Apparatus and method for diagnosing battery

Abstract

An apparatus for diagnosing a battery according to one embodiment of the present invention comprises: a data acquisition unit configured to acquire voltage information of a target cell and each of remaining battery cells included in a battery pack; and a processor configured to compare the voltage value of the target cell with the voltage value of the remaining battery cells in each of a plurality of preset SOC sections, determine a minimum voltage ratio of the target cell corresponding to each of the plurality of SOC sections on the basis of the comparison result, and diagnose the state of the target cell on the basis of the plurality of determined minimum voltage ratios.

Description

Battery diagnostic device and method

[0001] The present invention relates to a battery diagnostic device and method, and more specifically, to a battery diagnostic device and method for diagnosing the condition of a battery cell included in a battery pack.

[0002] This application claims priority based on Korean Application No. 10-2024-0165276 filed on November 19, 2024, and all contents disclosed in the specification of said application are incorporated into this application.

[0003]

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

[0005] Currently commercialized batteries include nickel-cadmium, nickel-hydrogen, nickel-zinc, and lithium batteries. Among these, lithium batteries are gaining attention for their advantages, such as the ability to freely charge and discharge with almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density.

[0006] Voltage deviations between battery cells within a battery pack are continuously controlled by the Battery Management System (BMS) during charging, discharging, and idle states. Since the BMS is designed to maintain overall voltage balance within the battery pack by balancing voltages between battery cells, even if a problem exists in a battery cell, the resulting voltage deviation may not be significantly apparent.

[0007] In particular, if a voltage deviation between battery cells is below a predetermined value, such deviation can be resolved through voltage balancing by the BMS; however, if the voltage deviation exceeds a predetermined value, it is difficult to completely resolve it through voltage balancing alone, and voltage imbalance between battery cells may persist. A voltage deviation exceeding a predetermined value is an abnormal condition that is not corrected by voltage balancing and can cause the battery cells to fail to function normally. Therefore, it is important to diagnose the condition early before the voltage deviation increases.

[0008] Conventionally, battery condition has been diagnosed primarily by monitoring voltage deviations. However, conventional methods have limitations in that they can only diagnose abnormal conditions after the voltage deviation exceeds a certain level, making early diagnosis difficult. Since it is highly likely that serious problems have already occurred in the battery cells by the time the voltage deviation has accumulated and become sufficiently large, there is a need for technology capable of diagnosing the condition of battery cells even when the voltage deviation is relatively small.

[0009]

[0010] The present invention was devised to solve the above-mentioned problems and aims to provide a battery diagnostic device and method capable of improving the safety and reliability of a battery pack by diagnosing the condition of a battery cell even when the voltage deviation is relatively small, by utilizing the minimum voltage ratio calculated through voltage comparison between battery cells.

[0011] Other objects and advantages of the present invention may be understood from the following description and will become more clearly apparent from 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.

[0012]

[0013] A battery diagnostic device according to one aspect of the present invention may include: a data acquisition unit configured to acquire voltage information for each of a plurality of battery cells included in a battery pack; and a processor configured to determine a target cell and a remaining battery cell among the plurality of battery cells, compare the voltage value of the target cell with the voltage value of the remaining battery cell in each of a plurality of preset SOC intervals, determine the minimum voltage ratio of the target cell corresponding to each of the plurality of SOC intervals based on the comparison result, and diagnose the state of the target cell based on the determined plurality of minimum voltage ratios.

[0014] The above processor may be configured to determine the minimum voltage time of the target cell for each of the plurality of SOC intervals based on the comparison result.

[0015] The above processor may be configured to determine the plurality of minimum voltage ratios based on the reference time of each of the plurality of SOC intervals and the determined plurality of minimum voltage times.

[0016] The above processor may be configured to determine the minimum voltage ratio according to the ratio of the minimum voltage time to the reference time for each of the plurality of SOC intervals.

[0017] The above processor may be configured to diagnose the state of the target cell as a low voltage state if the plurality of minimum voltage ratios is greater than or equal to a preset first threshold.

[0018] The above processor may be configured to divide the plurality of SOC sections into one or more upper SOC sections and one or more lower SOC sections.

[0019] The processor may be configured to compare the minimum voltage ratio corresponding to each of the one or more upper SOC sections and the one or more lower SOC sections with at least one of a second threshold value preset to correspond to a high capacity state and a third threshold value preset to correspond to a low capacity state.

[0020] The above processor may be configured to diagnose the state of the target cell based on the comparison result.

[0021] The processor may be configured to diagnose the state of the target cell as the high-capacity state if the minimum voltage ratio corresponding to each of the one or more upper SOC sections is greater than or equal to the second threshold, and the minimum voltage ratio corresponding to each of the one or more lower SOC sections is less than the second threshold.

[0022] The processor may be configured to diagnose the state of the target cell as the low-capacity state if the minimum voltage ratio corresponding to each of the one or more upper SOC sections is less than the third threshold and the minimum voltage ratio corresponding to each of the one or more lower SOC sections is greater than or equal to the third threshold.

[0023] The above processor may be configured to divide the entire SOC range into multiple SOC ranges based on a differential profile representing the correspondence between the differential voltage and SOC of the battery pack.

[0024] The processor may be configured to divide the plurality of SOC sections into one or more upper SOC sections and one or more lower SOC sections based on a first reference peak and a second reference peak included in the differential profile.

[0025] The above third threshold value may be pre-set to a value less than the above second threshold value.

[0026] The above processor may be configured to determine a plurality of peaks from a differential profile representing the corresponding relationship between the differential voltage and SOC of the battery pack.

[0027] The above processor may be configured to divide the entire SOC range into the plurality of SOC ranges based on the plurality of peak SOCs.

[0028] A battery pack according to another aspect of the present invention may include the battery diagnostic device.

[0029] An automobile according to another aspect of the present invention may include the battery diagnostic device.

[0030] A server according to another aspect of the present invention may include the battery diagnostic device.

[0031] A battery diagnostic method according to another aspect of the present invention may include: a data acquisition step of acquiring voltage information for each of a plurality of battery cells included in a battery pack; a target cell determination step of determining a target cell and a remaining battery cell among the plurality of battery cells; a comparison step of comparing the voltage value of the target cell with the voltage value of the remaining battery cell in each of a plurality of preset SOC intervals; a minimum voltage ratio determination step of determining the minimum voltage ratio of the target cell corresponding to each of the plurality of SOC intervals based on the comparison result; and a diagnostic step of diagnosing the state of the target cell based on the determined plurality of minimum voltage ratios.

