may be controlled to the turned-on state, and the boost balancing circuit U#2 provided to battery cell #2 may be controlled to the operating state.

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

[0235] A balancing process using back balancing circuits (D#1 to D#N) may be referred to as a back balancing process, a passive balancing process, or a first balancing process.

[0236] A balancing process using 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 embodiments of the present invention described above are not limited to apparatus and methods, but can also be embodied through a program that implements the functions corresponding to the configuration of the embodiments of the present invention, or through a recording medium on which such a program is recorded. Such embodiments will be easily realized by those skilled in the art from the description of the embodiments described above.

[0238] As described above, the present invention has been explained with limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains.

[0239] Furthermore, the present invention described above can be substituted, modified, and altered in various ways by a person with ordinary skill in the art to which the present invention belongs, without departing from the technical spirit of the invention, and is not limited by the embodiments described above and the accompanying drawings. For diverse modifications, all or part of each embodiment may be selectively combined to form the present invention.

Claims

1. A battery management device for a battery module including multiple battery cells, A state monitoring unit is configured to acquire a plurality of cell state parameters that indicate the electrical state of each of the plurality of battery cells, A balancing processing unit is configured to perform a balancing process, which is a procedure for selectively discharging or charging each of the plurality of battery cells, in order to suppress the variation in the electrical state between the plurality of battery cells. A cell classification unit that classifies each of the plurality of battery cells as either a degraded cell or a normal cell based on the plurality of cell state parameters, The system includes a control unit configured to control the balancing processing unit so that a balancing process is performed differently for at least one of the plurality of battery cells based on the cell state parameters of the degraded cell and the cell state parameters of the normal cell, The cell classification unit is, Based on the aforementioned plurality of cell state parameters, a plurality of cell behavior parameters indicating the behavioral characteristics of the electrical state of each of the plurality of battery cells are calculated, and each of the plurality of battery cells is classified as either a degraded cell or a normal cell based on the relative differences between the plurality of cell behavior parameters. The aforementioned plurality of cell behavior parameters include the rate of change of the plurality of cell state parameters, in a battery management device.

2. The control unit, The balancing processing unit is configured to control the balancing process for the degraded cell if the cell state parameter of the degraded cell is greater than the cell state parameter of the normal cell. The battery management device according to claim 1, wherein the cell state parameter indicates at least one of voltage and SOC.

3. The cell classification unit is The battery management device according to claim 1, wherein each battery cell is mapped to n (where n is a natural number of 1 or more) cell behavior parameters that are ranked in order of magnitude from among the plurality of cell behavior parameters, and each battery cell is classified as a degraded cell.

4. The cell classification unit is The battery management device according to claim 1, configured to select each battery cell as the degraded cell if it satisfies both of the following conditions: the cell behavior parameter during the charging process of the battery module is equal to or greater than a first reference value, and the cell behavior parameter during the discharging process of the battery module is equal to or greater than a second reference value.

5. The aforementioned status monitoring unit, The system is configured to acquire the State of Control (SOC) of the battery module as a module state parameter indicating the electrical state of the battery module. The control unit, The battery management device according to claim 1, configured to control the balancing processing unit so that the balancing process for the degraded cells is executed on the condition that the module state parameter is equal to or greater than a reference SOC while the battery module is being charged.

6. A battery management device for a battery module including a plurality of battery cells, A state monitoring unit is configured to acquire a plurality of cell state parameters indicating the electrical state of each of the plurality of battery cells, and to acquire the State of Control (SOC) of the battery module as a module state parameter indicating the electrical state of the battery module. A balancing processing unit is configured to perform a balancing process, which is a procedure for selectively discharging or charging each of the plurality of battery cells, in order to suppress the variation in the electrical state between the plurality of battery cells. A cell classification unit that classifies each of the plurality of battery cells as either a degraded cell or a normal cell based on the plurality of cell state parameters, 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 the second SOC time series data, A reference setting unit configured to set a reference SOC in the same way as the aforementioned SOC statistical values, The system includes a control unit configured to control the balancing processing unit so that a balancing process is performed differentially on at least one of the plurality of battery cells based on the cell state parameters of the degraded cell and the cell state parameters of the normal cell, and the balancing process is performed on the degraded cell on the condition that the module state parameter is equal to or greater than the reference SOC during charging of the battery module, The first SOC time series data includes a first start SOC to the (k-1) start SOC, which show the SOC of the battery module at the start of each of the first to (k-1) charging processes performed on the battery module in the past. The second SOC time-series data includes the first termination SOC to the (k-1) termination SOC, which show the SOC of the battery module at the end of each of the first to (k-1) charging processes. A battery management device where k is a natural number greater than or equal to 2.

7. The aforementioned statistical processing unit, The battery management device according to claim 6, further configured to calculate the SOC statistics based on the SOH of the battery module.

8. The aforementioned statistical processing unit, Based on the State of Health (SOH) of the aforementioned battery module, a reference number is determined. From the first SOC time series data, extract the (k-j)th starting SOC to the (k-1)th starting SOC. From the second SOC time series data mentioned above, extract the (k-j)th end SOC to the (k-1)th end SOC. The system is configured to calculate the SOC statistic by equaling the average value of the (k-j) starting SOC to the (k-1) starting SOC and the (k-j) ending SOC to the (k-1) ending SOC. The battery management device according to claim 7, wherein j is the reference number.

9. A battery pack comprising a battery management device according to any one of claims 1 to 8.

10. An electric vehicle comprising the battery pack described in claim 9.

11. A battery management method that can be performed by a battery management device according to any one of claims 1 to 8, The state monitoring unit acquires the plurality of cell state parameters that indicate the electrical state of each of the plurality of battery cells, A battery management method comprising the step of the control unit controlling the balancing processing unit so that the balancing process is performed for at least one of the plurality of battery cells based on the plurality of cell state parameters in order to suppress the variation in the electrical state between the battery cells.

12. The step of controlling the balancing processing unit is: A step of classifying each of the plurality of battery cells as either a degraded cell or a normal cell based on the plurality of cell state parameters, The battery management method according to claim 11, further comprising the step of 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.

13. The step of controlling the balancing processing unit is: The steps include: acquiring the State of Control (SOC) of the battery module as a module state parameter indicating the electrical state of the battery module; The battery management method according to claim 12, further comprising the 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.

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