Apparatus and method for diagnosing battery

Abstract

An apparatus for diagnosing a battery according to one embodiment of the present disclosure includes: a curve obtaining unit configured to obtain a charging curve indicating a voltage change of the battery during a charging process according to a charging protocol in which a correspondence relationship between a charging C-rate and a maximum allowable SOC is preset; and a control unit configured to calculate a voltage change amount of the battery at a charging start point of the charging curve, calculate a target resistance of the battery based on the calculated voltage change amount, and diagnosing the state of the battery by comparing the target resistance with a first resistance curve in which the target resistance of the battery calculated in each previous charging cycle is stored.

Description

TECHNICAL FIELD

[0001] This application is based on and claims priority to Korean Patent Application No. 10-2024-0070935, filed on May 30, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

[0002] The disclosure relates to an apparatus and method for diagnosing a battery, and more particularly, to an apparatus and method for diagnosing a state of a battery based on electrical resistance generated during a charging process. BACKGROUND

[0003] Recently, the demand for portable electronic products such as notebook computers, camcorders, and portable phones has sharply increased, and electric vehicles, energy storage batteries, robots, satellites, etc. have been developed vigorously. Accordingly, high-performance batteries that allow repeated charging and discharging are being actively researched.

[0004] Currently marketed batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, etc. Among them, lithium batteries are attracting attention because they have almost no memory effect compared to nickel-based batteries, allow free charging and discharging, and also have a very low self-discharge rate and high energy density.

[0005] Although many studies are being conducted on these batteries in terms of high capacity and high density, improving lifespan and safety is also important. In order to improve battery safety, a technology that accurately diagnoses the current state of the battery is required.

[0006] In particular, a phenomenon in which lithium is deposited on the surface of the negative electrode (lithium plating) needs to be prevented. If lithium is deposited on the surface of the negative electrode, it causes a side reaction with the electrolyte and a change in the kinetic balance of the battery, which leads to battery degradation.

[0007] In addition, lithium plating can cause swelling of the battery. When swelling occurs in the battery, the center of the battery swells more than the edge of the battery, which can cause uneven pressure distribution in the battery. This can cause problems such as a decrease in battery performance and a sudden failure phenomenon in which the electrical connection is instantaneously disconnected. SUMMARY

[0008] TECHNICAL PROBLEM

[0009] The disclosure is designed to solve the problems of the related art, and thus, the disclosure aims to provide an apparatus and method for diagnosing a battery that diagnoses the state of a battery having a sudden failure risk based on the electrical resistance of the battery calculated during charging.

[0010] These and other objects and advantages of the present disclosure can be understood from the following detailed description, and will become more fully apparent when the exemplary embodiments of the present disclosure are considered in conjunction with the accompanying drawings. Further, it will be easy for those skilled in the art to understand that the objects and advantages of the present disclosure can be achieved by the means shown in the appended claims and combinations thereof.

[0011] Technical Solution

[0012] An apparatus for diagnosing a battery according to one aspect of the present disclosure can include a curve obtaining unit configured to obtain a charging curve representing a voltage change of the battery in a charging process according to a charging protocol in which a correspondence between a charging C-rate and a maximum allowable SOC is preset, and a control unit configured to calculate an amount of voltage change of the battery at a charging start point of the charging curve, calculate a target resistance of the battery based on the calculated amount of voltage change, and diagnose a state of the battery by comparing the target resistance with a first resistance curve in which target resistances of the battery calculated in each previous charging cycle are stored.

[0013] The control unit can be configured to change the charging protocol when the state of the battery is diagnosed as an abnormal state.

[0014] The control unit can be configured to obtain an SOC-resistance curve representing a correspondence between an SOC (State of Charge) of the battery charged while a charging period and a rest period are repeated at each charging C-rate included in the charging protocol and a resistance of the rest period, and change a maximum allowable SOC corresponding to each charging C-rate based on the obtained SOC-resistance curve.

[0015] The control unit can be configured to set the maximum allowable SOC of the charging C-rate corresponding to the SOC-resistance curve to an upper limit SOC when a resistance corresponding to the upper limit SOC among a plurality of resistances corresponding to a target SOC section of the SOC-resistance curve is the largest.

[0016] The control unit can be configured to set the maximum allowable SOC of the charging C-rate corresponding to the SOC-resistance curve based on at least one maximum point when there is a resistance greater than a resistance corresponding to an upper limit SOC among a plurality of resistances corresponding to a target SOC section of the SOC-resistance curve and there is at least one maximum point in the target SOC section of the SOC-resistance curve.

[0017] The control unit can be configured to set a maximum allowable SOC of a charge C-rate corresponding to the SOC-resistance curve based on at least one inflection point when there is a resistance greater than a resistance corresponding to an upper limit SOC of a target SOC section among a plurality of resistances corresponding to the target SOC section, there is no maximum point in the target SOC section, and there is at least one inflection point in the target SOC section.

[0018] The control unit can be configured to determine a first resistance section based on the first resistance curve, and diagnose a state of the battery by comparing the first resistance section with the target resistance.

[0019] The control unit can be configured to determine a first resistance line with respect to a plurality of resistances included in the first resistance curve, and determine the first resistance section by adding a preset resistance threshold value to the determined first resistance line.

[0020] The control unit can be configured to diagnose the state of the battery as a normal state when the target resistance belongs to the first resistance section.

[0021] The control unit can be configured to diagnose the state of the battery as an abnormal state when the target resistance does not belong to the first resistance section.

[0022] The control unit can be configured to calculate a sub-voltage change amount between a voltage of the battery immediately after a start of charging and a voltage at a time at which charging has been performed for a preset time according to the charge curve, calculate a sub-resistance of the battery based on the calculated sub-voltage change amount, and diagnose the state of the battery based on the target resistance and the sub-resistance.

[0023] The control unit can be configured to determine a second resistance section based on a second resistance curve in which sub-resistances of the battery calculated in each previous charge cycle are stored, and diagnose the state of the battery based on a result of comparing the first resistance section with the target resistance and a result of comparing the second resistance section with the sub-resistance.

[0024] The control unit can be configured to determine a second resistance line with respect to a plurality of resistances included in the second resistance curve, and determine the second resistance section by adding a preset resistance threshold value to the determined second resistance line.

[0025] The control unit can be configured to diagnose the state of the battery as a normal state when the target resistance belongs to the first resistance section or the sub-resistance belongs to the second resistance section.

[0026] The control unit can be configured to diagnose the state of the battery as an abnormal state when the target resistance does not belong to the first resistance section and the sub-resistance does not belong to the second resistance section.

[0027] The control unit can be configured to calculate the voltage variation amount by calculating a difference between an initial voltage of the battery immediately before the start of charging and a voltage of the battery immediately after the start of charging.

[0028] The control unit can be configured to calculate an initial resistance based on the voltage variation amount and a charging current of the charging process, compare an initial SOC of the battery immediately before the start of charging with a preset target SOC, and calculate a target resistance based on the initial resistance according to a comparison result.

[0029] The control unit can be configured to determine the initial resistance as the target resistance when the initial SOC is equal to the target SOC.

[0030] The control unit can be configured to calculate the target resistance according to the initial resistance based on a resistance table preset to represent a resistance ratio for each SOC when the initial SOC is different from the target SOC.

[0031] The control unit can be configured to calculate a total resistance of the battery by dividing the initial resistance by a resistance ratio corresponding to the initial SOC in the resistance table, and calculate a target resistance of the battery by multiplying the total resistance by a resistance ratio corresponding to the target SOC in the resistance table.

[0032] A battery pack according to another aspect of the present disclosure can include the apparatus for diagnosing a battery according to one aspect of the present disclosure.