[0032] A computer-readable recording medium according to another aspect of the present invention may be a computer-readable recording medium having a program recorded thereon for performing the battery diagnostic method on a computer.

[0033]

[0034] According to one aspect of the present invention, the battery diagnostic device has the advantage of being able to diagnose the condition of a plurality of battery cells included in a battery pack from various perspectives.

[0035] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0036]

[0037] The following drawings attached to this specification serve to further enhance understanding of the technical concept of the invention in conjunction with the detailed description of the invention set forth below; therefore, the invention should not be interpreted as being limited only to the matters described in such drawings.

[0038] FIG. 1 is a schematic diagram illustrating a battery diagnostic device according to one embodiment of the present invention.

[0039] Figure 2 is a diagram illustrating the minimum voltage time, reference time, and minimum voltage ratio of the target cell for each SOC interval.

[0040] Figure 3 is a diagram illustrating the minimum voltage time, reference time, and minimum voltage ratio of a plurality of battery cells for the first section.

[0041] Figure 4 is a schematic diagram illustrating an example of a differential profile.

[0042] FIG. 5 is a schematic diagram illustrating a battery pack according to another embodiment of the present invention.

[0043] FIG. 6 is a schematic drawing illustrating an automobile according to another embodiment of the present invention.

[0044] FIG. 7 is a schematic diagram illustrating a server according to another embodiment of the present invention.

[0045] FIG. 8 is a schematic diagram illustrating a battery diagnostic method according to another embodiment of the present invention.

[0046]

[0047] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0048] 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.

[0049] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0050] Terms including ordinal numbers, such as first, second, etc., are used for the purpose of distinguishing one of the various components from the rest, and are not used to limit the components by such terms.

[0051] Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0052] Additionally, throughout the specification, when it is said that a part is "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other components in between.

[0053]

[0054] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0055] FIG. 1 is a schematic diagram illustrating a battery diagnostic device (100) according to one embodiment of the present invention.

[0056] Referring to FIG. 1, the battery diagnostic device (100) may include a data acquisition unit (110) and a processor (120). The battery diagnostic device (100) may further include a storage unit (130).

[0057] The data acquisition unit (110) may be configured to acquire voltage information for each of the plurality of battery cells included in the battery pack.

[0058] Here, a battery cell refers to a single, independent cell that is physically separable and equipped with a negative terminal and a positive terminal. For example, a lithium-ion battery or a lithium-polymer battery may be considered a battery cell. Additionally, depending on its shape, the battery cell may be configured as a cylindrical type, a prismatic type, or a pouch type.

[0059] In one embodiment, the data acquisition unit (110) can directly measure the voltage of each of the plurality of battery cells included in the battery pack. Specifically, the data acquisition unit (110) can measure the positive voltage and the negative voltage through a pair of voltage sensing lines connected to the positive and negative electrodes of the battery cells, respectively. Then, the data acquisition unit (110) can measure the voltage across both ends of the battery cell based on the voltage difference between the measured positive voltage and the negative voltage. That is, the data acquisition unit (110) can obtain voltage information by directly measuring the voltage of the battery cell. In addition, the data acquisition unit (110) can obtain voltage information by measuring the voltage of the battery cell at regular intervals or irregularly.

[0060] In another embodiment, the data acquisition unit (110) can receive voltage information from the outside. That is, the data acquisition unit (110) can receive voltage information from the outside by being connected via wired and / or wireless so as to be able to communicate with the outside. For example, the data acquisition unit (110) can receive voltage information from the outside using CAN (Controller Area Network) communication or CAN-FD (CAN with Flexible Data rate) communication. As another example, the data acquisition unit (110) can receive voltage information from the outside using Zigbee, Bluetooth, WIFI, or a mobile communication network. Of course, as long as it supports communication between the data acquisition unit (110) and the outside, the type of communication protocol is not particularly limited.

[0061] The data acquisition unit (110) may be connected via wired and / or wireless means to communicate with the processor (120). The data acquisition unit (110) may transmit acquired voltage information to the processor (120). The processor (120) may receive voltage information from the data acquisition unit (110).

[0062] The processor (120) can be configured to determine the target cell and the remaining battery cells among a plurality of battery cells.

[0063] Here, the target cell may refer to a specific battery cell among multiple battery cells within a battery pack that is the subject of diagnosis. Ideally, all cells within a battery pack should maintain identical performance; however, each cell may exhibit differences in electrical characteristics over time due to factors such as minute variations in the manufacturing process and the operating environment. Since these differences in characteristics can lead to degradation of the battery pack's overall performance, safety issues, and a shortened lifespan, it is recognized that it is necessary to designate a specific cell as a target cell to monitor and diagnose its condition separately.

[0064] Specifically, the processor (120) can sequentially determine each of the plurality of battery cells as a target cell and diagnose the state of the plurality of battery cells. For example, the processor (120) can determine one of the plurality of battery cells as a target cell and diagnose the state of the target cell. Subsequently, until the state of all the plurality of battery cells is diagnosed, the processor (120) can determine one of the battery cells that has not been determined as a target cell as a target cell and diagnose the state of the target cell.

[0065] The processor (120) may be configured to compare the voltage value of a target cell with the voltage value of the remaining battery cells in each of the preset multiple SOC intervals.

[0066] Here, an SOC section may refer to the entire SOC range being divided into multiple sections according to predetermined criteria. That is, the entire SOC range can be divided into several SOC sections according to predetermined criteria.

[0067] In one embodiment, the entire SOC range may be divided equally at regular intervals to set the SOC sections. For example, the SOC 0~100% range may be divided equally at intervals of 25% to form the SOC 0~25% section, SOC 25~50% section, SOC 50~75% section, and SOC 75~100% section.

[0068] In another embodiment, a plurality of SOC ranges may be set based on the differential profile of the battery pack. For example, the SOC ranges may be set based on the position of a peak included in the differential profile. For convenience of explanation, a specific embodiment in which the SOC ranges are set based on the differential profile will be described later.

