Battery diagnosis device and method

Abstract

A battery diagnosis device according to an embodiment of the present invention comprises: a profile acquisition unit configured to acquire a differential profile representing a correspondence relationship between a differential capacity and a voltage of a battery; and a control unit configured to determine a target peak among one or more peaks included in the differential profile, determine a differential capacity increase / decrease pattern on the basis of preset differential capacity data and a differential capacity of the target peak, and diagnose a state of the battery on the basis of the determined differential capacity increase / decrease pattern.

Description

Battery diagnostic device and method

[0001] The present invention relates to a battery diagnostic device and method for diagnosing the condition of a battery.

[0002] This application claims priority based on Korean Application No. 10-2024-0190065 filed on December 18, 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] However, lithium-ion batteries degrade with repeated use, which can lead to reduced battery performance and safety. Accordingly, accurately determining whether a battery has reached the End of Life (EOL) state and taking appropriate measures is crucial for maintaining battery performance and safety.

[0007] Various methods have been used in conventional technology to diagnose the End-of-Life (EOL) state. Generally, conventional methods have diagnosed whether a battery has reached EOL based on criteria such as increased internal resistance, decreased capacity, the number of cycles used, and voltage fluctuation patterns. While these methods have the advantage of being relatively simple to apply, they have several limitations. For example, internal resistance is highly dependent on temperature and charge / discharge conditions, making it prone to errors. Furthermore, since decreased capacity and the number of cycles used do not adequately reflect the actual degradation state of the battery, the reliability of the diagnosis is compromised when the battery is used under various operating conditions. In addition, because battery degradation is caused by complex rather than single factors, there are limitations to accurately diagnosing whether the EOL state has been reached using only a single indicator.

[0008] For example, State of Health (SOH), which expresses the current state as a percentage compared to the initial state of the battery, has the advantage of being simple and intuitive. Figure 1 is a schematic diagram illustrating the change in SOH according to the cycle. Referring to Figure 1, SOH shows a pattern of gradually decreasing as the number of cycles increases. However, there is room for subjective interpretation when diagnosing the End-of-Life (EOL) point or whether EOL has been reached based on this SOH curve. In particular, even batteries with the same SOH value can have significantly different remaining lifespans or safety depending on usage conditions or degradation mechanisms. Therefore, there are limitations in accurately and consistently diagnosing whether a battery has reached EOL based solely on SOH.

[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 accurately and consistently diagnosing whether a battery has reached the EOL state.

[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 profile acquisition unit configured to acquire a differential profile representing a correspondence relationship between the voltage and differential capacity of a battery; and a control unit configured to determine a target peak among one or more peaks included in the differential profile, determine a differential capacity increase / decrease pattern based on preset differential capacity data and the differential capacity of the target peak, and diagnose the state of the battery based on the determined differential capacity increase / decrease pattern.

[0014] The above differential capacity data can be configured to store the differential capacity of the target peak determined for each cycle.

[0015] The above control unit may be configured to determine the differential capacity increase / decrease pattern as an increase pattern or a decrease pattern.

[0016] The control unit above may be configured to diagnose the state of the battery as normal or abnormal based on the differential capacity increase / decrease pattern.

[0017] The control unit may be configured to diagnose the state of the battery as the normal state when the differential capacity increase / decrease pattern is the decrease pattern.

[0018] The above control unit may be configured to diagnose the state of the battery as the abnormal state when the differential capacity increase / decrease pattern is the increase pattern.

[0019] The control unit may be configured to diagnose the state of the battery as abnormal when the SOH of the battery is below a preset reference SOH and the differential capacity increase / decrease pattern is the increase pattern.

[0020] The above control unit may be configured to calculate the differential capacity change rate based on the differential capacity data and the differential capacity of the target peak.

[0021] The control unit may be configured to diagnose the state of the battery as the abnormal state when the differential capacity increase / decrease pattern is the increase pattern and the differential capacity change rate is greater than or equal to a preset reference change rate.

[0022] The control unit may be configured to diagnose the state of the battery as the abnormal state when a maximum point exists in the differential capacity data and the differential capacity increase / decrease pattern is the increase pattern.

[0023] The control unit may be configured to determine the peak among the one or more peaks, in which the corresponding voltage is greater than or equal to a preset reference voltage, as the target peak.

[0024] The control unit may be configured to determine the peak with the largest corresponding voltage among the plurality of peaks as the target peak when there are multiple peaks among the one or more peaks in which the corresponding voltage is greater than or equal to the reference voltage.

[0025] A battery pack according to another aspect of the present invention may include the battery diagnostic device.

[0026] A vehicle according to another aspect of the present invention may include the battery diagnostic device.

[0027] A server according to another aspect of the present invention may include the battery diagnostic device.

[0028] A battery diagnostic method according to another aspect of the present invention may include: a profile acquisition step of acquiring a battery profile representing a correspondence relationship between the voltage and capacity of a battery; a differential profile generation step of generating a differential profile representing a correspondence relationship between the voltage and differential capacity based on the battery profile; a target peak determination step of determining a target peak among one or more peaks included in the differential profile; a rate of change calculation step of calculating the rate of change of differential capacity of the target peak; and a diagnostic step of diagnosing the state of the battery based on the rate of change of differential capacity.

[0029] 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.

[0030]

[0031] According to one aspect of the present invention, it is possible to accurately and consistently diagnose whether a battery has reached the EOL state.

