Battery management device and battery management method

Abstract

A battery management device disclosed in the present document comprises: a communication unit for receiving battery data from multiple battery cells; and a control unit for fitting a discharge capacity graph obtained on the basis of the battery data to a sine function, determining a regression coefficient of maximizing a determination coefficient, on the basis of a data fitting function, and determining a maximum curvature point at which a curvature of the discharge capacity graph is maximized, on the basis of the regression coefficient.

Description

Battery management device and battery management method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0182220, filed December 14, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The embodiments disclosed in this document relate to a battery management device and a battery management method for diagnosing a battery condition.

[0005] Recently, active research and development is being conducted on secondary batteries. Here, the term "secondary battery" refers to a rechargeable battery, encompassing both conventional Ni / Cd and Ni / MH batteries, as well as recent lithium-ion batteries. Among secondary batteries, lithium-ion batteries have the advantage of a much higher energy density than conventional Ni / Cd and Ni / MH batteries. Furthermore, lithium-ion batteries can be manufactured in a compact and lightweight form, making them suitable for use as power sources for mobile devices. Furthermore, lithium-ion batteries are attracting attention as a next-generation energy storage medium, as their use is expanding to include power sources for electric vehicles.

[0006] The capacity of these batteries can rapidly decline at certain points due to various factors, including variations in battery cell production / factory conditions and internal degradation mechanisms. Rapid decline in battery capacity can hinder stable and continuous battery use, making early detection essential. However, the lack of a universal and objective method for detecting rapid battery capacity decline has hindered consistent and efficient detection.

[0007] According to one embodiment disclosed in this document, a battery management device and a battery management method are provided that can detect battery defects early in the battery production stage by presenting quantitative criteria for detecting a rapid decrease in battery capacity.

[0008] The technical problems of the embodiments disclosed in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the descriptions below.

[0009] A battery management device according to one embodiment includes a communication unit that receives battery data from a plurality of battery cells, a control unit that fits a discharge capacity graph obtained based on the battery data to a data fitting function, determines a regression coefficient that maximizes a coefficient of determination based on the data fitting function, and determines a maximum curvature point at which the curvature of the discharge capacity graph is maximum based on the regression coefficient.

[0010] The control unit may determine that the plurality of battery cells are defective based on the curvature at the maximum curvature point being greater than a preset reference curvature.

[0011] The above control unit can transmit information about a plurality of battery cells determined to be defective to an external device through a communication unit.

[0012] The control unit can fit the discharge capacity graph obtained based on the battery data with a data fitting function having multiple sine terms.

[0013] The above control unit can determine the maximum curvature point at which the curvature is maximum based on the minimum search point and the maximum search point.

[0014] The above control unit can determine the maximum curvature point at which the curvature is maximum in a range from after the minimum search point to before the maximum search point.

[0015] The minimum search point may include a point at which the discharge capacity begins to decrease, and the maximum search point may include a maximum battery cycle that serves as a reference for the battery test.

[0016] A battery management method according to one embodiment includes receiving battery data from a plurality of battery cells, fitting a discharge capacity graph obtained based on the battery data to a data fitting function, determining a regression coefficient that maximizes a coefficient of determination based on the data fitting function, and determining a maximum curvature point at which the curvature of the discharge capacity graph is maximum based on the regression coefficient.

[0017] A battery management method according to one embodiment may further include determining the plurality of battery cells as defective based on a curvature at the maximum curvature point being greater than a preset reference curvature.

[0018] A battery management method according to one embodiment may further include transmitting information about a plurality of battery cells determined to be defective to an external device through a communication unit.

[0019] Fitting the above discharge capacity graph to a data fitting function may include fitting the above discharge capacity graph obtained based on the battery data to a data fitting function having multiple sine terms.

[0020] Determining the point of maximum curvature may include determining the point of maximum curvature at which the curvature is maximum based on the minimum search point and the maximum search point.

[0021] Determining the point of maximum curvature may include determining the point of maximum curvature at which the curvature is maximum in a range from after the minimum search point to before the maximum search point.

[0022] The minimum search point may include a point at which the discharge capacity begins to decrease, and the maximum search point may include a maximum battery cycle that serves as a reference for the battery test.