[0033] A method for diagnosing a battery according to still another aspect of the present disclosure can include a curve obtaining step of obtaining a charging curve representing a voltage variation of the battery in a charging process according to a charging protocol in which a correspondence between a charging C-rate and a maximum allowable SOC is preset, a voltage variation amount calculating step of calculating a voltage variation amount of the battery at a charging start point of the charging curve, a target resistance calculating step of calculating a target resistance of the battery based on the calculated voltage variation amount, and a diagnosing step of diagnosing a state of the battery by comparing the target resistance with a first resistance curve in which target resistances of the battery calculated in each previous charging cycle are stored.

[0034] The method for diagnosing a battery according to still another aspect of the present disclosure can further include a charging protocol changing step of changing the charging protocol when the state of the battery is diagnosed as an abnormal state in the diagnosing step.

[0035] Advantageous Effects

[0036] According to one aspect of the present disclosure, the apparatus for diagnosing a battery can non-destructively diagnose a state of the battery based on a resistance behavior of the battery. Specifically, the apparatus for diagnosing a battery can predict in advance whether the battery is likely to experience a sudden failure based on a resistance of the battery.

[0037] Further, according to one aspect of the disclosure, if the state of the battery is diagnosed as an abnormal state, the state of the battery can be prevented from deteriorating due to charging by changing a charging protocol.

[0038] Effects of the disclosure are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. BRIEF DESCRIPTION OF DRAWINGS

[0039] The accompanying drawings illustrate preferred embodiments of the disclosure and together with the foregoing disclosure, provide further understanding of the technical features of the disclosure, and therefore, the disclosure is not construed as being limited to the drawings.

[0040] Figure 1 FIG. 1 is a diagram schematically illustrating an apparatus for diagnosing a battery according to one embodiment of the disclosure.

[0041] Figure 2 FIG. 2 is a diagram schematically illustrating a charging profile according to one embodiment of the disclosure.

[0042] Figure 3 FIG. 3 is a diagram schematically illustrating a first resistance profile according to one embodiment of the disclosure. Figure 2

[0043] Figure 4 FIG. 4 is a diagram schematically illustrating a second resistance profile according to one embodiment of the disclosure.

[0044] Figure 5 FIG. 5 is a diagram schematically illustrating a battery profile according to one embodiment of the disclosure. Figure 4

[0045] FIG. 6 is a diagram schematically illustrating a capacity retention rate of a battery according to one embodiment of the disclosure. Figure 6

[0046] Figure 7 FIG. 7 is a diagram schematically illustrating a resistance table according to one embodiment of the disclosure.

[0047] Figure 8 FIG. 8 is a diagram schematically illustrating a second resistance profile according to one embodiment of the disclosure.

[0048] Figure 9 FIG. 9 is a diagram schematically illustrating a second resistance profile according to one embodiment of the disclosure. Figure 8

[0049] Figure 10 FIG. 10 is a diagram schematically illustrating a battery profile according to one embodiment of the disclosure.

[0050] Figure 11 FIG. 11 is a diagram schematically illustrating a portion of a battery profile according to one embodiment of the disclosure. Figure 10

[0051] FIG. 12 is a diagram schematically illustrating a portion of a battery profile according to one embodiment of the disclosure.​​​Figures 12 to 14 This is a schematic diagram illustrating a SOC-resistance curve according to an embodiment of the present disclosure.

[0052] Figure 15 This is a graph comparing the first resistance curves of the first and second batteries.

[0053] Figure 16 This is a graph comparing the second resistance curves of the first and second batteries.

[0054] Figure 17 This is a graph comparing the cycle-by-cycle capacity retention of the first and second batteries.

[0055] Figure 18 This is a graph comparing the rate of increase in resistance per cycle for the first and second cells.

[0056] Figure 19 This is a schematic diagram illustrating a battery pack according to another embodiment of the present disclosure.

[0057] Figure 20 This is a schematic diagram illustrating a vehicle according to yet another embodiment of the present disclosure.

[0058] Figure 21 and Figure 22 This is a schematic diagram illustrating a method for diagnosing a battery according to yet another embodiment of the present disclosure. Detailed Implementation

[0059] 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 rather as being 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.

[0060] Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of this disclosure. It should be understood that other equivalents and modifications may be made thereto without departing from the scope of this disclosure.

[0061] In addition, in describing this disclosure, a detailed description of a known element or function is omitted here when it is considered to obscure the key subject matter of the disclosure.

[0062] 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 these elements by terminology.

[0063] Throughout this specification, when a section is referred to as “comprising” or “including” any element, it means that the section may further include other elements without excluding them, unless otherwise specifically stated.

[0064] Also, throughout the specification, when a part is referred to as being "connected" to another part, it is not limited to the case where they are "directly connected", but also includes the case where another element is interposed therebetween.

[0065] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0066] Figure 1 FIG. 1 is a diagram schematically illustrating an apparatus for diagnosing a battery according to one embodiment of the present disclosure.

[0067] Referring to Figure 1 , the apparatus for diagnosing a battery can include a curve obtaining unit and a control unit.

[0068] Here, the battery refers to an independent single body having a negative terminal and a positive terminal and being physically separable. As an example, a lithium ion battery or a lithium polymer battery can be considered as the battery. Also, the type of the battery can be cylindrical, prismatic, or pouch. In addition, the battery can mean a battery bank, a battery module, or a battery pack in which a plurality of single bodies are connected in series and / or in parallel. Hereinafter, for convenience of explanation, the battery will be explained to mean one independent single body.

[0069] The curve obtaining unit 110 can be configured to obtain a charge curve CP representing a voltage variation of the battery in a charging process according to a charging protocol in which a correspondence between a charging C rate and a maximum allowable SOC is preset.

[0070] Specifically, the charge curve CP can be a curve representing a voltage variation of the battery according to time or capacity from a charging start point to a charging end point in a charging process. For example, the charge curve CP can be a curve representing a correspondence between a charging time and a voltage. As another example, the charge curve CP can be a curve representing a correspondence between an SOC (State of Charge) and a voltage. As still another example, the charge curve CP can be a curve representing a correspondence between a capacity and a voltage.

[0071] Here, since the charging time, the capacity according to the charging time, and the SOC according to the charging time are mutually substitutable factors with respect to time, the charge curve CP is not particularly limited. However, for convenience of explanation, the charge curve CP will be described below as a curve representing a correspondence between an SOC and a voltage.

[0072] For example, the curve obtaining unit 110 can directly receive the charge curve CP of the battery from the outside. That is, the curve obtaining unit 110 can obtain the charge curve CP by being connected to the outside via a wire and / or wirelessly receiving the charge curve CP.

[0073] As another example, the curve acquisition unit 110 can receive battery information regarding the battery's voltage and SOC. Then, the curve acquisition unit 110 can generate a charging curve CP based on the received battery information. In other words, the curve acquisition unit 110 can obtain the charging curve CP by directly generating the charging curve CP based on the battery information.

[0074] Figure 2 This is a schematic diagram illustrating a charging curve CP according to one embodiment of the present disclosure. Figure 2 In one embodiment, the charging curve CP can be represented as an XY curve, where the X-axis is set to SOC and the Y-axis is set to voltage.

[0075] Specifically, Figure 2 An example is the charging curve CP of a fast-charging battery. For example, battery charging begins at SOC S1 (%) and fast charging ends at SOC S6 (%). Then, the battery is fast-charged while the charging rate C decreases at SOC S2 (%), S3 (%), S4 (%), and S5 (%). That is, the charging rate C in the SOC segment from S1 (%) to S2 (%) is greater than the charging rate C in the SOC segment from S2 (%) to S3 (%). The charging rate C in the SOC segment from S2 (%) to S3 (%) is greater than the charging rate C in the SOC segment from S3 (%) to S4 (%). The charging rate C in the SOC segment from S3 (%) to S4 (%) is greater than the charging rate C in the SOC segment from S4 (%) to S5 (%). The charging rate C in the SOC segment from S4 (%) to S5 (%) is greater than the charging rate C in the SOC segment from S5 (%) to S6 (%). In other words, the maximum permissible SOC that can be charged can be preset for each C rate.

