Apparatus and method for diagnosing battery

Abstract

An apparatus for diagnosing a battery, according to one embodiment of the present invention, comprises: a profile acquisition unit for acquiring a voltage profile indicating a battery voltage for a plurality of cycles; and a control unit for calculating a first voltage change rate for at least one cycle on the basis of the voltage profile, comparing the calculated at least one first voltage change rate to a preset first reference change rate, and diagnosing the state of the battery on the basis of the comparison result.

Description

Battery diagnostic device and method

[0001] This application claims priority to Korean Patent Application No. 10-2024-0092483, filed on July 12, 2024, the entire contents of which are disclosed in the specification and drawings of which are incorporated herein by reference.

[0002] The present invention relates to a battery diagnostic device and method, and more particularly, to a battery diagnostic device and method capable of diagnosing whether lithium is precipitated in a battery.

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has rapidly increased, and the development of electric vehicles, energy storage batteries, robots, and satellites has been in full swing, research into high-performance batteries capable of repeated charging and discharging is actively being conducted.

[0004] Currently commercialized batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium batteries. Among these, lithium batteries are receiving attention for their advantages of being able to charge and discharge freely, having a very low self-discharge rate, and having a high energy density, as they have almost no memory effect compared to nickel-based batteries.

[0005] While extensive research is being conducted on these batteries to improve capacity and density, improving lifespan and safety is also crucial. To improve battery safety, technology is required to accurately diagnose the current battery condition.

[0006] In particular, it is necessary to prevent lithium plating on the cathode surface. Lithium plating on the cathode surface can cause side reactions with the electrolyte and alter the battery's kinetic balance, leading to battery degradation.

[0007] The present invention has been devised to solve the above problems, and its purpose is to provide a battery diagnostic device and method capable of diagnosing whether lithium is precipitated in a battery.

[0008] Other objects and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0009] A battery diagnostic device according to one aspect of the present invention may include a profile acquisition unit configured to acquire a voltage profile representing a voltage of a battery for a plurality of cycles; and a control unit configured to calculate a first voltage change rate for at least one cycle based on the voltage profile, compare the calculated at least one first voltage change rate with a preset first reference change rate, and diagnose a state of the battery based on the comparison result.

[0010] The control unit may be configured to diagnose the state of the battery as a lithium plating state if at least one of the first voltage change rates is greater than or equal to the first reference change rate.

[0011] The control unit may be configured to select a target cycle corresponding to the first voltage change rate that is greater than or equal to the first reference change rate, determine a cycle section for the selected target cycle based on a preset section size, and diagnose the state of the battery as a lithium plating state if at least one of the second voltage change rates for the determined cycle section is greater than or equal to the preset second reference change rate.

[0012] The above first reference change rate can be preset to a value greater than or equal to the second reference change rate.

[0013] The above first reference change rate may be preset to a value lower than or equal to a voltage change rate corresponding to the first cycle of the voltage profile.

[0014] The control unit may be configured to calculate the first voltage change rate for each of the plurality of cycles, select a target cycle among the plurality of cycles in which the corresponding first voltage change rate is greater than or equal to the first reference change rate, and determine the minimum cycle among the selected target cycles as the start cycle of lithium plating.

[0015] The control unit may be configured to determine a cycle section for the selected target cycle based on a preset section size, calculate a second voltage change rate for the determined cycle section, and determine a minimum cycle among the selected target cycles in which the corresponding second voltage change rate is greater than or equal to a preset second reference change rate as the start cycle of the lithium plating.

[0016] The above control unit may be configured to calculate the first voltage change rate for a cycle greater than or equal to a preset reference cycle among the plurality of cycles.

[0017] The control unit may be configured to set usage conditions of the battery, including at least one of a maximum allowable C-rate, a maximum allowable temperature, and a maximum allowable SOC, based on the state of the battery.

[0018] The voltage of the battery may be the OCV of the battery measured after discharge of the battery is completed in each of the plurality of cycles.

[0019] A battery pack according to another aspect of the present invention may include a battery diagnostic device according to one aspect of the present invention.

[0020] A server according to another aspect of the present invention may include a battery diagnostic device according to one aspect of the present invention.

[0021] A battery diagnosis method according to another aspect of the present invention may include a profile acquisition step of acquiring a voltage profile representing a voltage of a battery for a plurality of cycles; a voltage change rate calculation step of calculating a first voltage change rate for at least one cycle based on the voltage profile; a comparison step of comparing the calculated at least one first voltage change rate with a preset first reference change rate; and a battery condition diagnosis step of diagnosing a condition of the battery based on a comparison result of the comparison step.

[0022] According to one aspect of the present invention, a battery diagnostic device has the advantage of being able to non-destructively diagnose whether lithium plating has occurred in a battery based on the cycle-by-cycle voltage change rate of the battery.

[0023] Additionally, the battery diagnostic device has the advantage of being able to diagnose the starting point of lithium plating (start cycle).

[0024] Additionally, the battery diagnostic device has the advantage of being able to set the battery's usage conditions to prevent further lithium plating even if lithium plating has already occurred on the battery.

[0025] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0026] The following drawings attached to this specification serve to further understand the technical idea of ​​the present invention together with the detailed description of the invention described below, and therefore the present invention should not be interpreted as being limited to the matters described in such drawings.