[0023] According to a battery management device according to one embodiment, a strategic standard and detection method for a point of rapid decrease in battery capacity can be provided, and during a battery sampling quality inspection process, even if the battery satisfies a discharge capacity standard value at a specific cycle point, a battery cell that additionally has a possibility of rapid decrease in battery capacity can be selected.

[0024] FIG. 1 illustrates a block diagram of a typical battery system including a battery management device according to one embodiment.

[0025] FIG. 2 illustrates a block diagram showing the configuration of a battery management device according to one embodiment.

[0026] FIG. 3 schematically illustrates a flow for determining whether a battery is defective based on curvature by a battery management device according to one embodiment.

[0027] FIG. 4 illustrates a contact source utilized in a battery management device according to one embodiment.

[0028] FIG. 5 illustrates a radius of curvature utilized in a battery management device according to one embodiment.

[0029] FIG. 6 illustrates a case in which a maximum curvature point is detected at the end point of a search range in a battery management device according to one embodiment.

[0030] FIG. 7 illustrates a case in which a maximum curvature point is detected at the start point of a search range in a battery management device according to one embodiment.

[0031] FIG. 8 illustrates a case in which a maximum curvature point is detected at the midpoint of a search range in a battery management device according to one embodiment.

[0032] FIG. 9 illustrates a case in which a maximum curvature point is detected after the midpoint of the search range in a battery management device according to one embodiment.

[0033] FIG. 10 illustrates a control flowchart of a battery management method according to one embodiment.

[0034] Hereinafter, various embodiments disclosed in this document will be described in detail with reference to the attached drawings. In this document, identical components in the drawings are designated by the same reference numerals, and redundant descriptions of identical components are omitted.

[0035] With respect to the various embodiments disclosed in this document, specific structural and functional descriptions are merely illustrative for the purpose of explaining the embodiments, and the various embodiments disclosed in this document may be implemented in various forms and should not be construed as being limited to the embodiments described in this document.

[0036] The expressions "first," "second," "first," or "second" used in various embodiments may describe various components, regardless of order and / or importance, and do not limit the components. For example, without departing from the scope of the embodiments disclosed herein, a first component may be renamed a second component, and similarly, a second component may also be renamed a first component.

[0037] The terms used in this document are intended solely to describe specific embodiments and may not be intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise.

[0038] All terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art of the embodiments disclosed herein. Terms defined in commonly used dictionaries may be interpreted as having the same or similar meaning in the context of the relevant technology, and unless explicitly defined herein, they shall not be interpreted in an idealized or overly formal sense. In some cases, even if a term is defined herein, it cannot be interpreted to exclude the embodiments disclosed herein.

[0039] FIG. 1 illustrates a block diagram showing the configuration of a typical battery system including a battery management device according to various embodiments.

[0040] Specifically, FIG. 1 schematically illustrates a battery system (10) and an upper controller (20) included in an upper system according to one embodiment disclosed in this document.

[0041] As illustrated in FIG. 1, the battery system (10) may include a plurality of battery modules (12), a sensor unit (14), a switching unit (16), and a battery management device (1). At this time, the battery system (10) may be equipped with a plurality of battery modules (12), sensor units (14), switching units (16), and battery management devices (1).

[0042] A plurality of battery modules (12) may include at least one rechargeable battery cell (13). The battery cell (13) may include a cathode, a cathode material, a cathode material, a separator, an electrolyte, a polymer, and a case. In this case, the plurality of battery modules (12) may be connected in series or in parallel.

[0043] The sensor unit (14) may include a current sensor (2), a voltage sensor (3), and a temperature sensor (not shown).

[0044] The current sensor (2) can detect the current used in the process of determining the discharge capacity graph of the battery cell (13).

[0045] The current sensor (2) may include any configuration that generates a signal corresponding to the size of the charging current, and the current sensor (2) may be installed on a charging / discharging path, which is a path through which the charging / discharging current flows in the battery.

[0046] The current sensor (2) can measure the battery current flowing in the battery, i.e., the charging current and the discharging current, and transmit the measurement results to the battery management device (1). According to one embodiment, the current sensor (2) can measure the battery current at predetermined intervals during a charging cycle in which the battery is charged with power from an external device or a discharging cycle in which the battery is discharged, and transmit the measurement results to the battery management device (1).

[0047] The voltage sensor (3) can be configured to be connected in parallel to the battery, detect the battery voltage, which is the voltage across both terminals of the battery, and generate a voltage signal representing the detected battery voltage.

