Battery diagnosis device and battery diagnosis method using the same

Abstract

The present invention provides a battery diagnostic device capable of accurately measuring battery defects based on AC impedance data of the battery measured using electrochemical impedance spectroscopy, and a battery diagnostic method using the same. A battery diagnostic device according to one aspect of the present invention comprises: a diagnostic model configuring unit that configures a first Nyquist plot in which judgment points constituting the shape of a Nyquist plot are displayed using first AC impedance data, which is reference AC impedance data measured for a first battery that is a normal battery at different frequencies using electrochemical impedance spectroscopy; and a battery defect diagnostic unit configured to configure a second Nyquist plot in which measurement points constituting the shape of a Nyquist plot are displayed using second AC impedance data measured for a second battery that is a battery to be diagnosed as defective at different frequencies using electrochemical impedance spectroscopy, and to diagnose a defect in the second battery by comparing the first Nyquist plot and the second Nyquist plot.

Description

Technology Field

[0001] The present invention relates to a battery diagnostic device and a battery diagnostic method using the same, and more specifically, to a battery diagnostic device capable of accurately measuring battery defects using electrochemical impedance spectroscopy (EIS) and a battery diagnostic method using the same. Background Technology

[0002] Batteries, which have high applicability depending on the product family and electrical characteristics such as high energy density, are also called storage batteries or secondary batteries. They are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, not only for the primary advantage of being able to reduce the use of fossil fuels but also because no by-products are generated from the use of energy.

[0003] Therefore, batteries are widely applied in portable devices, electric vehicles (EVs) driven by electric power sources, and energy storage systems (ESS), and research and development on battery management systems (BMS), battery balancing circuits, and switching circuits are actively underway to manage batteries more efficiently.

[0004] Meanwhile, as these batteries become more high-performance and high-capacity, system malfunctions that lead to ignition or explosions can result in major disasters. Therefore, it is crucial not only to ensure safety and reliability during battery manufacturing but also to accurately diagnose defective batteries. The problem to be solved

[0005] The purpose of the present invention is to provide a battery diagnostic device capable of accurately measuring battery defects based on AC impedance data of the battery measured using electrochemical impedance spectroscopy, and a battery diagnostic method using the same.

[0006] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below. means of solving the problem

[0007] A battery diagnostic device according to one aspect of the present invention comprises: a diagnostic model constructing unit that constructs a first Nyquist plot with judgment points forming the shape of a Nyquist plot using first AC impedance data, which is reference AC impedance data measured for a first battery that is a normal battery at different frequencies using electrochemical impedance spectroscopy (EIS); and a battery defect diagnostic unit configured to construct a second Nyquist plot with measurement points forming the shape of a Nyquist plot using second AC impedance data measured for a second battery that is a battery to be diagnosed as defective at different frequencies using the electrochemical impedance spectroscopy, and to diagnose a defect in the second battery by comparing the first Nyquist plot with the second Nyquist plot.

[0008] Preferably, the diagnostic model component may be configured to display the judgment points on the first Nyquist plot as the starting point of the semicircle of the first Nyquist plot, the ending point of the semicircle of the first Nyquist plot, the point where the negative value of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot, the first measurement point of the first AC impedance data, and the last measurement point of the first AC impedance data.

[0009] Preferably, the battery failure diagnosis unit may include a measurement data configuration unit configured to form the second Nyquist plot and a measurement data reliability verification unit configured to determine the similarity of the graph trends of the first Nyquist plot and the second Nyquist plot.

[0010] Preferably, the measurement data configuration unit may be configured to display the measurement points on the second Nyquist plot as the starting point of the semicircle of the second Nyquist plot, the ending point of the semicircle of the second Nyquist plot, the point where the negative value of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot, the first measurement point of the second AC impedance data, and the last measurement point of the second AC impedance data.

[0011] Preferably, the measurement data reliability verification unit may be configured to perform at least one of the following: verifying whether the imaginary component of the second AC impedance data continuously decreases between the starting point of the semicircle of the second Nyquist plot and the point where the negative value of the imaginary component of the second AC impedance data is maximum on the semicircle of the second Nyquist plot on the second Nyquist plot; verifying whether the imaginary component of the second AC impedance data continuously increases between the point where the negative value of the imaginary component of the second AC impedance data is maximum on the semicircle of the second Nyquist plot on the second Nyquist plot and the end point of the semicircle of the second Nyquist plot on between the end point of the semicircle of the second Nyquist plot

[0012] Preferably, the battery defect diagnosis unit may further include a primary defect diagnosis unit configured to primarily diagnose a defect in the second battery by performing at least one of a comparison between the first measurement point of the first AC impedance data on the first Nyquist plot and the first measurement point of the second AC impedance data on the second Nyquist plot, and a comparison between the last measurement point of the first AC impedance data on the first Nyquist plot and the last measurement point of the second AC impedance data on the second Nyquist plot.

[0013] Preferably, the battery defect diagnosis unit may further include a secondary defect diagnosis unit configured to secondarily diagnose a defect in the second battery by performing at least one of the following: a comparison between the starting point of the semicircle of the first Nyquist plot and the starting point of the semicircle of the second Nyquist plot; a comparison between the ending point of the semicircle of the first Nyquist plot and the ending point of the semicircle of the second Nyquist plot; and a comparison between the point in the semicircle of the first Nyquist plot where the negative value of the imaginary component of the first AC impedance data is maximum and the point in the semicircle of the second Nyquist plot where the negative value of the imaginary component of the second AC impedance data is maximum.

