Battery diagnosis apparatus and battery diagnosis method

Abstract

A battery diagnosis apparatus and a battery diagnosis method are disclosed. The battery diagnosis apparatus according to the present invention comprises: a data processing unit which acquires a differential profile representing the charge-discharge characteristics of a battery cell; a calculation unit which, when a plurality of peak points exist in the differential profile, determines a peak comparison value on the basis of a first peak point and a second peak point that are any two of the plurality of peak points; and a diagnosis unit which diagnoses a state of the battery cell on the basis of the peak comparison value.

Description

Battery diagnostic device and battery diagnostic method

[0001] The present invention relates to a technology for diagnosing the condition of a battery by analyzing a differential profile reflecting the charge / discharge characteristics of active materials of the battery.

[0002] This application claims priority to Korean Patent Application No. 10-2023-0175821, filed on December 6, 2023, and all contents disclosed in the specification and drawings of that application are incorporated herein by reference.

[0003]

[0004] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has rapidly increased, and the development of electric vehicles, energy storage batteries, robots, and satellites has been in full swing, research into high-performance batteries capable of repeated charging and discharging is actively being conducted.

[0005] Currently commercialized batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium batteries. Among these, lithium batteries are receiving attention for their advantages of being able to charge and discharge freely, having a very low self-discharge rate, and having a high energy density, as they have almost no memory effect compared to nickel-based batteries.

[0006] Unlike fossil fuel-based energy generation, secondary cell-based batteries generate energy through electrochemical reactions, so as the charge-discharge cycle continues or is repeated, they cannot maintain the performance they had when they were first manufactured, that is, in the BOL (Beginning Of Life) state, and gradually deteriorate or age.

[0007] In this way, as the battery continues to be used (charged and discharged), its usability decreases due to deterioration in capacity and output, and its safety also becomes a risk factor. Therefore, the current status of the battery needs to be accurately diagnosed to maintain continuity of normal operation, control for limited use, determine replacement timing, and improve the efficiency of battery reuse or recycling.

[0008] Batteries are typically used in groups of multiple cells or banks, electrically connected in parallel or other configurations. Therefore, if any of the battery cells are abnormal, the overall operating performance of the battery may deteriorate.

[0009] Therefore, accurately diagnosing the current status of a battery cell and performing appropriate follow-up control accordingly is essential in maintaining the normal operating performance of a battery as an assembly of multiple battery cells.

[0010] Recently, in order to improve the operating characteristics of battery cells, mixed cathode materials (e.g., NCM, NCA, etc.) and mixed anode materials in which multiple active materials such as nickel, cobalt, manganese, and aluminum are mixed in an appropriate ratio have been widely applied.

[0011] In the case of mixed cathode materials, since multiple active materials with different charge / discharge characteristics are mixed, a degradation deviation occurs in which a specific active material degrades more than the others. This degradation deviation is amplified or accelerated when the battery cell is repeatedly used (charge / discharged). These degradation characteristics of mixed cathode materials may also be common to mixed anode materials. Furthermore, the difference in charge / discharge characteristics between at least one cathode active material and at least one anode active material may also increase gradually as the battery cell degrades.

[0012] Therefore, it is necessary to accurately track the status of battery cells to ensure the normal operation and stable operation of battery cells containing two or more types of active materials.

[0013]

[0014] The present invention has been devised to solve the above problems, and its purpose is to provide a battery diagnosis device and method that can quickly and reliably diagnose the current state of a battery cell using a differential profile of the battery cell that can be obtained and generated through a simple method.

[0015] Other objects and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0016]

[0017] A battery diagnosis device according to one aspect of the present invention includes a data processing unit that obtains a differential profile representing a charge / discharge characteristic of a battery cell, a calculation unit that determines a peak comparison value based on a first peak point and a second peak point, which are any two of the plurality of peak points, when a plurality of peak points exist in the differential profile, and a diagnosis unit that diagnoses a state of the battery cell based on the peak comparison value.

[0018] The above first peak point and second peak point may represent the charge / discharge characteristics of the two active materials included in the battery cell.

[0019] The above battery diagnostic device may further include a management control unit that controls charging and discharging of the battery cell to be limited when the battery cell is diagnosed as abnormal.

[0020] The above calculation unit may determine, among the plurality of peak points, one peak point having a minimum voltage difference from the reference peak point as the first peak point. The calculation unit may determine, among the plurality of peak points, another peak point having a voltage value lower than the first peak point and a minimum voltage difference from the first peak point as the second peak point.

[0021] The above operation unit can determine the peak comparison value based on a ratio between the differential capacity value of the first peak point and the differential capacity value of the second peak point.

[0022] The above diagnostic unit can diagnose the battery cell as an abnormal cell if the peak comparison value exceeds the reference comparison value. The above diagnostic unit can diagnose the battery cell as normal if the peak comparison value is less than or equal to the reference comparison value.

[0023] The above diagnostic unit can generate diagnostic information indicating that the battery cell is abnormal when the battery cell is diagnosed as abnormal.