[0048] A temperature sensor (not shown) may be configured to measure the battery temperature and generate a temperature signal representing the measured battery temperature. The temperature sensor may be positioned within the case so as to measure a temperature close to the actual temperature of the battery. For example, the temperature sensor may be attached to the surface of at least one battery cell included in the cell group and may detect the surface temperature of the battery cell as the battery temperature.

[0049] The temperature sensor may be configured to measure the external temperature, which is the temperature at a predetermined location away from the battery, and generate a temperature signal representing the measured external temperature. The temperature sensor may be positioned at a predetermined location outside the case where heat exchange between the battery and the atmosphere occurs. According to an embodiment, the temperature sensor may be implemented using one or a combination of two or more known temperature detection elements, such as a thermocouple, a thermistor, or a bimetal.

[0050] In Fig. 1, the sensor unit (14) is connected between the positive electrode of the battery cell (13) and the switching unit (16), but the configurations and connection relationships between the configurations shown in Fig. 1 are only examples and are not limited thereto.

[0051] The switching unit (16) is connected in series to the (+) terminal side or the (-) terminal side of the battery module (12) to control the charge / discharge current flow of the battery module (12). For example, the switching unit (16) may use at least one relay, magnetic contactor, etc. depending on the specifications of the battery system (10).

[0052] The battery management device (1) can monitor the voltage, current, temperature, etc. of the battery system (10) and control and manage it to prevent overcharging and overdischarging, etc., and may include, for example, a BMS (Battery Management System).

[0053] The battery management device (1) is an interface for receiving values ​​measured from various parameters, and may include a plurality of terminals and a circuit connected to these terminals to process the values ​​received. In addition, the battery management device (1) may control the ON / OFF of a switching unit (16), for example, a relay or a contactor, and may be connected to a battery module (12) to monitor the status of each battery module (12).

[0054] In addition, the battery management device (1) can receive temperature data, voltage data, and current data from the sensor unit (14) to obtain battery status information and diagnose the status of the battery.

[0055] The upper controller (20) can transmit a control signal for controlling the battery module (12) to the battery management device (1). Accordingly, the battery management device (1) can be controlled for operation based on the control signal received from the upper controller (20). In addition, the battery module (12) may be a component included in an ESS (Energy Storage System). In this case, the upper controller (20) may be a controller (BBMS) of a battery bank including a plurality of battery systems (10) or an ESS controller that controls the entire ESS including a plurality of banks. However, the battery system (10) is not limited to this purpose.

[0056] FIG. 2 illustrates a block diagram showing the configuration of a battery management device according to one embodiment.

[0057] Referring to FIG. 2, a battery management device (1) according to one embodiment includes a control unit (100) including at least one processor (110) and a memory (120) and a communication unit (200), and can diagnose a battery by communicating with an external device (4) through the communication unit (200).

[0058] According to an embodiment, an external device (4) communicating with a battery management device (1) may include a user terminal and a server device that transmit results diagnosed by the battery management device (1).

[0059] Specifically, when the external device (4) is a user terminal, the control unit (100) of the battery management device (1) can transmit the battery diagnosis results to the user terminal so that the user can check them. At this time, the user terminal may include, but is not limited to, a personal computer, a terminal, a portable telephone, a smart phone, a handheld device, a wearable device, etc.

[0060] In addition, when the external device (4) is a server device, the server device may be implemented as various computing devices such as a workstation, a cloud, a data drive, a data station, etc. The server device may be implemented as one or more server devices that are physically or logically separated based on function, detailed configuration of function, or data, etc., and may transmit and receive data and process the transmitted and received data through communication between each server device.

[0061] A battery management device (1) according to one embodiment may refer to any electronic device including a processor (110) and a memory (120), and may be mounted on a vehicle and operated. Each component of the battery management device (1) will be described in detail below.

[0062] The communication unit (200) may include a wireless communication unit (210) and a wired communication unit (220) to communicate with an external device (4). The communication unit (200) may transmit and receive programs for calculating characteristic values ​​of battery cells, class classification, and lifespan estimation, as well as various data, from a separately provided external server.

[0063] The wireless communication unit (210) may include at least one of a short-range communication module and a long-range communication module.