[0032] 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.

[0033]

[0034] 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.

[0035] Figure 1 is a schematic diagram illustrating the change in SOH according to the cycle.

[0036] FIG. 2 is a schematic diagram illustrating a battery diagnostic device according to one embodiment of the present invention.

[0037] Figure 3 is a schematic diagram illustrating an example of a differential profile.

[0038] FIG. 4 is a schematic diagram illustrating an example of a first profile showing the change in differential capacity of a target peak according to a cycle.

[0039] FIG. 5 is a schematic diagram illustrating another example of a second profile showing the change in differential capacity of the target peak according to the cycle.

[0040] FIG. 6 is a schematic diagram illustrating a battery pack according to another embodiment of the present invention.

[0041] FIG. 7 is a schematic drawing illustrating an automobile according to another embodiment of the present invention.

[0042] FIG. 8 is a schematic diagram illustrating a server according to another embodiment of the present invention.

[0043] FIG. 9 is a schematic diagram illustrating a battery diagnostic method according to another embodiment of the present invention.

[0044]

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051]

[0052] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0053] FIG. 2 is a schematic diagram illustrating a battery diagnostic device (100) according to one embodiment of the present invention.

[0054] Referring to FIG. 2, the battery diagnostic device (100) may include a profile acquisition unit (110) and a control unit (120). The battery diagnostic device (100) may further include a storage unit (130).

[0055] The profile acquisition unit (110) can be configured to acquire a differential profile that represents the corresponding relationship between the voltage and differential capacity of the battery.

[0056] Here, a battery 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. Additionally, the battery may be of the cylindrical, prismatic, or pouch type. Furthermore, a battery may refer to a battery bank, battery module, or battery pack in which multiple cells are connected in series and / or parallel. For the sake of convenience of explanation, the term "battery" below is described as referring to a single, independent cell.

[0057] Differential capacitance is expressed as “dQ / dV” and refers to the value obtained by differentiating capacitance (Q) with respect to voltage (V). In other words, differential capacitance can be described as the instantaneous rate of change of capacitance (Q) with respect to voltage (V).

[0058] FIG. 3 is a schematic diagram illustrating an example of a differential profile (P_D). In the embodiment of FIG. 3, the horizontal axis represents voltage (V), and the vertical axis represents differential capacity (dQ / dV). However, it should be noted that the differential profile (P_D) of FIG. 3 is expressed in the form of a graph only for convenience of explanation, and there are no restrictions on the format in which the differential profile is expressed as long as a corresponding relationship between the voltage and differential capacity of the battery is shown.

[0059] The differential profile (P_D) is generated based on voltage data and capacity data obtained during the process of charging or discharging the battery. For example, the differential profile (P_D) may represent the correspondence between the voltage and the differential capacity when the battery's SOC is charged from a preset charging SOC or 0% to a preset charging end SOC or 100%. As another example, the differential profile (P_D) may represent the correspondence between the voltage and the differential capacity when the battery's SOC is discharged from a preset discharging start SOC or 100% to a preset discharging end SOC or 0%.

[0060] There is no specific limit on the C-rate during charging or discharging for generating the differential profile (P_D). However, preferably, to obtain a more accurate differential profile (P_D), the battery must be charged or discharged at a low rate. For example, the differential profile (P_D) can be generated based on voltage data and capacity data obtained during the process of charging or discharging the battery at 0.05C.

[0061] In one embodiment, the profile acquisition unit (110) can directly measure the voltage and current of the battery. Specifically, the profile 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, respectively. Then, the profile acquisition unit (110) can measure the voltage across the two ends of the battery based on the voltage difference between the measured positive voltage and the negative voltage. The profile acquisition unit (110) can measure the current of the battery by connecting to the battery through a current measurement unit. For example, the current measurement unit may be a current sensor or a shunt resistor that is provided in the battery's charge / discharge path to measure the battery's current. Here, the battery's charge / discharge path may be a high-current path where a charging current is applied to the battery or a discharging current is output from the battery. Then, the profile acquisition unit (110) can generate a differential profile (P_D) based on the measured voltage and current.

[0062] In another embodiment, the profile acquisition unit (110) can receive voltage data and capacity data (or current data) of the battery from the outside. That is, the profile acquisition unit (110) can receive voltage data and capacity data from the outside by being connected via wired and / or wireless so as to be able to communicate with the outside. For example, the profile acquisition unit (110) can receive voltage data and capacity data from the outside using CAN (Controller Area Network) communication or CAN-FD (CAN with Flexible Data rate) communication. As another example, the profile acquisition unit (110) can receive voltage data and capacity data from the outside using Zigbee, Bluetooth, WIFI, or a mobile communication network. Of course, as long as communication between the profile acquisition unit (110) and the outside is supported, the type of communication protocol is not particularly limited. And, the profile acquisition unit (110) can generate a differential profile (P_D) based on the received voltage data and capacity data.

[0063] In another embodiment, the profile acquisition unit (110) can receive a differential profile (P_D) from the outside.

[0064] The profile acquisition unit (110) can be connected to communicate with the control unit (120). For example, the profile acquisition unit (110) can be connected to the control unit (120) via wired and / or wireless connections. The profile acquisition unit (110) can transmit the acquired differential profile (P_D) to the control unit (120).

[0065] The control unit (120) may be configured to determine a target peak (p_t) among one or more peaks included in the differential profile (P_D).