[0076] The curve acquisition unit 110 can be connected to communicate with the control unit 120. For example, the curve acquisition unit 110 can be connected to the control unit 120 via wired and / or wireless means. The curve acquisition unit can send the acquired charging curve CP to the control unit 120.

[0077] The control unit 120 can be configured to calculate the voltage change of the battery at the start point of charging on the charging curve CP.

[0078] Specifically, the battery can be in an unloaded state immediately before charging begins. Therefore, the initial voltage of the battery immediately before charging begins is OCV (open circuit voltage).

[0079] Figure 3 It is shown Figure 2 A magnified view of the charging curve. For example, immediately before charging begins, the battery's SOC is S1 (%) and the voltage is V1 (V).

[0080] And, when the charging starts, the voltage of the battery rapidly increases compared to the initial voltage due to the internal resistance of the battery. For example, assume that the terminal voltage of the battery is V, the initial voltage is OCV, the charging current is I, and the internal resistance of the battery is R. Here, the terminal voltage of the battery can be expressed according to the formula "V = OCV + IR". That is, immediately after the charging starts, the voltage of the battery can increase "IR".

[0081] The control unit 120 can be configured to calculate the voltage variation amount by calculating a difference between the initial voltage of the battery immediately before the charging starts and the voltage of the battery immediately after the charging starts.

[0082] Specifically, the control unit 120 can calculate the voltage variation amount by calculating a difference between the OCV of the battery immediately before the charging starts and the terminal voltage of the battery immediately after the charging starts.

[0083] For example, in an embodiment of Figure 3 , the control unit 120 can calculate the voltage variation amount by calculating the formula "V2 - V1".

[0084] The control unit 120 can be configured to calculate the target resistance of the battery based on the calculated voltage variation amount.

[0085] The control unit 120 can be configured to calculate the target resistance based on the charging current and the voltage variation amount of the charging process.

[0086] Specifically, the control unit 120 can calculate the target resistance based on the voltage variation amount and the charging current using Ohm's law. For example, assume that the voltage variation amount is ΔV and the charging current is I. The control unit 120 can calculate the target resistance by calculating the formula "ΔV ÷ I".

[0087] For example, in an embodiment of Figure 2 and Figure 3 , assume that the charging current of the SOC section of S1 (%) to S2 (%) is I. The control unit 120 can calculate the target resistance as a value obtained by dividing the voltage variation amount (V2 - V1) by the charging current (I).

[0088] The control unit 120 can be configured to diagnose the state of the battery by comparing the target resistance with a first resistance curve P1 in which the target resistance of the battery calculated in each previous charging cycle is stored.

[0089] Specifically, the first resistance curve P1 is a curve in which a target resistance of the battery calculated for each previous charging cycle is stored. For example, assuming that a current cycle is an n-th cycle, target resistances calculated for first to (n-1)-th cycles can be stored in the first resistance curve P1. Then, when a battery state diagnosis for the n-th cycle is completed, a target resistance calculated for the n-th cycle can be stored in the first resistance curve P1.

[0090] Figure 4 FIG. 1 is a graph schematically illustrating a first resistance curve P1 according to an embodiment of the disclosure. In Figure 4 In an embodiment of FIG. 1, the first resistance curve P1 can be represented as an X-Y graph in which an X-axis is set as a cycle and a Y-axis is set as a resistance.

[0091] The control unit 120 can be configured to determine a first resistance section R1 based on the first resistance curve P1.

[0092] First, the control unit 120 can be configured to determine a first resistance line L1 for a plurality of resistances included in the first resistance curve P1.

[0093] For example, the control unit 120 can determine the first resistance line L1 for the first resistance curve P1 through regression analysis. Here, the first resistance line L1 can be linear or non-linear.

[0094] As another example, the control unit 120 can determine the first resistance line L1 by considering a preset first reference resistance line and a regression analysis result of the first resistance curve P1 together. Here, the first reference resistance line is a resistance line derived from a first resistance curve P1 of a reference battery that is designed in advance. That is, the reference battery is a battery designed in advance in a normal state, and the first reference resistance line is a resistance line that can be applied to a battery in a normal state. Accordingly, the control unit 120 can determine the first resistance line L1 corresponding to the first resistance curve P1 by combining the first reference resistance line onto the regression analysis result of the first resistance curve P1.

[0095] Preferably, the control unit 120 can determine the first resistance line L1 for the first resistance curve P1 through regression analysis.

[0096] Figure 5 FIG. 2 is an enlarged view illustrating Figure 4 the first resistance curve P1 of FIG. 1. In Figure 5 In an embodiment of FIG. 2, the control unit 120 can determine the first resistance line L1 of the first resistance curve P1.

[0097] The control unit 120 can be configured to determine the first resistance section R1 by adding a preset resistance threshold to the determined first resistance line L1.

[0098] Specifically, the control unit 120 can adjust the first resistance line L1 by adding a preset resistance threshold value to the resistance value per cycle according to the first resistance line L1. In addition, the control unit 120 can determine a resistance section equal to or less than the adjusted first resistance line L1 as the first resistance section R1.

[0099] For example, in an embodiment of the present disclosure, Figure 5 In an embodiment of the present disclosure, the control unit 120 can move the first resistance line L1 in parallel along the Y-axis by adding the resistance threshold value TH to the resistance value per cycle of the first resistance line L1. In addition, the control unit 120 can determine a resistance section equal to or less than the first resistance line L1 as the first resistance section R1.

[0100] In addition, the control unit 120 can be configured to diagnose the state of the battery by comparing the first resistance section R1 with the target resistance.

[0101] Specifically, the control unit 120 can diagnose the state of the battery depending on whether the target resistance belongs to the first resistance section R1.

[0102] First, if the resistance value of the target resistance is less than or equal to the resistance value of the first resistance line L1, the control unit 120 can determine that the target resistance belongs to the first resistance section R1. Conversely, if the resistance value of the target resistance exceeds the resistance value of the first resistance line L1, the control unit 120 can determine that the target resistance does not belong to the first resistance section R1.

[0103] For example, the control unit 120 can be configured to diagnose the state of the battery as a normal state if the target resistance belongs to the first resistance section R1.

[0104] As another example, the control unit 120 can be configured to diagnose the state of the battery as an abnormal state if the target resistance does not belong to the first resistance section R1.

[0105] Here, the normal state means a state in which sudden failure is less likely to occur. Also, the abnormal state means a state in which sudden failure is predicted to be highly likely to occur. In other words, the battery diagnosed to be in the abnormal state can be a battery in which sudden failure is highly likely to occur.

[0106] In general, when fast charging is frequently performed, lithium plating in which lithium metal is deposited on the surface of the negative electrode can occur more frequently than when normal charging is performed. In addition, because internal short-circuiting, fire, explosion, or sudden failure that can occur due to lithium plating can occur suddenly, it is important to identify warning symptoms in advance.

[0107] In particular, as by-products accumulate at the interface between the negative electrode and the separator, plugging the pores of the separator and depleting the electrolyte, the liquid diffusion resistance of lithium ions can significantly increase before sudden failure occurs. Since the increase in the target resistance is indicative of an increase in the liquid diffusion resistance, the control unit 120 can determine the possibility of sudden failure of the battery based on whether the target resistance belongs to the first resistance section R1.

[0108] For example, in an embodiment of the battery of FIG. 1, the target resistance of the battery does not belong to the first resistance section R1 from the start of the C1 cycle. Thus, the control unit 120 can diagnose the state of the battery as an abnormal state from the start of the C1 cycle. Figure 5

[0109] Figure 6 FIG. 2 is a graph schematically showing the capacity retention rate of a battery according to one embodiment of the disclosure. Specifically, referring to FIG. 2, the capacity retention rate of the battery is shown as a function of the number of cycles. Figure 6 In the CS cycle, sudden failure occurs in the battery, and the capacity retention rate sharply decreases to less than 75%. Since sudden failure occurs suddenly in this way, the device 100 for diagnosing a battery can predict and diagnose the possibility of sudden failure in advance based on the behavior of the target resistance.

