Battery management device, battery pack, and battery management method

Abstract

The battery management device and method according to the embodiments of the present application aims at performing appropriate control to increase the life of the battery cell by determining whether the deterioration of the battery cell has been accelerated. According to the aspect of the present application, both the voltage fluctuation pattern and the differential capacity fluctuation pattern between a plurality of peaks included in a plurality of differential curves are considered, and thus it is possible to accurately determine whether the battery cell is in an accelerated deterioration state.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2020-0115637, filed in Korea on September 9, 2020, the disclosure of which is incorporated herein by reference.

[0002] This disclosure relates to battery management devices and methods, and more specifically, to a battery management device and method for determining whether the degradation of a battery cell is accelerated. Background Technology

[0003] Recently, demand for portable electronic products such as laptops, cameras, and mobile phones has increased dramatically, and electric vehicles, energy storage batteries, robots, and satellites have seen significant development. Therefore, research is actively underway on high-performance batteries that allow for repeated charging and discharging.

[0004] Currently available batteries include nickel-cadmium (NiCd), nickel-metal hydride (NiMH), nickel-zinc (NiZn), and lithium-ion batteries. Among these, lithium-ion batteries have attracted much attention due to their virtually non-existent memory effect compared to nickel-based batteries, as well as their extremely low self-charge rate and high energy density.

[0005] Generally, because these batteries degrade with use, it is necessary to accurately determine their state in order to accurately estimate the state of charge (SOC) and state of health (SOH) of the degraded battery, or to implement controls to increase the lifespan of the degraded battery. Specifically, to effectively increase battery life, control is needed corresponding to the degree of battery degradation (degradation rate).

[0006] Traditionally, to detect battery anomalies, an inspection system has been disclosed that compares feature points of a pre-stored V-dQ / dV curve with feature points of the actual dQ / dV value (Patent Document 1). However, in related technologies, battery anomalies are detected solely by determining whether the feature points of the actual dQ / dV value fall within a predetermined voltage (V) range and a predetermined dQ / dV range.

[0007] In other words, the relevant technologies only determine the abnormality or defect of the battery, but do not disclose any configuration for judging the degree of battery degradation in order to increase battery life.

[0008] (Patent Document 1) KR 10-2013-0142884A Summary of the Invention

[0009] Technical issues

[0010] This disclosure relates to solving problems in the related art, and therefore aims to provide a battery management device and method that can perform appropriate controls to increase the lifespan of the battery cells by determining whether the degradation of the battery cells is accelerated.

[0011] These and other objects and advantages of this disclosure may be understood from the following detailed description and will become more apparent from exemplary embodiments of this disclosure. Furthermore, it will be readily understood that the objects and advantages of this disclosure may be achieved by the means shown in the appended claims and combinations thereof.

[0012] Technical solution

[0013] According to one aspect of the present disclosure, a battery management device may include: a curve generation unit configured to: acquire battery information including the voltage and capacity of a battery cell and generate a battery curve representing the correspondence between the voltage and the capacity based on the acquired battery information; a curve conversion unit configured to: receive the battery curve from the curve generation unit and convert the received battery curve into a differential curve representing the correspondence between the voltage and the differential capacity of the voltage; and a control unit configured to: acquire multiple differential curves of the battery cell converted by the curve conversion unit, select peak values ​​including those in a preset standard voltage region from each of the acquired multiple differential curves, determine voltage variation patterns and differential capacity variation patterns of the selected multiple peak values, and determine whether the degradation of the battery cell is accelerated based on whether the determined voltage variation pattern corresponds to a preset first reference pattern and whether the determined differential capacity variation pattern corresponds to a preset second reference pattern.

[0014] The control unit can be configured to determine the voltage variation mode and the differential capacity variation mode for each pair of corresponding peaks among multiple peaks.

[0015] The first reference mode can be configured to increase the voltage toward a higher voltage to be equal to or greater than a preset standard voltage.

[0016] The control unit can be configured to determine whether the voltage change mode corresponds to the first reference mode by judging whether the determined voltage change mode is an increasing mode and whether the voltage difference between the corresponding peaks is equal to or greater than the standard voltage.

[0017] The second reference mode can be configured as a mode with increased differential capacity.

[0018] The control unit can be configured to determine whether the differential capacity change mode corresponds to the second reference mode by judging whether the determined differential capacity change mode is an increasing mode.

[0019] The control unit can be configured to determine multiple peak voltage variation patterns and differential capacity variation patterns based on the cycle sequence of the battery cells.

[0020] The control unit can be configured to determine at least one target peak among multiple peaks, where the voltage variation pattern corresponds to a first reference pattern and the differential capacity variation pattern corresponds to a second reference pattern.

[0021] The control unit can be configured to determine the degradation of the battery cell and accelerate from the lowest cycle among the cycles corresponding to at least one target peak.

[0022] The control unit can be configured to set the discharge termination voltage of the battery cell to be equal to or greater than the voltage corresponding to at least one target peak value.

[0023] The standard voltage region can be preset to be a portion of the battery cell's voltage region near the end of discharge.

[0024] According to another aspect of this disclosure, a battery pack may include a battery management device according to another aspect of this disclosure.

[0025] According to another aspect of the battery management method disclosed herein, the battery management method may include: a battery information acquisition step, which acquires battery information including the voltage and capacity of a battery cell; a battery curve generation step, which generates a battery curve representing the correspondence between voltage and capacity based on the acquired battery information; a differential curve conversion step, which converts the battery curve into a differential curve representing the correspondence between voltage and differential capacity for that voltage; a peak selection step, which selects a peak value included in a preset standard voltage region from each of a plurality of differential curves converted in the differential curve conversion step; a mode determination step, which determines a voltage variation mode of the voltage of the plurality of selected peak values ​​and a differential capacity variation mode of the differential capacity; and a degradation acceleration determination step, which determines whether the degradation of the battery cell is accelerated based on whether the determined voltage variation mode corresponds to a preset first reference mode and whether the determined differential capacity variation mode corresponds to a preset second reference mode.