[0066] Here, the peak may be a point in the differential profile (P_D) that has an upwardly convex shape. Specifically, the peak is a point in the differential profile (P_D) where the instantaneous rate of change is zero, and with respect to the peak, the instantaneous rate of change on the low-voltage side of the differential profile (P_D) may be positive, and the instantaneous rate of change on the high-voltage side may be negative. In other words, the peak refers to a maximum point included in the differential profile (P_D).

[0067] Specifically, the control unit (120) can determine one of the one or more peaks included in the differential profile (P_D) as the target peak (p_t) based on the voltage.

[0068] Preferably, the control unit (120) may be configured to determine, among one or more peaks, a peak in which the corresponding voltage is greater than or equal to a preset reference voltage as the target peak (p_t).

[0069] Here, the reference voltage is a reference value for determining the target peak (p_t) and can be pre-set based on theoretical analysis and / or experimental results. For example, if the battery to be diagnosed is a high-nickel (High-Ni) lithium-ion battery with an increased nickel (Ni) content, the reference voltage can be set to a value around 4V (e.g., 3.9V to 4V). Meanwhile, representative examples of high-nickel batteries include NCM811, which has a nickel, cobalt, and manganese ratio of 8:1:1, or NCA, which has a nickel content of about 80–90%.

[0070] For example, in the embodiment of FIG. 3, the differential profile (P_D) may include a first peak (p1), a second peak (p2), a third peak (p3), a fourth peak (p4), and a fifth peak (p5). The control unit (120) may determine the fifth peak (p5), which is greater than or equal to the reference voltage (4V) among the first to fifth peaks (p1, p2, p3, p4, p5), as the target peak (p_t).

[0071] The control unit (120) can be configured to determine a differential capacity increase / decrease pattern based on preset differential capacity data and the differential capacity of the target peak (p_t).

[0072] Here, the differential capacity data can be configured to store the differential capacity of the target peak (p_t) determined for each cycle.

[0073] Specifically, the differential capacity data consists of the differential capacity values ​​of the target peak (p_t) of each of the multiple differential profiles (P_D) acquired during several cycles prior to the diagnosis point.

[0074] For example, assuming the battery has undergone 100 cycles, the differential capacity value of the target peak (p_t) can be calculated from the differential profile (P_D) obtained in each cycle. The 100 calculated differential capacity values ​​can be stored in a database.

[0075] As another example, the differential capacity data may be configured to selectively store data based on regular intervals rather than storing all cycle data. For instance, assuming the battery has undergone 100 cycles, differential capacity values ​​may be stored in the database at intervals of 10 cycles. In this case, the differential capacity data may include differential capacity values ​​of the target peak (p_t) for cycles 1, 11, 21, 31, 41, etc.

[0076] As another example, differential capacity data can be structured around the latest data needed to diagnose the current state. For instance, assuming the battery has undergone 100 cycles, the differential capacity data can be configured to store only the target peak (p_t) differential capacity values ​​for the most recent 10 cycles (cycles 91–100).

[0077] Meanwhile, the method of configuring differential capacity data is not limited to the embodiments described above, and various modifications and applications are possible within the technical scope of the present invention.

[0078] The differential capacity increase / decrease pattern refers to the manner in which the differential capacity of the target peak (p_t) changes as the cycle increases. The differential capacity increase / decrease pattern can be classified into an increase pattern and a decrease pattern.

[0079] Specifically, the control unit (120) may be configured to determine the differential capacity increase / decrease pattern as an increase pattern or a decrease pattern.

[0080] Here, an increasing pattern refers to the case where the derivative capacity value of the target peak (p_t) measured in the current cycle is greater than the derivative capacity value of the target peak (p_t) in the previous cycle. A decreasing pattern refers to the case where the derivative capacity value of the target peak (p_t) measured in the current cycle is smaller than the derivative capacity value of the target peak (p_t) in the previous cycle.

[0081] Additionally, the decrease pattern may include cases where the derivative capacity value of the target peak (p_t) measured in the current cycle is the same as the derivative capacity value of the target peak (p_t) of the previous cycle. For example, the control unit (120) may include in the decrease pattern a pattern where the derivative capacity value of the target peak (p_t) is the same as the derivative capacity value of the target peak (p_t) of the previous cycle in order to distinguish the derivative capacity increase / decrease pattern into an increase pattern and a non-increase pattern.

[0082] Specifically, the control unit (120) can determine the differential capacity increase / decrease pattern as an increase pattern or a decrease pattern by comparing the differential capacity of the target peak (p_t) with the differential capacity stored in the differential capacity data. Preferably, the control unit (120) can compare the differential capacity of the target peak (p_t) with the differential capacity of the target peak (p_t) for the most recent cycle among the differential capacities stored in the differential capacity data.

[0083] If the derivative capacity value of the target peak (p_t) is greater than the derivative capacity value of the most recent cycle stored in the derivative capacity data, the control unit (120) can determine this as an increasing pattern. Conversely, if the derivative capacity value of the target peak (p_t) is less than or equal to the derivative capacity value of the most recent cycle stored in the derivative capacity data, the control unit (120) can determine this as a decreasing pattern.