[0110] Meanwhile, the control unit 120 included in the device 100 for diagnosing a battery can optionally include a processor, an application specific integrated circuit (ASIC), other chipsets, logic circuitry, registers, communication modems, data processing devices, and the like known in the art to perform various control logics performed in the disclosure. In addition, when the control logics are implemented as software, the control unit 120 can be implemented as a set of program modules. At this time, the program modules can be stored in a memory and executed by the control unit 120. The memory can be internal or external to the control unit 120, and can be connected to the control unit 120 by various well-known means.

[0111] In addition, the device 100 for diagnosing a battery can further include a storage unit 130. The storage unit 130 can store data and programs required for the operation and functions of each component of the device 100 for diagnosing a battery, data generated in the process of performing the operation or function, and the like. The kind of the storage unit 130 is not particularly limited as long as it is a known information storage device capable of recording, erasing, updating, and reading data. As an example, the information storage device can include a RAM, a flash memory, a ROM, an EEPROM, a register, and the like. In addition, the storage unit 130 can store program codes in which processes executable by the control unit 120 are defined.

[0112] ​For example, the storage unit 130 can store various information for diagnosing the state of the battery, such as the charge profile CP, the first resistance profile P1, the first resistance line L1, the resistance threshold TH, and the first resistance section R1.

[0113] Hereinafter, an embodiment in which the control unit 120 calculates the target resistance when the SOC of the charge start point of the battery is not constant for each cycle will be described.

[0114] The control unit 120 can be configured to calculate the initial resistance based on the voltage variation and the charge current of the charge process.

[0115] In addition, the control unit 120 can be configured to compare the initial SOC of the battery immediately before the start of charging with a preset target SOC.

[0116] Specifically, the target SOC can be preset to any one of the available SOC sections of the battery. For example, the target SOC can be preset to SOC 10%.

[0117] Depending on the situation in which the battery is used, the initial SOC of the battery immediately before the start of charging can vary. For example, in the nth cycle, the battery can be charged from 8% SOC, and in the nth+1 cycle, the battery can be charged from 15% SOC. Accordingly, in order to more accurately calculate the target resistance, the control unit 120 can compare the initial SOC of the battery in the current cycle with the target SOC.

[0118] The control unit 120 can be configured to calculate the target resistance based on the initial resistance according to the comparison result.

[0119] Specifically, the control unit 120 can calculate the target resistance in different ways when the initial SOC is the same as the target SOC and when the initial SOC is different from the target SOC.

[0120] First, if the initial SOC is equal to the target SOC, the control unit 120 can be configured to determine the initial resistance as the target resistance.

[0121] Specifically, the control unit 120 can be configured to calculate the voltage variation by calculating the difference between the initial voltage of the battery immediately before the start of charging and the voltage of the battery immediately after the start of charging. Then, the control unit 120 can calculate the initial resistance by dividing the calculated voltage variation by the charge current. Finally, the control unit 120 can determine the calculated initial resistance as the target resistance of the battery.

[0122] Next, if the initial SOC is different from the target SOC, the control unit 120 can be configured to calculate the target resistance according to the initial resistance based on the resistance table T preset to represent the resistance ratio of each SOC.

[0123] Specifically, the control unit 120 can convert the initial resistance corresponding to the initial SOC to the target resistance corresponding to the target SOC based on the preset resistance table T.

[0124] More specifically, the control unit 120 can be configured to determine the total resistance of the battery by dividing the initial resistance by the resistance ratio corresponding to the initial SOC in the resistance table T. In addition, the control unit 120 can be configured to calculate the target resistance of the battery by multiplying the calculated total resistance by the resistance ratio corresponding to the target SOC in the resistance table T.

[0125] Figure 7 FIG. 1 is a diagram schematically illustrating a resistance table T according to one embodiment of the present disclosure. In the embodiment of FIG. 1, the resistance table T is set at 5% SOC intervals, but the SOC intervals in the resistance table T can be applied without limitation. In addition, the resistance ratio of the SOC (e.g., 3%) not included in the resistance table T can be interpolated and utilized based on the resistance ratios (p1 and p5) of the adjacent SOCs (e.g., 0% and 5%). Figure 7 In the embodiment of FIG. 1, the sum of the resistance ratios p1 to p100 is 1 or 100%.

[0126] Meanwhile, in the embodiment of FIG. 1, the resistance table T is set at 5% SOC intervals, but the SOC intervals in the resistance table T can be applied without limitation. In addition, the resistance ratio of the SOC (e.g., 3%) not included in the resistance table T can be interpolated and utilized based on the resistance ratios (p1 and p5) of the adjacent SOCs (e.g., 0% and 5%). Figure 7 In the embodiment of FIG. 1, the sum of the resistance ratios p1 to p100 is 1 or 100%.

[0127] In the embodiment of FIG. 1, it is assumed that the preset target SOC is 10%, the initial SOC of the battery is k%, and the initial resistance is R. The control unit 120 can calculate the total resistance of the battery by dividing the initial resistance R by the resistance ratio pk of the initial SOC. For example, the control unit 120 can calculate the total resistance of the battery by the calculation formula "R ÷ pk". In addition, the control unit 120 can determine the target resistance of the battery by multiplying the total resistance of the battery by the resistance ratio p10 of the target SOC. For example, the control unit 120 can calculate the target resistance of the battery by the calculation formula "R ÷ pk × p10". Figure 7 That is, the control unit 120 can convert the initial resistance "R" corresponding to the initial SOC k (%) to the target resistance "R ÷ pk × p10" corresponding to the target SOC 10 (%). Then, the control unit 120 can diagnose the state of the battery based on the result of comparing the target resistance with the first resistance section R1.

[0128]

[0129] ​The apparatus 100 for diagnosing a battery according to one embodiment of the disclosure can determine a target resistance by considering a case in which an initial SOC of the battery is not constant, and diagnose a state of the battery according to the determined target resistance. That is, the apparatus 100 for diagnosing a battery has an advantage in that it can diagnose a state of the battery even in a case in which an initial SOC of the battery is not constant for each cycle by determining a target resistance using the resistance meter T.

[0130] Hereinafter, an embodiment in which the control unit 120 additionally diagnoses a state of the battery by further considering a sub-resistance is described.

[0131] The control unit 120 can be configured to calculate a sub-voltage change amount between a voltage of the battery immediately after a start of charging and a voltage at a point of time at which charging has been performed for a preset time according to the charge profile CP.

[0132] Specifically, the preset time can be determined within a time in which charging at the same charge C-rate is performed from a charging start point. For example, the preset time can be 30 seconds.

[0133] For example, in the embodiment of Figure 3 , an initial voltage of the battery immediately before the start of charging is V1, a voltage of the battery immediately after the start of charging is V2, and a voltage of the battery at the point of time at which charging has been performed for the preset time is V3. The control unit 120 can calculate a sub-voltage change amount of the battery by a calculation formula "V3-V2".

[0134] The control unit 120 can be configured to calculate a sub-resistance of the battery based on the calculated sub-voltage change amount.

[0135] For example, in the embodiments of Figure 2 and Figure 3 , it is assumed that a charge current of the SOC section of S1 (%) to S2 (%) is I. The control unit 120 can calculate a sub-resistance as a value obtained by dividing the sub-voltage change amount (V3-V2) by the charge current (I).

[0136] The control unit 120 can be configured to diagnose a state of the battery based on the target resistance and the sub-resistance.

[0137] The control unit 120 can be configured to determine a second resistance section R2 based on a second resistance profile P2 in which sub-resistances of the battery calculated in each previous charge cycle are stored.