[0069] Specifically, the processor (120) can compare the voltage value of the target cell with the voltage value of each of the remaining battery cells. That is, the processor (120) can determine whether the voltage of the target cell is higher or lower than the voltage of the remaining battery cells.

[0070] For example, if the battery pack includes four battery cells (first to fourth cells), the processor (120) can individually compare the voltage value of the target cell (first cell) with the voltage values ​​of the remaining battery cells (second cell, third cell and fourth cell).

[0071] Specifically, voltage comparison between the target cell and the remaining battery cells can be performed for each SOC interval. That is, the processor (120) can compare the voltage between the target cell and the remaining battery cells in each SOC interval.

[0072] For example, if the SOC section is divided into four sections, the processor (120) compares the voltage value of the target cell in the first section with the voltage values ​​of the remaining battery cells, and can repeat the same comparison process for the second, third, and fourth sections.

[0073] Specifically, the processor (120) can compare the voltage value of the target cell measured at the same time with the voltage value of each of the remaining battery cells.

[0074] For example, if the voltage is measured n times in a certain SOC interval, the processor (120) can compare the voltage value of the target cell measured at the same time with the voltage value of each of the remaining battery cells a total of n times.

[0075] The processor (120) may be configured to determine the minimum voltage ratio of a target cell corresponding to each of a plurality of SOC intervals based on the comparison result.

[0076] The minimum voltage ratio refers to the time or frequency during which the voltage of the target cell is relatively lower than the voltage of the remaining battery cells within each SOC interval.

[0077] That is, the minimum voltage ratio is a value representing how often the target cell exhibits a relatively low voltage state compared to the remaining battery cells for each SOC interval, and can be calculated based on the time or number of times the target cell is determined to be the minimum voltage cell in each SOC interval.

[0078] For example, if the voltage is measured n times in a certain SOC interval and the target cell is determined to be the m minimum voltage cell, the processor (120) can calculate the minimum voltage ratio of the target cell as m÷n.

[0079] For example, for the first section, the processor (120) can calculate the minimum voltage ratio of the target cell for the first section by comparing the voltage value of the target cell (the first cell) with the voltage values ​​of the second cell, the third cell, and the fourth cell. In this way, the processor (120) can determine the minimum voltage ratio of the target cell for the second section, the third section, and the fourth section, respectively.

[0080] The processor (120) may be configured to diagnose the state of the target cell based on a determined plurality of minimum voltage ratios.

[0081] Specifically, the processor (120) can diagnose the state of the target cell as normal or abnormal based on the minimum voltage ratio for each section calculated for the target cell. Here, a normal state means that the state of the target cell is similar to the state of the remaining battery cells. Conversely, an abnormal state means that the state of the target cell differs from the state of the remaining battery cells.

[0082] For example, target cells diagnosed as being in an abnormal state may be low-voltage cells, high-capacity cells, or low-capacity cells. A low-voltage cell refers to a battery cell that is unable to maintain a normal voltage. For instance, low voltage can primarily be caused by internal cell issues, such as micro short circuits. Because a small amount of current continuously flows internally due to micro short circuits, low-voltage cells may exhibit lower voltage compared to other battery cells. Due to these characteristics, low-voltage cells have a high self-discharge rate and tend to show a rapid decrease in voltage even when not in use.

[0083] A high-capacity cell refers to a battery cell with a relatively larger capacity compared to the remaining cells. In other words, because high-capacity cells possess a larger capacity capable of storing more energy than the other cells, their voltage does not increase rapidly during charging compared to the other cells, nor does it decrease rapidly during discharging. Meanwhile, it should be noted that while high capacity cannot be considered a defect of the battery cell, the condition of the high-capacity cell is classified as abnormal to maintain balance with the other cells.

[0084] Low-capacity cells refer to battery cells with a relatively smaller capacity compared to the rest of the battery cells. Specifically, low-capacity cells tend to show a faster and more rapid voltage increase during the charging process compared to the rest of the battery cells. Additionally, because the voltage of low-capacity cells rises more rapidly than the rest of the battery cells even within the upper SOC range, they reach full charge much sooner. Furthermore, low-capacity cells tend to show a faster and more rapid voltage decrease during the discharging process compared to the rest of the battery cells.

[0085] A battery diagnostic device (100) according to one embodiment of the present invention has the advantage of being able to detect minute voltage changes occurring in a specific range early by comparing the voltage between a target cell and other cells according to SOC ranges, and to improve the safety and reliability of the battery pack by diagnosing the condition of the battery cell from when the voltage deviation is relatively small by utilizing the minimum voltage ratio calculated through voltage comparison.

[0086]

[0087] Meanwhile, the data acquisition unit (110) and / or processor (120) provided in the battery diagnostic device (100) may optionally include a processor, an ASIC (application-specific integrated circuit), another chipset, a logic circuit, a register, a communication modem, a data processing device, etc., known in the art to execute various control logics performed in the present invention. Additionally, when the control logic is implemented in software, the data acquisition unit (110) and / or processor (120) may be implemented as a set of program modules. In this case, the program modules may be stored in memory and executed by the data acquisition unit (110) and / or processor (120). The memory may be located inside or outside the data acquisition unit (110) and / or processor (120) and may be connected to the data acquisition unit (110) and / or processor (120) by various well-known means.

[0088] Additionally, the battery diagnostic device (100) may further include a storage unit (130). The storage unit (130) may store data or programs necessary for each component of the battery diagnostic device (100) to perform operations and functions, or data generated during the process of performing operations and functions. The storage unit (130) is not limited in its type as long as it is a known information storage means known to be able to record, erase, update, and read data. As an example, the information storage means may include RAM, flash memory, RM, EEPRM, registers, etc. Additionally, the storage unit (130) may store program codes in which processes executable by the data acquisition unit (110) and / or the processor (120) are defined.

[0089] Specifically, the storage unit (130) can store information necessary for the processor (120) to diagnose the state of the battery. For example, the storage unit (130) can store voltage information, a differential profile, a first threshold value, a second threshold value, and a third threshold value. And, the processor (120) can access the storage unit (130) to obtain information necessary for the processor (120) to diagnose the state of the battery. For example, voltage information obtained by the data acquisition unit (110) is stored in the storage unit (130), and the processor (120) can access the storage unit (130) to obtain the stored voltage information.