[0014] Preferably, the secondary defect diagnosis unit may further include a raw data diagnosis unit configured to secondarily diagnose the defect of the second battery based on at least one of the starting point of the semicircle of the first Nyquist plot, the ending point of the semicircle of the first Nyquist plot, and the point where the negative value of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot, and an equivalent circuit model diagnosis unit configured to secondarily diagnose the defect of the second battery by comparing a judgment parameter value derived by constructing an equivalent circuit model based on the first Nyquist plot with a measurement parameter value derived by constructing an equivalent circuit model based on the second Nyquist plot.

[0015] A battery diagnosis method according to one aspect of the present invention comprises the steps of: constructing a first Nyquist plot in which judgment points constituting the shape of a Nyquist plot are displayed using first AC impedance data, which is reference AC impedance data measured for a first battery that is a normal battery at different frequencies using electrochemical impedance spectroscopy; constructing a second Nyquist plot in which measurement points constituting the shape of a Nyquist plot are displayed using second AC impedance data measured for a second battery that is a battery to be diagnosed as defective at different frequencies using electrochemical impedance spectroscopy; and diagnosing a defect in the second battery by comparing the first Nyquist plot with the second Nyquist plot. Effects of the invention

[0016] According to the battery diagnostic device of the present invention, the defect of the second battery can be accurately measured through precise diagnosis based on a plurality of comparison methods for a first Nyquist plot in which judgment points constituting the shape of the Nyquist plot are displayed using first AC impedance data measured for a first battery which is a normal battery, and a second Nyquist plot in which measurement points constituting the shape of the Nyquist plot are displayed using second AC impedance data measured for a second battery which is a battery subject to defect diagnosis.

[0017] In addition, various other additional effects may be achieved by various embodiments of the present invention. These various effects of the present invention are described in detail in each embodiment, or the description of effects that are easily understood by those skilled in the art is omitted. Brief explanation of the drawing

[0018] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a drawing showing a battery diagnostic device according to one embodiment of the present invention. FIG. 2 is a diagram exemplarily showing a first Nyquist plot configured by a diagnostic model configuration unit equipped in the battery diagnostic device of FIG. 1. Figure 3 is a diagram illustrating the types of judgment points that constitute the shape of the first Nyquist plot. FIG. 4 is a diagram exemplarily illustrating the determination of similarity between the graph trends of a first Nyquist plot and a second Nyquist plot by the measurement data reliability verification unit of the battery defect diagnosis unit equipped in the battery diagnosis device of FIG. 1. FIG. 5 is a diagram exemplarily illustrating the diagnosis of battery defect types using a Nyquist plot by the primary defect diagnosis unit and the secondary defect diagnosis unit of the battery defect diagnosis unit equipped in the battery diagnosis device of FIG. 1. FIG. 6 is a diagram exemplarily showing the raw values ​​of judgment points on a first Nyquist plot for battery failure diagnosis by the first failure diagnosis unit of the battery failure diagnosis unit equipped in the battery diagnosis device of FIG. 1 and battery failure diagnosis by the raw data diagnosis unit in the second failure diagnosis unit. FIG. 7 is a diagram exemplarily showing the judgment parameter values ​​derived by constructing an equivalent circuit model based on a first Nyquist plot for diagnosing battery defects in the equivalent circuit model diagnosis unit of the secondary defect diagnosis unit of the battery defect diagnosis unit equipped in the battery diagnosis device of FIG. 1. Figure 8 is a diagram exemplarily showing an equivalent circuit model constructed by the equivalent circuit model diagnostic unit. FIG. 9 is a diagram exemplarily showing the battery defect judgment conditions and battery diagnosis results by the first defect diagnosis unit and the second defect diagnosis unit. FIG. 10 is a flowchart illustrating a battery diagnostic method according to one embodiment of the present invention. Specific details for implementing the invention

[0019] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the present invention, and the present invention is defined only by the scope of the claims.

[0020] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0021] Throughout the specification, the same reference numerals refer to the same components, and "and / or" includes each of the mentioned components and all combinations of one or more thereof. Although terms such as "first," "second," etc., are used to describe various components, they are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the scope of the technical concept of the present invention.

[0022] Unless otherwise defined, all terms used herein (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0023] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0024] In describing the present invention, "battery" may be a capacitor or a secondary battery that stores power by charging. The battery may include at least one of a battery pack composed of a plurality of battery modules, at least one battery module within the battery pack, a battery module composed of a plurality of battery cells, at least one battery cell within the battery module, a representative module representing the plurality of battery modules, and a representative cell representing the plurality of battery cells.

[0025] FIG. 1 is a drawing showing a battery diagnostic device (10) according to an embodiment of the present invention, FIG. 2 is a drawing exemplarily showing a first Nyquist plot configured by a diagnostic model configuration part (100) provided in the battery diagnostic device (10) of FIG. 1, and FIG. 3 is a drawing exemplarily showing the types of judgment points that constitute the shape of the first Nyquist plot.

[0026] Referring to FIGS. 1 to 3, a battery diagnostic device (10) according to one embodiment of the present invention may include a diagnostic model configuration part (100) and a battery defect diagnosis part (200).

[0027] The above diagnostic model configuration unit (100) can construct a first Nyquist plot in which judgment points constituting the shape of the Nyquist plot are displayed using first AC impedance data, which is reference AC impedance data measured for a first battery that is a normal battery at different frequencies using electrochemical impedance spectroscopy (EIS). At this time, the Nyquist plot may partially include a semicircular shape.