[0026] Technical effect

[0027] According to one aspect of this disclosure, since both the voltage change pattern and the differential capacity change pattern between multiple peaks included in multiple differential curves are considered, it has the advantage of being able to accurately determine whether the state of the battery cell is in a state of accelerated degradation.

[0028] The effects of the present invention are not limited to those described above, and those skilled in the art will clearly understand other unmentioned effects from the description of the claims. Attached Figure Description

[0029] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide a further understanding of the technical features of the present disclosure; therefore, the present disclosure should not be construed as limiting the scope of the drawings.

[0030] Figure 1 This is a schematic diagram illustrating a battery management device according to an embodiment of the present disclosure.

[0031] Figure 2 This is a schematic diagram illustrating a first differential curve according to an embodiment of the present disclosure.

[0032] Figure 3 This is a schematic diagram showing the first to seventh differential curves according to embodiments of the present disclosure.

[0033] Figure 4 This is an enlarged view showing a portion of the first to seventh differential curves according to an embodiment of the present disclosure.

[0034] Figure 5 This is an enlarged view showing another portion of the first to seventh differential curves according to an embodiment of the present disclosure.

[0035] Figure 6 This is an enlarged view showing a portion of the first to seventh differential curves according to an embodiment of the present disclosure.

[0036] Figure 7 This is a schematic diagram illustrating the coulombic efficiency of a battery cell in each cycle of accelerated degradation determined by a battery management device according to an embodiment of the present disclosure.

[0037] Figure 8 It is a graph that schematically shows the relationship between the capacity and differential voltage of a battery cell.

[0038] Figure 9 This is a diagram schematically illustrating an exemplary configuration of a battery pack including a battery management device according to an embodiment of the present disclosure.

[0039] Figure 10 This is a schematic diagram illustrating a battery management method according to another embodiment of the present disclosure.

[0040] (See attached image labels)

[0041] 1: Battery pack

[0042] 2: Charging / Discharging Unit

[0043] 100: Battery Management Device

[0044] 110: Curve generation unit

[0045] 120: Curve Transformation Unit

[0046] 130: Control Unit

[0047] 140: Storage unit

[0048] 200: Unit of measurement

[0049] B: Battery unit Detailed Implementation

[0050] It should be understood that the terms used in the specification and appended claims should not be construed as limited to their general and dictionary meanings, but should be interpreted based on their meanings and concepts corresponding to the technical aspects of this disclosure, on the basis of the principle that the inventors are allowed to define the terms appropriately for the best interpretation.

[0051] Therefore, the description presented herein is merely a preferred example for illustrative purposes only and is not intended to limit the scope of this disclosure. It should be understood that other equivalent substitutions and modifications may be made thereto without departing from the scope of this disclosure.

[0052] Additionally, in describing this disclosure, detailed descriptions of relevant known elements or functions are omitted here where such descriptions would obscure the key subject matter of the disclosure.

[0053] Ordinal terms such as “first” and “second” can be used to distinguish one element from another among various elements, but are not intended to limit the elements by means of the term.

[0054] Throughout the specification, when a section is referred to as “comprising” or “including” any element, unless otherwise expressly stated, this means that the section may further include other elements, without excluding other elements.

[0055] Furthermore, the term "control unit" as described in the specification refers to a unit that processes at least one function or operation, and can be implemented by hardware, software, or a combination of hardware and software.

[0056] Furthermore, throughout the specification, when one part is referred to as "connected" to another part, this is not limited to the case where they are "directly connected," but includes the case where they are "indirectly connected" and another element is placed between them.

[0057] In the following, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0058] Figure 1 The diagram schematically illustrates a battery management device 100 according to an embodiment of the present disclosure.

[0059] Reference Figure 1 According to embodiments of the present disclosure, the battery management device 100 may include a curve generation unit 110, a curve conversion unit 120, and a control unit 130.

[0060] The curve generation unit 110 can be configured to acquire battery information including the voltage V and capacity Q of the battery cell B.

[0061] Here, battery cell B refers to a single, physically separable unit that includes a negative terminal and a positive terminal. For example, a pouch-type lithium polymer battery can be considered as battery cell B.

[0062] For example, the curve generation unit 110 can be configured to communicate with an external source. Additionally, the curve generation unit 110 can receive battery information from an external source.

[0063] The curve generation unit 110 can be configured to generate a battery curve representing the correspondence between voltage and capacity based on the acquired battery information.

[0064] Specifically, the curve generation unit 110 can generate a battery curve by mapping the corresponding voltages and capacities in the acquired battery information.

[0065] For example, curve generation unit 110 can generate battery curves in tabular form, mapping corresponding voltages and capacities in the table. As another example, curve generation unit 110 can generate battery curves in the form of a planar graph in which corresponding voltages and capacities are mapped. That is, the battery curves generated by curve generation unit 110 can be represented in various forms, as long as they can represent the correspondence between voltage and capacity.

[0066] The curve conversion unit 120 can be configured to receive the battery curve from the curve generation unit 110.

[0067] Specifically, the curve conversion unit 120 and the curve generation unit 110 can be connected by wired or wireless means to enable communication between them. Additionally, the curve conversion unit 120 can receive the battery curve from the curve generation unit 110 via a wired line or a wireless communication network.

[0068] The curve conversion unit 120 can be configured to convert the received battery curve into a differential curve representing the correspondence between voltage and differential capacity for that voltage.