[0090]

[0091] Below, specific embodiments for determining the minimum voltage ratio are described.

[0092] The processor (120) may be configured to determine the minimum voltage time of the target cell for each of the multiple SOC intervals based on the comparison result.

[0093] Here, the minimum voltage time refers to the time during which the target cell maintains a relatively lower voltage state compared to the remaining battery cells within each SOC range. In other words, the minimum voltage time is a quantitative indicator representing how long the voltage of the target cell remains lower than that of the other battery cells.

[0094] In one embodiment, when the voltages of the cells are measured periodically, the processor (120) may determine that the target cell corresponds to a minimum voltage state at each measurement point if the voltage of the target cell is lower than the voltage of the other cells. The processor (120) may accumulate and count the number of times the target cell corresponds to a minimum voltage state and calculate the minimum voltage time by multiplying the accumulated count by the voltage measurement interval. For example, if the voltage measurement interval is 1 second and the number of times the target cell corresponds to a minimum voltage state is counted as 30 times, the minimum voltage time of the corresponding SOC interval may be determined to be 30 seconds.

[0095] The processor (120) may be configured to determine a plurality of minimum voltage ratios based on a reference time for each of a plurality of SOC intervals and a determined plurality of minimum voltage times.

[0096] Specifically, the processor (120) may be configured to determine the minimum voltage ratio for each of the multiple SOC intervals according to the ratio of the minimum voltage time to the reference time.

[0097] That is, the processor (120) can determine the minimum voltage ratio by calculating the ratio of the minimum voltage time calculated in each SOC interval to the reference time.

[0098] Here, the reference time may refer to the total time spent in each SOC section.

[0099] Specifically, since the time required for charging or discharging may differ in each SOC range, the reference time may vary for each SOC range. By reflecting these differences and normalizing through the reference time, the voltage characteristics of each SOC range can be consistently compared.

[0100] For example, the reference time for a specific SOC range can be defined as the time required to charge that range. As another example, the reference time for a specific SOC range can be defined as the time required to discharge that range.

[0101] For example, the minimum voltage ratio can be calculated by dividing the minimum voltage time by the reference time.

[0102] The minimum voltage ratio represents the ratio of the time the target cell maintains a relatively low voltage state within each SOC interval. In other words, the minimum voltage ratio quantitatively indicates the voltage state of the target cell.

[0103] Figure 2 is a diagram illustrating the minimum voltage time, reference time, and minimum voltage ratio of the target cell for each SOC interval.

[0104] In the embodiment of FIG. 2, when the minimum voltage time of the target cell in the first section is t11 and the reference time is tr1, the minimum voltage ratio of the first section is k11. Here, k11 can be calculated according to the formula “t11÷tr1”. When the minimum voltage time of the target cell in the second section is t12 and the reference time is tr2, the minimum voltage ratio of the second section is k12. Here, k12 can be calculated according to the formula “t12÷tr2”. When the minimum voltage time of the target cell in the third section is t13 and the reference time is tr3, the minimum voltage ratio of the third section is k13. Here, k13 can be calculated according to the formula “t13÷tr3”. When the minimum voltage time of the target cell in the fourth section is t14 and the reference time is tr4, the minimum voltage ratio of the fourth section is k14. Here, k14 can be calculated according to the formula “t14÷tr4”.

[0105] Figure 3 is a diagram illustrating the minimum voltage time, reference time, and minimum voltage ratio of a plurality of battery cells for the first section.

[0106] In the embodiment of FIG. 3, when the minimum voltage time of the first cell (target cell) is t11 and the reference time is tr1, the minimum voltage ratio of the first cell is k11. Here, k11 can be calculated according to the formula "t11÷tr1". When the minimum voltage time of the second cell is t21 and the reference time is tr1, the minimum voltage ratio of the first cell is k21. Here, k21 can be calculated according to the formula "t21÷tr1". When the minimum voltage time of the third cell is t31 and the reference time is tr1, the minimum voltage ratio of the first cell is k31. Here, k31 can be calculated according to the formula "t31÷tr1". When the minimum voltage time of the fourth cell is t41 and the reference time is tr1, the minimum voltage ratio of the first cell is k41. Here, k41 can be calculated according to the formula "t41÷tr1".

[0107] Figure 3 is a table showing values ​​for the first section, so it can be confirmed that the reference time is the same as tr1 as the elapsed time of the first section.

[0108] A battery diagnostic device (100) according to one embodiment of the present invention has the advantage of being able to accurately monitor changes in the state of a battery cell and improve the reliability of the diagnosis by calculating the minimum voltage ratio for each SOC range and each battery cell, and quantitatively comparing the voltage characteristics of a target cell with other battery cells.

[0109]

[0110] Hereinafter, a specific embodiment is described in which a processor (120) diagnoses whether a target cell is a low-voltage cell based on the minimum voltage ratio of the target cell.

[0111] The processor (120) may be configured to compare the minimum voltage ratio of the target cell calculated in each SOC interval with a preset first threshold.

[0112] Specifically, the processor (120) can individually compare the minimum voltage ratio of the target cell for each of the multiple SOC intervals with the first threshold value.

[0113] For example, if a plurality of minimum voltage ratios calculated for a target cell are all greater than or equal to a first threshold, the processor (120) may diagnose the state of the target cell as a low-voltage cell. As another example, if at least one of a plurality of minimum voltage ratios calculated for a target cell is less than the first threshold, the processor (120) may not diagnose the state of the target cell as a low-voltage cell.

[0114] In the embodiment of FIG. 2, if the plurality of minimum voltage ratios (k11, k12, k13 and k14) of the target cell calculated in the first to fourth intervals are all greater than or equal to the first threshold value, the processor (120) can diagnose the state of the target cell as a low-voltage cell. Conversely, if at least one of the plurality of minimum voltage ratios (k11, k12, k13 and k14) is less than the first threshold value, the processor (120) may not diagnose the state of the target cell as a low-voltage cell.

[0115] In the present invention, when diagnosing the voltage characteristics of a target cell, an absolute standard (a first threshold value) is applied rather than a relative comparison with other cells. Here, the first threshold value can be set based on theoretical analysis and / or experimental data. Furthermore, not only the target cell but also other cells within the battery pack can be diagnosed individually according to the same absolute standard. Accordingly, multiple cells within the battery pack can be diagnosed as low-voltage cells.