[0028] For example, the diagnostic model configuration unit (100) may apply an input signal while modulating the frequency to the first battery to measure the output signal, and calculate a reference AC impedance according to frequency from the input signal and the output signal. For example, the frequency modulation range of the input signal may be from 0.1 Hz to 4000 Hz.

[0029] Additionally, the diagnostic model configuration unit (100) can separate the measured first AC impedance data by frequency. Furthermore, the diagnostic model configuration unit (100) can obtain the real component (Zre) and the imaginary component (Zimg) of the first AC impedance data and configure them into a first Nyquist plot. . At this time, the real component of the first AC impedance data represents the resistance value of the first AC impedance data and can form the horizontal axis of the first Nyquist plot. Additionally, the imaginary component of the first AC impedance data represents at least one of the inductance value or the capacitance value of the first AC impedance data, and the negative value (-Zimg) of the imaginary component of the first AC impedance data can form the vertical axis of the first Nyquist plot.

[0030] Specifically, the diagnostic model configuration unit (100) may be configured to display the judgment points on the first Nyquist plot as shown in FIGS. 2 and 3 as the semicircle start point (ZO) of the first Nyquist plot, the semicircle end point (Zmin) of the first Nyquist plot, the point (Zmax) where the negative value (-Zimg) of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot, the first measurement point (Zstart) of the first AC impedance data, and the last measurement point (Zend) of the first AC impedance data.

[0031] At this time, the starting point (ZO) of the first Nyquist plot can be set by deriving the point where the imaginary component (Zimg) of the first AC impedance data is zero through interpolation based on the frequency at which the sign of the imaginary component (Zimg) of the first AC impedance data changes and the frequency immediately before the sign of the imaginary component (Zimg) of the first AC impedance data changes.

[0032] In addition, the point (Zmax) where the negative value (-Zimg) of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot can be set by deriving the point where the imaginary component (Zimg) of the first AC impedance data decreases and then begins to increase in the frequency range after the starting point (ZO) of the semicircle of the first Nyquist plot.

[0033] In addition, the end point (Zmin) of the first Nyquist plot semicircle can be set by deriving the point where the imaginary component (Zimg) of the first AC impedance data increases and then begins to decrease in the frequency range after the point (Zmax) where the negative value (-Zimg) of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot.

[0034] Constructing the first Nyquist plot with a focus on the judgment points that constitute the shape of the Nyquist plot in this way is intended to precisely verify the defect of the battery by comparing it with the Nyquist plot derived from the battery subject to defect diagnosis with a focus on the said judgment points.

[0035] The battery defect diagnosis unit (200) above can construct a second Nyquist plot in which measurement points constituting the shape of a Nyquist plot are displayed using second AC impedance data measured for a second battery, which is a battery to be diagnosed for defects, at different frequencies using electrochemical impedance spectroscopy. As an example, the second battery, which is a battery to be diagnosed for defects, may have the same specifications as the first battery, which is a normal battery.

[0036] As an example, the battery defect diagnosis unit (200) may apply an input signal while modulating the frequency to the second battery to measure the output signal, and calculate a second AC impedance according to frequency from the input signal and the output signal. For example, the frequency modulation range of the input signal may be from 0.1 Hz to 4000 Hz.

[0037] Additionally, the battery defect diagnosis unit (200) can separate the measured second AC impedance data by frequency. Furthermore, the battery defect diagnosis unit (200) can obtain the real component (Zre) and the imaginary component (Zimg) of the second AC impedance data and construct them into a second Nyquist plot. At this time, the real component of the second AC impedance data represents the resistance value of the second AC impedance data and can form the horizontal axis of the second Nyquist plot. Additionally, the imaginary component of the second AC impedance data represents at least one of the inductance value or the capacitance value of the second AC impedance data, and the negative value (-Zimg) of the imaginary component of the second AC impedance data can form the vertical axis of the second Nyquist plot.

[0038] Here, the configuration of the second Nyquist plot can be performed by the measurement data configuration unit (210) of the battery failure diagnosis unit (200).

[0039] And, the measurement data configuration unit (210) may be configured to display the measurement points on the second Nyquist plot as the semicircle starting point (Z0) of the second Nyquist plot, the semicircle ending point (Zmin) of the second Nyquist plot, the point where the negative value (-Zimg) of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot (Zmax), the first measurement point (Zstart) of the second AC impedance data, and the last measurement point (Zend) of the second AC impedance data, similar to the judgment point configuration described above.

[0040] And, the battery defect diagnosis unit (200) may be configured to diagnose a defect in the second battery by comparing the first Nyquist plot and the second Nyquist plot.

[0041] That is, the battery defect diagnosis unit (200) can be configured to diagnose defects in the second battery through the graph increase / decrease trend of the first Nyquist plot and the second Nyquist plot, comparison of the overall shape, etc.

[0042] Meanwhile, the detailed configuration of the battery defect diagnosis unit (200) diagnosing the defect of the second battery, which is the battery subject to defect diagnosis, will be examined in detail in the related description that follows.

[0043] FIG. 4 is a diagram exemplarily illustrating the determination of similarity in graph trends between a first Nyquist plot and a second Nyquist plot by the measurement data reliability verification unit (220) of the battery defect diagnosis unit (200) provided in the battery diagnosis device (10) of FIG. 1.

[0044] Referring to FIGS. 1 and FIGS. 4, the battery failure diagnosis unit (200) may further include a measurement data reliability verification unit (220).