[0138] Specifically, the second resistance curve P2 is a curve in which a sub-resistance of the battery calculated for each past charge cycle is stored. For example, assuming that the current cycle is the nth cycle, the sub-resistance calculated for the first to (n-1)th cycles can be stored in the second resistance curve P2. Then, when the battery state diagnosis for the nth cycle is completed, the sub-resistance calculated for the nth cycle can be stored in the second resistance curve P2.

[0139] Figure 8 FIG. 2 is a graph schematically illustrating a second resistance curve P2 according to an embodiment of the disclosure. In Figure 8 In an embodiment of FIG. 2, the second resistance curve P2 can be represented as an X-Y graph in which an X-axis is set as a cycle and a Y-axis is set as a resistance.

[0140] The control unit 120 can be configured to determine a second resistance line L2 for a plurality of resistances included in the second resistance curve P2.

[0141] For example, the control unit 120 can determine the second resistance line L2 of the second resistance curve P2 through regression analysis. Here, the second resistance line L2 can be linear or non-linear.

[0142] As another example, the control unit 120 can determine the second resistance line L2 by considering a preset second reference resistance line and a regression analysis result of the second resistance curve P2 together. Here, the second reference resistance line is a resistance line derived from a second resistance curve P2 of a reference battery that is designed in advance. That is, the reference battery is a battery that is designed in advance in a normal state, and the second reference resistance line is a resistance line that can be applied to a battery in a normal state. Accordingly, the control unit 120 can determine the second resistance line L2 corresponding to the second resistance curve P2 by combining the second reference resistance line to the regression analysis result of the second resistance curve P2.

[0143] Preferably, the control unit 120 can determine the second resistance line L2 for the second resistance curve P2 through regression analysis.

[0144] Figure 9 FIG. 3 is an enlarged view illustrating Figure 8 the second resistance curve P2 of FIG. 2. In Figure 9 In an embodiment of FIG. 3, the control unit 120 can determine the second resistance line L2 of the second resistance curve P2.

[0145] The control unit 120 can be configured to determine the second resistance section R2 by adding a preset resistance threshold to the determined second resistance line L2. Specifically, in the same manner as the first resistance section R1 is determined by adding a resistance threshold to the first resistance line L1, the control unit 120 can determine the second resistance section R2 by adding a resistance threshold to the second resistance line L2. Here, the resistance threshold added to the first resistance line L1 and the resistance threshold added to the second resistance line L2 can be the same as or different from each other.

[0146] For example, in an embodiment of the present disclosure, Figure 9 The control unit 120 can move the second resistance line L2 parallel to the Y-axis by adding the resistance threshold TH to the resistance value of the second resistance line L2 per cycle. Also, the control unit 120 can determine a resistance section equal to or smaller than the second resistance line L2 as the second resistance section R2.

[0147] Also, the control unit 120 can be configured to diagnose the state of the battery based on a result of comparing the first resistance section R1 with the target resistance and a result of comparing the second resistance section R2 with the sub-resistance.

[0148] Specifically, the control unit 120 can diagnose the state of the battery based on whether the target resistance belongs to the first resistance section R1 and whether the sub-resistance belongs to the second resistance section R2.

[0149] First, if the resistance value of the target resistance is less than or equal to the resistance value of the first resistance line L1, the control unit 120 can determine that the target resistance belongs to the first resistance section R1. Conversely, if the resistance value of the target resistance exceeds the resistance value of the first resistance line L1, the control unit 120 can determine that the target resistance does not belong to the first resistance section R1.

[0150] Next, if the resistance value of the sub-resistance is less than or equal to the resistance value of the second resistance line L2, the control unit 120 can determine that the sub-resistance belongs to the second resistance section R2. Conversely, if the resistance value of the sub-resistance exceeds the resistance value of the second resistance line L2, the control unit 120 can determine that the sub-resistance does not belong to the second resistance section R2.

[0151] For example, the control unit 120 can be configured to diagnose the state of the battery as a normal state when the target resistance belongs to the first resistance section R1 or when the sub-resistance belongs to the second resistance section R2.

[0152] As another example, the control unit 120 can be configured to diagnose the state of the battery as an abnormal state if the target resistance does not belong to the first resistance section R1 and the sub-resistance does not belong to the second resistance section R2.

[0153] That is, the control unit 120 can diagnose the state of the battery as the abnormal state only when the target resistance does not belong to the first resistance section R1 and the sub-resistance does not belong to the second resistance section R2.

[0154] For example, in the embodiment of FIG. 10, Figure 5 , Figure 6 and Figure 9 , the target resistance in the C1 cycle does not belong to the first resistance section R1, but the sub-resistance belongs to the second resistance section R2. That is, if only the target resistance is considered, the state of the battery in the C1 cycle is diagnosed as the abnormal state, but if both the target resistance and the sub-resistance are considered, the state of the battery in the C1 cycle is diagnosed as the normal state. Then, the target resistance in the C2 cycle does not belong to the first resistance section R1, and the sub-resistance does not belong to the second resistance section R2. That is, the state of the battery in the C2 cycle is diagnosed as the abnormal state. Then, in the CS cycle after the C2 cycle, a sudden failure occurs in the battery.

[0155] The possibility of the sudden failure of the battery can be diagnosed earlier when the target resistance is used than when the sub-resistance is used. For example, the first cycle (e.g., C1) in which the target resistance does not belong to the first resistance section R1 precedes the first cycle (e.g., C2) in which the sub-resistance does not belong to the second resistance section R2.

[0156] However, the sudden failure means a state in which the internal resistance of the battery rapidly increases and the battery cannot be charged or discharged, and thus, from a conservative and strict point of view, the state of the battery should be diagnosed as the abnormal state. If the state of the battery is diagnosed by considering only the target resistance, the state of the battery can be misdiagnosed, and since the state of the battery is diagnosed as the abnormal state before the sub-resistance is considered, the period in which the battery can be used can be shortened.

[0157] Therefore, the apparatus 100 for diagnosing a battery according to the embodiment of the disclosure can more accurately diagnose the state of the battery by considering the sub-resistance in addition to the target resistance. In addition, the apparatus 100 for diagnosing a battery can increase the expected life of the battery by considering both the target resistance and the sub-resistance.

[0158] Hereinafter, an embodiment in which a charging protocol is changed depending on the diagnosed state of the battery is described.

[0159] Specifically, the control unit 120 can be configured to change the charging protocol when the state of the battery is diagnosed as the abnormal state. That is, when the state of the battery is diagnosed as the normal state, the preset charging protocol can not be changed. On the contrary, when the state of the battery is diagnosed as the abnormal state, if the battery is charged using its original charging protocol, the state of the battery can become worse. Therefore, in this case, it is necessary to change (modify, correct) the charging protocol.

[0160] The control unit 120 can be configured to repeat the charging period and the rest period at each charging C-rate included in the charging protocol, and obtain an SOC-resistance curve representing a correspondence between an SOC (State of Charge) of the charged battery and a resistance of the rest period.

[0161] Here, the SOC-resistance curve is a curve representing a correspondence between an SOC of the battery and a resistance of the rest period when the battery is charged by repeating the charging period and the rest period at one charging C-rate.

[0162] Preferably, the control unit 120 can obtain an SOC-resistance protocol for each charging C-rate included in the charging protocol. For example, if the charging protocol includes information on n charging C-rates, the control unit 120 can obtain n SOC-resistance protocols.

[0163] Figure 10 is a graph schematically showing a battery curve according to one embodiment of the disclosure. For example, in an embodiment of Figure 10 , a battery is charged by repeating a charging period and a rest period at a predetermined charging C-rate, and a correspondence between a charging time and a voltage can be represented as a battery curve. Since charging is temporarily suspended during the rest period, the voltage of the battery can drop.