[0064] The short-range communication module can communicate with an external device (4) adjacent to the battery management device (1) using a short-range communication method. Here, the short-range communication module can utilize one of the following communication methods: Bluetooth, Bluetooth low energy, infrared data association (IrDA), Zigbee, Wi-Fi, Wi-Fi direct, Ultra Wideband (UWB), or near field communication (NFC).

[0065] The remote communication module may include a communication module that performs various types of remote communication and may include a mobile communication unit. The mobile communication unit may transmit and receive a wireless signal with at least one of a base station, an external terminal, and an external device (4) on a mobile communication network. In addition, the remote communication module may communicate with an external device (4) or an external device (4) such as another electronic device through a surrounding access point (AP). The access point (AP) may connect a local area network (LAN) to which the battery management device (1) is connected to a wide area network (WAN) to which a communication server is connected. Accordingly, the battery management device (1) may be connected to the communication server through the wide area network (WAN) with the external device (4) and communicate with each other.

[0066] The wired communication unit (220) can connect to a wired communication network and communicate with an external device (4) through the wired communication network. For example, the wired communication unit (220) can connect to a wired communication network through Ethernet (IEEE 802.3 technology standard) or connect to a wired communication network through CAN communication, and transmit and receive data with the external devices (4) through the wired communication network.

[0067] A battery management device (1) according to one embodiment may include an input / output interface (not shown). An interface may be provided that connects an input device (not shown) such as a keyboard, mouse, or touch panel, an output device (not shown) such as a display, and a processor (110) to transmit and receive data.

[0068] The memory (120) can store various information necessary for operating the battery management device (1). Specifically, the memory (120) can store an operating system and a program necessary for operating the battery management device (1), or store data necessary for operating the battery management device (1).

[0069] Specifically, the memory (120) can store various programs related to calculating characteristic values ​​of battery cells, classifying classes, and estimating lifespan. In addition, the memory (120) can store various data such as voltage, current, and characteristic value data of each battery cell.

[0070] Additionally, the memory (120) can store the regression coefficient and reference curvature of the battery cell (13) estimated by the processor (110).

[0071] The memory (120) may include volatile memory (120) such as Static Random Access Memory (S-RAM) and Dynamic Random Access Memory (D-RAM) for temporarily storing data. In addition, the memory (120) may include nonvolatile memory (120) such as Read Only Memory (ROM), Erasable Programmable Read Only Memory (EPROM), and Electrically Erasable Programmable Read Only Memory (EEPROM) for long-term storage of data.

[0072] The processor (110) outputs control signals to control the battery management device (1) as a whole. The processor (110) may include one or more central processing units (CPUs) and graphics processing units (GPUs). In this case, the processor (110) may be implemented as an array of a plurality of logic gates, or may be implemented as a combination of a general-purpose microprocessor (110) and a memory (120) storing a program that can be executed on the microprocessor (110).

[0073] The aforementioned memory (120) and processor (110) may be included in the control unit (100), and the control unit (100) may control the aforementioned components to determine whether a defect has occurred in the battery cell.

[0074] Specifically, the control unit (100) can fit a discharge capacity graph obtained based on the battery data to a data fitting function, and determine a regression coefficient that maximizes a coefficient of determination based on the data fitting function. That is, the control unit (100) can fit a discharge capacity graph to a sine function to remove noise from the data and obtain a constant curvature shape.

[0075] The control unit (100) can determine the maximum curvature point where the curvature of the discharge capacity graph is maximum based on the regression coefficient, and the control unit (100) can compare the maximum curvature point with a preset reference curvature to determine whether the battery cell is defective.

[0076] Specifically, the control unit (100) can determine a battery cell whose curvature at the maximum curvature point is greater than a preset reference curvature as a defective battery cell, and the control unit (100) can transmit information about a plurality of battery cells determined to be defective to an external device (4) through the communication unit (200) to inform a battery user or inspector of whether the battery cell is defective.

[0077] In addition, the control unit (100) can fit a discharge capacity graph obtained based on battery data to a sine function having multiple sine terms, and the control unit (100) can determine a maximum curvature point where the curvature is maximum based on the search point and the maximum search point. Specifically, the control unit (100) can limit the range of cycles for determining the maximum curvature point to a specific minimum / maximum cycle range.

[0078] That is, the control unit (100) can determine the maximum curvature point where the curvature is maximum in the range from after the minimum search point to before the maximum search point.