[0045] The measurement data reliability verification unit (220) above may be configured to determine the similarity of the graph trends of the first Nyquist plot and the second Nyquist plot. In this case, the graph in the form of a dotted line in FIG. 4 may be the first Nyquist plot, and the graph in the form of repeating 'X' dots may be the second Nyquist plot.

[0046] Specifically, the measurement data reliability verification unit (220) is, on the second Nyquist plot, the starting point (Z0) of the semicircle of the second Nyquist plot and the second AC impedance data at the semicircle of the second Nyquist plot. Between the points where the negative value of the imaginary component (-Zimg) is maximum, the second AC impedance data It is possible to verify whether the imaginary component (Zimg) is continuously decreasing (1st verification).

[0047] In addition, the measurement data reliability verification unit (220) [is] the second AC impedance data in the semicircle of the second Nyquist plot on the second Nyquist plot. Between the point where the negative value of the imaginary component (-Zimg) is maximum and the semicircle end point (Zmin) of the second Nyquist plot, it is possible to verify whether the imaginary component (Zimg) of the second AC impedance data continuously increases (second verification).

[0048] Additionally, the measurement data reliability verification unit (220) [describes] the second AC impedance data between the semicircle end point (Zmin) of the second Nyquist plot and the last measurement point (Zend) of the second AC impedance data on the second Nyquist plot. It is possible to verify whether the imaginary component (Zimg) is continuously decreasing (third verification).

[0049] Here, the first to third verifications may be to determine whether the increasing or decreasing trend of the graph of the first Nyquist plot and the increasing or decreasing trend of the graph of the second Nyquist plot are similar, based on each judgment point of the first Nyquist plot as shown in FIG. 4.

[0050] At this time, the measurement data reliability verification unit (220) can determine the similarity of the increase / decrease trend of the graphs of the first Nyquist plot and the second Nyquist plot by performing at least one of the first to third verifications. In this way, by verifying the reliability of the second AC impedance data measured for the second battery, which is the battery subject to defect diagnosis, the accuracy of the precise diagnosis of the second battery defect by the first defect diagnosis unit (230) and the second defect diagnosis unit (240) described later can be increased.

[0051] FIG. 5 is a diagram exemplarily illustrating a battery defect type diagnosis using a Nyquist plot by the first defect diagnosis unit (230) and the second defect diagnosis unit (240) of the battery defect diagnosis unit (200) provided in the battery diagnosis device (10) of FIG. 1.

[0052] Referring to FIGS. 1 and FIGS. 5, the battery defect diagnosis unit (220) may further include a primary defect diagnosis unit (230).

[0053] The above-mentioned first defect diagnosis unit (230) may be configured to primarily diagnose a defect in the second battery by performing at least one of the following: a comparison between the first measurement point (Zstart) of the first AC impedance data on the first Nyquist plot and the first measurement point (Zstart) of the second AC impedance data on the second Nyquist plot, and a comparison between the last measurement point (Zend) of the first AC impedance data on the first Nyquist plot and the last measurement point (Zend) of the second AC impedance data on the second Nyquist plot.

[0054] That is, the first defect diagnosis unit (230) can perform at least one of the following among the judgment points on the first Nyquist plot: a comparison between the first measurement point (Zstart) of the first AC impedance data on the first Nyquist plot and the first measurement point (Zstart) of the second AC impedance data on the second Nyquist plot, and a comparison between the last measurement point (Zend) of the first AC impedance data on the first Nyquist plot and the last measurement point (Zend) of the second AC impedance data on the second Nyquist plot.

[0055] According to this configuration, the first defect diagnosis unit (230) can determine whether the overall shape of the first Nyquist plot and the overall shape of the second Nyquist plot are similar by performing at least one of the comparison between the starting point of the first Nyquist plot (corresponding to the first measurement point (Zstart) of the first AC impedance data) and the starting point of the second Nyquist plot (corresponding to the first measurement point (Zstart) of the second AC impedance data) and the comparison between the ending point of the first Nyquist plot (the last measurement point (Zend) of the first AC impedance data) and the ending point of the second Nyquist plot (the last measurement point (Zend) of the second AC impedance data).

[0056] For example, by performing at least one of the comparison between the first measurement point (Zstart) of the first AC impedance data on the first Nyquist plot and the first measurement point (Zstart) of the second AC impedance data on the second Nyquist plot by the first defect diagnosis unit (230), and the comparison between the last measurement point (Zend) of the first AC impedance data on the first Nyquist plot and the last measurement point (Zend) of the second AC impedance data on the second Nyquist plot, as exemplarily shown in FIG. 5, a defect diagnosis case of the second battery, such as (1) measurement data error, (2) over-discharge, (3) severe battery damage, etc., can be determined.

[0057] In this way, the primary defect diagnosis unit (230) can primarily diagnose the defect of the second battery by determining the overall shape similarity between the first Nyquist plot and the second Nyquist plot.

[0058] FIG. 6 is a diagram exemplarily showing the raw values ​​of judgment points on a first Nyquist plot for battery failure diagnosis by the first failure diagnosis unit (230) of the battery failure diagnosis unit (200) provided in the battery diagnosis device (10) of FIG. 1 and battery failure diagnosis by the raw data diagnosis unit (242) in the second failure diagnosis unit (240).

[0059] At this time, in FIG. 6, the raw values ​​of the judgment points on the first Nyquist plot can be displayed according to the SOC (state of charge) of the first battery at room temperature (25℃).

[0060] Referring to FIGS. 1 and FIGS. 6, the battery defect diagnosis unit (200) may further include a secondary defect diagnosis unit (240).