[0069] Here, the differential capacity is a value obtained by differentiating the capacity with respect to the voltage and the capacity, and can be expressed as "dQ / dV". Furthermore, the unit of differential capacity can be [mAh / V]. In other words, the curve conversion unit 120 can convert the battery curve received from the curve generation unit 110 into a differential curve.

[0070] Figure 2 This is a schematic diagram of the first differential curve PF1 according to an embodiment of the present disclosure.

[0071] Specifically Figure 2 The first differential curve PF1 can be the differential curve of battery cell B in the BOL (Start of Life) state. That is, curve conversion unit 120 can receive the battery curve of battery cell B in the BOL state from curve generation unit 110 and convert the received battery curve into the first differential curve PF1.

[0072] In the following text, for ease of explanation, note that the XY plane plot, in which voltage is set as the X-axis and differential capacitance as the Y-axis, is described as a differential curve.

[0073] The control unit 130 can be configured to acquire multiple differential curves PF1 to PF7 of the battery cell B converted by the curve conversion unit 120.

[0074] Here, the multiple differential curves PF1 to PF7 can be differential curves that are transformed in each cycle of multiple cycles of battery cell B.

[0075] For example, the control unit 130 can communicate with the curve conversion unit 120 via wired or wireless connection. Additionally, the control unit 130 can receive multiple differential curves PF1 to PF7 from the curve conversion unit 120.

[0076] In the following description, for ease of explanation, it will be described that the control unit 130 acquires differential curves for battery cell B, which has been used 1800 cycles, starting from the BOL state at intervals of 300 cycles. However, it should be noted that the cycle interval for generating battery curves by curve generation unit 110 and converting battery curves into differential curves by curve conversion unit 120 is not limited to only 300 cycles. For example, curve generation unit 110 may generate battery curves every cycle, and curve conversion unit 120 may convert all battery curves generated in each cycle into differential curves. In addition, curve conversion unit 120 may send the converted differential curves to control unit 130 immediately upon completion of the differential curve conversion, or acquire a certain number of differential curves and then send multiple acquired differential curves PF1 to PF7 to control unit 130.

[0077] Figure 3 The diagram schematically illustrates the first differential curve PF1 to the seventh differential curve PF7 according to an embodiment of the present disclosure.

[0078] For example, in Figure 3 In this implementation, the first differential curve PF1 can be the differential curve of battery cell B in the BOL state, and the second differential curve PF2 can be the differential curve of battery cell B after 300 cycles. Furthermore, the third differential curve PF3 can be the differential curve of battery cell B after 600 cycles, and the fourth differential curve PF4 can be the differential curve of battery cell B after 900 cycles. Additionally, the fifth differential curve PF5 is the differential curve of battery cell B after 1200 cycles, the sixth differential curve PF6 is the differential curve of battery cell B after 1500 cycles, and the seventh differential curve PF7 is the differential curve of battery cell B after 1800 cycles.

[0079] The control unit 130 can be configured to select a peak value from each of the multiple acquired differential curves PF1 to PF7 that includes a preset standard voltage region.

[0080] Specifically, the control unit 130 can select the peak value with the minimum differential capacity and the instantaneous rate of change of differential capacity relative to voltage of each of the multiple differential curves PF1 to PF7 within the standard voltage region.

[0081] More specifically, a peak value can be the point in the standard voltage region where the instantaneous rate of change of the differential capacitance with respect to voltage is 0 and the differential capacitance is minimum. Furthermore, based on the peak value, the instantaneous rate of change (the instantaneous rate of change of the differential capacitance with respect to voltage) can be negative at low voltages, while it can be positive at high voltages. In other words, a peak value can be a point with a downwardly convex shape in the XY plane.

[0082] In addition, the standard voltage region can be preset to a portion of the voltage region of battery cell B near the discharge termination.

[0083] Specifically, the standard voltage region can be set to the voltage range where the peak value of battery cell B occurs. That is, generally speaking, the peak value of battery cell B occurs near the discharge end of battery cell B, and the peak voltage of a degraded battery cell B is not significantly different from the peak voltage of a battery cell B in the BOL state. Therefore, the standard voltage region can be set to include the voltage range where the peak value of battery cell B in the BOL state occurs. For example, the standard voltage region can be preset to a voltage range of 3.3 [V] to 3.5 [V].

[0084] Figure 4This is an enlarged view showing a portion of the first differential curves PF1 to the seventh differential curves PF7 according to an embodiment of the present disclosure.

[0085] Specifically Figure 4 This is an enlarged view showing a portion of the standard voltage region in the first differential curve PF1 to the seventh differential curve PF7. More specifically, Figure 4 This is an enlarged view showing the voltage region of 3.35 [V] to 3.5 [V] in the first differential curve PF1 to the seventh differential curve PF7.

[0086] For example, in Figure 4 In this implementation, the control unit 130 can select a first peak P1 from the first differential curve PF1 and a second peak P2 from the second differential curve PF2. Additionally, the control unit 130 can select a third peak P3 from the third differential curve PF3 and a fourth peak P4 from the fourth differential curve PF4. Finally, the control unit 130 can select a fifth peak P5 from the fifth differential curve PF5, a sixth peak P6 from the sixth differential curve PF6, and a seventh peak P7 from the seventh differential curve PF7.

[0087] The control unit 130 can be configured to determine the voltage variation pattern and differential capacity variation pattern of a plurality of selected peak voltages P1 to P7.

[0088] Specifically, the control unit 130 can be configured to determine the voltage change pattern and differential capacity change pattern of each pair of corresponding peaks among the plurality of peaks P1 to P7. Preferably, the control unit 130 can determine the voltage change pattern and differential capacity change pattern of the plurality of peaks P1 to P7 according to the cycle sequence of the battery cell B.