[0164] Figure 11 is an enlarged view schematically showing a part of the battery curve of Figure 10 . The rest period can start at a voltage V r1 and end at a voltage V r2 . The rest period can start at a time t r1 and end at a time t r2 . That is, a voltage drop of AV rest may occur during a time interval At rest . Considering Ohm's law, a resistance of the rest period can be calculated based on an amount of voltage drop (AV rest ) corresponding to the charging C-rate and a charging current. Through this process, an SOC-resistance curve representing a correspondence between an SOC and a resistance is generated, and the control unit 120 can obtain the generated SOC-resistance curve.

[0165] As another example, the control unit 120 can obtain a battery curve (e.g., Figure 10 ) and calculate an SOC and a resistance at each rest period. In addition, the control unit 120 can directly generate an SOC-resistance curve representing a correspondence between an SOC and a resistance.

[0166] In the above-described embodiments, a voltage drop (AV rest ) in the rest period can be calculated based on a charging current and a voltage drop amount (AV rest ) corresponding to the charging C-rate.rest ) is described as a difference between a rest period start voltage (V r1 ) and a rest period end voltage (V r2 ). Here, the difference between the rest period start voltage (V r1 ) and the rest period end voltage (V r2 ) is a value including both an ohmic resistance and a charge transfer resistance of the battery. In some cases, the charge transfer resistance can more accurately represent the state of the battery than the ohmic resistance. In addition, the charge transfer resistance can be represented as a difference between a voltage (V r3 ) and the rest period end voltage (V r2 ). Here, the voltage (V r3 ) can be a voltage at a point at which a change in voltage over time is greater than a preset reference value. Thus, the voltage drop can be calculated based on the difference between the voltage (V r3 ) and the rest period end voltage (V r2 ), and the resistance can be calculated based on the calculated amount of voltage drop.

[0167] The control unit 120 can be configured to change the maximum allowable SOC corresponding to each charging C-rate based on the obtained SOC-resistance curve.

[0168] Figures 12 to 14 is a graph schematically illustrating an SOC-resistance curve according to one embodiment of the disclosure. Hereinafter, a target SOC section refers to a section in which the SOC of a BOL (beginning of life) battery is 50% or more. In other words, as the battery deteriorates or the charging C-rate increases, the ratio included in the target SOC section in the SOC-resistance curve can decrease.

[0169] For example, the control unit 120 can be configured to set the maximum allowable SOC of the charging C-rate corresponding to the SOC-resistance curve as the upper limit SOC when the resistance corresponding to the upper limit SOC of the target SOC section is the largest among the plurality of resistances corresponding to the target SOC section of the SOC-resistance curve.

[0170] Specifically, if the resistance corresponding to the upper limit SOC of the target SOC section is the largest, the maximum allowable SOC of the charging C-rate can be set as the upper limit SOC even if there is a maximum point and / or an inflection point in the target SOC section.

[0171] In the embodiment of Figure 12 , the first SOC-resistance curve S1 is a curve of a battery charged at an n1 C-rate. In the first SOC-resistance curve S1, P a is an upper limit of a target SOC section TR. Among the plurality of resistances belonging to the target SOC section TR, the resistance corresponding to P aThe corresponding resistance is the largest. Therefore, the maximum allowable SOC corresponding to the n1 C rate can be set to the SOC (SOC a The corresponding SOC (SOC a ).

[0172] As another example, the control unit 120 can be configured to set the maximum allowable SOC of the charging C rate corresponding to the SOC-resistance curve based on at least one maximum point if there is a resistance greater than the resistance corresponding to the upper limit SOC of the target SOC section among the plurality of resistances corresponding to the target SOC section and there is at least one maximum point in the target SOC section of the SOC-resistance curve.

[0173] Specifically, if the resistance corresponding to the upper limit SOC of the target SOC section is not the largest and there is a maximum point in the target SOC section, the maximum allowable SOC of the charging C rate can be set to the SOC of the maximum point even if there is an inflection point in the target SOC section.

[0174] Preferably, when the target SOC section includes a plurality of maximum points, the SOC of one of the plurality of maximum points can be set as the maximum allowable SOC. More preferably, the largest SOC among the SOCs corresponding to the plurality of maximum points can be set as the maximum allowable SOC.

[0175] In the embodiment of Figure 13 , the second SOC-resistance curve S2 is a curve of a battery charged at an n2 C rate. In the second SOC-resistance curve S2, P b is a maximum point of the target SOC section TR. Among the plurality of resistances belonging to the target SOC section TR, the resistance corresponding to P b is the largest. That is, among the plurality of resistances belonging to the target SOC section TR, the resistance corresponding to the upper limit of the target SOC section TR is not the largest. Therefore, the maximum allowable SOC corresponding to the n2 C rate can be set to the SOC (SOC b corresponding to P b .

[0176] As another example, the control unit 120 can be configured to set the maximum allowable SOC of the charging C rate corresponding to the SOC-resistance curve based on at least one inflection point if there is a resistance greater than the resistance corresponding to the upper limit SOC of the target SOC section among the plurality of resistances corresponding to the target SOC section, there is no maximum point in the target SOC section, and there is at least one inflection point in the target SOC section.

[0177] Specifically, even in the case where the inflection point exists in the target SOC section, only in the case where the resistance corresponding to the upper limit SOC among the plurality of resistances included in the target SOC section is not the largest and the maximum point does not exist in the target SOC section, the SOC corresponding to the inflection point can be set as the upper limit SOC which is the maximum allowable SOC of the charge C-rate. This is because the maximum allowable SOC must be conservatively and strictly set as the SOC indicating that lithium plating does not occur even if the battery is charged at the charge C-rate.

[0178] Preferably, when the target SOC section includes a plurality of inflection points, the SOC of one of the plurality of inflection points can be set as the maximum allowable SOC. More preferably, the maximum SOC among the SOCs corresponding to the plurality of inflection points can be set as the maximum allowable SOC.

[0179] In the embodiment of Figure 14 , the third SOC-resistance curve S3 is a curve of a battery charged at an n3 C-rate. In the third SOC-resistance curve S3, P c is an inflection point of the target SOC section TR. Among the plurality of resistances belonging to the target SOC section TR, the resistance corresponding to the upper limit SOC is not the largest, and the maximum point does not exist in the target SOC section TR. Therefore, the maximum allowable SOC corresponding to the n3 C-rate can be set as the SOC (SOC c ) corresponding to P c .

[0180] The apparatus 100 for diagnosing a battery according to the present disclosure can prevent the state of the battery from deteriorating due to subsequent charging by changing the charging protocol to correspond to the state of the diagnosed battery. In other words, the apparatus 100 for diagnosing a battery has the advantage of not only being able to diagnose the state of the battery but also being able to set a customized charging protocol for the battery that can increase the expected lifespan of the battery.

[0181] Hereinafter, the performance of a first battery (B a ) whose charging protocol is not changed and a second battery (B b ) whose charging protocol is changed by the apparatus 100 for diagnosing a battery is compared and explained. Here, the charging protocol of the second battery is changed (Bb) based on 100 cycles.

[0182] Figure 15 is a graph comparing the first resistance curve P1 of the first battery (B a ) and the second battery (B b ). The resistance of the first battery (B a ) whose charging protocol is not changed rapidly increases from about 120 cycles. On the other hand, the resistance of the second battery (B bincreases as the cycles progress, but the resistance does not increase as rapidly as the first battery (B a ).

[0183] Figure 16 is a graph comparing the second resistance profile P2 of the first battery (B a ) and the second battery (B b ). The resistance of the first battery (B a ) without a change in the charging protocol rapidly increases from about 140 cycles. On the other hand, the resistance of the second battery (B b ) increases as the cycles progress with a change in the charging protocol, but the resistance does not increase as rapidly as the first battery (B a ).

[0184] It can be confirmed that the resistance difference between the first battery (B a ) and the second battery (B b ) at 150 cycles is significantly different from the resistance difference between the first battery (B a ) and the second battery (B b ) at 100 cycles. That is, it can be confirmed that the state deterioration of the second battery (B b ) is prevented by changing the charging protocol.