[0116] A battery diagnostic device (100) according to one embodiment of the present invention can diagnose the low voltage state of a target cell more accurately and early by monitoring whether the target cell continues to be in a low voltage state in all SOC sections based on the minimum voltage ratio calculated in each SOC section.

[0117]

[0118] Hereinafter, a specific embodiment is described in which a processor (120) diagnoses whether a target cell is a high-capacity cell or a low-capacity cell based on the minimum voltage ratio of the target cell.

[0119] The processor (120) may be configured to divide a plurality of SOC sections into one or more upper SOC sections and one or more lower SOC sections. The upper SOC section refers to a section with a high SOC value, and the lower SOC section refers to a section with a low SOC value.

[0120] In the embodiment of FIG. 2, the first section may be set to represent an SOC range of 0 to 25%, the second section to represent an SOC range of 25 to 50%, the third section to represent an SOC range of 50 to 75%, and the fourth section to represent an SOC range of 75 to 100%. The first and second sections may be divided into lower SOC ranges, and the third and fourth sections may be divided into upper SOC ranges.

[0121] The processor (120) can diagnose whether the target cell is a high-capacity cell by comparing the minimum voltage ratio corresponding to each of one or more upper SOC sections and one or more lower SOC sections with a second threshold value pre-set to correspond to a high-capacity cell. Additionally, the processor (120) can diagnose whether the target cell is a low-capacity cell by comparing the minimum voltage ratio corresponding to each of one or more upper SOC sections and one or more lower SOC sections with a third threshold value pre-set to correspond to a low-capacity cell.

[0122] Specifically, the processor (120) can compare the magnitude between a minimum voltage ratio corresponding to each of one or more upper SOC sections and one or more lower SOC sections and a second threshold. Additionally, the processor (120) can compare the magnitude between a minimum voltage ratio corresponding to each of one or more upper SOC sections and one or more lower SOC sections and a third threshold.

[0123] Here, the second threshold value is a reference value for diagnosing the target cell as a high-capacity cell, and the third threshold value can be set as a reference value for diagnosing the target cell as a low-capacity cell.

[0124] Preferably, the third threshold can be preset to a value less than the second threshold. Low-capacity cells can have a greater impact on the performance and safety of the battery pack compared to high-capacity cells. For example, if the discharge end point of the battery pack is set to match the voltage of the low-capacity cells, the discharge capacity of the entire battery pack may be reduced. As another example, if the low-capacity cells are charged to match the voltage of other battery cells, there is a risk that the low-capacity cells will be overcharged. Therefore, since the diagnostic criteria for low-capacity cells need to be set more strictly than those for high-capacity cells, the third threshold can be set to a value less than the second threshold.

[0125] The processor (120) can be configured to diagnose the state of the target cell based on the comparison result.

[0126] Specifically, if the minimum voltage ratio corresponding to each of one or more upper SOC sections is greater than or equal to the second threshold, and the minimum voltage ratio corresponding to each of one or more lower SOC sections is less than the second threshold, the processor (120) may be configured to diagnose the state of the target cell as a high-capacity cell.

[0127] In the embodiment of FIG. 2, if the minimum voltage ratio of the first and second sections is less than the second threshold and the minimum voltage ratio of the third and fourth sections is greater than or equal to the second threshold, the processor (120) can diagnose the state of the target cell as a high-capacity cell.

[0128] Specifically, if the minimum voltage ratio corresponding to each of one or more upper SOC sections is less than the third threshold and the minimum voltage ratio corresponding to each of one or more lower SOC sections is greater than or equal to the third threshold, the processor (120) may be configured to diagnose the state of the target cell as a low-capacity cell.

[0129] In the embodiment of FIG. 2, if the minimum voltage ratio of the first and second sections is greater than or equal to the third threshold and the minimum voltage ratio of the third and fourth sections is less than the third threshold, the processor (120) can diagnose the state of the target cell as a low-capacity cell.

[0130] A battery diagnostic device (100) according to one embodiment of the present invention can diagnose high-capacity cells and low-capacity cells more accurately and early based on the minimum voltage ratio calculated in one or more upper SOC sections and one or more lower SOC sections.

[0131]

[0132] Hereinafter, a specific embodiment in which the processor (120) sets the SOC range based on the differential profile of the battery pack is described.

[0133] Figure 4 is a schematic diagram illustrating an example of a differential profile of a battery pack. In Figure 4, the horizontal axis represents the SOC (%) of the battery pack, and the vertical axis represents the differential voltage (dV / dSOC) of the battery pack. Here, the differential voltage (dV / dSOC) is the value obtained by differentiating the voltage (V) of the battery pack with respect to the SOC of the battery pack. That is, the differential voltage (dV / dSOC) represents the instantaneous rate of change of voltage with respect to the SOC of the battery pack.

[0134] In one embodiment, the data acquisition unit (110) can measure the voltage and current of the battery pack. The data acquisition unit (110) can transmit the voltage information and current information of the battery pack to the processor (120). The processor (120) can estimate the SOC of the battery pack based on the received voltage information and / or current information of the battery pack. The processor (120) can generate a differential profile of the battery pack based on the voltage and SOC of the battery pack.

[0135] In another embodiment, the data acquisition unit (110) can receive a differential profile from the outside. That is, the data acquisition unit (110) can receive a differential profile from the outside by being connected via wired and / or wireless so as to be able to communicate with the outside. Then, the data acquisition unit (110) can transmit the acquired differential profile to the processor (120). The processor (120) can receive the differential profile from the data acquisition unit (110).

[0136] In another embodiment, the processor (120) may be connected via wired and / or wireless so as to communicate with the outside and may directly receive a differential profile from the outside.

[0137] The processor (120) can divide the entire SOC section into multiple SOC sections based on the differential profile.

[0138] Specifically, the processor (120) may be configured to determine a plurality of peaks from a differential profile representing the corresponding relationship between the differential voltage and SOC of the battery.

[0139] Here, peaks can refer to maximum and minimum points of the derivative profile. Peaks can refer to points in the derivative profile where the instantaneous rate of change is zero. That is, based on the peak, the instantaneous rate of change of the derivative profile can transition from increasing to decreasing or from decreasing to increasing.