[0089] For example, the control unit 130 can divide the peak pairs into a first peak P1 and a second peak P2, a second peak P2 and a third peak P3, a third peak P3 and a fourth peak P4, a fourth peak P4 and a fifth peak P5, a fifth peak P5 and a sixth peak P6, a sixth peak P6 and a seventh peak P7, and determine the voltage change mode and differential capacity change mode of each divided peak pair.

[0090] Here, the voltage variation pattern can refer to the pattern in which the peak voltage changes as the cycle life of battery cell B increases. Additionally, the differential capacity variation pattern can refer to the pattern in which the differential capacity of the peak value changes as the cycle life of battery cell B increases.

[0091] exist Figure 4In the implementation, the voltage change pattern from the first peak to the third peak P1, P2, P3 can be an increasing pattern, the voltage change pattern between the third peak P3 and the fourth peak P4 can be a decreasing pattern, and the voltage change pattern from the fourth peak P4 to the seventh peak P7 can be an increasing pattern.

[0092] In addition, Figure 4 In the implementation of the method, the differential capacity change pattern between the first peak P1 and the second peak P2 can be a decreasing pattern, while the differential capacity change pattern from the second peak P2 to the seventh peak P7 can be an increasing pattern.

[0093] The control unit 130 can be configured to determine whether the degradation of battery cell B is accelerated based on whether the determined voltage change pattern corresponds to a preset first reference pattern and whether the determined differential capacity change pattern corresponds to a preset second reference pattern.

[0094] Here, the first reference mode can be configured such that the voltage increases towards a higher voltage to be equal to or greater than a preset standard voltage. For example, the standard voltage can be preset to 3 [mV]. That is, the first reference mode can be a mode in which the voltage between two peaks corresponding to the cycle sequence increases towards a higher voltage as the battery cell B cycles, and the two voltages differ by more than 3 [mV].

[0095] Specifically, the control unit 130 can be configured to determine whether the voltage change mode corresponds to the first reference mode by judging whether the determined voltage change mode is an increasing mode and whether the voltage difference between the corresponding peaks is equal to or greater than the standard voltage.

[0096] For example, in Figure 4 In this implementation, the voltage variation patterns from the first peak to the third peak P1, P2, P3 and from the fourth peak to the seventh peak P4, P5, P6, P7 are increasing patterns. However, the voltage differences between the first peak P1 and the second peak P2, the second peak P2 and the third peak P3, and the fourth peak P4 and the fifth peak P5 may be less than the standard voltage. Furthermore, the voltage differences between the fifth peak P5 and the sixth peak P6, and between the sixth peak P6 and the seventh peak P7, may be greater than or equal to the standard voltage. Therefore, the control unit 130 can determine that the voltage variation patterns from the fifth peak to the seventh peak P5, P6, P7 correspond to the first reference pattern.

[0097] In other words, due to various internal and / or external factors, the voltage and capacity measured for battery cell B may contain errors. Furthermore, this error can also be reflected in the voltage peaks contained in the differential curve based on battery information. Therefore, the control unit 130 can determine whether the voltage change patterns of the multiple peaks P1 to P7 correspond to the first reference mode by first considering whether the voltage change pattern is an increasing mode, and then considering whether the voltage difference between the corresponding peaks is equal to or greater than the standard voltage.

[0098] In addition, the second reference mode can be configured to increase the determined differential capacity.

[0099] Specifically, the control unit 130 can be configured to determine whether the differential capacity change mode corresponds to the second reference mode by judging whether the differential capacity change mode is an increasing mode.

[0100] For example, in Figure 4 In this implementation, the differential capacity variation pattern from the second peak P2 to the seventh peak P7 is an increasing pattern. Therefore, the control unit 130 can determine that the differential capacity variation pattern from the second peak P2 to the seventh peak P7 corresponds to the second reference pattern.

[0101] Furthermore, through this process, if the voltage change mode corresponds to the first reference mode and the differential capacity change mode corresponds to the second reference mode, the control unit 130 can determine that the state of battery cell B is in an accelerated degradation state.

[0102] Here, the accelerated degradation state refers to the accelerated degradation state of battery cell B.

[0103] Generally, battery cell B degrades as the battery is cycled. With prolonged use, the degradation rate of battery cell B can gradually increase. For example, even over the same period, the degree of degradation of battery cell B from the first time point in the BOL state to the second time point and the degree of degradation of battery cell B from the Nth time point in the MOL (Mid-Life) state to the N+1th time point can differ. If the degradation of battery cell B accelerates as described above, it is necessary to appropriately control battery cell B to slow down its degradation; therefore, accurately determining whether the state of battery cell B is in a state of accelerated degradation is crucial.

[0104] Therefore, the battery management device 100 according to the embodiments of the present disclosure has the following advantages: by considering both the voltage change pattern and the differential capacity change pattern of the multiple peaks P1 to P7 contained in the multiple differential curves PF1 to PF7, it can accurately determine whether the state of the battery cell B is in an accelerated deterioration state.

[0105] Furthermore, the control unit 130 provided to the battery management device 100 according to embodiments of the present disclosure may optionally include processors, application-specific integrated circuits (ASICs), other chipsets, logic circuits, registers, communication modems, data processing devices, etc., known in the art, to execute various control logics performed in this disclosure. Moreover, when the control logic is implemented in software, the control unit 130 can be implemented as a set of program modules. In this case, the program modules can be stored in memory and executed by the control unit 130. The memory can be located internally or externally to the control unit 130 and can be connected to the control unit 130 by various known means.