[0024] The above diagnostic unit can diagnose the state of the battery cell based on the history data of the peak comparison value when a single peak point exists in the differential profile.

[0025] The above diagnostic unit can diagnose that the battery cell is abnormal if at least one previous peak comparison value is confirmed from the history data.

[0026] The above diagnostic unit can diagnose that the battery cell is normal if a previous peak comparison value is not confirmed from the above history data.

[0027] A battery pack according to another aspect of the present invention includes the battery diagnostic device.

[0028] An electric vehicle according to another aspect of the present invention includes the battery diagnostic device.

[0029] A battery diagnosis method according to another aspect of the present invention includes the steps of: obtaining a differential profile representing charge / discharge characteristics of a battery cell; determining a peak comparison value based on a first peak point and a second peak point, which are any two of the plurality of peak points, when a plurality of peak points exist in the differential profile; and diagnosing a state of the battery cell based on the peak comparison value.

[0030] The step of determining the peak comparison value may include the step of determining, among the plurality of peak points, one having a minimum voltage difference from a reference peak point as the first peak point, and the step of determining, among the plurality of peak points, another having a voltage value lower than that of the first peak point and a minimum voltage difference from the first peak point as the second peak point.

[0031] The step of determining the above peak comparison value may determine the peak comparison value based on a ratio between the differential capacity value of the first peak point and the differential capacity value of the second peak point.

[0032]

[0033] According to at least one of the embodiments of the present invention, it is possible to organically incorporate changes in characteristics due to deterioration of a battery cell into a data analysis process, thereby effectively diagnosing the current state of the battery cell, etc. in a more simplified manner.

[0034] In addition, according to at least one of the embodiments of the present invention, the current state of the battery cell can be diagnosed more simply and quickly through analysis of a differential profile representing the characteristics of the battery cell and a process of utilizing the same, and by utilizing the differential profile by updating it in a time series manner, the current state of the battery cell, which dynamically changes, can be reflected more practically.

[0035] In addition, according to at least one of the embodiments of the present invention, the degree of degradation of a battery cell can be generated and compared as quantified numerical information, so that the current state of the battery cell can be diagnosed more precisely, and subsequent control processes such as charge / discharge restrictions can be implemented more effectively using this.

[0036] Furthermore, the process according to the present invention can be implemented through software that can be installed in a BMS or the like that is generally applied to a battery device or system, thereby providing higher expandability.

[0037] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0038]

[0039] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0040] FIG. 1 is a block diagram illustrating a detailed configuration of a battery diagnostic device according to one embodiment of the present invention.

[0041] Figure 2 is a block diagram exemplarily showing the detailed configuration of the operation unit illustrated in Figure 1.

[0042] Figure 3 is a block diagram exemplarily showing the detailed configuration of the diagnostic unit illustrated in Figure 1.

[0043] FIG. 4 is a flowchart illustrating a process according to one embodiment of the present invention for diagnosing the state of a battery cell.

[0044] Figure 5 is a flowchart exemplarily illustrating a process for generating a peak comparison value of a battery cell.

[0045] FIG. 6 is a flowchart illustrating a process according to one embodiment of the present invention for diagnosing the status of a battery cell.

[0046] Figure 7 is a detailed drawing of the differential profile of a battery cell and a scaled-up voltage region of interest of the differential profile.

[0047] Figure 8 is a diagram illustrating an example of characteristic points selected from a differential profile of a battery cell corresponding to a normal state.

[0048] FIG. 9 is a diagram illustrating an example of characteristic points selected from a differential profile of a battery cell corresponding to an abnormal state.

[0049] Figure 10 is a diagram exemplarily illustrating the time-series change of peak comparison values.

[0050] Figure 11 is a diagram explaining the voltage difference between two characteristic points.

[0051] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that conforms to the technical spirit of the present invention.

[0052] Accordingly, 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. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0053] Terms that include ordinal numbers, such as first, second, etc., are used to distinguish one of the various components from the rest, and are not used to limit the components by such terms.

[0054] Throughout the specification, when a part is said to "include" a component, this does not exclude other components, unless otherwise stated, but rather implies that other components may be included. Furthermore, terms such as "unit" used throughout the specification mean a unit that processes at least one function or operation, and may be implemented using hardware, software, or a combination of hardware and software.

[0055] Additionally, throughout the specification, when we say that a part is "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "indirectly connected" with other elements in between.

[0056] FIG. 1 is a block diagram showing a detailed configuration of a battery diagnosis device (100) according to one embodiment of the present invention, and FIG. 4 is a flowchart explaining a process according to one embodiment of the present invention for diagnosing the state of a battery cell.

[0057] Referring to FIGS. 1 and 4, the battery diagnostic device (100) may include a measuring unit (110), a profile processing unit (120), a data processing unit (130), a peak detection unit (140), a calculation unit (150), a diagnostic unit (160), and a management control unit (160).