[0140] For example, in the embodiment of FIG. 4, the processor (120) can determine the first peak (p1), the second peak (p2), the third peak (p3), the fourth peak (p4), the fifth peak (p5), the sixth peak (p6), the seventh peak (p7), the eighth peak (p8), the ninth peak (p9), and the tenth peak (p10) as peaks in the differential profile.

[0141] The processor (120) may be configured to divide the entire SOC section into multiple SOC sections based on multiple peak SOCs.

[0142] Specifically, the processor (120) can set the SOC intervals such that each SOC interval includes at least one peak.

[0143] For example, in the embodiment of FIG. 4, the SOC sections may be set such that the first section includes the first to fourth peaks (p1 to p4), the second section includes the fifth peak (p5), the third section includes the sixth peak (p6), and the fourth section includes the seventh to tenth peaks (p7 to p10).

[0144] However, it should be noted that the method of dividing the entire SOC range into multiple SOC ranges based on the SOC of the peaks is not limited to examples and can be set in various ways. That is, if at least one peak is included, it can be divided into one SOC range. For example, in the embodiment of FIG. 4, the entire SOC range may be divided into 10 SOC ranges each including the first to tenth peaks (p1 to p10).

[0145] A battery diagnostic device (100) according to one embodiment of the present invention has the advantage of being able to diagnose the condition of a battery more accurately and early by using a peak position on a differential profile as a criterion for setting the SOC range, thereby reflecting the voltage characteristics of the battery cell.

[0146]

[0147] Hereinafter, a specific embodiment is described in which a plurality of SOC sections are divided into one or more upper SOC sections and one or more lower SOC sections.

[0148] The processor (120) may be configured to divide a plurality of SOC sections into one or more upper SOC sections and one or more lower SOC sections based on a first reference peak (pr1) and a second reference peak (pr2) included in the differential profile.

[0149] The first reference peak (pr1) may refer to the minimum point with the smallest differential voltage among the remaining minimum points of the differential profile, excluding the minimum point where the SOC is minimum or maximum.

[0150] For example, in the embodiment of FIG. 4, among the minimum points (p1, p3, p5, p7 and p9) of the differential profile, excluding the minimum point (p1 and p9) where the SOC is minimum or maximum, the minimum point (p5) with the smallest differential voltage among the remaining minimum points may represent the first reference peak (pr1).

[0151] The second reference peak (pr2) may refer to the maximum point with the smallest SOC among the maximum points included in the SOC range greater than or equal to the SOC of the first reference peak (pr1).

[0152] For example, in the embodiment of FIG. 4, among the maximum points (p6, p8 and p10) included in the SOC range greater than or equal to the SOC of the first reference peak (pr1), the maximum point (p6) with the smallest SOC may represent the second reference peak (pr2).

[0153] The processor (120) may determine the SOC section including a first reference peak (pr1) and the SOC section including an SOC smaller than the first reference peak (pr1) as the lower SOC section. The processor (120) may determine the SOC section including a second reference peak (pr2) and the SOC section including an SOC larger than the second reference peak (pr2) as the upper SOC section.

[0154] In the embodiment of FIG. 4, the SOC section containing the first reference peak (pr1) is the second section, and the SOC section containing the second reference peak (pr2) is the third section. Accordingly, among the plurality of SOC sections, the processor can classify the first and second sections as lower SOC sections, and the third and fourth sections as upper SOC sections.

[0155] A battery diagnostic device (100) according to one embodiment of the present invention has the advantage of being able to analyze each area and diagnose the condition of the battery more accurately by dividing the entire SOC section into upper and lower sections.

[0156]

[0157] The battery diagnostic device (100) can be configured to set usage conditions based on the condition diagnosis result for the target cell.

[0158] For example, if the state of the target cell is diagnosed as normal, the processor (120) may maintain the existing usage conditions. As another example, if the state of the target cell is diagnosed as abnormal, the processor (120) may change the existing usage conditions or perform balancing to resolve the imbalance between battery cells. Usage conditions may include a maximum charge / discharge rate, a charge end voltage, or a discharge end voltage.

[0159] Meanwhile, regarding specific embodiments for setting the usage conditions of a target cell or battery pack, it goes without saying that various methods easily applicable by a person skilled in the art to which the present invention pertains can be used.

[0160] A battery diagnostic device (100) according to one embodiment of the present invention can mitigate performance degradation of a battery pack and improve lifespan and stability by appropriately controlling usage conditions in consideration of the condition diagnosis results for a target cell.

[0161]

[0162] The battery diagnostic device (100) according to the present invention may be applied to a Battery Management System (BMS). That is, the BMS according to the present invention may include the battery diagnostic device (100) described above. In this configuration, at least some of the components of the battery diagnostic device (100) may be implemented by supplementing or adding the functions of the components included in a conventional BMS. For example, the data acquisition unit (110) and the processor (120) of the battery diagnostic device (100) may be implemented as components of the BMS.

[0163]

[0164] The battery diagnostic device (100) according to the present invention may be provided in a battery pack (10). That is, the battery pack (10) according to the present invention may include the battery diagnostic device (100) described above and a battery array (11). Here, the battery array (11) may include a plurality of battery cells. In addition, the battery pack (10) may further include electrical components (relays, fuses, etc.) and a case, etc.

[0165] The positive terminal of the battery array (11) can be connected to the positive terminal (P+) of the battery pack (10), and the negative terminal of the battery array (11) can be connected to the negative terminal (P-) of the battery pack (10).

[0166] The measuring unit (12) can measure the voltage of each of the plurality of battery cells included in the battery array (11). Specifically, sensing lines can be connected to each of the positive terminal and the negative terminal of the battery cell. The measuring unit (12) can measure the voltage of the battery cell based on the voltage measured at each of the sensing lines. In addition, the measuring unit (12) can measure the voltage of the battery pack (10) through the connected sensing lines.

[0167] Additionally, the measuring unit (12) may be connected to a current measuring unit (A). For example, the current measuring unit (A) may be an ammeter or a shunt resistor capable of measuring the charging current and discharging current of the battery array (11). The measuring unit (12) may measure the charging current of the battery array (11) to calculate the charging amount. Furthermore, the measuring unit (12) may measure the discharging current of the battery array (11) to calculate the discharging amount.