[0106] Additionally, the battery management device 100 according to embodiments of this disclosure may further include a storage unit 140. The storage unit 140 may store programs and data required by the battery management device 100 to determine the accelerated degradation of battery cell B. That is, the storage unit 140 may store data required for the operation and function of each component of the battery management device 100, data generated during the execution of operations or functions, etc. The storage unit 140 is not particularly limited in type, as long as it is a known information storage device capable of recording, erasing, updating, and retrieving data. As examples, the information storage device may include RAM, flash memory, ROM, EEPROM, registers, etc. Furthermore, the storage unit 140 may store program code defining the processes executable by the curve generation unit 110, curve conversion unit 120, and control unit 130.

[0107] For example, storage unit 140 can store differential curves converted by curve conversion unit 120. If multiple differential curves are stored in storage unit 140, control unit 130 can access storage unit 140 to obtain multiple differential curves PF1 to PF7. That is, control unit 130 can directly obtain multiple differential curves PF1 to PF7 from curve conversion unit 120, or it can obtain multiple differential curves PF1 to PF7 stored in storage unit 140 by accessing storage unit 140.

[0108] The control unit 130 can be configured to determine at least one target peak TP1, TP2 among a plurality of peaks P1 to P7, where the voltage variation mode corresponds to a first reference mode and the differential capacity variation mode corresponds to a second reference mode.

[0109] For example, in Figure 4In this implementation, the voltage variation pattern of the fifth peak P5 to the seventh peak P7 can correspond to the first reference mode, and the differential capacitance variation pattern of the third to seventh peaks P3 to P7 can correspond to the second reference mode. Therefore, the control unit 130 can determine the sixth peak P6 and the seventh peak P7 as target peaks. That is, the control unit 130 can determine the sixth peak P6 as the first target peak TP1 and the seventh peak P7 as the second target peak TP2.

[0110] Additionally, the control unit 130 can be configured to determine that the degradation of battery cell B begins to accelerate from the lowest cycle among cycles corresponding to at least one target peak.

[0111] For example, in Figure 4 In this implementation, the control unit 130 can determine that the degradation of battery cell B begins to accelerate from 1500 cycles corresponding to the first target peak TP1. That is, the control unit 130 can determine that battery cell B degrades even before 1200 cycles corresponding to the fifth peak P5, but the state of battery cell B is not in an accelerated degradation state before 1200 cycles.

[0112] In other words, the battery management device 100 has the following advantages: it not only determines whether the state of battery cell B is in an accelerated degradation state, but also determines the cycle of accelerated degradation of battery cell B. Therefore, the battery management device 100 can control battery cell B by considering the accelerated degradation cycle and the state of battery cell B, thereby slowing down the degradation of battery cell B. As a result, since the degradation progress of battery cell B is slowed down, the service life of battery cell B can be increased.

[0113] In the above text, based on Figure 3 and Figure 4 The implementation method described above uses the differential curve of battery cell B acquired every 300 cycles to determine the state of battery cell B and the time point of accelerated degradation. However, to more accurately determine the state of battery cell B and the time point of accelerated degradation, the battery management device 100 can set a shorter cycle interval for acquiring the differential curve. For example, if the battery management device 100 determines the state of battery cell B and the time point of accelerated degradation based on the differential curve of battery cell B acquired every 1 cycle, the state of battery cell B and the time point of accelerated degradation can be determined more accurately.

[0114] In the following text, various implementations will be described in which the battery management device 100 can determine the state of the battery cell B as an accelerated degradation state based on the voltage change mode and the differential capacity change mode.

[0115] Figure 5This is an enlarged view showing another portion of the first differential curves PF1 to the seventh differential curves PF7 according to an embodiment of the present disclosure. Figure 6 This is an enlarged view showing a portion of the first differential curves PF1 to the seventh differential curves PF7 according to an embodiment of the present disclosure.

[0116] Specifically Figure 5 It is shown Figure 3 An enlarged view of the voltage region from approximately 3.85 [V] to 4.1 [V] in the first differential curve PF1 to the seventh differential curve PF7. Additionally, Figure 6 It is shown in Figure 3 An enlarged view of the voltage region from approximately 3.5 [V] to approximately 3.7 [V] of the first differential curve PF1 to the seventh differential curve PF7.

[0117] Reference Figure 5 It can be seen that after 300 cycles, as battery cell B cycles, the voltage at the same differential capacity gradually decreases. Additionally, referring to... Figure 6 It can be seen that as battery cell B cycles, the differential capacity of the multiple peaks contained in the voltage region of 3.5 [V] to 3.6 [V] of the first differential curve PF1 to the seventh differential curve PF7 increases, and the voltage of the multiple peaks shifts towards lower voltages. Figure 6 In this context, multiple peaks refer to the points marked with "●" in each of the first differential curve PF1 to the seventh differential curve PF7.

[0118] In other words, referencing Figure 3 , Figure 5 and Figure 6 As battery cell B is cycled, its usable capacity gradually decreases, thus demonstrating that battery cell B deteriorates with each cycle. For example, in... Figure 3 In the implementation method, when integrating the differential curve based on the differential capacity 0 [mAh / V], the integration area can be the usable capacity of battery cell B. Therefore, according to Figure 3 , Figure 5 and Figure 6 Battery cell B is in a state of deterioration as the cycle progresses.

[0119] Figure 7 This is a schematic diagram illustrating the coulombic efficiency of battery cell B in each cycle of accelerated degradation as determined by a battery management device 100 according to an embodiment of the present disclosure.

[0120] Here, coulombic efficiency (CE) is calculated for each cycle based on the amount of charge calculated from the coulomb count while battery cell B is charging and the amount of discharge calculated from the coulomb count while battery cell B is discharging. Specifically, coulombic efficiency can be calculated using the formula "discharge amount ÷ charge amount × 100" for each cycle.

[0121] Reference Figure 7 The coulombic efficiency (COP) increases from BOL (0 cycles) to 600 cycles, remains stable from 600 to 1500 cycles, but decreases from 1500 to 1800 cycles. This means that the COP decreases from 1500 to 1800 cycles because the degradation of cell B begins to accelerate from 1500 cycles.