[0079] In this way, the battery management device (1) according to one embodiment can detect a defective battery cell based on curvature at an early point in time when it is not possible to determine whether it is defective using other defect detection algorithms.

[0080] FIG. 3 schematically illustrates a flow chart of a battery management device according to one embodiment, which determines whether a battery is defective based on curvature. Components 101 to 104 in FIG. 3 are implemented in the form of software blocks, stored in memory (120), and executed by a processor (110).

[0081] Referring to FIG. 3, the control unit (100) can receive current values ​​and voltage values ​​from the current sensor (2) and the voltage sensor (3).

[0082] Thereafter, the discharge capacity graph generation unit (101) of the control unit (100) can generate a discharge capacity graph based on the current value and the voltage value, and the discharge capacity graph can mean a graph that shows the total amount of energy provided by the battery according to time or cycle when using the charged power. In addition, the control unit (100) can also generate an SOH (State Of Health) graph instead of the discharge capacity graph, but the following will describe an embodiment using the discharge capacity graph.

[0083] The sine function fitting unit (102) of the control unit (100) can fit the discharge capacity graph generated based on battery data with a sine function having multiple terms. At this time, there is no limit to the number of sine function terms, but in order to prevent overfitting and distortion at both ends, a sine function having two terms is used as the most suitable fitting function for the discharge capacity graph. The formula can be applied.

[0084] Thereafter, the regression coefficient determination unit (103) of the control unit (100) can determine the regression coefficient that maximizes the coefficient of determination (R-squared) based on the sine function, that is, the control unit (100) can determine the regression coefficient that maximizes the coefficient of determination in order to find a regression model that can optimally explain the relationship between the dependent variable and the independent variable. The regression coefficient can be determined experimentally, and in the discharge capacity graph, the sine sum function having multiple terms can be utilized as a fitting function because the sine sum function having multiple terms has a higher coefficient of determination than a single sine function or an exponential function.

[0085] The defectiveness judgment unit (104) of the control unit (100) can determine the plurality of battery cells as defective based on whether the curvature at the maximum curvature point determined in the discharge capacity graph fitted by the sine function is greater than a preset reference curvature.

[0086] Thereafter, the control unit (100) can transmit information about the battery cell determined to be defective to an external device (4) through the communication unit (200), and the battery user or manager can detect the defect of the battery at an early stage.

[0087] Previously, methods for detecting sudden decline in battery capacity included methods using raw data, methods using moving averages, and methods using the intersection of tangent lines. However, existing methods were unable to consistently find the point of maximum curvature. On the other hand, according to one embodiment of the present invention, a battery management device (1) determines the point of maximum curvature based on a discharge capacity graph fitted to a sine function, thereby providing a consistent and noise-insensitive battery capacity decline detection algorithm.

[0088] FIG. 4 illustrates a contact circle utilized in a battery management device according to one embodiment, and FIG. 5 illustrates a radius of curvature utilized in a battery management device according to one embodiment.

[0089] Referring to Figure 4, curvature refers to the degree to which a curve is bent, and the curvature can be calculated as the reciprocal of the radius of curvature (r) of the osculating circle.

[0090] Specifically, as shown in Fig. 4, for a circle passing through three points P, P1, and P2 on the curve y=f(x), the limit of the circle that occurs when P1 and P2 become infinitely close to P is the contact circle, and the radius of the contact circle means the radius of curvature (r).

[0091] Referring to FIG. 5, since the angle formed by the tangent vector and the normal vector perpendicular to each vector at two points P and Q is θ, if the arc PQ is equal to the curve PQ, the central angle of the sector is also θ. At this time, if the length of the arc PQ is s, then s = rθ, so the radius of curvature (r) can be determined by the mathematical formula below.

[0092]

[0093] The control unit (100) can obtain mathematical expression 2 by modifying mathematical expression 1, and obtain mathematical expressions 3 and 4 by differentiating the curve length in mathematical expression 2.

[0094]

[0095]

[0096]

[0097] The control unit (100) uses mathematical expressions 3 and 4. If we organize it, we can generate mathematical equation 5.

[0098]

[0099] The control unit (100) can calculate the curvature as in mathematical expression 6 based on the relationship that the curvature (k) is the reciprocal of the radius of curvature (r).