[0168] The battery diagnostic device (100) can be connected via wired and / or wireless means to communicate with the measurement unit (12). The data acquisition unit (110) can receive voltage and / or current information of the battery array (11) from the measurement unit (12).

[0169]

[0170] FIG. 6 is a schematic drawing of a vehicle (1) according to another embodiment of the present invention.

[0171] Referring to FIG. 6, the battery pack (10) of FIG. 5 may be included in a vehicle (1), such as an electric vehicle (EV) or a hybrid vehicle (HV). The battery pack (10) can drive the vehicle (1) by supplying power to a motor through an inverter provided in the vehicle (1). Here, the battery pack (10) may include a battery diagnostic device (100). In this case, the battery diagnostic device (100) may be an on-board device included in the vehicle (1).

[0172]

[0173] FIG. 7 is a schematic diagram illustrating a server (2) according to another embodiment of the present invention.

[0174] Referring to FIG. 7, the battery diagnostic device (100) according to the present invention may be provided in a server (2). The server (2) can diagnose the condition of the battery cell by providing high-performance computing resources and data storage functions.

[0175] A battery diagnostic device (100) equipped in a server (2) can individually acquire voltage information from a plurality of BMSs (3), analyze it in real time, and continuously monitor the status of battery cells for each battery pack. Specifically, the battery diagnostic device (100) running on the server (2) can determine a minimum voltage ratio corresponding to each of a plurality of SOC ranges based on voltage information. In addition, the battery diagnostic device (100) running on the server (2) can diagnose the status of the battery cells based on the minimum voltage ratio. Furthermore, the battery diagnostic device (100) running on the server (2) can divide the entire SOC range into a plurality of SOC ranges, one or more upper SOC ranges, and one or more lower SOC ranges.

[0176] The battery diagnostic device (100) provided in the server (2) can be connected via wired and / or wireless means to communicate with a plurality of BMS (3) and / or user terminals (4), etc. Additionally, the server (2) can perform integrated management of a battery system including a plurality of battery packs.

[0177] The server (2) is linked with the BMS (3) and can transmit the diagnosis results regarding the status of the battery cells included in the battery pack to the corresponding BMS (3) in real time. Alternatively, if the status of at least one battery cell included in the battery pack is diagnosed as a low-voltage cell, a high-capacity cell, or a low-capacity cell, the server (2) can transmit a warning or control signal to the corresponding BMS (3).

[0178] The server (2) can be linked with the user terminal (4) to allow the user to remotely monitor the status of the battery pack. By connecting to the server (2) using a dedicated application, the user can check the status of the battery pack and the multiple battery cells included in the battery pack in real time.

[0179] By using the battery diagnostic device (100) provided in the server (2), the performance of the battery system can be optimized and safety can be increased.

[0180]

[0181] FIG. 8 is a schematic diagram illustrating a battery diagnostic method according to another embodiment of the present invention.

[0182] Each step of the battery diagnostic method can be performed by a battery diagnostic device (100). For convenience of explanation, details that overlap with previously described content will be omitted or briefly explained below.

[0183] Referring to FIG. 8, the battery diagnostic method may include a data acquisition step (S100), a target cell determination step (S200), a comparison step (S300), a minimum voltage ratio determination step (S400), and a diagnostic step (S500).

[0184] The data acquisition step (S100) is a step of acquiring voltage information for each of a plurality of battery cells included in a battery pack, and can be performed by the data acquisition unit (110).

[0185] The target cell determination step (S200) is a step of determining the target cell and the remaining battery cells among a plurality of battery cells, and can be performed by the processor (120).

[0186] Specifically, the processor (120) can sequentially determine each of the plurality of battery cells as a target cell and diagnose the state of the plurality of battery cells. For example, the processor (120) can determine one of the plurality of battery cells as a target cell and diagnose the state of the target cell. Subsequently, until the state of all the plurality of battery cells is diagnosed, the processor (120) can determine one of the battery cells that has not been determined as a target cell as a target cell and diagnose the state of the target cell.

[0187] The comparison step (S300) is a step of comparing the voltage value of a target cell with the voltage value of the remaining battery cells in each of a plurality of preset SOC intervals, and can be performed by a processor (120).

[0188] Specifically, the processor (120) can compare the voltage value of the target cell with the voltage value of each of the remaining battery cells. Here, the voltage comparison between the target cell and the remaining battery cells can be performed for each SOC interval. That is, the processor (120) can compare the voltage between the target cell and the remaining battery cells in each SOC interval.

[0189] Specifically, the processor (120) can compare the voltage value of the target cell measured at the same time with the voltage value of each of the remaining battery cells.

[0190] For example, if the voltage is measured n times in a certain SOC interval, the processor (120) can compare the voltage value of the target cell measured at the same time with the voltage value of each of the remaining battery cells a total of n times.

[0191] The minimum voltage ratio determination step (S400) is a step of determining the minimum voltage ratio of a target cell corresponding to each of a plurality of SOC intervals based on a comparison result, and can be performed by a processor (120).

[0192] For example, if the voltage is measured n times in a certain SOC interval and the target cell is determined to be the m minimum voltage cell, the processor (120) can calculate the minimum voltage ratio of the target cell as m÷n.

[0193] As another example, the processor (120) can determine a plurality of minimum voltage ratios based on a reference time for each of a plurality of SOC intervals and a determined plurality of minimum voltage times.

[0194] The diagnosis step (S500) is a step of diagnosing the state of a target cell based on a determined plurality of minimum voltage ratios, and can be performed by a processor (120).

[0195] For example, the processor (120) can diagnose the state of the target cell as normal or abnormal based on the minimum voltage ratio for each section calculated for the target cell. For example, the processor (120) can diagnose the target cell as a normal cell, a low-voltage cell, a high-capacity cell, or a low-capacity cell.

[0196]

[0197] Another embodiment of the present invention may provide a computer-readable recording medium having a program recorded thereon for executing the various embodiments described above on a computer.

[0198] A program may be implemented as hardware components, software components, and / or a combination of hardware and software components. A program may be executed by any system capable of executing computer-readable instructions.

[0199] Software may include computer programs, code, instructions, or a combination thereof, and may configure a processing unit to operate as desired or command the processing unit independently or collectively.