[0122] Therefore, refer to Figure 7 The battery management device 100 according to the embodiments of this disclosure has the advantage that, without calculating the coulombic efficiency of battery cell B in each cycle, it accurately determines whether the state of battery cell B is in an accelerated degradation state based on the voltage change pattern and differential capacity change pattern of the peak values ​​contained in multiple differential curves PF1 to PF7. Furthermore, the battery management device 100 has the advantage of determining the cycle point of accelerated degradation of battery cell B.

[0123] Figure 8 This is a diagram schematically showing multiple differential voltage curves PF1′ to PF7′ that represent the relationship between the capacity and differential voltage of battery cell B.

[0124] Here, the differential voltage is the value obtained by differentiating the voltage from the capacity, and can be expressed as "dV / dQ". Furthermore, the unit of the differential voltage can be [V / mAh]. That is to say, since the differential voltage curve represents the relationship between the differential voltage and capacity of battery cell B, it should be noted that the differential voltage curve is related to... Figure 3 Different curves of differential curves.

[0125] Specifically Figure 8 This is a graph showing the first differential voltage curve PF1′ to the seventh differential voltage curve PF7′. Figure 8In this diagram, the first differential voltage curve PF1′ can be the differential voltage curve of battery cell B in the BOL state, and the second differential voltage curve PF2′ can be the differential voltage curve of battery cell B after 300 cycles. Furthermore, the third differential voltage curve PF3′ can be the differential voltage curve of battery cell B after 600 cycles, and the fourth differential voltage curve PF4′ can be the differential voltage curve of battery cell B after 900 cycles. Additionally, the fifth differential voltage curve PF5′ can be the differential voltage curve of battery cell B after 1200 cycles, the sixth differential voltage curve PF6′ can be the differential voltage curve of battery cell B after 1500 cycles, and the seventh differential voltage curve PF7′ can be the differential voltage curve of battery cell B after 1800 cycles.

[0126] For example, in Figure 8 As can be seen from the data, as the number of cycles of battery cell B increases, the curvature decreases in the order of the first differential voltage curve PF1′ to the seventh differential voltage curve PF7′, thus making the curvature flatter.

[0127] Furthermore, if the curvature difference between the two differential voltage curves is compared in cyclic order, it can be seen that the curvature difference between the fifth differential voltage curve PF5′ and the sixth differential voltage curve PF6′ is the largest.

[0128] Specifically, refer to Figure 8 In the box shown by the dashed line, the curvature between the fifth differential voltage curve PF5′ and the sixth differential voltage curve PF6′ is the largest. That is to say, it can be seen that among the curvature differences between the first and second differential voltage curves PF1′ and PF2′, the second and third differential voltage curves PF2′ and PF3′, the third and fourth differential voltage curves PF3′ and PF4′, the fourth and fifth differential voltage curves PF4′ and PF5′, the fifth and sixth differential voltage curves PF5′ and PF6′, and the sixth and seventh differential voltage curves PF6′, the curvature difference between the fifth and sixth differential voltage curves PF6′ is the largest.

[0129] Specifically, such as Figure 8 As shown, the fact that the curvature of the differential voltage curve flattens out with the progress of cycling can be explained by the increase in the internal resistance of battery cell B due to the degradation of battery cell B. In other words, if the internal resistance of battery cell B increases significantly starting from 1500 cycles, it can be said that the degradation of battery cell B accelerates starting from 1500 cycles.

[0130] Therefore, even if reference Figure 8The battery management device 100 according to the embodiments of this disclosure has the advantage of accurately determining whether the state of battery cell B is in an accelerated degradation state. Furthermore, the battery management device 100 has the advantage of determining the cycle point of accelerated degradation of battery cell B.

[0131] The control unit 130 can be configured to set the discharge termination voltage of battery cell B to be greater than or equal to the voltage corresponding to at least one target peak TP1, TP2.

[0132] Specifically, if battery cell B is in a state of accelerated degradation, control unit 130 can reduce the usable voltage range of battery cell B by increasing the discharge termination voltage of battery cell B. This is because even if battery cell B degrades, if it is discharged to a low voltage region, the degradation of battery cell B can continue to accelerate. Therefore, control unit 130 can slow down the degradation rate of battery cell B by increasing the discharge termination voltage of battery cell B.

[0133] For example, in Figure 4 In this implementation, the control unit 130 can determine the sixth peak P6 as the first target peak TP1 and the seventh peak P7 as the second target peak TP2. Additionally, the control unit 130 can set the discharge termination voltage of battery cell B to be greater than or equal to the voltage corresponding to the first target peak TP1 or the voltage corresponding to the second target peak TP2.

[0134] Preferably, the control unit 130 can be configured to set the discharge termination voltage of the battery cell B to be greater than or equal to the maximum voltage among the voltages corresponding to at least one target peak TP1, TP2.

[0135] For example, in Figure 4 In this embodiment, the control unit 130 can set the discharge termination voltage of battery cell B to be greater than or equal to the voltage corresponding to the second target peak value TP2. More preferably, the control unit 130 can set the discharge termination voltage of battery cell B to a value greater than the voltage corresponding to the second target peak value TP2.

[0136] Therefore, the battery management device 100 according to the embodiments of the present disclosure has the following advantages: it not only determines the state of the battery cell B, but also increases the lifespan of the battery cell B by controlling the discharge termination voltage of the battery cell B upward.

[0137] The battery management device 100 according to this disclosure can be applied to a BMS (Battery Management System). That is, the BMS according to this disclosure can include the aforementioned battery management device 100. In this configuration, at least some of the components of the battery management device 100 can be implemented by supplementing or adding the functionality of components included in a conventional BMS. For example, the curve generation unit 110, curve conversion unit 120, control unit 130, and storage unit 140 of the battery management device 100 can be implemented as components of a BMS.