[0084] Preferably, the increase pattern may include cases where the derivative capacity of the target peak (p_t) increases by more than a preset threshold value than the derivative capacity value of the target peak (p_t) of the previous cycle. The decrease pattern may include cases where the derivative capacity of the target peak (p_t) decreases by more than a threshold value than the derivative capacity of the target peak (p_t) of the previous cycle. The decrease pattern may also include cases where the difference between the derivative capacity of the target peak (p_t) and the derivative capacity of the target peak (p_t) of the previous cycle is less than a threshold value.

[0085] For example, the threshold value may be preset to 3. An increase pattern indicates a case where the derivative capacity value of the target peak (p_t) increases by 3 or more compared to the derivative capacity value of the target peak (p_t) of the previous cycle. Conversely, a decrease pattern indicates a case where the derivative capacity value of the target peak (p_t) decreases by 3 or more compared to the derivative capacity value of the target peak (p_t) of the previous cycle. Additionally, the decrease pattern may include a case where the difference between the derivative capacity value of the target peak (p_t) and the derivative capacity value of the target peak (p_t) of the previous cycle is less than 3.

[0086] Due to various internal and / or external causes of the battery, errors may be included in the voltage and capacity measured for the battery. Additionally, errors may be reflected in the differential profile (P_D) based on these voltage and capacity data. Therefore, the control unit (120) can determine the differential capacity increase / decrease pattern while reducing the possibility of misdiagnosis due to errors by considering whether the difference between two differential capacities being compared is greater than or equal to a threshold value.

[0087] The control unit (120) may be configured to diagnose the state of the battery based on a determined differential capacity increase / decrease pattern. Specifically, the control unit (120) may be configured to diagnose the state of the battery as normal or abnormal based on the differential capacity increase / decrease pattern.

[0088] Here, a steady state refers to a condition in which the battery maintains its designed performance and operates stably during the charging and discharging process. An abnormal state means that the battery has reached the End of Life (EOL) state, which signifies a condition in which the battery has severely degraded and can no longer be used safely and stably.

[0089] As cycles are repeated, the degradation of the cathode material progresses, reducing the ability to insert and extract lithium ions, and the cathode overvoltage may increase rapidly. These changes not only lead to a decrease in the overall capacity of the battery but can also cause abnormal changes in differential capacity data in high voltage ranges above the reference voltage (e.g., 4V).

[0090] Here, abnormal changes in differential capacity data may appear as a pattern of increase or decrease in differential capacity. Specifically, as the positive overvoltage increases, the differential capacity gradually increases, so the pattern of increase or decrease in differential capacity may appear as an increase pattern. Therefore, the control unit (120) can diagnose the state of the battery by considering the pattern of increase or decrease in differential capacity.

[0091] For example, if the differential capacity increase / decrease pattern is a decrease pattern, the control unit (120) can diagnose the state of the battery as normal. As another example, if the differential capacity increase / decrease pattern is an increase pattern, the control unit (120) can diagnose the state of the battery as abnormal.

[0092] According to one embodiment of the present invention, a battery diagnostic device (100) determines a differential capacity increase / decrease pattern based on differential capacity data obtained from a previous cycle, and based thereon, can accurately and consistently diagnose whether the battery has reached an EOL state.

[0093]

[0094] Meanwhile, the profile acquisition unit (110) and / or control unit (120) provided in the battery diagnostic device (100) may optionally include a processor, an application-specific integrated circuit (ASIC), other chipsets, logic circuits, registers, communication modems, data processing devices, 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 profile acquisition unit (110) and / or control unit (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 profile acquisition unit (110) and / or control unit (120). The memory may be located inside or outside the profile acquisition unit (110) and / or control unit (120) and may be connected to the profile acquisition unit (110) and / or control unit (120) by various well-known means.

[0095] 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 profile acquisition unit (110) and / or the control unit (120) are defined.

[0096] Specifically, the storage unit (130) can store information necessary for the control unit (120) to diagnose the state of the battery. For example, the storage unit (130) can store differential capacity data, threshold value, reference SOH, reference rate of change, and reference voltage. And, the control unit (120) can access the storage unit (130) to obtain information necessary for the control unit (120) to diagnose the state of the battery. For example, the differential profile (P_D) obtained by the profile acquisition unit (110) is stored in the storage unit (130), and the control unit (120) can access the storage unit (130) to obtain the stored differential profile (P_D).

[0097]

[0098] Hereinafter, a specific embodiment in which the control unit (120) diagnoses the state of the battery is described with reference to FIG. 4.

[0099] FIG. 4 is a schematic diagram illustrating an example of a first profile (P1) showing the change in differential capacity of a target peak (p_t) according to the cycle. In FIG. 4, the horizontal axis represents the cycle (times), and the vertical axis represents the differential capacity (dQ / dV).

[0100] Referring to Figure 4, it can be seen that the differential capacity of the target peak (p_t) shows a decreasing-increasing change.

[0101] If the differential capacity increase / decrease pattern is a decrease pattern, the control unit (120) can be configured to diagnose the state of the battery as normal.

[0102] For example, if the differential capacity value of the target peak (p_t) is smaller than the differential capacity value of the most recent cycle stored in the differential capacity data, the control unit (120) can diagnose the state of the battery as normal.

[0103] Conversely, if the differential capacity increase / decrease pattern is an increase pattern, the control unit (120) may be configured to diagnose the battery's condition as abnormal.

[0104] For example, if the differential capacity value of the target peak (p_t) is greater than the differential capacity value of the most recent cycle stored in the differential capacity data, the control unit (120) can diagnose the battery condition as abnormal.