[0100]

[0101] In this way, the control unit (100) can calculate the curvature of the graph to determine the point where the curvature of the discharge capacity graph is maximum as the point where the capacity of the battery rapidly decreases.

[0102] FIG. 6 illustrates a case in which a maximum curvature point is detected at an end point of a search range in a battery management device according to one embodiment, and FIG. 7 illustrates a case in which a maximum curvature point is detected at a start point of a search range in a battery management device according to one embodiment.

[0103] Referring to FIG. 6, the control unit (100) can obtain a discharge capacity graph (b) by fitting the raw data (a) to a sine function. At this time, the control unit (100) can detect the maximum curvature of the discharge capacity graph (b), and specifically, the control unit (100) can determine the maximum curvature point where the curvature is maximum in the search range (d) from after the minimum search point to before the maximum search point.

[0104] That is, the control unit (100) can determine the minimum search point as 50 cycles and the maximum search point as 300 cycles, as shown in FIG. 6.

[0105] Specifically, during the battery cell quality testing process, the activation process through repeated charge and discharge cycles may temporarily increase battery capacity in the early cycles. Therefore, the minimum search point may include the point at which the discharge capacity begins to decrease. Specifically, during the first few dozen cycles of battery process testing, there may be a period in which capacity increases due to internal chemical reactions during the activation process during the battery charge and discharge process. Accordingly, the minimum search point may include the point at which capacity increases in the early cycle and then begins to decrease.

[0106] In addition, since the battery cell quality test is determined to have passed only when the discharge capacity in a specific cycle is measured to be n% or more compared to the initial state during the battery cell quality test, the maximum search point may include the maximum battery cycle that serves as the standard for the battery test.

[0107] In FIG. 6, the maximum curvature point (c) detected by the control unit (100) may be located at the end point of the search range (d), and the control unit (100) may determine that the battery is normal because the maximum curvature point (c) is not detected within the search range (d).

[0108] Additionally, referring to the lower graph of Fig. 6, the maximum value of the actual curvature is at the cycle 0 point, but the maximum value of the curvature determined by the control unit (100) is the maximum value of the curvature within the search range (d), which can be determined as the cycle 300 point.

[0109] Next, referring to FIG. 7, the control unit (100) can obtain a discharge capacity graph (b) by fitting the raw data (a) to a sine function, similarly to FIG. 6. In addition, the control unit (100) can determine the maximum curvature point where the curvature is maximum in the search range (d) from after the minimum search point to before the maximum search point.

[0110] That is, the control unit (100) can determine the minimum search point as 50 cycles and the maximum search point as 300 cycles. However, the minimum and maximum search points here can be set differently depending on the type and purpose of the battery cell.

[0111] In FIG. 7, the maximum curvature point (c) detected by the control unit (100) may be located at the starting point of the search range (d), and the control unit (100) may determine that the battery is normal because the maximum curvature point (c) is not detected within the search range (d).

[0112] Additionally, referring to the lower graph of Fig. 7, the maximum value of the actual curvature is at the cycle 0 point, but the maximum value of the curvature determined by the control unit (100) is the maximum value of the curvature within the search range (d), which can be determined as the cycle 50 point.

[0113] FIG. 8 illustrates a case in which a maximum curvature point is detected at a midpoint of a search range in a battery management device according to one embodiment, and FIG. 9 illustrates a case in which a maximum curvature point is detected after a midpoint of a search range in a battery management device according to one embodiment.

[0114] Referring to FIG. 8, the control unit (100) can obtain a discharge capacity graph (b) by fitting raw data (a) to a sine function. In addition, the control unit (100) can determine a maximum curvature point where the curvature is maximum within a search range (e) from after the minimum search point to before the maximum search point.

[0115] That is, the control unit (100) can determine the minimum search point as 50 cycles and the maximum search point as 300 cycles.

[0116] In FIG. 8, the maximum curvature point (c) detected by the control unit (100) may be located at the 150 cycle point, which is the midpoint of the search range (e), and the control unit (100) may determine that the battery is defective because the maximum curvature point (c) is detected within the search range (e).

[0117] Additionally, referring to the lower graph of Fig. 8, the maximum values ​​of the actual curvature are at two points, namely, the cycle 0 point and the cycle 150 point, but the maximum value of the curvature determined by the control unit (100) is the maximum value of the curvature within the search range (e), which can be determined as the cycle 150 point.