[0185] Figure 17 is a graph comparing the capacity retention rate per cycle of the first battery (B a ) and the second battery (B b ). Figure 18 is a graph comparing the resistance increase rate (Ba) per cycle of the first battery (B a ) and the second battery (B b ).

[0186] Similar to the result of comparing the first battery (B a ) and the second battery (B b ) based on the first resistance profile P1 and the second resistance profile P2, the capacity retention rate and the resistance increase rate of the first battery (B a ) and the second battery (B b ) up to 100 cycles are almost similar. However, the capacity retention rate and the resistance increase rate of the first battery (B a ) and the second battery (B b ) at 150 cycles show a significant difference.

[0187] Depending on whether the charging protocol is changed, the capacity retention rate of the first battery (B a ) and the second battery (B b ) differs by about 5% after only 50 cycles (100 to 150 cycles), and the resistance increase rate differs by about 8%.

[0188] through the first battery (B a ) and the second battery (B b ), it can be confirmed that the lifespan of the battery can be increased when the battery is charged according to the charging protocol changed by the device 100 for diagnosing the battery.

[0189] The device 100 for diagnosing the battery according to the disclosure can be applied to a battery management system (BMS). That is, the BMS according to the disclosure can include the device 100 for diagnosing the battery described above. In this configuration, at least some of the components of the device 100 for diagnosing the battery can be implemented by supplementing or adding the functions of the components included in the conventional BMS. For example, the curve obtaining unit 110, the control unit 120, and the storage unit 130 of the device 100 for diagnosing the battery can be implemented as components of the BMS.

[0190] In addition, the device 100 for diagnosing the battery according to the disclosure can be provided in the battery pack 10. That is, the battery pack according to the disclosure can include the device 100 for diagnosing the battery described above and at least one battery cell. In addition, the battery pack can further include electrical components (relays, fuses, etc.) and a housing.

[0191] Figure 19 is a diagram illustrating a battery pack according to another embodiment of the disclosure.

[0192] The positive terminal of the battery 11 can be connected to the positive terminal P+ of the battery pack 10, and the negative terminal of the battery 11 can be connected to the negative terminal P- of the battery pack 10.

[0193] The measurement unit 12 can be connected to the first sensing line SL1, the second sensing line SL2, and the third sensing line SL3. Specifically, the measurement unit 12 can be connected to the positive terminal of the battery 11 through the first sensing line SL1, and connected to the negative terminal of the battery 11 through the second sensing line SL2. The measurement unit 12 can measure the voltage of the battery 11 based on the voltage measured at each of the first sensing line SL1 and the second sensing line SL2.

[0194] In addition, the measurement unit 12 can be connected to the current measurement unit A through the third sensing line SL3. For example, the current measurement unit A can be an ammeter or a shunt resistor capable of measuring the charging current and the discharging current of the battery 11. The measurement unit 12 can calculate the charging amount by measuring the charging current of the battery 11 through the third sensing line SL3. In addition, the measurement unit 12 can calculate the discharging amount by measuring the discharging current of the battery 11 through the third sensing line SL3.

[0195] For example, the curve obtaining unit 110 can receive battery information on the voltage and the current of the battery from the measurement unit 12. Then, the curve obtaining unit 110 can generate the charge curve CP based on the battery information.

[0196] As another example, the curve obtaining unit 110 can receive the charge curve CP from the measurement unit 12.

[0197] An external device can be connected to the positive terminal P+ and the negative terminal P- of the battery pack 10. For example, the external device can be a charging device or a load. In addition, the positive terminal of the battery 11, the positive terminal P+ of the battery pack 10, the external device, the negative terminal P- of the battery pack 10, and the negative terminal of the battery 11 can be electrically connected.

[0198] Figure 20 FIG. 1 is a diagram schematically illustrating a vehicle 1 according to still another embodiment of the disclosure.

[0199] Reference Figure 20 The battery pack 10 according to one embodiment of the disclosure can be included in a vehicle 1 such as an electric vehicle (EV) or a hybrid vehicle (HV). In addition, the battery pack 10 can drive the vehicle 1 by supplying electric power to a motor via an inverter provided in the vehicle 1. Here, the battery pack 10 can include the device 100 for diagnosing a battery. That is, the vehicle 1 can include the device 100 for diagnosing a battery. In this case, the device 100 for diagnosing a battery can be an on-vehicle device included in the vehicle 1.

[0200] Figure 21 and Figure 22 FIG. 1 is a diagram schematically illustrating a vehicle 1 according to still another embodiment of the disclosure.

[0201] Reference Figure 21 The method for diagnosing a battery can include a curve obtaining step (S100), a voltage variation amount calculating step (S200), a target resistance calculating step (S300), and a diagnosing step (S400).

[0202] Preferably, each step of the method for diagnosing a battery can be performed by the device 100 for diagnosing a battery. Hereinafter, overlapping contents with the previously described contents will be omitted or briefly described for convenience of explanation.

[0203] The curve obtaining step (S100) is a step of obtaining a charge curve CP representing a voltage variation of a battery during a charging process, and can be performed by the curve obtaining unit 110.

[0204] For example, the curve acquisition unit 110 can directly receive the battery charging curve CP from an external source. That is, the curve acquisition unit 110 can obtain the charging curve CP by being connected to an external source via a wired and / or wireless connection.

[0205] As another example, the curve acquisition unit 110 can receive battery information regarding the battery's voltage and SOC. Then, the curve acquisition unit 110 can generate a charging curve CP based on the received battery information. In other words, the curve acquisition unit 110 can obtain the charging curve CP by directly generating the charging curve CP based on the battery information.

[0206] The voltage change calculation step (S200) is a step that calculates the voltage change of the battery at the starting point of the charging curve CP, and can be executed by the control unit 120.

[0207] For example, the control unit 120 can be configured to calculate the voltage change by calculating the difference between the initial voltage of the battery immediately before charging begins and the voltage of the battery immediately after charging begins.

[0208] The target resistance calculation step (S300) is a step of calculating the target resistance of the battery based on the calculated voltage change, and can be executed by the control unit 120.

[0209] The control unit 120 can be configured to calculate the target resistance based on the voltage change and the charging current during the charging process.

[0210] For example, in Figure 2 and Figure 3 In this embodiment, it is assumed that the charging current of the SOC segment from S1 (%) to S2 (%) is I. The control unit 120 can calculate the target resistance as a value obtained by dividing the voltage change (V2-V1) by the charging current (I).

[0211] The diagnostic step (S400) is a step for diagnosing the state of the battery by comparing the target resistance with a first resistance curve P1, in which the target resistance of the battery calculated in each previous charging cycle is stored, and can be performed by the control unit 120.

[0212] The control unit 120 can be configured to determine the first resistance segment R1 based on the first resistance curve P1.

[0213] Further, the control unit 120 can be configured to diagnose the state of the battery by comparing the first resistance section R1 with the target resistance. For example, the control unit 120 can be configured to diagnose the state of the battery as a normal state if the target resistance belongs to the first resistance section R1. As another example, the control unit 120 can be configured to diagnose the state of the battery as an abnormal state if the target resistance does not belong to the first resistance section R1.

[0214] Reference Figure 22 The method for diagnosing a battery can further include a charging protocol changing step (S500).

[0215] The charging protocol changing step (S500) is a step for changing a charging protocol when the state of the battery is diagnosed as an abnormal state in the diagnosing step (S400), and can be performed by the control unit 120.

[0216] For example, the control unit 120 can be configured to set a maximum allowable SOC of a charging C-rate corresponding to the SOC-resistance curve as an upper limit SOC when a resistance corresponding to an upper limit SOC of a target SOC section among a plurality of resistances corresponding to the target SOC section of the SOC-resistance curve is the greatest.