[0027] FIG. 1 is a schematic diagram illustrating a battery diagnostic device according to one embodiment of the present invention.

[0028] FIG. 2 is a diagram illustrating an example of a first voltage profile according to one embodiment of the present invention.

[0029] Figure 3 is a schematic diagram illustrating a differential profile for the first voltage profile.

[0030] FIG. 4 is a diagram illustrating another embodiment of a first voltage profile according to one embodiment of the present invention.

[0031] Figure 5 is a schematic diagram illustrating the first to fifth voltage profiles.

[0032] FIG. 6 is a schematic drawing of a battery pack according to another embodiment of the present invention.

[0033] FIG. 7 is a schematic diagram illustrating a server according to another embodiment of the present invention.

[0034] FIG. 8 is a schematic drawing of a vehicle according to another embodiment of the present invention.

[0035] FIG. 9 is a schematic diagram illustrating a battery diagnosis method according to another embodiment of the present invention.

[0036] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0037] Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0038] In addition, when describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description is omitted.

[0039] Terms that include ordinal numbers, such as first, second, etc., are used to distinguish one of the various components from the rest, and are not used to limit the components by such terms.

[0040] Throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0041] Additionally, throughout the specification, when we say that a part is "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "indirectly connected" with other elements in between.

[0042]

[0043] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0044] FIG. 1 is a schematic diagram illustrating a battery diagnostic device (100) according to one embodiment of the present invention.

[0045] Referring to FIG. 1, the battery diagnostic device (100) may include a profile acquisition unit (110) and a control unit (120).

[0046] Here, a battery refers to a physically separate, independent cell having a negative terminal and a positive terminal. For example, a lithium-ion battery or a lithium polymer battery may be considered a battery. Furthermore, the battery may be of a cylindrical type, a prismatic type, or a pouch type. Furthermore, a battery may also refer to a battery bank, a battery module, or a battery pack in which multiple cells are connected in series and / or parallel. For convenience of explanation, the term "battery" will be described herein below as referring to a single, independent cell.

[0047] The profile acquisition unit (110) may be configured to acquire a voltage profile representing the voltage of the battery for multiple cycles.

[0048] Specifically, the profile acquisition unit (110) can acquire a voltage profile in which the voltage of the corresponding battery is mapped for each cycle. Here, the voltage of the battery is a value measured for each cycle, and is a voltage value measured under the same conditions in multiple cycles.

[0049] Specifically, the battery voltage may be the battery's open circuit voltage (OCV), measured after the battery discharge is completed for each of multiple cycles. That is, once the battery voltage reaches a preset discharge termination voltage, the battery may be placed in a no-load state for a predetermined period of time. In this state, the battery's OCV may be measured, and the battery voltage for that cycle may be recorded in a voltage profile.

[0050] In one embodiment, the discharge termination voltage may be preset to a lower voltage limit set for the battery (e.g., 2.8 V).

[0051] In another embodiment, since discharging the battery to a lower voltage limit (e.g., 2.8 V) every cycle can accelerate battery degradation, the discharge end voltage may be preset to a voltage higher than the lower voltage limit. For example, the discharge end voltage may be preset to a voltage corresponding to about 10% of the State of Charge (SOC) based on the Beginning of Life (BOL) state (e.g., about 2.94 V).

[0052] FIG. 2 is a diagram illustrating an example of a first voltage profile (VP1) according to one embodiment of the present invention. Here, the first voltage profile (VP1) can be expressed as an XY graph in which the X-axis is set as a cycle and the Y-axis is set as a voltage.

[0053] For example, the profile acquisition unit (110) can directly receive the voltage profile of the battery from the outside. That is, the profile acquisition unit (110) can acquire the voltage profile by receiving the voltage profile through a wired and / or wireless connection to the outside.

[0054] As another example, the profile acquisition unit (110) can receive battery information regarding the battery voltage for each cycle. Furthermore, the profile acquisition unit (110) can generate a voltage profile based on the received battery information. In other words, the profile acquisition unit (110) can acquire a voltage profile by directly generating the voltage profile based on the battery information.

[0055] The profile acquisition unit (110) may be connected to the control unit (120) so as to be able to communicate with it. For example, the profile acquisition unit (110) may be connected to the control unit (120) by wire and / or wirelessly. The profile acquisition unit (110) may transmit the acquired voltage profile to the control unit (120).

[0056] The control unit (120) may be configured to calculate a first voltage change rate for at least one cycle based on the voltage profile.

[0057] Specifically, the control unit (120) can calculate the first voltage change rate for at least one cycle by calculating the voltage change rate for the cycle. That is, the first voltage change rate can be a value obtained by differentiating the voltage for the cycle.

[0058] The control unit (120) may calculate the first voltage change rate for one cycle included in the voltage profile, or may calculate the first voltage change rate for multiple cycles.

[0059] Fig. 3 is a schematic diagram illustrating a differential profile (DP) for a first voltage profile (VP1). Here, the differential profile (DP) can be expressed as an XY graph in which the X-axis is set to a cycle and the Y-axis is set to a first voltage change rate.