[0200] Software can be implemented as a computer program containing instructions stored on a computer-readable storage medium. Examples of computer-readable storage media include magnetic storage media (e.g., ROM (read-only memory), RAM (random-access memory), floppy disks, hard disks, etc.) and optical reading media (e.g., CD-ROMs, DVDs (Digital Versatile Discs)). Computer-readable storage media can be distributed across networked computer systems, allowing computer-readable code to be stored and executed in a distributed manner. The storage medium is readable by a computer, stored in memory, and can be executed by a processor.

[0201] Computer-readable recording media may be provided in the form of non-transitory recording media. Here, 'non-transitory storage media' simply means that it is a tangible device and does not contain a signal (e.g., electromagnetic waves), and the term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily. For example, 'non-transitory storage media' may include a buffer in which data is stored temporarily.

[0202] In addition, the program may be provided as part of a computer program product. Computer program products may be traded between a seller and a buyer as goods.

[0203] A computer program product may include a software program or a computer-readable recording medium on which the software program is stored. For example, a computer program product may include a product in the form of a software program that is distributed electronically through a manufacturer of an electronic device or an electronic market (e.g., a downloadable application). For electronic distribution, at least a portion of the software program may be stored on a recording medium or temporarily created. In this case, the recording medium may be a server of the manufacturer of the electronic device, a server of the electronic market, or a recording medium of a relay server that temporarily stores the software program.

[0204]

[0205] The embodiments of the present invention described above are not limited to implementation 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 such a program is recorded. Such implementation can be easily achieved by a person skilled in the art to which the present invention pertains, based on the description of the embodiments described above.

[0206] 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 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.

[0207] Furthermore, since the present invention described above allows for various substitutions, modifications, and changes within the scope of the technical concept of the present invention to those skilled in the art without departing from the technical spirit of the present invention, it is not limited by the aforementioned embodiments and attached drawings, but rather all or part of each embodiment may be selectively combined to allow for various modifications.

[0208]

[0209] (Explanation of symbols)

[0210] 1: Car

[0211] 2: Server

[0212] 3: BMS

[0213] 4: User terminal

[0214] 10: Battery pack

[0215] 11: Battery Array

[0216] 12: Measurement section

[0217] 100: Battery Diagnostic Device

[0218] 110: Data acquisition unit

[0219] 120: Processor

[0220] 130: Storage section

Claims

1. A data acquisition unit configured to acquire voltage information of each of a plurality of battery cells included in a battery pack; and A battery diagnostic device comprising a processor configured to determine a target cell and a remaining battery cell among a plurality of battery cells, compare the voltage value of the target cell with the voltage value of the remaining battery cell in each of a plurality of preset SOC intervals, determine the minimum voltage ratio of the target cell corresponding to each of the plurality of SOC intervals based on the comparison result, and diagnose the state of the target cell based on the determined plurality of minimum voltage ratios.

2. In Paragraph 1, The above processor is, A battery diagnostic device configured to determine the minimum voltage time of the target cell for each of the plurality of SOC intervals based on a comparison result, and to determine the plurality of minimum voltage ratios based on the reference time for each of the plurality of SOC intervals and the determined plurality of minimum voltage times.

3. In Paragraph 2, The above processor is, A battery diagnostic device configured to determine the minimum voltage ratio according to the ratio of the minimum voltage time to the reference time for each of the plurality of SOC intervals.

4. In Paragraph 1, The above processor is, A battery diagnostic device configured to diagnose the state of the target cell as a low voltage state when the above plurality of minimum voltage ratios are greater than or equal to a preset first threshold.

5. In Paragraph 1, The above processor is, The above plurality of SOC sections are divided into one or more upper SOC sections and one or more lower SOC sections, and A battery diagnostic device configured to compare a minimum voltage ratio corresponding to each of the above one or more upper SOC sections and the above one or more lower SOC sections with at least one of a second threshold value preset to correspond to a high capacity state and a third threshold value preset to correspond to a low capacity state, and to diagnose the state of the target cell based on the comparison result.

6. In Paragraph 5, The above processor is, A battery diagnostic device configured to diagnose the state of the target cell as the high capacity state when the minimum voltage ratio corresponding to each of the one or more upper SOC sections is greater than or equal to the second threshold value, and the minimum voltage ratio corresponding to each of the one or more lower SOC sections is less than the second threshold value.

7. In Paragraph 5, The above processor is, A battery diagnostic device configured to diagnose the state of the target cell to the low capacity state when the minimum voltage ratio corresponding to each of the one or more upper SOC sections is less than the third threshold and the minimum voltage ratio corresponding to each of the one or more lower SOC sections is greater than or equal to the third threshold.

8. In Paragraph 5, The above processor is, Based on a differential profile representing the correspondence between the differential voltage and SOC of the battery pack, the entire SOC range is divided into the plurality of SOC ranges, and A battery diagnostic device configured to divide the plurality of SOC sections into one or more upper SOC sections and one or more lower SOC sections based on a first reference peak and a second reference peak included in the differential profile.

9. In Paragraph 5, The above third threshold is a battery diagnostic device that is preset to a value less than the above second threshold.

10. In Paragraph 1, The above processor is, A battery diagnostic device configured to determine a plurality of peaks from a differential profile representing the correspondence relationship between the differential voltage and SOC of the battery pack, and to divide the entire SOC range into the plurality of SOC ranges based on the SOC of the plurality of peaks.

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

12. An automobile comprising a battery diagnostic device according to any one of paragraphs 1 through 10.

13. A server comprising a battery diagnostic device according to any one of paragraphs 1 through 10.

14. A data acquisition step for acquiring voltage information of each of a plurality of battery cells included in a battery pack; A target cell determination step for determining a target cell and the remaining battery cells among the plurality of battery cells above; A comparison step of comparing the voltage value of the target cell with the voltage value of the remaining battery cells in each of the preset multiple SOC intervals; A minimum voltage ratio determination step for determining the minimum voltage ratio of the target cell corresponding to each of the plurality of SOC intervals based on the comparison result; and A battery diagnostic method comprising a diagnostic step for diagnosing the state of the target cell based on a determined plurality of minimum voltage ratios.

15. A computer-readable recording medium having a program recorded thereon for performing the battery diagnostic method of paragraph 14 on a computer.

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