[0058] The battery diagnostic device (100) can be implemented through various combinational applications of electronic components, parts, etc. (ASIC, chipset, logic circuit, register, communication modem, MCU, etc.), such as storage means, operation processing means, and input / output means. Therefore, each component of the battery diagnostic device (100) should be understood as being physically distinct or functionally or logically distinguishable. The same applies to each component of the operation unit (150) and the diagnostic unit (160) illustrated in FIGS. 2 and 3.

[0059] That is, since each component illustrated in the above drawing corresponds to a logical configuration for effectively explaining the technical idea of ​​the present invention, even if each component is configured integrated or separated, if the function performed by the logical configuration of the present invention can be realized, it should be interpreted as being within the scope of the present invention, and of course, if it is a component that performs the same or similar function, it should be interpreted as being within the scope of the present invention regardless of whether or not the name is consistent.

[0060] In addition, the battery diagnosis method according to the present invention can be implemented as a set or algorithm of processes related to data processing, handling, control, calculation, input / output, etc. It can be implemented as a combination of logical structures shown in Fig. 1, etc., and of course, it can be implemented as software that is installed and operated in a system, device, computer (or a device equivalent thereto), BMS, module, or sub-component thereof.

[0061] A battery diagnostic device (100) is provided to diagnose a normal or abnormal state of a battery cell (50). Depending on the embodiment, the battery diagnostic device (100) may be configured to organically link with other components or modules / devices to generate and output diagnostic data for the battery cell (50). Hereinafter, a battery cell (50) that is the subject of a status diagnosis may be referred to as a "target cell."

[0062] The target cell (50) may include two or more types of active materials. Each active material may be included in the positive or negative electrode of the target cell (50).

[0063] As positive electrode active materials, for example, Li2MnO3, LiNi a Co b Mn c O2(a, b, c≥0; a + b + c 1), LiFe x Mn 1-x PO4(x≥0), etc. The so-called manganese-rich (Mn-rich) is LiNi, which is a ternary (NMC) cathode material. a Co b Mn c It can be a cathode active material in which the specific gravity (c) of manganese in O2 is increased to a certain value (e.g., 0.5) or higher. LiFe x Mn 1-x PO4 can be referred to as an LMFP cathode material. Negative active materials include graphite and silicon-based active materials (e.g., Pure Si, SiO, SiC, etc.).

[0064] It goes without saying that the target cells (50) diagnosed and managed by the battery diagnostic device (100) may be provided in multiple numbers in a cell assembly, battery module, or battery pack, which is its upper assembly. In this case, the multiple target cells (50) may be electrically interconnected in a series, parallel, or series-parallel combination.

[0065] The measuring unit (110) may include at least one of a voltage sensor and a current sensor. The voltage sensor may measure the voltage of the target cell (50). The current sensor may measure the charge / discharge current flowing through the target cell (50). The measuring unit (110) may generate charge / discharge information (which may also be referred to as “measurement information”) indicating the voltage and / or current of the target cell (50) during the charge / discharge process of the target cell (50).

[0066] In step S400, the profile processing unit (120) can collect charge / discharge information of the target cell (50) from the measurement unit (110).

[0067] In step S410, the profile processing unit (120) can generate a battery profile of the target cell (50). Here, the battery profile (charge / discharge profile) may be a profile indicating a correspondence between the voltage and capacity (or SOC: State Of Charge) of the target cell (50).

[0068] The profile processing unit (120) can generate a battery profile by executing a process of mutually mapping the voltage time series and capacity time series (or SOC time series) of the target cell (50) based on a time index. The battery profile can be received and stored by the profile processing unit (120) from a separately provided external device or module, and utilized.

[0069] A battery profile may be a set or polynomial of data points representing the relationship between voltage and capacity of a target cell (50) or the relationship between voltage and SOC. Each data point of the battery profile may be a pair of voltage and capacity values ​​(or SOC) indexed at the same point in time (same measurement timing).

[0070] The voltage time series can represent the temporal change history of the voltage of the target cell (50). The current time series can represent the temporal change history of the current of the target cell (50). The capacity time series (or SOC time series) can be determined by applying ampere counting to the current time series.

[0071] SOC is a parameter that represents the current capacity relative to the maximum capacity as 0 to 1 or 0% to 100%, and various techniques and technologies such as current integration, equivalent circuit model, and Kalman filter can be applied. Depending on the embodiment, information on SOC that additionally reflects environmental information such as temperature information may be generated.

[0072] In step S420, the data processing unit (130) may generate a differential profile from the battery profile. Alternatively, the differential profile may be received and stored by the profile processing unit (120) from a separately provided external device or module, and utilized.

[0073] The differential profile may be a set or polynomial of data points representing the relationship between the voltage and differential capacitance of the target cell (50). Each data point of the differential profile may be a pair of voltage values ​​and differential capacitance values, indexed at the same point in time (same measurement timing).