[0060] For example, in the embodiments of FIGS. 2 and 3, the control unit (120) can calculate the first voltage change rate for the Ca cycle, the Cb cycle, and the Cc cycle. The first voltage change rate of the Ca cycle is dVa, the first voltage change rate of the Cb cycle is dVb, and the first voltage change rate of the Cc cycle is dVc.

[0061] The control unit (120) may be configured to compare at least one first voltage change rate produced with a preset first reference change rate.

[0062] Specifically, the control unit (120) can compare the magnitude of the first voltage change rate and the first reference change rate. That is, the control unit (120) can directly compare the magnitude of the first voltage change rate and the first reference change rate.

[0063] For example, in the embodiment of Fig. 3, it is assumed that the first reference change rate is preset to VC1. The control unit (120) can compare the first reference change rate (VC1) with the first voltage change rate (dVa) of the Ca cycle, the first voltage change rate (dVb) of the Cb cycle, and the first voltage change rate (dVc) of the Cc cycle, respectively.

[0064] The control unit (120) may be configured to diagnose the condition of the battery based on the comparison result.

[0065] Specifically, the control unit (120) can diagnose the battery's status as a normal state or a lithium plating state based on the comparison result between the first reference change rate and the first voltage change rate. A specific example of the first reference change rate will be described below.

[0066] Here, the normal state refers to a state in which lithium plating has not occurred on the battery. The lithium plating state refers to a state in which lithium metal has been deposited on the battery.

[0067] For example, the control unit (120) may be configured to diagnose the state of the battery as a lithium plating state if at least one of the first voltage change rates is greater than or equal to the first reference change rate. That is, if even the first voltage change rate corresponding to one cycle is greater than or equal to the first reference change rate, the control unit (120) may diagnose the state of the battery as a lithium plating state. Conversely, if all of the calculated one or more first voltage change rates are less than the first reference change rate, the control unit (120) may diagnose the state of the battery as a normal state.

[0068] Specifically, when lithium plating occurs, the intercalation of lithium ions into the graphite layer does not proceed smoothly, so the voltage of the battery may increase even after the discharge of the battery is terminated. In particular, as the degree of lithium plating becomes more severe (i.e., as the amount of lithium precipitated increases), the voltage increase after the discharge is terminated may increase. Therefore, the control unit (120) can diagnose whether lithium plating has occurred in the battery by considering the first voltage change rate indicating the voltage increase after the discharge is terminated.

[0069] A battery diagnostic device (100) according to one embodiment of the present invention has the advantage of being able to non-destructively diagnose whether lithium plating has occurred in a battery based on the cycle-by-cycle voltage change rate of the battery.

[0070]

[0071] Meanwhile, the profile acquisition unit (110) and the control unit (120) provided in the battery diagnostic device (100) may optionally include a processor, an application-specific integrated circuit (ASIC), 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. In addition, when the control logic is implemented in software, the profile acquisition unit (110) and the control unit (120) may be implemented as a set of program modules. At this time, the program modules may be stored in a memory and executed by the profile acquisition unit (110) and the control unit (120). The memory may be located inside or outside the profile acquisition unit (110) and the control unit (120), and may be connected to the profile acquisition unit (110) and the control unit (120) by various well-known means.

[0072] In addition, the battery diagnostic device (100) may further include a storage unit (130). The storage unit (130) may store data or programs required for each component of the battery diagnostic device (100) to perform operations and functions, or data generated in the process of performing operations and functions. The storage unit (130) is not particularly limited in type as long as it is a known information storage means known to be capable of recording, erasing, updating, and reading data. As an example, the information storage means may include RAM, flash memory, ROM, EEPROM, registers, etc. In addition, the storage unit (130) may store program codes defining processes executable by the profile acquisition unit (110) and the control unit (120).

[0073]

[0074] Preferably, the control unit (120) may be configured to calculate the first voltage change rate for a cycle greater than or equal to a preset reference cycle among a plurality of cycles.

[0075] Specifically, even if lithium plating does not occur during the initial cycle, the battery voltage may gradually increase. For example, as the battery's cathode stabilization phase progresses during the initial cycle, the battery's OCV may gradually increase after discharge ends.

[0076] In the embodiment of FIG. 2, the battery voltage gradually increases below the Cr cycle, the battery voltage is maintained at a constant level after the Cr cycle, and the battery voltage increases rapidly after approximately the Ca cycle. Accordingly, the reference cycle may be preset as the Cr cycle. For example, the reference cycle may be preset as approximately 25 cycles.

[0077] That is, considering the electrochemical state change of the battery, the first voltage change rate in the initial cycle may be higher than the first reference change rate due to reasons unrelated to lithium plating. If the battery condition is diagnosed for the entire cycle without considering these battery characteristics, the battery condition may be incorrectly diagnosed. Therefore, the battery diagnosis device (100) can prevent misdiagnosis of the battery condition by diagnosing the battery condition in cycles greater than the reference cycle.

[0078]

[0079] Below, a specific example of the first reference change rate is described.

[0080] In one embodiment, the first reference change rate is a preset value, which may be determined theoretically or experimentally. For example, the first reference change rate may be preset to 0.002. That is, if the first voltage change rate is greater than or equal to 0.002, the battery's condition may be diagnosed as a lithium plating state.

[0081] In another embodiment, the first reference rate of change may be preset to a value less than or equal to a voltage rate of change corresponding to the first cycle of the voltage profile.