[0105] Referring to FIG. 4, the first section represents a section where the differential capacity of the target peak (p_t) decreases as the cycle increases, and the second section represents a section where the differential capacity of the target peak (p_t) increases as the cycle increases. The boundary between the first and second sections is 175 cycles, which is a cycle where the instantaneous rate of change of the differential capacity is zero.

[0106] In the embodiment of FIG. 4, if the diagnosis time is included in the first interval, the state of the battery at the diagnosis time can be diagnosed as normal. If the diagnosis time is included in the second interval, the state of the battery at the diagnosis time can be diagnosed as abnormal.

[0107]

[0108] Hereinafter, a specific embodiment in which the control unit (120) diagnoses the state of the battery is described with reference to FIG. 5.

[0109] FIG. 5 is a schematic diagram illustrating another example of a second profile (P2) showing the change in differential capacity of a target peak (p_t) according to the cycle. In FIG. 5, the horizontal axis represents the cycle (times), and the vertical axis represents the differential capacity (dQ / dV).

[0110] Referring to Figure 5, it can be seen that the differential capacity of the target peak (p_t) shows a change in the form of increase-decrease-increase.

[0111] The control unit (120) can diagnose the state of the battery based on the battery's SOH and differential capacity increase / decrease pattern.

[0112] The control unit (120) can estimate the current SOH of the battery. However, since the technique of estimating SOH using battery information such as the voltage, capacity, and resistance of the battery is already widely known, a detailed explanation thereof is omitted.

[0113] For example, if the battery's SOH is below a preset reference SOH and the differential capacity increase / decrease pattern is an increase pattern, the control unit (120) may be configured to diagnose the battery's state as abnormal. As another example, if the battery's SOH exceeds the reference SOH, the control unit (120) may diagnose the battery's state as normal. As yet another example, if the differential capacity increase / decrease pattern is a decrease pattern, the control unit (120) may diagnose the battery's state as normal regardless of the battery's SOH.

[0114] Here, the reference SOH refers to the SOH at which the battery operates normally and before reaching the EOL state. For example, the reference SOH is a threshold value set to prevent differential capacity growth patterns that may appear during initial cycles from being misdiagnosed as an abnormal state caused by degradation. Specifically, the differential capacity of the target peak (p_t) may increase due to the electrochemical activation of the cathode material rather than battery degradation. Therefore, the reference SOH can be set to prevent this natural increase from being diagnosed as an abnormal state.

[0115] The reference SOH can be set through theoretical analysis and / or experimental results. For example, the reference SOH can be preset based on the change in differential capacity of the target peak (p_t) per cycle and the SOH of a reference battery of the same type as the battery being diagnosed. Specifically, the reference SOH can be set to a value that is less than or equal to a first SOH corresponding to the maximum point of the reference profile and greater than or equal to a second SOH corresponding to the minimum point of the reference profile. For example, the reference SOH can be set to 95%.

[0116] Referring to FIG. 5, the change in the differential capacity of the target peak (p_t) can be divided into three sections. The first section is a section where the differential capacity of the target peak (p_t) increases as the cycle increases, the second section is a section where the differential capacity of the target peak (p_t) decreases as the cycle increases, and the third section is a section where the differential capacity of the target peak (p_t) increases again as the cycle increases. The boundary between the first and second sections is 40 cycles, at which point the instantaneous rate of change of the differential capacity becomes 0. The boundary between the second and third sections is 175 cycles, at which point the instantaneous rate of change of the differential capacity also becomes 0.

[0117] In the embodiment of FIG. 5, the cycle corresponding to the reference SOH may be located between 40 cycles and 175 cycles. When the diagnosis time is included in the first interval, the differential capacity increase / decrease pattern is an increase pattern, but since the battery's SOH exceeds the reference SOH, the control unit (120) can diagnose the battery's state as normal. When the diagnosis time is included in the second interval, since the differential capacity increase / decrease pattern is a decrease pattern, the control unit (120) can diagnose the battery's state as normal regardless of the battery's SOH. On the other hand, when the diagnosis time is included in the third interval, since the differential capacity increase / decrease pattern is an increase pattern and the battery's SOH is below the reference SOH, the control unit (120) can diagnose the battery's state as abnormal.

[0118] A battery diagnostic device (100) according to one embodiment of the present invention can diagnose the condition of a battery more accurately by further considering the SOH as well as the differential capacity increase / decrease pattern. In particular, since the battery diagnostic device (100) can diagnose whether the battery is in a normal state based on the battery's SOH, it can diagnose the condition of the battery more quickly.

[0119]

[0120] The control unit (120) can diagnose the state of the battery based on the differential capacity change rate and the differential capacity increase / decrease pattern.

[0121] The control unit (120) can be configured to calculate the differential capacity change rate based on the differential capacity data and the differential capacity of the target peak (p_t).

[0122] Specifically, the control unit (120) can generate a cycle-derivative capacity profile representing the correspondence between cycles and derivative capacities from derivative capacity data and the derivative capacitance of the target peak (p_t). For example, the first profile of FIG. 4 and the second profile of FIG. 5 are cycle-derivative capacity profiles generated by the control unit (120).

[0123] In addition, the control unit (120) can calculate the differential capacity change rate at the time of diagnosis based on the generated cycle-differential capacity profile. For example, the control unit (120) can apply polynomial curve fitting to the cycle-differential capacity profile and then calculate the instantaneous change rate at the time of diagnosis based on this.