[0061] The above secondary defect diagnosis unit (240) may be configured to perform at least one of the following: a comparison between the semicircle starting point (ZO) of the first Nyquist plot and the semicircle starting point (ZO) of the second Nyquist plot; a comparison between the semicircle ending point (Zmin) of the first Nyquist plot and the semicircle ending point (Zmin) of the second Nyquist plot; and a comparison between the point (Zmax) where the negative value (-Zimg) of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot and the point (Zmax) where the negative value (-Zimg) of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot.

[0062] That is, the secondary defect diagnosis unit (240) can diagnose the defect of the second battery more precisely by comparing in detail the judgment points in the semicircle area of ​​the first Nyquist plot (the starting point of the semicircle of the first Nyquist plot (ZO), the ending point of the semicircle of the first Nyquist plot (Zmin), the point where the negative value of the imaginary component of the first AC impedance data (-Zimg) is maximum in the semicircle of the first Nyquist plot (Zmax)) and the judgment points in the semicircle area of ​​the second Nyquist plot (the starting point of the semicircle of the second Nyquist plot (ZO), the ending point of the semicircle of the second Nyquist plot (Zmin), the point where the negative value of the imaginary component of the second AC impedance data (-Zimg) is maximum in the semicircle of the second Nyquist plot (Zmax)).

[0063] By this secondary defect diagnosis unit (240), as exemplarily shown in FIG. 5, a second battery defect diagnosis case can be determined, such as (1) measurement data error, (2) over-discharge, (3) severe battery damage, (4) contact resistance abnormality, (5) internal battery micro-short circuit, (6) battery electrode micro-interface abnormality. At this time, the second battery defect diagnosis case determined by the secondary defect diagnosis unit (240) may be more diverse than the second battery defect diagnosis case determined by the primary defect diagnosis unit (230).

[0064] Here, the secondary defect diagnosis unit (240) may include a raw data diagnosis unit (242).

[0065] The above raw data diagnostic unit (242) can secondarily diagnose a defect in the second battery based on at least one of the starting point (ZO) of the first Nyquist plot semicircle, the ending point (Zmin) of the first Nyquist plot semicircle, and the point (Zmax) where the negative value (-Zimg) of the imaginary component of the first AC impedance data is maximum in the first Nyquist plot semicircle.

[0066] That is, the raw data diagnostic unit (242) may be configured to secondarily diagnose a defect in the second battery by performing at least one of the following: a comparison between the semicircle starting point (ZO) of the first Nyquist plot and the semicircle starting point (ZO) of the second Nyquist plot; a comparison between the semicircle ending point (Zmin) of the first Nyquist plot and the semicircle ending point (Zmin) of the second Nyquist plot; and a comparison between the point (Zmax) where the negative value (-Zimg) of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot and the point (Zmax) where the negative value (-Zimg) of the imaginary component of the second AC impedance data is maximum.

[0067] FIG. 7 is a diagram exemplarily showing judgment parameter values ​​derived by constructing an equivalent circuit model (ECM) based on a first Nyquist plot for diagnosing battery defects in the equivalent circuit model diagnosis unit (244) of the secondary defect diagnosis unit (240) of the battery defect diagnosis unit (200) provided in the battery diagnosis device (10) of FIG. 1. FIG. 8 is a diagram illustrating an exemplary equivalent circuit model constructed by the equivalent circuit model diagnostic unit (244). However, the equivalent circuit model is not limited to the example shown in FIG. 8.

[0068] At this time in Fig. 7, The determination parameter values ​​derived by constructing an equivalent circuit model based on the first Nyquist plot can be displayed for each SOC (state of charge) of the first battery at room temperature (25℃).

[0069] Referring to FIGS. 1, 7 and 8, the secondary defect diagnosis unit (240) may further include an equivalent circuit model diagnosis unit (244).

[0070] The above equivalent circuit model diagnostic unit (244) may be configured to secondarily diagnose a defect in the second battery by comparing the judgment parameter value derived by constructing an equivalent circuit model based on the first Nyquist plot with the measurement parameter value derived by constructing an equivalent circuit model based on the second Nyquist plot.

[0071] In one embodiment, when the equivalent circuit model diagnostic unit (244) constructs an equivalent circuit model based on the first Nyquist plot, it can construct an equivalent circuit model based on inductance (L1), stray resistance (Rst), electrolyte resistance (Rs), film resistance (Rf), film capacitance (Cf), electric double layer capacitance (Cdl=CPE), charge transfer resistance (Rct), and capacitance (CPE1) considering diffusion phenomena within the battery active material, as shown in FIG. 8.

[0072] And the equivalent circuit model diagnostic unit (244) can derive judgment parameters (e.g., Rs, Rp, CPE-T, CPE-P) by constructing an equivalent circuit model according to the Complex Nonlinear Least Square (CNLS) fitting method, for example, on the first Nyquist plot.

[0073] At this time, Rs can correspond to the value of the real component (Zre) of the first AC impedance data at the semicircle starting point (ZO) of the first Nyquist plot.

[0074] In addition, Rp can correspond to the value at the point (Zmax) where the negative value (-Zimg) of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot.

[0075] In addition, CPE-T is a parameter representing the magnitude of the CPE and can correspond to the value of the real component (Zre) of the first AC impedance data at the last measurement point (Zend) of the first AC impedance data on the first Nyquist plot.

[0076] In addition, CPE-P is a parameter indicating whether the CPE is close to resistance or close to capacitor, and can correspond to the value of the imaginary component (Zimg) of the first AC impedance data at the last measurement point (Zend) of the first AC impedance data on the first Nyquist plot.