[0082] If the first reference rate of change is set too low, even a slight increase in the first voltage rate of change can lead to the battery being diagnosed as having lithium plating. Since lithium plating can lead to stricter battery usage conditions or even bans, incorrectly diagnosing a battery as having lithium plating can severely reduce its utility.

[0083] Conversely, if the first reference rate of change is set too high, the battery may be misdiagnosed as normal, even though lithium plating has actually occurred. This can lead to accidents such as venting and explosion due to swelling.

[0084] Preferably, the first reference change rate may be set to a value lower than or equal to the first voltage change rate of the first cycle of the battery. More preferably, the first reference change rate may be set to the first voltage change rate of the first cycle of the battery.

[0085] In the embodiment of FIG. 3, the first voltage change rate in the first cycle is the largest, VC1, below the reference cycle (Cr). For example, the first reference change rate may be set to the first voltage change rate (VC1) of the first cycle. Alternatively, the first reference change rate may be set to a value lower than or equal to the first voltage change rate (VC1) of the first cycle.

[0086] The battery diagnosis device (100) according to one embodiment of the present invention can set the first reference change rate, which serves as a criterion for diagnosing the state of the battery, based on the first voltage change rate in the initial cycle of the battery. That is, since the battery diagnosis device (100) does not set the first reference change rate to a uniform value but sets it by considering the state of each battery, it has the advantage of being able to diagnose the state of the battery more adaptively.

[0087]

[0088] The control unit (120) may be configured to select a target cycle corresponding to a first voltage change rate that is greater than or equal to a first reference change rate.

[0089] For example, in the embodiment of FIG. 3, assuming that the first reference change rate is set to VC1, the control unit (120) can select the Ca cycle and the Cb cycle as target cycles.

[0090] The control unit (120) may be configured to determine a cycle section for a selected target cycle based on a preset section size.

[0091] Here, the interval size can be preset to a size that allows for monitoring the battery's voltage change behavior. For example, the interval size can be preset to a size greater than one cycle. The following description assumes that the interval size is preset to R cycles.

[0092] Specifically, a cycle interval may include an interval corresponding to a preset interval size from a target cycle. For example, assuming that the target cycle is n cycles and the preset interval size is R, a cycle interval for n cycles means n to n+R cycles.

[0093] FIG. 4 is a diagram illustrating another embodiment of a first voltage profile (VP1) according to one embodiment of the present invention. For example, the first cycle section (R1) for the Ca cycle is the Ca to Cd cycle, where the equation "Cd = Ca + R" is satisfied. In addition, the second cycle section (R2) for the Cb cycle is the Cb to Ce cycle, where the equation "Ce = Cb + R" is satisfied.

[0094] However, target cycles whose cycle intervals cannot be determined among the target cycles may be excluded from the battery condition diagnosis process. For example, a cycle interval refers to an interval with a preset interval size from the target cycle. In other words, a cycle whose difference from the last cycle is greater than the preset interval size may be determined as the target cycle.

[0095] For example, in the embodiments of FIGS. 2 and 3, there are multiple target cycles between the Cb cycle and the Cc cycle in which the first voltage change rate is greater than or equal to the first reference change rate (VC1). However, the cycle section set based on these target cycles includes cycles exceeding the Cc cycle.

[0096] For example, it is assumed that the Cs cycle (not shown) located between the Cb cycle and the Cc cycle corresponds to a target cycle in which the first voltage change rate is greater than or equal to the first reference change rate (VC1), and the formula "R > Cc - Cs" is satisfied. Here, R is a preset interval size.

[0097] Since the cycle interval set based on the Cs cycle is the Cs to Cs+R cycle, cycles exceeding the Cc cycle are included in the set cycle interval. Since the voltage profile does not contain voltage data for cycles exceeding the Cc cycle, the Cs cycle corresponds to the target cycle but can be excluded during the battery condition diagnosis process.

[0098] The control unit (120) may be configured to diagnose the state of the battery as a lithium plating state if at least one of the second voltage change rates for the determined cycle section is greater than or equal to a preset second reference change rate.

[0099] Specifically, the control unit (120) can calculate a second voltage change rate for the determined cycle section. Here, the second voltage change rate is the average voltage change rate for the corresponding cycle section. That is, the average voltage change rate during the cycle section can be calculated as the second voltage change rate.

[0100] In the embodiment of Fig. 4, the voltage corresponding to the Ca cycle is Va, and the voltage corresponding to the Cd cycle is Vd. The control unit (120) can calculate the second voltage change rate of the first cycle section (R1) according to the formula “(Vd-Va)÷(Cd-Ca)”.

[0101] Additionally, in the embodiment of FIG. 4, the voltage corresponding to the Cb cycle is Vb, and the voltage corresponding to the Ce cycle is Ve. The control unit (120) can calculate the second voltage change rate of the second cycle section (R2) according to the formula “(Ve-Vb)÷(Ce-Cb)”.

[0102] In addition, the control unit (120) can compare each of the calculated second voltage change rates with a preset second reference change rate. Here, the first reference change rate can be preset to a value greater than or equal to the second reference change rate. That is, since the second reference change rate is a value compared to the average change rate of the voltage for the cycle section, it can be set to a value less than or equal to the first reference change rate compared to the instantaneous change rate of the voltage for the cycle.