[0138] Furthermore, the battery management device 100 according to this disclosure can be provided to the battery pack 1. That is, the battery pack 1 according to this disclosure may include the aforementioned battery management device 100 and at least one battery cell B. In addition, the battery pack 1 may also include electrical equipment (relays, fuses, etc.) and a housing.

[0139] Figure 9 This is a diagram schematically illustrating an exemplary configuration of a battery pack 1 including a battery management device 100 according to an embodiment of the present disclosure.

[0140] Reference Figure 9 The battery pack 1 includes a positive terminal and a negative terminal, and may include a battery cell B, a measurement unit 200 and a battery management device 100.

[0141] The measuring unit 200 can be configured to measure the voltage and capacity of the battery cell B.

[0142] Specifically, the measuring unit 200 can measure the voltage of the battery by measuring the voltage across the two terminals of the battery cell B. Furthermore, the measuring unit 200 can measure the current output from the battery cell B and the discharge time while the battery cell B is discharging. Additionally, the measuring unit 200 can measure the capacity of the battery cell B based on the measured current and discharge time.

[0143] For example, in Figure 9 In this embodiment, the measurement unit 200 can be connected to a first sensing line SL1, a second sensing line SL2, and a third sensing line SL3. The measurement unit 200 can measure the voltage of battery cell B through the first sensing line SL1 and the second sensing line SL2. Additionally, the measurement unit 200 can be connected to a current measurement unit A through the third sensing line SL3, and the current of battery cell B can be measured through the current measurement unit A. Preferably, the measurement unit 200 may include a timer capable of measuring the discharge time simultaneously with the current of battery cell B.

[0144] In addition, the charging / discharging unit 2 can be connected to the positive terminal (P+) and negative terminal (P-) of the battery pack 1 to charge or discharge the battery cell B.

[0145] For example, when battery cell B is discharged by charging / discharging unit 2, measurement unit 200 can measure the voltage and capacity of battery cell B and send battery information including the measured voltage and capacity to curve generation unit 110. That is, curve generation unit 110 can obtain battery information by receiving battery information from measurement unit 200.

[0146] Figure 10 This diagram schematically illustrates a battery management method according to another embodiment of the present disclosure. Each step of the battery management method can be performed by a battery management device 100.

[0147] In the following text, it should be noted that, for ease of description, content that overlaps with the previously described content will be simply described or omitted.

[0148] Reference Figure 10 The battery management method may include: a battery information acquisition step (S100), a battery curve generation step (S200), a differential curve conversion step (S300), a peak selection step (S400), a mode determination step (S500), and a degradation acceleration determination step (S600).

[0149] The battery information acquisition step (S100) is a step of acquiring battery information including the voltage and capacity of battery cell B, and can be performed by the curve generation unit 110.

[0150] For example, the curve generation unit 110 can receive battery information from an external source, or the battery information can be directly input into the curve generation unit 110 by the user. Preferably, refer to Figure 9 In this implementation, the curve generation unit 110 can obtain battery information from the measurement unit 200, which is capable of measuring the voltage and capacity of the battery cell B.

[0151] The curve generation step (S200) is a step of generating a battery curve representing the correspondence between voltage and capacity based on the acquired battery information, and can be executed by the curve generation unit 110.

[0152] Specifically, the curve generation unit 110 can read the corresponding voltage and capacity from the acquired battery information and generate a battery curve representing the correspondence between the read voltage and capacity.

[0153] The differential curve conversion step (S300) is a step of converting the battery curve into a differential curve that represents the correspondence between voltage and differential capacity for that voltage, and can be performed by the curve conversion unit 120.

[0154] Specifically, the curve conversion unit 120 can receive the battery curve from the curve generation unit 110. Furthermore, the curve conversion unit 120 can convert the battery curve into a differential curve representing the relationship between voltage and differential capacity.

[0155] The peak selection step (S400) is a step of selecting the peak value included in the preset standard voltage region from each of the multiple differential curves PF1 to PF7 converted in the differential curve conversion step (S300), and can be executed by the control unit 130.

[0156] For example, in Figure 4 In one implementation, the control unit 130 can select the first peak value P1 to the seventh peak value P7 respectively within the standard voltage range of the first differential curve PF1 to the seventh differential curve PF7.

[0157] The mode determination step (S500) is a step of determining the voltage change mode of the voltages of the multiple selected peaks P1 to P7 and the differential capacity change mode of the differential capacity, and can be executed by the control unit 130.

[0158] Preferably, the control unit 130 can determine the voltage change pattern and differential capacity change pattern of multiple peaks P1 to P7 according to the cycle sequence of the battery cell B.

[0159] For example, in Figure 4 In this implementation, the voltage change pattern from the first peak P1 to the third peak P3 can be an increasing pattern, the voltage change pattern between the third peak P3 and the fourth peak P4 can be a decreasing pattern, and the voltage change pattern from the fourth peak P4 to the seventh peak P7 can be an increasing pattern. Additionally, the differential capacitance change pattern between the first peak P1 and the second peak P2 can be a decreasing pattern, while the differential capacitance change pattern from the second peak P2 to the seventh peak P7 can be an increasing pattern.

[0160] The degradation acceleration determination step (S600) is a step of determining whether the degradation of battery cell B is accelerated based on whether the determined voltage change pattern corresponds to a preset first reference pattern and whether the determined differential capacity change pattern corresponds to a preset second reference pattern, and can be executed by control unit 130.

[0161] If the voltage change mode corresponds to the first reference mode and the differential capacity change mode corresponds to the second reference mode, then the control unit 130 can determine that the state of battery cell B is a state of accelerated degradation.