[0074] Differential capacity is the capacity differentiated with respect to voltage, and can be expressed as "dQ / dV", and the unit can be [Ah / V]. When the X-axis of a two-dimensional coordinate corresponds to voltage and the Y-axis corresponds to differential capacity, the differential profile (differential capacity profile) can be expressed as a two-dimensional graph shape, as illustrated in Fig. 7, etc.

[0075] By applying functional processing such as symmetry movement and variable conversion, the technical idea of ​​the present invention can be applied regardless of whether the charge / discharge information that forms the basis of the battery profile is acquired during the charging process or the discharging process. At least one of the charging process and the discharging process of the target cell (50) can be conducted at a constant current (CC).

[0076] As the target cell (50) degrades, the charge / discharge characteristics of at least one active material of the target cell (50) may gradually change. In particular, there exists a voltage range in which the charge / discharge characteristics of a specific active material change significantly compared to the remaining active materials or the deviation in the charge / discharge characteristics between the active materials becomes excessive, and therefore, the state of the specific active material can be estimated by analyzing the corresponding voltage range.

[0077] Therefore, so that the charge / discharge characteristic deviation by active material can be clearly reflected in the data processing, the part corresponding to the voltage region of interest (HV, see FIG. 7) among the differential profiles can be set as the target of the diagnostic process according to the present invention. In FIG. 7, etc., the voltage region of interest (HV) is illustrated as 3.90 to 4.10 [V]. Alternatively, the differential profile may represent the relationship between the voltage and the differential capacity across the voltage region of interest (HV) instead of the available voltage range of the target cell (50).

[0078] The voltage region of interest (HV) may be predetermined to have a single peak point in the early life of the target cell (BC) (which may be referred to as the "Beginning of Life (BOL)"), but additional peak points may appear as the target cell (BC) degrades. This increase in the number of peak points is due to the peak differentiation phenomenon described below.

[0079] The reference voltage value can be said to be a boundary voltage (i.e., the lower limit of the voltage region of interest) that separates the voltage region of interest from the remaining voltage region within the entire voltage range of the differential profile. It goes without saying that the reference voltage value can be variably set depending on the specifications, type, etc. of the target cell (50). For example, in the case of a battery cell whose upper limit of the available voltage range is designed to be 4.20 [V], the reference voltage value can be set to 3.90 [V], which is lower than that.

[0080] Fig. 7 illustrates an example of a reference differential profile, and Figs. 8 and 9 illustrate an example of a differential profile of each battery cell (50).

[0081] Referring to Figure 7, the upper left corner shows a schematic illustration of a reference differential profile (RP), and the lower corner shows a portion of the reference differential profile (RP) corresponding to the voltage region of interest (HV) scaled up along the X-axis (voltage axis).

[0082] The reference differential profile (RP) may be acquired in advance, representing the correspondence between the voltage and differential capacity of a reference cell. For example, the reference cell may be a battery cell manufactured to have the same electrochemical characteristics and performance as when the target cell (50) is in a BOL state.

[0083] In step S430, the peak detection unit (140) can detect a peak point existing in the differential profile.

[0084] A peak point can refer to a boundary point where the slope trend of a battery profile reverses, i.e., a point where the sign of the slope increase rate changes (from positive to negative or from negative to positive). It refers to a point where a change in the shape of a bump or curve in a battery profile occurs, i.e., a transition between convexity (upward convex) and concave (downward convex). A peak point can be, for example, a maximum point, a minimum point, or an inflection point.

[0085] Since each peak point represents voltage-differential capacity information reflecting the charge / discharge characteristics of at least one active material of the target cell (50), it can be utilized as an important parameter indicating the current state of the target cell (50).

[0086] For convenience of explanation, each differential profile illustrated in FIGS. 7 to 9 is exemplified as being generated based on charge / discharge information acquired during the discharge process. In this case, each local minimum point located in the voltage region of interest (HV) can be detected as a peak point from the differential profile. A local minimum point on the differential profile may be a point where the sign of the slope in the differential profile changes from negative to positive. For example, CP1 and CP2 in FIGS. 8 and 9 are two local minimum points located in the differential profile of the target cell (50).

[0087] In step S440, the diagnostic unit (160) can determine whether a plurality of peak points having voltage values ​​within the voltage range of interest (HV) are detected from the differential profile of the target cell (50). That is, whether a peak splitting phenomenon due to a change in the charge / discharge characteristics of at least one active material of the target cell (50) occurs is determined in step S440.

[0088] If the value of step S440 is "No", the diagnostic unit (160) can diagnose the target cell (50) as a normal cell. As illustrated in FIG. 7, a specific voltage value (V) within the voltage region of interest (HV) is detected on the reference differential profile (RP) of the reference cell. R ) mapped to a single peak point (CP) R ) may exist. Therefore, if only one peak point is identified in the differential profile of the target cell (50), the diagnostic unit (160) can diagnose that the target cell (50) is in a normal state. Alternatively or additionally, an additional diagnostic process for the target cell (50) may be executed in step S445.