[0077] Additionally, the equivalent circuit model diagnostic unit (244) can derive measurement parameters (e.g., Rs, Rp, CPE-T, CPE-P) by constructing an equivalent circuit model according to the CNLS fitting method for the second Nyquist plot, for example.

[0078] At this time, Rs can correspond to the value of the real component (Zre) of the second AC impedance data at the semicircle starting point (ZO) of the second Nyquist plot.

[0079] In addition, Rp can correspond to the value at the point (Zmax) where the negative value (-Zimg) of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot.

[0080] In addition, CPE-T is a parameter representing the magnitude of the CPE and can correspond to the value of the real component (Zre) of the second AC impedance data at the last measurement point (Zend) of the second AC impedance data on the second Nyquist plot.

[0081] In addition, CPE-P is a parameter indicating whether the CPE is close to resistance or close to capacitor, and can correspond to the value of the imaginary component (Zimg) of the second AC impedance data at the last measurement point (Zend) of the second AC impedance data on the second Nyquist plot.

[0082] And the equivalent circuit model diagnostic unit (244) can be configured to secondarily diagnose the defect of the second battery by comparing the judgment parameter value derived by constructing an equivalent circuit model based on the first Nyquist plot as described above with the measurement parameter value derived by constructing an equivalent circuit model based on the second Nyquist plot.

[0083] According to this embodiment, after constructing an equivalent circuit model for a first battery that is a normal battery and a second battery that is a battery to be diagnosed as defective, the accuracy of diagnosing battery defects can be further improved by comparing simplified judgment parameter values ​​with measurement parameters.

[0084] FIG. 9 is a diagram exemplarily showing the battery defect judgment conditions and battery diagnosis results by the first defect diagnosis unit (230) and the second defect diagnosis unit (240).

[0085] Referring to FIG. 9, the primary defect diagnosis unit (230) can, for example, diagnose the defect type of the second battery as "severe battery damage" when it is determined that the value at the first measurement point (Zimg_start) of the imaginary component of the second AC impedance data on the second Nyquist plot is less than 0, or that the value at the first measurement point (Zre_start) of the real component of the second AC impedance data on the second Nyquist plot is greater than three times the value at the first measurement point (Zre_start_std) of the real component of the first AC impedance data on the first Nyquist plot.

[0086] Additionally, the first defect diagnosis unit (230) can diagnose the defect type of the second battery as "over-discharge" if it is determined that the value at the last measurement point (Zimg_end) of the imaginary component of the second AC impedance data on the second Nyquist plot is greater than three times the value at the last measurement point (Zimg_end_std) of the imaginary component of the first AC impedance data on the first Nyquist plot.

[0087] Additionally, the raw data diagnostic unit (242) can diagnose the defect type of the second battery as "severe battery damage" if, for example, the value of the real component (Zre_0) of the second AC impedance data at the starting point of the semicircle of the second Nyquist plot is greater than 2.5 times the value of the real component (Zre_0_std) of the first AC impedance data at the starting point of the semicircle of the first Nyquist plot, or the value of the point (Zimg_max) where the negative value of the imaginary component of the second AC impedance data is maximum at the semicircle of the second Nyquist plot is greater than 2 times the value of the point (Zimg_max_std) where the negative value of the imaginary component of the first AC impedance data is maximum at the semicircle of the first Nyquist plot.

[0088] Additionally, the equivalent circuit model diagnostic unit (244) can diagnose the defect type of the second battery as "severe battery damage" when, for example, the value of Rs, one of the measurement parameter values ​​derived by constructing an equivalent circuit model based on the second Nyquist plot, is greater than 2.5 times the value of Rs_std, one of the judgment parameter values ​​derived by constructing an equivalent circuit model based on the first Nyquist plot, or the value of Rp, one of the measurement parameter values ​​derived by constructing an equivalent circuit model based on the second Nyquist plot, is greater than 2 times the value of Rp_std, one of the judgment parameter values ​​derived by constructing an equivalent circuit model based on the first Nyquist plot.

[0089] As described above, with reference to the configuration and FIG. 9, various defect conditions of the battery can be diagnosed more precisely through the first defect diagnosis unit (230) and the second defect diagnosis unit (230).

[0090] According to the battery diagnostic device (10) of the present invention, the defect of the second battery can be accurately measured through a precise diagnosis based on a plurality of comparison methods (e.g., comparison according to a measurement data reliability verification unit (220), a first defect diagnosis unit (230), and a second defect diagnosis unit (240)) for a first Nyquist plot in which judgment points constituting the shape of the Nyquist plot are displayed using first AC impedance data measured for a first battery which is a normal battery, and a second Nyquist plot in which measurement points constituting the shape of the Nyquist plot are displayed using second AC impedance data measured for a second battery which is a battery subject to defect diagnosis.

[0091] FIG. 10 is a flowchart illustrating a battery diagnostic method according to one embodiment of the present invention.

[0092] Referring to FIG. 10, a battery diagnostic method according to one embodiment of the present invention includes the following steps S1 and S2.

[0093] In the above S1 step, a first Nyquist plot is constructed using first AC impedance data, which is reference AC impedance data measured for a first battery that is a normal battery at different frequencies using electrochemical impedance spectroscopy, and judgment points constituting the shape of the Nyquist plot are displayed. At this time, the above S1 step can be performed by the aforementioned diagnostic model configuration unit (100).