[0217] As another example, the control unit 120 can be configured to set a maximum allowable SOC of a charging C-rate corresponding to the SOC-resistance curve based on at least one maximum point if there is a resistance greater than a resistance corresponding to an upper limit SOC of a target SOC section among a plurality of resistances corresponding to the target SOC section and there is at least one maximum point in the target SOC section of the SOC-resistance curve.

[0218] As still another example, the control unit 120 can be configured to set a maximum allowable SOC of a charging C-rate corresponding to the SOC-resistance curve based on at least one inflection point if there is a resistance greater than a resistance corresponding to an upper limit SOC of a target SOC section among a plurality of resistances corresponding to the target SOC section, there is no maximum point in the target SOC section, and there is at least one inflection point in the target SOC section.

[0219] The above-described embodiments of the disclosure can be realized not only by a device and a method but also by a program for implementing functions corresponding to configurations of the embodiments of the disclosure or a recording medium on which the program is recorded. The program or the recording medium can be easily realized by those skilled in the art from the above description of the embodiments.

[0220] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, since various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

[0221] In addition, those skilled in the art can make many substitutions, modifications, and changes to the present disclosure without departing from the technical aspects of the present disclosure, and the present disclosure is not limited to the above-described embodiments and drawings, and each embodiment can be selectively partially or wholly combined to allow various modifications.

[0222] (Explanation of reference numerals)

[0223] 1: vehicle

[0224] 10: battery pack

[0225] 11: battery

[0226] 12: measurement unit

[0227] 100: device for diagnosing battery

[0228] 110: curve obtaining unit

[0229] 120: control unit

[0230] 130: storage unit

Claims

1. A device for diagnosing a battery, comprising: A curve acquisition unit is configured to acquire a charging curve representing the voltage change of the battery during the charging process according to a charging protocol in which the correspondence between the charging rate C and the maximum permissible SOC is preset. as well as A control unit is configured to calculate the voltage change of the battery at the start point of the charging curve, calculate a target resistance of the battery based on the calculated voltage change, and diagnose the state of the battery by comparing the target resistance with a first resistance curve in which the target resistance of the battery calculated in each previous charging cycle is stored.

2. The device for diagnosing batteries according to claim 1, in, The control unit is configured to change the charging protocol when the state of the battery is diagnosed as abnormal.

3. The device for diagnosing batteries according to claim 1, in, The control unit is configured to obtain a SOC-resistance curve representing the correspondence between the SOC of a battery being charged simultaneously during repeated charging periods and rest periods at each charging C rate included in the charging protocol and the resistance during the rest period, and to change the maximum permissible SOC corresponding to each charging C rate based on the obtained SOC-resistance curve.

4. The device for diagnosing batteries according to claim 3, in, The control unit is configured to set the maximum allowable SOC of the charging C rate corresponding to the SOC-resistance curve to the upper limit SOC when the resistance corresponding to the upper limit SOC of the target SOC segment among a plurality of resistors corresponding to the target SOC segment of the SOC-resistance curve is the largest.

5. The device for diagnosing batteries according to claim 3, in, The control unit is configured to set the maximum allowable SOC of the charging C rate corresponding to the SOC-resistance curve based on the at least one maximum point when there is a resistor among a plurality of resistors corresponding to the target SOC segment of the SOC-resistance curve that is larger than the resistor corresponding to the upper limit SOC of the target SOC segment and there is at least one maximum point in the target SOC segment of the SOC-resistance curve.

6. The apparatus for diagnosing batteries according to claim 3, in, The control unit is configured to set the maximum allowable SOC for the charging C rate corresponding to the SOC-resistance curve based on the at least one inflection point when there is a resistor among a plurality of resistors corresponding to the target SOC segment of the SOC-resistance curve that is larger than the resistor corresponding to the upper limit SOC of the target SOC segment, there is no maximum point in the target SOC segment, and there is at least one inflection point in the target SOC segment.

7. The apparatus for diagnosing batteries according to claim 1, in, The control unit is configured to determine a first resistance segment based on the first resistance curve and to diagnose the state of the battery by comparing the first resistance segment with the target resistance.

8. The apparatus for diagnosing batteries according to claim 7, in, The control unit is configured to determine a first resistance line for a plurality of resistors included in the first resistance curve, and to determine the first resistance segment by adding a preset resistance threshold to the determined first resistance line.

9. The apparatus for diagnosing batteries according to claim 7, in, The control unit is configured to: When the target resistance belongs to the first resistance range, the state of the battery is diagnosed as normal, and When the target resistor does not belong to the first resistor segment, the state of the battery is diagnosed as an abnormal state.

10. The apparatus for diagnosing batteries according to claim 9, in, The control unit is configured to calculate, based on the charging curve, the sub-voltage change between the battery voltage immediately after charging begins and the voltage at a point where charging has been performed for a preset time, calculate the sub-resistance of the battery based on the calculated sub-voltage change, and diagnose the state of the battery based on the target resistance and the sub-resistance.

11. The apparatus for diagnosing batteries according to claim 10, in, The control unit is configured to determine a second resistance segment based on a second resistance curve in which sub-resistances of the battery calculated in each previous charging cycle are stored, and to diagnose the state of the battery based on the result of comparing the first resistance segment with the target resistance and the result of comparing the second resistance segment with the sub-resistance.

12. The apparatus for diagnosing batteries according to claim 11, in, The control unit is configured to determine a second resistance line for a plurality of resistors included in the second resistance curve, and to determine the second resistance segment by adding a preset resistance threshold to the determined second resistance line.

13. The apparatus for diagnosing batteries according to claim 11, in, The control unit is configured to: When the target resistor belongs to the first resistor segment or the sub-resistor belongs to the second resistor segment, the state of the battery is diagnosed as normal. and When the target resistor does not belong to the first resistor segment and the sub-resistor does not belong to the second resistor segment, the state of the battery is diagnosed as an abnormal state.

14. The apparatus for diagnosing batteries according to claim 1, The control unit is configured to calculate the voltage change by calculating the difference between the initial voltage of the battery immediately before charging begins and the voltage of the battery immediately after charging begins.

15. The apparatus for diagnosing batteries according to claim 14, in, The control unit is configured to calculate the initial resistance based on the voltage change and the charging current during the charging process, compare the initial SOC of the battery immediately before the start of charging with a preset target SOC, and calculate the target resistance based on the initial resistance according to the comparison result.

16. The apparatus for diagnosing batteries according to claim 15, The control unit is configured to: When the initial SOC equals the target SOC, the initial resistance is determined as the target resistance; and When the initial SOC differs from the target SOC, the target resistance is calculated based on the initial resistance using a resistor meter that is preset to represent the resistance ratio of each SOC.

17. The apparatus for diagnosing batteries according to claim 16, in, The control unit is configured to calculate the total resistance of the battery by dividing the initial resistance by the resistance ratio in the resistance table corresponding to the initial SOC, and to calculate the target resistance of the battery by multiplying the total resistance by the resistance ratio in the resistance table corresponding to the target SOC.

18. A battery pack comprising a device for diagnosing a battery according to any one of claims 1 to 17.

19. A method for diagnosing a battery, comprising: The curve acquisition step obtains a charging curve representing the voltage change of the battery during the charging process according to a charging protocol, in which the correspondence between the charging rate C and the maximum permissible SOC is preset. The voltage change calculation step calculates the voltage change of the battery at the charging start point of the charging curve. The target resistance calculation step calculates the target resistance of the battery based on the calculated voltage change. as well as The diagnostic step diagnoses the state of the battery by comparing the target resistance with a first resistance curve in which the target resistance of the battery calculated in each previous charging cycle is stored.

20. The method for diagnosing a battery according to claim 19, further comprising: A charging protocol change step, wherein the charging protocol change step changes the charging protocol when the state of the battery is diagnosed as abnormal during the diagnostic step.

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