[0089] On the other hand, as illustrated in FIGS. 8 and 9, there may be two or more peak points on the differential profile of the target cell (50). In this case, the value of step S440 is “Yes”, and step S450 as a subsequent procedure may be executed.

[0090] In step S450, the calculation unit (150) may determine which two (CP1, CP2) of the plurality of peak points detected in step S430 are the first peak point and the second peak point. In this specification, the first peak point and the second peak point may be collectively referred to as "characteristic points." A specific example of selecting characteristic points will be described later.

[0091] Next, in step S460, the operation unit (150) determines a peak comparison value based on two characteristic points (CP1, CP2).

[0092] For reference, the calculation unit (150) can update history data indicating the change history of the peak comparison value each time a peak comparison value is determined. The calculation unit (150) can identify a previous peak comparison value based on the history data. The previous peak comparison value may refer to a peak comparison value determined prior to the currently determined peak comparison value.

[0093] In step S470, the diagnostic unit (160) can diagnose the status of the target cell (50) based on the peak comparison value determined by step S460.

[0094] The diagnostic unit (160) can compare the peak comparison value with the reference comparison value and determine whether the target cell (50) is normal or abnormal based on the comparison result. If the peak comparison value is greater than the reference comparison value, the diagnostic unit (160) can diagnose the target cell (50) as an abnormal cell. On the other hand, if the peak comparison value of the target cell (50) is less than the reference comparison value, the diagnostic unit (160) can diagnose the target cell (50) as a normal cell. The specific details of the diagnostic unit (160) diagnosing the target cell (50) will be described later.

[0095] Depending on the embodiment, for organic linkage with subsequent control processes or other configurations and time-series characteristic analysis, etc., it is preferable that the diagnostic unit (140) be configured to generate and store diagnostic information or history information that links time information determined to be a normal cell or an abnormal cell and identification information of a target cell (50).

[0096] At step S480, the diagnostic unit (160) can determine whether a preset termination condition is met. If the termination condition is determined to be unmet (step S480: NO), the process of the present invention described above can be applied cyclically. The termination condition may be, for example, a forced shutdown, a system shutdown, or an emergency event.

[0097] FIG. 2 is a block diagram exemplarily illustrating the detailed configuration of the operation unit (150) illustrated in FIG. 1, FIG. 5 is a flowchart exemplarily explaining a process for generating a peak comparison value of a battery cell (50), and FIG. 11 is a drawing explaining the voltage difference between two characteristic points. Hereinafter, embodiments of the present invention for generating a peak comparison value will be described in detail with reference to the drawings.

[0098] Referring to FIG. 2, the operation unit (150) may include at least one of a reference storage unit (151), a counting unit (153), a selection unit (155), and an operation processing unit (157). As previously discussed, each component of the operation unit (150) illustrated in FIG. 2 may also correspond to a physical configuration or a logical configuration.

[0099] For the reference cell, it is a battery cell with no or minimal deviation in the charge / discharge characteristics between active materials. Therefore, as shown in Fig. 7, a single peak point (CP) is present in the portion corresponding to a specific voltage range (HV) of the reference differential profile (RP), which is the differential profile of the reference cell. R) can be located. In order to distinguish it from the peak point of the target cell (50), etc., the peak point of the reference differential profile (RP) will be referred to as the 'reference peak point' below.

[0100] The reference storage unit (151) may have information about a reference peak point stored in advance. For example, if the reference differential profile (RP) is generated from a reference battery profile representing a voltage-capacity relationship as a characteristic during the discharge process of a reference cell, a local minimum point having a voltage value within the voltage range of interest (HV) in the reference differential profile (RP) may be the reference peak point.

[0101] In step S510, the counting unit (153) counts the number of peak points based on the peak detection data received from the peak detection unit (140).

[0102] In step S520, the counting unit (153) determines whether the number of peak points counted in step S510 is 2 or more. If the value of step S520 is "No", the method may proceed to step S525. If the value of step S520 is "Yes", the method may proceed to step S530.

[0103] In step S525, the counting unit (153) can generate result data indicating that the peak point is single. The result data can be output to the diagnosis unit (160). The diagnosis unit (160) can diagnose that the target cell (50) is normal based on the result data received from the counting unit (153).

[0104] In step S530, the selection unit (155) determines which two of the plurality of peak points are the first peak point and the second peak point. Specifically, the selection unit (155) may select one of the plurality of peak points, which has the smallest voltage difference from the reference peak point, as the first peak point. For example, referring to FIG. 8, among the voltage values ​​(V1, V2) of the two peak points (CP1, CP2), the voltage value (V) of the reference peak point is selected. R ) is relatively close to V1, so CP1 among CP1 and CP2 becomes the first peak point selected as the characteristic point.

[0105] When the target cell (50) degrades, the peak differentiation phenomenon occurs as described above, so that the number of peak points detected in the voltage region of interest (HV) may be 2 or more. In particular, the peak differentiation phenomenon may occur more distinctly as the cycle (use) is repeated due to the relative difference in the degree of degradation between two or more types of active materials in the positive and / or negative electrodes of the battery cell (50), as well as between the active materials of the positive and negative electrodes.