[0103] If at least one of the calculated second voltage change rates is greater than or equal to the second reference change rate, the control unit (120) can diagnose the state of the battery as a lithium plating state. Specifically, the target cycle that serves as the criterion for calculating the second voltage change rate is a cycle in which the corresponding first voltage change rate is greater than or equal to the first reference change rate. That is, if there is a cycle in which the corresponding first voltage change rate is greater than or equal to the first reference change rate and the corresponding second voltage change rate is greater than or equal to the second reference change rate, the control unit (120) can diagnose the state of the battery as a lithium plating state.

[0104] For example, in the embodiment of FIG. 3, the first voltage change rate of the Ca cycle is dVa, which is equal to the first reference change rate (VC1), and the first voltage change rate of the Cb cycle is dVb, which is greater than the first reference change rate (VC1). In addition, in the embodiments of FIGS. 3 and 4, the second voltage change rates of the first cycle section (R1) and the second cycle section (R2) are greater than the first reference change rate (VC1), and therefore are greater than or equal to the second reference change rate. Therefore, the control unit (120) can diagnose the state of the battery as a lithium plating state.

[0105] If, contrary to the embodiments of FIGS. 3 and 4, the first voltage change rate after the Ca cycle and the Cb cycle decreases rapidly, and the second voltage change rate of the first cycle section (R1) and the second cycle section (R2) is less than the second reference change rate, then in this case, although the first voltage change rate corresponding to the Ca cycle and the Cb cycle is greater than or equal to the first reference change rate (VC1), the control unit (120) can diagnose the state of the battery as being normal.

[0106] For example, since the first voltage change rate represents the instantaneous voltage change rate for a cycle, the first voltage change rate may be calculated to be higher than the actual value due to various reasons such as voltage measurement noise or process noise. In other words, if the battery condition is diagnosed by considering only the voltage change rate for one cycle, the battery condition may be misdiagnosed. Therefore, the battery diagnosis device (100) has the advantage of being able to diagnose the battery condition more accurately by considering both the first voltage change rate and the second voltage change rate.

[0107]

[0108] Figure 5 is a schematic diagram illustrating the first to fifth voltage profiles (VP1, VP2, VP3, VP4, VP5).

[0109] Specifically, the first to fifth voltage profiles (VP1, VP2, VP3, VP4, VP5) are voltage profiles for the first to fifth batteries, respectively. That is, the first to fifth voltage profiles (VP1, VP2, VP3, VP4, VP5) are profiles representing the OCV after the end of cycle-by-cycle discharge for the first to fifth batteries, respectively.

[0110] Also, the first and fourth batteries are in a lithium plating state, while the second, third, and fifth batteries are in a normal state. Lithium plating occurred in the Ca cycle for the first battery, and lithium plating occurred in the Cf cycle for the fourth battery.

[0111] The voltages of the first and second batteries are the same in the C2 cycle, but the state of the first battery is in a lithium-plated state, while the state of the second battery is in a normal state. Furthermore, the voltages of the first and third batteries are the same in the C1 cycle, but the state of the first battery is in a lithium-plated state, while the state of the third battery is in a normal state.

[0112] The voltages of the fourth battery and the second battery are the same in the C4 cycle, but the fourth battery is in a lithium-plated state, while the second battery is in a normal state. Furthermore, the voltages of the fourth battery and the third battery are the same in the C3 cycle, but the fourth battery is in a lithium-plated state, while the third battery is in a normal state.

[0113] That is, even if the battery's voltage is the same for each cycle, the battery's condition can vary significantly, making it impossible to accurately diagnose the battery's condition based on the battery's voltage for each cycle. Therefore, the battery diagnostic device (100) according to one embodiment of the present invention has the advantage of being able to more accurately diagnose the battery's condition by taking into account the battery's voltage change rate.

[0114]

[0115] Hereinafter, an embodiment in which the control unit (120) determines the start cycle of lithium plating will be described. That is, the control unit (120) can not only diagnose whether the state of the battery is a lithium plating state, but also determine the start cycle in which lithium plating of the battery begins.

[0116] In one embodiment, the control unit (120) can determine the start cycle of lithium plating based on the result of comparing the first voltage change rate and the first reference change rate.

[0117] The control unit (120) may be configured to calculate a first voltage change rate for each of a plurality of cycles. Preferably, the control unit (120) may calculate the first voltage change rate for a plurality of cycles included in the voltage profile to accurately determine the start cycle at which lithium plating begins. More preferably, the control unit (120) may calculate the first voltage change rate for a cycle greater than or equal to a preset reference cycle among the plurality of cycles included in the voltage profile.

[0118] For example, in the embodiment of FIG. 2, the control unit (120) can calculate the first voltage change rate for each of the Cr to Cc cycles.

[0119] The control unit (120) may be configured to select a target cycle among a plurality of cycles in which the corresponding first voltage change rate is greater than or equal to the first reference change rate. In addition, the control unit (120) may be configured to determine the minimum cycle among the selected target cycles as the start cycle of lithium plating.