[0118] At this time, in the quality test process of the battery cell, the test unsatisfactory point (d) where the discharge capacity is less than n% of the initial value is approximately the 180th cycle point, so the control unit (100) can detect the 150th cycle point, which is the maximum curvature point, earlier than the test unsatisfactory point (d).

[0119] Similarly, referring to FIG. 9, the control unit (100) can obtain a discharge capacity graph (b) by fitting the raw data (a) to a sine function. In addition, the control unit (100) can determine the maximum curvature point where the curvature is maximum in the search range (e) from after the minimum search point to before the maximum search point, and the control unit (100) can determine the minimum search point as 50 cycles and the maximum search point as 300 cycles.

[0120] In FIG. 9, the maximum curvature point (c) detected by the control unit (100) may be located at a point 200 cycles to the right of the midpoint of the search range (e), and the control unit (100) may determine that the battery is defective because the maximum curvature point (c) is detected within the search range (e).

[0121] Additionally, referring to the lower graph of Fig. 9, the maximum values ​​of the actual curvature are at two points, namely, the cycle 0 point and the cycle 200 point, but the maximum value of the curvature determined by the control unit (100) is the maximum value of the curvature within the search range (e), which can be determined as the cycle 200 point.

[0122] At this time, in the quality test process of the battery cell, the test unsatisfactory point (d) where the discharge capacity is less than n% of the initial value is approximately the 240th cycle point, so the control unit (100) can detect the 200th cycle point, which is the maximum curvature point, earlier than the test unsatisfactory point (d).

[0123] Accordingly, the control unit (100) can remove noise and actively and quickly detect whether the battery capacity is rapidly decreasing.

[0124] FIG. 10 illustrates a control flowchart of a battery management method according to one embodiment.

[0125] Referring to FIG. 10, the control unit (100) can receive battery data of multiple battery cells from the communication unit (200) (1000). At this time, the battery data can be received from the sensor unit via wired / wireless communication, or from an external server, such as a cloud server, via the communication unit (200).

[0126] Thereafter, the control unit (100) can obtain a discharge capacity graph based on the received battery data (1010). The control unit (100) can also generate an SOH graph instead of the discharge capacity graph, and the same algorithm for deriving the maximum curvature of the graph can be applied.

[0127] The control unit (100) can fit the acquired discharge capacity graph to a sine function (1020) and determine a regression coefficient that maximizes the coefficient of determination for optimization (1030). Thereafter, the control unit (100) can determine the curvature of the discharge capacity graph fitted with the sine graph based on the regression coefficient determined within a preset search range (1040).

[0128] The control unit (100) can determine whether the maximum curvature of the sine graph exceeds a preset reference curvature (1050), and the control unit (100) can determine the battery status as abnormal if the maximum curvature exceeds the preset reference curvature (yes of 1050) (1060), and the control unit (100) can determine the battery status as normal if the maximum curvature does not exceed the preset reference curvature (no of 1050) (1070).

[0129] In this way, the battery management device (1) according to one embodiment can detect a rapid decrease in battery capacity early, so that battery failure can be detected more efficiently and data for analyzing the cause of battery failure can be secured.

[0130] Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform the operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0131] Computer-readable storage media include all types of storage media that store instructions that can be deciphered by a computer. Examples include read-only memory (ROM), random access memory (RAM), magnetic tape, magnetic disks, flash memory, and optical data storage devices.

[0132] Additionally, a computer-readable recording medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory storage medium" simply means a tangible device that does not contain signals (e.g., electromagnetic waves). This term does not distinguish between cases where data is permanently stored in the storage medium and cases where data is temporarily stored. For example, a "non-transitory storage medium" may include a buffer in which data is temporarily stored.

[0133] According to one embodiment, the method according to various embodiments disclosed in the present document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable recording medium (e.g., compact disc read only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., a downloadable app) may be temporarily stored or temporarily generated on a machine-readable recording medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0134] Although all components constituting the embodiments disclosed in this document have been described as being combined or operating in combination as one, the embodiments disclosed in this document are not necessarily limited to such embodiments. That is, within the scope of the purpose of the embodiments disclosed in this document, all of the components may be selectively combined and operated one or more times.