[0106] The selection unit (155) may determine another peak point among a plurality of peak points as the second peak point based on the first peak point (CP1). Specifically, among the peak points existing in the low-voltage region based on the voltage value of the first peak point (CP1), the peak point with the smallest voltage difference from the first peak point may be determined as the second peak point. For example, referring again to FIG. 8, the peak point (CP2) may be determined as the second peak point.

[0107] Although not shown, if the voltage value of the peak point having the minimum voltage difference with respect to the first peak point (CP1) is lower than the reference voltage value (e.g., 3.90 V), there is a very high possibility that the peak point is due to the charge / discharge characteristics of an active material different from the first peak point active material. Therefore, it is preferable that one of the plurality of peak points that satisfies the following conditions is determined as the second peak point: (i) having a voltage value lower than the voltage value of the first peak point, (ii) having a minimum voltage difference with respect to the first peak point, and (iii) having a voltage value higher than the reference voltage value.

[0108] In this way, when two characteristic points (CP1, CP2) that serve as criteria for determining excessive deviation in charge / discharge characteristics between active materials are selected, in step S540, the calculation processing unit (157) can compare the first and second peak points (CP1, CP2) to generate a peak comparison value of the target cell (50). The following formula can be used to determine the peak comparison value.

[0109] Formula

[0110]

[0111] Let us assume that the function f(V)=dQ / dV is a polynomial corresponding to the differential profile of the target cell (50) illustrated in Fig. 8. In the above equation, DR is the peak comparison value of the target cell (50), f(V1) is the differential capacity value of the first peak point (CP1), and f(V2) is the differential capacity value of the second peak point (CP2). As an example, the peak comparison value (DP) based on the two characteristic points (CP1, CP2) illustrated in Fig. 8 is f(V2) / f(V1) = dq 12 / dq 11 As another example, the peak comparison value (DP) based on two characteristic points (CP1, CP2) in Fig. 9 is f(V2) / f(V1) = dq 22 / dq 21For reference, profile 1 illustrated in FIG. 8 is a differential profile of the target cell (50) when the target cell (50) is in the first state, and profile 2 illustrated in FIG. 9 is a differential profile of the target cell (50) when the target cell (50) is in the second state, which is more degenerate than the first state.

[0112] In step S550, the operation processing unit (157) can output comparison data (e.g., peak comparison value) indicating the comparison result by step S540 to the diagnosis unit (160).

[0113] In step S560, the diagnostic unit (160) can determine whether a preset termination condition is satisfied. If the value of step S560 is "No," the above-described steps performed in the operation unit (150) can also be performed cyclically. Step S560 can be substantially the same as step S480.

[0114] The diagnostic process of the present invention can be configured to track changes in characteristics in a time series manner according to an increase in the usage period or cycling count of the target cell (50).

[0115] Therefore, the differential profile of the target cell (50) can be updated regularly or irregularly, and the peak detection unit (140) can re-perform the operation of selecting peak points from the updated differential profile. In addition, the operation unit (150) can be configured to re-perform the operation of determining the peak comparison value of the target cell (50) based on the peak points selected from the updated differential profile. The diagnosis unit (160) can track the status of the target cell (50) throughout the entire life of the target cell (50) through an operation of comparing the newly determined peak comparison value with a reference comparison value (S470).

[0116] The operation processing unit (157) can determine the voltage difference between two characteristic points. Referring to FIG. 11, D1 represents the voltage difference between two characteristic points detected from profile 1, and D2 represents the voltage difference between two characteristic points detected from profile 2.

[0117] The voltage difference between the two characteristic points may be a quantitative value representing a behavioral characteristic that increases as the degradation of the target cell (50) progresses. Therefore, by comparing the voltage difference between the two characteristic points with a reference voltage difference or by tracking the time-series change trend of the voltage difference between the two characteristic points, additional data representing the state of the target cell (50) can be acquired.

[0118] If the operation processing unit (157) further generates a voltage difference between the first and second peak points, the diagnosis unit (160) can diagnose the current state of the target cell (50) more precisely based on information about this voltage difference. For example, the diagnosis unit (160) may determine that the target cell (50) is abnormal if both the first condition that the peak comparison value is greater than the reference comparison value and the second condition that the voltage difference between the first and second peak points is greater than the reference voltage difference are satisfied.

[0119] FIG. 3 is a block diagram exemplarily illustrating a detailed configuration of a diagnostic unit (160) illustrated in FIG. 1, FIG. 6 is a flowchart explaining a process according to one embodiment of the present invention for diagnosing the state of a battery cell (50), and FIG. 10 is a drawing exemplarily explaining a time-series change in a peak comparison value.

[0120] Referring to FIGS. 3, 6 and 10, the diagnostic unit (160) may include a reference information storage unit (161), a diagnostic processing unit (165) and an information generation unit (167).