[0120] Specifically, when lithium plating occurs, the battery voltage may increase even after the battery discharge is completed. Accordingly, the control unit (120) may determine the minimum cycle among the cycles in which the first voltage change rate of the battery is greater than or equal to the first reference change rate as the start cycle of lithium plating.

[0121] The battery diagnostic device (100) has the advantage of not only being able to diagnose the state of a battery as being normal or in a lithium plating state, but also being able to determine the cycle in which lithium plating begins in the battery. That is, according to the battery diagnostic device (100), since the start cycle of lithium plating can be determined, the lithium plating state of the battery can be tracked and diagnosed. Specifically, whether additional lithium plating of the battery has occurred and the amount of lithium deposited can be tracked and diagnosed.

[0122] For example, in the embodiment of FIG. 3, after the Ca cycle, three peaks (points with upward convex shapes) exist. In this case, lithium plating can be diagnosed as having occurred a total of three times. Furthermore, the integral value for the cycle region where the first voltage change rate is greater than the first reference change rate can be diagnosed as the amount of lithium deposited.

[0123]

[0124] In another embodiment, the control unit (120) may compare the first voltage change rate with the first reference change rate and determine the start cycle of lithium plating based on the result of comparing the second voltage change rate with the second reference change rate.

[0125] The control unit (120) may be configured to determine a cycle section for a selected target cycle based on a preset interval size. Furthermore, the control unit (120) may be configured to calculate a second voltage change rate for the determined cycle section. Since the preset interval size, target cycle, cycle section, and second voltage change rate described herein are identical to those described above, a detailed description thereof will be omitted.

[0126] The control unit (120) may be configured to determine the minimum cycle among the selected target cycles in which the corresponding second voltage change rate is greater than or equal to a preset second reference change rate as the start cycle of lithium plating.

[0127] As previously explained, the first voltage change rate may differ from the actual value due to the influence of various noises. Therefore, to prevent misdiagnosis due to noise, the second voltage change rate for a certain cycle section may be considered. Accordingly, the control unit (120) may determine the cycle section for each target cycle and calculate the second voltage change rate for each determined cycle section. In addition, the control unit (120) may determine the minimum cycle in which the second voltage change rate is greater than or equal to the second reference change rate as the start cycle of lithium plating.

[0128] The battery diagnostic device (100) has the advantage of being able to more accurately determine the start cycle of lithium plating of the battery by considering both the corresponding first voltage change rate and the corresponding second voltage change rate.

[0129]

[0130] Meanwhile, the control unit (120) may be configured to set the usage conditions of the battery, including at least one of the maximum allowable C-rate, the maximum allowable temperature, and the maximum allowable SOC, based on the state of the battery.

[0131] Specifically, the control unit (120) may set the usage conditions of the battery to prevent additional lithium plating from occurring on the battery. For example, the control unit (120) may set at least one of the maximum allowable C-rate, maximum allowable temperature, and maximum allowable SOC to be lower than a previously set value.

[0132]

[0133] The battery diagnosis device (100) according to the present invention can be applied to a BMS (Battery Management System). That is, the BMS according to the present invention can include the battery diagnosis device (100) described above. In this configuration, at least some of the components of the battery diagnosis device (100) can be implemented by supplementing or adding to the functions of the components included in a conventional BMS. For example, the profile acquisition unit (110) and the control unit (120) of the battery diagnosis device (100) can be implemented as components of the BMS.

[0134]

[0135] In addition, the battery diagnostic device (100) according to the present invention may be installed in a battery pack. That is, the battery pack 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 may further include electrical components (relays, fuses, etc.) and a case, etc.

[0136] FIG. 6 is a drawing illustrating an exemplary configuration of a battery pack including a battery diagnostic device (100) according to one embodiment of the present invention.

[0137] 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).

[0138] The measuring unit (12) can be connected to a first sensing line (SL1), a second sensing line (SL2), and a third sensing line (SL3). Specifically, the measuring unit (12) can be connected to a positive terminal of the battery (11) through the first sensing line (SL1), and can be connected to a 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).

[0139] And, the measuring unit (12) can be connected to the current measuring unit (A) through the third sensing line (SL3). For example, the current measuring unit (A) can be an ammeter or a shunt resistor capable of measuring the discharge current and discharge current of the battery (11). The measuring unit (12) can measure the discharge current of the battery (11) through the third sensing line (SL3) to calculate the discharge amount. In addition, the measuring unit (12) can measure the discharge current of the battery (11) through the third sensing line (SL3) to calculate the discharge amount.

[0140] For example, the profile acquisition unit (110) can receive battery information about the voltage of the battery from the measurement unit (12). Then, the profile acquisition unit (110) can generate a voltage profile based on the battery information.

[0141] As another example, the profile acquisition unit (110) can receive a voltage profile from the measurement unit (12).

[0142] An external device may be connected to the positive terminal (P+) and negative terminal (P-) of the battery pack (10). For example, the external device may be a discharge device or a load. In addition, the positive terminal of the battery (11), the positive terminal (P+) of the battery pack (10), the external device, the negative terminal (P-) of the battery pack (10), and the negative terminal of the battery (11) may be electrically connected.

[0143]

[0144] FIG. 7 is a schematic diagram illustrating a server (700) according to another embodiment of the present invention.

[0145] A server (700) according to another embodiment of the present invention may include a battery diagnostic device (100).