[0124] For example, if the differential capacity increase / decrease pattern is an increase pattern and the differential capacity change rate is greater than or equal to a preset reference change rate, the control unit (120) may be configured to diagnose the battery's condition as an abnormal state.

[0125] As another example, if the differential capacity increase / decrease pattern is a decrease pattern, the control unit (120) can diagnose the state of the battery as normal.

[0126] As another example, if the differential capacity change rate is less than the reference change rate, the control unit (120) can diagnose the battery's condition as normal.

[0127] Here, the reference rate of change is a value used to distinguish between the natural growth pattern that may appear during the initial cycle of a battery and the growth pattern caused by degradation. Generally, the differential capacity change rate during the initial cycle tends to be lower than the differential capacity change rate during the End-of-Life (EOL) state. The reference rate of change can be established through theoretical analysis and / or experimental results to reflect this trend. For example, the reference rate of change can be pre-set based on a reference profile for a reference battery. Specifically, the reference rate of change can be set by comparing the differential capacity change rate during the growth pattern of the initial cycle in the reference profile with the differential capacity change rate during the growth pattern caused by degradation. For instance, the reference rate of change can be set to a value between the maximum differential capacity change rate during the growth pattern section in the initial cycle of the reference profile and the minimum differential capacity change rate during the growth pattern section caused by degradation.

[0128] In the embodiment of FIG. 5, when the diagnosis time is included in the first interval, even if the differential capacity increase / decrease pattern corresponds to an increase pattern, it is highly likely that the differential capacity change rate is less than the reference change rate due to the natural activation process that occurs in the initial cycle. In this case, the control unit (120) can diagnose the state of the battery as normal.

[0129] If the diagnosis time falls within the second interval, the differential capacity increase / decrease pattern corresponds to a decrease pattern, which indicates that the battery is operating normally but is undergoing gradual degradation. Therefore, regardless of the differential capacity change rate, the control unit (120) can diagnose the battery's condition as normal.

[0130] On the other hand, if the diagnosis time falls within the third interval, the differential capacity increase / decrease pattern corresponds to an increase pattern, and due to degeneration, the differential capacity change rate is likely to be greater than the reference change rate. In this case, the control unit (120) can diagnose the battery's condition as abnormal.

[0131] According to one embodiment of the present invention, the battery diagnostic device (100) further considers the differential capacity change rate as well as the differential capacity increase / decrease pattern, thereby preventing the case where the normal differential capacity increase pattern appearing at the beginning of the cycle is misdiagnosed as the EOL state, and thus can diagnose the condition of the battery more accurately.

[0132]

[0133] The control unit (120) can diagnose the state of the battery based on the differential capacity increase pattern and differential capacity data.

[0134] The control unit (120) can diagnose the state of the battery based on the differential capacity increase / decrease pattern when there is a maximum point in the differential capacity data.

[0135] Specifically, the control unit (120) can generate a cycle-derivative capacity profile representing the correspondence between cycles and derivative capacity from derivative capacity data. Then, the control unit (120) can determine whether a maximum point exists based on the generated cycle-derivative capacity profile. For example, the control unit (120) can determine whether a maximum point exists after applying polynomial curve fitting to the cycle-derivative capacity profile.

[0136] For example, if there is a maximum point in the differential capacity data and the differential capacity increase / decrease pattern is an increase pattern, the control unit (120) may be configured to diagnose the state of the battery as abnormal.

[0137] As another example, if there is a maximum point in the differential capacity data and the differential capacity increase / decrease pattern is a decrease pattern, the control unit (120) can diagnose the state of the battery as normal.

[0138] In the embodiment of FIG. 5, when the diagnosis time is included in the second interval, there is a maximum point in the differential capacity data and the differential capacity increase / decrease pattern is a decrease pattern, so the control unit (120) can diagnose the state of the battery as normal. On the other hand, when the diagnosis time is included in the c interval, there is a maximum point in the differential capacity data and the differential capacity increase / decrease pattern is an increase pattern, so the control unit (120) can diagnose the state of the battery as abnormal.

[0139] According to one embodiment of the present invention, the battery diagnostic device (100) can diagnose the condition of the battery more accurately by further considering not only the differential capacity increase / decrease pattern but also whether there is a maximum point in the differential capacity data, thereby preventing the case where a normal differential capacity increase pattern appearing at the beginning of the cycle is misdiagnosed as an EOL state.

[0140]

[0141] If there are multiple peaks where the corresponding voltage is greater than or equal to the reference voltage, the control unit (120) may be configured to determine the peak with the largest corresponding voltage among the multiple peaks as the target peak (p_t).

[0142] A peak appearing at a high potential can more clearly reflect the electrochemical state of the anode. This is because, under high potential conditions, a flat region is formed where the potential change of the cathode is maintained smoothly, and the electrochemical change at the anode has a major influence on the formation of the peak. If multiple peaks exist above a reference voltage, the peak appearing at the highest voltage can more accurately reflect the state of the anode. Therefore, the battery diagnostic device (100) can diagnose the state of the battery more accurately by determining the peak with the highest corresponding voltage among the multiple peaks above the reference voltage as the target peak (p_t).

[0143]

[0144] The battery diagnostic device (100) can be configured to set usage conditions based on the results of a condition diagnosis for the battery.