[0121] The reference information storage unit (161) may store information on a reference comparison value in advance. The reference comparison value may be information that is compared to the peak comparison value described above, and may be predetermined to be used to determine whether the target cell (50) is normal.

[0122] Even if multiple peak points exist in the voltage range of interest (HV) due to the peak differentiation phenomenon, if the two differential capacitance values ​​of the first peak point and the second peak point, which are highly related to the reference peak point, are at equal levels, the target cell (50) can be considered to be in a state where normal operation is possible. Accordingly, when the peak comparison value is determined according to the above formula, the reference comparison value can be set to 1.

[0123] It goes without saying that the reference comparison value can be variably set by additionally reflecting various information such as the safety level of the application device in which the target cell (50) is mounted, the service life of the target cell (50), capacity characteristics, SOH (State Of Health), types of active materials and / or a predetermined mixing ratio for the active materials.

[0124] In step S620, the diagnostic processing unit (165) can determine whether the peak comparison value of the target cell (50) received from the operation unit (150) is greater than the reference comparison value.

[0125] The graph illustrated in Fig. 10 represents the history data of peak comparison values ​​according to the increase in cycle number, with the X-axis representing the cycle number and the Y-axis representing the peak comparison value. The cycle number may refer to the number of times the target cell (50) is charged and discharged according to a predetermined charging protocol (e.g., constant current-constant voltage charging over an available voltage range) and a discharge protocol (e.g., constant current discharge over an available voltage range).

[0126] Referring to FIG. 10, if the peak comparison value exceeds the reference comparison value (e.g., 1.00), such as in section (B1), the value of step S620 is "Yes". If the value of step S620 is "Yes", the method may proceed to step S630. If the imbalanced degradation state between the heterogeneous active materials included in the target cell (50) and / or the degradation of the target cell (50) itself is outside the normal range, the value of step S620 may be output as "Yes".

[0127] On the other hand, if the peak comparison value is less than or equal to the reference comparison value, such as in section (A2), the value of step S620 is "No". If the value of step S620 is "No", the method may proceed to step S640.

[0128] In step S630, the diagnostic processing unit (165) may determine that the target cell (50) is abnormal. If the diagnostic unit (160) diagnoses that the target cell (50) is abnormal, in step S650, the management control unit (170) may control the charging and discharging of the target cell (50) to be limited (e.g., range of SOC and / or capacity, maximum available time, chargeable voltage, dischargeable voltage, etc.).

[0129] In step S640, the diagnostic processing unit (165) may diagnose that the target cell (50) is in a normal state. Specifically, if a peak differentiation phenomenon does not occur and only a single peak point is detected in the voltage region of interest (HV) as shown in FIG. 7, the calculation processing unit (157) may not perform an operation for determining a peak comparison value. Instead, the diagnostic processing unit (165) may set the peak comparison value to a predetermined value (e.g., 0) that is less than the reference comparison value.

[0130] For example, in section (A1) of FIG. 10, no point representing a peak comparison value is plotted, indicating that only a single peak point was detected in the voltage region of interest (HV) during the period corresponding to section (A1).

[0131] As another example, multiple points are plotted in section (A2) of FIG. 10, which means that, unlike section (A1), multiple peak points were detected in section (A2). However, since the peak comparison values ​​of all points in section (A2) are less than the reference comparison value, the diagnostic processing unit (165) can diagnose that the target cell (50) is in a normal state even in section (A2).

[0132] The information generation unit (167) may be configured to generate diagnostic information (e.g., identification information, time information determined to be abnormal, etc.) for a target cell (50) diagnosed as abnormal, and output the generated diagnostic information to a user terminal and / or a vehicle's info system. Step S660 may be substantially common to the aforementioned step S480.

[0133] Meanwhile, section (B2) illustrated in FIG. 10 corresponds to a higher cycle number than section (B1). Therefore, those skilled in the art will readily understand that the imbalanced degradation state between the active materials of the target cell (50) will be more severe in section (B2) than in section (B1).

[0134] Interval (B2) is similar to interval (A1) in that not a single point is plotted therein. However, the reason why there are no plotted points in interval (B2) may be that peak differentiation has already occurred, but the peak differentiation has intensified, such that the second peak point has shifted to a lower voltage side than the lower limit of the voltage range of interest (i.e., the reference voltage value). If the second peak point shifts to the left so that the voltage value of the second peak point becomes lower than the reference voltage value, only a single peak point (CP1) may exist within the voltage range of interest (HV), and then the peak comparison value determination operation by the diagnostic processing unit (165) is not performed, resulting in no plotted points in interval (B2). Therefore, the reason why there are no plotted points in interval (B2) is clearly distinct from the reason why there are no plotted points in interval (A1).