[0162] Furthermore, the control unit 130 can be configured to determine at least one target peak TP1, TP2 among a plurality of peaks P1 to P7, corresponding to the first reference mode and the second reference mode. Additionally, the control unit 130 can be configured to determine that the degradation of battery cell B begins to accelerate from the lowest cycle among the cycles corresponding to at least one target peak TP1, TP2.

[0163] In other words, the control unit 130 can not only determine whether the state of battery cell B is in an accelerated deterioration state, but also determine the cycle of accelerated deterioration of battery cell B.

[0164] In addition, the control unit 130 can increase the lifespan of battery cell B by setting the discharge termination voltage of battery cell B to be greater than or equal to the maximum voltage among the voltages corresponding to at least one target peak TP1, TP2.

[0165] The embodiments of this disclosure described above can be implemented not only by devices and methods, but also by a program that implements functions corresponding to the configuration of the embodiments of this disclosure, or a recording medium on which the program is recorded. Those skilled in the art can readily implement the program or recording medium based on the above description of the embodiments.

[0166] This disclosure has been described in detail. However, it should be understood that while the detailed description and specific examples represent preferred embodiments of this disclosure, they are given by way of example only, as various variations and modifications within the scope of this disclosure will become apparent to those skilled in the art from this detailed description.

[0167] Additionally, those skilled in the art can make many substitutions, modifications and variations to the above-described disclosure without departing from the technical solution of the disclosure, and the disclosure is not limited to the above embodiments and drawings, and each embodiment can be selectively combined in part or in whole to allow for various modifications.

Claims

1. A battery management device, the battery management device comprising: A curve generation unit is configured to: acquire battery information including the voltage and capacity of battery cells and generate a battery curve representing the correspondence between the voltage and the capacity based on the acquired battery information; A curve conversion unit is configured to receive the battery curve from the curve generation unit and convert the received battery curve into a differential curve representing the correspondence between the voltage and the differential capacity of the voltage; as well as A control unit is configured to: acquire multiple differential curves of the battery cell converted by the curve conversion unit; select peak values ​​included in a preset standard voltage region from each of the acquired differential curves; determine the voltage variation pattern of the selected peak values ​​and the differential capacity variation pattern of the differential capacity; and determine whether the degradation of the battery cell is accelerated based on whether the determined voltage variation pattern corresponds to a preset first reference pattern and whether the determined differential capacity variation pattern corresponds to a preset second reference pattern. The multiple differential curves are differential curves that are transformed in each cycle of multiple cycles for the battery cell.

2. The battery management device according to claim 1, in, The control unit is configured to determine the voltage variation mode and the differential capacity variation mode for each pair of peaks that correspond to each other among the plurality of peaks.

3. The battery management device according to claim 2, in, The first reference mode is configured such that the voltage increases toward a higher voltage to be equal to or greater than a preset standard voltage, and The control unit is configured to determine whether the voltage change mode corresponds to the first reference mode by judging whether the determined voltage change mode is an increasing mode and whether the voltage difference between the two corresponding peaks is equal to or greater than the standard voltage.

4. The battery management device according to claim 2, in, The second reference mode is configured as the differential capacity increase mode, and The control unit is configured to determine whether the determined differential capacity change mode corresponds to the second reference mode by judging whether the determined differential capacity change mode is an increasing mode.

5. The battery management device according to claim 1, in, The control unit is configured to determine the voltage variation pattern and the differential capacity variation pattern for the plurality of peak values ​​based on the cycle sequence of the battery cells.

6. The battery management device according to claim 5, in, If the voltage change pattern corresponds to the first reference pattern and the differential capacity change pattern corresponds to the second reference pattern, then the control unit determines that the state of the battery cell is an accelerated degradation state, which indicates that the battery cell is in an accelerated degradation state.

7. The battery management device according to claim 5, in, The control unit is configured to: determine at least one target peak among the plurality of peaks, where the voltage variation pattern corresponds to the first reference pattern and the differential capacity variation pattern corresponds to the second reference pattern.

8. The battery management device according to claim 7, in, The control unit is configured to determine that the degradation of the battery cell begins to accelerate from the lowest cycle among the cycles corresponding to the at least one target peak value.

9. The battery management device according to claim 7, in, The control unit is configured to set the discharge termination voltage of the battery cell to be equal to or greater than the voltage corresponding to the at least one target peak value.

10. The battery management device according to claim 1, in, The standard voltage region is preset to be a portion of the voltage region of the battery cell near the discharge termination.

11. The battery management device according to claim 1, in, The peak value is the point in the standard voltage region where the instantaneous rate of change of the differential capacity with respect to voltage is 0 and the differential capacity is at its minimum.

12. A battery pack comprising a battery management device according to any one of claims 1 to 11.

13. A battery management method, the battery management method comprising the following steps: The battery information acquisition step acquires battery information including the voltage and capacity of the battery cells. A battery curve generation step, which generates a battery curve representing the correspondence between the voltage and the capacity based on the acquired battery information; The differential curve conversion step converts the generated battery curve into a differential curve representing the correspondence between the voltage and the differential capacity for that voltage. A peak selection step, which selects a peak value that is included in a preset standard voltage region from each differential curve converted in the differential curve conversion step; The mode determination step determines the voltage variation pattern of the voltage of multiple selected peak values ​​and the differential capacity variation pattern of the differential capacity. as well as The degradation acceleration determination step determines whether the degradation of the battery cell is accelerated based on whether the determined voltage change pattern corresponds to a preset first reference pattern and whether the determined differential capacity change pattern corresponds to a preset second reference pattern. The differential curve is a differential curve that is transformed in each cycle of multiple cycles for the battery cell.

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