[0094] In the above S2 step, a second Nyquist plot is constructed using electrochemical impedance spectroscopy and second AC impedance data measured for the second battery, which is the battery subject to defect diagnosis at different frequencies, to display measurement points that constitute the shape of the Nyquist plot, and the defect of the second battery is diagnosed by comparing the first Nyquist plot and the second Nyquist plot. At this time, the above S2 step may be performed by the aforementioned battery defect diagnosis unit (200).

[0095] As described above, although the present invention has been explained by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0096] Meanwhile, although terms indicating directions such as up, down, left, right, front, and back have been used in this invention, these terms are used merely for convenience of explanation, and it is obvious to those skilled in the art that they may vary depending on the position of the object or the position of the observer. Explanation of the symbols

[0097] 10: Battery Diagnostic Device 100: Diagnostic model components 200: Battery Fault Diagnosis Unit 210: Measurement Data Configuration Section 220 : Measurement Data Reliability Verification Section 230 : Primary defect diagnosis unit 240 : Secondary defect diagnosis unit 242 : Raw Data Diagnostics Unit 244 : Equivalent Circuit Model Diagnostic Section

Claims

Claim 1 A diagnostic model component that constructs a first Nyquist plot in which judgment points constituting the shape of the Nyquist plot are displayed, using first AC impedance data, which is reference AC impedance data measured for a first battery that is a normal battery at different frequencies using electrochemical impedance spectroscopy (EIS); and includes a battery defect diagnosis unit configured to construct a second Nyquist plot with measurement points constituting the shape of the Nyquist plot using second AC impedance data measured for a second battery, which is a battery subject to defect diagnosis at different frequencies using the electrochemical impedance spectroscopy described above, and to diagnose a defect in the second battery by comparing the first Nyquist plot and the second Nyquist plot. The battery defect diagnosis unit includes a first defect diagnosis unit and a second defect diagnosis unit. The first defect diagnosis unit primarily diagnoses a defect in the second battery by performing at least one of a comparison between the first measurement point of the first AC impedance data on the first Nyquist plot and the first measurement point of the second AC impedance data on the second Nyquist plot, and a comparison between the last measurement point of the first AC impedance data on the first Nyquist plot and the last measurement point of the second AC impedance data on the second Nyquist plot. The second defect diagnosis unit compares the semicircle starting point of the first Nyquist plot and the second Comparison with the starting point of the semicircle of the Nyquist plot,A second defect of the second battery is diagnosed by performing at least one of a comparison between the end point of the semicircle of the first Nyquist plot and the end point of the semicircle of the second Nyquist plot, and a comparison between the point where the negative value of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot and the point where the negative value of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot; and the second defect diagnosis unit comprises a raw data diagnosis unit configured to secondarily diagnose the defect of the second battery based on at least one of the start point of the semicircle of the first Nyquist plot, the end point of the semicircle of the first Nyquist plot, and the point where the negative value of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot. and further includes an equivalent circuit model diagnostic unit configured to secondarily diagnose a defect in the second battery by comparing a judgment parameter value derived by constructing an equivalent circuit model based on the first Nyquist plot with a measurement parameter value derived by constructing an equivalent circuit model based on the second Nyquist plot, wherein the first defect diagnostic unit is configured to diagnose the defect type of the second battery as "severe battery damage" if it is determined that the value at the first measurement point (Zimg_start) of the imaginary component of the second AC impedance data on the second Nyquist plot is less than 0, or the value at the first measurement point (Zre_start) of the real component of the second AC impedance data on the second Nyquist plot is greater than three times the value at the first measurement point (Zre_start_std) of the real component of the first AC impedance data on the first Nyquist plot, and the first defect diagnostic unitIf it is determined that the value at the last measurement point (Zimg_end) of the imaginary component of the second AC impedance data on the second Nyquist plot is greater than three times the value at the last measurement point (Zimg_end_std) of the imaginary component of the first AC impedance data on the first Nyquist plot, the defect type of the second battery is diagnosed as "over-discharge", and the raw data diagnosis unit is configured to diagnose that the value of the real component (Zre_0) of the second AC impedance data at the semicircle starting point of the second Nyquist plot is greater than 2.5 times the value of the real component (Zre_0_std) of the first AC impedance data at the semicircle starting point of the first Nyquist plot, or that the value at the point (Zimg_max) where the negative value of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot is the second AC impedance data at the semicircle of the first Nyquist plot A battery diagnostic device characterized by being configured to diagnose the defect type of the second battery as "severe battery damage" when it is determined that the negative value of the imaginary component of the AC impedance data is greater than twice the value at the point where it is maximum (Zimg_max_std), and the equivalent circuit model diagnostic unit is configured to diagnose the defect type of the second battery as "severe battery damage" when it is determined that the value of Rs, one of the measurement parameter values ​​derived by constructing an equivalent circuit model based on the second Nyquist plot, is greater than 2.5 times the value of Rs_std, one of the judgment parameter values ​​derived by constructing an equivalent circuit model based on the first Nyquist plot, or when the value of Rp, one of the measurement parameter values ​​derived by constructing an equivalent circuit model based on the second Nyquist plot, is greater than twice the value of Rp_std, one of the judgment parameter values ​​derived by constructing an equivalent circuit model based on the first Nyquist plot. Claim 2 A battery diagnostic device according to claim 1, wherein the diagnostic model component is configured to display the judgment points on the first Nyquist plot as the starting point of the semicircle of the first Nyquist plot, the ending point of the semicircle of the first Nyquist plot, the point where the negative value of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot, the first measurement point of the first AC impedance data, and the last measurement point of the first AC impedance data. Claim 3 A battery diagnostic device