[0146] The server (700) may be configured to receive a voltage profile for a battery from an external source. Specifically, the server (700) may be connected to any device capable of generating and transmitting a voltage profile for a battery, so as to enable communication without limitation.

[0147] For example, the server (700) may be connected to one or more BMSs to enable wired and / or wireless communication. For example, the server (700) may be connected to enable communication with a BMS, a vehicle BMS installed in a vehicle, an ESS BMS installed in an ESS, etc.

[0148] As another example, the server (700) may be connected to a device capable of controlling the charging and discharging of a battery, such as a BMS or a charging / discharging station. Furthermore, the server (700) may be connected to one or more user terminals. Furthermore, the server (700) may be connected to a battery testing device that tests the condition of the battery.

[0149] The server (700) can diagnose the status of the battery based on the voltage profile and set usage conditions for the battery based on the diagnosed status of the battery.

[0150] For example, if the battery is diagnosed as being in a lithium plating state, the server (700) may reduce the setting value for at least one of the maximum allowable temperature, the maximum allowable C-rate, and the maximum allowable SOC for the battery. Furthermore, the server (700) may feed back the changed setting value to a device corresponding to the battery. The device corresponding to the battery may receive the changed setting value from the server (700) and change the usage conditions of the battery to correspond to the received setting value. Accordingly, the battery may be operated according to the changed usage conditions, thereby preventing additional occurrence of lithium plating.

[0151]

[0152] FIG. 8 is a schematic drawing of a vehicle (800) according to another embodiment of the present invention.

[0153] Referring to FIG. 8, a battery pack (810) according to an embodiment of the present invention may be included in a vehicle (800), such as an electric vehicle (EV) or a hybrid vehicle (HV). Furthermore, the battery pack (810) may drive the vehicle (800) by supplying power to a motor through an inverter provided in the vehicle (800). Here, the battery pack (810) may include a battery diagnostic device (100). That is, the vehicle (800) may include a battery diagnostic device (100). In this case, the battery diagnostic device (100) may be an onboard device included in the vehicle (900).

[0154]

[0155] FIG. 9 is a diagram schematically illustrating a battery management method according to another embodiment of the present invention.

[0156] Referring to FIG. 9, the battery diagnosis method may include a profile acquisition step (S100), a voltage change rate calculation step (S200), a comparison step (S300), and a battery status diagnosis step (S400).

[0157] Preferably, each step of the battery diagnosis method can be performed by the battery diagnosis device (100). In the following, for convenience of explanation, any content that overlaps with the previously described content will be omitted or briefly described.

[0158] The profile acquisition step (S100) is a step of acquiring a voltage profile representing the voltage of the battery for multiple cycles, and can be performed by the profile acquisition unit (110).

[0159] For example, the profile acquisition unit (110) can directly receive the voltage profile of the battery from the outside. That is, the profile acquisition unit (110) can acquire the voltage profile by receiving the voltage profile through a wired and / or wireless connection to the outside.

[0160] As another example, the profile acquisition unit (110) can receive battery information regarding the battery voltage for each cycle. Furthermore, the profile acquisition unit (110) can generate a voltage profile based on the received battery information. In other words, the profile acquisition unit (110) can acquire a voltage profile by directly generating the voltage profile based on the battery information.

[0161] The voltage change rate calculation step (S200) is a step of calculating a first voltage change rate for at least one cycle based on a voltage profile, and can be performed by the control unit (120).

[0162] Specifically, the control unit (120) can calculate the first voltage change rate for at least one cycle by calculating the voltage change rate for the cycle. That is, the first voltage change rate can be a value obtained by differentiating the voltage for the cycle.

[0163] The comparison step (S300) is a step of comparing at least one first voltage change rate produced with a preset first reference change rate, and can be performed by the control unit (120).

[0164] Specifically, the control unit (120) can compare the magnitude of the first voltage change rate and the first reference change rate. That is, the control unit (120) can directly compare the magnitude of the first voltage change rate and the first reference change rate.

[0165] The battery status diagnosis step (S400) is a step for diagnosing the status of the battery based on the comparison result of the comparison step (S300), and can be performed by the control unit (120).

[0166] For example, the control unit (120) may be configured to diagnose the state of the battery as a lithium plating state if at least one of the first voltage change rates is greater than or equal to the first reference change rate.

[0167] As another example, the control unit (120) can diagnose the state of the battery as normal if all of the one or more calculated first voltage change rates are less than the first reference change rate.

[0168]

[0169] The embodiments of the present invention described above are not implemented only through devices and methods, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation can be easily implemented by an expert in the technical field to which the present invention belongs based on the description of the embodiments described above.

[0170] Another embodiment of the present invention can provide a computer-readable recording medium having recorded thereon a program for performing the various embodiments described above on a computer.

[0171] The program may be implemented as hardware components, software components, and / or a combination of hardware components and software components. The program may be executed by any system capable of executing computer-readable instructions.

[0172] Software may include computer programs, codes, instructions, or any combination thereof, which may configure a processing device to perform a desired operation or may independently or collectively command a processing device.