[0145] For example, if the battery condition is diagnosed as normal, the control unit (120) may maintain the existing usage conditions. Conversely, if the battery condition is diagnosed as abnormal, the control unit (120) may change the existing usage conditions. For example, if the battery condition is diagnosed as abnormal, the control unit (120) may be configured to reduce the maximum charge / discharge rate. As another example, if the battery condition is diagnosed as abnormal, the control unit (120) may be configured to reduce the charge end voltage. Here, the charge end voltage may refer to the maximum voltage allowed during charging of the battery. As yet another example, if the battery condition is diagnosed as abnormal, the control unit (120) may increase the discharge end voltage. Here, the discharge end voltage may refer to the minimum voltage allowed during discharging of the battery.

[0146] Meanwhile, regarding specific embodiments for setting the usage conditions of the battery, it goes without saying that various methods easily applicable by a person skilled in the art to which the present invention belongs can be used.

[0147] A battery diagnostic device (100) according to one embodiment of the present invention can mitigate performance degradation of the battery and improve lifespan and stability by appropriately controlling the usage conditions of the battery in consideration of the condition diagnosis results of the battery.

[0148] 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 profile acquisition unit (110), control unit (120), and storage unit (130) of the battery diagnostic device (100) may be implemented as components of the BMS.

[0149] FIG. 6 is a schematic diagram illustrating a battery pack (10) according to another embodiment of the present invention.

[0150] 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 one or more battery cells. In addition, the battery pack (10) may further include electrical components (relays, fuses, etc.) and a case, etc.

[0151] The positive terminal of the battery (11) can be connected to the positive terminal (P+) of the battery pack (10), and the negative terminal of the battery (11) can be connected to the negative terminal (P-) of the battery pack (10).

[0152] The measuring unit (12) can be connected to the first sensing line (SL1), the second sensing line (SL2), and the third sensing line (SL3). Specifically, the measuring unit (12) can be connected to the positive terminal of the battery (11) through the first sensing line (SL1) and to the negative terminal of the battery (11) through the second sensing line (SL2). The measuring unit (12) can measure the voltage of the battery (11) based on the voltage measured at each of the first sensing line (SL1) and the second sensing line (SL2).

[0153] Additionally, the measuring unit (12) can be connected to a current measuring unit (A) through a third sensing line (SL3). 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 (11). The measuring unit (12) can calculate the charging amount by measuring the charging current of the battery (11) through the third sensing line (SL3). Furthermore, the measuring unit (12) can calculate the discharging amount by measuring the discharging current of the battery (11) through the third sensing line (SL3).

[0154] The battery diagnostic device (100) can be connected via wired and / or wireless means to communicate with the measurement unit (12). The profile acquisition unit (110) can receive voltage information and / or current information of the battery (11) from the measurement unit (12).

[0155]

[0156] FIG. 7 is a schematic drawing of a vehicle (1) according to another embodiment of the present invention.

[0157] Referring to FIG. 7, the battery pack (10) of FIG. 6 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).

[0158]

[0159] FIG. 8 is a schematic diagram illustrating a server (2) according to another embodiment of the present invention.

[0160] Referring to FIG. 8, the battery diagnostic device (100) according to the present invention may be provided in a server (2). The server (2) may provide high-performance computing resources and data storage functions.

[0161] The server (2) can individually obtain differential profiles (P_D) from multiple BMSs (3) to diagnose the state of each of the multiple batteries. Specifically, the server (2) can determine a target peak (p_t) based on the differential profile (P_D), and determine a differential capacity increase / decrease pattern for each battery based on the differential capacity of the determined target peak (p_t) and differential capacity data pre-set for each battery. Then, the server (2) can diagnose the state of the battery as normal or abnormal based on the differential capacity increase / decrease pattern.

[0162] The server (2) can be linked with a plurality of BMS (3) and / or user terminals (4), etc., to perform integrated management of a battery system including a plurality of batteries. The server (2) can be connected via wired and / or wireless connections to communicate with a plurality of BMS (3) and / or user terminals (4).

[0163] The server (2) is linked with the BMS (3) and can transmit the diagnosis results for the battery in real time to the corresponding BMS (3). Alternatively, if the server (2) diagnoses that the battery condition is abnormal, it can transmit a warning or control signal to the corresponding BMS (3).

[0164] The server (2) can be linked with the user terminal (4) to allow the user to remotely monitor the status of the battery. The user can check the status of the battery in real time using a dedicated application.

[0165]

[0166] FIG. 9 is a schematic diagram illustrating a battery diagnostic method according to another embodiment of the present invention.

[0167] 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.

[0168] Referring to FIG. 9, the battery diagnostic method may include a profile acquisition step (S100), a target peak determination step (S200), a pattern determination step (S300), and a state diagnosis step (S400).

[0169] The profile acquisition step (S100) is a step of acquiring a differential profile (P_D) representing the corresponding relationship between the voltage and differential capacity of the battery, and can be performed by the profile acquisition unit (110).

[0170] The target peak determination step (S200) is a step of determining a target peak (p_t) among one or more peaks included in the differential profile (P_D), and can be performed by the control unit (120).

[0171] Specifically, the control unit (120) can determine one of the one or more peaks included in the differential profile (P_D) as the target peak (p_t) based on the voltage.

[0172] Preferably, the control unit (120) may be configured to determine, among one or more peaks, a peak in which the corresponding voltage is greater than or equal to a preset reference voltage as the target peak (p_t).