according to claim 2, wherein the battery defect diagnosis unit comprises: a measurement data configuration unit configured to form the second Nyquist plot; and a measurement data reliability verification unit configured to determine the similarity of the graph trends of the first Nyquist plot and the second Nyquist plot. Claim 4 A battery diagnostic device according to claim 3, wherein the measurement data configuration unit is configured to display the measurement points on the second Nyquist plot as the starting point of the semicircle of the second Nyquist plot, the ending point of the semicircle of the second Nyquist plot, the point where the negative value of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot, the first measurement point of the second AC impedance data, and the last measurement point of the second AC impedance data. Claim 5 A battery diagnostic device according to claim 4, wherein the measurement data reliability verification unit is configured to perform at least one of the following: verifying whether the imaginary component of the second AC impedance data continuously decreases between the starting point of the semicircle of the second Nyquist plot and the point where the negative value of the imaginary component of the second AC impedance data is maximum on the semicircle of the second Nyquist plot on the second Nyquist plot; verifying whether the imaginary component of the second AC impedance data continuously increases between the point where the negative value of the imaginary component of the second AC impedance data is maximum on the semicircle of the second Nyquist plot on the second Nyquist plot and the end point of the semicircle of the second Nyquist plot on between the end point of the semicircle of the second Nyquist plot and the last measurement point of the second AC impedance data. Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 A battery diagnostic method performed by a battery diagnostic device, comprising the step of constructing a first Nyquist plot in which judgment points constituting the shape of a Nyquist plot are displayed using first AC impedance data, which is reference AC impedance data measured for a first battery that is a normal battery at different frequencies using electrochemical impedance spectroscopy; The method comprises the step of constructing a second Nyquist plot in which measurement points constituting the shape of the Nyquist plot are displayed using second AC impedance data measured for a second battery, which is a battery subject to defect diagnosis, at different frequencies using the electrochemical impedance spectroscopy described above, and diagnosing a defect in the second battery by comparing the first Nyquist plot with the second Nyquist plot; wherein the battery diagnostic device primarily diagnoses a defect in the second battery by performing at least one of a comparison between the first measurement point of the first AC impedance data on the first Nyquist plot and the first measurement point of the second AC impedance data on the second Nyquist plot, and a comparison between the last measurement point of the first AC impedance data on the first Nyquist plot and the last measurement point of the second AC impedance data on the second Nyquist plot; and wherein the battery diagnostic device performs a comparison between the semicircle starting point of the first Nyquist plot and the semicircle starting point of the second Nyquist plot, and the semicircle ending point of the first Nyquist plot. A secondary diagnosis of a defect in the second battery is performed by performing at least one of a comparison between a point and the end point of the semicircle of the second Nyquist plot, and a comparison between a point where the negative value of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot and a point where the negative value of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot, and the battery diagnostic device comprises: a starting point of the semicircle of the first Nyquist plot,The battery diagnostic device is configured to secondarily diagnose a defect in the second battery based on at least one of the end point of the semicircle of the first Nyquist plot and the point in the semicircle of the first Nyquist plot where the negative value of the imaginary component of the first AC impedance data is maximum, and to secondarily diagnose a defect in the second battery by comparing a judgment parameter value derived by constructing an equivalent circuit model based on the first Nyquist plot with a measurement parameter value derived by constructing an equivalent circuit model based on the second Nyquist plot, wherein the battery diagnostic device is configured such that the value at the first measurement point (Zimg_start) of the imaginary component of the second AC impedance data on the second Nyquist plot is less than 0, or the value at the first measurement point (Zre_start) of the real component of the second AC impedance data on the second Nyquist plot is greater than three times the value at the first measurement point (Zre_start_std) of the real component of the first AC impedance data on the first Nyquist plot. If determined, the battery diagnostic device is configured to diagnose the defect type of the second battery as "severe battery damage," and if the value at the last measurement point (Zimg_end) of the imaginary component of the second AC impedance data on the second Nyquist plot is determined to be greater than three times the value at the last measurement point (Zimg_end_std) of the imaginary component of the first AC impedance data on the first Nyquist plot, the battery diagnostic device is configured to diagnose the defect type of the second battery as "over-discharge," and if the value of the real component (Zre_0) of the second AC impedance data at the semicircle starting point of the second Nyquist plot is greater than 2.5 times the value of the real component (Zre_0_std) of the first AC impedance data at the semicircle starting point of the first Nyquist plot,If it is determined that the value at the point (Zimg_max) where the negative value of the imaginary component of the second AC impedance data is maximum in the semicircle of the second Nyquist plot is greater than twice the value at the point (Zimg_max_std) where the negative value of the imaginary component of the first AC impedance data is maximum in the semicircle of the first Nyquist plot, the battery diagnostic device is configured to diagnose the defect type of the second battery as "severe battery damage," and the battery diagnostic device determines that the value of Rs, one of the measurement parameter values ​​derived by constructing an equivalent circuit model based on the second Nyquist plot, is greater than 2.5 times the value of Rs_std, one of the judgment parameter values ​​derived by constructing an equivalent circuit model based on the first Nyquist plot, or that the value of Rp, one of the measurement parameter values ​​derived by constructing an equivalent circuit model based on the second Nyquist plot, is one of the judgment parameter values ​​derived by constructing an equivalent circuit model based on the first Nyquist plot A battery diagnosis method characterized by being configured to diagnose the defect type of the second battery as "severe battery damage" when it is determined that the value of Rp_std is greater than twice.

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