[0135] The diagnostic processing unit (165) may generate an unusable message for the target cell (50) when a transition event occurs from section (B1) to section (B2). The transition event may be equivalent to an event in which the voltage value of the second peak point as a characteristic point decreases below a reference voltage value. Whether the transition event occurs can be confirmed from the history data of the peak comparison value. The unusable message may be intended to notify a user or the like that charging and discharging of the target cell (50) needs to be interrupted and / or replaced with another battery cell.

[0136] The battery diagnostic device (100) can be applied to a BMS (Battery Management System). That is, the BMS can include the battery diagnostic device (100) described above. In this case, at least some of the components of the battery diagnostic device (100) can be implemented by supplementing or adding to the functions of the components included in a conventional BMS.

[0137] Additionally, the battery diagnostic device (100) may be provided in a battery pack. That is, the battery pack may include the above-described battery diagnostic device (100) and one or more battery cells, battery assemblies, or battery modules or battery cell groups.

[0138] Furthermore, the battery diagnostic device (100) may be installed in a vehicle, such as an electric vehicle or a hybrid vehicle. That is, a vehicle according to the present invention may include a battery diagnostic device according to the present invention or a battery pack according to the present invention. Furthermore, a vehicle according to the present invention may further include various other components included in the vehicle in addition to the battery diagnostic device or battery pack. For example, a vehicle according to the present invention may further include a body, a motor, a control device such as an ECU (electronic control unit), etc. in addition to the device according to the present invention.

[0139] The embodiments of the present invention described above are not implemented only through devices and methods, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation can be easily implemented by an expert in the technical field to which the present invention belongs based on the description of the embodiments described above.

[0140] Although the present invention has been described above with reference to 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 idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0141] In addition, the present invention described above is not limited to the above-described embodiments and the attached drawings, and all or part of each embodiment may be selectively combined and configured so that various modifications can be made, as those skilled in the art can make various substitutions, modifications, and changes within the scope of the technical idea of ​​the present invention.

Claims

1. A data processing unit for obtaining a differential profile representing the charge / discharge characteristics of a battery cell; When there are multiple peak points in the above differential profile, an operation unit that determines a peak comparison value based on any two of the multiple peak points, which are the first peak point and the second peak point; and A diagnostic unit that diagnoses the status of the battery cell based on the above peak comparison value; A battery diagnostic device comprising:

2. In paragraph 1, The above first peak point and second peak point are, A battery diagnostic device that indicates the charge / discharge characteristics of two active materials included in the above battery cell.

3. In paragraph 1, A management control unit that controls charging and discharging of the battery cell to be limited when the battery cell is diagnosed as abnormal; A battery diagnostic device further comprising:

4. In paragraph 1, The above operation unit, Among the above multiple peak points, one having the minimum voltage difference from the reference peak point is determined as the first peak point, A battery diagnostic device, wherein, among the plurality of peak points, another peak point having a voltage value lower than that of the first peak point and a minimum voltage difference from the first peak point is determined as the second peak point.

5. In paragraph 1, The above operation unit, A battery diagnostic device that determines the peak comparison value based on a ratio between the differential capacity value of the first peak point and the differential capacity value of the second peak point.

6. In paragraph 1, The above diagnostic section, If the above peak comparison value exceeds the reference comparison value, the battery cell is diagnosed as an abnormal cell, A battery diagnostic device that diagnoses the battery cell as normal when the peak comparison value is less than or equal to the reference comparison value.

7. In paragraph 1, The above diagnostic section, A battery diagnostic device that generates diagnostic information indicating that the battery cell is abnormal when the battery cell is diagnosed as abnormal.

8. In paragraph 1, The above diagnostic section, A battery diagnostic device that diagnoses the state of the battery cell based on the history data of the peak comparison value when a single peak point exists in the above differential profile.

9. In paragraph 8, The above diagnostic section, A battery diagnostic device that diagnoses the battery cell as abnormal if at least one previous peak comparison value is identified from the above history data.

10. In paragraph 8, The above diagnostic section, A battery diagnostic device that diagnoses the battery cell as normal when a previous peak comparison value is not confirmed from the above history data.

11. A battery pack comprising a battery diagnostic device according to any one of claims 1 to 10.

12. A vehicle including a battery diagnostic device according to any one of claims 1 to 10.

13. A step of obtaining a differential profile representing the charge / discharge characteristics of a battery cell; In the case where there are multiple peak points in the above differential profile, a step of determining a peak comparison value based on any two of the multiple peak points, that is, the first peak point and the second peak point; and A step of diagnosing the status of the battery cell based on the above peak comparison value; A battery diagnostic method comprising:

14. In paragraph 13, The step of determining the above peak comparison value is: A step of determining, among the plurality of peak points, one having a minimum voltage difference from the reference peak point as the first peak point; and A step of determining, among the plurality of peak points, another one having a voltage value lower than that of the first peak point and a minimum voltage difference from the first peak point, as the second peak point; A battery diagnostic method comprising:

15. In paragraph 13, The step of determining the above peak comparison value is: A battery diagnosis method for determining the peak comparison value based on a ratio between the differential capacity value of the first peak point and the differential capacity value of the second peak point.

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