[0173] If there are multiple peaks where the corresponding voltage is greater than or equal to the reference voltage, the control unit (120) may be configured to determine the peak with the largest corresponding voltage among the multiple peaks as the target peak (p_t).

[0174] The pattern determination step (S300) is a step of determining a differential capacity increase / decrease pattern based on preset differential capacity data and the differential capacity of the target peak (p_t), and can be performed by the control unit (120).

[0175] Specifically, the control unit (120) may be configured to determine the differential capacity increase / decrease pattern as an increase pattern or a decrease pattern by considering the differential capacity data and the differential capacity of the target peak (p_t).

[0176] The state diagnosis step (S400) is a step of diagnosing the state of the battery based on a determined differential capacity increase / decrease pattern, and can be performed by the control unit (120).

[0177] Specifically, the control unit (120) may be configured to diagnose the state of the battery as normal or abnormal based on a differential capacity increase / decrease pattern.

[0178] For example, in the case of decrease-increase, if the differential capacity increase / decrease pattern is a decrease pattern, the control unit (120) may be configured to diagnose the state of the battery as normal. Conversely, if the differential capacity increase / decrease pattern is an increase pattern, the control unit (120) may be configured to diagnose the state of the battery as abnormal.

[0179] As another example, in the case of increase-decrease-increase, the control unit (120) can diagnose the state of the battery as normal or abnormal by further considering not only the differential capacity increase / decrease pattern but also the SOH, the differential capacity change rate, or the existence of a maximum point. Through this, the case where a normal differential capacity increase pattern appearing at the beginning of the cycle is misdiagnosed as an EOL state is prevented, thereby improving the reliability of the battery diagnosis.

[0180]

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188]

[0189] 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.

[0190] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0191] 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.

[0192]

[0193] (Explanation of symbols)

[0194] 1: Vehicle

[0195] 2: Server

[0196] 3: BMS

[0197] 4: User terminal

[0198] 10: Battery pack

[0199] 11: Battery

[0200] 12: Measurement section

[0201] 100: Battery Diagnostic Device

[0202] 110: Profile Acquisition Section

[0203] 120: Processor

[0204] 130: Storage section

Claims

1. A profile acquisition unit configured to acquire a differential profile representing the correspondence relationship between the voltage and differential capacity of a battery; and A battery diagnostic device comprising a control unit configured to determine a target peak among one or more peaks included in the above differential profile, determine a differential capacity increase / decrease pattern based on preset differential capacity data and the differential capacity of the target peak, and diagnose the state of the battery based on the determined differential capacity increase / decrease pattern.

2. In Paragraph 1, The above differential capacity data is, A battery diagnostic device configured to store the differential capacity of a target peak determined for each cycle.

3. In Paragraph 1, The above control unit is, A battery diagnostic device configured to determine the differential capacity increase / decrease pattern as an increase pattern or a decrease pattern, and to diagnose the state of the battery as a normal state or an abnormal state based on the differential capacity increase / decrease pattern.

4. In Paragraph 3, The above control unit is, If the above differential capacity increase / decrease pattern is the above decrease pattern, the state of the battery is diagnosed as the above normal state, and A battery diagnostic device configured to diagnose the state of the battery as the abnormal state when the differential capacity increase / decrease pattern is the increase pattern.

5. In Paragraph 3, The above control unit is, A battery diagnostic device configured to diagnose the state of the battery as abnormal when the SOH of the battery is below a preset reference SOH and the differential capacity increase / decrease pattern is the increase pattern.

6. In Paragraph 3, The above control unit is, Calculate the differential capacity change rate based on the differential capacity data and the differential capacity of the target peak, and A battery diagnostic device configured to diagnose the state of the battery as an abnormal state when the differential capacity increase / decrease pattern is the increase pattern and the differential capacity change rate is greater than or equal to a preset reference change rate.

7. In Paragraph 3, The above control unit is, A battery diagnostic device configured to diagnose the state of the battery as the abnormal state when a maximum point exists in the above differential capacity data and the above differential capacity increase / decrease pattern is the above increase pattern.

8. In Paragraph 1, The above control unit is, A battery diagnostic device configured to determine, among the above one or more peaks, the peak whose corresponding voltage is greater than or equal to a preset reference voltage as the target peak.

9. In Paragraph 8, The above control unit is, A battery diagnostic device configured to determine the peak with the largest corresponding voltage among the plurality of peaks as the target peak when there are multiple peaks among the above one or more peaks in which the corresponding voltage is greater than or equal to the reference voltage.

10. A battery pack comprising a battery diagnostic device according to any one of paragraphs 1 through 9.

11. An automobile comprising a battery diagnostic device according to any one of paragraphs 1 through 9.

12. A server comprising a battery diagnostic device according to any one of paragraphs 1 through 9.

13. A profile acquisition step for acquiring a differential profile representing the correspondence relationship between the voltage and differential capacity of a battery; A target peak determination step for determining a target peak among one or more peaks included in the above differential profile; A pattern determination step for determining a differential capacity increase / decrease pattern based on preset differential capacity data and the differential capacity of the target peak; and A battery diagnosis method comprising a state diagnosis step for diagnosing the state of the battery based on a determined differential capacity increase / decrease pattern.

14. A computer-readable recording medium having a program recorded thereon for performing the battery diagnostic method of paragraph 13 on a computer.

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