[0135] Furthermore, terms such as "include," "comprise," or "have" described above, unless specifically stated otherwise, imply that the corresponding component may be present, and therefore should be interpreted to include other components rather than excluding other components. All terms, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiments disclosed in this document pertain, unless otherwise defined. Commonly used terms, such as terms defined in dictionaries, should be interpreted to be consistent with the contextual meaning of the relevant technology, and shall not be interpreted in an idealized or overly formal sense, unless explicitly defined in this document.

[0136] The above description is merely an illustrative description of the technical idea disclosed in this document, and those skilled in the art to which the embodiments disclosed in this document pertain may make various modifications and variations without departing from the essential characteristics of the embodiments disclosed in this document. Therefore, the embodiments disclosed in this document are not intended to limit the technical idea of ​​the embodiments disclosed in this document, but to explain it, and the scope of the technical idea disclosed in this document is not limited by these embodiments. The scope of protection of the technical idea disclosed in this document should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of this document.

[0137] [Explanation of symbols]

[0138] 1: Battery management device

[0139] 2: Voltage sensor

[0140] 3: Current sensor

[0141] 4: External devices

[0142] 10: Battery system

[0143] 12: Multiple battery modules

[0144] 13: Battery cell

[0145] 14: Sensor section

[0146] 16: Switching section

[0147] 20: Upper controller

[0148] 100: Control Unit

[0149] 110: Processor

[0150] 120: Memory

[0151] 200: Communications Department

[0152] 210: Wireless Communications Department

[0153] 220: Wired Communications Department

Claims

1. A communication unit for receiving battery data from multiple battery cells; and Fitting the discharge capacity graph obtained based on the above battery data to the data fitting function, Determine the regression coefficient that maximizes the coefficient of determination based on the above data fitting function, A battery management device including a control unit that determines a maximum curvature point at which the curvature of the discharge capacity graph is maximum based on the regression coefficient.

2. In claim 1, The above control unit, A battery management device that determines the plurality of battery cells as defective based on a curvature at the maximum curvature point being greater than a preset reference curvature.

3. In claim 1, The above control unit, A battery management device that determines the plurality of battery cells as defective based on the differential value of the curvature curve at the maximum curvature point becoming 0.

4. In claim 3, The above control unit, A battery management device that transmits information about multiple battery cells determined to be defective to an external device via a communication unit.

5. In claim 1, The above control unit, A battery management device that fits the discharge capacity graph obtained based on the above battery data with a data fitting function having multiple sine terms.

6. In claim 1, The above control unit, A battery management device that determines the maximum curvature point at which the curvature is maximum based on the minimum search point and the maximum search point.

7. In claim 6, The above control unit, A battery management device that determines the maximum curvature point at which the curvature is maximum in a range from after the minimum search point to before the maximum search point.

8. In claim 7, The above minimum search point includes the point where the discharge capacity begins to decrease, The above maximum search point is a battery management device that includes the maximum battery cycle that serves as a reference for the battery test.

9. Receive battery data from multiple battery cells; Fitting the discharge capacity graph obtained based on the above battery data to a data fitting function; Determine the regression coefficient that maximizes the coefficient of determination based on the above data fitting function; A battery management method, comprising: determining a maximum curvature point at which the curvature of the discharge capacity graph is maximum based on the regression coefficient.

10. In claim 9, A battery management method further comprising: determining the plurality of battery cells as defective based on a curvature at the maximum curvature point being greater than a preset reference curvature; 11. In claim 9, A battery management method for determining that the plurality of battery cells are defective based on the differential value of the curvature curve at the maximum curvature point becoming 0.

12. In claim 11, A battery management method further comprising: transmitting information about a plurality of battery cells determined to be defective to an external device through a communication unit; 13. In claim 10, Fitting the above discharge capacity graph to the data fitting function is: A battery management method, comprising: fitting the discharge capacity graph obtained based on the battery data with a data fitting function having multiple sine terms.

14. In claim 10, Determining the point of maximum curvature is: A battery management method, comprising: determining a maximum curvature point at which the curvature is maximum based on a minimum search point and a maximum search point.

15. In claim 14, Determining the point of maximum curvature is: A battery management method, comprising: determining a point of maximum curvature at which the curvature is maximum in a range from after the minimum search point to before the maximum search point.

16. In claim 14, The above minimum search point includes the point where the discharge capacity begins to decrease, The above maximum search point is a battery management method including a maximum battery cycle that serves as a criterion for battery testing.

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