[0173] Software may be implemented as a computer program comprising instructions stored on a computer-readable storage medium. Examples of computer-readable storage media include magnetic storage media (e.g., read-only memory (ROM), random-access memory (RAM), floppy disks, hard disks, etc.) and optical reading media (e.g., CD-ROMs, Digital Versatile Discs (DVDs)). The computer-readable storage media may be distributed across network-connected computer systems, so that computer-readable code may be stored and executed in a distributed manner. The storage media may be readable by a computer, stored in a memory, and executed by a processor.

[0174] Computer-readable storage media may be provided in the form of non-transitory storage media. Here, the term "non-transitory storage media" simply means a tangible device that does not contain signals (e.g., electromagnetic waves). This term does not distinguish between cases where data is permanently stored on the storage media and cases where data is temporarily stored. For example, a "non-transitory storage medium" may include a buffer in which data is temporarily stored.

[0175] Additionally, the program may be provided as part of a computer program product. The computer program product may be traded as a commodity between sellers and buyers.

[0176] A computer program product may include a software program or a computer-readable storage medium storing the software program. For example, a computer program product may include a product in the form of a software program (e.g., a downloadable application) distributed electronically by an electronic device manufacturer or through an electronic marketplace. For electronic distribution, at least a portion of the software program may be stored on a storage medium or temporarily generated. In this case, the storage medium may be a storage medium of the electronic device manufacturer's server, an electronic marketplace server, or an intermediary server that temporarily stores the software program.

[0177] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0178] In addition, the present invention described above is not limited to the above-described embodiments and the attached drawings, and all or part of each embodiment may be selectively combined and configured so that various modifications can be made, as those skilled in the art can make various substitutions, modifications, and changes within the scope of the technical idea of ​​the present invention.

[0179] (Explanation of symbols)

[0180] 10: Battery pack

[0181] 11: Battery

[0182] 12: Measurement section

[0183] 100: Battery Diagnostic Device

[0184] 110: Profile acquisition section

[0185] 120: Control unit

[0186] 130: Storage

[0187] 700: Server

[0188] 800: Car

[0189] 810: Battery Pack

Claims

1. A profile acquisition unit configured to acquire a voltage profile representing the voltage of a battery for multiple cycles; and A battery diagnostic device comprising a control unit configured to calculate a first voltage change rate for at least one cycle based on the voltage profile, compare the calculated at least one first voltage change rate with a preset first reference change rate, and diagnose the state of the battery based on the comparison result.

2. In paragraph 1, The above control unit, A battery diagnostic device configured to diagnose the state of the battery as a lithium plating state if at least one of the first voltage change rates is greater than or equal to the first reference change rate.

3. In paragraph 2, The above control unit, Select a target cycle corresponding to the first voltage change rate that is greater than or equal to the first reference change rate, Determine the cycle interval for the selected target cycle based on the preset interval size, A battery diagnostic device configured to diagnose the state of the battery as a lithium plating state if at least one of the second voltage change rates for the determined cycle section is greater than or equal to a preset second reference change rate.

4. In paragraph 3, The above first reference rate of change is, A battery diagnostic device preset to a value greater than or equal to the second reference change rate.

5. In paragraph 1, The above first reference rate of change is, A battery diagnostic device preset to a value lower than or equal to the voltage change rate corresponding to the first cycle of the above voltage profile.

6. In paragraph 1, The above control unit, Calculate the first voltage change rate for each of the plurality of cycles, Among the above multiple cycles, a target cycle is selected in which the corresponding first voltage change rate is greater than or equal to the first reference change rate, A battery diagnostic device configured to determine the minimum cycle among the above-mentioned selected target cycles as the start cycle of lithium plating.

7. In paragraph 6, The above control unit, Determine the cycle interval for the selected target cycle based on the preset interval size, Calculate the second voltage change rate for the determined cycle section, A battery diagnostic device configured to determine the minimum cycle among the selected target cycles in which the corresponding second voltage change rate is greater than or equal to a preset second reference change rate as the start cycle of the lithium plating.

8. In paragraph 1, The above control unit, A battery diagnostic device configured to calculate the first voltage change rate for a cycle greater than or equal to a preset reference cycle among the plurality of cycles.

9. In paragraph 1, The above control unit, A battery diagnostic device configured to set usage conditions of the battery, including at least one of a maximum allowable C-rate, a maximum allowable temperature, and a maximum allowable SOC, based on the state of the battery.

10. In paragraph 1, The voltage of the above battery is, A battery diagnostic device wherein the OCV of the battery is measured after the discharge of the battery is completed in each of the plurality of cycles.

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

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

13. A profile acquisition step for acquiring a voltage profile representing the voltage of the battery for multiple cycles; A voltage change rate calculation step for calculating a first voltage change rate for at least one cycle based on the voltage profile; A comparison step of comparing at least one first voltage change rate produced with a preset first reference change rate; and A battery diagnosis method including a battery status diagnosis step for diagnosing the status of the battery based on the comparison result of the above comparison step.

14. A profile acquisition step for acquiring a voltage profile representing the voltage of the battery for multiple cycles; A voltage change rate calculation step for calculating a first voltage change rate for at least one cycle based on the voltage profile; A comparison step of comparing at least one first voltage change rate produced with a preset first reference change rate; and A computer-readable recording medium storing a computer program for executing a battery diagnosis method including a battery status diagnosis step of diagnosing the status of the battery based on the comparison result of the above comparison step.

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